U.S. patent application number 12/030788 was filed with the patent office on 2008-05-29 for methods for forming a read sensor.
Invention is credited to Hugo Alberto Emilio Santini.
Application Number | 20080124459 12/030788 |
Document ID | / |
Family ID | 28040643 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080124459 |
Kind Code |
A1 |
Santini; Hugo Alberto
Emilio |
May 29, 2008 |
METHODS FOR FORMING A READ SENSOR
Abstract
A method of making a magnetic head comprises depositing first
and second lead layers in first and second end regions which
surround a central region; and forming a read sensor in the central
region such that a first edge of the read sensor is disposed above
an upper edge of the first lead layer and a second edge of the read
sensor is disposed above an upper edge of the second lead
layer.
Inventors: |
Santini; Hugo Alberto Emilio;
(San Jose, CA) |
Correspondence
Address: |
ZILKA-KOTAB, PC- IBM
P.O. BOX 721120
SAN JOSE
CA
95172-1120
US
|
Family ID: |
28040643 |
Appl. No.: |
12/030788 |
Filed: |
February 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11132689 |
May 18, 2005 |
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12030788 |
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10104612 |
Mar 22, 2002 |
6930864 |
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11132689 |
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Current U.S.
Class: |
427/130 ;
G9B/5.118; G9B/5.124; G9B/5.139 |
Current CPC
Class: |
Y10T 29/49155 20150115;
G11B 5/3163 20130101; G11B 5/3903 20130101; B82Y 10/00 20130101;
G01R 33/093 20130101; G11B 5/398 20130101; G11B 2005/3996 20130101;
G11B 5/332 20130101; G11B 5/3912 20130101; Y10T 29/49041 20150115;
Y10T 29/49032 20150115; Y10T 29/49044 20150115; G11B 5/3116
20130101; G11B 5/3932 20130101; Y10T 29/49046 20150115; Y10T
29/49048 20150115; Y10T 29/49043 20150115; B82Y 25/00 20130101 |
Class at
Publication: |
427/130 |
International
Class: |
B05D 5/00 20060101
B05D005/00 |
Claims
1-9. (canceled)
10. A method of making a magnetic head, comprising: depositing
first and second lead layers in first and second end regions which
surround a central region; and forming a read sensor in the central
region such that a first edge of the read sensor is disposed above
an upper edge of the first lead layer and a second edge of the read
sensor is disposed above an upper edge of the second lead
layer.
11. The method of claim 10, wherein depositing the first and the
second lead layers and forming the read sensor define a track width
for the read sensor.
12. The method of claim 10, wherein forming the read sensor in the
central region further includes forming the read sensor in the
first and the second end regions.
13. The method of claim 10, further comprising: after forming the
read sensor, depositing first and second bias layers in the first
and the second end regions and adjacent the read sensor.
14. The method of claim 10, further comprising: after forming the
read sensor, depositing first and second bias layers in the first
and the second regions and adjacent the read sensor; and depositing
a gap layer over the first and the second bias layers and the read
sensor.
15. The method of claim 10, further comprising: prior to forming
the read sensor, depositing first and second bias layers in the
first and the second end regions over the first and the second lead
layers; and wherein forming the read sensor in the central region
is such that the first edge of the read sensor is disposed above an
edge of the first bias layer and the second edge of the read sensor
is disposed above an edge of the second bias layer.
16. The method of claim 10, wherein forming the read sensor further
comprises: depositing sensor materials in the first and the second
end regions and the central region; forming a lift-off mask in the
central region; and milling the sensor materials using the lift-off
mask such that sensor materials in the first and the second end
regions are removed and sensor materials in the central region
remain.
17. The method of claim 10, further comprising: prior to forming
the read sensor, depositing first and second bias layers in the
first and the second end regions and over the first and the second
lead layers; wherein forming the read sensor further comprises:
depositing sensor materials in the central region and over the
first and the second bias layers in the first and the second end
regions; forming a lift-off mask in the central region; and milling
the sensor materials using the lift-off mask such that sensor
materials in the first and the second end regions are removed and
sensor materials in the central region remain, such that the first
edge of the read sensor is disposed above an edge of the first bias
layer and the second edge of the read sensor is disposed above an
edge of the second bias layer.
18. The method of claim 10, wherein a majority of the read sensor
along a track width thereof lies above a plane extending through
midpoints of the lead layers, the midpoints being positioned midway
between upper and lower extents of the lead layers, the plane being
parallel to planes of deposition of the read sensor and lead
layers.
19. The method of claim 10, wherein the entire read sensor along a
track width thereof lies above a plane extending through midpoints
of the lead layers, the midpoints being positioned midway between
upper and lower extents of the lead layers, the plane being
parallel to planes of deposition of the read sensor and lead
layers.
Description
RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/132,689 filed May 18, 2005, which is
a divisional of U.S. patent application Ser. No. 10/104,612 filed
on Mar. 22, 2002, now U.S. Pat. No. 6,930,864, and which are
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to magnetic heads
and methods of making the same, and more particularly to magnetic
read heads having a magnetic track width that is defined by
underlying bias and lead layers and a sensor profile that is
substantially flat.
[0004] 2. Description of the Related Art
[0005] Higher density recording needs of future direct access
storage devices (DASDs) are forcing the dimensions of magnetic
heads to be well into sub-micron sizes. For example, it is
predicted that for 10 gigabit (Gb) drives, the read head size
should be about 0.5 um; for 20 Gb drives, the read head size should
be about 0.35 um; for 40 Gb drives, the read head size should be
about 0.17 um; and for 100 Gb drives, the read head size should be
about 0.12 um. Such extreme resolutions make patterning techniques
for the magnetic heads very difficult, especially for read
heads.
[0006] One conventional method of fabricating a magnetic head
utilizes a common masking "and milling process. A lift-off mask is
made of two layers, namely, a top photoresist layer and a bottom
underlayer. This bi-layer lift-off mask is formed over the sensor
materials in a central region. Ion milling is performed using the
mask to remove sensor materials in end regions which surround the
central region, such that a central read sensor below the lift-off
mask is formed. Bias layers and lead layers are then deposited in
the end regions and over the mask, and the lift-off mask is removed
by dissolving the bottom underlayer. Finally, a gap layer is
deposited over the read sensor and the surrounding lead layers.
[0007] The above-described technique works very well in defining
sensor structures up to 0.5 um, but shows limitations beyond that
size. The main issue is that the very small active region is
positioned between much thicker bias and lead layers which form
what is known as a contiguous junction. The ion-beam deposited
leads provide a large increase in thickness very close to this
junction, which creates a steep sensor profile. This steep profile
results in poor coverage of the leads by the gap layer (e.g., the
gap layer may crack). Thus, it is preferred that the insulator be
applied over a sensor profile that is less steep.
[0008] Another existing method of fabricating a magnetic head
mitigates the problem of the steep sensor profile. Using this
method, a shield layer which lies underneath the bias and lead
layers is formed with recesses in the end regions within which the
bias and lead layers are deposited. Since the surrounding layers
are sunken into the recesses, the sensor profile is less steep and
the insulator's coverage of the leads is not compromised. Even
another existing method utilizes the lead film, as opposed to the
bias film, to define the magnetic track width (TW) of the read
sensor. This technique is similar to the lift-off mask technique
where the read sensor is formed via ion milling and bias layers are
deposited in the end regions, but in a subsequent lithographic step
the leads are fabricated inside the bias film and separated by a
distance of the preferred TW.
[0009] Although these existing methods resolve some issues with
respect to read head fabrication, what are needed are improved
methods and apparatus for defining the magnetic track width and
forming a substantially flat sensor profile of a magnetic head.
SUMMARY OF THE INVENTION
[0010] A method of making a magnetic head according to one
embodiment comprises forming a shield layer having first and second
recesses in first and second end regions which surround a central
region; depositing first and second lead layers in the first and
the second recesses; and forming a read sensor in the central
region such that a first edge of the read sensor is positioned
above an edge of the first lead layer and a second edge of the read
sensor is positioned above an edge of the second lead layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a fuller understanding of the nature and advantages of
the present invention, as well as the preferred mode of use,
reference should be made to the following detailed description read
in conjunction with the accompanying drawings:
[0012] FIG. 1 is a planar view of an exemplary magnetic disk
drive;
[0013] FIG. 2 is an end view of a slider with a magnetic head of
the disk drive as seen in plane II-II of FIG. 1;
[0014] FIG. 3 is an elevational view of the magnetic disk drive
wherein multiple disks and magnetic heads are employed;
[0015] FIG. 4 is an isometric illustration of an exemplary
suspension system for supporting the slider and magnetic head;
[0016] FIG. 5 is a partial elevation view of the slider and
magnetic head as seen in plane V-V of FIG. 2;
[0017] FIG. 6 is a top view of the second pole piece and coil
layer, a portion of which is shown in FIG. 5, with all insulation
material removed;
[0018] FIG. 7 is a partial ABS view of the slider taken along plane
VII-VII of FIG. 5 to show tile read and write elements of the
magnetic head;
[0019] FIG. 8 is a cross-sectional view of a magnetic head of the
prior art;
[0020] FIG. 9 is an expanded cross-sectional view of the magnetic
head of FIG. 8;
[0021] FIG. 10 is a cross-sectional view of another magnetic head
of the prior art;
[0022] FIG. 11 is a cross-sectional view of one embodiment of a
magnetic head of the present invention;
[0023] FIG. 12 is a cross-sectional view of another embodiment of
the magnetic head;
[0024] FIG. 13 is a cross-sectional view of even another embodiment
of the magnetic head;
[0025] FIG. 14 is a cross-sectional view of yet even another
embodiment of the magnetic head;
[0026] FIG. 15 is a cross-sectional view of another embodiment of
the magnetic head;
[0027] FIG. 16 is a cross-sectional view of even another embodiment
of the magnetic head;
[0028] FIG. 17 is a cross-sectional view of yet even another
embodiment of the magnetic head;
[0029] FIG. 18 is the first of a series of cross-sectional views of
FIGS. 18-29 which relate to a method of making a magnetic head,
which in FIG. 18 shows a shield layer formed with recesses in end
regions;
[0030] FIG. 19 is the same as that shown in FIG. 18, except that
insulator layers are formed over the shield layer in the
recesses;
[0031] FIG. 20 is the same as that shown in FIG. 19, except that a
gap layer is formed over the insulator layers in the end regions
and over the shield layer in the central region;
[0032] FIG. 21 is the same as that shown in FIG. 20, except that a
lift-off mask is formed in the central region;
[0033] FIG. 22 is the same as that shown in FIG. 21, except that
lead layers are deposited in the end regions;
[0034] FIG. 23 is the same as that shown in FIG. 22, except that
bias layers are deposited in the end regions over the lead
layers;
[0035] FIG. 24 is the same as that shown in FIG. 23, except that
the lift-off mask is removed;
[0036] FIG. 25 is the same as that shown in FIG. 24, except that
sensor materials are deposited over the resulting structure;
[0037] FIG. 26 is the same as that shown in FIG. 25, except that
another lift-off mask is formed in the central region;
[0038] FIG. 27 is the same as that shown in FIG. 26, except that
ion milling was performed to form a read sensor in the central
region;
[0039] FIG. 28 is the same as that shown in FIG. 27, except that
bias layers are deposited in the end regions; and
[0040] FIG. 29 is the same as that shown in FIG. 28, except that a
gap layer is deposited over the bias layers in the end regions and
over the read sensor in the central region.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] The following description is the best embodiment presently
contemplated for carrying out the present invention. This
description is made for the purpose of illustrating the general
principles of the present invention and is not meant to limit the
inventive concepts claimed herein.
[0042] Referring now to the drawings, wherein like reference
numerals designate like or similar parts throughout the several
views, as is illustrated in FIGS. 1-3 a magnetic disk drive 30.
Disk drive 30 includes a spindle there that supports and rotates a
magnetic disk 34. Spindle 32 is rotated by a motor 36 that, in
turn, is controlled by a motor controller 38. A horizontal combined
magnetic head 40 for reading and recording is mounted on a slider
42. Slider 42 is supported by a suspension 44 and actuator arm 46.
A plurality of disks, sliders and suspensions may be employed in a
large capacity direct access storage device (DASD), as shown in
FIG. 3. Suspension 44 and actuator arm 46 position slider 42 to
locate magnetic head 40 in a transducing relationship with a
surface of magnetic disk 34. When disk 34 is rotated by motor 36,
slider 42 is supported on a thin (typically, 0.02 micrometer)
cushion of air (or air bearing) between disk 34 and an air bearing
surface (ABS) 48.
[0043] Magnetic head 40 may be employed for writing information to
multiple circular tracks on the surface of disk 34, as well as for
reading information therefrom. Processing circuitry 50 exchanges
signals representing such information with magnetic head 40,
provides motor drive signals, and also provides control signals for
moving slider 42 to various tracks. In FIGS. 1 and 4, slider 42 is
shown mounted to a head gimbal assembly (HGA) 52 that is mounted to
suspension 44. All of the above components are supported on a base
53.
[0044] FIG. 5 is a side cross-sectional elevation view of a merged
read/write head 40 which has a write head portion 54 and a read
head portion 56. Note also the partial ABS view of head 40 in FIG.
7. Read head portion includes a giant magnetoresistive read (GMR)
sensor 58. GMR sensor 58 is sandwiched between first and second gap
layers 60 and 62 that are, in turn, sandwiched between first and
second shield layers 64 and 66. In response to external magnetic
fields, the resistance of GMR sensor 58 changes. A sense current
conducted through the sensor causes these resistance changes to be
manifested as potential changes, which are processed by processing
circuitry 50 (FIG. 3).
[0045] Write head portion 54 of the head includes a coil layer 68
sandwiched between first and second insulation layers 70 and 72. A
third insulation layer 74 may be employed for planarizing the head
to eliminate ripples in the second insulation layer caused by coil
layer 68. The first, second and third insulation layers are
referred to as an "insulation stack". Coil layer 68, and first,
second and third insulation layers 70, 72 and 74, are sandwiched
between first and second pole piece layers 76 and 78. The first and
second pole piece layers 76 and 78 are magnetically coupled at a
back gap 80, and have first and second pole tips 82 and 84 that are
separated by a non-magnetic gap layer 86 at the ABS. As shown in
FIGS. 2 and 4, first and second solder connections 88 and 90
connect leads (not shown) from GMR sensor 58 to leads 96 and 98 on
suspension 44; third and fourth solder connections 100 and 102
connect leads 104 and 106 from coil 68 (see FIG. 6) to leads 108
and 110 on the suspension.
[0046] FIG. 8 is a cross-sectional view of a magnetic head of the
prior art which may be utilized in conventional disk drive 30. This
design may be referred to as the "sunken prefill" design. The
magnetic head in FIG. 8 has a read sensor 802 formed in a central
region 804, which is surrounded by end regions 806 and 808. Read
sensor 802 is formed over a flat surface of a gap layer 810. Bias
layers 812 and 814 are formed in end regions 806 and 808 directly
over gap layer 810 and over the edges of read sensor 802. Lead
layers 816 and 818 are also formed in end regions 806 and 808, but
directly over bias layers 812 and 814 and over the edges of bias
layers 812 that cover the edges of read sensor 802. Lead layers 816
and 818 are generally positioned at a height above read sensor 802.
A gap layer 820 is formed over lead layers 816 and 818 and read
sensor 802. FIG. 9 is an expanded cross-sectional view of this
magnetic head.
[0047] As shown, the magnetic head of FIGS. 8 and 9 has a steep
sensor profile which may result in a poor coverage of lead layers
816 and 820 by gap layer 820, which may result in an electrical
short between the lead and shield layers. Also, although a
prefiller 822 is formed underneath gap layer 820, there are regions
such as a region 824 where possible electrical shorts can occur
between the contiguous junction and the prefill.
[0048] Another prior art magnetic head is shown in FIG. 10. This
design may be referred to as the "sunken lead" design. The magnetic
head of FIG. 10 has a read sensor 1002 formed in a central region
1004 which is surrounded by end regions 1006 and 1008. Read sensor
1002 is generally formed over a shield layer 1010 having recesses
1030 and 1032 in end regions 1006 and 1008. Prefill layers 1012 and
1014 are formed in recesses 1030 and 1032 directly over shield
layer 1010. A gap layer 1016 is formed in end regions 1006 and 1008
directly over insulator layers 1012 and 1014 and in central region
1004 over shield layer 1010. Read sensor 1002 is formed in central
region 1004 upon this gap layer 1016. Bias layers 1018 and 1020 are
formed in recesses 1030 and 1032 directly over gap layer 1016 and
make contact with top edges of read sensor 1002. Lead layers 1022
and 1024 are also formed in recesses 1030 and 1032 but directly
over bias layers 1018 and 1020 and over the sides of read sensor
1002. A gap layer 1026 is formed over lead layers 1022 and 1024 and
read sensor 1002. With this construction, the magnetic head has a
sensor profile that is relatively flat (e.g., compare with the
sensor profile in FIG. 8).
[0049] Referring now to the present invention, FIG. 11 is a
cross-sectional view of a magnetic head in one inventive
embodiment. The magnetic head of FIG. 11 has a read sensor 1102
formed in a central region 1104 which is surrounded by end regions
1106 and 1108. Read sensor 1102 generally receives signals 1129 for
reading data from a recording medium, such as a disk. Read sensor
1102 may be a giant magnetoresistive (GMR) sensor. Bias layers 1124
and 1126 are formed in end regions 1106 and 1108, respectively,
adjacent to read sensor 1102. A gap layer 1128 is disposed directly
over bias layers 1124 and 1126 and read sensor 11102, which form a
sensor profile that is substantially flat (compare with the sensor
profile in FIG. 8). Having a flat sensor profile is advantageous
because it results in a better insulator coverage by gap layer
1128.
[0050] Directly underneath bias layers 1124 and 1126 are another
pair of bias layers 1120 and 1122, respectively. Directly
underneath these bias layers 1120 and 1122 are lead layers 1116 and
1118, respectively. Lead layers 1116 and 1118 are disposed
generally below read sensor 1102 in recesses 1130 and 1132, which
are originally formed by a shield layer 1110. Prefill layers 1112
and 1114 are formed in recesses 1130 and 1132 over shield layer
1110, and a gap layer 1115 is formed in recesses 1130 and 1132 over
prefill layers 1112 and 1114 and over shield layer 1110 in central
region 1104. Lead layers 1116 and 1118 are formed in recesses 1130
and 1132 directly over this gap layer 1115.
[0051] As shown, bias layers 1120 and 1122 have edges which are
disposed directly underneath the edges of read sensor 1102.
Similarly, lead layers 1116 and 1118 have edges which are disposed
directly underneath the edges of bias layers 1120 and 1122 and
underneath read sensor 1102. The positions of these underlying
edges of bias and lead layers 1116, 1118, 1120, and 1122 relative
to the edges of read sensor 1102 define a magnetic track width (TW)
for read sensor 1102. More particularly, the ends of the edges of
bias and lead layers 1116 and 1120 define one side of the magnetic
TW, and the ends of the edges of bias and lead layers 1118 and 1122
define the other side of the magnetic TW.
[0052] Bias layers 1120, 1122, 1124, and 1126 may be made of any
suitable magnetic material, such as cobalt-platinum-chromium; lead
layers 1116 and 1118 may be made of any suitable conductive
material, such as gold, tungsten, rhodium, or tantalum; gap layers
1115 and 1128 may be made of any suitable insulator material, such
as alumina; and shield layer 1110 may be made of any suitable soft
magnetic material, such as Permalloy.
[0053] FIG. 12 is a cross-sectional view of a magnetic head in
another embodiment. The magnetic head of FIG. 12 is the same as
that described in relation to FIG. 11, except that the magnetic
head in FIG. 12 has bias layers 1202 and 1204 that are relatively
short and not formed entirely over end regions 1106 and 1108. Bias
layers 1202 and 1204 are formed underneath the edges of read sensor
1102 and above lead layers 1116 and 1118. The edges of bias and
lead layers 1116, 1118, 1202, and 1204 define the magnetic TW for
read sensor 1102. FIG. 13 is a cross-sectional view of a magnetic
head in a similar alternate embodiment. The magnetic head of FIG.
13 is also the same as that described in relation to FIG. 11,
except that the magnetic head in FIG. 13 has no bias layers or
edges formed underneath read sensor 1102. Here, only the edges of
lead layers 1116 and 1118 define the magnetic TW.
[0054] FIG. 14 is a cross-sectional view of a magnetic head in even
another embodiment. The magnetic head of FIG. 14 is the same as
that described in relation to FIG. 12, except that the magnetic
head in FIG. 14 has gap layer 1115 formed directly over shield
layer 1110 and prefill layers 1112 and 1114 formed in end regions
1106 and 1108 directly over gap layer 1115. FIG. 15 is a
cross-sectional view of a magnetic head in a similar alternate
embodiment. The magnetic head of FIG. 15 is the same as that
described in relation to FIG. 4, except that the magnetic head in
FIG. 15 also has gap layer 1115 formed directly over shield layer
1110 and prefill layers 1112 and 1114 formed in end regions 1106
and 1108 directly over this gap layer 1115. In the heads of FIGS.
14 and 15, extra insulator coverage can be provided continuously up
to the edges of the leads to reduce the possibility of electrical
shorts (see discussion of FIG. 8).
[0055] FIG. 16 is a cross-sectional view of a magnetic head in even
another embodiment. The magnetic head of FIG. 16 is the same as
that described in relation to FIG. 11, except that read sensor 1602
is not only formed in central region 1104 but also in end regions
1106 and 1108 over bias layers 1124 and 1126. Also, additional bias
layers (e.g., bias layers 1124 and 1126 of FIG. 11) are not
necessary for an adequate design. The edges of bias and lead layers
1116, 1118, 1120, and 1122 define the magnetic TW for read sensor
1602. FIG. 17 is a cross-sectional view of a magnetic head in a
similar embodiment. The magnetic head of FIG. 17 is the same as
that described in relation to FIG. 16, except that a different
shield layer 1702 with no recesses in end regions 1106 and 1108 is
utilized. Here, the gap, lead, and bias layers are instead formed
over the flat shield layer 1702. In this embodiment, the magnetic
head does not have a sensor profile that is flat as those described
in relation to FIGS. 11-16, but favorable properties are still
provided.
[0056] An inventive method of forming a magnetic head will now be
described in relation to FIGS. 18-29. In particular, the formation
of the magnetic head of FIG. 11 will be discussed. Beginning with
FIG. 18, a shield layer 2002 is formed over a substrate. Shield
layer 2002 may be made of any suitable soft magnetic material, such
as Permalloy. As shown, shield layer 2002 has recesses 2004 and
2006 formed in end regions 2008 and 2010, respectively, which
surround a central region 2012. Recesses 2004 and 2006 may be
formed in shield layer 2002 using conventional photolithography and
milling techniques. Preferably, the thickness of shield layer 2012
in central region 2012 is about 2 microns.
[0057] In FIG. 19, prefill layers 2102 and 2104 are formed in end
regions 2008 and 2010, respectively, over shield layer 2002. The
top of shield layer 2002 in central region 2012 remains exposed.
These prefill layers 2102 and 2104 are formed by leaving on the
photoresist mask that was used to form recesses 2004 and 2006 in
shield layer 2002, depositing prefill layers 2102 and 2104 over
shield layer 2012 and the photoresist mask, and then removing the
photoresist mask. Prefill layers 2102 and 2104 may be made of any
suitable insulating material, such as alumina. Preferably, the
thickness of each prefill layer 2102 and 2104 is between 200 and
300 Angstroms.
[0058] In FIG. 20, a gap layer 2202 is then deposited over prefill
layers 2102 and 2104 in end regions 2008 and 2010 and over shield
layer 2002 in central region 2012. Gap layer 2202 may be made of
any suitable insulating material, such as tantalum oxide or silicon
dioxide. Preferably, the thickness of this gap layer 2202 is
between about 100 and 400 Angstroms.
[0059] Next, in FIG. 21, a lift-off mask 2302 is formed in central
region 2012 over gap layer 2202. Lift-off mask 2302 may be a
conventional lift-off mask which is formed using well-known
deposition and etching techniques. The lift-off mask may be, for
example, a bi-layer lift-off mask having a top photoresist layer
and a bottom under-layer. For a description of this lift-off mask
and others, see U.S. Pat. No. 6,218,056B1 which is hereby
incorporated be reference herein.
[0060] Next, in FIG. 22, lead layers 2402 and 2406 are deposited in
recesses 2004 and 2006 over gap layer 2202. Lead material 2408 is
also formed over the top of lift-off mask 2302. Lead layers 2402
and 2406 may be made of any suitable conductive material, such as
gold, tungsten, rhodium, or tantalum. Preferably, each lead layer
2402 and 2406 is deposited to a thickness of between 400 and 700
Angstroms.
[0061] In FIG. 23, bias layers 2502 and 2504 may be deposited in
end regions 2008 and 2010, respectively, over lead layers 2402 and
2406, respectively. Bias material 2506 is also formed over the top
of lead material 2408 on lift-off mask 2302. Bias layers 2502 and
2504 may be made of any suitable magnetic material, such as
cobalt-platinum-chromium. Preferably, bias layer 2502 and 2504 is
deposited to a thickness of between 150 and 250 Angstroms.
Alternatively, the step of depositing these bias layers 2502 and
2504 is skipped so that no underlying bias layers exist (e.g., see
FIGS. 13 and 15).
[0062] Lift-off mask 2302 is then removed using a stripper solution
to dissolve the underlayer, and the resulting structure is shown in
FIG. 24. Although lead and bias layers 2402, 2404, 2502, and 2504
are generally formed in end regions 2008 and 2010, thin edges of
these layers are formed on the outskirts of central region 2012.
Also, a small recess is formed in central region 2012.
[0063] Next, in FIG. 25, sensor materials 2702 are deposited over
bias layers 2502 and 2504 in end regions 2008 and 2010 and over gap
layer 2202 in central region 2012. GMR sensor materials 2702 may
include several common materials such as nickel-iron and
cobalt-iron to name a few. As shown in FIG. 26, another lift-off
mask 2802 is formed in central region 2012 over sensor materials
2702. Lift-off mask 2802 may be a conventional bi-layer lift-off
mask as described above.
[0064] In FIG. 27, ion milling is performed such that sensor
materials 2702 in end regions 2008 and 2010 are removed and a read
sensor 2902 in central region 2012 remains. One edge of read sensor
2902 remains over edges of lead and bias layers 2402 and 2502, and
the other edge of read sensor 2902 remains over edges of lead and
bias layers 2404 and 2504. The positions of these edges define a
magnetic track width for read sensor 2902. The magnetic track width
may be defined to be between 0.1 .mu.m and 0.3 .mu.m. To compare,
the physical or mechanical track width of read sensor 2902 may be
between 0.15 um and 0.4 um.
[0065] This ion milling may be continued even after the sensor
materials in end regions 2008 and 2010 are removed, in order to
remove most of bias layers 2502 and 2504 in end regions 2008 and
2010 and expose the top surfaces of lead layers 2402 and 2404. If
this is done, only short bias layers underneath read sensor 2902
will remain (e.g., see FIGS. 12 and 14).
[0066] In FIG. 28, another pair of bias layers 3002 and 3004 is
then deposited over bias layers 2502 and 2504, respectively. Bias
material 3006 is also formed on top of lift-off mask 2802. Bias
layers 3002 and 3004 may be deposited to a thickness between about
150 and 250 Angstroms. Lift-off mask 2802 is then removed using a
stripper solution to dissolve the underlayer.
[0067] Next, in FIG. 29, a gap layer 3102 is deposited over bias
layers 3002 and 3004 in end regions 2008 and 2010 and over read
sensor 2902 in central region 2012.
[0068] Preferably, gap layer 3102 is deposited to a thickness
between 150 and 400 Angstroms. As described, a sensor profile that
is substantially flat is formed so that gap layer 3102 provides a
good insulating coverage. By "substantially flat", it is more
particularly meant that the distance between the lowest valley of
the read sensor and the highest peak of the adjacent bias layers is
no greater than 150 Angstroms.
[0069] Thus, a magnetic head is made of a shield layer having first
and second recesses defined in first and second end regions which
surround a central region. Bias and lead layers are formed in the
first and the second recesses, and a read sensor is formed in the
central region. Advantageously, edges of the bias and lead layers
are formed below edges of the read sensor to thereby define a
magnetic track width for the read sensor. Also, the sensor profile
is substantially flat so that a gap layer over the sensor can
provide a good insulator coverage.
* * * * *