U.S. patent application number 10/337477 was filed with the patent office on 2003-06-12 for magnetoresistive-effect device and method for manufacturing the same.
This patent application is currently assigned to Alps Electric Co., Ltd.. Invention is credited to Aoki, Daigo, Hasegawa, Naoya, Honda, Kenji, Kakihara, Yoshihiko.
Application Number | 20030107850 10/337477 |
Document ID | / |
Family ID | 27279525 |
Filed Date | 2003-06-12 |
United States Patent
Application |
20030107850 |
Kind Code |
A1 |
Aoki, Daigo ; et
al. |
June 12, 2003 |
Magnetoresistive-effect device and method for manufacturing the
same
Abstract
A magnetoresistive-effect device includes a multilayer film,
hard bias layers arranged on both sides of the multilayer film, and
electrode layers respectively deposited on the hard bias layers.
The electrode layers are formed, extending over the multilayer
film. Under the influence of the hard bias layers arranged on both
sides of the multilayer, the multilayer film, forming the
magnetoresistive-effect device, has, on the end portions thereof,
insensitive regions which exhibit no substantial magnetoresistive
effect. The insensitive region merely increases a direct current
resistance. By extending the electrode layers over the insensitive
regions of the multilayer film, a sense current is effectively
flown from the electrode layer into the multilayer film. With a
junction area between the electrode layer and the multilayer film
increased, the direct current resistance is reduced, while the
reproduction characteristics of the device are thus improved.
Inventors: |
Aoki, Daigo; (Niigata-ken,
JP) ; Hasegawa, Naoya; (Niigata-ken, JP) ;
Honda, Kenji; (Niigata-ken, JP) ; Kakihara,
Yoshihiko; (Niigata-ken, JP) |
Correspondence
Address: |
Gustavo Siller, Jr.
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
Alps Electric Co., Ltd.
|
Family ID: |
27279525 |
Appl. No.: |
10/337477 |
Filed: |
January 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10337477 |
Jan 6, 2003 |
|
|
|
09487691 |
Jan 19, 2000 |
|
|
|
Current U.S.
Class: |
360/324.1 ;
257/E43.004; 257/E43.006; 360/322 |
Current CPC
Class: |
Y10T 29/49044 20150115;
G11B 2005/3996 20130101; B82Y 25/00 20130101; H01L 43/08 20130101;
H01L 43/12 20130101; B82Y 10/00 20130101; G11B 5/3903 20130101 |
Class at
Publication: |
360/324.1 ;
360/322 |
International
Class: |
G11B 005/39 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 1999 |
JP |
11-011670 |
Jan 25, 1999 |
JP |
11-015358 |
Dec 2, 1999 |
JP |
11-343134 |
Claims
What is claimed is:
1. A magnetoresistive-effect device comprising a multilayer film
comprising an antiferromagnetic layer, a pinned magnetic layer,
which is deposited on and in contact with said antiferromagnetic
layer, and the magnetization direction of which is pinned through
an exchange anisotropic magnetic field with said antiferromagnetic
layer, and a free magnetic layer, separated from said pinned
magnetic layer by a nonmagnetic electrically conductive layer, a
pair of hard bias layers, deposited on both sides of said
multilayer film, for orienting the magnetization direction of said
free magnetic layer perpendicular to the magnetization direction of
said pinned magnetic layer, and a pair of electrode layers
respectively deposited on said hard bias layers, wherein said
electrode layers extend over said multilayer film.
2. A magnetoresistive-effect device according to claim 1, wherein
said multilayer film is fabricated by successively laminating said
antiferromagnetic layer, said pinned magnetic layer, said
nonmagnetic electrically conductive layer, and said free magnetic
layer in that order from below, said antiferromagnetic layer
laterally extends from the layers laminated thereon, and a pair of
hard bias layer, a pair of intermediate layers, and a pair of
electrode layers are respectively laminated on a pair of metallic
layers respectively deposited on said antiferromagnetic layers in
said laterally extending regions thereof.
3. A magnetoresistive-effect device according to claim 1, wherein
said electrode layer feeds a sense current to each of said pinned
magnetic layer, said nonmagnetic electrically conductive layer, and
said free magnetic layer.
4. A magnetoresistive-effect device according to claim 1, wherein
said free magnetic layer comprises a plurality of soft magnetic
thin films having different magnetic moments and nonmagnetic
material layers, which are alternately laminated with one soft
magnetic thin film separated from another by one nonmagnetic
material layer, and said free magnetic layer is in a ferrimagnetic
state in which the magnetization directions of two adjacent soft
magnetic thin films, separated by the nonmagnetic material layer,
are aligned antiparallel to each other.
5. A magnetoresistive-effect device according to claim 4, wherein
the magnetic coupling junction between said multilayer film and
said bias layer is fabricated of an interface with the end face of
only one of the plurality of the soft magnetic thin films forming
said free magnetic layer.
6. A magnetoresistive-effect device according to claim 1, wherein
said pinned magnetic layer comprises a plurality of soft magnetic
thin films having different magnetic moments and nonmagnetic
material layers, which are alternately laminated with one soft
magnetic thin film separated from another by one nonmagnetic
material layer, and said pinned magnetic layer is in a
ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
7. A magnetoresistive-effect device according to claim 4, wherein
said nonmagnetic material layer is made of a material selected from
the group consisting of Ru, Rh, Ir, Cr, Re, Cu, and alloys
thereof.
8. A magnetoresistive-effect device according to claim 1, wherein
said antiferromagnetic layer is made of a PtMn alloy.
9. A magnetoresistive-effect device according to claim 1, wherein
said antiferromagnetic layer is made of an X--Mn alloy where X is a
material selected from the group consisting of Pd, Ir, Rh, Ru, and
alloys thereof.
10. A magnetoresistive-effect device according to claim 1, wherein
said antiferromagnetic material is made of a Pt--Mn--X' alloy where
X' is a material selected from the group consisting of Pd, Ir, Rh,
Ru, Au, Ag, and alloys thereof.
11. A magnetoresistive-effect device according to claim 1, wherein
the position of at least one of the top edge and the bottom edge of
the magnetic coupling junction between said multilayer film and
said bias layer in the direction of the movement of a medium is at
the same level as the position of at least one of the top surface
and the bottom surface of said free magnetic layer in the direction
of the movement of the medium.
12. A magnetoresistive-effect device according to claim 1, wherein
a protective layer is deposited, as a top layer, on top of said
multilayer film.
13. A magnetoresistive-effect device according to claim 12, wherein
said protective layer is deposited where there is no junction
between said multilayer film and said electrode layer.
14. A magnetoresistive-effect device according to claim 1, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is within a range from 0 .mu.m to 0.08
.mu.m.
15. A magnetoresistive-effect device according to claim 14, wherein
the width dimension of the portion of each electrode layer
extending over said multilayer film is equal to or larger than 0.05
.mu.m.
16. A magnetoresistive-effect device according to claim 1, wherein
an insulator layer is deposited between said electrode layers,
which are deposited above and on both sides of said multilayer
film, and the end face of said insulator layer is in direct contact
with each of said electrode layers or is separated from each of
said electrode layers by a layer.
17. A magnetoresistive-effect device according to claim 1, wherein
said multilayer film comprises a central sensitive region which
provides an excellent reproduction gain, exhibiting a substantial
magnetoresistive effect and insensitive regions which are formed on
both sides of said sensitive region, and provide a poor
reproduction gain, exhibiting no substantial magnetoresistive
effect, and wherein said electrode layers deposited on both sides
of said multilayer film extend over the insensitive regions of said
multilayer film.
18. A magnetoresistive-effect device according to claim 17, wherein
said sensitive region of said multilayer film is defined as a
region which results in an output equal to or greater than 50% of a
maximum reproduction output while said insensitive regions of said
multilayer film are defined as regions, formed on both sides of
said sensitive region, which result in an output smaller than 50%
of the maximum reproduction output, when the
magnetoresistive-effect device having the electrode layers
deposited on both sides only of said multilayer film scans a micro
track, having a signal recorded thereon, in the direction of a
track width.
19. A magnetoresistive-effect device according to claim 17, wherein
the width dimension of said sensitive region of said multilayer
film is equal to an optical track width.
20. A magnetoresistive-effect device according to claim 17, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
21. A magnetoresistive-effect device according to claim 17, wherein
the angle made between the surface of said multilayer film and the
end face of said electrode layer extending over said insensitive
region of said multilayer film is within a range of 25 degrees to
45 degrees.
22. A magnetoresistive-effect device according to claim 17, wherein
a protective layer is deposited, as a top layer, on top of said
multilayer film.
23. A magnetoresistive-effect device according to claim 22, wherein
an insulator layer is deposited between said electrode layers,
which are deposited above and on both sides of said multilayer
film, and the end face of said insulator layer is in direct contact
with said electrode layer or is separated from said electrode layer
by a layer.
24. A magnetoresistive-effect device according to claim 22, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
25. A magnetoresistive-effect device according to claim 22, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 25 degrees to 45 degrees.
26. A magnetoresistive-effect device according to claim 23, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 60 degrees or
greater.
27. A magnetoresistive-effect device according to claim 23, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 90 degrees or
greater.
28. A magnetoresistive-effect device according to claim 27, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is equal to the width dimension of said
insensitive region of said multilayer film.
29. A magnetoresistive-effect device according to claim 1, wherein
an intermediate layer, made of at least one of a high-resistivity
material having a resistance higher than that of said electrode
layer and an insulating material, is interposed between said hard
bias layer and said electrode layer.
30. A magnetoresistive-effect device according to claim 29, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of TaSiO.sub.2, TaSi, CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and
TaN.
31. A magnetoresistive-effect device according to claim 29, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of Al.sub.2O.sub.3, SiO.sub.2, Ti.sub.2O.sub.3, TiO, WO, AlN,
Si.sub.3N.sub.4, B.sub.4C, SiC, and SiAlON.
32. A magnetoresistive-effect device comprising a multilayer film
comprising a free magnetic layer, nonmagnetic electrically
conductive layers respectively lying over and under said free
magnetic layer, pinned magnetic layers respectively lying over said
one nonmagnetic electrically conductive layer and under said other
nonmagnetic electrically conductive layer, each having a pinned
magnetization direction, and antiferromagnetic layers respectively
lying over said one pinned magnetic layer and under said other
pinned magnetic layer, and a pair of hard bias layers, deposited on
both sides of said multilayer film, for orienting the magnetization
direction of said free magnetic layer perpendicular to the
magnetization direction of said pinned magnetic layer, and a pair
of electrode layers respectively deposited on said hard bias
layers, wherein said electrode layers extend over said multilayer
film.
33. A magnetoresistive-effect device according to claim 32, wherein
said multilayer film is fabricated by successively laminating said
antiferromagnetic layer, said pinned magnetic layer, said
nonmagnetic electrically conductive layer, and said free magnetic
layer in that order from below, said antiferromagnetic layer
laterally extends from the layers laminated thereon, and a pair of
hard bias layer, a pair of intermediate layers, and a pair of
electrode layers are respectively laminated on a pair of metallic
layers respectively deposited on said antiferromagnetic layers in
said laterally extending regions thereof.
34. A magnetoresistive-effect device according to claim 32, wherein
said electrode layer feeds a sense current to each of said pinned
magnetic layer, said nonmagnetic electrically conductive layer, and
said free magnetic layer.
35. A magnetoresistive-effect device according to claim 32, wherein
said free magnetic layer comprises a plurality of soft magnetic
thin films having different magnetic moments and nonmagnetic
material layers, which are alternately laminated with one soft
magnetic thin film separated from another by one nonmagnetic
material layer, and said free magnetic layer is in a ferrimagnetic
state in which the magnetization directions of two adjacent soft
magnetic thin films, separated by the nonmagnetic material layer,
are aligned antiparallel to each other.
36. A magnetoresistive-effect device according to claim 35, wherein
the magnetic coupling junction between said multilayer film and
said bias layer is fabricated of an interface with the end face of
only one of the plurality of the soft magnetic thin films forming
said free magnetic layer.
37. A magnetoresistive-effect device according to claim 32, wherein
said pinned magnetic layer comprises a plurality of soft magnetic
thin films having different magnetic moments and nonmagnetic
material layers, which are alternately laminated with one soft
magnetic thin film separated from another by one nonmagnetic
material layer, and said pinned magnetic layer is in a
ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
38. A magnetoresistive-effect device according to claim 32, wherein
said nonmagnetic material layer is made of a material selected from
the group consisting of Ru, Rh, Ir, Cr, Re, Cu, and alloys
thereof.
39. A magnetoresistive-effect device according to claim 32, wherein
said antiferromagnetic layer is made of a PtMn alloy.
40. A magnetoresistive-effect device according to claim 32, wherein
said antiferromagnetic layer is made of an X--Mn alloy where X is a
material selected from the group consisting of Pd, Ir, Rh, Ru, and
alloys thereof.
41. A magnetoresistive-effect device according to claim 32, wherein
said antiferromagnetic material is made of a Pt--Mn--X' alloy where
X' is a material selected from the group consisting of Pd, Ir, Rh,
Ru, Au, Ag, and alloys thereof.
42. A magnetoresistive-effect device according to claim 32, wherein
the position of at least one of the top edge and the bottom edge of
the magnetic coupling junction between said multilayer film and
said bias layer in the direction of the movement of a medium is at
the same level as the position of at least one of the top surface
and the bottom surface of said free magnetic layer in the direction
of the movement of the medium.
43. A magnetoresistive-effect device according to claim 32, wherein
a protective layer is deposited, as a top layer, on top of said
multilayer film.
44. A magnetoresistive-effect device according to claim 43, wherein
said protective layer is deposited where there is no junction
between said multilayer film and said electrode layer.
45. A magnetoresistive-effect device according to claim 32, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is within a range from 0 .mu.m to 0.08
.mu.m.
46. A magnetoresistive-effect device according to claim 45, wherein
the width dimension of the portion of each electrode layer
extending over said multilayer film is equal to or larger than 0.05
.mu.m.
47. A magnetoresistive-effect device according to claim 32, wherein
an insulator layer is deposited between said electrode layers,
which are formed above and on both sides of said multilayer film,
and the end face of said insulator layer is in direct contact with
each of said electrode layers or is separated from each of said
electrode layers by a layer.
48. A magnetoresistive-effect device according to claim 32, wherein
said multilayer film comprises a central sensitive region which
provides an excellent reproduction gain, exhibiting a substantial
magnetoresistive effect and insensitive regions which are formed on
both sides of said sensitive region, and provide a poor
reproduction gain, exhibiting no substantial magnetoresistive
effect, and wherein said electrode layers deposited on both sides
of said multilayer film extend over the insensitive regions of said
multilayer film.
49. A magnetoresistive-effect device according to claim 48, wherein
said sensitive region of said multilayer film is defined as a
region which results in an output equal to or greater than 50% of a
maximum reproduction output while said insensitive regions of said
multilayer film are defined as regions, formed on both sides of
said sensitive region, which result in an output smaller than 50%
of the maximum reproduction output, when the
magnetoresistive-effect device having the electrode layers
deposited on both sides only of said multilayer film scans a micro
track, having a signal recorded thereon, in the direction of a
track width.
50. A magnetoresistive-effect device according to claim 48, wherein
the width dimension of said sensitive region of said multilayer
film is equal to an optical track width.
51. A magnetoresistive-effect device according to claim 48, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
52. A magnetoresistive-effect device according to claim 48, wherein
the angle made between the surface of said multilayer film and the
end face of said electrode layer extending over said insensitive
region of said multilayer film is within a range of 25 degrees to
45 degrees.
53. A magnetoresistive-effect device according to claim 48, wherein
a protective layer is deposited, as a top layer, on top of said
multilayer film.
54. A magnetoresistive-effect device according to claim 48, wherein
an insulator layer is deposited between said electrode layers,
which are deposited above and on both sides of said multilayer
film, and the end face of said insulator layer is in direct contact
with each of said electrode layers or is separated from each of
said electrode layers by a layer.
55. A magnetoresistive-effect device according to claim 53, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
56. A magnetoresistive-effect device according to claim 53, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 25 degrees to 45 degrees.
57. A magnetoresistive-effect device according to claim 54, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 60 degrees or
greater.
58. A magnetoresistive-effect device according to claim 54, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 90 degrees or
greater.
59. A magnetoresistive-effect device according to claim 54, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is equal to the width dimension of said
insensitive region of said multilayer film.
60. A magnetoresistive-effect device according to claim 32, wherein
an intermediate layer, made of at least one of a high-resistivity
material having a resistance higher than that of said electrode
layer and an insulating material, is interposed between said hard
bias layer and said electrode layer.
61. A magnetoresistive-effect device according to claim 60, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of TaSiO.sub.2, TaSi, CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and
TaN.
62. A magnetoresistive-effect device according to claim 60, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of Al.sub.2O.sub.3, SiO.sub.2, Ti.sub.2O.sub.3, TiO, WO, AlN,
Si.sub.3N.sub.4, B.sub.4C, SiC, and SiAlON.
63. A magnetoresistive-effect device comprising a multilayer film
comprising a magnetoresistive-effect layer, a soft magnetic layer,
and a nonmagnetic layer with said magnetoresistive-effect layer and
said soft magnetic layer laminated with said nonmagnetic layer
interposed therebetween, a pair of hard bias layers deposited on
both sides of said multilayer film, and a pair of electrode layers
respectively deposited on said hard bias layers, wherein said
electrode layers extend over said multilayer film.
64. A magnetoresistive-effect device according to claim 63, wherein
the position of at least one of the top edge and the bottom edge of
the magnetic coupling junction between said multilayer film and
said bias layer in the direction of the movement of a medium is at
the same level as the position of at least one of the top surface
and the bottom surface of said free magnetic layer or said
magnetoresistive layer in the direction of the movement of the
medium.
65. A magnetoresistive-effect device according to claim 63, wherein
a protective layer is deposited, as a top layer, on top of said
multilayer film.
66. A magnetoresistive-effect device according to claim 65, wherein
said protective layer is deposited where there is no junction
between said multilayer film and said electrode layer.
67. A magnetoresistive-effect device according to claim 63, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is within a range from 0 .mu.m to 0.08
.mu.m.
68. A magnetoresistive-effect device according to claim 67, wherein
the width dimension of the portion of each electrode layer
extending over said multilayer film is equal to or larger than 0.05
.mu.m.
69. A magnetoresistive-effect device according to claim 63, wherein
an insulator layer is deposited between said electrode
layers,-which are deposited above and on both sides of said
multilayer film, and the end face of said insulator layer is in
direct contact with each of said electrode layers or is separated
from each of said electrode layers by a layer.
70. A magnetoresistive-effect device according to claim 63, wherein
said multilayer film comprises a central sensitive region which
provides an excellent reproduction gain, exhibiting a substantial
magnetoresistive effect and insensitive regions which are formed on
both sides of said sensitive region, and provide a poor
reproduction gain, exhibiting no substantial magnetoresistive
effect, and wherein said electrode layers deposited on both sides
of said multilayer film extend over the insensitive regions of said
multilayer film.
71. A magnetoresistive-effect device according to claim 63, wherein
said sensitive region of said multilayer film is defined as a
region which results in an output equal to or greater than 50% of a
maximum reproduction output while said insensitive regions of said
multilayer film are defined as regions, formed on both sides of
said sensitive region, which result in an output smaller than 50%
of the maximum reproduction output, when the
magnetoresistive-effect device having the electrode layers
deposited on both sides only of said multilayer film scans a micro
track, having a signal recorded thereon, in the direction of a
track width.
72. A magnetoresistive-effect device according to claim 63, wherein
the width dimension of said sensitive region of said multilayer
film is equal to an optical track width.
73. A magnetoresistive-effect device according to claim 63, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
74. A magnetoresistive-effect device according to claim 63, wherein
the angle made between the surface of said multilayer film and the
end face of said electrode layer extending over said insensitive
region of said multilayer film is within a range of 25 degrees to
45 degrees.
75. A magnetoresistive-effect device according to claim 65, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 20 degrees to 60 degrees.
76. A magnetoresistive-effect device according to claim 65, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is within a range
of 25 degrees to 45 degrees.
77. A magnetoresistive-effect device according to claim 69, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 60 degrees or
greater.
78. A magnetoresistive-effect device according to claim 69, wherein
the angle made between the surface of said protective layer or the
surface of said multilayer film with said protective layer removed
therefrom and the end face of said electrode layer extending over
said insensitive region of said multilayer film is 90 degrees or
greater.
79. A magnetoresistive-effect device according to claim 69, wherein
the width dimension of a portion of each electrode layer extending
over said multilayer film is equal to the width dimension of said
insensitive region of said multilayer film.
80. A magnetoresistive-effect device according to claim 63, wherein
an intermediate layer, made of at least one of a high-resistivity
material having a resistance higher than that of said electrode
layer and an insulating material, is interposed between said hard
bias layer and said electrode layer.
81. A magnetoresistive-effect device according to claim 80, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of TaSiO.sub.2, TaSi, CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and
TaN.
82. A magnetoresistive-effect device according to claim 80, wherein
said high-resistivity material, which fabricates said intermediate
layer interposed between said hard bias layer and said electrode
layer, is at least one material selected from the group consisting
of Al.sub.2O.sub.3, SiO.sub.2, Ti.sub.2O.sub.3, TiO, WO, AlN,
Si.sub.3N.sub.4, B.sub.4C, SiC, and SiAlON.
83. A method for manufacturing a magnetoresistive-effect device
comprising the steps of: laminating, on a substrate, a multilayer
film for exhibiting the magnetoresistive effect; depositing, on a
sensitive region of said multilayer film, a lift-off resist layer
having an undercut on the underside thereof facing insensitive
regions of said multilayer film, wherein said sensitive region and
said insensitive regions are beforehand measured through a micro
track profile method; depositing bias layers on both sides of said
multilayer film and magnetizing said bias layers in the direction
of a track width; depositing an electrode layer on the said bias
layer at a slant angle with respect to said multilayer film,
wherein said electrode layer is deposited into the undercut on the
underside of said resist layer arranged on said multilayer film;
and removing said resist layer from said multilayer film.
84. A method for manufacturing a magnetoresistive-effect device
according to claim 83, comprising depositing a protective layer as
a top layer on said multilayer film in the step of laminating, on
the substrate, said multilayer film for exhibiting the
magnetoresistive effect; depositing said lift-off resist layer on
top of said protective layer in the sensitive region of said
multilayer film, in the step of depositing said lift-off resist
layer on the sensitive region of said multilayer film; and exposing
the underlayer beneath said protective layer by removing a portion
of said protective layer which is not in direct contact with said
lift-off resist layer.
85. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein the step of depositing said
electrode layer sets, to be within a range of 20 degrees to 60
degrees, the angle made between the surface of said protective
layer or the surface of said multilayer film with said protective
layer removed therefrom and the end face of said electrode layer
extending over said insensitive region of said multilayer film.
86. A method for manufacturing a magnetoresistive-effect device
according to claim 85, wherein the step of depositing said
electrode layer sets, to be within a range of 25 degrees to 45
degrees, the angle made between the surface of said protective
layer or the surface of said multilayer film with said protective
layer removed therefrom and the end face of said electrode layer
extending over said insensitive region of said multilayer film.
87. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said sensitive region of said
multilayer film, measured through a micro track profile method, is
defined as a region which results in an output equal to or greater
than 50% of a maximum reproduction output while said insensitive
regions of said multilayer film are defined as regions, formed on
both sides of said sensitive region, which result in an output
smaller than 50% of the maximum reproduction output, when a
magnetoresistive-effect device having the electrode layers
deposited on hard bias layers only and not extending over said
multilayer film scans a micro track, having a signal recorded
thereon, in the direction of a track width.
88. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said bias layers are deposited on
both sides of said multilayer film through at least one sputtering
technique selected from an ion-beam sputtering method, a long-throw
sputtering method, and a collimation sputtering method, with said
substrate, having said multilayer film thereon, placed normal to a
target made of a composition of said bias layer; and said electrode
layer is deposited on said bias layer into an undercut formed in
the underside of said resist layer arranged on said multilayer
film, through at least one sputtering technique selected from an
ion beam sputtering method, a long-throw sputtering method, and a
collimation sputtering method with said substrate, having said
multilayer film thereon, placed slightly oblique to a target made
of a composition of said electrode layer, or with the target placed
slightly oblique to the substrate.
89. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said multilayer film comprises an
antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic
electrically conductive layer, and a free magnetic layer, or said
multilayer film comprises a free magnetic layer, nonmagnetic
electrically conductive layers respectively lying over and under
said free magnetic layer, pinned magnetic layers respectively lying
over said one nonmagnetic electrically conductive layer and under
said other nonmagnetic electrically conductive layer, and
antiferromagnetic layers respectively lying over said one pinned
magnetic layer and under said other pinned magnetic layer, or said
multilayer film comprises a magnetoresistive-effect layer, a soft
magnetic layer, and a nonmagnetic layer wherein said
magnetoresistive-effect layer and said soft magnetic layer are
laminated with said nonmagnetic layer interposed therebetween.
90. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said multilayer film comprises at
least one of each of an antiferromagnetic layer, a pinned magnetic
layer, a nonmagnetic electrically conductive layer, and a free
magnetic layer, or said multilayer film comprises a free magnetic
layer, nonmagnetic electrically conductive layers respectively
lying over and under said free magnetic layer, pinned magnetic
layers respectively lying over said one nonmagnetic electrically
conductive layer and under said other nonmagnetic electrically
conductive layer, and antiferromagnetic layers respectively lying
over said one pinned magnetic layer and under said other pinned
magnetic layer, or said multilayer film comprises a
magnetoresistive-effect layer, a soft magnetic layer, and a
nonmagnetic layer wherein said magnetoresistive-effect layer and
said soft magnetic layer are laminated with said nonmagnetic layer
interposed therebetween.
91. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said free magnetic layer comprises a
plurality of soft magnetic thin films having different magnetic
moments and nonmagnetic material layers, which are alternatively
laminated with one soft magnetic thin film separated from another
by one nonmagnetic material layer, and said free magnetic layer is
in a ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
92. A method for manufacturing a magnetoresistive-effect device
according to claim 91, wherein, in the step of depositing said bias
layers, the magnetic coupling junction between said multilayer film
and said bias layer is fabricated of an interface with the end face
of only one of the plurality of the soft magnetic thin films
forming said free magnetic layer.
93. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein said pinned magnetic layer comprises
a plurality of soft magnetic thin films having different magnetic
moments and nonmagnetic material layers, which are alternately
laminated with one soft magnetic thin film separated from another
by one nonmagnetic material layer, and said pinned magnetic layer
is in a ferrimagnetic state in which the magnetization directions
of adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
94. A method for manufacturing a magnetoresistive-effect device
according to claim 91, wherein said nonmagnetic material layer is
made of a material selected from the group consisting of Ru, Rh,
Ir, Cr, Re, Cu, and alloys thereof.
95. A method for manufacturing a magnetoresistive-effect device
according to claim 83, wherein in the step of depositing said bias
layers, the position of at least one of the top edge and the bottom
edge of the magnetic coupling junction between said multilayer film
and said bias layer in the direction of the movement of a medium is
set to be at the same level as the position of at least one of the
top surface and the bottom surface of said free magnetic layer or
said magnetoresistive-effect layer in the direction of the movement
of the medium.
96. A method for manufacturing a magnetoresistive-effect device
according to claim 89, wherein said antiferromagnetic layer is made
of a PtMn alloy.
97. A method for manufacturing a magnetoresistive-effect device
according to claim 89, wherein said antiferromagnetic layer is made
of an X--Mn alloy where X is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof.
98. A method for manufacturing a magnetoresistive-effect device
according to claim 89, wherein said antiferromagnetic material is
made of a Pt--Mn--X' alloy where X' is a material selected from the
group consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
99. A method for manufacturing a magnetoresistive-effect device
comprising the steps of: laminating, on a substrate, a multilayer
film for exhibiting the magnetoresistive effect; depositing an
insulator layer on said multilayer film; depositing, on said
insulator layer in a sensitive region of said multilayer film, a
lift-off resist layer having an undercut on the underside thereof
facing insensitive regions of said multilayer film, wherein said
sensitive region and said insensitive regions are beforehand
measured through a micro track profile method; removing said
insulator layer deep to said undercut formed on the underside of
said resist layer, through etching; depositing bias layers on both
sides of said multilayer film and magnetizing said bias layers in
the direction of a track width; depositing an electrode layer on
the said bias layer at a slant angle with respect to said
multilayer film, wherein said electrode layer is deposited on and
in direct contact with an end face of said insulator layer, which
is the underlayer beneath said resist layer, or is formed to be
separated from the end face of said insulator layer by a layer; and
removing said resist layer from said insulator layer.
100. A method for manufacturing a magnetoresistive-effect device
according to claim 99, comprising depositing a protective layer as
a top layer on said multilayer film in the step of laminating, on
the substrate, said multilayer film for exhibiting the
magnetoresistive effect; and removing the area of said protective
layer not covered with said insulator layer to expose the
underlayer beneath said protective layer, subsequent to the
removing step of removing said insulator layer deep to said
undercut formed on the underside of said resist layer, through
etching.
101. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein in the step of depositing said
electrode layer, the angle made between the surface of said
protective layer or the surface of said multilayer film with said
protective layer removed therefrom and the end face of said
electrode layer extending over said insensitive region of said
multilayer film is 60 degrees or greater.
102. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein in the step of depositing said
electrode layer, the angle made between the surface of said
protective layer or the surface of said multilayer film with said
protective layer removed therefrom and the end face of said
electrode layer extending over said insensitive region of said
multilayer film is 90 degrees or greater.
103. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said sensitive region of said
multilayer film, measured through a micro track profile method, is
defined as a region which results in an output equal to or greater
than 50% of a maximum reproduction output while said insensitive
regions of said multilayer film are defined as regions, formed on
both sides of said sensitive region, which result in an output
smaller than 50% of the maximum reproduction output, when a
magnetoresistive-effect device having the electrode layers
deposited on hard bias layers and not extending over said
multilayer film scans a micro track, having a signal recorded
thereon, in the direction of a track width.
104. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said bias layers are deposited on
both sides of said multilayer film through at least one sputtering
technique selected from an ion-beam sputtering method, a long-throw
sputtering method, and a collimation sputtering method, with said
substrate, having said multilayer film thereon, placed normal to a
target made of a composition of said bias layer; and said electrode
layer is deposited on said bias layer into an undercut formed in
the underside of said resist layer arranged on said multilayer
film, through at least one sputtering technique selected from an
ion beam sputtering method, a long-throw sputtering method, and a
collimation sputtering method, with said substrate having said
multilayer film thereon, placed slightly oblique to a target made
of a composition of said electrode layer, or with the target placed
slightly oblique to the substrate.
105. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said multilayer film comprises an
antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic
electrically conductive layer, and a free magnetic layer, or said
multilayer film comprises a free magnetic layer, nonmagnetic
electrically conductive layers respectively lying over and under
said free magnetic layer, pinned magnetic layer respectively lying
over said one nonmagnetic electrically conductive layer and under
said other nonmagnetic electrically conductive layer, and
antiferromagnetic layers respectively lying over said one pinned
magnetic layer and under said other pinned magnetic layer, or said
multilayer film comprises a magnetoresistive-effect layer, a soft
magnetic layer, and a nonmagnetic layer wherein said
magnetoresistive-effect layer and said soft magnetic layer are
laminated with said nonmagnetic layer interposed therebetween.
106. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said multilayer film comprises at
least one of each of an antiferromagnetic layer, a pinned magnetic
layer, a nonmagnetic electrically conductive layer, and a free
magnetic layer, or said multilayer film comprises a free magnetic
layer, nonmagnetic electrically conductive layers respectively
lying over and under said free magnetic layer, pinned magnetic
layers respectively lying over said one nonmagnetic electrically
conductive layer and under said other nonmagnetic electrically
conductive layer, and antiferromagnetic layers respectively lying
over said one pinned magnetic layer and under said other pinned
magnetic layer, or said multilayer film comprises a
magnetoresistive-effect layer, a soft magnetic layer, and a
nonmagnetic layer wherein said magnetoresistive-effect layer and
said soft magnetic layer are laminated with said nonmagnetic layer
interposed therebetween.
107. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said free magnetic layer comprises a
plurality of soft magnetic thin films having different magnetic
moments and nonmagnetic material layers, which are alternately
laminated with one soft magnetic thin film separated from another
by one nonmagnetic material layer, and said free magnetic layer is
in a ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
108. A method for manufacturing a magnetoresistive-effect device
according to claim 107, wherein, in the step of depositing said
bias layers, the magnetic coupling junction between said multilayer
film and said bias layer is fabricated of an interface with the end
face of only one of the plurality of the soft magnetic thin films
forming said free magnetic layer.
109. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein said pinned magnetic layer comprises
a plurality of soft magnetic thin films having different magnetic
moments and nonmagnetic material layers, which are alternately
laminated with one soft magnetic thin film separated from another
by one nonmagnetic material layer, and said pinned magnetic layer
is in a ferrimagnetic state in which the magnetization directions
of adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
110. A method for manufacturing a magnetoresistive-effect device
according to claim 107, wherein said nonmagnetic material layer is
made of a material selected from the group consisting of Ru, Rh,
Ir, Cr, Re, Cu, and alloys thereof.
111. A method for manufacturing a magnetoresistive-effect device
according to claim 99, wherein in the step of depositing said bias
layers, the position of at least one of the top edge and the bottom
edge of the magnetic coupling junction between said multilayer film
and said bias layer in the direction of the movement of a medium is
set to be at the same level as the position of at least one of the
top surface and the bottom surface of said free magnetic layer or
said magnetoresistive-effect layer in the direction of the movement
of the medium.
112. A method for manufacturing a magnetoresistive-effect device
according to claim 105, wherein said antiferromagnetic layer is
made of a PtMn alloy.
113. A method for manufacturing a magnetoresistive-effect device
according to claim 105, wherein said antiferromagnetic layer is
made of an X--Mn alloy where X is a material selected from the
group consisting of Pd, Ir, Rh, Ru, and alloys thereof.
114. A method for manufacturing a magnetoresistive-effect device
according to claim 105, wherein said antiferromagnetic material is
made of a Pt--Mn--X' alloy where X' is a material selected from the
group consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a so-called spin-valve type
thin-film device, in which an electrical resistance thereof varies
depending on the relationship between the magnetization direction
of a pinned magnetic layer and the magnetization direction of a
free magnetic layer which is affected by external magnetic field,
and, more particularly, to a magnetoresistive-effect device that
allows a sense current to effectively flow through a multilayer
film and a method for manufacturing the magnetoresistive-effect
device.
[0003] 2. Description of the Related Art
[0004] FIG. 33 is a cross-sectional view showing the construction
of a conventional magnetoresistive-effect device, viewed from an
ABS (air bearing surface) side thereof.
[0005] The magnetoresistive-effect device shown in FIG. 33 is the
one called a spin-valve type thin-film device, one of the GMR
(giant magnetoresistive) devices employing the giant
magnetoresistive effect, and detects a magnetic field recorded on a
recording medium, such as a hard disk.
[0006] This spin-valve type thin-film device includes a multilayer
film 9 including a substrate 6, an antiferromagnetic layer 1, a
pinned magnetic layer 2, a nonmagnetic electrically conductive 3, a
free magnetic layer 4, and a protective layer 7, a pair of hard
bias layers 5, and a pair of electrode layers 8 and 8 respectively
deposited on the hard bias layers 5 and 5, deposited on both sides
of the multilayer film 9. The substrate 6 and the protective layer
7 are made of Ta (tantalum). A track width Tw is determined by the
width dimension of the top surface of the multilayer film 9.
[0007] The antiferromagnetic layer 1 is typically an Fe--Mn
(iron-manganese) alloy film or an Ni--Mn (nickel-manganese) alloy
film, the pinned magnetic layer 2 and the free magnetic layer 4 are
typically an Ni--Fe (nickel-iron) alloy film, the nonmagnetic
electrically conductive layer 3 is typically a Cu (copper) film,
the hard bias layers 5 and 5 are typically Co--Pt (cobalt-platinum)
alloy films, and the electrode layers 8 and 8 are typically Cr
(chromium) films.
[0008] Referring to FIG. 33, the magnetization of the pinned
magnetic layer 2 is placed into a single-domain state in the Y
direction (i.e., the direction of a leakage magnetic field from a
recording medium, namely, the direction of the height of the
multilayer film from the recording medium), and the magnetization
of the free magnetic layer 4 is oriented in the X direction under
the influence of a bias magnetic field of the hard bias layers
5.
[0009] The magnetization of the pinned magnetic layer 2 is designed
to be perpendicular to the magnetization of the free magnetic layer
4.
[0010] In this spin-valve type thin-film device, the electrode
layers 8 and 8, deposited on the hard bias layers 5 and 5, feed
sense currents to the pinned magnetic layer 2, the nonmagnetic
electrically conductive layer 3 and the free magnetic layer 4. The
direction of the advance of the recording medium, such as a hard
disk, is aligned with the Z direction. When a leakage magnetic
field is given by the recording medium in the Y direction, the
magnetization of the free magnetic layer 4 varies from the X
direction toward the Y direction. An electric resistance varies
depending on the relationship between a variation in the
magnetization direction within the free magnetic layer 4 and a
pinned magnetization direction of the pinned magnetic layer 2 (this
phenomenon is called the magnetoresistive effect), and the leakage
magnetic field is sensed from the recording medium based on a
variation in the voltage in response to the variation in the
electrical resistance.
[0011] The magnetoresistive-effect device shown in FIG. 33 suffers
from the following problems.
[0012] The magnetization of the pinned magnetic layer 2 is pinned
in a single-domain state in the Y direction, and the hard bias
layers 5 and 5, magnetized in the X direction, are arranged on both
sides of the pinned magnetic layer 2. The magnetization of the
pinned magnetic layer 2 on both ends is therefore affected by the
bias magnetic field from the hard bias layers 5 and 5, and is thus
not pinned in the Y direction.
[0013] Specifically, the magnetization of the free magnetic layer 4
in the X direction single-domain state and the magnetization of the
pinned magnetic layer 2 are not in a perpendicular relationship,
particularly on end portions of the multilayer film 9, under the
influence of the X direction magnetization of the hard bias layers
5 and 5. The magnetization of the free magnetic layer 4 is set to
be perpendicular to the magnetization of the pinned magnetic layer
2 because the magnetization of the free magnetic layer 4 is easily
varied in response to a weak external magnetic field, causing the
electric resistance to greatly vary, and thereby enhancing
reproduction gain. Furthermore, the perpendicular relationship
results in output waveforms having a good symmetry.
[0014] Since the magnetization of the free magnetic layer 4 on end
portions thereof is likely to be pinned under the influence of a
strong magnetization of the hard bias layers 5 and 5, the
magnetization of the free magnetic layer 4 less varies in response
to an external magnetic field. As shown in FIG. 33, insensitive
regions having a poor reproduction gain is formed in the end
regions of the multilayer film 9.
[0015] A central portion other than the insensitive regions, of the
multilayer film 9, substantially contributes to the reproduction of
the recorded magnetic field, and is thus a sensitive region
exhibiting the magnetoresistive effect. The width of the sensitive
region is narrower than a track width Tw defined in the formation
of the multilayer film 9 by the width dimension of the insensitive
regions.
[0016] The multilayer film 9 of the magnetoresistive-effect device
on both end portions thereof is thus associated with the
insensitive regions that contribute nothing to the reproduction
output, and these insensitive regions merely increases a direct
current resistance (DCR).
[0017] In the magnetoresistive-effect device having the
construction in which the electrode layers 8 and 8 are deposited on
only both sides of the multilayer film 9 as shown in FIG. 33, the
sense current from the electrode layers 8 and 8 easily flows into
the hard bias layers 5 and 5, reducing the percentage of the
current flowing into the multilayer film 9. The presence of the
insensitive regions further substantially reduces the quantity of
the sense current flowing into the sensitive region. The
conventional magnetoresistive-effect device cannot feed an
effective sense current to the sensitive region, and suffers from a
drop in the reproduction output as the direct current resistance
increases.
SUMMARY OF THE INVENTION
[0018] Accordingly, it is an object of the present invention to
provide a magnetoresistive-effect device which reduces a direct
current resistance by overlapping an electrode layer over an
insensitive region of a multilayer film to improve reproduction
characteristics, and a method for manufacturing the
magnetoresistive-effect device.
[0019] According to a first aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
an antiferromagnetic layer, a pinned magnetic layer, which is
deposited on and in contact with the antiferromagnetic layer, and
the magnetization direction of which is pinned through an exchange
anisotropic magnetic field with the antiferromagnetic layer, and a
free magnetic layer, separated from the pinned magnetic layer by a
nonmagnetic electrically conductive layer, a pair of hard bias
layers, deposited on both sides of the multilayer film, for
orienting the magnetization direction of the free magnetic layer
perpendicular to the magnetization direction of the pinned magnetic
layer, and a pair of electrode layers respectively deposited on the
hard bias layers, wherein the electrode layers extend over the
multilayer film.
[0020] Preferably, the first magnetoresistive-effect device
includes the multilayer film including the antiferromagnetic layer,
the pinned magnetic layer, which is deposited on and in contact
with the antiferromagnetic layer, and the magnetization direction
of which is pinned through an exchange anisotropic magnetic field
with the antiferromagnetic layer, and the free magnetic layer,
separated from the pinned magnetic layer by the nonmagnetic
electrically conductive layer, the pair of hard bias layers,
deposited on both sides of the multilayer film, for orienting the
magnetization direction of the free magnetic layer perpendicular to
the magnetization direction of the pinned magnetic layer, and the
pair of electrode layers respectively deposited on the hard bias
layers, for feeding a sense current to the pinned magnetic layer,
the nonmagnetic electrically conductive layer, and the free
magnetic layer, wherein the multilayer film includes a central
sensitive region which provides an excellent reproduction gain,
exhibiting a substantial magnetoresistive effect and insensitive
regions which are formed on both sides of the sensitive region, and
provide a poor reproduction gain, exhibiting no substantial
magnetoresistive effect, and wherein the electrode layers deposited
on both sides of the multilayer film extend over the insensitive
regions of the multilayer film.
[0021] Preferably, the multilayer film is fabricated by
successively laminating the antiferromagnetic layer, the pinned
magnetic layer, the nonmagnetic electrically conductive layer, and
the free magnetic layer in that order from below, the
antiferromagnetic layer laterally extends from the layers laminated
thereon, and a pair of hard bias layer, a pair of intermediate
layers, and a pair of electrode layers are respectively laminated
on a pair of metallic layers respectively deposited on the
antiferromagnetic layers in laterally extending regions
thereof.
[0022] According to a second aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
a free magnetic layer, nonmagnetic electrically conductive layer
respectively lying over and under the free magnetic layer, pinned
magnetic layers respectively lying over the one nonmagnetic
electrically conductive layer and under the other nonmagnetic
electrically conductive layer, each having a pinned magnetization
direction, and antiferromagnetic layers respectively lying over the
one pinned magnetic layer and under the other pinned magnetic
layer, and a pair of hard bias layers, formed on both sides of the
multilayer film, for orienting the magnetization direction of the
free magnetic layer perpendicular to the magnetization direction of
the pinned magnetic layer, and a pair of electrode layers
respectively deposited on the hard bias layers, wherein the
electrode layers extend over the multilayer film.
[0023] Preferably, the magnetoresistive-effect device includes the
multilayer film including the free magnetic layer, nonmagnetic
electrically conductive layers respectively lying over and under
the free magnetic layer, pinned magnetic layers respectively lying
over the one nonmagnetic electrically conductive layer and under
the other nonmagnetic electrically conductive layer, each having a
pinned magnetization direction, and antiferromagnetic layers
respectively lying over the one pinned magnetic layer and under the
other pinned magnetic layer, and the pair of hard bias layers,
deposited on both sides of the multilayer film, for orienting the
magnetization direction of the free magnetic layer perpendicular to
the magnetization direction of the pinned magnetic layer, and the
pair of electrode layers deposited on the hard bias layers, for
feeding a sense current to the pinned magnetic layer, the
nonmagnetic electrically conductive layer, and the free magnetic
layer, wherein the multilayer film includes a central sensitive
region which provides an excellent reproduction gain, exhibiting a
substantial magnetoresistive effect and insensitive regions which
are formed on both sides of the sensitive region, and provide a
poor reproduction gain, exhibiting no substantial magnetoresistive
effect, and wherein the electrode layers deposited on both sides of
the multilayer film extend over the insensitive regions of the
multilayer film.
[0024] Preferably, the free magnetic layer includes a plurality of
soft magnetic thin films having different magnetic moments and
nonmagnetic material layers, which are alternately laminated with
one soft magnetic thin film separated from another by one
nonmagnetic material layer, and the free magnetic layer is in a
ferrimagnetic state in which the magnetization directions of two
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other. This
arrangement offers the same result as the one obtained from the use
of a thin free magnetic layer. The magnetization of the free
magnetic layer is easily varied, improving the magnetic field
detection sensitivity of the magnetoresistive-effect device.
[0025] The magnitude of the magnetic moment of the soft magnetic
thin film is the product of the saturation magnetization (Ms) and
the film thickness (t) of the soft magnetic thin film.
[0026] When the free magnetic layer is fabricated by alternately
laminating a plurality of soft magnetic thin films having different
magnetic moments and nonmagnetic material layers, the magnetization
directions of two adjacent soft magnetic thin films, separated by
the nonmagnetic material layer, are aligned antiparallel to each
other in a ferrimagnetic state. With this arrangement, the
plurality of the soft magnetic thin films alternate between the one
having magnetization thereof aligned in the direction of a magnetic
field generated from the bias layer and the one having
magnetization thereof in 180 degrees opposite direction from the
direction of the magnetic field of the bias layer.
[0027] The soft magnetic thin film having a magnetization direction
thereof 180 degrees opposite from the direction of the magnetic
field of the bias layer is subject to disturbance in magnetization
direction on both end portions magnetically coupled with the bias
layer. The soft magnetic thin film, separated from the above soft
magnetic thin film by the nonmagnetic material layer, and having a
magnetization direction thereof aligned with the direction of the
magnetic field of the bias layer, is disturbed along therewith in
magnetization direction on both end portions.
[0028] Both end portions where the soft magnetic thin films
constituting the free magnetic field are disturbed in magnetization
direction become insensitive regions which present a poor
reproduction gain and exhibit no substantial magnetoresistive
effect. In the present invention, the electrode layers are formed
to extend over the insensitive regions.
[0029] When the free magnetic layer is fabricated by alternately
laminating a plurality of soft magnetic thin films having different
magnetic moments and nonmagnetic material layers with one
nonmagnetic layer interposed between two adjacent soft magnetic
thin films, the magnetic coupling junction between the multilayer
film and the bias layer is preferably fabricated of an interface of
the bias layer with the end face of only one of the plurality of
the soft magnetic thin films forming the free magnetic layer.
[0030] It is sufficient if the bias layer aligns the magnetization
direction of one of the plurality of the soft magnetic thin films
constituting the free magnetic layer. When the magnetization
direction of the one soft magnetic thin film is aligned in one
direction, another soft magnetic thin film next to the first soft
magnetic thin film is shifted to a ferrimagnetic state with a
magnetization direction thereof aligned antiparallel. Consequently,
all soft magnetic thin films are alternately aligned parallel to
and antiparallel to one direction, and the magnetization direction
of the entire free magnetic layer is aligned in one direction.
[0031] If the bias layer is magnetically coupled with the plurality
of the soft magnetic thin films constituting the free magnetic
layer, the magnetization direction of the soft magnetic thin films
is undesirably disturbed on both end portions.
[0032] The pinned magnetic layer is fabricated by alternately
laminating a plurality of soft magnetic thin films having different
magnetic moments and nonmagnetic material layers with one
nonmagnetic layer interposed between two adjacent soft magnetic
thin films. When the magnetization direction of one soft magnetic
thin film, separated from another soft magnetic thin film by the
nonmagnetic material layer, is in a ferrimagnetic state with a
magnetization direction thereof aligned antiparallel, the plurality
of the soft magnetic thin films constituting the pinned magnetic
layer mutually pin each other. As a result, the magnetization
direction of the pinned magnetic layer is advantageously stabilized
in one direction.
[0033] Here again, the magnitude of the magnetic moment of the soft
magnetic thin film is the product of the saturation magnetization
(Ms) and the film thickness (t) of the soft magnetic thin film.
[0034] The nonmagnetic material layer is preferably made of a
material selected from the group consisting of Ru, Rh, Ir, Cr, Re,
Cu, and alloys thereof.
[0035] The antiferromagnetic layer is preferably made of a PtMn
alloy. Alternatively, the antiferromagnetic layer may be made of an
X--Mn alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof, or may be made of
a Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0036] According to a third aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
a magnetoresistive-effect layer, a soft magnetic layer, and a
nonmagnetic layer with the magnetoresistive-effect layer and the
soft magnetic layer laminated with the nonmagnetic layer interposed
therebetween, a pair of hard bias layers deposited on both sides of
the multilayer film, and a pair of electrode layers respectively
deposited on the hard bias layers, wherein the electrode layers
extend over the multilayer film.
[0037] Preferably, the magnetoresistive-effect device preferably
includes the multilayer film including the magnetoresistive-effect
layer, the soft magnetic layer, and the nonmagnetic layer with the
magnetoresistive-effect layer and the soft magnetic layer laminated
with the nonmagnetic layer interposed therebetween, the pair of
hard bias layers deposited on both sides of the multilayer film,
and the pair of electrode layers respectively deposited on the hard
bias layers, wherein the multilayer film includes a central
sensitive region which provides an excellent reproduction gain,
exhibiting a substantial magnetoresistive effect and insensitive
regions which are formed on both sides of the sensitive region, and
provide a poor reproduction gain, exhibiting no substantial
magnetoresistive effect, and wherein the electrode layers deposited
on both sides of the multilayer film extend over the insensitive
regions of the multilayer film.
[0038] Preferably, the position of at least one of the top edge and
the bottom edge of the magnetic coupling junction between the
multilayer film and the bias layer in the direction of the movement
of a medium is at the same level as the position of at least one of
the top surface and the bottom surface of the free magnetic layer
or the magnetoresistive-effect layer in the direction of the
movement of the medium.
[0039] Preferably, the bias layer is magnetically coupled, directly
or via another intervening layer as an underlayer, with the
multilayer film on the side face thereof transverse to the
direction of a track width. The bias layer functions to align the
magnetization direction of the free magnetic layer or the
magnetoresistive-effect layer, out of the multilayer film, in one
direction. It is therefore sufficient if the bias layer is
magnetically coupled with the free magnetic layer only or the
magnetoresistive-effect layer only. To prevent the magnetic field
generated from the bias layer from affecting the magnetization
direction of the pinned magnetic layer, the bias layer preferably
remains magnetically uncoupled with the pinned magnetic layer.
[0040] A protective layer, constructed of Ta, etc., is preferably
deposited, as a top layer, on top of the multilayer film to prevent
oxidation.
[0041] An electrode layer, if laminated on the protective layer,
adversely affects the characteristics of the
magnetoresistive-effect device, for example, increases an
electrical resistance. Therefore, the protective layer is
preferably deposited where there is no junction between the
multilayer film and the electrode layer.
[0042] The sensitive region of the multilayer film is defined as a
region which results in an output equal to or greater than 50% of a
maximum reproduction output while the insensitive regions of the
multilayer film are defined as regions, formed on both sides of the
sensitive region, which result in an output smaller than 50% of the
maximum reproduction output, when the magnetoresistive-effect
device having the electrode layers on both sides only of the
multilayer film scans a micro track, having a signal recorded
thereon, in the direction of a track width.
[0043] The width dimension of the sensitive region of the
multilayer film is preferably equal to an optical track width
O-Tw.
[0044] The width dimension of a portion of each electrode layer
extending over the multilayer film is preferably within a range
from 0 .mu.m to 0.08 .mu.m.
[0045] The width dimension of the portion of each electrode layer
extending over the multilayer film is preferably equal to or larger
than 0.05 .mu.m.
[0046] The angle made between the surface of the protective layer
or the surface of the multilayer film with the protective layer
removed therefrom and the end face of the electrode layer extending
over the insensitive region of the multilayer film is preferably
within a range of 20 degrees to 60 degrees, and more preferably
within a range of 25 degrees to 45 degrees.
[0047] An insulator layer is preferably deposited between the
electrode layers, which are deposited above and on both sides of
the multilayer film, and the end face of the insulator layer is in
direct contact with each of the electrode layers or is separated
from each of the electrode layers by a layer.
[0048] The angle made between the surface of the protective layer
or the surface of the multilayer film with the protective layer
removed therefrom and the end face of the electrode layer extending
over the insensitive region of the multilayer film is preferably 60
degrees or greater, and more preferably 90 degrees or greater.
[0049] The width dimension of a portion of each electrode layer
extending over the multilayer film is preferably substantially
equal to the width dimension of the insensitive region of the
multilayer film.
[0050] According to a fourth aspect of the present invention, a
method for manufacturing a magnetoresistive-effect device includes
the steps of laminating, on a substrate, a multilayer film for
exhibiting the magnetoresistive effect, depositing, on a sensitive
region of the multilayer film, a lift-off resist layer having an
undercut on the underside thereof facing insensitive regions of the
multilayer film with the sensitive and insensitive regions
beforehand measured through a micro track profile method,
depositing bias layers on both sides of the multilayer film and
magnetizing the bias layer in the direction of a track width,
depositing an electrode layer on the bias layer at a slant angle
with respect to the multilayer film, with the electrode layer
formed into the undercut on the underside of the resist layer
arranged on the multilayer film, and removing the resist layer from
the multilayer film.
[0051] When a protective layer is deposited as a top layer on the
multilayer film for oxidation prevention in the step of laminating,
on the substrate, the multilayer film for exhibiting the
magnetoresistive effect, the method preferably includes the steps
of depositing the lift-off resist layer on top of the protective
layer in the sensitive region of the multilayer film, in the step
of depositing the lift-off resist layer on the sensitive region of
the multilayer film, and exposing the underlayer beneath the
protective layer by removing a portion of the protective layer
which is not in direct contact with the lift-off resist layer. In
this way, the electrode layer advantageously joins the multilayer
film where the protective layer having a high electrical resistance
is removed, when the electrode layer is deposited to extend over
the multilayer film.
[0052] In the step of depositing the electrode layer, the angle
made between the surface of the protective layer or the surface of
the multilayer film with the protective layer removed therefrom and
the end face of the electrode layer extending over the insensitive
region of the multilayer film is preferably within a range of 20
degrees to 60 degrees, and more preferably within a range of 25
degrees to 45 degrees.
[0053] According to a fifth aspect of the present invention, a
method for manufacturing a magnetoresistive-effect device includes
the steps of laminating, on a substrate, a multilayer film for
exhibiting the magnetoresistive effect, depositing an insulator
layer on the multilayer film, depositing, on the insulator layer in
a sensitive region of the multilayer film, a lift-off resist layer
having an undercut on the underside thereof facing insensitive
regions of the multilayer film with the insensitive regions
beforehand measured through a micro track profile method, removing
the insulator layer deep to the undercut formed on the underside of
the resist layer, through etching, depositing bias layers on both
sides of the multilayer film and magnetizing the bias layers in the
direction of a track width, depositing an electrode layer on the
bias layer at a slant angle with respect to the multilayer film,
with the electrode layer formed to be in direct contact with an end
face of the insulator layer, i.e., the underlayer beneath the
resist layer, or with the electrode layer formed to be separated
from the end face of the insulator layer by a layer, and removing
the resist layer from the insulator layer.
[0054] When a protective layer is deposited as a top layer on the
multilayer film for oxidation prevention in the step of depositing,
on the substrate, the multilayer film for exhibiting the
magnetoresistive effect, the method preferably includes the step of
removing the area of the protective layer not covered with the
insulator layer to expose the underlayer beneath the protective
layer, subsequent to the step of removing the insulator layer deep
to the undercut formed on the underside of the resist layer through
etching. In this way, the electrode layer advantageously joins the
multilayer film where the protective layer having a high electrical
resistance is removed, when the electrode layer is formed to extend
over the multilayer film.
[0055] In the method for manufacturing the magnetoresistive-effect
device including the step of laminating the insulator layer on the
multilayer film, in the step of forming the electrode layer, the
angle made between the surface of the protective layer or the
surface of the multilayer film with the protective layer removed
therefrom and the end face of the electrode layer extending over
the insensitive region of the multilayer film is preferably 60
degrees or greater, and more preferably 90 degrees or greater.
[0056] The sensitive region of the multilayer film, measured
through a micro track profile method, is defined as a region which
results in an output equal to or greater than 50% of a maximum
reproduction output while the insensitive regions of the multilayer
film are defined as regions, formed on both sides of the sensitive
region, which result in an output smaller than 50% of the maximum
reproduction output, when a magnetoresistive-effect device having
the electrode layers formed on hard bias layers only and not
extending over the multilayer film scans a micro track, having a
signal recorded thereon, in the direction of the track width.
[0057] In the method for manufacturing a magnetoresistive-effect
device, the bias layers are preferably deposited on both sides of
the multilayer film through at least one sputtering technique
selected from an ion-beam sputtering method, a long-throw
sputtering method, and a collimation sputtering method, with the
substrate, having the multilayer film thereon, placed perpendicular
to a target made of a composition of the bias layer, and the
electrode layer is preferably deposited on the bias layer into an
undercut formed in the underside of the resist layer arranged on
the multilayer film through at least one sputtering technique
selected from an ion beam sputtering method, a long-throw
sputtering method, and a collimation sputtering method, with the
substrate, having the multilayer film thereon, placed slightly
oblique to a target made of a composition of the electrode layer,
or with the target placed slightly oblique to the substrate.
[0058] Preferably, the multilayer film includes an
antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic
electrically conductive layer, and a free magnetic layer, or the
multilayer film includes a free magnetic layer, nonmagnetic
electrically conductive layers respectively lying over and under
the free magnetic layer, pinned magnetic layers respectively lying
over the one nonmagnetic electrically conductive layer and under
the other nonmagnetic electrically conductive layer, and
antiferromagnetic layers respectively lying over the one pinned
magnetic layer and under the other pinned magnetic layer, or the
multilayer film includes a magnetoresistive-effect layer, a soft
magnetic layer, and a nonmagnetic layer wherein the
magnetoresistive-effect layer and the soft magnetic layer are
laminated with the nonmagnetic layer interposed therebetween.
[0059] Preferably, the multilayer film includes at least one of
each of an antiferromagnetic layer, a pinned magnetic layer, a
nonmagnetic electrically conductive layer, and a free magnetic
layer, or the multilayer film includes a free magnetic layer,
nonmagnetic electrically conductive layers respectively lying over
and under the free magnetic layer, pinned magnetic layers
respectively lying over the one nonmagnetic electrically conductive
layer and under the other nonmagnetic electrically conductive
layer, and antiferromagnetic layers respectively lying over the one
pinned magnetic layer and under the other pinned magnetic layer, or
the multilayer film includes a magnetoresistive-effect layer, a
soft magnetic layer, and a nonmagnetic layer wherein the
magnetoresistive-effect layer and the soft magnetic layer are
laminated with the nonmagnetic layer interposed therebetween.
[0060] The free magnetic layer preferably includes a plurality of
soft magnetic thin films having different magnetic moments and
nonmagnetic material layers, which are alternatively laminated with
one soft magnetic thin film separated from another by one
nonmagnetic material layer, and the free magnetic layer is in a
ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
[0061] When the free magnetic layer is fabricated by laminating the
plurality of soft magnetic thin films having different magnetic
moments and the nonmagnetic material layers with one nonmagnetic
material layer interposed between adjacent soft magnetic thin
films, the magnetic coupling junction between the multilayer film
and the bias layer is preferably fabricated of an interface with
the end face of only one of the plurality of the soft magnetic thin
films forming the free magnetic layer, in the step of depositing
the bias layer.
[0062] The pinned magnetic layer preferably includes a plurality of
soft magnetic thin films having different magnetic moments and
nonmagnetic material layers, which are alternately laminated with
one soft magnetic thin film separated from another by one
nonmagnetic material layer, and the pinned magnetic layer is in a
ferrimagnetic state in which the magnetization directions of
adjacent soft magnetic thin films, separated by the nonmagnetic
material layer, are aligned antiparallel to each other.
[0063] The nonmagnetic material layer is preferably made of a
material selected from the group consisting of Ru, Rh, Ir, Cr, Re,
Cu, and alloys thereof.
[0064] In the step of depositing the bias layers, the position of
at least one of the top edge and the bottom edge of the magnetic
coupling junction between the multilayer film and the bias layer in
the direction of the movement of a medium is preferably set to be
at the same level as the position of at least one of the top
surface and the bottom surface of the free magnetic layer or the
magnetoresistive-effect layer in the direction of the movement of
the medium.
[0065] The antiferromagnetic layer is preferably made of a PtMn
alloy. Alternatively, the antiferromagnetic layer may be made of an
X--Mn alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof, or may be made of
a Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0066] Even if the width dimension of the top surface of the
multilayer film, composed of the antiferromagnetic layer, the
pinned magnetic layer, the nonmagnetic electrically conductive
layer, and the free magnetic layer, is defined as a track width Tw,
the full width of the multilayer film does not necessarily exhibit
the magnetoresistive effect. Only the central portion of the width
of the multilayer film offers an excellent reproduction gain,
exhibiting the magnetoresistive effect in practice. The central
portion of the multilayer film having an excellent reproduction
gain is called a sensitive region, and the remaining portions,
formed on both sides of the sensitive region, and having a poor
reproduction gain, are called insensitive regions. The sensitive
region and the insensitive regions are measured using a micro track
profile method. Referring to FIG. 31, the micro track profile
method is discussed.
[0067] As shown in FIG. 31, the conventional
magnetoresistive-effect device (see FIG. 33), including the
multilayer film exhibiting the magnetoresistive effect, the hard
bias layers on both sides of the multilayer film, and the electrode
layers formed on the hard bias layers, is formed on the substrate.
The electrode layers are formed on only both sides of the
multilayer film.
[0068] The width dimension A of the top surface of the multilayer
film not covered with the electrode layers is measured through an
optical microscope. The width dimension A is defined as a track
width Tw measured through an optical method (hereinafter referred
to as an optical track width dimension O-Tw).
[0069] A signal is recorded onto a micro track on the recording
medium. A magnetoresistive-effect device is set to scan the micro
track in the direction of a track width, and the relationship
between the width dimension A and the reproduction output is
measured. Alternatively, the recording medium having the micro
track may be set to scan the magnetoresistive-effect device in the
direction of the track width to measure the relationship between
the width dimension A of the multilayer film and the reproduction
output. The measurement results are shown in the lower portion of
FIG. 31.
[0070] From the measurement results, the reproduction output rises
high at the center of the multilayer film, and gets lower toward
edges thereof. The central portion of the multilayer film exhibits
an excellent magnetoresistive effect, and contributes to the
reproduction capability, while edge portions of the multilayer film
suffers from a poor magnetoresistive effect, resulting a low
reproduction output with an insufficient reproduction
capability.
[0071] The portion, having a width dimension B on the multilayer
film and generating an output equal to or greater than 50% of a
maximum reproduction output, is defined as the sensitive region,
and the portion, having a width dimension C on the multilayer film
and generating an output smaller than 50% of the maximum
reproduction output, is defined as the insensitive region.
[0072] Since the insensitive region offers no effective
reproduction capability, and merely raises a direct current
resistance (DCR), the electrode layer is set to extend over the
insensitive region in the present invention. In this arrangement,
the junction areas of the multilayer film with the hard bias layers
and the electrode layers, formed on both sides of the multilayer
film, are increased. A sense current from the electrode easily
flows into the multilayer film without passing through the hard
bias layer, the direct current resistance is reduced, and the
reproduction characteristics are thus improved.
[0073] As described above, when electrode layers 210 and 210 are
overlapped onto a multilayer film 209 as shown in FIG. 34, the
electrode layers 210 and 210 are connected to the multilayer film
209, permitting a sense current to effectively flow into the
multilayer 209 from the electrode layer 210.
[0074] In order to cause a sense current to effectively flow into
the multilayer film 209 from the electrode layer 210, the thickness
of the electrode layer 210 must be larger than before, the
thickness h1 of the electrode 210 on and in direct contact with the
multilayer film 209 must be larger, and the direct current
resistance of the electrode layer 210 must be reduced.
[0075] If the thickness h1 of the electrode layer 210 is small
relative to that of the multilayer film 209, the direct current
resistance of the electrode layer 210 rises, more likely causing
the sense current from the electrode layer 210 to shunt to a hard
bias layer 205. As a result, the reproduction output can drop.
[0076] With the electrode layer 210 overlapped onto the multilayer
film 209 and the thickness h1 of the electrode layer 210 increased
relative to the thickness of the multilayer film 209, the shunt of
the sense current to the hard bias layer 205 is controlled, and the
sense current effectively flows from the electrode layer 210 to the
multilayer film 209.
[0077] If the electrode layer 210 having a thickness h1 is
deposited on the top surface of the multilayer film 209, a large
step develops between the top surface of the electrode layer 210
and the top surface of the multilayer film 209. When an upper gap
layer 211, made of an insulator material, covers throughout the
electrode layer 210 and the multilayer film 209, the upper gap
layer 211 suffers a poor step coverage, and a film discontinuity
occurs at the step. As a result, the upper gap layer 211 fails to
provide sufficient insulation.
[0078] It is yet another object of the present invention to provide
a magnetoresistive-effect device which increases reproduction
output by reducing a current loss caused by a sense current flowing
into a hard bias layer, while making dominant a sense current
flowing into a sensitive region occupying the central portion of a
multilayer film, and which permits an upper gap layer to be
deposited with proper insulation assured.
[0079] According to a sixth aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
an antiferromagnetic layer, a pinned magnetic layer, which is
deposited on and in contact with the antiferromagnetic layer, and
the magnetization direction of which is pinned through an exchange
anisotropic magnetic field with the antiferromagnetic layer, and a
free magnetic layer, separated from the pinned magnetic layer by a
nonmagnetic electrically conductive layer, a pair of hard bias
layers, deposited on both sides of the multilayer film, for
orienting the magnetization direction of the free magnetic layer
perpendicular to the magnetization direction of the pinned magnetic
layer, and a pair of electrode layers respectively deposited on the
hard bias layers, wherein an intermediate layer, made of at least
one of a high-resistivity material having a resistance higher than
that of the electrode layer and an insulating material, is
interposed between each of the hard bias layers and each of the
electrode layers, and the electrode layers extend over the
multilayer film.
[0080] The multilayer film is preferably fabricated by successively
laminating the antiferromagnetic layer, the pinned magnetic layer,
the nonmagnetic electrically conductive layer, and the free
magnetic layer in that order from below, the antiferromagnetic
layer laterally extends from the layers laminated thereon, and a
pair of hard bias layer, a pair of intermediate layers, and a pair
of electrode layers are respectively laminated on a pair of
metallic layers respectively deposited on the antiferromagnetic
layers in the laterally extending regions thereof.
[0081] According to a seventh aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
a free magnetic layer, nonmagnetic electrically conductive layers
respectively lying over and under the free magnetic layer, pinned
magnetic layers respectively lying over the one nonmagnetic
electrically conductive layer and under the other nonmagnetic
electrically conductive layer, each having a pinned magnetization
direction, and antiferromagnetic layers respectively lying over the
one pinned magnetic layer and under the other pinned magnetic
layer, and a pair of hard bias layers, deposited on both sides of
the multilayer film, for orienting the magnetization direction of
the free magnetic layer perpendicular to the magnetization
direction of the pinned magnetic layer, and a pair of electrode
layers respectively deposited on the hard bias layers, wherein an
intermediate layer, made of at least one of a high-resistivity
material having a resistance higher than that of the electrode
layer and an insulating material, is interposed between each of the
hard bias layers and each of the electrode layers and the electrode
layers extend over the multilayer film.
[0082] The antiferromagnetic layer is preferably made of a PtMn
alloy. Alternatively the antiferromagnetic layer may be made of an
X--Mn alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof, or may be made of
a Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0083] According to an eighth aspect of the present invention, a
magnetoresistive-effect device includes a multilayer film including
a magnetoresistive-effect layer, a soft magnetic layer, and a
nonmagnetic layer with the magnetoresistive-effect layer and the
soft magnetic layer laminated with the nonmagnetic layer interposed
therebetween, a pair of hard bias layers deposited on both sides of
the multilayer film, and a pair of electrode layers respectively
deposited on the hard bias layers, wherein an intermediate layer,
made of at least one of a high-resistivity material having a
resistance higher than that of the electrode layer and an
insulating material, is interposed between each of the hard bias
layers and each of the electrode layers and the electrode layers
extend over the multilayer film.
[0084] The high-resistivity material, which fabricates the
intermediate layer interposed between the hard bias layer and the
electrode layer, is preferably at least one material selected from
the group consisting of TaSiO.sub.2, TaSi, CrSiO.sub.2, CrSi, WSi,
WSiO.sub.2, TiN, and TaN.
[0085] Alternatively, the high-resistivity material, which
fabricates the intermediate layer interposed between the hard bias
layer and the electrode layer, is preferably at least one material
selected from the group consisting of Al.sub.2O.sub.3, SiO.sub.2,
Ti.sub.2O.sub.3, TiO, WO, AlN, Si.sub.3N.sub.4, B.sub.4C, SiC, and
SiAlON.
[0086] The multilayer film preferably includes a central sensitive
region which provides an excellent reproduction gain, exhibiting a
substantial magnetoresistive effect and insensitive regions which
are formed on both sides of the sensitive region, and provide a
poor reproduction gain, exhibiting no substantial magnetoresistive
effect, wherein the electrode layers deposited on both sides of the
multilayer film extend over the insensitive regions of the
multilayer film.
[0087] The sensitive region of the multilayer film is defined as a
region which results in an output equal to or greater than 50% of a
maximum reproduction output while the insensitive regions of the
multilayer film are defined as regions, formed on both sides of the
sensitive region, which result in an output smaller than 50% of the
maximum reproduction output, when the magnetoresistive-effect
device having the electrode layers on both sides only of the
multilayer film scans a micro track, having a signal recorded
thereon, in the direction of a track width.
[0088] The width dimension of the sensitive region of the
multilayer film is preferably equal to an optical track width
O-Tw.
[0089] It is another object of the present invention to provide a
magnetoresistive-effect device which restricts a sense current from
shunting to a hard bias layer while assuring sufficient insulation
in an upper gap layer. To achieve this object, the present
invention employs an intermediate layer, made of a high-resistivity
material having a resistance higher than that of the electrode
layer or an insulating material, interposed between each of the
hard bias layers and each of the electrode layers, and the
electrode layers extend over the multilayer film.
[0090] The intermediate layer of an insulator material interposed
between the hard bias layer and the electrode layer reduces a sense
current shunting into the hard bias layer (i.e., a current loss).
With the electrode layer extending over the multilayer film, the
electrode layer is connected to the multilayer film on the top
surface thereof, thereby permitting the sense current to directly
flow from the electrode layer to the multilayer film.
[0091] In accordance with the first through third aspects of the
present invention, the electrode layer 210 overlaps the multilayer
film 209, but no intermediate layer is interposed between the
electrode layer 210 and the hard bias layer 205. To allow the sense
current to effectively flow from the electrode layer 210 to the
multilayer film 209, the thickness h1 of the electrode layer 210
relative to the multilayer film 209 must be increased to reduce the
direct current resistance of the electrode layer 210 and to
restrict the sense current from shunting to the hard bias layer
205. In this case, a sharp step develops between the top surface of
the electrode layer 210 and the top surface of the multilayer film
209. When an upper gap layer 211 of an insulator material covers
the electrode layer 210 and the multilayer film 209, the upper gap
layer 211 suffers a poor step coverage, and a film discontinuity
occurs at the step. As a result, the upper gap layer 211 fails to
provide sufficient insulation.
[0092] In accordance with the sixth through eighth aspects of the
present invention, the intermediate layer of an insulator material
is interposed between the hard bias layer and the electrode layer.
The sense current is less likely to shunt from the electrode layer
to the hard bias layer regardless of the thickness of the electrode
layer. In contrast to the magnetoresistive-effect layer in
accordance with the first through third aspects, the sense current
effectively flows from the electrode layer to the multilayer film
even if the thickness of the electrode layer is decreased relative
to the thickness of the multilayer film. The
magnetoresistive-effect device of the sixth through eighth aspects
works with a thin electrode layer, thereby reducing a step height
formed between the top surface of the electrode layer and the top
surface of the multilayer film, improving a step coverage of the
upper gap layer formed over the border area between the electrode
layer and the multilayer film, and thereby providing sufficient
insulation.
[0093] The multilayer films in a GMR (Giant Magnetoresistance)
device and an AMR (Anisotropic Magnetoresistance) device offer a
good gain in only a central portion thereof, rather than providing
the magnetoresistive effect in the entire area thereof. Only the
central portion is a substantially working area for exhibiting the
magnetoresistive effect. The portion of the multilayer film having
the excellent reproduction gain is called a sensitive region, and
portions on both sides of the sensitive region are called
insensitive regions. The ratios of the sensitive region and the
insensitive regions respectively to the entire multilayer film is
measured through the micro track profile method. The micro trap
profile method has already been discussed.
[0094] Considering that the multilayer film is formed of the
sensitive region and the insensitive regions, it is yet another
object of the present invention to provide a
magnetoresistive-effect device which allows the sense current to
predominantly flow into the sensitive region having the substantial
magnetoresistive effect. To achieve this object, the electrode
layer overlapping the multilayer is set to extend over the
insensitive region.
[0095] With the electrode layer extending over the insensitive
region, the sense current is allowed to predominantly flow into the
sensitive region rather than the insensitive regions. The
reproduction output is thus increased.
[0096] However, the electrode layer extends over but must not reach
the sensitive region. As will be discussed later, the electrode
layer reaching the sensitive region leads to noise generation and
reduction in the reproduction output.
BRIEF DESCRIPTION OF THE DRAWINGS
[0097] FIG. 1 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a first
embodiment of the present invention;
[0098] FIG. 2 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a second
embodiment of the present invention;
[0099] FIG. 3 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a third
embodiment of the present invention;
[0100] FIG. 4 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a fourth
embodiment of the present invention;
[0101] FIG. 5 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a fifth
embodiment of the present invention;
[0102] FIG. 6 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a sixth
embodiment of the present invention;
[0103] FIG. 7 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a seventh
embodiment of the present invention;
[0104] FIG. 8 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of an eighth
embodiment of the present invention;
[0105] FIG. 9 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a ninth
embodiment of the present invention;
[0106] FIG. 10 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a tenth
embodiment of the present invention;
[0107] FIG. 11 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of an eleventh
embodiment of the present invention;
[0108] FIG. 12 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twelfth
embodiment of the present invention;
[0109] FIG. 13 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a thirteenth
embodiment of the present invention;
[0110] FIG. 14 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a fourteenth
embodiment of the present invention;
[0111] FIG. 15 is a conceptual diagram showing a manufacturing step
of the magnetoresistive-effect device of the present invention;
[0112] FIG. 16 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 15;
[0113] FIG. 17 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 16;
[0114] FIG. 18 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 17;
[0115] FIG. 19 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 18;
[0116] FIG. 20 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a fifteenth
embodiment of the present invention;
[0117] FIG. 21 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a sixteenth
embodiment of the present invention;
[0118] FIG. 22 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a seventeenth
embodiment of the present invention;
[0119] FIG. 23 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of an eighteenth
embodiment of the present invention;
[0120] FIG. 24 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a nineteenth
embodiment of the present invention;
[0121] FIG. 25 is a conceptual diagram showing a manufacturing step
of the magnetoresistive-effect device of the present invention;
[0122] FIG. 26 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 25;
[0123] FIG. 27 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 26;
[0124] FIG. 28 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 27;
[0125] FIG. 29 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 28;
[0126] FIG. 30 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 29;
[0127] FIG. 31 is a diagram showing a measurement method for
measuring a sensitive region and insensitive regions of a
multilayer film of the magnetoresistive-effect device;
[0128] FIG. 32 is a graph showing the relationship of the width
dimension of an electrode layer formed on a multilayer film, a
direct current resistance thereof, and noise generation rate;
[0129] FIG. 33 is a partial cross-sectional view showing the
construction of a conventional magnetoresistive-effect device;
[0130] FIG. 34 is a partial cross-sectional view showing a
magnetoresistive-effect device of the present invention;
[0131] FIG. 35 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twentieth
embodiment of the present invention;
[0132] FIG. 36 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twenty-first
embodiment of the present invention;
[0133] FIG. 37 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twenty-second
embodiment of the present invention;
[0134] FIG. 38 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twenty-third
embodiment of the present invention;
[0135] FIG. 39 is a partial cross-sectional view showing the
construction of a magnetoresistive-effect device of a twenty-fourth
embodiment of the present invention;
[0136] FIG. 40 is a conceptual diagram showing a manufacturing step
of the magnetoresistive-effect device of the present invention;
[0137] FIG. 41 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 40;
[0138] FIG. 42 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 41;
[0139] FIG. 43 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 42; and
[0140] FIG. 44 is a conceptual diagram showing a manufacturing step
performed subsequent to the step of FIG. 43;
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0141] FIG. 1 is a cross-sectional view showing the construction of
a magnetoresistive-effect device of a first embodiment of the
present invention, viewed from an ABS (air bearing surface) side
thereof. FIG. 1 shows only the central portion of the device
sectioned in an XZ plane.
[0142] The magnetoresistive-effect device is a spin-valve type
thin-film device, namely, one type of GMR (giant magnetoresistive)
devices making use of the giant magnetoresistive effect. The
spin-valve type thin-film device is mounted on the trailing end of
a floating slider in a hard disk device to detect a magnetic field
recorded onto a hard disk. The direction of the movement of a
magnetic recording medium such as a hard disk is aligned with the Z
direction, and the direction of a leakage magnetic field of the
magnetic recording medium is aligned with the Y direction.
[0143] A substrate 10, fabricated of a nonmagnetic material such as
Ta (tantalum), becomes the bottom layer of the device as shown in
FIG. 1. An antiferromagnetic layer 11, a pinned magnetic layer 12,
a nonmagnetic electrically conductive layer 13, and a free magnetic
layer 14 are successively laminated onto the substrate 10. A
protective layer 15, fabricated of Ta (tantalum), is deposited on
the free magnetic layer 14. A multilayer film 16 is thus fabricated
of the substrate 10 through the protective layer 15. Referring to
FIG. 1, the width dimension of the top surface of the multilayer
film 16 is defined as T30.
[0144] The pinned magnetic layer 12 is deposited to be in direct
contact with the antiferromagnetic layer 11, and is subjected to
annealing in the presence of a magnetic field. An exchange
anisotropic magnetic field takes place through exchange coupling at
the interface between the antiferromagnetic layer 11 and the pinned
magnetic layer 12. The magnetization of the pinned magnetic layer
12 is thus pinned in the Y direction.
[0145] In accordance with the present invention, the
antiferromagnetic layer 11 is made of a Pt--Mn (platinum-manganese)
alloy. The Pt--Mn alloy film outperforms an Fe--Mn alloy film and
Ni--Mn alloy film, conventionally used as an antiferromagnetic
layer, in terms of corrosion resistance, and has a high blocking
temperature, and further provides a large exchange anisotropic
magnetic field (Hex). The Pt--Mn alloy film has thus excellent
characteristics as an antiferromagnetic material.
[0146] Instead of the Pt--Mn alloy film, the antiferromagnetic
layer 11 may be made of an X--Mn alloy where X' is a material
selected from the group consisting of Pd, Ir, Rh, Ru, and alloys
thereof, or a Pt--Mn--X' alloy where X' is a material selected from
the group consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys
thereof.
[0147] The pinned magnetic layer 12 and the free magnetic layer 14
are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt), an Fe--Co
(iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the nonmagnetic
electrically conductive layer 13 is made of a low
electrical-resistance nonmagnetic electrically conductive material,
such as Cu (copper).
[0148] Referring to FIG. 1, hard bias layers 17 and 17 are
deposited on both sides of the multilayer film 16, composed of the
substrate 10 through the protective layer 15. The hard bias layers
17 and 17 are made of a Co--Pt (cobalt-platinum) alloy or a
Co--Cr--Pt (cobalt-chromium-platinum) alloy.
[0149] The hard bias layers 17 and 17 are magnetized in the X
direction (i.e., the direction of a track width), and the
magnetization of the free magnetic layer 14 is aligned in the X
direction under the bias magnetic field in the X direction by the
hard bias layers 17 and 17.
[0150] The portion having a width dimension T2 in the center of the
multilayer film 16 as shown in FIG. 1 is a sensitive region E, and
the portions, each having a width dimension T1, on both sides of
the sensitive region E, are insensitive regions D and D.
[0151] In the sensitive region E, the magnetization of the pinned
magnetic layer 12 is pinned in the Y direction as shown. Since the
magnetization of the free magnetic layer 14 is aligned in the X
direction, the magnetization of the pinned magnetic layer 12 is
perpendicular to the magnetization of the free magnetic layer 14.
The magnetization of the free magnetic layer 14 varies sensitively
in response to an external magnetic field from the recording
medium. An electrical resistance varies in accordance with the
relationship between the variation in the magnetization direction
of the free magnetic layer 14 and the pinned magnetic field of the
pinned magnetic layer 12. A leakage magnetic field from the
recording medium is thus detected in response to a variation in
voltage due to the electrical resistance variation.
[0152] The sensitive region E of the multilayer film 16 is where
the magnetoresistive effect is substantially exhibited, and the
reproduction function is excellently performed here.
[0153] In contrast, in the insensitive regions D and D formed on
both sides of the sensitive region E, the magnetizations of pinned
magnetic layer 12 and the free magnetic layer 14 are greatly
affected by the hard bias layers 17 and 17, and the magnetization
of the free magnetic layer 14 is less varying in response to the
external magnetic field. In other words, the insensitive regions D
and D provide a weak magnetoresistive effect with a reproduction
capability thereof reduced.
[0154] In this invention, the width dimension T2 of the sensitive
region E, and the width dimension of the insensitive region D of
the multilayer film 16 are measured through the previously
discussed micro track profile method (see FIG. 31).
[0155] Referring to FIG. 1 in this invention, the electrode layers
18 and 18, directly deposited on the hard bias layers 17 and 17 on
both sides of the multilayer film 16, are formed to extend over the
insensitive region D of the multilayer film 16 by a width dimension
of T3. The electrode layers 18 and 18 are made of Cr, Au, Ta, or W
film, for instance. The width dimension of the top surface of the
multilayer film 16 not covered with the electrode layers 18 and 18
is defined as an optical read track width O-Tw measured through an
optical method.
[0156] The width dimension of the sensitive region E not covered
with the electrode layers 18 and 18 substantially functions as a
track width, and this width dimension is defined as a magnetic read
track width M-Tw.
[0157] In the first embodiment shown in FIG. 1, the optical read
track width O-Tw, the magnetic read track width M-Tw, and the width
dimension T2 of the sensitive region E substantially have the same
dimension.
[0158] The sense current is less likely to flow from the electrode
layers 18 and 18 to the hard bias layers 17 and 17 in the present
invention. The percentage of the sense current directly flowing
into the multilayer film 16 without passing through the hard bias
layers 17 and 17 is thus increased. With the electrode layers 18
and 18 respectively extending over the insensitive regions D and D,
the junction area of the multilayer film 16 with the hard bias
layers 17 and 17 and the electrode layers 18 and 18 increases,
reducing the direct current resistance (DCR) and thereby improving
the reproduction characteristics.
[0159] When the electrode layers 18 and 18 are formed to extend
over the insensitive regions D and D, the sense current flowing
into the insensitive regions is controlled and the noise generation
is also controlled.
[0160] When the optical read track width O-Tw and the width
dimension T2 (i.e., the magnetic read track width M-Tw) of the
sensitive region E are set to be approximately the same dimension,
the sense current more easily flows into the sensitive region E,
thereby further improving the reproduction characteristics.
[0161] Although the electrode layers 18 and 18 fully cover the
insensitive regions D and D in this invention, it is not a
requirement that the electrode layers 18 and 18 fully cover the
insensitive regions D and D. The insensitive regions D and D may be
partly exposed. In this case, the optical read track width O-Tw
becomes larger than the magnetic read track width M-Tw.
Specifically, the width dimension T3 of each electrode layer 18
extending over the multilayer film 16 is preferably within a range
from 0 to 0.08 .mu.m. The width dimension T3 is more preferably
within a range from 0.05 .mu.m to 0.08 .mu.m.
[0162] Experimentally, it is found that the electrode layer 18
having a width T3 of 0.08 .mu.m or larger generates a noise signal
in the reproduction output. A width dimension of 0.08 .mu.m is a
maximum value on the top surface of the insensitive region D. If
the electrode layer 18 having a width T3 of 0.08 .mu.m or larger is
formed, the electrode layer 18 partly covers the sensitive region
E.
[0163] The electrode layers 18 and 18 extend over the multilayer
film 16 but must not extend over the sensitive region E.
[0164] The sense current flows out, chiefly from the end of the
electrode layer 18 extending over the multilayer film 16. When the
electrode layers 18 and 18 are formed on the sensitive region E
that substantially exhibits the magnetoresistive effect, the area
of the sensitive region E covered with the electrode layer 18
permits the sense current to less flow. The sensitive region E that
presents an otherwise excellent magnetoresistive effect is partly
degraded, thereby causing a drop in the reproduction output. Since
the area of the sensitive region E covered with the electrode layer
18 still has some sensitivity, a variation in the magnetoresistance
occurs in both ends of the magnetic read track width M-Tw,
inconveniently generating noise.
[0165] According to the results of a micro magnetic simulation,
when the width dimension T3 of the electrode layer 18 is set to be
0.05 .mu.m or wider, the electrode layers 18 and 18 cover the areas
of the free magnetic layer 14 where a magnetization direction
thereof is disturbed, and improves the reproduction characteristics
of the magnetoresistive-effect device.
[0166] The angle .theta.1 made between the top surface 15a of the
protective layer 15 and an end face 18a of the electrode layer 18
extending over the insensitive region of the multilayer film 16 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0167] If the angle .theta.1 made between the top surface 15a and
the end face 18a is too large, a short is likely to occur between
the electrode layer 18 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 18 and 18. The angle .theta.1
made between the top surface 15a and the end face 18a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0168] A spin-valve type thin-film device shown in FIG. 2 also
includes a multilayer film 20 composed of a substrate 10, an
antiferromagnetic layer 11, a pinned magnetic layer 12, a
nonmagnetic electrically conductive layer 13, a free magnetic layer
14, and a protective layer 15, hard bias layers 17 and 17 deposited
on both sides of the multilayer film 20, and electrode layers 18
and 18 respectively deposited on the hard bias layers 17 and 17.
Each electrode layer 18 is formed to extend over the multilayer
film 20 by a width dimension of T5. The electrode layers 18 and 18
extending over the multilayer film 20 fully cover the insensitive
regions D and D. In this case, an optical read track width O-Tw
determined by the width dimension of the top surface of the
multilayer film 20 is approximately equal to the magnetic read
track width dimension M-Tw (i.e., the width dimension of the
sensitive region E) determined by the width dimension of the
sensitive region E not covered by the electrode layers 18 and
18.
[0169] It is not a requirement that the electrode layer 18 fully
cover the insensitive region D. The width dimension T5 of the
electrode layer 18 extending over the multilayer film 20 may be
smaller than the insensitive region D. In this case, the optical
read track width O-Tw is larger than the magnetic read track width
M-Tw. The width dimension T5 of the electrode layer 18 is
preferably within a range from 0 m to 0.08 .mu.m, and more
preferably within a range from 0.05 .mu.m to 0.08 .mu.m. Within
these ranges, the direct current resistance is successfully reduced
while the reproduction output is free from noise.
[0170] In the second embodiment shown in FIG. 2, the width
dimension of the top surface of the multilayer film 20 is T31,
which is larger than the width dimension T30 of the multilayer film
16 shown in FIG. 1. The multilayer film 20 provides a wider
sensitive region E capable of substantially exhibiting the
magnetoresistive effect than the multilayer film 16 shown in FIG.
1. The width dimension of the sensitive region E shown in FIG. 2 is
approximately equal to the width dimension T30 on the top surface
of the multilayer film 16 shown in FIG. 1.
[0171] By enlarging the width dimension of the multilayer film 20,
the influence by the hard bias layers 17 and 17 is reduced, and the
width dimension of the sensitive region E capable of substantially
exhibiting the magnetoresistive effect is set to be larger than
that of the multilayer film 16 shown in FIG. 1. This is because the
width dimension of each of the insensitive regions D and D falls
within a certain range regardless of the width dimension T31 of the
top surface of the multilayer film 20. For this reason, by setting
the width dimension of the multilayer film 20 to any arbitrary
dimension, the width dimension of the sensitive region E, i.e., the
magnetic read track width M-Tw is also set to be any arbitrary
dimension.
[0172] More specifically, even if the top surface of the multilayer
film 16 is sized to be T30, the portion capable of substantially
exhibiting the magnetoresistive effect is limited to the sensitive
region D having the width dimension T2 as shown in FIG. 1. The
second embodiment shown in FIG. 2 is chiefly intended to enlarge
the width dimension of the sensitive region E to be larger than the
width dimension T2 of the sensitive region E shown in FIG. 1. The
width dimension of the top surface of the multilayer film 20 is
enlarged to T31 to this end.
[0173] The angle .theta.2 made between the top surface 15a of the
protective layer 15 and an end face 18a of the electrode layer 18
extending over the insensitive region of the multilayer film 20 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0174] If the angle .theta.2 made between the top surface 15a and
the end face 18a is too large, a short is likely to occur between
the electrode layer 18 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 18 and 18. The angle .theta.2
made between the top surface 15a and the end face 18a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0175] A multilayer film 21 in a spin-valve type thin-film device
of a third embodiment of the present invention shown in FIG. 3 has
an inverted order of the lamination of the multilayer film 20 of
the spin-valve type thin-film device shown in FIG. 2. Specifically,
a free magnetic layer 14, a nonmagnetic electrically conductive
layer 13, a pinned magnetic layer 12, and an antiferromagnetic
layer 11 are successively laminated from the substrate 10 as shown
in FIG. 3.
[0176] In the third embodiment, the free magnetic layer 14 of the
multilayer film 21 shown in FIG. 3 is formed beneath the
antiferromagnetic layer 11, and is in contact with the thick
portion of the hard bias layers 17 and 17. The magnetization of the
free magnetic layer 14 is thus easily aligned in the X direction.
The generation of Barkhausen noise is thus controlled.
[0177] Referring to FIG. 3, the height position of the upper edge
of the magnetic coupling junction M between the multilayer film 21
and the hard bias layers 17 and 17 in the direction of the advance
of the recording medium (i.e., the Z direction in FIG. 3) is at the
same level as the height position of the top surface of the free
magnetic layer 14 in the direction of the advance of the recording
medium.
[0178] It is sufficient if the hard bias layers 17 and 17 are
magnetically coupled with the free magnetic layer 14 only. Since
the hard bias layers 17 and 17 are magnetically uncoupled with the
pinned magnetic layer 12 as shown in FIG. 3, the influence of the
magnetic field created by the hard bias layers 17 and 17 on the
magnetization direction of the pinned magnetic layer 12 is
controlled.
[0179] In the third embodiment again, the width dimension of the
top surface of the multilayer film 21 is enlarged to be larger than
the width dimension T30 of the top surface of the multilayer film
16 shown in FIG. 1. The width dimension of the sensitive region E
of the multilayer film 21 is thus larger than the width dimension
T2 of the sensitive region E shown in FIG. 1.
[0180] Also referring to FIG. 3, the electrode layers 18 and 18 are
formed to extend over the multilayer film 21 on both sides thereof
by a width dimension T7, covering the insensitive regions D and D
of the multilayer film 21. The width dimension T7 of each of the
electrode layers 18 and 18 preferably falls within a range from 0
.mu.m to 0.08 .mu.m. More preferably, the width dimension T7 falls
within a range from 0.05 .mu.m to 0.08 .mu.m.
[0181] In the third embodiment, the electrode layers 18 and 18
deposited above the multilayer film 21 partly cover the insensitive
regions D and D, rather than fully covering them. Specifically, as
shown in FIG. 3, the optical read track width dimension O-Tw,
determined by the width dimension of the top surface of the
multilayer film 21 not covered with the electrode layers 18 and 18,
is set to be larger than the magnetic read track width M-Tw
determined by the width dimension of the sensitive region E not
covered with the electrode layers 18 and 18. In this embodiment
again, the electrode layers 18 and 18 may fully cover the
insensitive regions D and D on the multilayer film 21, thereby
setting the optical read track width O-Tw and the magnetic read
track width M-Tw (i.e., the width dimension of the sensitive region
E) to approximately the same dimension.
[0182] The angle .theta.3 made between the top surface 15a of the
protective layer 15 and an end face 18a of the electrode layer 18
extending over the insensitive region of the multilayer film 21 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0183] If the angle .theta.3 made between the top surface 15a and
the end face 18a is too large, a short is likely to occur between
the electrode layer 18 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 18 and 18. The angle .theta.3
made between the top surface 15a and the end face 18a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0184] FIG. 4 is a cross-sectional view showing the construction of
the magnetoresistive-effect device of a fourth embodiment of the
present invention, viewed from an ABS side thereof.
[0185] A spin-valve type thin-film device shown in FIG. 4 has an
antiferromagnetic layer 30 formed and extending on and along the
substrate 10 in the X direction. The antiferromagnetic layer 30 is
projected upward by a height dimension dl on the center of the
device along the X direction. A pinned magnetic layer 31, a
nonmagnetic electrically conductive layer 32, a free magnetic layer
33, and a protective layer 15 are successively laminated on the
projected antiferromagnetic layer 30. The laminate, composed of the
layers from the substrate 10 through the protective layer 15, forms
a multilayer film 35.
[0186] In the present invention, the antiferromagnetic layer 30 is
made of a Pt--Mn (platinum-manganese) alloy. Instead of the Pt--Mn
alloy film, the antiferromagnetic layer 30 may be made of an X--Mn
alloy where X' is a material selected from the group consisting of
Pd, Ir, Rh, Ru, and alloys thereof, or a Pt--Mn--X' alloy where X'
is a material selected from the group consisting of Pd, Ir, Rh, Ru,
Au, Ag, and alloys thereof.
[0187] The pinned magnetic layer 31 and the free magnetic layer 33
are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt), an Fe--Co
(iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the nonmagnetic
electrically conductive layer 32 is made of a low
electrical-resistance nonmagnetic electrically conductive material,
such as Cu (copper).
[0188] Referring to FIG. 4, metallic layers 36 and 36, made of Cr
or the like, and functioning as a buffer layer or a alignment
layer, extend from a horizontal portion thereof coextending a width
dimension T8 of the antiferromagnetic layer 30 in the X direction,
rising along the side end faces of the pinned magnetic layer 31,
the nonmagnetic electrically conductive layer 32, and the free
magnetic layer 33. The use of the metallic layer 36 helps increase
the strength of the bias magnetic field created by hard bias layers
37 and 37.
[0189] Deposited on top of the metallic layers 36 and 36 are the
hard bias layers 37 and 37 which are made of a Co--Pt
(cobalt-platinum) alloy or a Co--Cr--Pt (cobalt-chromium-platinum)
alloy.
[0190] The hard bias layers 37 and 37 are magnetized in the X
direction (i.e., the direction of the track width) as shown, and
the magnetization direction of the free magnetic layer 33 is thus
aligned in the X direction under the bias field in the X direction
caused by the hard bias layers 37 and 37.
[0191] Since the antiferromagnetic layer 30 extends beneath and
along the hard bias layers 37 and 37 as shown in FIG. 4, the
thickness of the hard bias layers 37 and 37 can be made thinner.
The hard bias layers 37 and 37 are thus easily produced using a
sputtering technique.
[0192] Intermediate layers 38 and 38, made of a nonmagnetic
material, such as Ta, are respectively deposited on the hard bias
layers 37 and 37. Electrode layers 39 and 39, made of Cr, Au, Ta,
or W, are respectively deposited on top of the intermediate layers
38 and 38.
[0193] In the fourth embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 35 are
measured using the micro track profile method. Referring to FIG. 4,
the portion of the multilayer film 35 having a width dimension T9
represents the sensitive region E, and the portion having a width
dimension T10 represents each of the insensitive regions D and
D.
[0194] In the sensitive region E, the magnetization direction of
the pinned magnetic layer 31 is pinned correctly parallel to the Y
direction, and the magnetization direction of the free magnetic
layer 33 is correctly aligned in the X direction. The pinned
magnetic layer 31 and the free magnetic layer 33 are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer 33 varies sensitively in response to an
external magnetic field from the recording medium. An electrical
resistance varies in accordance with the relationship between the
variation in the magnetization direction of the free magnetic layer
33 and the pinned magnetic field of the pinned magnetic layer 31. A
leakage magnetic field from the recording medium is thus detected
in response to a variation in voltage due to the electrical
resistance variation.
[0195] The electrode layers 39 and 39 deposited both sides of the
multilayer film 35 are formed to extend over the multilayer film
35, and the width dimension of the top surface of the multilayer
film 35 having no electrode layers 39 formed thereon is the optical
read width dimension O-Tw.
[0196] The magnetic read track width M-Tw determined by the width
dimension of the sensitive region E not covered with the electrode
layers 39 and 39 is equal to the width dimension T9, which is also
equal to the size of the sensitive region E.
[0197] Since the electrode layer 39 formed on the multilayer film
35 is narrower than the width of the insensitive region D, and does
not fully cover the insensitive region D in this embodiment, the
optical read track width O-Tw is larger than the magnetic read
track width M-Tw. The electrode layers 39 and 39 formed on the
multilayer film 35 may fully cover the insensitive regions D and D,
setting the optical read track width O-Tw and the magnetic read
track width M-Tw (i.e., the width dimension of the sensitive region
E) to approximately the same dimension.
[0198] The percentage of the sense current flowing from the
electrode layers 39 and 39 to the multilayer film 35 without
passing through the hard bias layers 37 and 37 is increased in this
invention. With the electrode layers 39 and 39 respectively
extending over the insensitive regions D and D, the junction area
of the multilayer film 35 and the hard bias layers 37 and 37 and
the electrode layers 39 and 39 is increased, reducing the direct
current resistance (DCR) and improving the reproduction
characteristics.
[0199] Furthermore, the electrode layers 39 and 39 extending over
the insensitive regions D and D restricts the sense current from
flowing into the insensitive regions D and D, thereby controlling
the generation of noise.
[0200] As shown in FIG. 4, the width dimension T11 of the electrode
layer 39 extending over the insensitive region D of the multilayer
film 35 preferably falls within a range from 0 .mu.m to 0.08 .mu.m.
More preferably, the width dimension T11 falls within a range from
0.05 .mu.m to 0.08 .mu.m.
[0201] The angle .theta.4 made between the top surface 15a of the
protective layer 15 and an end face 39a of the electrode layer 39
extending over the insensitive region of the multilayer film 35 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0202] If the angle .theta.4 made between the top surface 15a and
the end face 39a is too large, a short is likely to occur between
the electrode layer 39 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 39 and 39. The angle .theta.4
made between the top surface 15a and the end face 39a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0203] A spin-valve type thin-film device of a fifth embodiment of
the present invention shown in FIG. 5 has a construction identical
to that of the spin-valve type thin-film device shown in FIG. 4.
However, the width dimension of a multilayer film 40 in the
spin-valve type thin-film device in FIG. 5 is set to be larger in
the X direction than that of the top surface of the multilayer film
35 in the spin-valve type thin-film device shown in FIG. 4.
[0204] The width dimension of the sensitive region E of the
multilayer film 40 shown in FIG. 5 is thus larger than the width
dimension T9 of the sensitive region E of the multilayer film 35
shown in FIG. 4.
[0205] The electrode layers 39 and 39 deposited on both sides of
the multilayer film 40 extend over the multilayer film 40, and the
width dimension of the top surface of the multilayer film 40 having
no electrode layers 39 and 39 formed thereon is defined as the
optical read track width O-Tw.
[0206] Since the electrode layers 39 and 39 formed on top of the
multilayer film 40 substantially cover the insensitive regions D
and D as shown FIG. 5, the optical read track width O-Tw becomes
approximately equal to the magnetic read track width M-Tw (i.e.,
the width dimension of the sensitive region E) determined by the
width dimension of the sensitive region E not covered with the
electrode layers 39 and 39. It is not a requirement that the
electrode layers 39 and 39 fully cover the insensitive regions D
and D. If the electrode layers 39 and 39 do not fully cover the
insensitive regions D and D, the optical read track width O-Tw
becomes larger than the magnetic read track width M-Tw. The width
dimension T13 of each of the electrode layers 39 and 39 extending
over the insensitive regions D and D of the multilayer film 40
preferably falls within a range from 0 .mu.m to 0.08 .mu.m. More
preferably, the width dimension T13 falls within a range from 0.05
.mu.m to 0.08 .mu.m.
[0207] The angle .theta.5 made between the top surface 15a of the
protective layer 15 and an end face 39a of the electrode layer 39
extending over the insensitive region of the multilayer film 40 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0208] If the angle .theta.5 made between the top surface 15a and
the end face 39a is too large, a short is likely to occur between
the electrode layer 39 and a top shield layer of a soft magnetic
material when the top shield layer is laminated over the protective
layer 15 and the electrode layers 39 and 39. The angle .theta.5
made between the top surface 15a and the end face 39a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0209] FIG. 6 is a cross-sectional view showing the construction of
the magnetoresistive-effect device of a sixth embodiment of the
present invention, viewed from an ABS side thereof.
[0210] This spin-valve type thin-film device is a so-called dual
spin-valve type thin-film device, which includes a free magnetic
layer 44, nonmagnetic electrically conductive layers 45 and 43
respectively lying over and under the free magnetic layer 44,
pinned magnetic layers 46 and 42 respectively lying over and under
the nonmagnetic electrically conductive layers 45 and 43, and
antiferromagnetic layers 47 and 41 respectively lying over and
under the pinned magnetic layers 46 and 42. The dual spin-valve
type thin-film device provides a reproduction output higher in
level than that of the spin-valve type thin-film devices (i.e.,
so-called single spin-valve type thin-film devices) shown in FIG. 1
through FIG. 5. The layer lying at the bottom is the substrate 10,
while the layer lying on the top is a protective layer 15. The
laminate, composed of the layers from the substrate 10 through the
protective layer 15, constitutes a multilayer film 48.
[0211] In the sixth embodiment of the present invention, the
antiferromagnetic layers 41 and 47 are is made of a Pt--Mn
(platinum-manganese) alloy. Instead of the Pt--Mn alloy, the
antiferromagnetic layers 41 and 47 may be made of an X--Mn alloy
where X' is a material selected from the group consisting of Pd,
Ir, Rh, Ru, and alloys thereof, or a Pt--Mn--X' alloy where X' is a
material selected from the group consisting of Pd, Ir, Rh, Ru, Au,
Ag, and alloys thereof.
[0212] The pinned magnetic layers 42 and 46 and the free magnetic
layer 44 are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt), an
Fe--Co (iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the
nonmagnetic electrically conductive layers 43 and 45 are made of a
low electrical-resistance nonmagnetic electrically conductive
material such as Cu (copper).
[0213] The hard bias layers 49 and 49 are deposited on both sides
of the multilayer film 48 as shown in FIG. 6, and the hard bias
layers 49 and 49 are made of a Co--Pt (cobalt-platinum) alloy or a
Co--Cr--Pt (cobalt-chromium-platinum) alloy.
[0214] The hard bias layers 49 and 49 are magnetized in the X
direction (i.e., the direction of the track width) as shown, and
the magnetization direction of the free magnetic layer 44 is thus
aligned in the X direction under the bias field in the X direction
caused by the hard bias layers 49 and 49.
[0215] In the sixth embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 48 are
measured using the micro track profile method. As shown in FIG. 6,
the portion having the width dimension T15 centrally positioned on
the multilayer film 48 is the sensitive region E, and the portions
having the width dimension T14 are the insensitive regions D and
D.
[0216] In the sensitive region E, the magnetization direction of
the pinned magnetic layers 42 and 46 is pinned correctly in the Y
direction, and the magnetization direction of the free magnetic
layer 44 is correctly aligned in the X direction. The pinned
magnetic layers 42 and 46 and the free magnetic layer 44 are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer 44 varies sensitively in response to an
external magnetic field from the recording medium. An electrical
resistance varies in accordance with the relationship between the
variation in the magnetization direction of the free magnetic layer
44 and the pinned magnetic field of the pinned magnetic layers 42
and 46. A leakage magnetic field from the recording medium is thus
detected in response to a variation in voltage due to the
electrical resistance variation.
[0217] Referring to FIG. 6 in this invention, intermediate layers
50 and 50 made of a nonmagnetic material are respectively deposited
on the hard bias layers 49 and 49 on both sides of the multilayer
film 48. Electrode layers 51 and 51 are then respectively deposited
on the intermediate layers 50 and 50 and respectively extend over
the insensitive regions D and D of the multilayer film 48. The
electrode layers 51 and 51 are made of Cr, Au, Ta, or W film, for
instance.
[0218] The width dimension of the top surface of the multilayer
film 48 not covered with the electrode layers 51 and 51 is defined
as an optical read track width O-Tw. The width dimension T15 of the
sensitive region E not covered with the electrode layers 51 and 51
is defined as the magnetic read track width M-Tw. In the sixth
embodiment, the electrode layers 51 and 51 extending over the
multilayer film 48 fully cover the insensitive regions D and D. The
optical read track width O-Tw is approximately equal to the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E).
[0219] It is not a requirement that the electrode layers 51 and 51
fully cover the insensitive regions D and D, and the width
dimension T5 of the electrode layer 51 extending over the
multilayer film 48 is smaller than the insensitive region D. In
this case, the optical read track width O-Tw becomes larger than
the magnetic read track width M-Tw.
[0220] This arrangement makes it easier for the sense current to
directly flow from the electrode layer 51 into the multilayer film
48 without passing through the hard bias layer 49. With the
electrode layers 51 and 51 respectively extending over the
insensitive regions D and D, the junction area between the
multilayer film 48 and the hard bias layer 49 and the electrode
layer 51 is increased, reducing the direct current resistance (DCR)
and thereby improving the reproduction characteristics.
[0221] Furthermore, the electrode layers 51 and 51 respectively
extending over the insensitive regions D and D prevent the sense
current flowing into the insensitive regions D and D, thereby
controlling the generation of noise.
[0222] Referring to FIG. 6, the width dimension T16 of each of the
electrode layers 51 and 51 extending over the insensitive regions D
and D of the multilayer film 48 preferably falls within a range
from 0 .mu.m to 0.08 .mu.m. More preferably, the width dimension
T16 falls within a range from 0.05 .mu.m to 0.08 .mu.m.
[0223] The angle .theta.6 made between the top surface 15a of the
protective layer 15 and an end face 51a of the electrode layer 51
extending over the insensitive region of the multilayer film 48 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0224] If the angle .theta.6 made between the top surface 15a and
the end face 51a is too large, a short is likely to occur between
the electrode layer 51 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 51 and 51. The angle .theta.6
made between the top surface 15a and the end face 51a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0225] A dual spin-valve type thin-film device of a seventh
embodiment of the present invention shown in FIG. 7 has a
construction identical to that of the dual spin-valve type
thin-film device shown in FIG. 6. However, the width dimension of a
multilayer film 60 in the spin-valve type thin-film device in FIG.
7 is set to be larger in the X direction than that of the
multilayer film 48 in the spin-valve type thin-film device shown in
FIG. 6.
[0226] Referring to FIG. 7, the multilayer film 60 is formed to be
longer than the multilayer film 48 shown in FIG. 6, and the width
dimension of the sensitive region E of the multilayer film 60 is
thus larger than the width dimension of the sensitive region E of
the multilayer film 48.
[0227] The electrode layers 51 and 51 formed on both sides of the
multilayer film 60 extend over the multilayer film 60, and the
insensitive regions D and D of the multilayer film 60 are covered
with the electrode layers 51 and 51.
[0228] The width dimension T18 of each of the electrode layers 51
and 51 extending over the insensitive regions D and D of the
multilayer film 60 preferably falls within a range from 0 .mu.m to
0.08 .mu.m. More preferably, the width dimension T18 falls within a
range from 0.05 .mu.m to 0.08 .mu.m. The angle .theta.7 made
between the top surface 15a of the protective layer 15 and an end
face 51a of the electrode layer 51 extending over the insensitive
region of the multilayer film 60 is preferably 20 degrees or
greater, and more preferably 25 degrees or greater. This
arrangement prevents the sense current from shunting into the
insensitive region, thereby controlling the generation of
noise.
[0229] If the angle .theta.7 made between the top surface 15a and
the end face 51a is too large, a short is likely to occur between
the electrode layer 51 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 51 and 51. The angle .theta.7
made between the top surface 15a and the end face 51a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0230] FIG. 8 is a cross-sectional view of the
magnetoresistive-effect device of an eighth embodiment of the
present invention, viewed from an ABS side thereof.
[0231] The magnetoresistive-effect device shown in FIG. 8 is called
an anisotropic magnetoresistive-effect (AMR) device. A soft
magnetic layer (a SAL layer) 52, a nonmagnetic layer (a shunt
layer) 53, a magnetoresistive layer (MR layer) 54, and a protective
layer 55 are successively laminated in that order to form a
multilayer film 61. Hard bias layers 56 and 56 are formed on both
sides of the multilayer film 61. Typically, the soft magnetic layer
52 is made of an NiFeNb alloy, the nonmagnetic layer 53 is made of
Ta, the magnetoresistive layer 54 is made of an NiFe alloy, and the
hard bias layers 56 and 56 are made of a CoPt alloy.
[0232] In the eight embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 61 are
measured using the micro track profile method. The portion having
the width dimension T19 centrally positioned on the multilayer film
61 is the sensitive region E, and the portions, each having the
width dimension T20, are the insensitive regions D and D.
[0233] Intermediate layers 57 and 57, made of a nonmagnetic
material, are respectively deposited on the hard bias layers 56 and
56 on both sides of the multilayer film 61, and electrode layers 58
and 58, made of Cr, Au, Ta, or W, are respectively formed on the
intermediate layers 57 and 57.
[0234] Referring to FIG. 8, the electrode layers 58 and 58 are
formed to extend over the multilayer film 61. The width dimension
of the top surface of the multilayer film 61 having no electrode
layer 58 thereon is the optical read track width O-Tw, and the
width dimension of the sensitive region E not covered with the
electrode layer 58 is the magnetic read track width M-Tw. In the
eighth embodiment, the electrode layers 58 and 58 extending over
the multilayer film 61 fully cover the insensitive regions D and D.
The optical read track width O-Tw is thus approximately equal to
the magnetic read track width M-Tw.
[0235] It is not a requirement that the electrode layers 58 and 58
fully cover the insensitive regions D and D, and the width
dimension T21 of the electrode layer 58 extending over the
multilayer film 61 may be smaller than the insensitive region D. In
this case, the optical read track width O-Tw becomes larger than
the magnetic read track width M-Tw.
[0236] This arrangement makes it easier for the sense current to
directly flow from the electrode layer 51 into the multilayer film
48 without passing through the hard bias layer 49. With the
electrode layers 58 and 58 respectively extending over the
insensitive regions D and D, the junction area between the
multilayer film 61 and the hard bias layer 56 and the electrode
layer 58 is increased, reducing the direct current resistance (DCR)
and thereby improving the reproduction characteristics.
[0237] Furthermore, the electrode layers 58 and 58 respectively
extending over the insensitive regions D and D prevent the sense
current flowing into the insensitive regions D and D, thereby
controlling the generation of noise.
[0238] The width dimension T21 of each of the electrode layers 58
and 58 extending over the insensitive regions D and D of the
multilayer film 61 preferably falls within a range from 0 .mu.m to
0.08 .mu.m. More preferably, the width dimension T21 falls within a
range from 0.05 .mu.m to 0.08 .mu.m.
[0239] In the AMR device, the hard bias layer 56 is magnetized in
the X direction as shown, and the magnetoresistive layer 54 is
supplied with the bias magnetic field in the X direction by the
hard bias layer 56. Furthermore, the magnetoresistive layer 54 is
supplied with the bias field in the Y direction by the soft
magnetic layer 52. With the magnetoresistive layer 54 supplied with
the bias magnetic fields in the X direction and Y direction, a
variation in magnetization thereof in response to a variation in
the magnetic field becomes linear.
[0240] The sense current from the electrode layer 58 is directly
fed to the magnetoresistive layer 54 in the sensitive region E. The
direction of the advance of the recording medium is aligned with
the Z direction. When a leakage magnetic field from the recording
medium in the Y direction is applied, the magnetization direction
of the magnetoresistive layer 54 varies, causing a variation in the
resistance. The resistance variation is then detected as a voltage
variation.
[0241] The angle .theta.8 made between the top surface 55a of the
protective layer 55 and an end face 58a of the electrode layer 58
extending over the insensitive region of the multilayer film 61 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0242] If the angle .theta.8 made between the top surface 55a and
the end face 58a is too large, a short is likely to occur between
the electrode layer 58 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 55 and the electrode layers 58 and 58. The angle .theta.8
made between the top surface 55a and the end face 58a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0243] An AMR device of a ninth embodiment of the present invention
shown in FIG. 9 has a construction identical to that of the AMR
shown in FIG. 8. However, the width dimension of a multilayer film
62 is set to be larger than the width dimension of the multilayer
film 61 in the X direction, as shown in FIG. 8. The sensitive
region E of the multilayer film 62 shown in FIG. 9 is therefore
larger in width dimension than the sensitive region E of the
multilayer film 61 shown in FIG. 8.
[0244] Each of electrode layers 58 and 58 formed on both sides of
the multilayer film 62 extends over the multilayer film 62. The
insensitive regions D and D are thus covered with the electrode
layers 58 and 58.
[0245] The width dimension T23 of each of the electrode layers 58
and 58 extending over the insensitive regions D and D of the
multilayer film 62 preferably falls within a range from 0 .mu.m to
0.08 .mu.m. More preferably, the width dimension T23 falls within a
range from 0.05 .mu.m to 0.08 .mu.m.
[0246] The angle .theta.9 made between the top surface 55a of the
protective layer 55 and an end face 58a of the electrode layer 58
extending over the insensitive region of the multilayer film 62 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater, and preferably 60 degrees or smaller, and more preferably,
45 degrees or smaller.
[0247] FIG. 10 is a cross-sectional view showing the construction
of the magnetoresistive-effect device of a tenth embodiment of the
present invention, viewed from an ABS side thereof.
[0248] The spin-valve type thin-film device shown in FIG. 10
includes an antiferromagnetic layer 70 which has a long portion
extending on and along a substrate 10 in the X direction as shown.
The antiferromagnetic layer 70 is projected upward in a central
portion thereof. Laminated on the projected portion of the
antiferromagnetic layer 70 are a pinned magnetic layer 71, a
nonmagnetic electrically conductive layer 72, a first free magnetic
layer 73, a nonmagnetic material layer 74, a second free magnetic
layer 75, and a protective layer 15. The laminate, composed of the
layers from the substrate 10 through the protective layer 15, forms
a multilayer film 200.
[0249] The pinned magnetic layer 71 is deposited on and in contact
with the antiferromagnetic layer 70, and is subjected to annealing
in the presence of a magnetic field. An exchange anisotropic
magnetic field takes place through exchange coupling at the
interface between the antiferromagnetic layer 70 and the pinned
magnetic layer 71. The magnetization of the pinned magnetic layer
71 is thus pinned in the Y direction.
[0250] In accordance with the present invention, the
antiferromagnetic layer 71 is made of a Pt--Mn (platinum-manganese)
alloy. Instead of the Pt--Mn alloy film, the antiferromagnetic
layer 71 may be made of an X--Mn alloy where X is a material
selected from the group consisting of Pd, Ir, Rh, Ru, and alloys
thereof, or a Pt--Mn--X' alloy where X' is a material selected from
the group consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys
thereof.
[0251] The pinned magnetic layer 71, the first free magnetic layer
73, and the second free magnetic layer 75 are made of an Ni--Fe
(nickel-iron) alloy, Co (cobalt), an Fe--Co (iron-cobalt) alloy, or
an Fe--Co--Ni alloy.
[0252] The nonmagnetic electrically conductive layer 72 is made of
a low electrical-resistance nonmagnetic electrically conductive
material such as Cu (copper).
[0253] Referring to FIG. 10, metallic layers 76 and 76, made of Cr
or the like, and functioning as a buffer layer or a alignment
layer, extend from a horizontal portion thereof coextending a width
dimension T40 of the antiferromagnetic layer 70 in the X direction,
rising along the side end faces of the pinned magnetic layer 71,
the nonmagnetic electrically conductive layer 72, the first free
magnetic layer 73, the nonmagnetic material layer 74, and the
second free magnetic layer 75. The use of the metallic layers 76
and 76 helps increase the strength of the bias magnetic field
created by hard bias layers 77 and 77 to be described later.
[0254] Deposited on top of the metallic layers 76 and 76 are the
hard bias layers 77 and 77 which are made of a Co--Pt
(cobalt-platinum) alloy or a Co--Cr--Pt (cobalt-chromium-platinum)
alloy.
[0255] Intermediate layers 78 and 78, made of a nonmagnetic
material such as Ta, are respectively deposited on the hard bias
layers 77 and 77. Electrode layers 79 and 79, made of Cr, Au, Ta,
or W, are respectively deposited on top of the intermediate layers
78 and 78.
[0256] Since the antiferromagnetic layer 70 extends beneath and
along the hard bias layers 77 and 77 as shown in FIG. 10, the
thickness of the hard bias layers 77 and 77 can be made thinner.
The hard bias layers 77 and 77 are thus easily produced using a
sputtering technique.
[0257] The first free magnetic layer 73 and the second free
magnetic layer 75 are formed to have different magnetic moments.
The magnetic moment is expressed by the product of the saturation
magnetization (Ms) and the thickness (t) of the layer. For example,
the first free magnetic layer 73 and the second free magnetic layer
75 are manufactured of the same material with thicknesses thereof
made different so that the two layers have different magnetic
moments.
[0258] The nonmagnetic material layer 74, interposed between the
first free magnetic layer 73 and the second free magnetic layer 75,
is preferably made of a material selected from the group consisting
of Ru, Rh, Ir, Cr, Re, Cu, and alloys thereof.
[0259] Referring to FIG. 10, the first free magnetic layer 73, and
the second free magnetic layer 75, having different magnetic
moments, are laminated with the nonmagnetic material layer 74
interposed therebetween, and function as a single free magnetic
layer F.
[0260] The first free magnetic layer 73 and the second free
magnetic layer 75 are in a ferrimagnetic state with magnetization
directions thereof being antiparallel, namely different from each
other by 180 degrees. The magnetization direction of the first free
magnetic layer 73 or the second free magnetic layer 75, whichever
has a greater magnetic moment, is aligned with the direction of the
magnetic field generated by the hard bias layers 77 and 77.
Assuming that the first free magnetic layer 73 has a greater
magnetic moment, the magnetization direction of the first free
magnetic layer 73 is aligned with the direction of the magnetic
field generated by the hard bias layers 77 and 77 while the
magnetization direction of the second free magnetic layer 75 is 180
degrees opposite.
[0261] The first free magnetic layer 73 and the second free
magnetic layer 75, which are in a ferrimagnetic state with
magnetization directions thereof being antiparallel, namely
different from each other by 180 degrees, achieve the same effect,
which can be provided by the use of a thin free magnetic layer F.
This arrangement reduces the saturation magnetization, causing the
magnetization of the free magnetic layer F to easily vary, and
thereby improving the magnetic field detection sensitivity of the
magnetoresistive-effect device.
[0262] The direction of the sum of the magnetic moments of the
first free magnetic layer 73 and the second free magnetic layer 75
becomes the magnetization direction of the free magnetic layer
F.
[0263] Because of the relationship with the magnetization direction
of the pinned magnetic layer 71, only the magnetization direction
of the first free magnetic layer 73 contributes to the reproduction
output.
[0264] The hard bias layers 77 and 77 are magnetized in the X
direction (i.e., the direction of the track width), and the
magnetization of the free magnetic layer F is aligned with the X
direction under the bias magnetic field in the X direction given by
the hard bias layers 77 and 77.
[0265] The second free magnetic layer 75 having a magnetization
direction thereof 180 degrees opposite from the direction of the
magnetic field generated by the hard bias layers 77 and 77, is
subject to disturbance in magnetization direction in the vicinity
of two end portions thereof magnetically coupled with the hard bias
layers 77 and 77. In response to this disturbance, the first free
magnetic layer 73 suffers from magnetization direction disturbance
on its end portions together therewith.
[0266] The two end portions of the free magnetic layer F having
disturbed magnetization directions have a poor reproduction gain,
and become insensitive regions unable to exhibit no substantial
magnetoresistive effect.
[0267] In the tenth embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 200 are
measured using the micro track profile method. Referring to FIG.
10, the portion having the width dimension T41 of the multilayer
film 200 is the sensitive region E, and the portions having the
width dimension T42 are the insensitive regions D and D.
[0268] In the sensitive region E, the magnetization direction of
the pinned magnetic layer 71 is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer 71 and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer 71. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation. However, those which directly contribute to the
variation in the electrical resistance (i.e., the reproduction
output) are a relative angle made between the magnetization
direction of the pinned magnetic layer 71 and the magnetization
direction of the first free magnetic layer 73. These magnetization
directions are preferably perpendicular with a sense current
conducted in the absence of a signal magnetic field.
[0269] Electrode layers 79 and 79, deposited on both sides of the
multilayer film 200, extend over the multilayer film 200. The width
dimension of the top layer of the multilayer film 200 not covered
with the electrode layers 79 and 79 is the optical read track width
O-Tw.
[0270] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 79 and 79, is a width dimension T41, which is also the
dimension of the sensitive region E.
[0271] In the tenth embodiment, the electrode layers 79 and 79
formed above the multilayer film 200 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0272] It is not a requirement that the electrode layers 79 and 79
formed above the multilayer film 200 fully cover the insensitive
regions D and D, and the electrode layer 79 may be narrower than
the insensitive region D. In this case, the optical read track
width O-Tw becomes larger than the magnetic read track width
M-Tw.
[0273] The percentage of the sense current flowing from the
electrode 79 to the multilayer film 200 without passing through the
hard bias layers 77 and 77 is increased in this invention.
[0274] The electrode layers 79 and 79 extending over the
insensitive regions D and D prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0275] Referring to FIG. 10, the width dimension T43 of each of the
electrode layers 79 and 79 extending over the insensitive region D
of the multilayer film 200 preferably falls within a range from 0
.mu.m to 0.08 .mu.m. More preferably, the width dimension T43 of
the electrode layer 79 falls within a range from 0.05 .mu.m to 0.08
.mu.m.
[0276] The angle .theta.10 made between the top surface 15a of the
protective layer 15 and an end face 79a of the electrode layer 79
extending over the insensitive region of the multilayer film 200 is
preferably 20 degrees or greater, and more preferably 25 degrees or
greater. This arrangement prevents the sense current from shunting
into the insensitive region, thereby controlling the generation of
noise.
[0277] If the angle .theta.10 made between the top surface 15a and
the end face 79a is too large, a short is likely to occur between
the electrode layer 79 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 15 and the electrode layers 79 and 79. The angle .theta.10
made between the top surface 15a and the end face 79a is preferably
60 degrees or smaller, and more preferably, 45 degrees or
smaller.
[0278] FIG. 11 is a cross-sectional view showing the construction
of the magnetoresistive-effect device of an eleventh embodiment of
the present invention, viewed from an ABS side thereof.
[0279] The spin-valve type thin-film device shown in FIG. 11
includes an antiferromagnetic layer 80 which has a long portion
extending on and along a substrate 10 in the X direction as shown.
The antiferromagnetic layer 80 is projected upward in a central
portion thereof. Laminated on the projected portion of the
antiferromagnetic layer 80 are a first pinned magnetic layer 81, a
nonmagnetic material layer 82, a second pinned magnetic layer 83, a
nonmagnetic electrically conductive layer 84, a first free magnetic
layer 85, a nonmagnetic material layer 86, a second free magnetic
layer 87, and a protective layer 15. The laminate, composed of the
layers from the substrate 10 through the protective layer 15, forms
a multilayer film 201.
[0280] In accordance with the present invention, the
antiferromagnetic layer 80 is made of a Pt--Mn (platinum-manganese)
alloy. Instead of the Pt--Mn alloy, the antiferromagnetic layer 80
may be made of an X--Mn alloy where X is a material selected from
the group consisting of Pd, Ir, Rh, Ru, and alloys thereof, or a
Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0281] The first pinned magnetic layer 81, the second pinned
magnetic layer 83, the first free magnetic layer 85, and second
free magnetic layer 87 are made of an Ni--Fe (nickel-iron) alloy,
Co (cobalt), an Fe--Co (iron-cobalt) alloy, or an Fe--Co--Ni
alloy.
[0282] The nonmagnetic electrically conductive layer 84 is made of
a low electrical-resistance nonmagnetic electrically conductive
material such as Cu (copper).
[0283] Referring to FIG. 11, metallic layers 88 and 88, made of Cr
or the like, and functioning as a buffer layer or a alignment
layer, extend from a horizontal portion thereof coextending a width
dimension T44 of the antiferromagnetic layer 80 in the X direction,
rising along the side end faces of the first pinned magnetic layer
81, the nonmagnetic material layer 82, the second pinned magnetic
layer 83, the nonmagnetic electrically conductive layer 84, and the
first free magnetic layer 85. The use of the metallic layers 88 and
88 helps increase the strength of the bias magnetic field created
by hard bias layers 89 and 89 to be described later.
[0284] Deposited on top of the metallic layers 88 and 88 are the
hard bias layers 89 and 89 which are made of a Co--Pt
(cobalt-platinum) alloy or a Co--Cr--Pt (cobalt-chromium-platinum)
alloy.
[0285] Intermediate layers 90 and 90, made of a nonmagnetic
material, such as Ta, are respectively deposited on the hard bias
layers 89 and 89. Electrode layers 91 and 91, made of Cr, Au, Ta,
or W, are respectively deposited on top of the intermediate layers
90 and 90.
[0286] Since the antiferromagnetic layer 80 extends beneath and
along the hard bias layers 89 and 89 as shown in FIG. 11, the
thickness of the hard bias layers 89 and 89 can be made thinner.
The hard bias layers 89 and 89 are thus easily produced using a
sputtering technique.
[0287] Referring to FIG. 11, the first pinned magnetic layer 81 and
the second pinned magnetic layer 83, having different magnetic
moments, are laminated to each other with the nonmagnetic material
layer 82 interposed therebetween, and function as a single pinned
magnetic layer P.
[0288] The first pinned magnetic layer 81 is deposited on and in
contact with the antiferromagnetic layer 80, and is subjected to
annealing in the presence of a magnetic field. An exchange
anisotropic magnetic field takes place through exchange coupling at
the interface between the first pinned magnetic layer 81 and the
antiferromagnetic layer 80. The magnetization direction of the
first pinned magnetic layer 81 is thus pinned in the Y direction.
When the magnetization direction of the first pinned magnetic layer
81 is pinned in the Y direction, the magnetization direction of the
second pinned magnetic layer 83, separated from the first pinned
magnetic layer 81 by the intervening nonmagnetic material layer 82,
is pinned to be antiparallel to the magnetization direction of the
first pinned magnetic layer 81.
[0289] The direction of the sum of the magnetic moments of the
first pinned magnetic layer 81 and the second pinned magnetic layer
83 becomes the magnetization direction of the pinned magnetic layer
P.
[0290] The first pinned magnetic layer 81 and the second pinned
magnetic layer 83 are in a ferrigmagnetic state with magnetization
directions thereof being antiparallel, and the magnetization
direction of the first pinned magnetic layer 81 and the
magnetization direction of the second pinned magnetic layer 83
mutually pin each other. The magnetization direction of the pinned
magnetic layer P, as a whole, is advantageously stabilized in one
direction.
[0291] Referring to FIG. 11, the first pinned magnetic layer 81 and
the second pinned magnetic layer 83 are manufactured of the same
material with thicknesses thereof made different so that the two
layers have different magnetic moments.
[0292] The nonmagnetic material layer 82, interposed between the
first pinned magnetic layer 81 and the second pinned magnetic layer
83, is preferably made of a material selected from the group
consisting of Ru, Rh, Ir, Cr, Re, Cu, and alloys thereof.
[0293] The first free magnetic layer 85 and the second free
magnetic layer 87 are formed to have different magnetic moments.
Here again, the first free magnetic layer 85 and the second free
magnetic layer 87 are manufactured of the same material with
thicknesses thereof made different so that the two layers have
different magnetic moments.
[0294] The nonmagnetic material layer 86 is preferably made of a
material selected from the group consisting of Ru, Rh, Ir, Cr, Re,
Cu, and alloys thereof.
[0295] Referring to FIG. 11, the first free magnetic layer 85 and
the second free magnetic layer 87, having different magnetic
moments, are laminated with the nonmagnetic material layer 86
interposed therebetween, and function as a single free magnetic
layer F.
[0296] The first free magnetic layer 85 and the second free
magnetic layer 87, which are in a ferrimagnetic state with
magnetization directions thereof being antiparallel, namely
different from each other by 180 degrees, achieve the same effect,
which can be provided by the use of a thin free magnetic layer F.
This arrangement reduces the saturation magnetization, causing the
magnetization of the free magnetic layer F to easily vary, and
thereby improving the magnetic field detection sensitivity of the
magnetoresistive-effect device.
[0297] The direction of the sum of the magnetic moments of the
first free magnetic layer 85 and the second free magnetic layer 87
becomes the magnetization direction of the free magnetic layer F.
However, those which directly contribute to the reproduction output
are a relative angle made between the second pinned magnetic layer
83 and the first free magnetic layer 85.
[0298] The hard bias layers 89 and 89 are magnetized in the X
direction (i.e., the direction of the track width), and the
magnetization direction of the free magnetic layer F is aligned in
the X direction under the bias magnetic field in the X direction
given by the hard bias layers 89 and 89.
[0299] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0300] In the eleventh embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 201 are
measured using the micro track profile method. Referring to FIG.
11, the portion having the width dimension T45 of the multilayer
film 201 is the sensitive region E, and the portions, each having
the width dimension T46, are the insensitive regions D and D.
[0301] In the sensitive region E, the magnetization direction of
the pinned magnetic layer P is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer P and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer P. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation. However, those which directly contribute to the
variation in the electrical resistance (i.e., the reproduction
output) are a relative angle made between the magnetization
direction of the second pinned magnetic layer 83 and the
magnetization direction of the first free magnetic layer 85. These
magnetization directions are preferably perpendicular with a sense
current conducted in the absence of a signal magnetic field.
[0302] Electrode layers 91 and 91, formed on both sides of the
multilayer film 201, extend over the multilayer film 201. The width
dimension of the top layer of the multilayer film 201 not covered
with the electrode layers 91 and 91 is the optical read track width
O-Tw.
[0303] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 91 and 91, is a width dimension T45, which is also the
dimension of the sensitive region E.
[0304] In this embodiment, the electrode layers 91 and 91 formed
above the multilayer film 201 fully cover the insensitive regions D
and D, setting the optical read track width O-Tw and the magnetic
read track width M-Tw (i.e., the width dimension of the sensitive
region E) to approximately the same dimension.
[0305] It is not a requirement that the electrode layers 91 and 91
formed above the multilayer film 201 fully cover the insensitive
regions D and D, and the electrode layer 91 may be narrower than
the insensitive region D. In this case, the optical read track
width O-Tw becomes larger than the magnetic read track width
M-Tw.
[0306] The percentage of the sense current flowing from the
electrode 91 to the multilayer film 201 without passing through the
hard bias layers 89 and 89 is increased.
[0307] The electrode layers 91 and 91 respectively extending over
the insensitive regions D and D prevent the sense current from
flowing into the insensitive regions D and D, thereby controlling
the generation of noise.
[0308] Referring to FIG. 11, the width dimension T47 of each of the
electrode layers 91 and 91 extending over the insensitive region D
of the multilayer film 201 preferably falls within a range from 0
.mu.m to 0.08 .mu.m. More preferably, the width dimension T47 of
each of the electrode layers 91 and 91 falls within a range from
0.05 .mu.m to 0.08 am.
[0309] The angle .theta.11 made between the top surface of the
multilayer film 201 with the protective layer 15 removed, namely,
the top surface 87a of the second free magnetic layer 87 in FIG.
11, and an end face 91a of the electrode layer 91 extending over
the insensitive region of the multilayer film 201 is preferably 20
degrees or greater, and more preferably 25 degrees or greater. This
arrangement prevents the sense current from shunting into the
insensitive region, thereby controlling the generation of
noise.
[0310] If the angle .theta.11 made between the top surface 87a and
the end face 91a is too large, a short is likely to occur between
the electrode layers 91 and 91 and a top shield layer of a soft
magnetic material when the top shield layer is deposited over the
protective layer 15 and the electrode layers 91 and 91. The angle
.theta.11 made between the top surface 87a and the end face 91a is
preferably 60 degrees or smaller, and more preferably, 45 degrees
or smaller.
[0311] Referring to FIG. 11, a magnetic coupling junction M between
the multilayer film 201 and each of the hard bias layers 89 and 89
is fabricated of an interface with the end face of only the first
free magnetic layer 85, of both the first free magnetic layer 85
and the second free magnetic layer 87.
[0312] It is sufficient if the hard bias layers 89 and 89 are
aligned with the magnetization direction of one of the first free
magnetic layer 85 and the second free magnetic layer 87. If the
magnetization direction of one of the free magnetic layers is
aligned in one direction, another free magnetic layer adjacent
thereto is put into a ferrimagnetic state with a magnetization
direction thereof being antiparallel. The direction of the sum of
the magnetic moments of the first and second free magnetic layers
is aligned in a certain direction, namely, the direction of the
track width in FIG. 11.
[0313] If the hard bias layers 89 and 89 are magnetically coupled
with each of the first free magnetic layer 85 and the second free
magnetic layer 87, the first free magnetic layer 85 and the second
free magnetic layer 87 suffer from a larger magnetization direction
disturbance on end portions thereof. However, the construction
shown in FIG. 11 controls the magnetization direction disturbance
on both end portions of each of the free magnetic layers,
permitting the width dimension T45 of the sensitive region E to be
enlarged.
[0314] As shown in FIG. 11, the protective layer 15 is deposited
where the multilayer film 201 has no electrode layers 91 and 91
formed thereon. The electrode layers 91 and 91 are connected to the
second free magnetic layer 87 with no protective layer 15
interposed therebetween.
[0315] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 91 and 91 are
deposited on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0316] A multilayer film 202 of a spin-valve type thin-film device
of a twelfth embodiment of the present invention shown in FIG. 12
has the inverted version of the multilayer film 201 of the
spin-valve type thin-film device shown in FIG. 11. Specifically,
referring to FIG. 12, a second free magnetic layer 87, a
nonmagnetic material layer 86, a first free magnetic layer 85, a
nonmagnetic electrically conductive layer 84, a second pinned
magnetic layer 83, a nonmagnetic material layer 82, a first pinned
magnetic layer 81, an antiferromagnetic layer 80, and a protective
layer 15 are successively laminated on a substrate 10.
[0317] Referring to FIG. 12, the hard bias layers 89 and 89 are
magnetically coupled with neither of the first pinned magnetic
layer 81 and the second pinned magnetic layer 83. This arrangement
prevents the magnetization directions of the first pinned magnetic
layer 81 and the second pinned magnetic layer 83 aligned in a
direction parallel to the Y direction, from varying under the
magnetic field applied by the hard bias layers 89 and 89. The
characteristics of the magnetoresistive-effect device are thus
improved.
[0318] Referring to FIG. 12, the first pinned magnetic layer 81 and
the second pinned magnetic layer 83, having different magnetic
moments, are laminated to each other with the nonmagnetic material
layer 82 interposed therebetween, and function as a single pinned
magnetic layer P. Referring to FIG. 12, the first pinned magnetic
layer 81 and the second pinned magnetic layer 83 are manufactured
of the same material with thicknesses thereof made different so
that the two layers have different magnetic moments.
[0319] As shown in FIG. 12, the first pinned magnetic layer 81 is
deposited on and in contact with the antiferromagnetic layer 80,
and is subjected to annealing in the presence of a magnetic field.
An exchange anisotropic magnetic field takes place through exchange
coupling at the interface between the first pinned magnetic layer
81 and the antiferromagnetic layer 80. The magnetization direction
of the first pinned magnetic layer 81 is thus pinned in the Y
direction. When the magnetization direction of the first pinned
magnetic layer 81 is pinned in the Y direction, the magnetization
direction of the second pinned magnetic layer 83, separated from
the first pinned magnetic layer 81 by the intervening nonmagnetic
material layer 82, is pinned to be antiparallel to the
magnetization direction of the first pinned magnetic layer 81. The
direction of the sum of the magnetic moments of the first and
second free magnetic layers 81 and 83 becomes the magnetization of
the pinned magnetic layer P.
[0320] The first free magnetic layer 85 and the second free
magnetic layer 87, having different magnetic moments, are laminated
with the nonmagnetic material layer 86 interposed therebetween, and
function as a single free magnetic layer F.
[0321] The first free magnetic layer 85 and the second free
magnetic layer 87 are manufactured of the same material with
thicknesses thereof made different so that the two layers have
different magnetic moments.
[0322] In the spin-valve type thin-film device shown in FIG. 12,
again, the first free magnetic layer 85 and the second free
magnetic layer 87, which are in a ferrimagnetic state with
magnetization directions thereof being antiparallel, namely
different from each other by 180 degrees, achieve the same effect,
which can be provided by the use of a thin free magnetic layer F.
This arrangement reduces the saturation magnetization of the entire
free magnetic layer F, causing the magnetization of the free
magnetic layer F to easily vary, and thereby improving the magnetic
field detection sensitivity of the magnetoresistive-effect
device.
[0323] The direction of the sum of the magnetic moments of the
first free magnetic layer 85 and the second free magnetic layer 87
becomes the magnetization direction of the free magnetic layer
F.
[0324] The hard bias layers 89 and 89 are magnetized in the X
direction (i.e., the direction of the track width), and the
magnetization direction of the free magnetic layer F is aligned in
the X direction under the bias magnetic field in the X direction
given by the hard bias layers 89 and 89.
[0325] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0326] In twelfth embodiment again, the sensitive region E and the
insensitive regions D and D of the multilayer film 202 are measured
using the micro track profile method. Referring to FIG. 12, the
portion, having the width dimension T48, of the multilayer film 202
is the sensitive region E, and the portions, each having the width
dimension T49, are the insensitive regions D and D.
[0327] In the sensitive region E, the magnetization direction of
the pinned magnetic layer P is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer P and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer P. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation. However, those which directly contribute to the
variation in the electrical resistance (i.e., the reproduction
output) are a relative angle made between the magnetization
direction of the second pinned magnetic layer 83 and the
magnetization direction of the first free magnetic layer 85. These
magnetization directions are preferably perpendicular with a sense
current conducted in the absence of a signal magnetic field.
[0328] The electrode layers 91 and 91 formed on both sides of the
multilayer film 202 extend over the multilayer film 202. The width
dimension of the top surface of the multilayer film 202 not covered
with the electrode layers 91 and 91 is the optical read track width
O-Tw.
[0329] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 91 and 91, is a width dimension T48, which is also the
dimension of the sensitive region E.
[0330] In the twelfth embodiment, the electrode layers 91 and 91
formed on the multilayer film 202 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0331] It is not a requirement that the electrode layers 91 and 91
formed above the multilayer film 202 fully cover the insensitive
regions D and D, and the electrode layer 91 may be narrower than
the insensitive region D. In this case, the optical read track
width O-Tw becomes larger than the magnetic read track width
M-Tw.
[0332] The percentage of the sense current flowing from the
electrode 91 to the multilayer film 202 without passing through the
hard bias layers 89 and 89 is increased in this invention.
[0333] The electrode layers 91 and 91 extending over the
insensitive regions D and D prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0334] The width dimension T50 of each of the electrode layers 91
and 91 extending over the insensitive region D of the multilayer
film 202 preferably falls within a range from 0 .mu.m to 0.08
.mu.m. More preferably, the width dimension T50 of each of the
electrode layers 91 and 91 falls within a range from 0.05 .mu.m to
0.08 .mu.m.
[0335] The angle .theta.12 made between the top surface of the
multilayer film 202 with the protective layer 15 removed, namely,
the top surface 80a of the antiferromagnetic layer 80 in FIG. 12,
and an end face 91a of the electrode layer 91 extending over the
insensitive region of the multilayer film 202 is preferably 20
degrees or greater, and more preferably 25 degrees or greater. This
arrangement prevents the sense current from shunting into the
insensitive region, thereby controlling the generation of
noise.
[0336] To prevent a short which is likely to occur between the
electrode layers 91 and 91 and a top shield layer of a soft
magnetic material when the top shield layer is deposited over the
protective layer 15 and the electrode layers 91 and 91, the angle
.theta.12 made between the top surface 80a and the end face 91a is
preferably 60 degrees or smaller, and more preferably, 45 degrees
or smaller.
[0337] Referring to FIG. 12, a magnetic coupling junction M between
the multilayer film 202 and each of the hard bias layers 89 and 89
is fabricated of an interface with the end face of only the second
free magnetic layer 87, of both the first free magnetic layer 85
and the second free magnetic layer 87. This arrangement controls
the disturbance in the magnetization direction on both end portions
in the free magnetic layer, permitting the width dimension T48 of
the sensitive region E to be enlarged.
[0338] As shown in FIG. 12, the protective layer 15 is deposited
where the multilayer film 202 has no electrode layers 91 and 91
formed thereon. The electrode layers 91 and 91 are connected to the
antiferromagnetic layer 80 with no protective layer 15 interposed
therebetween.
[0339] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 91 and 91 are
laminated on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0340] FIG. 13 is a cross-sectional view showing the
magnetoresistive-effect device of a thirteenth embodiment of the
present invention, viewed from an ABS side thereof.
[0341] This spin-valve type thin-film device is a so-called dual
spin-valve type thin-film device, which includes a nonmagnetic
material layer 106, a first free magnetic layer 105 and a second
free magnetic layer 107, respectively lying under and over the
nonmagnetic material layer 106, nonmagnetic electrically conductive
layers 104 and 108, respectively lying under the first free
magnetic layer 105 and over the second free magnetic layer 107, a
first pinned magnetic layer 103 and a third pinned magnetic layer
109, respectively lying under the nonmagnetic electrically
conductive layer 104 and over the nonmagnetic electrically
conductive layer 108, nonmagnetic layers 102 and 110, respectively
lying under the first pinned magnetic layer 103 and over the third
pinned magnetic layer 109, a second pinned magnetic layer 101 and a
fourth pinned magnetic layer 111, respectively lying under the
nonmagnetic material layer 102 and over the nonmagnetic material
layer 110, and antiferromagnetic layers 100 and 112, respectively
lying under the second pinned magnetic layer 101 and over the
fourth pinned magnetic layer 111. The dual spin-valve type
thin-film device provides a reproduction output higher in level
than that of the spin-valve type thin-film devices (i.e., so-called
single spin-valve type thin-film devices) shown in FIG. 11 through
FIG. 13. The layer lying at the bottom is a substrate 10, while the
layer lying on the top is a protective layer 15. The laminate,
composed of the layers from the substrate 10 through the protective
layer 15, constitutes a multilayer film 203.
[0342] Referring to FIG. 13, the antiferromagnetic layer 100
extends on and along the substrate 10 in the X direction with a
central portion thereof projected upward.
[0343] In the thirteenth embodiment, the antiferromagnetic layers
100 and 112 are made of a Pt--Mn (platinum-manganese) alloy.
Instead of the Pt--Mn alloy, the antiferromagnetic layers 100 and
112 may be made of an X--Mn alloy where X is a material selected
from the group consisting of Pd, Ir, Rh, Ru, and alloys thereof, or
a Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0344] The first free magnetic layer 105, the second free magnetic
layer 107, the first pinned magnetic layer 103, the second pinned
magnetic layer 101, the third pinned magnetic layer 109, and the
fourth pinned magnetic layer 111 are made of an Ni--Fe
(nickel-iron) alloy, Co (cobalt), an Fe--Co (iron-cobalt) alloy, or
an Fe--Co--Ni alloy, and the nonmagnetic electrically conductive
layers 104 and 108 are made of a low electrical-resistance
nonmagnetic electrically conductive material, such as Cu
(copper).
[0345] Referring to FIG. 13, each of metallic layers 113 and 113,
made of Cr or the like, and functioning as a buffer layer or a
alignment layer, extends from a horizontal portion thereof
coextending a width dimension T51 of the antiferromagnetic layer
100 in the X direction, rising along the side end faces of the
second pinned magnetic layer 101, the nonmagnetic material layer
102, the first pinned magnetic layer 103, the nonmagnetic
electrically conductive layer 104, and the first free magnetic
layer 105. The use of the metallic layers 113 and 113 helps
increase the strength of the bias magnetic field created by hard
bias layers 114 and 114 to be described later.
[0346] Deposited on top of the metallic layers 113 and 113 are the
hard bias layers 114 and 114 which are made of a Co--Pt
(cobalt-platinum) alloy or a Co--Cr--Pt (cobalt-chromium-platinum)
alloy.
[0347] Intermediate layers 115 and 115, made of a nonmagnetic
material such as Ta, are respectively deposited on the hard bias
layers 114 and 114. Electrode layers 116 and 116, made of Cr, Au,
Ta, or W, are respectively deposited on top of the intermediate
layers 115 and 115.
[0348] Since the antiferromagnetic layer 100 extends beneath and
along the hard bias layers 114 and 114 as shown in FIG. 13, the
thickness of the hard bias layers 114 and 114 can be made thinner.
The hard bias layers 114 and 114 are thus easily produced using a
sputtering technique.
[0349] Referring to FIG. 13, the first pinned magnetic layer 103
and the second pinned magnetic layer 101, having different magnetic
moments, are laminated to each other with the nonmagnetic material
layer 102 interposed therebetween, and function as a single pinned
magnetic layer P.sub.1. The third pinned magnetic layer 109 and the
fourth pinned magnetic layer 111, having different magnetic
moments, are laminated to each other with the nonmagnetic material
layer 110 interposed therebetween, and function as a single pinned
magnetic layer P.sub.2.
[0350] The first pinned magnetic layer 103 and the second pinned
magnetic layer 101 are in a ferrigmagnetic state with magnetization
directions thereof being antiparallel, namely, 180 degrees opposite
from each other, and the magnetization direction of the first
pinned magnetic layer 103 and the magnetization direction of the
second material layer 101 mutually pin each other. The
magnetization direction of the pinned magnetic layer P.sub.1, as a
whole, is advantageously stabilized in one direction.
[0351] Referring to FIG. 13, the first pinned magnetic layer 103
and the second pinned magnetic layer 101 are manufactured of the
same material with thicknesses thereof made different so that the
two layers have different magnetic moments.
[0352] The third pinned magnetic layer 109 and the fourth pinned
magnetic layer 111 are in a ferrimagnetic state with the
magnetization directions thereof being antiparallel, namely, 180
degrees opposite from each other, and the magnetization direction
of the third pinned magnetic layer 109 and the magnetization
direction of the fourth pinned magnetic layer 111 mutually pin each
other.
[0353] The nonmagnetic material layers 102 and 110 are preferably
made of a material selected from the group consisting of Ru, Rh,
Ir, Cr, Re, Cu, and alloys thereof.
[0354] The second pinned magnetic layer 101 and the fourth pinned
magnetic layer 111 are respectively deposited on and in contact
with the antiferromagnetic layers 100 and 112, and are subjected to
annealing under the presence of a magnetic field. An anisotropic
magnetic field occurs through exchange coupling at each of the
interfaces between the second pinned magnetic layer 101 and the
antiferromagnetic layer 100, and between the fourth pinned magnetic
layer 111 and the antiferromagnetic layer 112.
[0355] The magnetization direction of the second pinned magnetic
layer 101 is pinned in the Y direction. When the magnetization
direction of the second pinned magnetic layer 101 is pinned in the
Y direction, the magnetization direction of the first pinned
magnetic layer 103, separated from the second pinned magnetic layer
101 by the nonmagnetic material layer 102, is pinned to be
antiparallel to the magnetization direction of the second pinned
magnetic layer 101. The direction of the sum of the magnetic
moments of the second pinned magnetic layer 101 and the first
pinned magnetic layer 103 becomes the direction of the pinned
magnetic layer P.sub.1.
[0356] When the magnetization direction of the second pinned
magnetic layer 101 is pinned in the Y direction, the magnetization
direction of the fourth pinned magnetic layer 111 is preferably
pinned to be antiparallel to the Y direction. Then, the
magnetization direction of the third pinned magnetic layer 109,
separated from the fourth pinned magnetic layer 111 by the
nonmagnetic material layer 110, is pinned to be antiparallel to the
magnetization direction of the fourth pinned magnetic layer 111,
namely, pinned in the Y direction. The direction of the sum of the
magnetic moments of the fourth pinned magnetic layer 111 and the
third pinned magnetic layer 109 becomes the magnetization direction
of the pinned magnetic layer P.sub.2.
[0357] The first pinned magnetic layer 103 and the third pinned
magnetic layer 109, which are separated from each other by the
first free magnetic layer 105, the nonmagnetic layer 106, and the
second free magnetic layer 107, are in an antiparallel state with
the magnetization directions thereof being opposite by 180
degrees.
[0358] Referring to FIG. 13, as will be discussed later, a free
magnetic layer F is formed of the first free magnetic layer 105 and
the second free magnetic layer 107, both laminated with the
nonmagnetic layer 106 interposed therebetween. The first free
magnetic layer 105 and the second free magnetic layer 107 are in a
ferrimagnetic state with the magnetization directions thereof being
antiparallel to each other.
[0359] The first free magnetic layer 105 and the second free
magnetic layer 107 change magnetization directions thereof under
the influence of an external magnetic field while keeping the
ferrimagnetic state. If the first pinned magnetic layer 103 and the
third pinned magnetic layer 109 are in an antiparallel state with
the magnetization directions thereof being opposite by 180 degrees,
the rate of change in resistance of the layers above the free
magnetic layer F becomes equal to the rate of change in resistance
of the layers below the free magnetic layer F.
[0360] Furthermore, the magnetization direction of the pinned
magnetic layer P.sub.1 and the magnetization direction of the
pinned magnetic layer P.sub.2 are preferably antiparallel to each
other.
[0361] The magnitude of the magnetic moment of the second pinned
magnetic layer 101 pinned in the Y direction is set to be larger
than the magnitude of the magnetic moment of the first pinned
magnetic layer 103 to align the magnetization direction of the
pinned magnetic layer P.sub.1 in the Y direction. On the other
hand, the magnitude of the magnetic moment of the third pinned
magnetic layer 109 pinned in the Y direction is set to be smaller
than the magnitude of the magnetic moment of the fourth pinned
magnetic layer 111 to align the magnetization direction of the
pinned magnetic layer P.sub.2 to be antiparallel to the Y
direction.
[0362] In this arrangement, the direction of the magnetic field,
which is created when the sense current flows in the X direction,
coincides with the magnetization direction of the pinned magnetic
layer P.sub.1 and the magnetization direction of the pinned
magnetic layer P.sub.2. This arrangement stabilizes the
ferrimagnetic state of the first pinned magnetic layer 103 and the
second pinned magnetic layer 101 and the ferrimagnetic state of the
third pinned magnetic layer 109 and the fourth pinned magnetic
layer 111.
[0363] The first free magnetic layer 105 and the second free
magnetic layer 107 are designed to have different magnetic moments.
Here again, the first free magnetic layer 105 and the second free
magnetic layer 107 are manufactured of the same material with
thicknesses thereof made different so that the two layers have
different magnetic moments.
[0364] The nonmagnetic material layers 102, 106, and 116 are made
of a material selected from the group consisting of Ru, Rh, Ir, Cr,
Re, Cu, and alloys thereof.
[0365] Referring to FIG. 13, the first free magnetic layer 105 and
the second free magnetic layer 107 are laminated with the
nonmagnetic layer 106 interposed therebetween, and function as a
single free magnetic layer F.
[0366] The first free magnetic layer 105 and the second free
magnetic layer 107, which are in a ferrimagnetic state with the
magnetization directions thereof being antiparallel, namely
different from each other by 180 degrees, achieve the same effect,
which can be provided by the use of a thin free magnetic layer F.
This arrangement reduces the saturation magnetization of the entire
free magnetic layer F, causing the magnetization of the free
magnetic layer F to easily vary, and thereby improving the magnetic
field detection sensitivity of the magnetoresistive-effect
device.
[0367] The direction of the sum of the magnetic moments of the
first free magnetic layer 105 and the second free magnetic layer
107 becomes the magnetization direction of the free magnetic layer
F.
[0368] The hard bias layers 114 and 114 are magnetized in the X
direction (i.e., the direction of the track width), and the
magnetization direction of the free magnetic layer F is aligned in
the X direction under the bias magnetic field in the X direction
given by the hard bias layers 114 and 114.
[0369] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0370] In the thirteenth embodiment again, the sensitive region E
and the insensitive regions D and D of the multilayer film 203 are
measured using the micro track profile method. Referring to FIG.
13, the portion, having the width dimension T52, centrally
positioned in the multilayer film 203 is the sensitive region E,
and the portions, each having the width dimension T53, on both
sides of the sensitive region E are the insensitive regions D and
D.
[0371] In the sensitive region E, the magnetization directions of
the pinned magnetic layers P.sub.1 and P.sub.2 are correctly
aligned in a direction parallel to the Y direction, and the
magnetization of the free magnetic layer F is correctly aligned in
the X direction. The pinned magnetic layers P.sub.1 and P.sub.2 and
the free magnetic layer F are perpendicular to each other in
magnetization direction. The magnetization of the free magnetic
layer F varies sensitively in response to an external magnetic
field from the recording medium. An electrical resistance varies in
accordance with the relationship between the variation in the
magnetization direction of the free magnetic layer F and the pinned
magnetic field of the pinned magnetic layers P.sub.1 and P.sub.2. A
leakage magnetic field from the recording medium is thus detected
in response to a variation in voltage due to the electrical
resistance variation. However, those which directly contribute to
the variation in the electrical resistance (i.e., the reproduction
output) are a relative angle made between the magnetization
direction of the first pinned magnetic layer 103 and the
magnetization direction of the first free magnetic layer 105, and a
relative angle made between the magnetization direction of the
third pinned magnetic layer 109 and the magnetization direction of
the second free magnetic layer 107. These magnetization directions
are preferably perpendicular with a sense current conducted in the
absence of a signal magnetic field.
[0372] Referring to FIG. 13, in this invention, electrode layers
116 and 116 are respectively formed on top of intermediate layers
115 and 115, which in turn are respectively formed on top of the
hard bias layers 114 and 114 on both sides of the multilayer film
203. The electrode layers 116 and 116 extend over the insensitive
regions D and D of the multilayer film 203. The electrode layers
116 and 116 are made of a Cr, Au, Ta, or W film.
[0373] The width dimension of the top surface of the multilayer
film 203 not covered with the electrode layers 116 and 116 is
defined as the optical read track width O-Tw. The width dimension
T52 of the sensitive region E not covered with the electrode layers
116 and 116 is defined as the magnetic read track width M-Tw. In
the thirteenth embodiment, the electrode layers 116 and 116
extending over the multilayer film 203 fully cover the insensitive
regions D and D. The optical read track width O-Tw is thus
approximately equal to the magnetic read track width M-Tw (i.e.,
the width dimension of the sensitive region E).
[0374] It is not a requirement that the electrode layers 116 and
116 formed above the multilayer film 203 fully cover the
insensitive regions D and D, and the width dimension T54 of each of
the electrode layers 116 and 116 may be narrower than the
insensitive region D. In this case, the optical read track width
O-Tw becomes larger than the magnetic read track width M-Tw.
[0375] This arrangement makes it easier for the sense current to
directly flow from the electrode layers 116 and 116 into the
multilayer film 203 without passing through the hard bias layers
114 and 114. With the electrode layers 116 and 116 respectively
extending over the insensitive regions D and D, the junction area
between the multilayer film 203 and the electrode layers 116 and
116 is increased, reducing the direct current resistance (DCR) and
thereby improving the reproduction characteristics.
[0376] Furthermore, the electrode layers 116 and 116, respectively
extending over the insensitive regions D and D, prevent the sense
current flowing into the insensitive regions D and D, thereby
controlling the generation of noise.
[0377] Referring to FIG. 13, the width dimension T54 of each of the
electrode layers 116 and 116 extending over the insensitive regions
D and D of the multilayer film 203 preferably falls within a range
from 0 .mu.m to 0.08 .mu.m. More preferably, the width dimension
T54 falls within a range from 0.05 .mu.m to 0.08 .mu.m.
[0378] The angle .theta.13 made between the top surface of the
multilayer film 203 with the protective layer 15 removed, namely,
the top surface 112a of the antiferromagnetic layer 112 in FIG. 13,
and an end face 116a of the electrode layer 116 extending over the
insensitive region of the multilayer film 203 is preferably 20
degrees or greater, and more preferably 25 degrees or greater. This
arrangement prevents the sense current from shunting into the
insensitive region, thereby controlling the generation of
noise.
[0379] To prevent a short which is likely to occur between the
electrode layers 116 and 116 and a top shield layer when the top
shield layer is deposited over the protective layer 15 and the
electrode layers 116 and 116, the angle .theta.13 made between the
top surface 112a and the end face 116a is preferably 60 degrees or
smaller, and more preferably, 45 degrees or smaller.
[0380] Referring to FIG. 13, a magnetic coupling junction M between
the multilayer film 203 and each of the hard bias layers 114 and
114 is fabricated of an interface with the end face of only the
first free magnetic layer 105, of both the first free magnetic
layer 105 and the second free magnetic layer 107. This arrangement
controls the disturbance in the magnetization direction on both end
portions in each of the free magnetic layers, permitting the width
dimension T52 of the sensitive region E to be enlarged.
[0381] As shown in FIG. 13, the protective layer 15 is formed where
the multilayer film 203 has no electrode layers 116 and 116
deposited thereon. The electrode layers 116 and 116 are connected
to the antiferromagnetic layer 112 with no protective layer 15
interposed therebetween.
[0382] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 116 and 116 are
deposited on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0383] FIG. 14 is a cross-sectional view of the
magnetoresistive-effect device of a fourteenth embodiment of the
present invention, viewed from an ABS side thereof.
[0384] A magnetoresistive-effect device shown in FIG. 14 is an AMR
(anisotropic magnetoresistive) device, and its layer structure is
identical to that of the AMR device shown in FIG. 8.
[0385] In this embodiment again, the sensitive region E and the
insensitive regions D and D of the multilayer film 61 are measured
using the micro track profile method. The portion, having the width
dimension T19, centrally positioned on a multilayer film 61 is the
sensitive region E, and the portions, each having the width
dimension T20, are the insensitive regions D and D.
[0386] The difference of the AMR device shown in FIG. 14 from the
AMR device shown in FIG. 8 lies in that a protective layer 55 is
formed where the multilayer film 61 has no junction with electrode
layers 120 and 120 and that a magnetoresistive layer 54 is directly
connected to the electrode layers 120 and 120 with no protective
layer 55 interposed therebetween.
[0387] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 120 and 120 are
laminated on the protective layer 55, improving the characteristics
of the magnetoresistive-effect device.
[0388] Referring to FIG. 14, the electrode layers 120 and 120 are
formed to extend over the multilayer film 61. The width dimension
of the top surface of the multilayer film 61 having no electrode
layer 120 thereon is the optical read track width O-Tw, and the
width dimension of the sensitive region E not covered with the
electrode layer 120 is the magnetic read track width M-Tw. In this
embodiment, the electrode layers 120 and 120 extending over the
multilayer film 61 fully cover the insensitive regions D and D. The
optical read track width O-Tw is thus approximately equal to the
magnetic read track width M-Tw.
[0389] It is not a requirement that the electrode layers 120 and
120 fully cover the insensitive regions D and D, and the width
dimension T55 of the electrode layer 120 extending over the
multilayer film 61 is smaller than the insensitive region D. In
this case, the optical read track width O-Tw becomes larger than
the magnetic read track width M-Tw.
[0390] The width dimension T55 of each of the electrode layers 120
and 120 extending over the insensitive regions D and D of the
multilayer film 61 preferably falls within a range from 0 .mu.m to
0.08 .mu.m. More preferably, the width dimension T21 falls within a
range from 0.05 .mu.m to 0.08 .mu.m.
[0391] The angle .theta.14 made between the top surface 54a of the
magnetoresistive layer and an end face 120a of the electrode layer
120 extending over the insensitive region of the multilayer film 61
is preferably 20 degrees or greater, and more preferably 25 degrees
or greater. This arrangement prevents the sense current from
shunting into the insensitive region, thereby controlling the
generation of noise.
[0392] If the angle .theta.14 made between the top surface 54a and
the end face 120a is too large, a short is likely to occur between
the electrode layer 120 and a top shield layer of a soft magnetic
material when the top shield layer is deposited over the protective
layer 55 and the electrode layers 120 and 120. The angle .theta.14
made between the top surface 54a and the end face 120a is
preferably 60 degrees or smaller, and more preferably, 45 degrees
or smaller.
[0393] In the AMR device, the hard bias layers 56 and 56 are
magnetized in the X direction as shown, and the magnetoresistive
layer 54 is supplied with the bias magnetic field in the X
direction by the hard bias layers 56 and 56. Furthermore, the
magnetoresistive layer 54 is supplied with the bias field in the Y
direction by the soft magnetic layer 52. With the magnetoresistive
layer 54 supplied with the bias magnetic fields in the X direction
and Y direction, a variation in magnetization thereof in response
to a variation in the magnetic field becomes linear.
[0394] The sense current from the electrode layers 120 and 120 is
directly fed to the magnetoresistive layer 54 in the sensitive
region E. The direction of the advance of the recording medium is
aligned with the Z direction. When a leakage magnetic field from
the recording medium in the Y direction is applied, the
magnetization direction of the magnetoresistive layer 54 varies,
causing a variation in the resistance. The resistance variation is
then detected as a voltage variation.
[0395] By using a method, to be discussed later, for manufacturing
a magnetoresistive-effect device, the film thickness of the region
of the hard bias layer in contact with the multilayer is made thin,
and the top surface of the hard bias layer close to the multilayer
film is, downwardly, inclined or curved toward the multilayer film
as shown in the magnetoresistive-effect devices shown in FIG. 1
through FIG. 14.
[0396] When the top surface of the hard bias layer is projected
upward toward the multilayer film in the conventional
magnetoresistive-effect device as shown in FIG. 33, a leakage
magnetic field or a loop magnetic field takes place around the
projected portion, making the magnetization direction of the free
magnetic layer less stable.
[0397] If the top surface of the hard bias layer is, downwardly,
inclined or curved toward the multilayer film as shown in FIG. 1
through FIG. 14, the generation of the leakage magnetic field and
the loop magnetic field is prevented, and the magnetization
direction of the free magnetic layer is thus stabilized.
[0398] The manufacturing method for manufacturing the
magnetoresistive-effect devices shown in FIG. 1 through FIG. 14 is
now discussed referring to the drawings.
[0399] Referring to FIG. 15, a multilayer film 161 of the
magnetoresistive-effect device is formed on a substrate 160. The
multilayer film 161 can be any of the multilayer films of the
single spin-valve type thin-film devices shown in FIG. 1 through
FIG. 5, and FIG. 11 through FIG. 12, the multilayer films of the
dual spin-valve type thin-film devices shown in FIG. 6, FIG. 7 and
FIG. 13, and the multilayer films of the AMR devices shown in FIG.
8, FIG. 9 and FIG. 14.
[0400] To form the antiferromagnetic layers 30, 70, 80, and 100 in
extended forms thereof in the X direction respectively shown in
FIG. 4, FIG. 5, FIG. 10, and FIG. 11, an etch rate and etch time
are controlled to leave the lateral portions of the
antiferromagnetic layers 30, 70, 80, and 100 when the sides of the
multilayer film 161, shown in FIG. 15, are etched away.
[0401] When the multilayer film 161 is a multilayer film for a
single spin-valve type thin-film device or a dual spin-valve type
thin-film device, the antiferromagnetic layer in the multilayer
film 161 is preferably made of a PtMn alloy, or may be made of an
X--Mn alloy where X is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof, or a Pt--Mn--X'
alloy where X' is a material selected from the group consisting of
Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof. When the
antiferromagnetic layer is made of one of the above-cited
materials, the antiferromagnetic layer needs to be subjected to a
heat treatment to generate an exchange coupling magnetic field in
the interface with the pinned magnetic layer.
[0402] FIG. 33 shows a conventional magnetoresistive-effect device
having its hard bias layers and electrode layers on only both sides
of the multilayer film. The width dimension A of the top surface of
the multilayer film of the conventional magnetoresistive-effect
device is measured using an optical microscope as shown in FIG. 31.
The magnetoresistive-effect device is then scanned across a micro
track having a signal recorded thereon, on a recording medium in
the direction of the track width, and a reproduction output is
detected. A top width dimension of B giving an output equal to or
greater than 50% of a maximum reproduction output is defined as the
sensitive region E and a top width dimension of C giving an output
smaller than 50% of the maximum reproduction output is defined as
the insensitive region D.
[0403] Based on these measurement results, a lift-off resist layer
162 is formed on the multilayer film 161, paying attention to the
width dimension C of the insensitive regions D and D measured
through the micro track profile method. Referring to FIG. 15,
undercuts 162a and 162a are formed on the underside of the resist
layer 162. The undercuts 162a and 162a are formed above the
insensitive regions D and D, and the sensitive region E of the
multilayer film 161 is fully covered with the resist layer 162.
[0404] In a next manufacturing step shown in FIG. 16, both sides of
the multilayer film 161 are etched away.
[0405] When one of the magnetoresistive-effect devices shown in
FIG. 11 through FIG. 14 is manufactured, the protective layer is
formed on top of the multilayer film 161, and the resist layer 162
is formed on top of the protective layer. The portions of the
protective layer, which come just below the undercuts 162a and 162a
of the resist layer 162, namely, the portions of the protective
layer which are not in direct contact with the resist layer 162,
are removed through an obliquely entering ion milling beam to
expose the layer beneath the protective layer.
[0406] In a manufacturing step shown in FIG. 17, hard bias layers
163 and 163 are deposited on both sides of the multilayer film 161.
In this invention, the sputtering technique, used to form the hard
bias layers 163 and 163 and electrode layers 165 and 165 to be
formed subsequent to the formation of the hard bias layers 163 and
163, is preferably at least one sputtering technique selected from
an ion-beam sputtering method, a long-throw sputtering method, and
a collimation sputtering method.
[0407] In accordance with the present invention, as shown in FIG.
17, a substrate 160 having the multilayer film 161 formed thereon
is placed normal to a target 164 having the same composition as
that of the hard bias layers 163 and 163. In this setup, the hard
bias layers 163 and 163 are grown in a direction normal to the
multilayer film 161 using the ion-beam sputtering method, for
instance. The hard bias layers 163 and 163 are not grown into the
undercuts 162a and 162a of the resist layer 162 arranged on the
multilayer film 161. Less sputter particles are deposited in the
regions of the hard bias layers 163 and 163 in contact with the
multilayer film 161, because of the overhang by both end portions
of the resist layer 162. The thickness of the hard bias layers 163
and 163 is thinner in the regions thereof in contact with the
multilayer film 161, and the top surface of the hard bias layers
163 and 163 are downwardly inclined or curved toward the multilayer
film 161 as shown. Referring to FIG. 17, a layer 163a having the
same composition as that of the hard bias layers 163 and 163 is
formed on top of the resist layer 162.
[0408] In the manufacturing step shown in FIG. 17, the hard bias
layers 163 and 163 are preferably formed so that the height
position of the top edge or the bottom edge (in the Z direction) of
the magnetic coupling junction between the multilayer film 161 and
each of the hard bias layers 163 and 163 is at the same level as
the height position of the top surface or the bottom surface of the
free magnetic layer or the magnetoresistive-effect layer in the
direction of the advance of the recording medium.
[0409] It is sufficient if each of the hard bias layers 163 and 163
is magnetically coupled with the free magnetic layer only or the
magnetoresistive-effect layer only. The influence of the magnetic
field generated from the bias layers 163 and 163, on the
magnetization direction of the pinned magnetic layer, is controlled
if the hard bias layers 163 and 163 remain magnetically uncoupled
with the pinned magnetic layer.
[0410] If the multilayer film 161 includes a free magnetic layer
which is composed of a plurality of soft magnetic thin-film layers
having different magnetic moments and separated from each other by
nonmagnetic material layers, like the multilayer film of one of the
thin-film devices shown in FIG. 10 through FIG. 13, the hard bias
layers 163 and 163 are preferably formed so that the magnetic
coupling junction between the multilayer film 161 and each of the
hard bias layers 163 and 163 is fabricated of an interface with the
end face of only one of the plurality of the soft magnetic
thin-film layers forming the free magnetic layer.
[0411] If the magnetic coupling junction between the multilayer
film 161 and each of the hard bias layers 161 and 161 is fabricated
of an interface with the end face of only one of the plurality of
the soft magnetic thin-film layers forming the free magnetic layer,
the magnetization direction of the soft magnetic thin-film layer on
both end portions is free from disturbance.
[0412] In a manufacturing step shown in FIG. 18, the electrode
layers 165 and 165 are obliquely grown on the hard bias layers 163
and 163 at an angle to the multilayer film 161. In this case, the
electrode layers 165 and 165 are grown into the undercuts 162a and
162a formed on the underside of the resist layer 162 arranged on
top of the multilayer film 161.
[0413] Referring to FIG. 18, a target 166 having the same
composition as that of the electrode layer 165 is inclined at an
angle to the substrate 160 having the multilayer film 161 formed
thereon, and the electrode layers 165 and 165 are grown on the hard
bias layers 163 and 163 using the ion-beam sputtering method while
moving the target 166 transversely across the substrate 160. The
electrode layers 165 and 165 sputtered at an angle to the
multilayer film 161 are formed not only on the hard bias layers 163
and 163 but also into the undercuts 162a and 162a of the resist
layer 162. Specifically, the electrode layers 165 and 165 formed
within the undercuts 162a and 162a are grown on the insensitive
regions D and D of the multilayer film 161.
[0414] Referring to FIG. 18, the target 166 is moved at an angle
with respect to a fixed substrate 160. Alternatively, the substrate
160 may be moved at an angle with respect to a fixed target 166. As
shown in FIG. 18, a layer 165a having the same composition as the
electrode layers 165 and 165 is deposited on top of the layer 163a
on the resist layer 162.
[0415] When the portions of the protective layer, formed on top of
the multilayer film 161 and having no contact with the resist layer
162, are removed to expose the underlayers beneath the protective
layer, the electrode layers 165 and 165 are deposited on and in
direct contact with the free magnetic layer, the antiferromagnetic
layer or the magnetoresistive-effect layer beneath the protective
layer as in the magnetoresistive-effect devices shown in FIG. 11
through FIG. 14.
[0416] In a manufacturing step shown in FIG. 19, the resist layer
162 shown in FIG. 18 is removed through a lift-off process, and
this completes a magnetoresistive-effect device having the
electrode layers 165 and 165 formed on top of the insensitive
regions D and D of the multilayer film 161.
[0417] In the film forming process of the electrode layers 165 and
165, the angle .theta. made between the end face 165b of the
electrode layer 165 formed into the undercut 162a and the top
surface 161a of the multilayer film 161 is preferably 20 degrees or
greater, and more preferably 25 degrees or greater. This
arrangement prevents the sense current from shunting into the
insensitive region, thereby controlling the generation of
noise.
[0418] In the manufacturing method shown in FIG. 15 through FIG.
19, increasing the angle .theta. made between the top surface 161a
and the end face 165b is difficult. If the angle .theta. made
between the top surface 161a and the end face 165b is too large, a
short is likely to occur between the electrode layers 165 and 165
and a top shield layer of a soft magnetic material when the top
shield layer is deposited over the multilayer film 161 and the
electrode layers 165 and 165. The angle .theta. made between the
top surface 161a and the end face 165b is preferably 60 degrees or
smaller, and more preferably, 45 degrees or smaller.
[0419] FIG. 20 is a cross-sectional view showing the
magnetoresistive-effect device of a fifteenth embodiment of the
present invention, viewed from an ABS side thereof.
[0420] The magnetoresistive-effect device shown in FIG. 20
includes, on the multilayer film 200 having the same construction
as the one in the magnetoresistive-effect device shown in FIG. 10,
a laminated insulator layer 131 constructed of Al.sub.2O.sub.3, and
electrode layers 130 and 130 with end their faces 130a and 130a in
direct contact with both sides of the insulator layer 131.
[0421] The construction and materials of the layers of the
multilayer film 200 remain the same as those of the
magnetoresistive-effect device shown in FIG. 10.
[0422] Metallic layers 76 and 76, hard bias layers 77 and 77 and
intermediate layers 78 and 78, coextending the width dimension T56
of the antiferromagnetic layer 70 extending in the X direction, are
identical, in construction and material, to the counterparts in the
magnetoresistive-effect device shown in FIG. 10.
[0423] In the magnetoresistive-effect device shown in FIG. 20, the
first free magnetic layer 73 and the second free magnetic layer 75,
having different magnetic moments, are in a ferrimagnetic state
with the magnetization directions thereof being antiparallel. The
first free magnetic layer 73 and the second free magnetic layer 75,
separated from each other by the nonmagnetic material layer 74,
function as a single free magnetic layer F.
[0424] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0425] In fifteenth embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 200 are
measured using the micro track profile method. Referring to FIG.
20, the portion, having the width dimension T57, of the multilayer
film 200 is the sensitive region E, and the portions, each having
the width dimension T58, on both sides of the sensitive region E
are the insensitive regions D and D.
[0426] In the sensitive region E, the magnetization direction of
the pinned magnetic layer P is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer P and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer P. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation. However, those which directly contribute to the
variation in the electrical resistance (i.e., the reproduction
output) are a relative angle made between the magnetization
direction of the pinned magnetic layer 71 and the magnetization
direction of the first free magnetic layer 73. These magnetization
directions are preferably perpendicular with a sense current
conducted in the absence of a signal magnetic field. In other
words, the variation in the electrical resistance is determined by
the relative angle made between the magnetization directions of the
free magnetic layer 73 and the pinned magnetic layer 71, which are
separated from each other by the nonmagnetic electrically
conductive layer 72.
[0427] The electrode layers 130 and 130 formed above the multilayer
film 200 extend over the multilayer film 200. The width dimension
of the top surface of the multilayer film 200 not covered with the
electrode layers 130 and 130 is the optical read track width
O-Tw.
[0428] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 130 and 130, is a width dimension T57, which is also the
dimension of the sensitive region E.
[0429] In the fifteenth embodiment, the electrode layers 130 and
130 formed on the multilayer film 200 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0430] It is not a requirement that the electrode layers 130 and
130 formed above the multilayer film 200 fully cover the
insensitive regions D and D, and the electrode layer 130 may be
narrower than the insensitive region D. In this case, the optical
read track width O-Tw becomes larger than the magnetic read track
width M-Tw.
[0431] The percentage of the sense current flowing from the
electrodes 130 and 130 to the multilayer film 200 without passing
through the hard bias layers 77 and 77 is increased.
[0432] The electrode layers 130 and 130 extending over the
insensitive regions D and D prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0433] When the magnetoresistive-effect device shown in FIG. 20 is
produced using the manufacturing method to be described later, the
angle .theta.20 made between the end face 130a of the electrode
layer 130, extending over the insensitive region of the multilayer
film 200 and in contact with the insulator layer 131, and the top
surface 15a of the protective layer 15, is set to be 60 degrees or
greater, or 90 degrees or greater. This arrangement allows a
certain quantity of sense current to continuously flow through the
electrode layer 130, way down to the tip thereof. The
magnetoresistive-effect device shown in FIG. 20 is more effective
than the magnetoresistive-effect device shown in FIG. 10 in the
prevention of the sense current from shunting into the insensitive
region, thereby in the control of the generation of noise.
[0434] If the magnetoresistive-effect devices shown in FIG. 1
through FIG. 14, having a tapered electrode layer toward its end,
are produced in accordance with the manufacturing method described
with reference to FIG. 15 through FIG. 19, it is difficult to form
the width dimension of the electrode layer extending over the
insensitive region at a constant width dimension. A
magnetoresistive-effect device having the end of the electrode
layer extending over into the sensitive region can result.
[0435] If the end of the electrode layer reaches the sensitive
region, the width dimension of the area of the electrode layer
permitting the sense current to flow therethrough becomes smaller
than the width dimension of the sensitive region, and the area of
the magnetoresistive-effect device capable of detecting the
magnetic field is thus narrowed.
[0436] In the magnetoresistive-effect device shown in FIG. 20, the
location of the insulator layer 131 on the multilayer film 200 is
accurately set using a manufacturing method to be described later
and the electrode layer 130 is prevented from extending beyond the
insensitive region.
[0437] Referring to FIG. 20, the width dimension T59 of the
electrode layer 130 extending over the insensitive region D of the
multilayer film 200 is preferably within a range from 0 .mu.m to
0.08 .mu.m. The width dimension T59 of the electrode layer 130 is
more preferably within a range of 0.05 .mu.m to 0.08 .mu.m.
[0438] By producing the magnetoresistive-effect device of FIG. 20
through the manufacturing method to be described later, the side
face of the multilayer film 200 and the side face of the insulator
layer 131 are set to be parallel to each other.
[0439] FIG. 21 is a cross-sectional view of the magnetoresistive
device of a sixteenth embodiment of the present invention, viewed
from an ABS side thereof.
[0440] The magnetoresistive-effect device shown in FIG. 21
includes, on a multilayer film 201 having the same construction as
the one in the magnetoresistive-effect device shown in FIG. 11, a
laminated insulator layer 133 constructed of Al.sub.2O.sub.3, and
electrode layers 132 and 132 with their end faces 130a and 130a in
direct contact with both sides of the insulator layer 133.
[0441] The construction and materials of the layers of the
multilayer film 201 remain the same as those of the
magnetoresistive-effect device shown in FIG. 11.
[0442] Metallic layers 88 and 88, hard bias layers 89 and 89 and
intermediate layers 90 and 90, coextending the width dimension T60
of the antiferromagnetic layer 80 extending in the X direction, are
identical, in construction and material, to the counterparts in the
magnetoresistive-effect device shown in FIG. 11.
[0443] The first pinned magnetic layer 81 and the second pinned
magnetic layer 83, having different magnetic moments, are in a
ferrimagnetic state with the magnetization directions thereof being
antiparallel. The first pinned magnetic layer 83 and the second
pinned magnetic layer 83 pin each other in magnetization direction,
thereby stabilizing the magnetization direction of the pinned
magnetic layer P in one direction as a whole.
[0444] In the magnetoresistive-effect device shown in FIG. 21, the
first free magnetic layer 85 and the second free magnetic layer 87,
having different magnetic moments and in a ferrimagnetic state with
magnetization directions thereof being antiparallel, are laminated
with the nonmagnetic material layer 86 interposed therebetween, and
function as a single free magnetic layer F.
[0445] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0446] In sixteenth embodiment again, the sensitive region E and
the insensitive regions D and D of the multilayer film 201 are
measured using the micro track profile method. Referring to FIG.
21, the portion, having the width dimension T61, of the multilayer
film 201 is the sensitive region E, and the portions, each having
the width dimension T62, on both sides of the sensitive region E
are the insensitive regions D and D.
[0447] In the sensitive region E, the magnetization direction of
the pinned magnetic layer P is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer P and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer P. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation.
[0448] The electrode layers 132 and 132 formed above the multilayer
film 201 extend over the multilayer film 201. The width dimension
of the top surface of the multilayer film 201 not covered with the
electrode layers 132 and 132 is the optical read track width
O-Tw.
[0449] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 132 and 132, is a width dimension T61, which is also the
dimension of the sensitive region E.
[0450] In the sixteenth embodiment, the electrode layers 132 and
132 formed on the multilayer film 201 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0451] It is not a requirement that the electrode layers 132 and
132 formed above the multilayer film 201 fully cover the
insensitive regions D and D, and the electrode layer 130 may be
narrower than the insensitive region D. In this case, the optical
read track width O-Tw becomes larger than the magnetic read track
width M-Tw.
[0452] The percentage of the sense current flowing from the
electrodes 132 and 132 to the multilayer film 201 without passing
through the hard bias layers 89 and 89 is increased.
[0453] The electrode layers 132 and 132 extending over the
insensitive regions D and D prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0454] As shown in FIG. 21, the protective layer 15 is formed where
the multilayer film 201 has no electrode layers 132 and 132
deposited thereon. The insulator layer 133 is deposited on the
protective layer 15. The electrode layers 132 and 132 are connected
to the second free magnetic layer 87 with no protective layer 15
interposed therebetween.
[0455] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 132 and 132 are
laminated on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0456] When the magnetoresistive-effect device shown in FIG. 21 is
produced using the manufacturing method to be described later, the
angle .theta.20 made between the end face 132a of the electrode
layer 132, extending over the insensitive region of the multilayer
film 201 and in contact with the insulator layer 133, and the top
surface 87a of the second free magnetic layer 87, is set to be 60
degrees or greater, or 90 degrees or greater. This arrangement
allows a certain quantity of sense current to continuously flow
through the electrode layer 132, way down to the tip thereof. The
magnetoresistive-effect device shown in FIG. 21 is more effective
than the magnetoresistive-effect device shown in FIG. 11 in the
prevention of the sense current from shunting into the insensitive
region, thereby in the control of the generation of noise.
[0457] In the magnetoresistive-effect device shown in FIG. 21, the
location of the insulator layer 133 on the multilayer film 201 is
accurately set using the manufacturing method to be described later
and the electrode layer 132 is prevented from extending beyond the
insensitive region and from narrowing the area of the
magnetoresistive-effect device capable of detecting the magnetic
field.
[0458] Referring to FIG. 21, the width dimension T63 of the
electrode layer 132 extending over the insensitive region D of the
multilayer film 201 is preferably within a range from 0 .mu.m to
0.08 .mu.m. The width dimension T63 of the electrode layer 132 is
more preferably within a range of 0.05 .mu.m to 0.08 .mu.m.
[0459] Referring to FIG. 21, the magnetic coupling junction M
between the multilayer film 201 and each of the hard bias layers 89
and 89 is fabricated of an interface with the end face of only the
first free magnetic layer 85, of both the first free magnetic layer
85 and the second free magnetic layer 87.
[0460] By producing the magnetoresistive-effect device of FIG. 21
through the manufacturing method to be described later, the side
face of the multilayer film 201 and the side face of the insulator
layer 133 are set to be parallel to each other.
[0461] FIG. 22 is a cross-sectional view of the magnetoresistive
device of a seventeenth embodiment of the present invention, viewed
from an ABS side thereof.
[0462] The magnetoresistive-effect device shown in FIG. 22
includes, on the multilayer film 202 having the same construction
as the one in the magnetoresistive-effect device shown in FIG. 12,
a laminated insulator layer 135 constructed of Al.sub.2O.sub.3, and
electrode layers 134 and 134 with their end faces 134a and 134a in
direct contact with both sides of the insulator layer 135.
[0463] The construction and materials of the layers of the
multilayer film 202 remain the same as those of the
magnetoresistive-effect device shown in FIG. 12. Referring to FIG.
22, however, no protective layer 15 is deposited on top of the
multilayer film 202.
[0464] The metallic layers 88 and 88, the hard bias layers 89 and
89 and the intermediate layers 90 and 90 deposited on the substrate
10 are identical, in construction and material, to the counterparts
in the magnetoresistive-effect device shown in FIG. 12.
[0465] The first pinned magnetic layer 81 and the second pinned
magnetic layer 83 are in a ferrimagnetic state with the
magnetization directions thereof being antiparallel. The first
pinned magnetic layer 81 and the second pinned magnetic layer 83
pin each other in magnetization direction, thereby stabilizing the
magnetization direction of the pinned magnetic layer P in one
direction as a whole.
[0466] In the magnetoresistive-effect device shown in FIG. 22, the
first free magnetic layer 85 and the second free magnetic layer 87,
having different magnetic moments and in a ferrimagnetic state with
the magnetization directions thereof being antiparallel, are
laminated with the nonmagnetic material layer 86 interposed
therebetween, and function as a single free magnetic layer F.
[0467] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0468] In the seventeenth embodiment again, the sensitive region E
and the insensitive regions D and D of the multilayer film 202 are
measured using the micro track profile method. Referring to FIG.
22, the portion, having the width dimension T64, of the multilayer
film 202 is the sensitive region E, and the portions, each having
the width dimension T65, on both sides of the sensitive region E
are the insensitive regions D and D.
[0469] In the sensitive region E, the magnetization direction of
the pinned magnetic layer P is pinned correctly in a direction
parallel to the Y direction, and the magnetization direction of the
free magnetic layer F is correctly aligned in the X direction. The
pinned magnetic layer P and the free magnetic layer F are thus
perpendicular in magnetization direction. The magnetization of the
free magnetic layer F varies sensitively in response to an external
magnetic field from the recording medium. An electrical resistance
varies in accordance with the relationship between the variation in
the magnetization direction of the free magnetic layer F and the
pinned magnetic field of the pinned magnetic layer P. A leakage
magnetic field from the recording medium is thus detected in
response to a variation in voltage due to the electrical resistance
variation.
[0470] The electrode layers 134 and 134 deposited above the
multilayer film 202 extend over the multilayer film 202. The width
dimension of the top surface of the multilayer film 202 not covered
with the electrode layers 134 and 134 is the optical read track
width O-Tw.
[0471] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 134 and 134, is a width dimension T64, which is also the
dimension of the sensitive region E.
[0472] In the seventeenth embodiment, the electrode layers 134 and
134 formed on the multilayer film 202 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0473] It is not a requirement that the electrode layers 134 and
134 formed above the multilayer film 202 fully cover the
insensitive regions D and D, and the electrode layer 134 may be
narrower than the insensitive region D. In this case, the optical
read track width O-Tw becomes larger than the magnetic read track
width M-Tw.
[0474] The percentage of the sense current flowing from the
electrodes 134 and 134 to the multilayer film 202 without passing
through the hard bias layers 89 and 89 is increased.
[0475] The electrode layers 134 and 134, extending over the
insensitive regions D and D, prevent the sense current from flowing
into the insensitive regions D and d, thereby controlling the
generation of noise.
[0476] Referring to FIG. 22, the protective layer 15 is not
deposited on top of the multilayer film 202, and the insulator
layer 135 is directly deposited on the antiferromagnetic layer 80.
The insulator layer 135 also serves as an antioxidizing protective
layer. The electrode layers 134 and 134 are directly in contact
with the antiferromagnetic layer 80.
[0477] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 134 and 134 are
deposited on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0478] When the magnetoresistive-effect device shown in FIG. 22 is
produced using the manufacturing method to be described later, the
angle .theta.22 made between the end face 134a of the electrode
layer 134, extending over the insensitive region of the multilayer
film 202 and in contact with the insulator layer 135, and the top
surface 80a of the antiferromagnetic layer 80, is set to be 60
degrees or greater, or 90 degrees or greater. This arrangement
allows a certain quantity of sense current to continuously flow
through the electrode layer 134, way down to the tip thereof. The
magnetoresistive-effect device shown in FIG. 22 is more effective
than the magnetoresistive-effect device shown in FIG. 12 in the
prevention of the sense current from shunting into the insensitive
region, thereby in the control of the generation of noise.
[0479] In the magnetoresistive-effect device shown in FIG. 22, the
location of the insulator layer 135 on the multilayer film 202 is
accurately set using the manufacturing method to be described later
and the electrode layer 134 is prevented from extending beyond the
insensitive region and from narrowing the area of the
magnetoresistive-effect device capable of detecting the magnetic
field.
[0480] Referring to FIG. 22, the width dimension T66 of the
electrode layer 134 extending over the insensitive region D of the
multilayer film 202 is preferably within a range from 0 .mu.m to
0.08 .mu.m. The width dimension T66 of the electrode layer 134 is
more preferably within a range of 0.05 .mu.m to 0.08 .mu.m.
[0481] Referring to FIG. 22, the magnetic coupling junction M
between the multilayer film 202 and each of the hard bias layers 89
and 89 is fabricated of an interface with the end face of only the
first free magnetic layer 87, of both the first free magnetic layer
85 and the second free magnetic layer 87.
[0482] By producing the magnetoresistive-effect device of FIG. 22
through the manufacturing method to be described later, the side
face of the multilayer film 202 and the side face of the insulator
layer 135 are set to be parallel to each other.
[0483] FIG. 23 is a cross-sectional view of the magnetoresistive
device of an eighteenth embodiment of the present invention, viewed
from an ABS side thereof.
[0484] The magnetoresistive-effect device shown in FIG. 23
includes, on the multilayer film 203 having the same construction
as the one in the magnetoresistive-effect device shown in FIG. 13,
a laminated insulator layer 137 constructed of Al.sub.2O.sub.3, and
electrode layers 136 and 136 with their end faces 136a and 136a in
direct contact with both sides of the insulator layer 137.
[0485] The construction and materials of the layers of the
multilayer film 203 remain the same as those of the
magnetoresistive-effect device shown in FIG. 13. Referring to FIG.
23, however, the layer 15 is deposited on top of the multilayer
film 203.
[0486] The metallic layers 113 and 113, the hard bias layers 114
and 114 and the intermediate layers 115 and 115 formed on the
substrate 10 are identical, coextending the width dimension T67 of
the antiferromagnetic layer 100 extending in the X direction, are
identical, in construction and material, to the counterparts in the
magnetoresistive-effect device shown in FIG. 13.
[0487] The first pinned magnetic layer 103 and the second pinned
magnetic layer 101 are in a ferrimagnetic state with the
magnetization directions thereof being antiparallel. The first
pinned magnetic layer 103 and the second pinned magnetic layer 101
pin each other in magnetization direction, thereby stabilizing the
magnetization direction of the pinned magnetic layer P.sub.1 in one
direction as a whole. The first pinned magnetic layer 103 and the
fourth pinned magnetic layer 111 are in a ferrimagnetic state with
the magnetization directions thereof being antiparallel.
[0488] In the magnetoresistive-effect device shown in FIG. 23, the
first free magnetic layer 105 and the second free magnetic layer
107, having different magnetic moments and in a ferrimagnetic state
with the magnetization directions thereof being antiparallel, are
laminated with the nonmagnetic material layer 106 interposed
therebetween, and function as a single free magnetic layer F.
[0489] The two end portions of the free magnetic layer F, having
disturbed magnetization directions, present a poor reproduction
gain, and become insensitive regions unable to exhibit no
substantial magnetoresistive effect.
[0490] In the eighteenth embodiment again, the sensitive region E
and the insensitive regions D and D of the multilayer film 203 are
measured using the micro track profile method. Referring to FIG.
23, the portion, having the width dimension T68, of the multilayer
film 203 is the sensitive region E, and the portions, each having
the width dimension T69, on both sides of the sensitive region E
are the insensitive regions D and D.
[0491] In the sensitive region E, the magnetization directions of
the pinned magnetic layers P.sub.1 and P.sub.2 are correctly
aligned in a direction parallel to the Y direction, and the
magnetization of the free magnetic layer F is correctly aligned in
the X direction. The pinned magnetic layers P.sub.1 and P.sub.2 and
the free magnetic layer F are perpendicular to each other in
magnetization direction. The magnetization of the free magnetic
layer F varies sensitively in response to an external magnetic
field from the recording medium. An electrical resistance varies in
accordance with the relationship between the variation in the
magnetization direction of the free magnetic layer F and the pinned
magnetic field of the pinned magnetic layers P.sub.1 and P.sub.2. A
leakage magnetic field from the recording medium is thus detected
in response to a variation in voltage due to the electrical
resistance variation.
[0492] The electrode layers 136 and 136 formed above the multilayer
film 203 extend over the multilayer film 203. The width dimension
of the top surface of the multilayer film 203 not covered with the
electrode layers 134 and 134 is the optical read track width
O-Tw.
[0493] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 136 and 136, is the width dimension T68, which is also the
dimension of the sensitive region E.
[0494] In the eighteenth embodiment, the electrode layers 136 and
136 formed on the multilayer film 203 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0495] It is not a requirement that the electrode layers 136 and
136 formed above the multilayer film 203 fully cover the
insensitive regions D and D, and the electrode layer 136 may be
narrower than the insensitive region D. In this case, the optical
read track width O-Tw becomes larger than the magnetic read track
width M-Tw.
[0496] The percentage of the sense current flowing from the
electrodes 136 and 136 to the multilayer film 203 without passing
through the hard bias layers 114 is increased.
[0497] The electrode layers 136 and 136, extending over the
insensitive regions D and D, prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0498] Referring to FIG. 23, the protective layer 15 is not
deposited on top of the multilayer film 203, and the insulator
layer 137 is directly deposited on the antiferromagnetic layer 112.
The insulator layer 137 also serves as an antioxidizing protective
layer. The electrode layers 136 and 136 are directly in contact
with the antiferromagnetic layer 112.
[0499] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 136 and 136 are
deposited on the protective layer 15, improving the characteristics
of the magnetoresistive-effect device.
[0500] When the magnetoresistive-effect device shown in FIG. 23 is
produced using the manufacturing method to be described later, the
angle .theta.23 made between the end face 136a of the electrode
layer 136, extending over the insensitive region of the multilayer
film 203 and in contact with the insulator layer 137, and the top
surface 112a of the antiferromagnetic layer 112, is set to be 60
degrees or greater, or 90 degrees or greater. This arrangement
allows a certain quantity of sense current to continuously flow
through the electrode layer 136, way down to the tip thereof. The
magnetoresistive-effect device shown in FIG. 23 is more effective
than the magnetoresistive-effect device shown in FIG. 13 in the
prevention of the sense current from shunting into the insensitive
region, thereby in the control of the generation of noise.
[0501] In the magnetoresistive-effect device shown in FIG. 23, the
location of the insulator layer 137 on the multilayer film 203 is
accurately set using the manufacturing method to be described later
and the electrode layer 136 is prevented from extending beyond the
insensitive region and from narrowing the area of the
magnetoresistive-effect device capable of detecting the magnetic
field.
[0502] Referring to FIG. 23, the width dimension T70 of the
electrode layer 136 extending over the insensitive region D of the
multilayer film 203 is preferably within a range from 0 .mu.m to
0.08 .mu.m. The width dimension T70 of the electrode layer 136 is
more preferably within a range of 0.05 .mu.m to 0.08 .mu.m.
[0503] Referring to FIG. 23, the magnetic coupling junction M
between the multilayer film 203 and each of the hard bias layers
114 and 114 is fabricated of an interface with the end face of only
the first free magnetic layer 105, of both the first free magnetic
layer 105 and the second free magnetic layer 107.
[0504] By producing the magnetoresistive-effect device of FIG. 23
through the manufacturing method to be described later, the side
face of the multilayer film 203 and the side face of the insulator
layer 137 are set to be parallel to each other.
[0505] FIG. 24 is a cross-sectional view of the magnetoresistive
device of a nineteenth embodiment of the present invention, viewed
from an ABS side thereof.
[0506] The magnetoresistive-effect device shown in FIG. 24
includes, on the multilayer film 61 having the same construction as
the one in the magnetoresistive-effect device shown in FIG. 14, a
laminated insulator layer 141 constructed of Al.sub.2O.sub.3, and
electrode layers 140 and 140 with their end faces 140a and 140a in
direct contact with both sides of the insulator layer 141.
[0507] The construction and materials of the layers of the
multilayer film 61 remain the same as those of the
magnetoresistive-effect device shown in FIG. 14. Referring to FIG.
24, however, the layer 55 is not deposited on top of the multilayer
film 61.
[0508] The hard bias layers 56 and 56 and the intermediate layers
57 and 57 are identical, in construction and material, to the
counterparts in the magnetoresistive-effect device shown in FIG.
14.
[0509] In the nineteenth embodiment again, the sensitive region E
and the insensitive regions D and D of the multilayer film 61 are
measured using the micro track profile method. Referring to FIG.
24, the portion, having the width dimension T19, of the multilayer
film 61 is the sensitive region E, and the portions, each having
the width dimension T20, on both sides of the sensitive region E
are the insensitive regions D and D.
[0510] The electrode layers 140 and 140 formed on both sides of the
multilayer film 61 extend over the multilayer film 61. The width
dimension of the top surface of the multilayer film 61 not covered
with the electrode layers 140 and 140 is the optical read track
width O-Tw.
[0511] The magnetic read track width M-Tw, determined by the width
dimension of the sensitive region E not covered with the electrode
layers 140 and 140, is the width dimension T19, which is also the
dimension of the sensitive region E.
[0512] In the nineteenth embodiment, the electrode layers 140 and
140 formed on the multilayer film 61 fully cover the insensitive
regions D and D, setting the optical read track width O-Tw and the
magnetic read track width M-Tw (i.e., the width dimension of the
sensitive region E) to approximately the same dimension.
[0513] It is not a requirement that the electrode layers 140 and
140 formed above the multilayer film 203 fully cover the
insensitive regions D and D, and the electrode layer 140 may be
narrower than the insensitive region D. In this case, the optical
read track width O-Tw becomes larger than the magnetic read track
width M-Tw.
[0514] The percentage of the sense current flowing from the
electrodes 140 and 140 to the multilayer film 61 without passing
through the hard bias layers 56 and 56 is increased in this
embodiment.
[0515] The electrode layers 140 and 140 extending over the
insensitive regions D and D prevent the sense current from flowing
into the insensitive regions D and D, thereby controlling the
generation of noise.
[0516] Referring to FIG. 24, the protective layer 55 is not
deposited on top of the multilayer film 61, and the insulator layer
141 is directly deposited on the magnetoresistive layer 54. The
insulator layer 141 also serves as an antioxidizing protective
layer. The electrode layers 140 and 140 are directly in contact
with the magnetoresistive layer 54.
[0517] This arrangement presents a smaller electrical resistance
than the arrangement in which the electrode layers 140 and 140 are
deposited on the protective layer 55, improving the characteristics
of the magnetoresistive-effect device.
[0518] When the magnetoresistive-effect device shown in FIG. 24 is
produced using the manufacturing method to be described later, the
angle .theta.24 made between the end face 140a of the electrode
layer 140, extending over the insensitive region of the multilayer
film 61 and in contact with the insulator layer 141, and the top
surface 54a of the magnetoresistive layer 54, is set to be 60
degrees or greater, or 90 degrees or greater. This arrangement
allows a certain quantity of sense current to continuously flow
through the electrode layer 140, way down to the tip thereof. The
magnetoresistive-effect device shown in FIG. 24 is more effective
than the magnetoresistive-effect device shown in FIG. 14 in the
prevention of the sense current from shunting into the insensitive
region, thereby in the control of the generation of noise.
[0519] In the magnetoresistive-effect device shown in FIG. 24, the
location of the insulator layer 141 on the multilayer film 61 is
accurately set using the manufacturing method to be described later
and the electrode layer 140 is prevented from extending beyond the
insensitive region and from narrowing the area of the
magnetoresistive-effect device capable of detecting the magnetic
field.
[0520] Referring to FIG. 24, the width dimension T71 of the
electrode layer 141 extending over the insensitive region D of the
multilayer film 61 is preferably within a range from 0 .mu.m to
0.08 .mu.m. The width dimension T71 of the electrode layer 140 is
more preferably within a range of 0.05 .mu.m to 0.08 .mu.m.
[0521] In the AMR device, the hard bias layers 56 and 56 are
magnetized in the X direction as shown, and the magnetoresistive
layer 54 is supplied with the bias magnetic field in the X
direction by the hard bias layers 56 and 56. Furthermore, the
magnetoresistive layer 54 is supplied with the bias field in the Y
direction by the soft magnetic layer 52. With the magnetoresistive
layer 54 supplied with the bias magnetic fields in the X direction
and Y direction, a variation in magnetization thereof in response
to a variation in the magnetic field becomes linear.
[0522] The sense current from the electrode layers 140 and 140 is
directly fed to the magnetoresistive layer 54 in the sensitive
region E. The direction of the advance of the recording medium is
aligned with the Z direction. When a leakage magnetic field from
the recording medium in the Y direction is applied, the
magnetization direction of the magnetoresistive layer 54 varies,
causing a variation in the resistance. The resistance variation is
then detected as a voltage variation.
[0523] By producing the magnetoresistive-effect device of FIG. 24
through the manufacturing method to be described later, the side
face of the multilayer film 61 and the side face of the insulator
layer 141 are set to be parallel to each other.
[0524] The formation of the insulator layer between the electrode
layers makes mild the inclination of the top surface of each of the
magnetoresistive-effect devices as shown in FIG. 20 through FIG.
24. Even if the angle made between the top surface of the
protective layer, the free magnetic layer or the antiferromagnetic
layer and the end face of each electrode layer becomes large, a
short is less likely to occur between the electrode layers and a
top shield layer of a soft magnetic material when the top shield
layer is deposited over the multilayer film and the electrode
layers.
[0525] The manufacturing method for manufacturing the
magnetoresistive-effect devices shown in FIGS. 20 through 24 is now
discussed, referring to drawings.
[0526] Referring to FIG. 25, a multilayer film 151 of the
magnetoresistive-effect device is formed on a substrate 150. An
insulator layer 152, made of Al.sub.2O.sub.3, is formed on the
multilayer film 151. The multilayer film 151 can be any of the
multilayer films of the single spin-valve type thin-film devices
shown in FIG. 20 through FIG. 22, the multilayer film of the dual
spin-valve type thin-film devices shown in FIG. 23, and the
multilayer film of the AMR device shown in FIG. 24.
[0527] To form the antiferromagnetic layer 70, 80, or 100 in the
extended form thereof in the X direction respectively shown in FIG.
20, FIG. 21, or FIG. 23, an etch rate and etch time are controlled
to leave the side portions of the antiferromagnetic layer 70, 80,
or 100 when the side portions of the multilayer film 151 and the
insulator layer 152, shown in FIG. 26, are etched away.
[0528] When the multilayer film 151 is a multilayer film for a
single spin-valve type thin-film device or a dual spin-valve type
thin-film device, the antiferromagnetic layer in the multilayer
film 151 is preferably made of a PtMn alloy, or may be made of an
X--Mn alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, and alloys thereof, or a Pt--Mn--X'
alloy where X' is a material selected from the group consisting of
Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof. When the
antiferromagnetic layer is made of one of the above-cited
materials, the antiferromagnetic layer needs to be subjected to a
heat treatment to generate an exchange coupling magnetic field in
the interface with the pinned magnetic layer.
[0529] FIG. 33 shows a conventional magnetoresistive-effect device
having its hard bias layers and electrode layers on only both sides
of the multilayer film. The width dimension A of the top surface of
the multilayer film of the conventional magnetoresistive-effect
device is measured using an optical microscope as shown in FIG. 31.
The magnetoresistive-effect device is then scanned across a micro
track having a signal recorded thereon, on a recording medium in
the direction of the track width, and a reproduction output is
detected. A top width dimension of B giving an output equal to or
greater than 50% of a maximum reproduction output is defined as the
sensitive region E and a top width dimension of C giving an output
smaller than 50% of the maximum reproduction output is defined as
the insensitive region D.
[0530] Based on these measurement results, a lift-off resist layer
153 is deposited on the multilayer film 151, paying attention to
the width dimension C of the insensitive regions D and D measured
through the micro track profile method.
[0531] Referring to FIG. 25, undercuts 153a and 153a are formed on
the underside of the resist layer 153. The resist layer 153 serves
as a mask for etching the insulator layer 152 in a later step. The
resist layer 153 is adjusted to grow so that the bottom face of the
insulator layer 152 fully covers the sensitive region E of the
multilayer film 151 after the etching of the insulator layer 152.
The undercuts 153a and 153a are chiefly formed above the
insensitive regions D and D of the multilayer film 151. When the
side walls of the resist layer 153 are inclined at an angle
subsequent to the etching, the undercuts 153a and 153a may cut into
the area above the sensitive region E by a slight depth to account
for the inclined wall face.
[0532] In a manufacturing step shown in FIG. 26, both sides of each
of the multilayer film 151 and the insulator layer 152 are etched
away.
[0533] In a manufacturing step shown in FIG. 27, the insensitive
regions D and D of the multilayer film 151 are exposed by etching
away only the insulator layer 152 of Al.sub.2O.sub.3 in a alkaline
solution. The layers forming the multilayer film 151 are not
dissolved into the alkaline solution. In the state shown in FIG.
27, the bottom face of the insulator layer 152 fully covers the
sensitive region E of the multilayer film 151.
[0534] When the insulator layer 152 of Al.sub.2O.sub.3 is etched in
the alkaline solution, the side walls of the insulator layer 152
are respectively maintained parallel to the side walls of the
multilayer film 151, and even after the etching process, the side
walls of the insulator layer 152 and the side walls of the
multilayer film 151 are maintained parallel to each other.
[0535] When the magnetoresistive-effect devices shown in FIG. 21 is
manufactured, the protective layer is deposited on top of the
multilayer film 151, and the insulator layer 152 and the resist
layer 153 are successively formed on top of the protective layer.
Subsequent to the manufacturing step shown in FIG. 27, the portions
of the protective layer, which come just below the undercuts 153a
and 153a of the resist layer 153, namely, the portions not covered
with the insulator layer 152, are removed through an obliquely
entering ion milling beam to expose the layer beneath the
protective layer.
[0536] In a manufacturing step shown in FIG. 28, hard bias layers
154 and 154 are deposited on both sides of the multilayer film 151.
In this invention, the sputtering technique, used to form the hard
bias layers 154 and 154 and electrode layers 156 and 156 to be
formed subsequent to the formation of the hard bias layers 154 and
154, is preferably at least one sputtering technique selected from
an ion-beam sputtering method, a long-throw sputtering method, and
a collimation sputtering method.
[0537] In accordance with the present invention, as shown in FIG.
28, a substrate 150 having the multilayer film 151 formed thereon
is placed normal to a target 155 having the same composition as
that of the hard bias layers 154 and 154. In this setup, the hard
bias layers 154 and 154 are grown in a direction normal to the
multilayer film 151 using the ion-beam sputtering method, for
instance. Less sputter particles are deposited in the regions of
the hard bias layers 154 and 154 in contact with the multilayer
film 151, because of the overhang by both end portions of the
resist layer 153. The thickness of the hard bias layers 154 and 154
is thinner in the regions thereof in contact with the multilayer
film 151, and the top surface of the hard bias layers 154 and 154
are downwardly inclined or curved toward the multilayer film 151 as
shown. Referring to FIG. 28, a layer 154a having the same
composition as that of the hard bias layers 154 and 154 is
deposited on top of the resist layer 153.
[0538] In the manufacturing step shown in FIG. 28, the hard bias
layers 154 and 154 are preferably formed so that the height
position of the top edge or the bottom edge (in the Z direction) of
the magnetic coupling junction between the multilayer film 151 and
each of the hard bias layers 154 and 154 is at the same level as
the height position of the top surface or the bottom surface of the
free magnetic layer or the magnetoresistive-effect layer in the
direction of the advance of the recording medium.
[0539] It is sufficient if each of the hard bias layers 154 and 154
is magnetically coupled with the free magnetic layer only or the
magnetoresistive-effect layer only. The influence of the magnetic
field generated from the bias layers 154 and 154 on the
magnetization direction of the pinned magnetic layer is controlled,
if the hard bias layers 154 and 154 remain magnetically uncoupled
with the pinned magnetic layer.
[0540] If the multilayer film 151 includes a free magnetic layer
which is composed of a plurality of soft magnetic thin-film layers
having different magnetic moments and separated from each other by
nonmagnetic material layers, like the multilayer film of one of the
thin-film devices shown in FIG. 20 through FIG. 23, the hard bias
layers 154 and 154 are preferably formed so that the magnetic
coupling junction between the multilayer film 151 and each of the
hard bias layers 154 and 154 is fabricated of an interface with the
end face of only one of the plurality of the soft magnetic thin
films forming the free magnetic layer.
[0541] If the magnetic coupling junction between the multilayer
film 151 and each of the hard bias layers 154 and 154 is fabricated
of an interface with the end face of only one of the plurality of
the soft magnetic thin-film layers forming the free magnetic layer,
the magnetization direction of the soft magnetic thin-film layer on
both end portions is free from disturbance.
[0542] In a manufacturing step shown in FIG. 29, the electrode
layers 156 and 156 are obliquely grown on the hard bias layers 154
and 154 at an angle to the multilayer film 151. In this case, the
electrode layers 156 and 156 are grown into the undercuts 153a and
154a formed on the underside of the resist layer 153 arranged on
top of the multilayer film 151.
[0543] Referring to FIG. 29, the target 157 having the same
composition as that of the electrode layer 156 is inclined at an
angle to the substrate 150 having the multilayer film 151 formed
thereon, and the electrode layers 156 and 156 are grown on the hard
bias layers 154 and 154 using the ion-beam sputtering method while
moving the target 157 transversely across the substrate 150. The
electrode layers 156 and 156 sputtered at an angle to the
multilayer film 151 are formed not only on the hard bias layers 154
and 154 but also into the undercuts 153a and 153a of the resist
layer 153.
[0544] Specifically, the electrode layers 156 and 156 formed within
the undercuts 153a and 153a are grown on the insensitive regions D
and D of the multilayer film 151.
[0545] The end face 156b of each of the electrode layers 156 and
156 is in contact with both side walls of the insulator layer
152.
[0546] Referring to FIG. 29, the target 157 is moved at an angle
with respect to a fixed substrate 150. Alternatively, the substrate
150 is moved at an angle with respect to a fixed target 157. As
shown in FIG. 29, a layer 156a having the same composition as that
of the electrode layers 156 and 156 is formed on top of the layer
154a on the resist layer 154.
[0547] When the portions of the protective layer, formed on top of
the multilayer film 151, are removed to expose the underlayer
beneath the protective layer, the electrode layers 156 and 156 are
formed on the free magnetic layer beneath the protective layer as
in the magnetoresistive-effect device shown in FIG. 21.
[0548] In a manufacturing step shown in FIG. 30, the resist layer
153 shown in FIG. 29 is removed through a lift-off process, and
this completes a magnetoresistive-effect device having the
electrode layers 156 and 156 formed on top of the insensitive
regions D and D of the multilayer film 151 and the insulator layer
152 formed between the electrode layers 156 and 156.
[0549] In the film forming process of the electrode layers 156 and
156, the angle .theta. made between the end face 156b of the
electrode layer 156 extending over the insensitive region D and in
contact with the side walls of the insulator layer 152 and the top
surface 151a of the multilayer film 151 is preferably 60 degrees or
greater, and more preferably 90 degrees or greater. This
arrangement allows a certain quantity of sense current to
continuously flow through the electrode layer 156, way down to the
tip thereof. The magnetoresistive-effect device manufactured in
this way is more effective than the magnetoresistive-effect devices
shown in FIG. 1 through FIG. 14 in the prevention of the sense
current from shunting into the insensitive region, thereby in the
control of the generation of noise.
[0550] Since the location of the insulator layer 152 on the
multilayer film 151 is accurately set, the electrode layers 156 and
156 are prevented from extending beyond the insensitive region and
from narrowing the area of the magnetoresistive-effect device
capable of detecting the magnetic field.
[0551] Tests have been conducted to measure the relationship of the
width dimension of each electrode, formed to extend over the
multilayer film constituting the magnetoresistive-effect device,
with the direct current resistance (DCR) and the noise generation
rate.
[0552] The magnetoresistive-effect device tested in measurements is
a spin-valve type thin-film device shown in FIG. 5. The width
dimension of the top surface of the multilayer film in the
magnetoresistive-effect device is 1.4 .mu.m.
[0553] The electrode layers formed on both sides and above the
multilayer film extend over the multilayer film. The width
dimension of the electrode layer extending over the multilayer film
is increased from 0 .mu.m to 0.12 .mu.m in steps of 0.01 .mu.m to
produce a plurality of magnetoresistive-effect devices. In each of
the magnetoresistive-effect devices, the relationship of the width
dimension of each electrode, formed to extend over the multilayer
film, with the direct current resistance (DCR) and the noise
generation rate, is measured. The test results are plotted in FIG.
32.
[0554] FIG. 32 shows that the larger the width dimension of the
electrode layer extending over the multilayer, the smaller the
direct current resistance. When the electrode layer is formed on
the multilayer film with its width dimension enlarged, the
electrode layer covers the insensitive region D in the side end
portion of the multilayer film, and the sense current from the
electrode layer is effectively conducted to the sensitive region E.
As the junction area of the electrode layer with the multilayer
film is increased, the direct current resistance is reduced.
[0555] As shown in FIG. 32, when the width dimension of the
electrode layer extending over the multilayer film is 0.08 .mu.m,
the direct current resistance is smaller than the one with no
electrode layer formed at all on the multilayer film (i.e., the
direct current resistance at an electrode layer width dimension of
0 .mu.m) and no noise is generated in the reproduction output.
[0556] It is found that an excessively large width dimension of the
electrode layer formed on the multilayer film generates noise in
the reproduction output.
[0557] The noise generation rate rises as shown in FIG. 32, when
the width dimension of the electrode layer formed on the multilayer
film increases above 0.08 .mu.m. This is because the area of the
multilayer film as wide as 0.08 .mu.m from its edge is the
insensitive region D. If the electrode layer extends beyond the
0.08 .mu.m area, the electrode layer extends into the sensitive
region E. Although the sensitive region E exhibits effectively the
magnetoresistive effect, a portion of the sensitive region E having
the electrode layer deposited thereon falls outside the magnetic
read track width M-Tw, and the output produced therein becomes
noise. The test results show that the electrode layer extending
over the multilayer film preferably extends over the insensitive
region D but not into the sensitive region E beyond the insensitive
region D.
[0558] From the above discussion, the width dimension of the
electrode layers on both sides of the multilayer film is preferably
within a range from 0 .mu.m to 0.08 .mu.m.
[0559] In accordance with the present invention, the electrode
layers, above and on both sides of the multilayer film, are formed
to extend over the insensitive regions, on both side portions of
the multilayer film, having a poor magnetoresistive effect without
reproduction capability. This arrangement makes it easier for the
sense current to flow into the multilayer film from the electrode
layers without passing through the hard bias layers. The junction
area between the electrode layers and the multilayer film thus
increases, reducing the direct current resistance, and thereby
improving the reproduction characteristics.
[0560] In accordance with the present invention, the electrode
layers are formed to reliably and easily extend over the
insensitive regions of the multilayer film with the lift-off resist
employed, using the ion-beam sputtering method.
[0561] FIG. 35 is a cross-sectional view showing the construction
of the magnetoresistive-effect device of a twentieth embodiment of
the present invention, viewed from an ABS side thereof. FIG. 35
shows only the central portion of the device sectioned in an XZ
plane.
[0562] The magnetoresistive-effect device is a spin-valve type
thin-film device, namely, one type of GMR (giant magnetoresistive)
devices making use of the giant magnetoresistive effect. The
spin-valve type thin-film device is mounted on the trailing end of
a floating slider in a hard disk device to detect a magnetic field
recorded onto a hard disk. The direction of the movement of a
magnetic recording medium such as a hard disk is aligned with the Z
direction, and the direction of a leakage magnetic field of the
magnetic recording medium is aligned with the Y direction.
[0563] A substrate 319, fabricated of a nonmagnetic material such
as Ta (tantalum), becomes the bottom layer of the device as shown
in FIG. 35. An antiferromagnetic layer 320, a pinned magnetic layer
312, a nonmagnetic electrically conductive layer 313, and a free
magnetic layer 314 are laminated onto the substrate 319. A
protective layer 315, fabricated of Ta (tantalum), is formed on the
free magnetic layer 314. A multilayer film 316 thus includes the
substrate 319 through the protective layer 315. Referring to FIG.
35, the width dimension of the top surface of the multilayer film
316 is T30.
[0564] The pinned magnetic layer 312 is deposited on and in direct
contact with the antiferromagnetic layer 320, and is subjected to
annealing in the presence of a magnetic field. An exchange
anisotropic magnetic field takes place through exchange coupling at
the interface between the antiferromagnetic layer 320 and the
pinned magnetic layer 312. The magnetization of the pinned magnetic
layer 312 is thus pinned in the Y direction.
[0565] In accordance with the present invention, the
antiferromagnetic layer 320 is made of a Pt--Mn
(platinum-manganese) alloy film. The Pt--Mn alloy film outperforms
an Fe--Mn alloy film and Ni--Mn alloy film, conventionally used as
an antiferromagnetic layer, in terms of corrosion resistance, and
has a high blocking temperature, and further provides a large
exchange anisotropic magnetic field (Hex). The Pt--Mn alloy film
has thus excellent characteristics as an antiferromagnetic
material.
[0566] Instead of the Pt--Mn alloy, the antiferromagnetic layer 320
may be made of an X--Mn alloy where X' is a material selected from
the group consisting of Pd, Ir, Rh, Ru, and alloys thereof, or a
Pt--Mn--X' alloy where X' is a material selected from the group
consisting of Pd, Ir, Rh, Ru, Au, Ag, and alloys thereof.
[0567] The pinned magnetic layer 312 and the free magnetic layer
314 are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt), an
Fe--Co (iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the
nonmagnetic electrically conductive layer 313 is made of a low
electrical-resistance nonmagnetic electrically conductive material,
such as Cu (copper).
[0568] Referring to FIG. 35, hard bias layers 317 and 317 are
formed on both sides of the multilayer film 316, composed of the
substrate 319 through the protective layer 315. The hard bias
layers 317 and 317 are made of a Co--Pt (cobalt-platinum) alloy or
a Co--Cr--Pt (cobalt-chromium-platinum) alloy.
[0569] The hard bias layers 317 and 317 are magnetized in the X
direction (i.e., the direction of a track width), and the
magnetization of the free magnetic layer 314 is aligned in the X
direction under the bias magnetic field in the X direction from the
hard bias layers 317 and 317.
[0570] Intermediate layers 321 and 321, made of a high-resistivity
material having a resistance higher than that of the electrode
layers 318 and 318 or an insulating material, or a laminate of a
high-resistivity material and an insulating material, are separated
from the hard bias layers 317 and 317 by antimagnetic layers 323
and 323. When an oxide or Si compound is used for the intermediate
layer 321, the antimagnetic layer 323 is preferably interposed
between each of the hard bias layers 317 and 317 and each of the
electrode layers 318 and 318. Without the antimagnetic layer 323,
diffusion is likely to take place between the hard bias layers 317
and 317, made of CoPt, and the intermediate layers 321 and 321 made
of the oxide or Si compound. When the intermediate layers 321 and
321 are constructed of an N compound, however, such a diffusion is
less likely to take place, and the antimagnetic layer 323 is
dispensed with.
[0571] The high-resistivity material 321, which fabricates the
intermediate layer 321, is preferably at least one material
selected from the group consisting of TaSiO.sub.2, TaSi,
CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and TaN.
[0572] Furthermore, the high-resistivity material, which fabricates
the intermediate layer 321, is preferably at least one material
selected from the group consisting of Al.sub.2O.sub.3, SiO.sub.2,
Ti.sub.2O.sub.3, TiO, WO, AlN, Si.sub.3N.sub.4, B.sub.4C, SiC, and
SiAlON.
[0573] Referring to FIG. 35, the electrode layers 318 and 318 are
deposited on nonmagnetic materials 234 and 324, made of Ta, which
are respectively deposited on top of the intermediate layers 321
and 321. In the twentieth embodiment, the electrode layers 318 and
318 are formed to extend over the multilayer film 316. When an
oxide or Si compound is used for the intermediate layers 321 and
321, the use of the nonmagnetic material 234 and 324 is preferable.
When an N compound is used for the intermediate layers 321 and 321,
whether to use the nonmagnetic material 234 and 324 is not
important.
[0574] Since the electrode layers 318 and 318 are formed to extend
over the multilayer film 316, the electrode layers 318 and 318 are
connected to each other through the multilayer film 316. The
electrode layers 318 and 318 are made of Ta (tantalum) or Cr
(chromium).
[0575] Since the intermediate layers 321 and 321, made of at least
one of a high-resistivity material having a resistance higher than
that of the electrode layers 318 and 318 and an insulating
material, are interposed between each of the hard bias layers 317
and 317 and each of the electrode layers 318 and 318, the sense
current from the electrode layer 318 is less likely to flow into
the hard bias layer 17. The percentage of the sense current
shunting into the hard bias layer 317 is thus reduced.
[0576] In accordance with the present invention, the electrode
layers 318 and 318 are formed to extend over the multilayer film
316, and the sense current directly flows from the electrode layer
318 formed on the multilayer film 316 into the multilayer film 316
without passing through the hard bias layer 317, because of the
presence of the intermediate layers 321 and 321. The
magnetoresistive-effect device of this invention thus enhances the
reproduction gain, thereby resulting in high reproduction output,
compared with the conventional magnetoresistive-effect devices.
[0577] One of the reasons for the increase in the reproduction
output is that the sense current flows with ease from the electrode
layer 318 into chiefly the nonmagnetic electrically conductive
layer 313 of the multilayer film 316, leading to a large
magnetoresistive effect.
[0578] The magnetoresistive effect is exhibited by the three layers
of the pinned magnetic layer 312, the nonmagnetic electrically
conductive layer 313, and the free magnetic layer 314. The
magnetization direction of the pinned magnetic layer 312 is pinned
in the Y direction, and the magnetization of the free magnetic
layer 314, aligned in the direction of the track width (i.e., the X
direction), freely varies in response to the external magnetic
field. When the magnetization of the free magnetic layer 314 varies
in response to the external magnetic field, the sense current flows
into the nonmagnetic electrically conductive layer 313. When
electrons move from one of the free magnetic layer 314 and the
pinned magnetic layer 312 to the other, the electrons scatter in
the interface between the nonmagnetic electrically conductive layer
313 and the pinned magnetic layer 312 or in the interface between
the nonmagnetic electrically conductive layer 313 and the free
magnetic layer 314, causing the electrical resistance to vary. A
voltage change in response to the electrical resistance variation
gives rise to a reproduction output.
[0579] As shown in FIG. 35, in accordance with the present
invention, the electrode layers 318 and 318 are formed to extend
over the multilayer film 316 so that the sense current directly
flows from the electrode layer 318 into the multilayer film 316.
The sense current also flows into the free magnetic layer 314 on
top of the nonmagnetic electrically conductive layer 313 of the
multilayer film 316, although the sense current chiefly flows into
the nonmagnetic electrically conductive layer 313 with ease.
[0580] In contrast, the conventional magnetoresistive-effect device
shown in FIG. 33 is designed so that the sense current flows from
the electrode layer 8 via the hard bias layer 5 to the multilayer
film 9 from its side face (in the X direction). With this
arrangement, the sense current shunts to not only the nonmagnetic
electrically conductive layer 3 but also the antiferromagnetic
layer 1, the pinned magnetic layer 2 and the free magnetic layer 4.
The quantity of the sense current flowing into the nonmagnetic
conductive layer 3 is reduced.
[0581] Compared with the construction of the conventional
magnetoresistive-effect device, the construction of the
magnetoresistive-effect device in this embodiment allows the sense
current to substantially flow into the nonmagnetic electrically
conductive layer 313. A large magnetoresistive effect results,
improving the reproduction output.
[0582] With the pinned magnetic layer 312 employed, the sense
current is less likely to shunt into the hard bias layer 317 from
the electrode layer 318 even if the thickness h2 of the electrode
layer 318 formed in contact with the multilayer film 316 is made
thinner. This arrangement allows the sense current to directly flow
into the multilayer film 316 from the electrode layer 318.
[0583] The use of the thin electrode layer 318, having a thickness
of h2, formed in contact with the multilayer film 316 reduces the
size of a step between the top surface of the electrode layer 318
and the top surface of the multilayer film 316. This arrangement
allows an upper gap layer 379 to be formed over the border area
between the electrode layer 318 and the multilayer film 316 with an
improved step coverage and with no film discontinuity involved, and
provides sufficient insulation.
[0584] However, there is a limitation on the extension of the
electrode layer 318 over the multilayer film 316. Referring to FIG.
35, the portion, having the width dimension T2, in the center of
the multilayer film 316 is the sensitive region E, while the
portions, each having the width dimension T1, on both sides of the
sensitive region E are the insensitive regions D and D.
[0585] In the sensitive region E, the magnetization of the pinned
magnetic layer 312 is correctly pinned in the Y direction as shown.
Since the magnetization of the free magnetic layer 314 is correctly
aligned in the X direction, the magnetization of the pinned
magnetic layer 312 is perpendicular to the magnetization of the
free magnetic layer 314. The magnetization of the free magnetic
layer 314 in the sensitive region E varies sensitively in response
to an external magnetic field from the recording medium. In other
words, the sensitive region E is a portion that substantially
exhibits the magnetoresistive effect.
[0586] In contrast, in the insensitive regions D and D arranged on
both sides of the sensitive region E, the magnetizations of pinned
magnetic layer 312 and the free magnetic layer 314 are greatly
affected by the hard bias layers 317 and 317, and the magnetization
of the free magnetic layer 314 is less susceptible to the external
magnetic field. In other words, the insensitive regions D and D
provide a weak magnetoresistive effect with a reproduction
capability thereof reduced.
[0587] In the twentieth embodiment of the present invention, the
width dimension T2 of the sensitive region E, and the width
dimension of the insensitive region D of the multilayer film 316
are measured through the previously discussed micro track profile
method (see FIG. 31).
[0588] Referring to FIG. 35, in this embodiment of the present
invention, the electrode layers 318 and 318 directly formed on the
hard bias layers 317 and 317 on both sides of the multilayer film
316 are formed to extend over the insensitive region D of the
multilayer film 316 by a width dimension of T3. The width dimension
of the top surface of the multilayer film 316 not covered with the
electrode layers 318 and 318 is defined as an optical read track
width O-Tw measured through an optical method.
[0589] The width dimension T2 of the sensitive region E not covered
with the electrode layers 318 and 318 substantially functions as a
track width, and this width dimension is defined as a magnetic read
track width M-Tw.
[0590] In the twentieth embodiment shown in FIG. 35, the optical
read track width O-Tw, the magnetic read track width M-Tw, and the
width dimension T2 of the sensitive region E substantially have the
same dimension.
[0591] In the twentieth embodiment of the present invention, the
electrode layer 318 overlaps the insensitive regions D and D of the
multilayer film 316. The sense current is more likely to dominantly
flow from the electrode layer 318 into the sensitive region E that
substantially exhibits the magnetoresistive effect, rather than
flowing into the insensitive regions D and D. The reproduction
output is even more increased.
[0592] Particularly when the optical read track width O-Tw and the
width dimension T2 (i.e., the magnetic read track width M-Tw) of
the sensitive region E are set to be approximately the same
dimension, the sense current more easily flows into the sensitive
region E, thereby further improving the reproduction
characteristics.
[0593] Although the electrode layers 318 and 318 fully cover the
insensitive regions D and D in the twentieth embodiment shown in
FIG. 35, it is not a requirement that the electrode layers 318 and
318 fully cover the insensitive regions D and D. The insensitive
regions D and D may be partly exposed. In this case, the optical
read track width O-Tw becomes larger than the width dimension T2 of
the sensitive region E (the magnetic read track width M-Tw).
[0594] However, the electrode layers 318 and 318 formed to extend
over the multilayer film 316 must not extend into the sensitive
region E.
[0595] The sense current flows out, chiefly from the tip of the
electrode layer 318 extending over the multilayer film 316. When
the electrode layers 318 and 318 are formed on the sensitive region
E that substantially exhibits the magnetoresistive effect, the area
of the sensitive region E covered with the electrode layer 18
permits the sense current to less flow. The sensitive region E that
presents an otherwise excellent magnetoresistive effect is partly
degraded, and a drop in the reproduction output occurs. Since the
area of the sensitive region E covered with the electrode layer 318
still has some sensitivity, a variation in the magnetoresistance
occurs in both ends of the magnetic read track width M-Tw,
inconveniently generating noise.
[0596] FIG. 36 shows a multilayer film 322 in a spin-valve type
thin-film device of a twenty-first embodiment of the present
invention shown in FIG. 36, in which the order of the lamination of
the multilayer film 316 of the spin-valve type thin-film device
shown in FIG. 35 is inverted. Specifically, a free magnetic layer
314, a nonmagnetic electrically conductive layer 313, a pinned
magnetic layer 312, and an antiferromagnetic layer 320 are
successively laminated from the substrate 319 as shown in FIG.
36.
[0597] In the twenty-first embodiment, the free magnetic layer 314
of the multilayer film 322 shown in FIG. 36 is formed below the
antiferromagnetic layer 320, and is in contact with the thick
portion of the hard bias layers 317 and 317. The magnetization of
the free magnetic layer 314 is thus easily aligned in the X
direction. The generation of Barkhausen noise is thus
controlled.
[0598] In the twenty-first embodiment, again, the intermediate
layers 321 and 321, made of a high-resistivity material having a
resistance higher than that of the electrode layers 318 and 318 or
an insulating material, are interposed between the hard bias layers
317 and 317 and the electrode layers 318 and 318, and the shunting
of the sense current from the electrode layer 318 into the hard
bias layer 317 is controlled. As in the magnetoresistive-effect
device shown in FIG. 35, the nonmagnetic material layers 323 and
324, made of Ta, may be laminated under and over the intermediate
layer 321.
[0599] The electrode layers 318 and 318 are formed to extend over
the multilayer film 322, specifically extends over the insensitive
region D of the multilayer film 322 by a width dimension of T5.
[0600] In the twenty-first embodiment, the multilayer film 322 is
produced by successively laminating the free magnetic layer 314,
the nonmagnetic electrically conductive layer 313, the pinned
magnetic layer 312, and the antiferromagnetic layer 320 in that
order from below. The sense current flowing to the nonmagnetic
electrically conductive layer 313 from the electrode layer 318
formed on the multilayer film 322 is also shunted to the pinned
magnetic layer 312 and the antiferromagnetic layer 320, formed over
the nonmagnetic electrically conductive layer 313. The sense
current flowing into the nonmagnetic electrically conductive layer
313 can be reduced from the one flowing in the
magnetoresistive-effect device of FIG. 35 in which the free
magnetic layer 314 only is formed over the nonmagnetic electrically
conductive layer 313.
[0601] In the twenty-first embodiment, however, the intermediate
layers 321 and 321, formed between the hard bias layers 317 and 317
and the electrode layers 318 and 318, control the sense current
shunting into the hard bias layer 317. With the electrode layers
318 and 318 extending over the multilayer film 322, the sense
current directly flows from the electrode layer 318 to the
multilayer film 322. Furthermore, since the electrode layers 318
and 318 extend over the insensitive regions D and D, the sense
current is allowed to predominantly flow into the sensitive region
E. The magnetoresistive-effect device of this embodiment results in
a high reproduction gain and a high reproduction output, compared
with the conventional magnetoresistive-effect device shown in FIG.
33, in which the multilayer film 9 is produced by successively
laminating the free magnetic layer 4, the nonmagnetic conductive
layer 3, the pinned magnetic layer 2 and the antiferromagnetic
layer 1 in that order from below.
[0602] The use of the thin electrode layer 318, having a thickness
of h5, formed in contact with the multilayer film 322 reduces the
size of a step between the top surface of the electrode layer 318
and the top surface of the multilayer film 322. This arrangement
allows an upper gap layer 379 to be formed over the border area
between the electrode layer 318 and the multilayer film 322 with an
improved step coverage and with no film discontinuity involved, and
provides sufficient insulation.
[0603] FIG. 37 is a cross-sectional view showing the construction
of the magnetoresistive-effect device of a twenty-second embodiment
of the present invention, viewed from an ABS side thereof.
[0604] In a spin-valve type thin-film device shown in FIG. 37, an
antiferromagnetic layer 330 is formed over and along a substrate
319 in the X direction, and has a projected portion having a height
d1 on the center thereof. Laminated on the projected portion of the
antiferromagnetic layer 330 are a pinned magnetic layer 331, a
nonmagnetic electrically conductive layer 332, a free magnetic
layer 333, and a protective layer 315 to form a multilayer film
335.
[0605] The antiferromagnetic layer 330 is made of a Pt--Mn
(platinum-manganese) alloy. Instead of the Pt--Mn alloy, the
antiferromagnetic layer 330 may be made of an X--Mn alloy where X
is a material selected from the group consisting of Pd, Ir, Rh, Ru,
and alloys thereof, or a Pt--Mn--X' alloy where X' is a material
selected from the group consisting of Pd, Ir, Rh, Ru, Au, Ag, and
alloys thereof.
[0606] The pinned magnetic layer 331 and the free magnetic layer
333 are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt), an
Fe--Co (iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the
nonmagnetic electrically conductive layer 332 is made of a low
electrical-resistance nonmagnetic electrically conductive material,
such as Cu (copper).
[0607] Referring to FIG. 37, metallic layers 336 and 336, made of
Cr or the like, and functioning as a buffer layer or a alignment
layer, extend from a horizontal portion thereof coextending a width
dimension T8 of the antiferromagnetic layer 330 in the X direction,
rising along the side end faces of the pinned magnetic layer 331,
the nonmagnetic electrically conductive layer 332, and the free
magnetic layer 333. The use of the metallic layer 336 helps
increase the strength of the bias magnetic field created by hard
bias layers 337 and 337.
[0608] Deposited on the metallic layers 336 and 336 are hard bias
layers 337 and 337, made of a Co--Pt (cobalt-platinum) alloy or a
Co--Cr--Pt (cobalt-chromium-platinum) alloy.
[0609] In the magnetoresistive-effect device shown in FIG. 37, the
hard bias layers 337 and 337 are deposited on the antiferromagnetic
layer 330. The thickness of the hard bias layers 337 and 337,
formed on both sides of the free magnetic layer 333, are thicker
than the counterparts in the spin-valve type thin-film devices
shown in FIG. 35 and FIG. 36. The hard bias layers 337 and 337 give
a sufficient bias magnetic field to the free magnetic layer 333,
permitting the free magnetic layer 333 to be correctly shifted into
a single-domain state in the x direction.
[0610] The intermediate layers 338 and 338, made of a
high-resistivity material having a resistance higher than that of
the electrode materials 339 and 339 or an insulating material, are
separated from the hard bias layers 337 and 337 by the nonmagnetic
material layers 325 and 325, made of Ta. The electrode layers 339
and 339, made of Ta or Cr, are then respectively separated from the
intermediate layers 338 and 338 by the nonmagnetic material layers
326 and 326.
[0611] In the twenty-second embodiment, again, the intermediate
layers 338 and 338, formed between the hard bias layers 337 and 337
and the electrode layers 339 and 339, control the sense current
shunting into the hard bias layer 337. With the electrode layers
339 and 339 extending over the multilayer film 335, the electrode
layer 339 is electrically connected to the multilayer film 335 on
the top surface thereof. The sense current is directly conducted to
the multilayer film 335 from the electrode layer 339 on the
multilayer film 335 without passing the hard bias layer 337. The
magnetoresistive-effect device thus results in a high reproduction
gain and a high reproduction output.
[0612] Referring to FIG. 37, the portion of the multilayer film 335
having a width dimension T9 is the sensitive region E while the
portions of the multilayer film 335 having a width dimension T10
are the insensitive regions D and D. Since the electrode layers 339
and 339 extend over the insensitive regions D and D, the sense
current is allowed to predominantly flow into the sensitive region
E. This arrangement further increases the reproduction output.
[0613] Referring to FIG. 37, the electrode layer 339 on the
multilayer film 335 does not fully cover the insensitive region D,
with its width dimension T11 smaller than that of each insensitive
region D. As already discussed, the insensitive region D may be
fully covered with the electrode layer 339.
[0614] When the electrode layer 339 on the multilayer film 335 does
not fully cover the insensitive region D as shown in FIG. 37, the
optical read track width O-Tw, which is defined as the width
dimension of the top surface of the multilayer film 335 not covered
with the electrode layer 339, becomes larger than the magnetic read
track width M-Tw, which is defined as the width dimension of the
sensitive region E not covered with the electrode layer 339.
[0615] The use of the intermediate layer 338 permits the thickness
h6 of the electrode layer 339 to be made thinner relative to the
multilayer film 335 and thereby reduces the size of a step between
the top surface of the electrode layer 339 and the top surface of
the multilayer film 335. This arrangement allows an upper gap layer
379 to be formed over the border area between the electrode layer
339 and the multilayer film 335 with an improved step coverage and
with no film discontinuity involved, and provides sufficient
insulation.
[0616] FIG. 38 is a cross-sectional view showing a twenty-third
embodiment of the magnetoresistive-effect device of the present
invention, viewed from an ABS side thereof.
[0617] This spin-valve type thin-film device is a so-called dual
spin-valve type thin-film device, which includes a free magnetic
layer 344, nonmagnetic electrically conductive layers 345 and 343
respectively lying over and under the free magnetic layer 344,
pinned magnetic layers 346 and 342 respectively lying over and
under the nonmagnetic electrically conductive layers 345 and 343,
and antiferromagnetic layers 347 and 341 respectively lying over
and under the pinned magnetic layers 346 and 342. The dual
spin-valve type thin-film device provides a reproduction output
higher in level than that of the spin-valve type thin-film devices
(i.e., so-called single spin-valve type thin-film devices) shown in
FIG. 35 through FIG. 37. The layer lying at the bottom is the
substrate 319, while the layer lying on the top is a protective
layer 315. The laminate, composed of the layers from the substrate
319 through the protective layer 315, constitutes a multilayer film
348.
[0618] The antiferromagnetic layers 341 and 347 are preferably made
of a PtMn alloy. Instead of the Pt--Mn alloy, the antiferromagnetic
layers 314 and 347 may be made of an X--Mn alloy where X is a
material selected from the group consisting of Pd, Ir, Rh, Ru, and
alloys thereof, or a. Pt--Mn--X' alloy where X' is a material
selected from the group consisting of Pd, Ir, Rh, Ru, Au, Ag, and
alloys thereof.
[0619] The pinned magnetic layers 342 and 346 and the free magnetic
layer 344 are made of an Ni--Fe (nickel-iron) alloy, Co (cobalt),
an Fe--Co (iron-cobalt) alloy, or an Fe--Co--Ni alloy, and the
nonmagnetic electrically conductive layer 343 and 345 are made of a
low electrical-resistance nonmagnetic electrically conductive
material, such as Cu (copper).
[0620] Referring to FIG. 38, hard bias layers 349 and 349 are
formed on both sides of the multilayer film 348, and are made of a
Co--Pt (cobalt-platinum) alloy or a Co--Cr--Pt
(cobalt-chromium-platinum) alloy.
[0621] The hard bias layers 349 and 349 are magnetized in the X
direction (i.e., the direction of a track width), and the
magnetization of the free magnetic layer 344 is aligned in the X
direction under the bias magnetic field in the X direction from the
hard bias layers 349 and 349.
[0622] Intermediate layers 350 and 350 are formed to be separated
from the hard bias layers 349 and 349 by nonmagnetic material
layers 327 and 327, made of Ta. Each of the intermediate layers 350
and 350 is made of a high-resistivity material having a resistance
higher than that of electrode layers 351 and 351, for example, a
material selected from the group consisting of TaSiO.sub.2, TaSi,
CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and TaN, or is made of an
insulating material selected from the group consisting of
Al.sub.2O.sub.3, SiO.sub.2, T.sub.2O.sub.31, TiO, WO, AlN,
Si.sub.3N.sub.4, B.sub.4C, SiC, and SiAlON. The electrode layers
351 and 351, made of. Ta or Cr, are then respectively separated
from the intermediate layers 350 and 350 by the nonmagnetic
material layers 328 and 328.
[0623] Referring to FIG. 38, the electrode layers 351 and 351
extend over the multilayer film 348.
[0624] The intermediate layers 350 and 350, made of the
high-resistivity material or the insulating material, formed
between the hard bias layers 349 and 349 and the electrode layers
351 and 351, control the sense current shunting into the hard bias
layer 349. With the electrode layers 351 and 351 extending over the
top surface of the multilayer film 348, the sense current directly
flows from the electrode layer 351 to the multilayer film 348. The
magnetoresistive-effect device thus results in a high reproduction
gain and a high reproduction output.
[0625] Even if the thickness h3 of the electrode layer 350 formed
in contact with the multilayer film 340 is made smaller, the use of
the intermediate layer 350 permits the sense current to flow from
the electrode layer 351 to the multilayer film 348 without passing
through the hard bias layer 349. This arrangement reduces the size
of a step between the top surface of the electrode layer 351 and
the top surface of the multilayer film 348, and forms an upper gap
layer 379 over the border area between the electrode layer 351 and
the multilayer film 348, with an improved step coverage and with no
film discontinuity involved, and provides sufficient
insulation.
[0626] In the twenty-third embodiment, the sensitive region E and
insensitive regions D and D of the multilayer film 348 are measured
using the micro track profile. The portion having a width dimension
T15 centrally positioned in the multilayer film 348 as shown in
FIG. 38 is the sensitive region E, while the portions, each having
a width dimension T14, are the insensitive regions D and D.
[0627] In the sensitive region E, the magnetization of the pinned
magnetic layers 342 and 346 is correctly pinned in the Y direction
as shown. Since the magnetization of the free magnetic layer 344 is
correctly aligned in the X direction, the magnetization of the
pinned magnetic layers 342 and 346 is perpendicular to the
magnetization of the free magnetic layer 344. The magnetization of
the free magnetic layer 344 varies sensitively in response to an
external magnetic field from the recording medium. An electrical
resistance varies in accordance with the relationship between the
variation in the magnetization direction of the free magnetic layer
344 and the pinned magnetic field of the pinned magnetic layers 342
and 346. A leakage magnetic field from the recording medium is thus
detected in response to a variation in voltage due to the
electrical resistance variation.
[0628] Referring to FIG. 38, the electrode layers 351 deposited on
the multilayer film 348 respectively extend over the insensitive
regions D and D by a width dimension T16.
[0629] The width dimension of the top surface of the multilayer
film 348 not covered with the electrode layer 351 is defined as the
optical read track width O-Tw. The width dimension T15 of the
sensitive region E is defined as the magnetic read track width
M-Tw. In this embodiment, the electrode layers 451 and 451
deposited on the multilayer film 348 respectively fully cover the
insensitive regions D and D. The optical read track width O-Tw and
the magnetic read track width M-Tw (i.e., the width dimension of
the sensitive region E) are approximately equal to each other.
[0630] It is not a requirement that the electrode layers 351 and
351 fully cover the insensitive regions D and D. The width
dimension T15 of the electrode layer 351 extending over the
multilayer film 348 is smaller than the insensitive region D. In
this case, the optical read track width O-Tw becomes larger than
the magnetic read track width M-Tw.
[0631] This arrangement allows the sense current to predominantly
flow from the electrode layer 351 into the sensitive region E,
thereby increasing the reproduction output.
[0632] FIG. 39 is a cross-sectional view of a twenty-fourth
embodiment of the magnetoresistive-effect device of the present
invention, viewed from an ABS side thereof.
[0633] The magnetoresistive-effect device shown in FIG. 39 is
called an anisotropic magnetoresistive-effect (AMR) device. A soft
magnetic layer (a SAL layer) 352, a nonmagnetic layer (a shunt
layer) 353, a magnetoresistive layer (MR layer) 354, and a
protective layer 355 are successively laminated in that order from
below to form a multilayer film 361. Hard bias layers 356 and 356
are formed on both sides of the multilayer film 361. Typically, the
soft magnetic layer 352 is made of an NiFeNb alloy, the nonmagnetic
layer 353 is made of Ta, the magnetoresistive layer 354 is made of
an NiFe alloy, and the hard bias layers 356 and 356 are made of a
CoPt alloy.
[0634] Intermediate layers 357 and 357 are formed to be separated
from the hard bias layers 356 and 356 by nonmagnetic material
layers 329 and 329, made of Ta. Each of the intermediate layers 357
and 357 is made of a high-resistivity material having a resistance
higher than that of electrode layers 358 and 358, for example, a
material selected from the group consisting of TaSiO.sub.2, TaSi,
CrSiO.sub.2, CrSi, WSi, WSiO.sub.2, TiN, and TaN, or is made of an
insulating material selected from the group consisting of
Al.sub.2O.sub.3, SiO.sub.2, Ti.sub.2O.sub.3, TiO, WO, AlN,
Si.sub.3N.sub.4, B.sub.4C, SiC, and SiAlON. The electrode layers
358 and 358, made of Ta or Cr, are then respectively separated from
the intermediate layers 357 and 357 by the nonmagnetic material
layers 362 and 362.
[0635] Referring to FIG. 39, the electrode layers 358 and 358
extend over the multilayer film 361.
[0636] In the AMR device, the hard bias layer 356 is magnetized in
the X direction as shown, and the magnetoresistive layer 354 is
supplied with the bias magnetic field in the X direction by the
hard bias layer 356. Furthermore, the magnetoresistive layer 354 is
supplied with the bias field in the Y direction by the soft
magnetic layer 352. With the magnetoresistive layer 354 supplied
with the bias magnetic fields in the X direction and Y direction, a
variation in magnetization thereof in response to a variation in
the magnetic field becomes linear. The direction of the advance of
the recording medium is aligned with the Z direction. When a
leakage magnetic field from the recording medium in the Y direction
is applied, the magnetization direction of the magnetoresistive
layer 354 varies, causing a variation in the resistance. The
resistance variation is then detected as a voltage variation.
[0637] In the twenty-fourth embodiment of the present invention,
the intermediate layers 357 and 357, made of the high-resistivity
material or the insulating material, formed between the hard bias
layers 356 and 356 and the electrode layers 358 and 358, control
the sense current shunting into the hard bias layer 356. With the
electrode layers 358 and 358 extending over the top surface of the
multilayer film 361, the sense current directly flows from the
electrode layer 358 to the multilayer film 361.
[0638] Since the sense current flows to the multilayer film 361
from the electrode layer 358 formed on and in contact with the
multilayer film 361, the percentage of the sense current flowing
into the magnetoresistive layer 354 formed as the top layer of the
multilayer film 361 is increased. The shunting of the sense current
to the soft magnetic layer 352, which is a typical problem in the
conventional art, is thus controlled. Compared with the
conventional art, this invention thus achieves a high reproduction
gain and a high reproduction output.
[0639] Even if the thickness h4 of the electrode layer 358 is made
thin relative to that of the multilayer film 361, the use of the
intermediate layer 357 permits the sense current to effectively
flow from the electrode layer 358 to the multilayer film 361
without passing through the hard bias layer 356. This arrangement
reduces the size of a step between the top surface of the electrode
layer 358 and the top surface of the multilayer film 361, and forms
an upper gap layer 379 over the border area between the electrode
layer 358 and the multilayer film 361, with an improved step
coverage and with no film discontinuity involved, and provides
sufficient insulation.
[0640] In the twenty-fourth embodiment, the sensitive region E and
insensitive regions D and D of the multilayer film 361 are measured
using the micro track profile. The portion having a width dimension
T19 centrally positioned in the multilayer film 361 is the
sensitive region E, while the portions, each having a width
dimension T20, are the insensitive regions D and D.
[0641] Referring to FIG. 39, in this invention, the electrode layer
358 deposited on the multilayer film 361 extends over the
insensitive region D by a width dimension T21.
[0642] The width dimension of the top surface of the multilayer
film 361 not covered with the electrode layers 358 and 358 is
defined as the optical read track width O-Tw. The width dimension
T19 of the sensitive region E not covered with the electrode layers
358 and 358 is defined as the magnetic read track width M-Tw. In
this embodiment, the electrode layers 358 and 358 extending over
the multilayer film 361 fully cover the insensitive regions D and
D. The optical read track width O-Tw and the width dimension T19 of
the sensitive region E (the magnetic read track width M-Tw) are
approximately equal to each other.
[0643] It is not a requirement that the electrode layers 358 and
358 fully cover the insensitive regions D and D. The width
dimension T21 of the electrode layer 358 extending over the
multilayer film 361 may be smaller than the insensitive region D.
In this case, the optical read track width O-Tw becomes larger than
the magnetic read track width M-Tw.
[0644] With the electrode layers 358 and 358 extending over the
insensitive regions D and D of the multilayer film 361, the sense
current predominantly flows into the sensitive region E of the
magnetoresistive layer 354, thereby increasing the reproduction
output.
[0645] The method of manufacturing the magnetoresistive-effect
device of the present invention is now discussed referring to
drawings.
[0646] Referring to FIG. 40, a multilayer film 371 of the
magnetoresistive-effect device is formed on a substrate 370. The
multilayer film 371 can be any of the multilayer films of the
single spin-valve type thin-film devices shown in FIGS. 35 and 36,
and the multilayer film of the dual spin-valve type thin-film
devices shown in FIG. 38, and the multilayer film of the AMR
devices shown in FIG. 39. To form the antiferromagnetic layer 330
in its extended form in the X direction as shown in FIG. 37, an
etch rate and etch time are controlled to leave the side portions
of the antiferromagnetic layer 330, when the sides of the
multilayer film 371, shown in FIG. 40, are etched away. When the
multilayer film 371 is a multilayer film for a single spin-valve
type thin-film device or a dual spin-valve type thin-film device,
the antiferromagnetic layer 330 in the multilayer film 371 is
preferably made of a PtMn alloy, or may be made of an X--Mn alloy
where X is a material selected from the group consisting of Pd, Ir,
Rh, Ru, and alloys thereof, or a Pt--Mn--X' alloy where X' is a
material selected from the group consisting of Pd, Ir, Rh, Ru, Au,
Ag, and alloys thereof. When the antiferromagnetic layer is made of
one of the above-cited materials, the antiferromagnetic layer needs
to be subjected to a heat treatment to generate an exchange
coupling magnetic field in the interface with the pinned magnetic
layer.
[0647] FIG. 33 shows a conventional magnetoresistive-effect device
having its hard bias layers and electrode layers on only both sides
of the multilayer film. The width dimension A of the top surface of
the multilayer film of the conventional magnetoresistive-effect
device is measured using the optical microscope as shown in FIG.
31. The magnetoresistive-effect device is then scanned across a
micro track having a signal recorded thereon, on a recording medium
in the direction of the track width, and a reproduction output is
detected. A top width dimension of B giving an output equal to or
greater than 50% of a maximum reproduction output is defined as the
sensitive region E and a top width dimension of C giving an output
smaller than 50% of the maximum reproduction output is defined as
the insensitive region D.
[0648] Based on these measurement results, a lift-off resist layer
372 is formed on the multilayer film 371, paying attention to the
width dimension C of the insensitive regions D and D measured
through the micro track profile method. Referring to FIG. 40,
undercuts 372a and 372a are formed on the underside of the resist
layer 372. The undercuts 372a and 372a are formed above the
insensitive regions D and D, and the sensitive region E of the
multilayer film 371 is fully covered with the resist layer 372.
[0649] In a manufacturing step shown in FIG. 41, both sides of the
multilayer film 371 are cut away by etching, and in a manufacturing
step shown in FIG. 42, hard bias layers 373 and 373 are formed on
both sides of the multilayer film 371. In this invention, the
sputtering technique, used to form the hard bias layers 373 and
373, intermediate layers 376 and 376, and electrode layers 375 and
375, is preferably at least one sputtering technique selected from
an ion-beam sputtering method, a long-throw sputtering method, and
a collimation sputtering method.
[0650] In accordance with the present invention, as shown in FIG.
42, a substrate 370 having the multilayer film 371 formed thereon
is placed normal to a target 374 having the same composition as
that of the hard bias layers 373 and 373. In this setup, the hard
bias layers 373 and 373 are grown in a direction normal to the
multilayer film 371 using the ion-beam sputtering method, for
instance. The hard bias layers 373 and 373 are not grown into the
undercuts 372a and 372a of the resist layer 372 arranged on the
multilayer film 371. Referring to FIG. 42, a layer 373a having the
same composition as that of the hard bias layers 373 and 373 is
formed on top of the resist layer 372.
[0651] Intermediate layers 376 and 376 are grown on the hard bias
layers 373 and 373 through ion-beam sputtering method. In this
case, the target 374 is replaced with a target 377 having the
composition of a high-resistivity material selected from the group
consisting of TaSiO.sub.2, TaSi, CrSiO.sub.2, CrSi, WSi,
WSiO.sub.2, TiN, and TaN, or an insulating material selected from
the group consisting of Al.sub.2O.sub.3, SiO.sub.2,
Ti.sub.2O.sub.3, TiO, WO, AlN, Si.sub.3N.sub.4, B.sub.4C, SiC, and
SiAlON. The intermediate layers 376 and 376 are not deposited into
the undercuts 372a and 372a of the resist layer 372 arranged on the
multilayer film 371. As shown in FIG. 42, a layer 376a having the
same composition as that of the intermediate layers 376 and 376 is
formed on the resist layer 372.
[0652] In a manufacturing step shown in FIG. 43, the electrode
layers 375 and 375 are obliquely grown on the hard bias layers
intermediate layers 376 and 376 at an angle to the multilayer film
371. In this case, the electrode layers 375 and 375 are grown into
the undercuts 372a and 372a formed on the underside of the resist
layer 372 arranged on top of the multilayer film 371.
[0653] Referring to FIG. 43, the electrode layers 375 and 375 are
deposited on the hard bias layers 373 and 373 through the ion beam
splutter method, while the substrate 370, having the multilayer
film 371 thereon, is rotated in a plane at an angle with respect to
a target 378 having the same composition as that of the electrode
layer 375. The electrode layer 375 sputtered at an oblique angle is
grown not only on the intermediate layer 376 but also into the
undercut 372a of the resist layer 372 formed on the multilayer film
371. Specifically, the electrode layer 375 grown into the undercut
372a covers the insensitive region D of the multilayer film
371.
[0654] In a manufacturing step shown in FIG. 44, the resist layer
372 shown in FIG. 43 is removed using a resist stripper, and this
completes a magnetoresistive-effect device having the electrode
layers 375 and 375 formed on top of the insensitive regions D and D
of the multilayer film 371.
[0655] In accordance with the present invention, the intermediate
layer, made of a high-resistivity material having a resistance
higher than that of the electrode layer or an insulating materia,
is formed between the hard bias layer and the electrode layer. With
the electrode layer formed to extend over the multilayer film, the
sense current shunting to the hard bias layer is controlled, and
the sense current directly flows from the electrode layer to the
multilayer film. The magnetoresistive-effect device of this
invention thus presents a high reproduction gain and a high
reproduction output, compared with the conventional art.
[0656] The use of the intermediate layer permits the thickness of
the electrode in the contact area thereof with the multilayer film
to be thinned. This arrangement reduces the size of a step between
the top surface of the electrode layer and the top surface of the
multilayer film, and forms an upper gap layer over the border area
between the electrode layer and the multilayer film, with an
improved step coverage and with no film discontinuity involved, and
provides sufficient insulation.
[0657] The electrode layers overlapping the multilayer film are
formed to extend over the insensitive regions that occupy both end
portions of the multilayer film. In this arrangement, the sense
current predominantly flows into the sensitive region that is
centrally positioned in the multilayer film and substantially
exhibits the magnetoresistive effect. The reproduction output is
even further increased.
* * * * *