U.S. patent application number 15/074071 was filed with the patent office on 2017-09-21 for magnetic head comprising magneto-resistance effect element and side shields.
The applicant listed for this patent is TDK Corporation. Invention is credited to Tetsuya HIRAKI, Takahiko MACHITA, Minoru OTA, Hideyuki UKITA, Hisayoshi WATANABE.
Application Number | 20170270954 15/074071 |
Document ID | / |
Family ID | 59828344 |
Filed Date | 2017-09-21 |
United States Patent
Application |
20170270954 |
Kind Code |
A1 |
HIRAKI; Tetsuya ; et
al. |
September 21, 2017 |
MAGNETIC HEAD COMPRISING MAGNETO-RESISTANCE EFFECT ELEMENT AND SIDE
SHIELDS
Abstract
A magnetic head includes a magneto-resistance effect element in
the form of a multilayer film, a pair of shields between which the
magneto-resistance effect element is interposed in the lamination
direction of the layers of the magneto-resistance effect element
and each functioning as an electrode, a pair of side shields with
one of said side shields on each side of the magneto-resistance
effect element in the direction perpendicular to the lamination
direction of the magneto-resistance effect element interposed
between the pair of shields, the side shields magnetically coupled
to either of the pair of shields, and an anisotropy-application
layer disposed adjacent to the shield magnetically coupled to the
pair of side shields. The pair of shields, the magneto-resistance
effect element, and the pair of side shields are exposed on the air
bearing surface facing a recording medium. The
anisotropy-application layer is not exposed on the air bearing
surface and is provided at a position away from the air bearing
surface.
Inventors: |
HIRAKI; Tetsuya; (Tokyo,
JP) ; OTA; Minoru; (Tokyo, JP) ; WATANABE;
Hisayoshi; (Tokyo, JP) ; MACHITA; Takahiko;
(Tokyo, JP) ; UKITA; Hideyuki; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TDK Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
59828344 |
Appl. No.: |
15/074071 |
Filed: |
March 18, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/3932 20130101;
G11B 5/3912 20130101; G11B 5/39 20130101; G11B 5/3906 20130101 |
International
Class: |
G11B 5/39 20060101
G11B005/39 |
Claims
1. A magnetic head, comprising: a magneto-resistance effect element
in the form of a multilayer film; a pair of shields between which
the magneto-resistance effect element is interposed in the
lamination direction of layers of the magneto-resistance effect
element, each of which functions as an electrode; a pair of side
shields, with one of said side shields on each side of the
magneto-resistance effect element in the direction perpendicular to
the lamination direction of the magneto-resistance effect element
interposed between the pair of shields, the side shields
magnetically coupled to either of the pair of shields; and an
anisotropy-application layer disposed adjacent to the shield
magnetically coupled to the pair of side shields, wherein: the pair
of shields, the magneto-resistance effect element, and the pair of
side shields are exposed on an air bearing surface facing a
recording medium, and the anisotropy-application layer is not
exposed on the air bearing surface and is provided at a position
away from the air bearing surface, a recess part provided in the
insulating layer surrounding the magneto-resistance effect element
and the side shields at a position away from the air bearing
surface, a recess part provided in the shield situated above the
insulating layer in the lamination direction at a position
overlapping with the recess part in the insulating layer in a plan
view, and the anisotropy-application layer is located in the recess
part in the shield.
2. The magnetic head according to claim 1, wherein the
anisotropy-application layer is made of an antiferromagnetic
material.
3-5. (canceled)
6. The magnetic head according to claim 1, wherein the top surface
in the lamination direction of the portion excluding the recess
part of the shield includes the recess part and the top surface in
the lamination direction of the anisotropy-application layer are
situated at the same level.
7. The magnetic head according to claim 1, wherein multiple readers
including the pair of shields, the magneto-resistance effect
element, the pair of side shields, and the anisotropy-application
layer are stacked and separated by an interelement insulating
layer.
8. A head gimbal assembly, comprising a magnetic head slider
including the magnetic head according to claim 1 and a suspension
elastically supporting the magnetic head slider, wherein the
suspension has a flexure to which the magnetic head slider is
joined, a load beam of which one end is connected to the flexure,
and a base plate connected to the other end of the load beam.
9. A magnetic recording device, comprising a magnetic head slider
including the magnetic head according to claim 1, a magnetic
recording medium facing the magnetic head slider, a spindle motor
rotating/driving the magnetic recording medium, and a device
supporting the magnetic head slider and positioning the same with
respect to the magnetic recording medium.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a magnetic head including a
magneto-resistance effect element and side shields used in hard
disc drives (HDD).
[0003] 2. Description of the Related Art
[0004] A magneto-resistance effect element (for example, a TMR
(tunnel magneto-resistance effect) element) used in HDD readers is
configured of a multilayer film in a spin valve structure
consisting of a free layer of which the magnetization direction
changes with respect to the external magnetic field, a pinned layer
of which the magnetization direction is fixed with respect to the
external magnetic field, a spacer layer situated between the free
layer and the pinned layer, a pinning layer for fixing the magnetic
field of the pinned layer, and the like. The magneto-resistance
effect element is interposed between a pair of shields that are
situated on both sides in the lamination direction (down track
direction) of the layers configuring the magneto-resistance effect
element and that also serve as electrodes. The down track direction
is the direction along the magnetic recording tracks of a recording
medium (HD) read by the magneto-resistance effect element. The
direction perpendicular to and crossing the down track direction is
the cross track direction.
[0005] For example, the magnetic head disclosed in U.S. Pat. No.
7,692,901B1 is provided with side shields on both sides of the
magneto-resistance effect element in the direction perpendicular to
the lamination direction (the cross track direction). The side
shields include a soft magnetic substance and also function as bias
magnetic field application layers for aligning the magnetization
direction of the free layer, particularly when no external magnetic
field is applied. The pair of side shields is magnetically coupled
to one of a pair of shields (for example, the upper shield situated
above in the lamination direction). Moreover, an
anisotropy-application layer (for example, an IrMn layer) is
disposed adjacent to the shield magnetically coupled to the side
shields. The anisotropy-application layer imparts exchange
anisotropy to the adjacent shield to magnetize it in a desired
direction (one way in the cross track direction). Then, the pair of
side shields magnetically coupled to this shield is magnetized in
the same direction as the shield. As described above, the free
layer of the magneto-resistance effect element surrounded by the
shield and the side shields magnetized in the same direction has a
magnetization direction aligned in the cross track direction when
no external magnetic field is applied.
[0006] A reader having the above side shields and
anisotropy-application layer has a configuration in which the
magneto-resistance effect element, the pair of shields, and the
anisotropy-application layer are stacked, and therefore has a large
dimension in the down track direction, whereby the read gap is
increased.
[0007] Moreover, in order to improve the area density capacitance
(ADC) in recent HDDs, multi-reader heads having multiple readers
have been developed. US2011/0216432A1 discloses a configuration in
which two independent readers comprising a magneto-resistance
effect element are each interposed between a pair of shields and
are stacked and separated by an insulating layer. When such
multiple readers independent from each other are stacked and
separated by an insulating layer, and each reader consists of a TMR
element or GMR element of the CPP (current perpendicular to plane)
type in which the current flows in the direction perpendicular to
the main surface of the layers, the positional relationship between
the reader situated below and the reader situated above and the
accuracy of width and height of the readers are important, and
precise processing and control is required. Particularly, it is
important to reduce the reader-reader separation (RRS), which
affects the accuracy of reading of adjacent tracks, as much as
possible, which is a major key point to obtain the features of a
multi-reader head. Further, the RRS is the distance in the
lamination direction between the centerlines of the free layers of
the magneto-resistance effect elements of adjacent readers in the
lamination direction.
[0008] In a multi-reader head in which multiple readers are stacked
as described above, it is required to reduce the RSS to, for
example, several tens of nm. As shown in FIGS. 1a and 1b, when a
magneto-resistance effect element V and side shields 2 situated on
both sides of a reader R1 situated below are interposed between a
lower shield S1 and an upper shield S2, and a magneto-resistance
effect element V and side shields 2 situated on both sides of a
reader R2 situated above are interposed between a lower shield S3
and an upper shield S4, the upper shield S2, the lower shield S3,
an inter-element insulating layer 9, and an anisotropy-application
layer 8 (IrMn film) are included between the magneto-resistance
effect element V of the reader R1 and the magneto-resistance effect
element V of the reader V2. If the shields S2 and S3 are
excessively thin in order to reduce the RRS, the SN ratio
problematically drops because the shields S2 and S3 also serve as
the electrodes of the readers R1 and R2. Moreover, there is a limit
on reducing the thickness of the inter-element insulating film 9 in
order to ensure the withstand voltage of the readers R1 and R2.
Thus, there is a need for some other measure to reduce the RRS.
[0009] Throughout this specification, regardless of the orientation
of the magnetic head in use, the lamination direction of the layers
of the magneto-resistance effect element is referred to as the
vertical direction, and one side in the lamination direction is
referred to as "upper" and the other side is referred to as
"lower." As an example, the positional relationship between "upper"
and "lower" is defined so that the pinning layer side of a
magneto-resistance effect element is referred to as "lower" and the
free layer side is referred to as "upper." This lamination
direction is equal to the lamination direction of multiple readers
of a multi-reader head, and generally the reader formed earlier in
the production process of a multi-reader head is "a lower reader"
and the reader stacked and formed later is "an upper reader."
Moreover, the lamination direction is equal to the down track
direction. The terms "upper" and "lower" are used based on the
above definition also with regard to various members other than the
magneto-resistance effect element and readers.
SUMMARY OF THE INVENTION
[0010] The present invention aims to provide a magnetic head
including a magneto-resistance effect element and side shields that
make it possible to reduce the read gap and reduce the RSS when
multiple readers are stacked.
[0011] The magnetic head of the present invention includes a
magneto-resistance effect element in the form of a multilayer film,
a pair of shields between which the magneto-resistance effect
element is interposed in the lamination direction of the layers of
the magneto-resistance effect element and each functioning as an
electrode, a pair of side shields situated on both sides in the
direction perpendicular to the lamination direction of the
magneto-resistance effect element interposed between the pair of
shields and magnetically coupled to either of the pair of shields,
and an anisotropy-application layer disposed adjacent to the shield
magnetically coupled to the pair of side shields. The pair of
shields, the magneto-resistance effect element, and the pair of
side shields are exposed on the air bearing surface facing a
recording medium, and the anisotropy-application layer is not
exposed on the air bearing surface and is provided at a position
away from the air bearing surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1A is a front view showing the ABS of a prior art
magnetic head;
[0013] FIG. 1B is a cross-sectional view perpendicular to the ABS
of the magnetic head shown in FIG. 1A;
[0014] FIG. 2A is a front view showing the ABS of the magnetic head
of the first embodiment of the present invention;
[0015] FIG. 2B is a cross-sectional view perpendicular to the ABS
of the magnetic head shown in FIG. 2A;
[0016] FIG. 3 is an exploded perspective view showing the reader of
the magnetic head shown in FIGS. 2A and 2B;
[0017] FIG. 4 is a cross-sectional view perpendicular to the ABS,
showing an exemplary process of the method of producing the
magnetic head shown in FIGS. 2A and 2B;
[0018] FIG. 5 is a cross-sectional view perpendicular to the ABS,
showing the process following the process shown in FIG. 4;
[0019] FIG. 6 is a cross-sectional view perpendicular to the ABS,
showing the process following the process shown in FIG. 5;
[0020] FIG. 7 is a cross-sectional view perpendicular to the ABS,
showing the process following the process shown in FIG. 6;
[0021] FIG. 8 is a cross-sectional view perpendicular to the ABS,
showing the process following the process shown in FIG. 7;
[0022] FIG. 9 is a cross-sectional view perpendicular to the ABS of
a modified embodiment of the magnetic head of the first embodiment
of the present invention;
[0023] FIG. 10 is a cross-sectional view perpendicular to the ABS
of the magnetic head of the second embodiment of the present
invention;
[0024] FIG. 11 is a cross-sectional view perpendicular to the ABS
of a modified embodiment of the magnetic head of the second
embodiment of the present invention;
[0025] FIG. 12 is a cross-sectional view perpendicular to the ABS
of the magnetic head of the third embodiment of the present
invention;
[0026] FIG. 13 is a cross-sectional view perpendicular to the ABS
of a modified embodiment of the magnetic head of the third
embodiment of the present invention;
[0027] FIG. 14 is a perspective view of the head arm assembly of
the present invention;
[0028] FIG. 15 is a side view of the head stack assembly of the
present invention; and
[0029] FIG. 16 is a plane view of the magnetic recording device of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Embodiments of the magnetic head including a
magneto-resistance effect element and side shields of the present
invention will be described hereafter with reference to the
attached drawings.
First Embodiment
[0031] FIGS. 2A and 2B show the basic structure of the magnetic
head including a magneto-resistance effect element and side shields
of a first embodiment of the present invention. In a magnetic head
1 of the present invention, a magneto-resistance effect element V
configured of a multilayer film of a spin valve structure is
interposed between a pair of shields (a lower shield S1 and an
upper shield S2) in the down track direction to configure a single
reader. As schematically shown in FIG. 3, the magneto-resistance
effect element V primarily has a free layer 3 of which the
magnetization direction changes with respect to the external
magnetic field, a pinned layer 4 of which the magnetization
direction is fixed with respect to the external magnetic field, a
spacer layer 5 situated between the free layer 3 and the pinned
layer 4, and a pinning layer 6 adjacent to the pinned layer 4 and
fixing the magnetic field of the pinned layer 4. The
magneto-resistance effect element V is, for example, a CPP-TMR
element in which the current flows in the direction perpendicular
to the main surfaces of the layers, and the spacer layer 5 is a
tunnel barrier layer. The magneto-resistance effect element V may
include a seed layer situated in the lower part, a cap layer
situated in the upper part, and the like, which are not shown, in
addition to the free layer 3, the pinned layer 4, the spacer layer
5, and the pinning layer 6.
[0032] As shown in FIG. 2A, side shields 2 are provided on both
sides of the magneto-resistance effect element V in the cross track
direction, respectively. The side shields 2 are soft magnetic
material layers and also function as bias magnetic field
application layers. Although not shown, insulating layers may be
provided between the lateral surfaces of the magneto-resistance
effect element V and the side shields 2. The pair of side shields 2
is magnetically coupled to the upper shield S2, respectively. Then,
adjacent to the upper shield S2, an anisotropy-application layer 8
extending in the cross track direction along the upper shield S2 is
provided. The anisotropy-application layer 8 is an
antiferromagnetic layer (for example, an IrMn layer) and magnetized
in the cross track direction. Further, the down track direction is
the direction along the tracks of a recording medium (HD), and the
cross track direction is the direction perpendicular to the down
track direction and crossing the tracks. The portion between the
lower shied S1 and upper shield S2 that excludes and surrounds the
magneto-resistance effect element V and side shields 2 is filled
with an insulating layer 7 consisting of aluminum oxide (for
example, Al.sub.2O.sub.3) or silicon oxide (for example,
SiO.sub.2).
[0033] The lower shield S1 and upper shield S2 are provided so as
to cover the magneto-resistance effect element V of the magnetic
head 1 in a plan view seen from above in the lamination direction
of the layers of the magneto-resistance effect element V. The
magneto-resistance effect element V and the side shields 2 are
provided primarily on and around the air bearing surface ABS of the
magnetic head 1 that faces a recording medium in a plan view seen
from above in the lamination direction. The lower shield S1, the
upper shield S2, the magneto-resistance effect element V, and the
side shields 2 are exposed on the ABS. Further, although not shown,
a protective film covering the ABS may be provided and, in such a
case, the lower shield S1, the upper shield S2, the
magneto-resistance effect element V, and the side shields 2 may
also be covered with the protective film. However, even in such a
case, if the ABS is covered with a protective film, the lower
shield S1, the upper shield S2, the magneto-resistance effect
element V, and the side shields 2 are exposed on the ABS, not
retracted from the ABS in the height direction (the direction
perpendicular to the ABS).
[0034] On the other hand, the anisotropy-application layer 8 is not
exposed on the ABS and is provided at a position retracted from the
ABS in the height direction. It is preferable that the
anisotropy-application layer 8 is retracted by 100 nm or less in
the height direction from the rear end of the free layer 3 (the end
opposite to the ABS) when, for example, the free layer 3 has a
dimension of 30 to 40 nm in the height direction. Moreover, it is
preferable that the anisotropy-application layer 8 is retracted by
30 to 100 nm from the ABS in the height direction. It is preferable
that the anisotropy-application layer 8 is spaced from the ABS at
least so as not to overlap with the magneto-resistance effect
element V in a plan view seen from above in the lamination
direction. The anisotropy-application layer 8 overlaps with the
upper shield S2 at a position away from the ABS, imparts exchange
anisotropy to the upper shield S2, and magnetizes the upper shield
S2 in a desired direction (one way in the cross track direction).
Then, the pair of side shields 2 each magnetically coupled to the
upper shield S2 is magnetized in the same direction. Consequently,
the free layer of the magneto-resistance effect element V
surrounded by the upper shield S2 and the pair of side shields is
magnetized in the same direction as the upper shield S2 and the
pair of side shields 2 when no external magnetic field is
applied.
[0035] A recess part 7a corresponding to the anisotropy-application
layer 8 in shape and dimension is formed in the insulating layer 7
between the lower shield S1 and the upper shield S2 at a position
facing the anisotropy-application layer 8. A recess part S2a
corresponding to the recess part 7a of the insulating layer 7
occurs in the top surface of the upper shield S2 formed to a
substantially uniform thickness on the insulating layer 7. Then,
the anisotropy-application layer 8 is formed so as to fill the
recess part S2a in the top surface of the upper shield S2. Thus,
the increase in thickness due to the anisotropy-application layer 8
at a position retracted from the ABS in the height direction is
offset by the recess part 7a formed in the insulating layer 7. The
overall thickness of the reader R is kept at an equal level to the
configuration in which the anisotropy-application layer 8 is
absent. Therefore, the anisotropy-application layer 8 does not
increase the thickness particularly on the ABS in spite of the
configuration having the side shields 2 and anisotropy-application
layer 8, whereby the read gap can be kept small. Moreover, even if
the anisotropy-application layer 8 is made of IrMn, which is a
relatively corrosive material, the anisotropy-application layer 8
is restrained from eroding since it is not exposed on the ABS. The
thickness of the upper shield S2 is kept nearly uniform even though
the recess part S2a is formed, whereby the electric resistance of
the reader R does not fluctuate. The insulating layer 7 is thinner
in part. However, the insulating layer 7 is a member that has only
to ensure electric insulation, and therefore the change in the
thickness of the insulating layer 7 is unlikely to affect the
function of the reader R.
[0036] The core part of the method of producing the magnetic head 1
will be briefly described. First, as shown in FIG. 4, the lower
shield S1 of the reader R is formed by plating and flattened by
chemical-mechanical polishing (CMP) (Step 101), and the
magneto-resistance effect element V is formed on a part of the
lower shield S1 (Step S102). The magneto-resistance effect element
V includes at least the free layer 3, the pinned layer 4, the
spacer layer 5, and the pinning layer 6 as shown in FIG. 3, and is
formed so as to be exposed on the ABS. As shown in FIG. 5, the side
shields 2 including a soft magnetic substance are formed on both
sides of the magneto-resistance effect element V in the cross track
direction (Step 103). As shown in FIG. 6, the insulating layer 7 is
formed on the portion of the lower shield S1 where the
magneto-resistance effect element V and side shields 2 are absent
so as to surround these elements (Step 104). Then, as shown in FIG.
7, the substantially flat top surface of the insulating layer 7 is
processed by milling or the like to form the recess part 7a (Step
105). The recess part 7a is provided at a position retracted from
the ABS in the height direction. Subsequently, as shown in FIG. 8,
the upper shield S2 is formed on the magneto-resistance effect
element V and the surrounding insulating layer 7 (Step 106). Since
the bottom surface of the upper shield S2 is set in the recess part
7a of the insulating layer 7, the upper shield S2 formed to a
substantially uniform thickness has a step where the recess part 7a
is present and the recess part S2a occurs in the top surface of the
upper shield S2. The upper shield S2 is magnetically coupled to
each of the side shields 2. Then, as shown in FIGS. 2A and 2B, an
IrMn layer that is an antiferromagnetic layer is formed to fill the
recess part S2a in the top surface of the upper shield S2. The IrMn
layer is the anisotropy-application layer 8 adjacent to the upper
shield S2, extending along the upper shield in the cross track
direction, imparting exchange anisotropy to the upper shield S2,
and magnetizing the upper shield S2 in a desired direction (one way
in the cross track direction) (Step 107). Consequently, the pair of
side shields 2 each magnetically coupled to the upper shield S2 is
magnetized in the same direction as the upper shield S2 (the
above-mentioned desired direction). Subsequently, although not
shown, an insulating layer and the like may be formed on the upper
shield S2 and the anisotropy-application layer 8.
[0037] As described above, in the present invention, the upper
shield S2 and the pair of side shields 2 are magnetized in a
desired direction (one way in the cross track direction) using the
anisotropy-application layer 8, whereby the magnetization direction
of the free layer 3 of the magneto-resistance effect element V
surrounded by the upper shield S2 and the pair of side shields 2 is
aligned in the cross track direction when no external magnetic
field is applied. As a result, the accuracy of a reading magnetic
record on an external recording medium is improved. Particularly,
the portion of the upper shield that is not in contact with the
anisotropy-application layer 8 is limited to the ABS and a small
vicinity thereof. The upper shield S2 is mostly in contact with the
anisotropy-application layer 8, and exchange anisotropy is
sufficiently imparted. Therefore, the magnetization of the free
layer 3 of the magneto-resistance effect element S is sufficiently
controlled by the upper shield S2 and the side shields 2 in this
embodiment as well. Additionally, the anisotropy-application layer
8 is absent in the ABS and positioned away from the ABS in this
embodiment. Therefore, the read gap is not increased on the ABS by
the anisotropy-application layer 8 and the entire recording head is
not enlarged, while the magnetization direction is controlled to
improve the accuracy of reading as described above, whereby a high
performance and a compact recording head can be obtained.
[0038] FIG. 9 shows a modified version of the first embodiment. In
this modified embodiment, the anisotropy-application layer 8 is
disposed below the upper shields S2, not above the upper shields
S2. In other words, after the recess part 7a is formed in the
insulating layer 7 as described above, an IrMn film is formed to
fill the recess part 7a and form the anisotropy-application layer
8. The top surface of the anisotropy-application layer 8 in the
lamination direction is formed flush with (at the same level as)
the top surface in the lamination direction of the insulating layer
7 excluding the recess part 7a, and the upper shield S2 is formed
on this surface. The upper shield S2 is formed as a flat layer.
Also in this configuration, the upper shield S2 and the pair of
side shields 2 are magnetized in a desired direction by the
anisotropy-application layer 8, the magnetization direction of the
free layer 3 of the magneto-resistance effect element V is
controlled, and additionally, an increase in the read gap is
prevented.
Second Embodiment
[0039] The first embodiment relates to the magnetic head 1 having a
single reader. The magnetic head 1 of this embodiment is a
multi-reader head 1 in which multiple readers are disposed one on
top of another in the down track direction as shown in FIG. 10.
More specifically, multiple (for example, two) readers R1 and R2
having substantially the same configuration as the reader shown in
FIGS. 2A and 2B are stacked, and an inter-element insulating layer
9 is provided between the vertically adjacent readers R1 and R2.
Moreover, the shields adjacent to the next reader in the vertical
direction, namely the upper shield S2 of the lower reader R1 and
the lower shield S3 of the upper reader R2 are each formed thin. In
each of the multiple readers R1 and R2, the recess part 7a is
formed in the insulating layer 7 as in the first embodiment, recess
parts S2a and S4a occur in the top surface of the upper shields S2
and S4 formed thereon, and the anisotropy-application layers 8 are
formed to fill the recess parts S2a and S4a. In each reader, the
adjacent upper shield S2 or S4 and the side shields 2 magnetically
coupled thereto are each magnetized in a desired direction by the
anisotropy-application layers 8.
[0040] The method of producing the magnetic head of this embodiment
includes, as in the first embodiment, forming the lower shield S1
of the lower reader R1 and forming the magneto-resistance effect
element V, the anisotropy-application layer 8, the side shields 2,
and the insulating layer 7 thereon. Then, the recess part 7a is
formed in the top surfaces of the insulating layer 7 at a position
retracted from the ABS in the height direction. Then, the upper
shield S2 is formed on the magneto-resistance effect element V and
insulating layer 7 so that the recess part 2a occurs in the top
surface of the upper shield S2. The anisotropy-application layer 8
imparting exchange anisotropy to the upper shield S2 is formed to
fill the recess part S2a in the top surface of the upper shield
S2.
[0041] Subsequently, an interelement insulating layer 9 is formed
above the upper shield S2 and anisotropy-application layer 8. The
upper reader R2 is formed on the inter element insulating layer 9
by substantially the same process as described above. In other
words, the lower shield S3, the magneto-resistance effect element
V, the side shields 2, and the insulating layer 7 are formed, and
the recess part 7a is formed in the top surface of the insulating
layer 7 at a position retracted from the ABS in the height
direction. The upper shield S4 is formed on the magneto-resistance
effect element V and the insulating layer 7 so that the recess part
S4a occurs in the top surface of the upper shield S4. The
anisotropy-application layer 8 is formed to fill the recess part
S4a in the top surface of the upper shield S4.
[0042] In this embodiment, as in the first embodiment, each of the
readers R1 and R2 has the side shields 2 and the
anisotropy-application layer 8, whereby the magnetization direction
of the free layer 3 can be aligned when no external magnetic field
is applied, the read gap is kept small, and the RRS that is the
distance between the vertically adjacent readers R1 and R2 is kept
small; thus, high reading performance can be maintained.
[0043] FIG. 11 shows a modified version of this embodiment. In this
modified embodiment, as in the modified embodiment of the first
embodiment shown in FIG. 9, the anisotropy-application layer 8 is
disposed below the upper shields S2 and S4, not above the upper
shields S2 and S4 in each of the readers R1 and R2. In other words,
the anisotropy-application layer 8 is formed to fill the recess
part 7a formed in the insulating layer 7. The upper shields S2 and
S4 are flat layers. Also in this configuration, the magnetization
direction of the free layer 3 of the magneto-resistance effect
element V can be controlled, and additionally, an increase in the
read gap can be prevented in each of the readers R1 and R2.
Third Embodiment
[0044] In the above-described the second embodiment, the
multi-reader head 1 in which two readers R1 and R2 are stacked one
on top of another in the down track direction is described. In this
embodiment, as shown in FIG. 12, three readers R1, R2, and R3 are
stacked on top of another in the down track direction. More
specifically, the three readers R1, R2, and R3 having substantially
the same configuration as the reader shown in FIGS. 2A and 2B are
stacked with the interelement insulating layers 9 in between. The
shields adjacent to the next reader, namely the upper shield S2 of
the lowermost reader R1, the lower shield S3 and upper shield S4 of
the immediately above (middle) reader R2, and the lower shield S5
of the uppermost reader R3 are formed thin. In each of the multiple
readers R1, R2, and R3, the recess parts 7a are formed in the
insulating layers 7 as in the first and second embodiments, recess
parts S2a, S4a, and S6a occur in the upper surface of the upper
shields S2, S4, and S6 formed thereon, and the
anisotropy-application layers 8 are formed to fill the recess parts
S2a, S4a, and S6a. In each of the readers R1, R2, and R3, the
anisotropy-application layers 8 impart exchange anisotropy to the
upper shields S2, S4, and S6. This magnetic head 1 is produced by
repeating the processes of the method of producing the magnetic
head of the first embodiment three times, in other words, by
repeating the processes of forming the upper reader one additional
time after the processes of the method of producing the magnetic
head of the second embodiment. Also in this embodiment,
substantially the same effect as obtained in the first and second
embodiments is obtained.
[0045] Moreover, as a modified version of this embodiment, as shown
in FIG. 13, the anisotropy-application layers 8 can be disposed
below the upper shield S2, S4, and S6, not above the upper shields
S2, S4, and S6 in each of the readers R1, R2, and R3. In this
modified embodiment, as in the modified embodiments of the first
and second embodiments, the anisotropy-application layers 8 are
formed to fill the recess parts 7a formed in the insulating layers
7 and magnetically coupled to the side shields 2 in each of the
readers R1, R2, and R3. The upper side shields S2, S4, and S6 are
flat layers.
[0046] Also in the embodiments shown in FIGS. 12 and 13, the
magnetization direction of the free layer 3 of the
magneto-resistance effect element V can be controlled, and
additionally, an increase in the read gap is prevented in each of
the readers R1, R2, and R3.
[0047] As an application of this embodiment, although not shown,
the present invention can be used in a multi-reader head having
four or more readers. In other words, the anisotropy-application
layer 8 is formed to fill a recess part occurring in the upper
shield of each reader or a recess part formed in the insulating
layer of each reader at a position retracted from the ABS in the
height direction, whereby the RRS between adjacent readers can
individually be reduced.
[0048] Generally, the record reading performance (the reading
accuracy and the like) of the magnetic head 1 is affected by the
read gap and the RRS on the ABS facing the recording medium. In the
present invention, the anisotropy-application layer 8 is absent on
the ABS and therefore does not increase the read gap or RRS on the
ABS. Thus, high reading performance can be maintained. On the other
hand, the upper shield is magnetized in a desired direction (one
way in the cross track direction) by the anisotropy-application
layer 8 situated at a position retracted from the ABS in the height
direction, and the side shields 2 on both sides of the
magneto-resistance effect element V that are magnetically coupled
to the upper shield are magnetized in the same direction. As a
result, the magnetization direction of the free layer 3 of the
magneto-resistance effect element V can efficiently be aligned when
no external magnetic field is applied. The present invention made
these effects compatible for the first time.
[0049] In the above-described embodiments, the
anisotropy-application layer 8 is disposed above or below the upper
shield of a reader along the upper shield. However, the
anisotropy-application layer 8 may be disposed above or below the
lower shield of a reader along the lower shield.
[0050] A head gimbal assembly and HDD using the magnetic head of
the present invention will be described hereafter. A head gimbal
assembly 421 shown in FIG. 14 includes a magnetic head slider 10
including the magnetic head 1 and a suspension 420 elastically
supporting the magnetic head slider 10. The suspension 420 has a
blade spring load beam 422 made of stainless steel, a flexure 423
provided at one end of the load beam 422, and a base plate 424
provided at the other end of the load beam 422. The magnetic head
slider 10 is joined to the flexure 423 and given a proper degree of
freedom by the flexure 423. A gimbal part (not shown) for keeping
the orientation of the magnetic head slider 10 constant is provided
at the portion of the flexure 423 where the magnetic head slider 1
is attached.
[0051] The head gimbal assembly 421 is attached to an arm 430. The
arm 430 moves the magnetic head slider 10 in the cross track
direction CT. The base plate 424 is attached to one end of the arm
430. A coil 431 configuring a part of a voice coil motor is
attached to the other end of the arm 430. A bearing 433 is provided
in a middle part of the arm 430. The arm 430 is rotatably supported
by a shaft 434 attached to the bearing 433. The arm 430 and the
voice coil motor driving the arm 430 configure an actuator.
[0052] FIG. 15 is a side view of a head stack assembly 450. The
head stack assembly 450 has a carriage 451 having multiple arms
430, and the head gimbal assemblies 421 attached to the arms 430.
The head gimbal assemblies 421 are attached to the arms 430 so as
to be arranged in the height direction HT with a space in between.
A pair of permanent magnets 432 is disposed at positions facing
each other via the coil 431 in between.
[0053] FIG. 16 is a plan view of a magnetic recording device (HDD).
The head stack assembly 450 is installed in a magnetic recording
device 460. The magnetic recording device 460 has multiple magnetic
recording media M attached to a spindle motor 461. For each
magnetic recording medium M, two magnetic head sliders 10 are
disposed facing each other across the magnetic recording medium M.
The head stack assembly 450 excluding the magnetic head sliders 10
and the actuator configure a positioning device, supporting the
magnetic head sliders 10 and positioning the magnetic head sliders
10 with respect to the magnetic recording medium M. The magnetic
head sliders 10 are moved in the cross track direction CT of the
magnetic recording medium M and positioned with respect to the
magnetic recording medium M by the actuator. The magnetic head
sliders 10 record information on the magnetic recording medium M by
a magnetic recording element and reproduce information recorded on
the magnetic recording medium M by the reader (the
magneto-resistance effect element) of the magnetic head 1.
[0054] Desirable embodiments of the present invention are presented
and described in detail. However, it should be understood that
various changes and modifications are available to the extent of
not departing from the gist or scope of the attached scope of
claims.
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