U.S. patent application number 10/191484 was filed with the patent office on 2003-03-20 for thin film magnetic head, magnetic head device, magnetic recording/reproducing device and method for fabricating a thin film magnetic head.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Kamijima, Akifumi, Shimazawa, Koji, Terunuma, Koichi.
Application Number | 20030053265 10/191484 |
Document ID | / |
Family ID | 19056167 |
Filed Date | 2003-03-20 |
United States Patent
Application |
20030053265 |
Kind Code |
A1 |
Terunuma, Koichi ; et
al. |
March 20, 2003 |
Thin film magnetic head, magnetic head device, magnetic
recording/reproducing device and method for fabricating a thin film
magnetic head
Abstract
A magnetoresistive effective film responds commensurate with an
external magnetic field. Magnetic domain-controlling films apply a
perpendicular biasing magnetic field to the magnetoresistive
effective film. The forefronts of first electrode films
constituting a pair of electrode films are overlaid on the
magnetoresistive effective film, and the forefront surfaces of the
first electrode films are risen at an inner angle of .theta.1.
Second electrode films are overlaid on the first electrode films,
and the forefront surfaces of the second electrode films are risen
at an inner angle of .theta.2 smaller than the inner angle
.theta.1.
Inventors: |
Terunuma, Koichi; (Chuo-ku,
JP) ; Shimazawa, Koji; (Chuo-ku, JP) ;
Kamijima, Akifumi; (Chuo-ku, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
19056167 |
Appl. No.: |
10/191484 |
Filed: |
July 10, 2002 |
Current U.S.
Class: |
360/322 ; 216/22;
29/603.15; G9B/5.115; G9B/5.124; G9B/5.135 |
Current CPC
Class: |
Y10T 29/49046 20150115;
G11B 5/3932 20130101; G11B 5/3967 20130101; G11B 5/3903
20130101 |
Class at
Publication: |
360/322 ;
29/603.15; 216/22 |
International
Class: |
G11B 005/39 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2001 |
JP |
2001-222731 |
Claims
What is claimed is:
1. A thin film magnetic head comprising a reading element including
a magnetoresistive effective film to respond commensurate with an
external magnetic head, a pair of magnetic domain-controlling films
to apply a perpendicular biasing magnetic field to said
magnetoresistive effective film and a pair of electrode films, each
composed of a first electrode film and a second electrode film, a
forefront of said first electrode film being overlaid on said
magnetoresistive effective film, a forefront surface of said first
electrode film being risen at an inner angle of .theta.1, said
second electrode film being formed on said first electrode film, a
forefront surface of said second electrode film being risen at an
inner angle .theta.2 smaller than said inner angle .theta.1.
2. A thin film magnetic head as defined in claim 1, wherein said
forefront surface of said second electrode film is discontinued
from said forefront surface of said first electrode film so that
said forefront surfaces of said second electrode film and said
first electrode film shape kinked line.
3. A thin film magnetic head as defined in claim 1, wherein said
inner angle .theta.1 is set within 40-90 degrees.
4. A thin film magnetic head as defined in claim 1, wherein said
inner angle .theta.2 is set to 45 degrees or below.
5. A thin film magnetic head as defined in claim 1, wherein the
thickness of said first electrode film is set smaller than the
thickness of said second electrode film.
6. A thin film magnetic head as defined in claim 5, wherein the
thickness of said first electrode film is set within 5-20 nm.
7. A thin film magnetic head as defined in claim 5, wherein the
thickness of said second electrode film is set within 10-50 nm.
8. A thin film magnetic head as defined in claim 1, wherein said
first and said second electrode films are mainly made of Au.
9. A thin film magnetic head as defined in claim 1, wherein said
reading element further includes a hard film on said second
electrode film.
10. A thin film magnetic head as defined in claim 9, wherein said
hard film is made of at least one selected from the group
consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Pd, Cu,
Si and Al.
11. A thin film magnetic head as defined in claim 9, wherein the
thickness of said hard film is set within 1-50 nm.
12. A thin film magnetic head as defined in claim 9, wherein said
reading element further includes an oxide film formed on said hard
film.
13. A thin film magnetic head as defined in claim 12, wherein said
oxide film is made of at least one selected from the group
consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Pd, Cu,
Si and Al.
14. A thin film magnetic head as defined in claim 12, wherein the
thickness of the oxide film is set within 1-10 nm.
15. A thin film magnetic head as defined in claim 1, further
comprising a slider to support said reading element.
16. A thin film magnetic head as defined in claim 1, further
comprising a writing element made of an inductive type magnetic
conversion element.
17. A magnetic head device comprising a thin film magnetic head as
defined in claim 1 and a head supporting device to support said
thin film magnetic head.
18. A magnetic recording/reproducing drive device comprising a
magnetic head device as defined in claim 17 and a magnetic disk to
be magnetically recorded and reproduced with said magnetic head
device.
19. A method for fabricating a thin film magnetic head comprising a
reading element including a magnetoresistive effective film to
respond commensurate with an external magnetic head, a pair of
magnetic domain-controlling films to apply a perpendicular biasing
magnetic field to said magnetoresistive effective film and a pair
of electrode films, each composed of a first electrode film and a
second electrode film, a forefront of said first electrode film
being overlaid on said magnetoresistive effective film, a forefront
surface of said first electrode film being risen at an inner angle
of .theta.1, said second electrode film being formed on said first
electrode film, a forefront surface of said second electrode film
being risen at an inner angle .theta.2 smaller than said inner
angle .theta.1, comprising the steps of: forming said
magnetoresistive effective film and said magnetic
domain-controlling films, forming a first conductive film to be
processed to said first electrode film on said magnetoresistive
effective film and said magnetic domain-controlling films, forming
a resist mask for lift off on said first conductive film and above
said magnetoresistive effective film, forming said second electrode
film on said first conductive film via said resist mask by means of
sputtering, removing said resist mask and etching said first
conductive film by means of reactive ion etching using said second
electrode film as a mask, to form said first electrode film,
thereby to complete said reading element.
20. A fabricating method as defined in claim 19, wherein said
forefront surface of said second electrode film is discontinued
from said forefront surface of said first electrode film so that
said forefront surfaces of said second electrode film and said
first electrode film shape kinked line.
21. A fabricating method as defined in claim 19, wherein said inner
angle .theta.1 is set within 40-90 degrees.
22. A fabricating method as defined in claim 19, wherein said inner
angle .theta.2 is set to 45 degrees or below.
23. A fabricating method as defined in claim 19, wherein the
thickness of said first electrode film is set smaller than the
thickness of said second electrode film.
24. A fabricating method as defined in claim 23, wherein the
thickness of said first electrode film is set within 5-20 nm.
25. A fabricating method as defined in claim 23, wherein the
thickness of said second electrode film is set within 10-50 nm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a thin film magnetic head, a
magnetic head device, a magnetic recording/reproducing device and a
method for fabricating a thin film magnetic head.
[0003] 2. Related Art Statement
[0004] In a magnetic recording field, a thin film magnetic head
having a spin-valve film (hereinafter, called as a "SV film") as a
reading element is mainly employed for developing the recording
density and the miniaturization.
[0005] The SV film is composed of a pinned layer, a non-magnetic
layer and a free layer which are stacked in turn. The magnetization
of the pinned layer is fixed in a given direction, and the
magnetization of the free layer is rotated commensurate with an
external magnetic field. The resistance of the SV film is minimized
as the direction of the magnetization of the pinned layer is
parallel to that of the free layer, and the resistance of the SV
film is maximized as the direction of the magnetization of the
pinned layer is anti-parallel to that of the free layer. Therefore,
a given external magnetic field is detected by measuring the change
in resistance as the free layer is rotated.
[0006] In addition, a magnetic domain-controlling film is prepared
to apply a perpendicular biasing magnetic field to the free layer.
In this case, the free layer is made single domain to prevent
Barkhausen noise due to the movement of magnetic wall. The magnetic
domain-controlling film may be made of a given antiferromagnetic
film. In this case, the perpendicular biasing magnetic field is
applied through the bonding with exchange interaction between the
antiferromagnetic film and the magnetic film constituting the free
layer. Moreover, the magnetic domain-controlling film may be made
of a hard magnetic film. In this case, the perpendicular biasing
magnetic field is applied from the hard magnetic film. The former
biasing means is called as exchange biasing method, and the latter
biasing means is called as hard magnetic biasing method.
[0007] In the area of the SV film adjacent to the magnetic
domain-controlling film, only the perpendicular biasing magnetic
field is generated larger, and a longitudinal biasing magnetic
field is not almost generated to form a non-sensitive region, which
does not function as a sensor and increase the electric resistance
of the magnetic resistive sensor circuit. As the electric
resistance of the magnetic resistive sensor circuit is increased,
the performance of the magnetic resistive sensor circuit is
restricted and electro-migration due to large current density may
occur.
[0008] In order to decrease the electric resistance of the
non-sensitive region, a so-called lead overlaying structure where
electrode films are provided at both sides of the SV film beyond
the non-sensitive region.
[0009] In order to realize the lead overlaying structure, such
technique is disclosed in Japanese Patent Application Laid-open No.
Tokukai Hei 11-53716 (JP A 11-53716) as that a first electrode film
not constituting a lead overlaying structure is formed on a
magnetic domain-controlling film, and a second electrode film
constituting the lead overlaying structure is formed on the first
electrode film by means of reactive ion etching (RIE).
[0010] With the above technique, however, since the second
electrode film is formed by means of RIE, the rising angle of the
second electrode film becomes large to be 60-80 degrees.
[0011] In a thin film magnetic head having such a lead overlaying
structure, a gap film made of an inorganic film is formed on
electrode films and a magnetoresistive effective film by means of
sputtering, and a shielding film is formed on the gap film. When
the rising angle of a second electrode film is set within 60-80
degrees as mentioned above, however, the gap film can not be formed
sufficiently thick at the rising surface of the second electrode
film, so that electric insulation can not be created between the
second electrode film and the shielding film to be formed on the
gap film.
[0012] In order to realize the lead overlaying structure, such a
technique is also disclosed in Japanese Patent Application
Laid-open No. 2000-276718 as to form an electrode film constituting
a lead overlaying structure by means of lift-off.
[0013] With the lift-off technique, however, the lead overlaying
structure is formed in wedge so that the electrode film is risen
from on the magnetoresistive effective film by a constant angle,
and thus, the forefront of the electrode film is formed in thin
blade. Therefore, a large current density is generated at the
blade-shaped forefront of the electrode film, and thus,
electro-migration due to the larger current density may occur.
SUMMARY OF THE INVENTION
[0014] It is an object of the present invention to provide a thin
film magnetic head, a magnetic head device, a magnetic
recording/reproducing drive device where the reliability in
electric insulation between the top shielding film and the
electrode film, and a method for fabricating the thin film magnetic
head.
[0015] It is another object of the present invention to provide a
thin film magnetic head, a magnetic head device and a magnetic
recording/reproducing drive device where electro-migration due to
large current density can be prevented, and a method for
fabricating the thin film magnetic head.
[0016] In order to achieve the above objects, a thin film magnetic
head according to the present invention includes a reading element
including a magnetoresistive effective film to respond commensurate
with an external magnetic head, a pair of magnetic
domain-controlling films to apply a perpendicular biasing magnetic
field to the magnetoresistive effective film and a pair of
electrode films.
[0017] Each electrode film is composed of a first electrode film
and a second electrode film. The forefront of the first electrode
film is overlaid on the magnetoresistive effective film, and the
forefront surface of the first electrode film is risen at an inner
angle of .theta.1.
[0018] The second electrode film is formed on the first electrode
film. The forefront surface of the second electrode film is risen
at an inner angle .theta.2 smaller than said inner angle
.theta.1.
[0019] In the thin film magnetic head of the present invention, the
reading element includes a magnetoresistive effective film to
respond commensurate with an external magnetic field and a pair of
electrode films. The forefront of each electrode film is overlaid
on the magnetoresistive effective film. Therefore, a given sense
current is supplied to the magnetoresistive effective film through
the pair of electrode films, and thus, a given signal can be
generated commensurate with an external magnetic field.
[0020] The reading element also includes a magnetic
domain-controlling film to apply a perpendicular biasing magnetic
field to the magnetoresistive effective film. With the
perpendicular biasing magnetic field, a magnetic sensitive film
constituting the magnetoresistive effective film is made single
domain, and thus, Barkhausen noise due to the movement of magnetic
wall can be prevented.
[0021] The pair of electrode films includes first electrode films,
respectively, of which the forefronts are overlaid on the
magnetoresistive effective film. In this case, since by setting
appropriately the overlaying degree of the first electrode films,
the first electrode films are formed beyond the non-sensitive
regions of the magnetic domain-controlling films which are formed
at the edge portions thereof, a given lead overlaying structure can
be realized. Therefore, the performance of the thin film magnetic
head can be enhanced, and the electro-migration due to large
current density can be prevented.
[0022] The pair of electrode films also includes second electrode
films, respectively, which are overlaid on the respective first
electrode films and of which the forefronts are risen at an inner
angle of .theta.2. On the other hand, the first electrode films are
risen from on the magnetoresistive effective film at an inner angle
.theta.1. The inner angle .theta.2 is set smaller than the inner
angle .theta.1. Conversely, the inner angle .theta.1 is set larger
than the inner angle .theta.2.
[0023] In this case, the thicknesses of the forefronts of the first
electrode films overlaying on the magnetoresistive effective film
can be increased to prevent the blade shapes of the forefronts of
the first electrode films. Therefore, a current density at the
forefronts of the first electrode films can be reduced
sufficiently, and thus, electro-migration due to large current
density can be prevented.
[0024] Since the rising angle .theta.2 of the second electrode film
is smaller than the rising angle .theta.1, the gap film can be
formed thick at the forefront of the first electrode film through
the wide opening of the second electrode film when the gap film is
formed on the second electrode film and the magnetoresistive
effective film by means of e.g., sputtering, so electric insulation
failure between the top shielding film and the electrode films due
to not sufficient thickness of the gap film can be prevented.
[0025] The magnetoresistive effective film may be composed of an
anisotropy magnetoresistive effective film, but preferably composed
of a SV film in view of the high density recording and the
miniaturization of a magnetic disk drive device.
[0026] The inner angle .theta.1 of the first electrode film is
preferably set within 40-90 degrees, and the inner angle .theta.2
of the second electrode film is preferably set to 45 degrees or
below.
[0027] In the case of fabricating the above-mentioned thin film
magnetic head, first of all, the magnetoresistive effective film
and the magnetic domain-controlling films are formed by means of
normal film-forming technique, and then, a first conductive film to
construct the first electrode films later is formed on the
magnetoresistive effective film and the magnetic domain-controlling
films.
[0028] Then, a resist mask for lift-off is formed on the first
conductive film and above the magnetoresistive effective film.
[0029] Then, the second electrode films are formed on the first
conductive film via the resist mask by means of sputtering.
[0030] Then, the resist mask is lifted off, and the first
conductive film is etched by means of reactive ion etching (RIE)
using the second electrode films as a mask to form the first
electrode films.
[0031] Thereafter, requisite steps are carried out for the thin
film magnetic to complete the above-mentioned thin film magnetic
head.
[0032] According to the fabricating method as mentioned above, the
thin film magnetic head can be easily and precisely fabricated.
[0033] This invention also relates to a magnetic head device and a
magnetic recording/reproducing drive device including the above
thin film magnetic head. These and other objects, features and
advantages of the present invention will become more apparent upon
the following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] For a better understanding of this invention, reference is
made to the attached drawings, wherein:
[0035] FIG. 1 is a perspective view showing a thin film magnetic
head according to the present invention,
[0036] FIG. 2 is an enlarged cross sectional view showing the thin
film magnetic head illustrated in FIG. 1,
[0037] FIG. 3 is an enlarged structural view showing the reading
element of the thin film magnetic head illustrated in FIGS. 1 and
2,
[0038] FIG. 4 is an enlarged structural view showing another
reading element of a thin film magnetic head according to the
present invention,
[0039] FIG. 5 is an explanatory view showing one step in
fabricating a reading element of a thin film magnetic head
according to the present invention,
[0040] FIG. 6 is an explanatory view showing the next step after
the step shown in FIG. 5,
[0041] FIG. 7 is an explanatory view showing the next step after
the step shown in FIG. 6,
[0042] FIG. 8 is an explanatory view showing the next step after
the step shown in FIG. 7,
[0043] FIG. 9 is an explanatory view showing the next step after
the step shown in FIG. 8,
[0044] FIG. 10 is an elevational view showing a portion of a
magnetic head device according to the present invention,
[0045] FIG. 11 is a bottom view showing the magnetic head device
illustrated in FIG. 10, and
[0046] FIG. 12 is a plan view showing a magnetic
recording/reproducing drive device according to the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0047] This invention will be described in detail, with reference
to the drawings, hereinafter. FIG. 1 is a perspective view showing
a thin film magnetic head according to the present invention. FIG.
2 is an enlarged cross sectional view showing the thin film
magnetic head illustrated in FIG. 1. FIG. 3 is an enlarged
structural view showing the reading element of the thin film
magnetic head illustrated in FIGS. 1 and 2. In this embodiment, the
thin film magnetic head includes a reading element 3 and a writing
element 2 made of an inductive type MR element which are formed on
a slider 1.
[0048] The slider 1 is constructed of a ceramic structural body,
and composed of a base made of as Al.sub.2O.sub.3--TiC, etc., and
an insulating film made of Al.sub.2O.sub.3 or SiO.sub.2 formed on
the base. The slider 1 has air bearing surfaces (hereinafter,
called as "ABS"s) 13 and 14 which are opposed to a magnetic
recording medium. In FIG. 1, the ABSs 13 and 14 are composed of
rails 11 and 12 to generate a positive pressure type airflow. The
ABSs 13 and 14 may be formed so as to have various geometrical
shapes to generate e.g., negative pressure type airflow. This
invention can be applied for any types of slider.
[0049] The writing element 2 includes a bottom magnetic film 21
doubling as a top shielding film, a top magnetic film 22, a coil
film 23, a gap film 24 made of alumina or the like, an insulating
film 25 and a protective film 26 which are stacked on a second gap
film 33 made of alumina or the like. The forefronts of the bottom
magnetic film 21 and the top magnetic film 22 constitute pole
portion P1 and P2 which are opposed each other, and when a magnetic
recording disk (not shown) is rotated at high speed, writing
operation is carried out by utilizing the pole portion P1 and
P2.
[0050] The bottom magnetic film 21 and the top magnetic film 22 are
joined at a back gap portion located at the opposite side to the
pole portions P1 and P2 to complete a magnetic circuit. A coil film
23 is formed on the insulating film 25 so as to whirl around the
back gap portion. The depicted writing element 2 is just one
embodiment, and this invention is not restricted to the writing
element 2 as mentioned above.
[0051] The reading element 3 includes a magnetoresistive effective
film 300, a pair of magnetic domain-controlling films 311 and 312,
and a pair of electrode films 35 and 36. In this embodiment, the
reading element 3 is located between the second gap film 33 and a
first gap film 32. The first and the second gap films are made of
alumina or the like and formed on a bottom shielding film 31 which
is formed on the slider base. In this embodiment, the reading
element 3 is formed on the writing element 2, but the other way
round will do.
[0052] The magnetoresistive effective film 300 is constructed as a
response film for an external magnetic field, and thus, made of an
anisotropy magnetoresistive effective film (AMR film) or a SV film.
In this embodiment, the magnetoresistive effective film 300 is made
of a SV film. As of now, various types of SV film are proposed in
stacking structure and/or film composition, and practically used.
This invention can be applied for any types of SV film.
[0053] The SV film is fundamentally composed of a pinned layer, a
non-magnetic layer, and a free layer which are stacked in turn. The
magnetization of the pinned layer is fixed in one direction, and
the magnetization of the free layer is rotated freely commensurate
with an external magnetic field. In the SV film, the resistance
becomes minimum as the direction of the magnetization of the pinned
layer is parallel to that of the free layer, and the resistance
becomes maximum as the direction of the magnetization of the pinned
layer is anti-parallel to that of the free layer. Therefore, the
external magnetic field can be detected by measuring the resistance
change.
[0054] In this embodiment, the SV film is composed of a free layer
301, a non-magnetic layer 302, a pinned layer 303 and an
antiferromagnetic layer 304 which are stacked in turn. In this
case, adjacent to the antiferromagnetic layer 304, the
magnetization of the pinned layer 303 (ferromagnetic layer) is
fixed in one direction.
[0055] When an external magnetic field is applied to the
magnetoresistive effective film 300 made of the SV film, the
magnetization of the free layer 301 is rotated commensurate with
the strength of the external magnetic field. The resistance of the
SV film is determined on the relative angle in magnetization
between the pinned layer 303 and the free layer 301. The resistance
of the SV film becomes maximum as the direction of the
magnetization of the free layer 301 is anti-parallel to that of the
pinned layer 303, and becomes minimum as the direction of the
magnetization of the free layer 301 is parallel to that of the
pinned layer 303. In this case, since the sense current Is is
changed commensurate with the resistance change of the SV film, a
given external magnetic field can be detected by measuring the
sense current Is.
[0056] The magnetic domain-controlling films 311 and 312 are joined
with both edge sides of the free layer 301. The magnetic
domain-controlling films 311 and 312 are made of antiferromagnetic
films or hard magnetic films. In this embodiment, the magnetic
domain-controlling films 311 and 312 are made of hard magnetic
films. A CoPt film and a CoPtCr film may be exemplified as the hard
magnetic film.
[0057] A given sense current is supplied to the magnetoresistive
effective film 300 via the pair of electrode films 35 and 36. The
electrode films 35 and 36 include first electrode films 351, 361
and second electrode films 352, 362, respectively. The forefronts
of the first electrode films 351 and 361 are overlaid on the
magnetoresistive effective film 300 by an overlaying degree of
.DELTA.L, and the forefront surfaces of the first electrode films
351 and 361 are risen at an inner angle of .theta.1, to form a lead
overlaying structure. In this embodiment, since the free layer 301
is located at the top of the magnetoresistive effective film 300,
the first electrode films 351 and 361 are overlaid on the free
layer 301, and risen from on the free layer 301 at the inner angle
.theta.1.
[0058] The second electrode films 352 and 362 are overlaid on the
first electrode films 351 and 361, and the forefront surfaces
thereof are risen at an inner angle of .theta.2 smaller than the
inner angle .theta.1.
[0059] As mentioned above, the reading element 3 includes the
magnetoresistive effective film 300 to respond commensurate with an
external magnetic field and the pair of electrode films 35 and 36
of which the forefronts are overlaid on the film 300. Therefore, a
given sense current Is is supplied to the magnetoresistive
effective film 300 through the pair of electrode films 35 and 36,
and a given signal commensurate with the external magnetic field
can be detected.
[0060] The reading element 3 includes the pair of magnetic
domain-controlling films 311 and 312 to apply a perpendicular
biasing magnetic field to the magnetoresistive effective film 300.
Therefore, the free layer 301 of the magnetoresistive effective
film 300 is made single domain, so that Barkhausen noise due to the
movement of magnetic domain can be prevented.
[0061] As mentioned above, the electrode films 35 and 36 include
first electrode films 351 and 361, respectively of which the
forefronts are overlaid on the magnetoresistive effective film 300
by the overlaying degree .DELTA.L. Therefore, by setting
appropriately the overlaying degree .DELTA.L, the electrode films
35 and 36 can be formed beyond non-sensitive regions of the
magnetic domain-controlling films 311 and 312 which are formed at
the edge portions, to form a lead over-laying structure. Therefore,
the performance of the thin film magnetic head can be enhanced and
electro-migration due to large current density can be
prevented.
[0062] The electrode films 35 and 36 also includes second electrode
films 352 and 362 which are overlaid on the first electrode films
351 and 361, and risen at the inner angle of .theta.2 which is set
smaller than the inner angle .theta.1.
[0063] In this case, the increase ratio of thickness per unit
length of the forefronts of the first electrode films 351 and 361
can be enhanced to prevent the blade shapes of the forefronts of
the films 351 and 361, so that the current density at the
forefronts of the films 351 and 361 is reduced sufficiently and
thus, electro-migration due to large current density can be
prevented.
[0064] Since the rising angle .theta.2 of the second electrode
films 352 and 362 is smaller than the inner angle .theta.1, the gap
film 33 can be formed thick on the second electrode films 352, 362
and the magnetoresistive effective film 30 via the wide opening
located between the second electrode films 351 and 361 by means of
e.g., sputtering, so that electric insulation failure between the
top shielding film (bottom magnetic film) and the electrode films
35, 36, which is originated from the small thickness of the gap
film 33, can be prevented.
[0065] The inner angle .theta.1 of the first electrode films 351
and 361 is preferably set within 40-90 degrees, and the inner angle
.theta.2 of the second electrode films 352 and 362 is preferably
set to 40 degrees or below.
[0066] In the present invention, since the first electrode films
351, 361 and the second electrode films 352, 362 are stacked, the
inner angles .theta.1 and .theta.2 within the above range can be
easily realized.
[0067] As shown in FIG. 3, in this embodiment, the forefront
surfaces of the second electrode films 352 and 362 are discontinued
from the forefront surfaces of the first electrode films 351 and
361. Therefore, the total forefront surfaces of the first and the
second electrode films have kinked line shapes, respectively.
[0068] In view of the reduction of electric resistance, the first
and the second electrode films are preferably made of a conductive
material containing Au as a main component.
[0069] Then, the technical significance of the inner angles
.theta.1 and .theta.2 will be described in detail, with reference
to examples and comparative examples.
[0070] 1. Inner Angle .theta.1
EXAMPLES 1-6
[0071] First of all, the first gap layer 32 was formed of
Al.sub.2O.sub.3 in a thickness of 30 nm on the bottom shielding
layer 31 made of NiFe (see, FIG. 2). Then, the magnetoresistive
effective film 300 was formed of a SV film on the first gap film
32, and the magnetic domain-controlling films 311 and 312 were
formed of CoPt at both edge portions of the film 300.
[0072] Then, the electrode films 35 and 36 were formed on the
magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312 to form a lead overlaying
structure, on which the second gap film 33 was formed of
Al.sub.2O.sub.3. Then, the top shielding film (bottom magnetic
film) 21 was formed on the second gap film 33.
[0073] In forming the lead overlaying structure with the electrode
films 35 and 36, the inner angle .theta.1 of the first electrode
films 351 and 361 was varied while the inner angle .theta.2 of the
second electrode film 352 and 362 was maintained constant.
COMPARATIVE EXAMPLES 1-2
[0074] The magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312 were formed in the same manner as
Examples. Then, the electrode films 35 and 36 were formed on the
magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312 by means of lift off, to form a
lead overlaying structure. Then, the second gap film 33 was formed
of Al.sub.2O.sub.3 on the electrode films 35 and 36. Then, the top
shielding film (bottom magnetic film) 21 was formed on the second
gap film 33. The electrode films 35 and 36 were made of their
respective single layers.
COMPARATIVE EXAMPLES 3-5
[0075] Except that the electrode films 35 and 36 were formed by
means of RIE, to form a lead overlaying structure, instead of the
lift off, the thin film magnetic head was fabricated in the same
manner in Comparative Examples 1-2.
[0076] Then, the voltages of dielectric breakdown and the
electro-migrations for the thin film magnetic heads fabricated in
Examples 1-6 and Comparative Examples 1-5 were measured. The
dielectric breakdown voltages were measured between the electrode
films 35, 36 and the top shielding film 21. The electro-migrations
were measured from the deformation of the edge portions of the
electrode films 35 and 36 which are exposed to the ABSs 13 and 14
(see, FIGS. 1 and 2) when a sense current Is of 6 mA was flown in
the magnetoresistive effective film 300 made of the SV film for 30
hours at 130.degree. C. The measured results were listed in Table
1.
1 TABLE 1 Voltage of Electro- dielectric migration breakdown x:
occurrence .theta.1 t1 .theta.2 t2 relative .smallcircle.: not
(deg.) (nm) (deg.) (nm) value occurrence Example 1 40 15 35 25 1.0
.smallcircle. Example 2 50 15 35 25 1.0 .smallcircle. Example 3 60
15 35 25 1.0 .smallcircle. Example 4 70 15 35 25 1.0 .smallcircle.
Example 5 80 15 35 25 1.0 .smallcircle. Example 6 90 15 35 25 1.0
.smallcircle. Comparative 30 40 -- -- 1.0 x Example 1 Comparative
40 40 -- -- 0.9 .smallcircle. Example 2 Comparative 50 40 -- -- 0.8
.smallcircle. Example 3 Comparative 60 40 -- -- 0.6 .smallcircle.
Example 4 Comparative 80 40 -- -- 0.4 .smallcircle. Example 5
[0077] Referring to Table 1, in Comparative Example 1 where the
inner angle .theta.1 is set to 30 degrees smaller than 40 degrees
and the electrode films 35 and 36 were made of single layers,
respectively, the dielectric breakdown voltage of the thin film
magnetic head is almost equal to those of the thin film magnetic
heads in Examples 1-6, but the electro-migration occurs, different
from Examples 1-6.
[0078] In Comparative Examples 2-5 where the inner angle .theta.1
is set more than 40 degrees and the electrode films 35 and 36 are
made of single layers, respectively, the dielectric breakdown
voltages of the thin film magnetic heads are decreased, but no
electro-migration occur. Therefore, it is turned out that large
electric insulation and prevention of electro-migration can not be
realized simultaneously as long as the electrode films are made of
the respective single layers if the lead overlaying structure is
formed by means of lift off or RIE.
[0079] In contrast, in Examples 1-6 where the electrode films 35
and 36 are made of the first electrode films 351, 361 and the
second electrode films 352, 362, respectively, which are stacked in
turn and the inner angle .theta.1 is set within 40-90 degrees,
large electric insulation and prevention of electro-migration can
be realized simultaneously.
[0080] 2. Inner Angle .theta.2
[0081] As mentioned above, the magnetoresistive effective film 300
and the magnetic domain-controlling films 311, 312 were formed.
Then, the electrode films 35 and 36 were formed on the
magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312, to form a lead overlaying
structure. Then, the second gap film 33 was formed of
Al.sub.2O.sub.3 on the electrode films 35 and 36. Then, the top
shielding film (bottom magnetic film) 21 was formed on the second
gap film 33.
[0082] In forming the lead overlaying structure with the electrode
films 35 and 36, the inner angle .theta.2 of the second electrode
films 352 and 362 was varied while the inner angle .theta.1 of the
first electrode film 351 and 361 was maintained constant.
[0083] Thin film magnetic heads satisfying the relation of
.theta.2.ltoreq.45 degrees were classified as Examples 7-10, and
thin film magnetic heads satisfying .theta.2>45 degrees were
classified as Comparative Examples 6 and 7.
[0084] The voltages of dielectric breakdown and the
electro-migrations for the thin film magnetic heads fabricated in
Examples 7-10 and Comparative Examples 6-7 were measured in the
same manner as mentioned above. The measured results were listed in
Table 2.
2 TABLE 2 Voltage of Electro- dielectric migration breakdown x:
occurrence .theta.1 t1 .theta.2 t2 relative .smallcircle.: not
(deg.) (nm) (deg.) (nm) value occurrence Example 7 60 15 35 25 1.0
.smallcircle. Example 8 60 15 45 25 1.0 .smallcircle. Example 9 80
15 35 25 1.0 .smallcircle. Example 10 80 15 45 25 1.0 .smallcircle.
Comparative 60 15 50 25 0.9 .smallcircle. Example 6 Comparative 80
15 50 25 0.9 .smallcircle. Example 7
[0085] As is apparent from Table 2, in Examples 7-10 where the
condition of .theta.2.ltoreq.45 degrees is satisfied, large
electric insulation and prevention of electro-migration can be
realized simultaneously. In contrast, in Comparative Examples 6 and
7 where the inner angle .theta.2 is set to 50 degrees and thus, the
condition of .theta.2.ltoreq.45 degrees is dissatisfied, the
dielectric breakdown voltages are decreased with comparison to
those in Examples 7-10 but no electro-migration occur.
[0086] It is desired that the thickness t1 of the first electrode
films 351, 361 and the thickness t2 of the second electrode films
352, 362 satisfy the relation of t1.ltoreq.t2. The thickness t1 of
the first electrode films 351 and 361 is set within 5-20 nm, and
the thickness t2 of the second electrode films 352 and 362 is set
within 10-50 nm. Therefore, the relation of t1.ltoreq.t2 is
satisfied within the above-mentioned thickness ranges. Next, the
technical significance of the relation of t1.ltoreq.t2 will be
described in detail hereinafter.
[0087] As mentioned above, the magnetoresistive effective film 300
and the magnetic domain-controlling films 311, 312 were formed.
Then, the electrode films 35 and 36 were formed on the
magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312, to form a lead overlaying
structure. Then, the second gap film 33 was formed of
Al.sub.2O.sub.3 on the electrode films 35 and 36. Then, the top
shielding film (bottom magnetic film) 21 was formed on the second
gap film 33.
[0088] In forming the lead overlaying structure with the electrode
films 35 and 36, the thickness t2 of the second electrode films 352
and 362 was varied while the thickness t1 of the first electrode
film 351 and 361 was maintained constant.
[0089] Thin film magnetic heads satisfying the relation of
t2.gtoreq.t1 were classified as Examples 11-14, and thin film
magnetic heads satisfying the relation of t2.ltoreq.t1 were
classified in Comparative Examples 8-9.
[0090] The voltages of dielectric breakdown and the
electro-migrations for the thin film magnetic heads fabricated in
Examples 11-14 and Comparative Examples 8-9 were measured in the
same manner as mentioned above. The measured results were listed in
Table 3.
3 TABLE 3 Voltage of Electro- dielectric migration breakdown x:
occurrence .theta.1 t1 .theta.2 t2 relative .smallcircle.: not
(deg.) (nm) (deg.) (nm) value occurrence Example 11 60 20 35 20 1.0
.smallcircle. Example 12 80 20 35 20 1.0 .smallcircle. Example 13
60 20 35 20 1.0 .smallcircle. Example 14 80 20 35 25 1.0
.smallcircle. Comparative 60 20 35 15 0.85 .smallcircle. Example 8
Comparative 80 20 35 15 0.8 .smallcircle. Example 9
[0091] As is apparent from Table 3, in Examples 11-14 where the
condition of t2.gtoreq.t1 is satisfied, large electric insulation
and prevention of electro-migration can be realized simultaneously.
In contrast, in Comparative Examples 8 and 9 where the relation of
t2<t1 is satisfied and thus, the condition of t2.gtoreq.t1 is
satisfied, the dielectric breakdown voltages are decreased with
comparison to those in Examples 11-14 but no electro-migration
occur.
[0092] FIG. 4 is an enlarged structural view showing a reading
element of a thin film magnetic head according to the present
invention. Like reference numerals are imparted to like constituent
elements, and detail explanation for like constituent elements will
be omitted. This embodiment is characterized by forming hard films
354 and 364 on the second electrode films 352 and 362. In this
case, the second electrode films 352 and 362 made of Au, etc.,
which have smaller hardness can be protected by sequential
manufacturing process damages. The hard films 354 and 364 have
larger hardness than the second electrode films 352 and 362. If the
second electrode films 352 and 362 are made of Au, the hard films
354 and 364 are made of a material larger in hardness than Au.
[0093] Concretely, if the second electrode films 352 and 362 are
mainly made of Au, the hard films 354 and 364 are preferably made
of at least one selected from the group consisting of Ti, Zr, Hf,
V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Pd, Cu, Si and Al. The thickness
of the hard films 354 and 364 is set within 1-50 nm.
[0094] In this embodiment, hard films 353 and 363 are formed
between the first electrode films 351, 361 and the magnetoresistive
effective film 300; the magnetic domain-controlling films 311, 312
and between the first electrode films 351, 361 and the second
electrode films 352, 362, respectively.
[0095] Not shown, a given oxide film may be formed on the hard
films 354 and 364. In this case, the reliability in electric
insulation between the second electrode films 352, 362 and the top
shielding film 21 can be developed. The oxide film may be made of
the same material as the hard films 354 and 364 as mentioned above.
The thickness of the oxide film is set within 1-10 nm.
[0096] Then, the fabricating method of thin film magnetic head will
be described with reference to FIGS. 5-9. In this embodiment, the
fabricating method for the above thin film magnetic head including
the reading element 3 will be mainly described.
[0097] First of all, as shown in FIG. 5, the magnetoresistive
effective film 300 and the magnetic domain-controlling films 311,
312 are formed by means of normal film-forming technique, and then,
a first conductive film 370 to be processed to the first electrode
films 351 and 361 later (see, FIGS. 3 and 4) is formed on the films
300, 311 and 312.
[0098] The first conductive film 370 is mainly made of Au by means
of sputtering, and the thickness of the film 370 is set within 5-20
nm. The first conductive film 370 may be formed on a given
underlayer made of Ta, etc., which is formed on the
magnetoresistive effective film 300 and the magnetic
domain-controlling films 311, 312.
[0099] Then, as shown in FIG. 6, a resist mask 380 for lift off is
formed on the first conductive film 370 and above the
magnetoresistive effective film 300 by means of
photolithography.
[0100] Then, as shown in FIG. 7, the second electrode films 352 and
362 are formed on the first conductive film 370 via the resist mask
380 by means of sputtering. In this case, an electrode film 390 is
deposited on the resist mask 380 through the sputtering
process.
[0101] In forming the second electrode films 352 and 362, sputtered
particles are introduced onto the first conductive film 370 by an
angle of .theta., so that the forefronts of the second electrode
films 352 and 362 are risen at the inner angle .theta.2. In the
case of fabricating the thin film magnetic head as shown in FIG. 4,
it is required that the hard films are formed before and after the
first electrode films are formed. In this case, therefore, the
film-forming processes for the hard films such as sputtering are
also required.
[0102] Then, the resist mask is removed, and thereafter, as shown
in FIG. 8, the first electrode film 370 is etched and patterned by
means of RIE using the second electrode films 352 and 362 as a
mask, to form the first electrode films 351 and 361 (see, FIGS. 3
and 4). The RIE process is carried out as plasma etching using
Ar/O.sub.2 gas mixture.
[0103] As a result, the overlaying degree of the first electrode
films 351 and 361 on the free layer 301 of the magnetoresistive
effective film 300 is set to .DELTA.L, and the rising angle of the
first electrode films 351 and 361 is set to the inner angle
.theta.1.
[0104] Since the first electrode films 351 and 361 are patterned by
using the second electrode films 352 and 362 as a mask, the inner
angle .theta.1 is set larger than the inner angle .theta.2.
[0105] Then, requisite fabricating processes are performed to form
a writing element 2 and thus, complete a thin film magnetic film.
Although in this embodiment, attention is paid to one thin film
magnetic head to be fabricated, in real fabricating process, the
above-mentioned fabricating process is carried out on one wafer to
fabricate plural thin film magnetic heads simultaneously.
[0106] FIG. 10 is an elevational view showing a portion of a
magnetic head device according to the present invention, and FIG.
11 is a bottom view showing the magnetic head device illustrated in
FIG. 10. The illustrated magnetic head device includes a thin film
magnetic head 4 as shown in FIGS. 1-4 according to the present
invention and a head supporting device 5.
[0107] The head supporting device 5 supports the thin film magnetic
head 4 at the under surface of a flexible member 51 made of a
metallic plate which is attached on the free edge thereof in the
long direction of a supporting member 53 made of a metallic
plate.
[0108] The flexible member 51 has two outer frames 55 and 56
extending along the long direction of the supporting member 53, a
side frame 54 to join the outer frames 55 and 56 at the edge
thereof, and a tongue-shaped member 52, of which one end is a free
edge, extending along the outer frames 55 and 56 from the center of
the side frame.
[0109] On the center of the tongue-shaped member 52 is positioned a
hemispherical loading protrusion 57, bulging on the supporting
member 53, to apply load to the tongue-shaped member 52.
[0110] The thin film magnetic head 4 is attached on the under
surface of the tongue-shaped member 52 so that it can have its air
outflow edge along the side frame 54. In the present invention, the
head supporting device 5 is not limited to the above
embodiment.
[0111] FIG. 12 is a plan view showing a magnetic
recording/reproducing drive device according to the present
invention. A magnetic recording/reproducing drive device depicted
in FIG. 12 includes a magnetic head device 6 as shown in FIGS. 10
and 11 and a magnetic disk 7. The magnetic head device 6 is driven
by a position determining device 8 which supports one end of the
device 5. The thin film magnetic head 4 of the magnetic head device
5 is supported by the head supporting device 5 so that it can face
the magnetic recording surface of the magnetic disk 7.
[0112] When the magnetic disk 7 is rotated in the A1 direction by a
driving device (not shown), the thin film magnetic head 4 is
floated from on the magnetic disk 7 by a minute distance. In this
case, rotary-actuator driving system is normally employed as a
driving mechanism, but linear-actuator driving system may be
employed. In this embodiment, the rotary-actuator driving system is
employed, and then, the thin film magnetic head 4 attached to the
free edge of the head supporting device 5 is driven in the radial
direction b1 or b2 of the magnetic disk 7 and positioned on a given
track by the position determining device 8.
[0113] Although the present invention was described in detail with
reference to the above examples, this invention is not limited to
the above disclosure and every kind of variation and modification
may be made without departing from the scope of the present
invention.
[0114] As mentioned above, according to the present invention,
[0115] (a) a thin film magnetic head, a magnetic head device, a
magnetic recording/reproducing drive device where the reliability
in electric insulation between the top shielding film and the
electrode film, and a method for fabricating the thin film magnetic
head can be provided, and
[0116] (b) a thin film magnetic head, a magnetic head device and a
magnetic recording/reproducing drive device where electro-migration
due to large current density can be prevented, and a method for
fabricating the thin film magnetic head can be provided.
* * * * *