U.S. patent application number 09/234508 was filed with the patent office on 2001-06-07 for a magnetoresistive element including a silicon and/or a diffusion control layer.
Invention is credited to HAYASHI, KAZUHIKO.
Application Number | 20010002869 09/234508 |
Document ID | / |
Family ID | 11752077 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002869 |
Kind Code |
A1 |
HAYASHI, KAZUHIKO |
June 7, 2001 |
A MAGNETORESISTIVE ELEMENT INCLUDING A SILICON AND/OR A DIFFUSION
CONTROL LAYER
Abstract
An MR (Magneto Resistance) effect element includes a free
magnetic layer having a small coercive force and therefore reduces
the hysteresis of the R-H loop. An MR effect sensor and an MR
sensing system using the above MR effect elenient and featuring a
desirable noise characteristic are also disclosed.
Inventors: |
HAYASHI, KAZUHIKO; (TOKYO,
JP) |
Correspondence
Address: |
MCGUIRE WOODS LLP
1750 TYSONS BOULEVARD
SUITE 1800
MCLEAN
VA
22102-4215
US
|
Family ID: |
11752077 |
Appl. No.: |
09/234508 |
Filed: |
January 21, 1999 |
Current U.S.
Class: |
360/324.12 ;
29/603.07; G9B/5; G9B/5.116 |
Current CPC
Class: |
G11B 5/00 20130101; G11B
2005/3996 20130101; H01F 10/3268 20130101; G01R 33/093 20130101;
G11B 5/3967 20130101; G11B 5/3903 20130101; Y10T 29/49032 20150115;
B82Y 10/00 20130101; B82Y 25/00 20130101; H01F 10/3295
20130101 |
Class at
Publication: |
360/324.12 ;
29/603.07 |
International
Class: |
G11B 005/39 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 1998 |
JP |
10505/1998 |
Claims
What is claimed is:
1. In an MR (Magneto Resistance) effect element, a laminate film is
implemented by a unit consisting of an Si layer, a metal lower
layer, a free magnetic layer, a nonmagnetic layer, a fixed layer,
and a magnetic fixing layer.
2. In an MR effect eleIent, a laminate film is implemented by a
unit consisting of an Si layer, a diffusion control layer, a metal
lower layer, a free magnetic layer, a nonmagnetic layer, a fixed
layer, and a magnetic fixing layer.
3. An MR effect element as claimed in claim 2, wherein said
diffusion control fayer comprises one of Ta, Hf, Zr, W, Cr, Ti, Mo,
Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au, Os, Pd, Mb and V.
4. An MR effect element as claimed in claim 2, wherein said
diffusion control layer comprises one of an oxide and a nitride of
Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W, Mo, Ni and Zn and a mixture
of said oxide and said nitride.
5. An MR effect element as claimed in claim 2, wherein said
diffusion control layer comprises one of a mixture and a raminate
of an oxide and a nitride of Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W,
Mo, Ni and Zn.
6. A method of producing an MR effect element, comprising the steps
of: sequentially forming an Si layer, a metal under layer and a
free magnetic layer on a substrate; heating a resulting lamniate at
a temperature between 100.degree. C. and 400.degree. C. in vacuum;
and sequentially forming a nonmagnetic layer, a magnetic fixed
layer, and a magnetic fixing layer.
7. A method of producing an MR effect element, comprising the steps
of: sequentially forming an Si layer, a diffusion control layer, a
metal under layer and a free magnetic layer on a substrate; heating
a resulting laminate at a temperature between 100.degree. C. and
400.degree. C. in vacuum; and sequentially forming a nonmagnetic
layer, a magnetic fixed layer, and a magnetic fixing layer.
8. A method as clainmd in claim 7, wherein said diffusion control
layer comprises Ta, Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co,
Zn, Ru, Rh, Re, Au, Os, Pd, Nb and V.
9. An MR effect element as claimed in claim 7, wherein said
diffusion control layer comprises one of an oxide and a nitride of
Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W, Mo, Ni and Zn and a mixture
of said oxide and said nitride.
10. An MR effect element as claimed in claim 7, wherein said
diffusion control layer comprises one of a mixture and a laminate
of an oxide and a nitride of Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W,
Mo, Ni and Zn.
11. A method of producing an MR effect element, comprising the
steps of: heating, at a time of sequentially forming an Si layer, a
metal under layer and a free magnetic layer on a substrate, said
substrate at a temperature between 100.degree. C. and 400.degree.
C.; and sequentially forming a nonmagnetic layer, a magnetic fixed
layer, and a magnetic fixing layer.
12. A method of producing an MR effect element, comprising the
steps of: heating, at a time of sequentially forming an Si layer, a
diffusion control layer, a metal under layer and a free magnetic
layer on a substrate, said substrate at a temperature between
100.degree. C. and 400.degree. C.; and sequentially forming a
nonmagnetic layer, a magnetic fixed layer, and a magnetic fixing
layer.
13. A method as claimed in claim 12, wherein said diffusion control
layer comprises Ta, Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co,
Zn, Ru, Rh, Re, Au, Os, Pd, Nb and V.
14. An MR effect element as claimed in claim 12, wherein said
diffusion control layer comprises one of an oxide and a nitride of
Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W, Mo, Ni and Zn and a mixture
of said oxide and said nitride.
15. An MR effect element as claimed in claim 12, wherein said
diffusion control layer oonprises one of a mixture and a laminate
of an oxide and a nitride of Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W,
Mo, Ni and Zn.
16. In an MR effect sensor, a lower shield layer, a lower gap layer
and an MR effect element are laminated on a substrate, said shield
layer and said MR effect element each being patterned, a
longitudinal bias layer and a lower electrode layer are
sequentially laminated in such a manner as to contact edges of said
MR effect element, and an upper gap layer and an upper shield layer
are sequentially laminated on said longitudinal bias layer and said
lower electrode layer.
17. An MR effect sensor as claimed in claim 16, wherein said MR
effect element comprises a laminate film implemented by a unit
consisting of an Si layer, a metal lower layer, a free magnetic
layer, a nonmagnetic layer, a fixed layer, and a magnetic fixing
layer.
18. An MR effect sensor as claimed in claim 16, wherein said MR
effect element comprises a laminate film implemented by a unit
consisting of an Si layer, a diffusion control layer, a metal lower
layer, a free magnetic layer, a nonmagnetic layer, a fixed layer,
and a magnetic fixing layer.
19. An MR effect sensor as claimed in claim 18, wherein said
diffusion control layer coiprises one of Ta, Hf, Zr, W, Cr, Ti, Mo,
Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au, Os, Pd, Nb and V.
20. An IR effect element as claimed in claim 18, wherein said
diffusion control layer comprises one of an oxide and a nitride of
Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W, Mo, Ni and Zn and a mixture
of said oxide and said nitride.
21. An MR effect element as claimed in claim 18, wherein said
diffusion control fayer comprises one of a mixture and a laminate
of an oxide and a nitride of Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W,
Mo, Ni and Zn.
22. In an MR effect sensor, a lower shield layer, a lower gap layer
and an MR effect element are laminated on a substrate, said shield
layer and said MR effect element each being patterned, a
longitudinal bias layer and a lower electrode layer are
sequentially laminated in such a manner as to partly overlap said
MR effect element, and an upper gap layer and an upper shield layer
are sequentially laminated on said longitudinal bias layer and said
lower electrode layer.
23. An MR effect sensor as claimed in claim 22, wherein said MR
effect element comprises a laminate film implemented by a unit
consisting of an Si layer, a metal lower layer, a free magnetic
layer, a nonmagnetic layer, a fixed layer, and a magnetic fixing
layer.
24. An MR effect sensor as claimed in claim 22, wherein said MR
effect element comprises a laminate film implemented by a unit
consisting of an Si layer, a diffusion control layer, a metal lower
layer, a free magnetic layer, a nonmagnetic layer, a fixed layer,
and a magnetic fixing layer.
25. An MR effect sensor as claimed in claim 24, wherein said
diffusion control layer comprises one of Ta, Hf, Zr, W, Cr, Ti, Mo,
Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au, Os, Pd, Nb and V.
26. An MR effect element as claimed in claim 24, wherein said
diffusion control layer comprises one of an oxide and a nitride of
Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W, Mo, Ni and Zn and a mixture
of said oxide and said nitride.
27. An MR effect element as claimed in claim 24, wherein said
diffusion control layer comprises one of a mixture and a laminate
of an oxide and a nitride of Si, Ta, Al, Ti, V, Cr, Mn, Hf, Zr, W,
Mo, Ni and Zn.
28. An MR sensing system comprising: an MR effect sensor comprising
a lower shield layer, a lower gap layer and an MR effect ele-nmnt
laminated on a substrate, said shield layer and said MR effiect
element each being patterned, a longitudinal bias layer and a lower
electrode layer sequentially laminated in such a manner as to
contact edges of said MR effect element, and an upper gap layer and
an upper shield layer sequentially laminated on said longitudinal
bias layer and said lower electrode layer; means for producing a
current to flow through said MR effect sensor; and means for
sensing a change in an MR ratio of said MR effect sensor as a
function of a magnetic field sensed.
29. An MR sensing system comprising: an MR effect sensor comprising
a lower gap layer and an MR effect element laminated on a
substrate, said shield layer and said MR effect eltment each being
patterned, a longitudinal bias layer and a lower electrode layer
sequentially laminated in such a manner as to partly overlap said
MR effect element, and an upper gap layer and an upper shield layer
sequentially laminated on said longitudinal bias layer and said
lower electrode layer; means for producing a current to flow
through said MR effect sensor; and means for sensing a change in an
MR ratio of card MR effect sensor as a function of a magnetic field
sensed.
30. A magnetic storage system comprising: a magnetic recording
medium having a plurality of tracks for recording data; a magnetic
recording system for writing data in said magnetic recording
medium; an MR sensing system comprising an MR effect sensor, means
for producing a current to flow through said MR effect sensor, and
means for sensing a change in an MR ratio of said MR effect sensor
as a function of an magnetic field sensed, said MR effect sensor
comprising a lower shield layer, a lower gap layer and an MR effect
element laminated on a substrate, said shield layer and said MR
effect eIement each being patterned, a longitudinal bias layer and
a lower electrode layer sequentially laminated in such a manner as
to contact edges of said MR effect element, and an upper gap layer
and an upper shield layer sequentially laminated on said
longitudinal bias layer and said lower electrode layer; and means
connected to said magnetic recording system and said MR sensing
system for effecting a movement to any one of the tracks of said
magnetic recording medium selected.
31. A magnetic storage system comprising: a magnetic recording
medium having a plurality of tracks for recording data; a magnetic
recording system for writing data in said magnetic recording
medium: an MR sensing system comprising an MR effect sensor, means
for producing a current to flow through said MR effect sensor, and
means for sensing a change in an MR ratio of said MR effect sensor
as a function of an magnetic field sensed, seid MR effect sensor
comprising a lower shield layer, a lower gap layer and an MR effect
element laminated on a substrate, said shield layer and said MR
effect element each being patterned, a longitudinal bias layer and
a lower electrode layer sequentially laminated in such a manner as
to partly overlap said MR effect element, and an upper gap layer
and an upper shield layer sequentially laminated on said
longitudinal bias layer and said lower electrode layer; and means
connected to said magnetic recarding system and said MR sensing
system for effecting a movement to any one of the tracks of said
magnetic recording medium selected.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a magnetic sensor for
reading data signals stored in a magnetic recording medium.
[0002] A magnetic read transducer called an MR (Magneto Resistance)
effect sensor or an MR effect head is conventional and capable of
reading data out of a magnetic surface with high linear density. as
reported in the past. The MR effect sensor or head senses a
magnetic field signal in terms of the variation of resistance which
is the function of the intensity and direction of a magnetic flux
sensed by a reading device. The conventional read transducer is
based on an AMR (Anisotropic Magneto Resistance) effect. i.e., the
fact that one component of the resistance of a reading device
varies in proportion to the square of the cosine of an angle
between the direction of magnetfzation and the direction of a sense
current flowing through the reading device.
[0003] For details of the AMR effect, reference may be made to D.
A. Thompson et al. "Memory, Storage, and Related Applications",
IEEE Trans. on Mag. MAG-11. p. 1039 (1975).
[0004] It is a common practice with a magnetic head utilizing the
AMR effect to apply a longitudinal bias magnetic field for reducing
Barkhausen noise. To apply the vertical bias magnetic field, use is
sometimes made of FeMn. NiMn, nickel oxide or similar
antiferromagnetic material. There has recently been reported a more
noticeable MR effct, i. e., the fact that the resistance of a
laminate magnetic sensor is ascribable to the spin-dependent
transfer of conductive electrons occurring between magnetic layers
via a nonmagnetic layer and spin-dependent diffusion occurring at
an interface between layers due to the above transfer. This kind of
MR effect is generally referred to as. e.g., a macro MR effect or a
spin valve effect.
[0005] The above MR sensor is formed of a suitable material and has
higher sensitivity than a sensor using the AMR effect and therefore
noticeably varies in resistance. In this kind of MR effect sensor,
two ferromagnetic layers are separated from each other by a
nonmagnetic layer. Resistance in the plane between the two
ferromagnetic layers varies in proportion to the cosine of an angle
between the magnetization directions of the ferromagnetic
layers.
[0006] Japanese Patent Laid-Open Publication No. 2-1572, for
example, discloses a laminate magnetic structure featuring high MR
variation based on the anti parallel alignment of magnetization in
a magnetic layer. As for materials usable for the laminate
structure, the above document mentions ferromagnetic transition
metals and alloys. Further, the document teaches a structure in
which an antiferromagnetic layer is added to one of at least two
ferromagnetic layers, and indicates that FeMn is feasible for the
antiferromagnetic foyer.
[0007] Japanese Patent Laid-Open Publication No. 4-358310 proposes
an MR sensor including two thin ferromagnetic layers separated from
eachotherbyathinrnonmagneticrmetal layer. When no magnetic field is
applied to this MR sensor, the magnetization directions of the two
ferromagnetic layers are perpendicular to each other. Resistance
between the two non-coupled ferromagnetic layers varies in
proportion to the cosine of the angle between the above
magnetization directions independently of the direction of current
flowing through the sensor.
[0008] Japanese Patent Laid-Open Publication No. 6-203340 discloses
an MR sensor also based on the above effect and including two thin
ferromagnetic layers separated by a nonmagnetic thin metal layer.
When the outside magnetic field is zero, the magnetization of an
adjoining antiferromagnetic layer remains perpendicular to the
magnetization of the other ferromagnetic layer.
[0009] Japanese Patent Laid-Open Publication No. 7-262529 teaches
an MR effect element or spin valve made up of a first magnetic
layer, a nonmagnetic layer, a second magnetic layer, and an
antiferromagnetic layer. For the first and second magnetic layers,
use is made of CoZrNb, CoZrMo, FeSiAl, FeSi or NiFe with or without
Cr, Mn, Pt, Ni, Cu, Ag, Al, Ti, Fe, Co or Zn added thereto.
[0010] Japanese Patent Laid-Open Publication No. 7-202292 proposes
an MR effect film including a plurality of magnetic thin films
laminated on a substrate and separated by a nonmagnetic layer. An
antiferrcmsignetic thin layer adjoins one of soft magnetic thin
films adjoining each other with the intermediary of a nonmagnetic
thin fiIm. Assume that a bias magnetic field applied to the
antiferromagnetic thin film is H.sub.r, and that the coercive force
of the other soft magnetic thin film is H.sub.c2. Then, a relation
H.sub.c2<H.sub.r holds. The antiferromagnetic material is
implemented by at least one of NiO, CoO, FeO, Fe.sub.2O.sub.3, MnO
and Cr or a mixture thereof.
[0011] Japanese Patent Laid-Open Publication No. 8-127864 teaches
an MR effect film similar to the above film except that the
antiferromagnetic thin layer is implemented as a superlattice
consisting of at least two of NiO, Ni.sub.xCo.sub.i-xO and CoO.
[0012] Further. Japanese Patent Laid-Open Publication No. 8-2O4253
discloses an MR effect film similar to the above film except that
the antiferromagnetic layer is a superlattice consisting of at
least two of NiO, Ni.sub.xCo.sub.i-xO=(x=0.1-0.9), and CoO. In the
superIattice, the ratio of Ni to Co in the number of atoms is
greater than 1.0 inclusive.
[0013] As for an effect MR element basically consisting of a free
magnetic layer. a nonmagnetic layer. a fixed magnetic layer and a
fixing magnetic layer, it is preferable that the free magnetic
layer has an easy axis of a uniaxial magnetic anisotropy
substantially perpendicular to the magnetization direction of the
fixed layer.
[0014] The above type of IR effect element should preferably be
designed and used such that the magnetization direction of the free
magnetic layer and that of the fixed layer are substantially
perpendicular to each other in a zero magnetic field. At this
instant, if the easy axis direction of the free magnetic layer and
the magnetization direction of the fixed layer make an angle c lose
to a right angle, then a magnetic field (leakage magnetic field
from a record mark on a magnetic recording medium with respect to
the operation of a read head) is applied in the hard axis direction
of the free magnetic layer. This successfully reduces the coercive
force of the free magnetic layer and thereby reduces the hysteresis
of the R-H loop when the MR effect element is used as a read
sensor. It is therefore possible to reduce the noise of a
reproduced signal.
[0015] However, many of the conventional MR elerents use an
antiferromagnetic material for the fixing layer. Further, many of
antiferromagnetic materials expected to be put to practical use as
a fixing layer must be heated at temperatures above 200.degree. C.
in a magnetic field parallel to the magnetization direction of the
fixed layer, so that a sufficient exchange coupled magnetic field
can be applied to the fixed layer.
[0016] In each of the conventional MR effect element of the type
described, the anti ferromagnetic layer is formed after the
formation of the free magnetic layer, nonmagnetic layer, and fixed
magnetic layer. Therefore, the above heat treatment acts not only
on the fixed magnetic layer and fixing magnetic layer but also on
the free magnetic layer. Consequently, the easy axis of the
uniaxial magnetic anisotropy of the free magnetic layer is oriented
parallel to the direction of the magnetic field, i.e., the
magnetization direction of the fixed magnetic layer. This increases
the coercive force of the free magnetic layer and thereby increases
noise when the MR effect film is used as a sensor.
[0017] Technologies relating to the present invention are a1so
disclosed in, e.g., Japanese Patent Laid-Open Publication No.
9-199326.
SUMMARY OF THE INVENTION
[0018] It is therefore an object of the present invention to
provide an MR effect element capable of reducing the coercive force
of its free magnetic layer and therefore the hysteresis of the R-H
loop, and an MR effect sensor and an MR sensing system using the
same and featuring a desirable noise characteristic.
[0019] In accordance with the present invention, in an MR effect
element, a laminate film is implemented by a unit consisting of an
Si layer, a metal lower layer, a free magnetic layer, a nonmagnetic
layer, a fixed layer, and a magnetic fixing layer.
[0020] Also, in accordance with the present invention, in an MR
effect element, a laminate film is implemented by a unit consisting
of an Si layer, a diffusion control layer, a metal lower layer, a
free magnetic layer, a nonmagnetic layer, a fixed layer, and a
magnetic fixing layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above and other objects, features and advantages of the
present invention will becnme more apparent from the following
detailed description taken with the accompanying drawings in
which:
[0022] FIGS. 1 and 2 each shows a particular typical configuration
of an MR sensor;
[0023] FIG. 3 is 8 perspective view showing the general
construction of a read/write head;
[0024] FIG. 4 shows the general configuration of a
recording/reproducing apparatus;
[0025] FIG. 5 is a table listing the coercive forces end saturation
magnetic fields of a free magnetic layer and magnetoresistance (MR)
ratios measured at different substrate temperatures;
[0026] FIGS. 6 and 7 are tables each listing the coercive forces
and saturation magnetic fields of free magnetic layer included in
samples and MR ratios measured after heat treatment;
[0027] FIG. 8 is a table listing the coercive forces and saturation
magnetic fields of a free magnetic layer and MR ratias measured at
different heat treatment temperatures (heat treatment temperatures
A);
[0028] FIG. 9 is a table listiing the coercive forces and
saturation magnetic fields of free magnetic layers included in
samples and MR ratios measured after heat treatment;
[0029] FIG. 10 is a table listing the coercive forces and
saturation magnetic fields of a free magrietic layer and MR ratios
measured at different substrate temperatures;
[0030] FIG. 11 is a table listing the coercive forces and
saturation magnetic fields of a free magnetic layer and MR ratios
measured at different heat treatment temperatures (heat treatment
temperatures B);
[0031] FIG. 12 is a table listing the coercive forces and
saturation magnetic fields of free magnetic layers included in
samples and MR ratios measured after heat treatment;
[0032] FIG. 13 is a table listing the coercive farces and
saturation magnetic fields of a free magnetic layer and MR ratios
in relation to different thicknesses of an alumina layer;
[0033] FIG. 14 is a table listing the coercive forces and
saturation magnetic fields of free magnetic layers included in
samples and MR ratios measured after heat treatment;
[0034] F FIG. 15 is a table listing the coercive forces and
saturation magnetic fields of a free magnetic tayer and MR ratios
in relation to diffusion control layers of different kinds;
[0035] FIG. 16 is a table listing the coercive forces and
saturation is magnetic fields of free magnetic layers included in
samples and MR ratios measured after heat treatment; and
[0036] FIGS. 17 and 18 are tables each listing the coercive forces
and saturation magnetic fields of a free magnetic layer and MR
ratios in relation to diffusion control layers of different
kinds.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] FIGS. 1 and 2 show two different typical shield type devices
to which the present invention is applied. The device shown in FIG.
1 includes a substrate 1. A lower shield layer 2, a lower gap layer
3 and MR effect element 6 sequentially laminated on the substrate
1. An insulating layer 7 for determining a gap may be formed on the
MR effect element 6. as the case may be. The lower shield layer 2
is, in many cases, patterned in a suitable size by a photoresist
(PR) step. The MR effect element 6 is also patterned in a suitable
size by a PR step. A longitudinal bias layer 4 and a lower
electrode layer 5 are sequentially formed in such a manner as to
contact the edges of the MR effect element 6. An upper gap layer 8
and an upper shield layer 9 are sequentially laminated on the
layers 4 and 5.
[0038] The device shown in FIG. 2 includes a lower shield layer 12,
a lower gap layer 13 and an MReffect element16 sequentiIlly
laminated on a substrate 11. The lower shield layer 12 is, in many
cases, patterned in a suitable size by a PR step. The MR effect
element 16 Is also patterned in a suitable size by a PR step, A
longitudinal bias layer 14 and a lower electrode layer 15 are
sequential ly formed in such a manner as to partly overlap the MR
effect element 16. An upper gap layer 18 and an upper shield layer
19 are sequentially laminated on the layers 14 and 15.
[0039] For the lower shield layer 2 or 12, use may be made of,
e.g., an NiFe, CoZr, CoFeB, CoZrMo, CpZrNb, CoZr. CoZrTa, CoHf,
GoTa, CoTaHf, CoNbHf. CoZrNb, CoHfPd, CoTaZrNb or CoZrMoNi alloy,
FeAlSi or iron nitride. The shield layer 2 or 12 should preferably
be 0.3 .mu.m to 10 .mu.m thick.
[0040] The lower gap layer 3 or 13 may advantageously be formed of,
e.g., alumina, SiO.sub.2, aluminum nitride, silicon nitride or
diamond-like carbon. The thickness of the lower gap layer 3 or 13
should preferably be 0.01 .mu.m to 0.20 .mu.m.
[0041] The lower electrode layer 5 or 15 may advantageously be
formed of Zr, Ta or Mo or an alloy or a mixture thereof. The lower
electrode layer 5 or 15 should preferably be 0.01 .mu.m to 0.10
.mu.m thick. For the longitudinol bias layer 4 or 14, use may be
made of CoCrPt, CoCr, CoPt, CoCrTa, FeMn, NiMn, IrMn, PtPdMn, ReMn,
PtMn, CrMn, Ni oxide. ion oxide, an Ni oxide and Co oxide mixture,
an Ni oxide and Fe oxide mixture, an Ni oxide and Co oxide film or
an Ni oxide and Fe oxide fiIm by way of example.
[0042] The insulating layer 7 for determining a gap may
advantageousIy be formed of alumina, Si0.sub.2, aluminum nitride,
silicon nitride or diamond-like carbon and shouId preferably be
0.005 .mu.m to 0.05 .mu.m thick.
[0043] The upper gap layer 8 or 18 may be formed of alumina,
SiO.sub.2, aluminum nitride, silicon nitride or diamond-like carbon
by way of example and should preferably be 0.01 .mu.m to 0.20 .mu.m
thick.
[0044] Further, the upper shield layer 9 or 19 may be formed of,
e.g., NiFe or CoZr or CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf,
CoTa, CoTaHf, CoNbHf, CoZrNb, CoHfPd, CoTaZrNb or CoZrMoNi alloy,
FeAlSi or ion nitride. The thickness of the upper shield layer 1 or
9 should preferably be between 0.3 .mu.m and 10 .mu.m.
[0045] The shield type devices shown in FIGS. 1 and 2 each can
implement a read/write head with an inductive coil forming a write
head portion.
[0046] FIG. 3 shows a specific configuration of a read/write head.
As shown, the read/write head is made up of a read head implemented
by the MR effect element of the present invention and an
interactive write head, While the MR effect element is combined
with the write head adapted for longitudinal magnetic recording, it
may be combi ned with a vertical write head used for vertical
magnetic recording.
[0047] Specifically. the head shown in FIG. 3 has a slider or base
21. A read head is formed on the slider 21 and made up of an upper
shield film 22, a lower shield film 23, an MR effect film 24. and
an electrode film 25. A write head is formed on the read head and
made up of an upper magnetic film 26, a lower magnetic film 27, and
a coil 28, The upper shield film 22 of the read head and the lower
magnetic film 27 of the write head may be implemented as a single
magnetic film, if desired.
[0048] The read/write head with the above configuration selectively
records signals in a magnetic recording medium or reproduces them
from the recording medium. As shown in FIG. 3, the sensing portion
of the read head and the magnetic gap of the write head lie one
above the other and can therefore be positioned at the same track
at the same time. After the slider has been machined, the
readJarite head is mounted to a support member, provided with
wirings, and then mounted to a magnetic recording/reproducing
apparatus.
[0049] FIG. 4 shows a specific configuration of a
recording/reproducing apparatus using the MR effect element of the
present invention. As shown. anr MR effect film 32 and an electrode
filIm 33 are formed on a base 31 playing the role of a head slider
30 at the same time. After the Lead slider 31 has been machinecd,
it is provided with wirings and then mounted to the apparatus. A
positioning mechanism, not shown, positions the head slider 30 at a
preselected track formed on a magnetic recording medium 34.
[0050] A drive motor, not shown, causes the recording medium 34 to
spin. The head slider 30 moves relative to the recording medium 34
at a height of 0.2 .mu.m or more above the medium 34 or in contact
with the medium 34. In this condition, the MR effect film 32 reads
a magnetic signal out of the recording medium 34 in the form of a
leakage magnetic field.
[0051] The MR element may have any one of the following different
structures (1) through (6):
[0052] (1) substrate/Si layer/metal under layer/free magnetic
layer/nonmagnetic layer/fixed magnetic layer/antiferromagnetic
layer/protection layer;
[0053] (2) substrate/Si layer/metal under layer/free magnetic
layer/first MR enhancing layer/nonmagnetic layer/fixed magnetic
layer/fixing layer/protection layer;
[0054] (3) substrate/Si layer/metal under layer/free magnetic
layer/first MR enhancing layer/normagnetic layer/second MR
enhancing layerlffed magnetic layer/fixing layer/protection
layer;
[0055] (4) substrate/Si layer/diffusion control foyer/metal under
layer/free magnetic layer/nonmagnetic layer/fixed magnetic
layer/antiferromagnetic layer/protection layer;
[0056] (5) substrate/Si layer/diffusion control layer/metal under
layer/free magnetic layer/first MR enhancing layer/nonmagnetic
layer/fixed magnetic layer/fixing layer/protection layer; and
[0057] (6) substrate/Si layer/diffusion control layer/metal under
layer/free magnetic layer/first MR enhancing layer/nonmagnetic
layer, second MR enhancing layer/fixed magnetic layer/fixing
layer/protection layer
[0058] For the diffusion control layer, use may be made of Ta, Hf,
Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au, Os,
Pd, Nb, V or similar metal, an oxide or a nitride of Si, Ta, Al,
Ti, V, Cr, Mn, Hf, W, Mo, Ni, Zn or similar metal, a mixture of the
ox ide and nitride, or a mixture or a laminate of the metal and
oxide and nitride mixture.
[0059] The metal under layer may be implemented by one or more
metals in the form of a single film or a laminate. Specifically,
use may be made of a single film, a mixture film or a laminate
consisting of Ta, Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co,
Zn, Ru, Rh, Re, Au, Os, Pd, Nb and V.
[0060] The free magnetic layer may be formed of NiFe, Cofe, NiFeCo,
FeCo, CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa, CoTaHf,
CoHbHf, CoZrNb, CoHfPd, CoTaZrNb or CoZrMoNi all oy or an amorphous
magnetic substance. This layer should preferably be about 1 nm to
10 nm thick.
[0061] As for the nonmagnetic layer, there may be used Cu with or
without about 1 at % to 20 at % of Ag added thereto. Cu with about
1 at % to 20 at % of Re added thereto or a Cu--Au alloy. The
nonmagnetic layer should preferably be 2 nm to 4 nm thick.
[0062] The first and second MR enhancing layers each may be formed
of Co, NiFeCo or FeCO, a CaFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf,
CaTa, CoTaHf, CoNbHf, CoZrNb, CoHfPd, CoTaZrNb or CoZrMoNi alloy,
or an amorphous magnetic material and should preferably be about
0.5 nm to 5 nm thick.
[0063] When neither the first nor the second MR enhancing layer is
present, the MR ratio decreases. However, the number of steps for
fabrication is successfully reduced due to the absence of the MR
enhancing layers. For the fixed magnetic layer, use nay be made of
metal selected from a group of Co-, Ni- and Fe-based materials or
an alloy or a laminate thereof. The fixed magnetic layer should
preferably be about 1 nm to 50 nm thick.
[0064] The fixing layer may be implemented by FeMn, NiMn, IrMn,
RhMn, PtPdMn, ReMn, PtMn, PtCrMn, CrMn, CrAl, TbCo, Ni oxide, Fe
oxide, Ni oxide and Co oxide mixture, Ni oxide and Fe oxide
mixture, laminate Ni oxide and Co oxide film, laminate Ni oxide and
Fe oxide film, CoCr, CoCrPt, CoCrTa or PtCo.
[0065] As for the protection layer, use is made of metal oxide or
nitride, an oxide and nitride mixture, or a laminate metal and
oxide film, a laminate metal and nitride film, or a laminate metal
and oxide and nitride mixture film. Other hopeful candidates are
Ti, V, Cr, Co, Cu, Zn, Y, Zr, Mb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta,
W, Re, Os, Ir, Pt or Au, or an oxide or a nitride selected from a
group consisting of Si, Al, Ti and Ta or a mixture thereof, or a
mixture of the above oxide, nitride or a mixture thereof and one
element or an ally of two or more elements selected frain a group
consisting of Ta, Hf, Zr, W, Cr, Ti, Mo, kPt, Hi, Ir, Cu, Ag, Co,
Zn, Ru, Rh, Re, Au, Os, Pd, Nb, V and Y and implemented as a
laminate film.
[0066] Examples of the present invention will be described
hereinafter. First, for comparison, an MR effect film lacking an Si
layer was produced. This MR film had a glass substrate/Ta (3
nm)/NiFe (6 nm) /CoFe (1 nm) /Cu (2.7 nm)/CoFe (3 nm) /FeMn (10
nm)/Ta (3 nm) structure. Magnetic fields different by 90 degrees
from each other were respectively applied to the NiFe (6 nm)/CoFe
(1 nm) portion and CoFe (3 nm)/FeMn (10 nm) portion at the time of
film formation.
[0067] A magnetic field parallel to the magnetic field used to form
the CoFe/FeMn portion was applied to the above MR effect film in
order to measure an R-H loop. The measurement showed that the free
magnetic layer had a coercive force of 1 Oe and a saturation
magnetic field of 5 Oe. The MR ratio was measured to be 7%.
[0068] On the other hand, whiIe a magnetic field of 500 Oe parallel
to the magnetic field used to form the CoFe/FeMn portion was
applied to the comparative MR affect film, the film was heated at
270.degree. C. for 5 hours in vacuum. As a result, the coercive
force of the free magnetic layer increased to 2.5 Oe while the
saturation magnetic field of the same decreased to 30 Oe. The
increase in coercive force and the decrease in saturation magnetic
field indicate that the anisotropy of the free magnetic layer
noticeably rotated in the direction of application of the magnetic
field during heat treatment. After the heat treatment, the MR ratio
was found to be 6%.
[0069] An MR effect element with a glass substrate/Si (10 nm) /Ta
(3 nm)/NiFe (6 nm)/CoFe (1 nm)/Cu (2.7 nm)/CoFe (3 nm) /FeMn (10
nm)/Ta (3 nm) structure was produced. Specifically, for the
Si/Ta/NiFe/CoFe portion, a magnetic field of about 100 Oe was
applied while the substrate temperature was varied. After the
sufficient cooling of this portion, the Cu/CoFe/FeMn/Ta portion was
formed.
[0070] FIG. 5 shows how the coercive force and saturation magnetic
field of the free magnetic layer and the MR ratio varied in
accordance with the substrate temperature. As shown, the coercive
force and saturation magnetic field tended to increase as the
substrate temperature rose although such a tendency was not clearly
accounted for. The MR ratio slowly decreased with the elevation of
substrate temperature up to 25o.degree. C., but sharply fell at
temperatures above 250.degree. C.
[0071] The above MR effect film was subjected to a magnetic field
of 500 Oe parallel to the magnetic field used to form the CoFe/FeMn
portion and was heated at 270.degree. C. (heat treatment
temperature B hereinafter) for 5 hours. FIG. 6 tabulates the
coercive forces and saturation magnetic fields of the free magnetic
fayer subjected to the heat treatment temperature B and MR ratios.
As shown, the coercive force decreased and the saturation magnetic
field increased at substrate temperatures of 150.degree. C. and
above. It will be seen that by the heat treatment effected at
temperatures of 150.degree. C. and above, the rotation of the free
magnetic layer in the direction of anisotropy and ascribable to the
Si layer can be reduced.
[0072] An MR effect element with a glass substrate/Si (10 nm)/Ta (3
nm)/NiFe (6 nm)/CoFe (1 nm)/Cu (2.7 nm)/CoFe (3 nm)/FeMn (10 nm)/Ta
(3 nm) structure was produced. After the formation of the
Si/Ta/NiFe/CoFe portion, the laminate was heated in a magnetic
field of about 100 Oe applied in the same direction as the magnetic
field used for film formation. After the sufficient cooling of this
portion, the Cu/CoFe/FeMn/Ta portion was formed.
[0073] FIG. 8 lists the coercive forces and saturation magnetic
fields of the free magnetic layer subjected to the above treatment
temperature Cheat treatment tenperature A hereinafter) and MR
ratios. As shown, the coercive force and saturation magnetic field
tended to increase with the elevation of heat treatment temperature
A in the same manner as when the substrate temperature was varied.
The MR ratio slowly decreases in accordance with the hs,at
treatment temperature up to 250.degree. C. but sharply fell at
temperatures above 250.degree. C.
[0074] A sample identical in configuration with the above MR effect
element was heated at 270.degree. C.(heat treatment temperature B)
for 5 hours in a magnetic field of 500 Oe parallel to the magnetic
field used to form the CoFe/FeMn portion. The resulting coercive
forces and saturation magnetic fields of the free magnetic layer
and MR ratios are listed in FIG. 9. As shown, at temperatures of
100.degree. C. and above, the coercive force and saturation
magnetic field of the free magnetic layer decreased and increased,
respectively, It will be seen that at temperatures higher than
100.degree. C. inclusive the rotation of the free magnetic layer in
the direction of anisotropy and ascribable to the Si layer can be
reduced.
[0075] An MR effect element with a glass substrate (10 nm)/alumina
(10 nm)/Ta (3 nm) NiFe (5 nm) /CoFe (1 nm)/Cu (2.7 nm) /CoFe (3
nm)/FeMn (10 nm)/Ta (3 cm) structure was produced. Specifically,
the Si/alumina/Ta/NiFe/CoFe portion was formed in a magnetic field
of 100 Oe with the substrate temperature being varied. After the
sufficient cooling of this portion, the Cu/CoFe/FeMn/Ta portion was
formed. Magnetic fields different by 90 degrees from each other
were respectively assigned to the NiFe (6 nm)/CoFe (1 nm) portion
and CoFe (3 nm)/FeMn (10 nm) portion. FIG. 10 shows the coercive
forces and saturation magnetic fields of the free magnetic layer
and MR ratios in relation to various substrate temperatures. As
shown, the coercive force and saturation magnetic field tended to
slightly increase with the elevation of substrate temperature
although such a tendency was not clearly accounted for. The MR
ratio slowly decreased in accordance with the elevation of the
substrate temperature up to 250.degree. C. but rather sharply fell
at temperatures above 250.degree. C.
[0076] A sample identical in configuration with the above MR effect
element was heated at 270.degree. C. (heat treatment temperature B)
for 5 hours in a magnetic field of 500 Oe parallel to the magnetic
field used to form the CoFe (3 nm)/FeMn (10 nm) portion. FIG. 7
lists the resulting coercive forces and saturation magnetic fields
of the free magnetic layer and MR ratios. As showm, at temperatures
higher than 150.degree. C. inclusive, the coercive force and
saturation magnetic field of the free magnetic layer decreased and
increased, respectively. It will be seen that at temperatures
higher than 150.degree. C. inclusive the rotat ion of the free
magnetic layer in the direction of anisotropy layer and ascribable
tb the Si layer/alumina layer can be reduced. Further, the lower
limit of the substrate temperature capable of reducing the rotation
of the free magnetic layer was higher when the alumina layer was
present than when it was absent; the diffusion of Si from the Si
layer to the Ta/NiFe/CoFe layer is slowed down.
[0077] An MR film with a glass substrate/Si (10 nm)/alumina (10
nm)/Ta (3 nm)/NiFe (6 nm)/CoFe (1 nm)/Cu (2.7 nm) /CoFe (3 nm)/FeMn
(10 nm)/Ta (3 nm) structure was produced. After the formation of
the Si/alumina/Ta/NiFe/CoFe portion, the laminate was heated in a
magnetic field of about 100 Oe identical in direction with the
magnetic field used for film formation. After the sufficient
cooling of the above portion, the 0Cu/CoFe/FeMn/Ta portion was
formed. Magnetic fields different by 90 degrees from each other
were respectively assigned to the NiFe (6 nm)/CoFe (1 nm) portion
and CoFe (3 nm)/FeMn (10 nm) portion. FIG. 11 shows the resulting
coercive forces and saturation magnetic fields of the free magnetic
layer and MR ratios in relation to various heat treatment
temperatures A.
[0078] As shown in FIG. 11, the coercive force and saturation
temperature tended to slightly increase with the elevation of the
heat treatment temperature A although such a tendency was not
clearly accounted for. The MR ratio slowly decreased in accordance
with the elevation of the heat treatment temperature A up to
250.degree. C., but rather sharply fell at temperatures above
150.degree. C.
[0079] A sample having the same structure as the above film was
heated at 270.degree. C. (heat treatment temperature B) for 5 hours
in a magnetic field of 500 Oe paralllel to the magnetic field used
to form the CoFe/FeMn layer. FIG. 12 shows the resulting coercive
forces and saturation magnetic fields of the free magnetic layer of
the sample and MR ratos. As shown, at temperatures higher than
150.degree. C. inclusive, the coercive force and saturation
magnetic field decreased and increased, respectively. It will be
seen that at temperatures above 150.degree. C. the rotation of the
free magnetic layer in the direction of anisotropy and ascribable
to the Si layer/alumina layer can be reduced.
[0080] As also shown in FIG. 11, the lower limit of the heat
treatment temperature A capable of reducing the rotation of the
free magnetic layer was higher when the alumina layer was present
than when it was absent; the diffusion of Si from the Si layer to
the Ta/NiFe/CoFe layer was slowed down.
[0081] An MR effect film with a Cu (2.7 nm)/CoFe (3 nm)/FeMn (10
nm)/Ta (3 nm) structure was produced. Specifically, the
Si/alumina/Ta/NiFe/CoFe portion was formed at a substrate
temperature of 250.degree. C. in a magnetic field of about 100 Oe
and then sufficiently cooled off. Subsequently, the Cu/CoFe/FeMn/Ta
portion was formed. in this case, the heat treatment temperature A
was 250.degree. C. Magnetic fields different by 90 degrees from
each other were respectively assigned to the NiFe (6 nm)/CoFe (1
nm) portion and CoFe (3 nm)/FeMn (10 nm) portion. The coercive
forces and saturation magnetic fields of the free magnetic layer
are listed in FIG. 13 in relation to various thicknesses of the
alumina layer. As shown, the coercive force and saturation magnetic
field of the free magnetic layer and MR ratio are little dependent
on the thickness of the alumina layer.
[0082] A sample identical in structure with the above sample was
heated at 270.degree. C.(heat treatment temperature B) for 5 hours
in a magnetic field of 500 Oe parallel to the magnetic field used
to form the CoFe/FeMn layer. FIG. 14 shows the resulting coercive
forces and saturation magnetic fields of the free magnetic layer
and MR ratios. As shown, the coercive force and saturation magnetic
field increased and decreased, respectively, with an increase in
the thickness of the alumina layer which played the role of a
diffusion control layer. Presumably, the diffusion of Si from the
Si layer to the Ta under layer and to the NiFe/CoFe layer via the
alumina layer was greater in amount when the alumina layer was
thinner, enhancing the thermal stability of the NiFe/CoFe layer as
to induced magnetic anisotropy. The MR ratio decreased with an
increase inthe thickness of the alumina layer. This is presumably
because a thinner alumina layer results in excessive diffusion of
Si to the NiFe/CoFe layer and therefore in a decrease in MR ratio
at the interface between CoFe and Cu.
[0083] An MR element with a glass substrate/Si (10 nm)/diffusion
control layer (10 nm)/Ta (3 nm)/NiFe (6 nm)/CoFe (1 nm)Cu (2.7
nm)/CoFe (3 nm)/FeMn (10 nm)/Ta (3 nm) was produced. Specifically,
the Si/alumina/Ta/NiFe/CoFe portion was formed with the substrate
being heated at 250.degree. C. in a magnetic field of about 100 Oe.
After the sufficient cooling of this portion, the Cu/CoFe/FeMnTa
portion was formed. The heat treatment temperature A was selected
to be 250.degree. C. Magnetic fields different by 90 degrees from
each other were respectively assigned to the NiFe (6 nm)/CoFe (1
nm) portion and CoFe (3 nm)/FeMn (10 nm) portion.
[0084] FIG. 15 shows the resulting coercive forces and saturation
magnetic fields of the free magnetic layer and MR ratios in
relation to various kinds of diffusio i control layers. As shown,
the coercive force and saturation magnetic field of the above
sample remained substantially constant without regard to the kind
of the diffusion control layer.
[0085] A sample identical in structure with the above sample was
heated at 270.degree. C. (heat treatment temperature B) for 5 hours
in a magnetic field parallel to the magnetic field used to form the
CoFe/FeMn layer. FIG. 16 shows the resulting coercive forces and
saturation magnetic fields of the free magnetic layer and MR
ratios. As shown, the coercive force and saturation magnetic field
remain substantially constant without regard to the kind of the
diffusion control layer. This indicates that the anisotropy of the
free magnetic layer was fixed in the direction occurred just after
the film formation, and that the 270.degree. C. (heat treatment
temperature B) 5 hours heat treatment effected in the magnetic
field of 500 Oe did not cause the anisotropy to rotate.
[0086] The above condition is presumably because Si reached the Ta
under layer via the diffusion control layer. However, the MR ratio
was scattered in the range of from 4.9% to 5.2%. This is presumably
because the amount of Si reached the interface between the free
magnetic layer and the nonmagnetic layer was dependent on the kind
of the diffusion control layer.
[0087] An MR effect film with a Ta (3 nm)/NiFe (6 nm)/CoFe (1
nm)/Cu (2.7 nm) /CoFe (3 nm) structure directly formed on a g lass
substrate and an MR effect film with the same structure, but formed
via an Si (10 nm)/alIumina (1 nm) layer, were produced.
Specifically, to form the Ta/NiFe/CoFe layer, the substrate was
heated at 250.degree. C. in a magnetic field of about 100 Oe. After
the sufficient cooling of this layer, the Cu/CoFe/FeMn/Ta layer was
formed. Magnetic fields different by 90 degrees from each other
were respectively applied to the NiFe (6 film)/Co (1 nm) /Cu (2.7
nm) portion and CoFe (3 nm)/FeMn (10 nm) portion. The resulting MR
film was heated at the heat treatment temperature B in a magnetic
field of 500 Oe parallel to the magnetic field used to form the
CoFe/FeMn layer.
[0088] The temperature and duration of heat treatment for fixing
the magnetization of the fixed layer depend on the kind of the
fixing layer. Therefore, as shown in FIGS, 17 and 18, the heat
treatment temperature B and duration thereof were varied in
accordance with the kind of the fixing layer. The heat treatment
may be needless or the heat treatment temperature may be low,
depending on the kind of the fixing layer. However, for both of the
two different configurations, heat treatment was effected at
230.degree. C. for 3 hours or more for the formation of the MR
effect film on a head. The resulting coercive forces and saturation
magnetic fields of the free magnetic layers and MR ratios are shown
in FIGS. 17 and 18.
[0089] As FIG. 17 indicates, the free magnetic layer had a coercive
force greater than 1.5 Oe without regard to the preserce/absence of
the Si/alumina layer. This is presumably because the heat treatment
at the temperature B caused an induced magnetic anisotropy applied
to the free magnetic layer at the time of film formation to bend in
the direction of the magnetic field for heat treatment. As FIG. 18
indicates, as for all of the different kinds of fixing layers, the
coercive force of the free magnetic layer is smaller when the
Si/alumina layer is present than when it is absent. This suggests
that Si was effectively diffused into the NiFe/CoFe layer, As for
some materials including CoCr, the free magnetic layer has a
coercive force as high as 1.8 Oe to 2.4 Oe. This is presumably
ascribable to some cause other than the rotation of the anisotropy,
because the saturation magnetic field of the froe magnetic field is
also high.
[0090] Hereinafter will be described Examples of the present
invention applied to the shield type devices and each effecting
particular heat treatmernt, together with the results of evaluation
as magnetic heads.
EXAMPLE 1
[0091] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/alumina (10 nm)/Ta (3 nm)/Ni.sub.62Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)/Ni.sub.82Fe.sub.18 (1 nm)/Ni.sub.45Mn.sub.54 (30 nm)/Ta (3 nm)
structure. The Ta/NiFe/CoFe layer was formed at the substrate
temperature of 250.degree. C. in a magnetic field of 100 Oe. The
other layers were formed without heating the substrate. After the
formation of the MR effect film, the film was heated at 270.degree.
C. for 5 hours in a magnetic field of 500 Oe perpendicular to the
above magnetic field.
[0092] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt anid
an Mo lower electrode layer were laminated on the MR effect element
in such a manner as to contact the edges of the element. An upper
gap layer and an upper shield layer were implemented by alumina and
NiFe, respectively.
[0093] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data from a CoCrTa recording medium. Therecording medium
had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step for forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0094] As a result of the photoresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0095] The above measurement showed that the mark length halving
the reproduction output was 154 kFIC, that the reproduction output
(peak-to-peak) was 1.7 mV, that an S/N (Signal-to-Noise) ratio was
27 dB, that the error rate was less than 10.sup.-6 inclusive, that
no noise occurred, and that the waveform was desirable. An
environment test effected at 80.degree. C. for 2,500 hours with 500
Oe did not cause the above error rate to change. Further, a current
feed test effected with a current density of 2.times.10.sup.7
A/cm.sup.2 in an environent of 80.degree. C. did not cause the
resistance or the MR ratio to change up to 1,000 hours.
EXAMPLE 2
[0096] A shield type device, having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/alumina (10 nm)/Ta (3 nm) /Ni.sub.62FeA.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2 nm)
/Ni.sub.62Fe.sub.18 (1 nm) /Ni.sub.45Fe.sub.54 (30 nm)/Ta (3 nm)
structure. The Ta/NiFe/CoFe layer was formed at the substrate
temperature of 250.degree. C. in a magnetic field of 100 Oe. The
other layers were formed without heating the substrate. After the
formation of the MR effect film, the film was heated at 25.degree.
C. for 5 hours in a magnetic field of 500 Oe perpendicular to the
above magnetic field.
[0097] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt ard an
Mo lower electrode layer were laminated on the MR film in such e
manner as to contact the edges of the fi m. An upper gap layer and
an upper shield layer were implemented by alumina and NiFe,
respectively.
[0098] The above head was provided with the configuration of FIG.
3. subjected to sl ider machining, and then used to record and
reproduce data from a CoCrTa recording medium. The recording medium
had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, a and a read gap of 0.21 m. As for the write
head, a photoresist curing step for forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0099] As a result of the photoresist curing step, the
ragnetization direction of the fixes layer and that of the fixing
layer expected to be oriented in the directiNr of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0100] The above measurement showed that the mark length ha I ving
the reproduction output was 154 kFCI, that the reproduction output
(peak-to-peak) was 1.8 mV, that an S/N ratio was 26.9 dB, that the
error rate was less than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform ws desirable. An environment test
effected at 80.degree. C. for 2,500 hours with 500 Oe did
notcausethe above error rate to change. Further, a current feed
test effected with a current density of 2.times.10.sup.7 A/cm.sup.2
in an environment of 80.degree. C. did not cause the resistance or
the MR ratio to change up to 1,000 hours.
EXAMPLE 3
[0101] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/alumina (10 nm)/Ta (3 nm)/Ni.sub.82Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)/Ni.sub.82Fe.sub.18 (1 nm)/IR.sub.24Mn.sub.76 (10 nm)/Ta (3 nm)
structure. The Ta/NiFe/CoFe layer was formed at the substrate
temperature of 270.degree. C. in a magnetic field of 100 Oe. The
other layers were formed without heating the substrate. After the
formation of the MR effect film, the film was heated at 250.degree.
C. for 5 hours in a magnetic field of 500 Oe perpendicular to the
above magnetic field.
[0102] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt and an
Mo lower electrode layer were laminated on the MR effect element in
such a manner as to contact the edges of the element. An upper gap
layer and an upper shield layer were implemented by alumina and
NiFe, respectively.
[0103] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data from a CoCrTa recording medium. The recording medium
had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step for farming a coil portion was
effected at 250.degree. C. for 2 hours.
[0104] As a result of the photoresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve. after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of mragnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0105] The above measurement showed that the mark length halving
the reproduction output was 146 KFCI, that the reproduction output
(peak-to-peak) was 1.7 mV, that an S/N ratio was 26.5 dB, that the
error rate was less than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was desirable. An environment test
effected at 80.degree. C. for 2,500 hours with 5 Oe did not cause
the above error rate to change. Further, a current feed test
effected with a current density of 2.times.10.sup.7 A/cm.sup.2 in
an environment of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 1,000 hours.
[0106] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/CiO.sub.2 (10 nm)/Ta (3 nm)/Ni.sub.62Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)/Ni.sub.82Fe.sub.18 (1 nm)/Fe.sub.2O.sub.3(1 nm)/NiO (30 nm)/Ta
(3 nm) structure. In this case, the substrate was not heated at
all. A magnetic field for film formation was selected to be 100 Oe.
After the film formation, the film was heated at 270.degree. C. for
5 hours in a magnetic field of 500 Oe perpendicular to the above
magnetic field.
[0107] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt and an
Mo lower electrode layer were laminated on the MR effect element in
such a manner as to contact the edges of the element An upper gap
layer and an upper shield layer were implewented by alumina and
NiFe. respectively.
[0108] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data from a CoCrTa recording medium. The record ingmedi
um had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step for forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0109] As a result of the photoresi st curing step, the
magnetization direction of the fixed layer Eind that of the fixing
layer expected to be oriented in the d irection of height of the
device rotated and prevented the function of a sipin valve from
being attained. To achieve the function of a spin valve, after the
format ion of the read head portion and write head portion, the
above structure was heated at 20.degree. C. for 1 hour in a
magnetic field of 500 Oe for meignatization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0110] The above measurement showed that the mark length halving
the reproduction output was 160 KFCI, that the reproduction output
(peak-to-peak) was 2.1 mV, that an S/N ratio was 28.5 dB, that the
error rate was less than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was desirable. An environment test
effected at 80.degree. C. for 2,500 hours with 500 Oe did not cause
the above error rate to change. Further, a current feed test
effected with a current density of 2.times.10.sup.7 A/cm.sup.2 in
an environment of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 1,000 hours.
EXAMPLE 6
[0111] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/SiO.sub.2 (10 nm)/Ta (3 nm)/Ni.sub.82Fe.sub.18, (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)Ni.sub.82Fe.sub.18 (1 nm)/CoO (1 nm)/NiO (30 nm)/ Ta (3 nm)
structure. The substrate was not heated at all during film
formation. A magnetic field for film fornmtion was selected to be
100 Oe. After the film formation, the film was heated at
270.degree. C. for 5 hours in a magnetic field of 500 Oe
perpendicular to the above maegnetic field.
[0112] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt and an
Mo lower electrode layer were laminated on the MR effect element in
such a manner as to contact the edgeis of the element. An upper gap
layer and an upper shield layer were implemented by alumina and
NiFe, respectively.
[0113] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data from a CoCrTa recording medium, The recording medium
had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step for forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0114] As a result of the photoresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0115] The above measurement showed that the mark length halving
the reproduction output was 161 kFCI, that the reproduction output
(peak-to-peak) was 2.0 mV, that an S/N ratio was 28.1 dB, that the
error rate was less then 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was desirable. An environment test
effected at 80.degree. C. for 2,500 hours with 500 Oe did not cause
the above error rate to change. Further, a current feed test
effected with a current density of 2.times.10.sup.7 A/cm.sup.2 in
an environment of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 1,000 hours.
EXAMPLE 6
[0116] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/alumina (12 nm)/Ta (3 nm)/Ni.sub.82Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)/Ni.sub.82Fe.sub.18 (1 nm)/Ni.sub.46Mn.sub.54 (30 nm/Ta (3 nm)
structure. The a Ta/NiFe/CoFe layer was formed with the substrate
being heated at 250.degree. C. while the other films were formed
without the substrate being heated. A magnetic field for film
format ion was seI ected to be 100 Oe. After the film formation,
the film was heated at 270.degree. C. for 5 hours in a magnetic
field of 500 Oe perpendicular to the above magnetic field.
[0117] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect ellement. A CoCrPt ard
an Mo lower electrode layer were laminated on the MR effect element
in such a manner as to contact the edges of the element. An upper
gap layer and an upper shield layer were implemented by alumina and
NiFe, respectively.
[0118] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data froma CoCrTa recording medium. The recording medium
had a write track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step far forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0119] As a result of the photoresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axis of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0120] The above measurement showed that the mark length halving
the reproduction output was 157 kFCI. that the reproduction output
(peak-to-peak) was 1.8 mV, that an S/N ratio was 26.9 dB, that the
error rate was less than IVe inclusive, that no noise occurred, and
that the waveform was desirable. An environment test effected at
80.degree. C. for 2,500 hours with 500 Oe did not cause the above
error rate to change. Further, a current feed test effected with a
current dernsity of 2.times.10.sup.7 A/cm.sup.2 in an environment
of 80.degree. C. did not cause the resistance or the MR ratio to
change up to 1,000 hours.
EXAMPLE 7
[0121] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/SiO.sub.2 (10 nm)/Ta (3 nm)/Ni.sub.82Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Co.sub.90Fe.sub.10 (2
nm)/Ni.sub.82Fe.sub.18 (1 nm)/Ni.sub.45Mn.sub.64 (30 nm)/Ta (3 nm)
structure. The Ta/NiFe/CoFe layer was formed with the substrate
being heated at 250.degree. C. while the other films were formed
without the substrate being heated. A magnetic field for film
formation was selected to be 100 Oe. After the film formation, the
film was heated at 270.degree. C. for 5 hours in a magnetic field
of 500 Oe perpendicular to the above magnetic field.
[0122] The MR effect film was patterned in the size of 1 x I p m by
a PR step to produce an MR effect clement. A CoCrPt and an Mo lower
electrode layer were laminated on the MR effect element in such a
manner as to contact the edges of the element- An upier gap layer
and an upper shield layer were implemented by alumina and NiFe,
respectively.
[0123] The above head was provided with the configuration of FIG.
3, subjected to slider machining, and then used to record and
reproduce data from aCoCrTa recordingmedium. The recordingmedium
had awrite to track width of 1.5 m, a write gap of 0.2 m, a read
track width of 1.0 m, and a read gap of 0.21 m. As for the write
head, a photoresist curing step for forming a coil portion was
effected at 250.degree. C. for 2 hours.
[0124] As a resuIt of the photoresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little ratat ion of the easy axisof the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0125] The above measurement showed that the mark length halving
the reproduction output was 159 kFCI, that the reproduction output
(peak-to-peak) was 1.8 mV, that an S/N ratio was 26.8 dB, that the
error-rate was fess than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was desirable. An environiment test
effected at 80.degree. C. for 2,500 hours with 500 Oe did not cause
the above error rate to change. Further, a current feed test
effected with a current density of 2.times.10.sup.7 A/cm.sup.2 in
an environment of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 11,000 hours.
EXAMPLE 8
[0126] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shieId layer and an
alumina lower gap layer. For an MR effect film, use was made of an
Si (10 nm)/tantalum oxide (13 nm)/Ta (3 nm)/Ni.sub.82Fe.sub.18 (4
nm)/Co.sub.90Fe.sub.10 (1 nm)/Cu (2.7 nm)/Ni.sub.82Fe.sub.18 (1
nm)/Ni.sub.48Mn.sub.54 (30 nm)/Ta (3 nm) struture. The Ta/NiFe/CoFe
layer was formed with the substrate being heated at 250.degree. C.
while the other films were formed without the substrate being
heated. A magnetic field for film formation was selected to be 100
Oe. After the film formation, the film was heated at 270.degree. C.
for 5 hours in a magnetic field of 500 Oe perpendicular to the
above magnetic field.
[0127] The MR effect film was patterned in the size of 1.times.1
.mu.m by a PR step to produce an MR effect element. A CoCrPt and an
Mo lower electrode layer were laminated on the MR effect element in
such a manner as to contact the edges of the element, An upper gap
layer hours.
[0128] As a result of the phtotresist curing step, the
magnetization direction of the fixed layer and that of the fixing
layer expected to be oriented in the direction of height of the
device rotated and prevented the function of a spin valve from
being attained. To achieve the function of a spin valve, after the
formation of the read head portion and write head portion, the
above structure was heated at 200.degree. C. for 1 hour in a
magnetic field of 500 Oe for magnetization. The resulting
magnetization curve showed little rotation of the easy axi s of the
free magnetic layer in the direction of magnetization. The
recording medium had a coercive force of 2.5 kOe, and the
reproduction output was measured by varying the length of a record
mark.
[0129] The above measurement showed that the mark length halving
the reproduction output was 156 kFCI, that the reproduction output
(peak-to-peak) was 1.9 mV, that an S/N ratio was 26.7 dB, that the
error rate was less than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was desirable. An environment test
effected at 80.degree. C. for 2,500 hours with 500 Oe did not cause
the above error rate to change. Further, a current feed test
effected with a current density of 2.times.10.sup.7 A/cm.sup.2 in
an environment of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 1,000 hours.
EXAMPLE 11
[0130] A shield type device having the configuration shown in FIG.
1 was produced and included an NiFe lower shield layer and an
alumina mark.
[0131] The above measurement showed that the mark length halving
the reproduction output was 155 kFCI, that the reproduction output
(peak-to-peak) was 1.9 mV, that an S/N ratio was 26.8 dB, that the
error rate was less than 10.sup.-6 inclusive, that no noise
occurred, and that the waveform was dcirable. An environmerit test
effected at 80SC for 2,500 hours with 500 Oe did not cause the
above error rate to change. Further, a current feed test effected
with a current density of 2.times.10.sup.7 Acm.sup.2 in an
envirounmerrt of 80.degree. C. did not cause the resistance or the
MR ratio to change up to 1,000 hours.
[0132] An experimental magnetic disk drive implemented by the
present invention is as fol lows. Three recording media are
amounted on a base included in thediskdrive. Ahead drivecircuit.
asignal processing circuit and an input/output interface are
mounted on the rear of the base. The disk drive is connected to the
cutside by a thirty-two bits bus line.
[0133] A single magnetic heed faces one surface of each recording
medium. A rotary actuator for driving such heads, a circuit for
driving and controlling the roatary actuator, and a spindle motor
for causing the recording media to spin are mounted on the disk
drive. Each recording medium has a diameter of 40 mm and is capable
of rdcording data over Its area tietween the diameter of 10 mm and
the diameter of 40 mm. The disk drive uses a buried servo system
for positioning each head and therefore implements a high
density.
[0134] The above disk drive is directly connectable to a small size
by computer as an outside storage. The input/output interface
includes a cache memory and adapts itself to a bus line whose
transfer rate ranges from 5 megabytes to 20 megabytes per second.
Further, a plurality of such disk drives may be connected together
to constitute a large capacity disk drive if an outside controller
(disc controller) is available.
[0135] In summary, it will be seen that the present invention
provides an MIR effect element including a free magnetic layer
whose coercive force is small, and having an R-H loop involving a
minimum of hysteresis, a method of producing such an MR effect
element, and an MR sensor, an MR sensing system and a magnetic
storage system each using the above MR effect element.
[0136] Various modifications will become possible for those skilled
in the art after receiving the teachings of the present disclosure
without departing from the scope thereof.
* * * * *