U.S. patent application number 15/357105 was filed with the patent office on 2018-05-24 for write head designs with sandwich trailing shield (sts) for high data rate perpendicular recording.
The applicant listed for this patent is Headway Technologies, Inc.. Invention is credited to Moris Dovek, Jiun-Ting Lee, Ying Liu, Yue Liu, Yuhui Tang, Yiming Wang.
Application Number | 20180144768 15/357105 |
Document ID | / |
Family ID | 62147250 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180144768 |
Kind Code |
A1 |
Liu; Yue ; et al. |
May 24, 2018 |
Write Head Designs with Sandwich Trailing Shield (STS) for High
Data Rate Perpendicular Recording
Abstract
A PMR writer is disclosed with an all wrap around (AWA) shield
design in which one or more of the leading shield, side shields,
and trailing shield (TS) structure (except the hot seed layer) at
the air bearing surface (ABS) are comprised of an alloy having a
damping parameter .alpha. of .gtoreq.0.04 to minimize wide area
track erasure (WATE). The TS structure comprises two outer 8-16 kG
portions on each side of a center stack with a lower write gap, a
middle 19-24 kG (hot seed) layer, and an upper 16-24 kG TS layer
each having a first cross-track width. The hot seed layer, upper
16-24 kG TS layer and an overlying PP3 trailing shield promote
improved area density capability (ADC). A second 16-24 kG TS layer
having a full width at the ABS may be formed on the first 16-24 kG
TS layer.
Inventors: |
Liu; Yue; (Fremont, CA)
; Liu; Ying; (San Jose, CA) ; Tang; Yuhui;
(Milpitas, CA) ; Lee; Jiun-Ting; (Sunnyvale,
CA) ; Dovek; Moris; (San Jose, CA) ; Wang;
Yiming; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Headway Technologies, Inc. |
Milpitas |
CA |
US |
|
|
Family ID: |
62147250 |
Appl. No.: |
15/357105 |
Filed: |
November 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/00826 20130101;
G11B 5/187 20130101; G11B 5/315 20130101; G11B 5/3912 20130101;
G11B 5/3116 20130101; G11B 5/1278 20130101; G11B 5/3163 20130101;
G11B 5/1871 20130101 |
International
Class: |
G11B 5/60 20060101
G11B005/60; G11B 5/127 20060101 G11B005/127 |
Claims
1. A perpendicular magnetic recording (PMR) writer, comprising: (a)
a main pole with a leading side and a trailing side at an air
bearing surface (ABS), and two sides that connect the leading side
and trailing side and are formed equidistant from a center plane
that is orthogonal to the ABS; (b) a gap layer surrounding the main
pole at the ABS and having a write gap with a bottom surface that
contacts the trailing side at a first plane that is orthogonal to
the center plane and ABS, and has a top surface, the write gap has
a first cross-track width between a first side and second side each
having an end at the first plane and formed equidistant from the
center plane; and (c) a trailing shield structure, comprising; (1)
a (hot seed) magnetic layer having a saturation magnetic moment in
a range of 19-24 kiloGauss (kG) adjoining the write gap top
surface, and having the first cross-track width between two sides
that are equidistant from the center plane, the hot seed magnetic
layer extends from the ABS to a backside that is a first height
from the ABS; (2) a first magnetic layer with a saturation magnetic
moment in a range of 16-24 kG and having a first down-track
thickness (t1) at the ABS, and a bottom surface with the first
cross-track width between two sides formed equidistant from the
center plane, and that adjoins a top surface of the hot seed
magnetic layer, and extends to a back side that is at the first
height from the ABS; and (3) a second magnetic layer with a
saturation magnetic moment in a range of 8-16 kG that contacts the
sides of the hot seed magnetic layer, first magnetic layer, and
write gap on each side of the center plane, has a top surface
formed coplanar with a top surface of the first magnetic layer, and
has a bottom surface at the first plane.
2. The PMR writer of claim 1 wherein each of the sides of the first
magnetic layer form an angle with respect to the bottom surface
thereof such that the top surface of the first magnetic layer has a
cross-track width that is essentially equal to or greater than the
first cross-track width.
3. The PMR writer of claim 1 wherein the trailing shield structure
further comprises a PP3 trailing shield with a front side that is
either recessed from the ABS or exposed to ABS, and contacts the
top surface of the first magnetic layer at a second plane formed
parallel to the first plane, and having a back end that contacts a
top surface of a back gap connection at the second plane.
4. The PMR writer of claim 3 wherein the back gap connection is
comprised of a magnetic layer having a saturation magnetic moment
in a range of 16-24 kG that has the first down-track thickness
between a top surface at the second plane and a bottom surface at a
trailing side of the main pole that is aligned orthogonal to the
ABS.
5. The PMR writer of claim 4 wherein the first down-track thickness
is about 1 micron.
6. The PMR writer of claim 1 wherein the first down-track thickness
is about 0.1 to 0.5 micron, and the trailing shield structure
further comprises a second magnetic layer having a saturation
magnetic moment in a range of 16-24 kG, and with a second
down-track thickness (t2) at the ABS where (t1+t2) is about 1
micron, and having a backside at a second height greater than the
first height, the second magnetic layer with a 16-24 kG saturation
magnetic moment contacts the top surface of the first magnetic
layer at a second plane that is orthogonal to the ABS, and has a
cross-track width greater than the first cross-track width.
7. The PMR writer of claim 6 wherein the trailing shield structure
further comprises a PP3 trailing shield with a front side that is
recessed from the ABS, and contacts a top surface of the second
magnetic layer with a 16-24 kG saturation magnetic moment at a
third plane formed parallel to the second plane, and having a back
end that contacts a top surface of a back gap connection at the
third plane.
8. The PMR writer of claim 7 wherein the back gap connection
comprises an upper layer that is made of a magnetic material with a
16-24 kG saturation magnetic moment and having a top surface at the
third plane, and a lower layer made of a magnetic material with a
16-24 kG saturation magnetic moment and having a top surface at the
second plane.
9. The PMR writer of claim 8 wherein a front side of the lower
layer in the back gap connection is a lesser height from the ABS
than a front side of the upper layer in the back gap
connection.
10. The PMR writer of claim 8 wherein one or more of the second
magnetic layer with an 8-16 kG saturation magnetic moment, first
and second magnetic layers in the trailing shield with a 16-24 kG
saturation magnetic moment, back gap connection, and PP3 trailing
shield are made of an alloy having a damping parameter .alpha. of
.gtoreq.0.04 that is one of FeNiM, FeCoM, FeNM, and FeCoNiM where M
is one of Re, Os, Ir, Rh, Ti, Ta, V, Cr, W, Mn, Mo, Cu, Zr, Nb, Hf,
Ru, Pd, Pt, Ag, and Au.
11. The PMR writer of claim 6 wherein the second magnetic layer
with a 16-24 kG saturation magnetic moment is a PP3 trailing shield
layer that extends to a back end which contacts a top surface of a
back gap connection.
12. The PMR writer of claim 10 wherein the gap layer further
comprises a side gap that contacts each side of the main pole, and
a lead gap that contacts the main pole leading side, and wherein
the PMR writer is further comprised of a side shield that adjoins
the side gap on each side of the center plane, and a leading shield
that adjoins the leading gap, each side shield has a top surface
that adjoins the bottom surface of the second magnetic layer with a
8-16 kG saturation magnetic moment at the first plane.
13. The PMR writer of claim 12 wherein the side shields and the
leading shield are comprised of an alloy having a damping parameter
.alpha. of .gtoreq.0.04, and that is one of FeNiM, FeCoM, FeNM, and
FeCoNiM where M is one of Re, Os, Ir, Rh, Ti, Ta, V, Cr, W, Mn, Mo,
Cu, Zr, Nb, Hf, Ru, Pd, Pt, Ag, and Au.
14. A perpendicular magnetic recording (PMR) writer, comprising:
(a) a main pole with a leading side and a trailing side at an air
bearing surface (ABS), and two sides that connect the leading side
and trailing side and are formed equidistant from a center plane
that is orthogonal to the ABS, the leading side adjoins a lead gap
at the ABS and the trailing side adjoins a write gap at the ABS;
(b) a gap layer surrounding the main pole, the gap layer includes
the lead gap, the write gap having a bottom surface at a first
plane at the ABS and a first cross-track width, and a side gap
which contacts one of the main pole sides on each side of the
center plane; and (c) an all wrap around (AWA) shield structure,
comprising: (1) a (hot seed) magnetic layer with a 19-24 kG
saturation magnetic moment adjoining a top surface of the write
gap, and having the first cross-track width between two sides that
are equidistant from the center plane, the hot seed magnetic layer
extends from the ABS to a backside that is a first height from the
ABS; (2) a first magnetic layer with a 16-24 kG saturation magnetic
moment and having a first down-track thickness (t1) at the ABS, and
a bottom surface with the first cross-track width between two sides
formed equidistant from the center plane, and that adjoins a top
surface of the hot seed magnetic layer, and extends to a backside
that is at the first height from the ABS; (3) a second magnetic
layer with an 8-16 kG saturation magnetic moment that contacts the
sides of the hot seed magnetic layer, the first magnetic layer, and
write gap on each side of the center plane, has a top surface
formed coplanar with a top surface of the first magnetic layer, and
has a bottom surface at the first plane; (4) a side shield that
adjoins each side gap, and having a top surface that contacts the
second magnetic layer at the first plane; and (5) a leading shield
that adjoins the leading gap, and contacts a bottom surface of each
side shield.
15. The PMR writer of claim 14 wherein the sides of the first
magnetic layer each form an angle with respect to the bottom
surface thereof such that the top surface of the first magnetic
layer has a cross-track width that is essentially equal to or
greater than the first cross-track width.
16. The PMR writer of claim 14 wherein the PMR writer further
comprises a PP3 trailing shield with a front side that is either
recessed from the ABS or exposed to ABS, and contacts a top surface
of the first magnetic layer at a second plane that is parallel to
the first plane, and having a back end that contacts a top surface
of a back gap connection.
17. The PMR writer of claim 16 wherein the back gap connection is
comprised of a magnetic layer with a 16-24 kG saturation magnetic
moment and has the first down-track thickness between a top surface
at the second plane and a bottom surface at a trailing side of the
main pole that is aligned orthogonal to the ABS.
18. The PMR writer of claim 17 wherein the first down-track
thickness is about 1 micron, and the PP3 trailing shield back end
contacts the top surface of the magnetic layer with a 16-24 kG
saturation magnetic moment in the back gap connection at the second
plane.
19. The PMR writer of claim 14 wherein the first down-track
thickness is about 0.1 to 0.5 micron, and the trailing shield
structure further comprises a second magnetic layer having a 16-24
kG saturation magnetic moment and with a second down-track
thickness (t2) at the ABS where (t1+t2) is about 1 micron, and has
a backside at a second height greater than the first height, the
second magnetic layer with a 16-24 kG saturation magnetic moment
has a cross-track width greater than the first cross-track width,
and contacts the top surface of the first magnetic layer at a
second plane that is orthogonal to the ABS.
20. The PMR writer of claim 19 wherein the trailing shield
structure further comprises a PP3 trailing shield with a front side
that is recessed from the ABS, and contacts a top surface of the
second magnetic layer with a 16-24 kG saturation magnetic moment,
and having a back end that contacts a top surface of a back gap
connection.
21. The PMR writer of claim 20 wherein the back gap connection
comprises an upper layer that is made of a magnetic material with a
16-24 kG saturation magnetic moment and having a top surface that
is at a third plane that includes a top surface of the second
magnetic layer with a 16-24 kG saturation magnetic moment, and a
lower layer made of a magnetic material with a 16-24 kG saturation
magnetic moment and having a top surface at the second plane.
22. The PMR writer of claim 21 wherein a front side of the lower
layer in the back gap connection is a lesser height from the ABS
than a front side of the upper layer in the back gap
connection.
23. The PMR writer of claim 21 wherein one or more of the second
magnetic layer, first and second magnetic layers with a 16-24 kG
saturation magnetic moment in the trailing shield, PP3 trailing
shield, back gap connection, side shields, and leading shield are
comprised of an alloy having a damping parameter .alpha. of
.gtoreq.0.04, and that is one of FeNiM, FeCoM, and FeCoNiM where M
is one of Re, Os, Ir, Rh, Ti, Ta, V, Cr, W, Mn, Mo, Cu, Zr, Nb, Hf,
Ru, Pd, Pt, Ag, and Au, and the M content is about 1 to 15 atomic %
in the alloy.
24. The PMR writer of claim 19 wherein the second magnetic layer
with a 16-24 kG saturation magnetic moment is a PP3 trailing shield
layer that extends to a back end which contacts a top surface of a
back gap connection.
25. The PMR writer of claim 14 wherein the leading shield is part
of a leading magnetic loop that comprises a leading shield
connection (LSC) layer, which is magnetically connected to a
leading side of the leading shield.
26-46. (canceled)
Description
RELATED PATENT APPLICATIONS
[0001] This application is related to the following: U.S. Pat. No.
9,466,319; and Docket # HT16-009, Ser. No. 15/257,341, filing date
9/6/16; assigned to a common assignee and herein incorporated by
reference in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a trailing shield
structure in a perpendicular magnetic recording (PMR) write head
wherein at least one trailing shield layer above a 19-24 kG hot
seed magnetic layer does not have a full width such that an inner
portion of the trailing shield above the hot seed magnetic layer is
a 16-24 kG layer while an outer portion on each side of the 16-24
kG layer and 19-24 kG hot seed magnetic layer has a lower magnetic
saturation (Ms) value of about 8-16 kG in order to promote faster
write response while maintaining an acceptable wide adjacent track
erasure (WATE).
BACKGROUND
[0003] With growing demands for cloud storage and cloud-based
network computing applications, high and ultrahigh data rate
recording becomes important for near-line and high-end disk drive
devices. It is essential to design a PMR writer that can achieve
optimum high data rate performance in both area density capability
(ADC) and side track erasure (STE) capability.
[0004] A PMR write head typically has a main pole layer with a
small surface area at an air bearing surface (ABS), and coils that
conduct a current and generate a magnetic flux in the main pole
layer such that the magnetic flux exits through a write pole tip
and enters a magnetic medium (disk) adjacent to the ABS. Magnetic
flux is used to write a selected number of bits in the magnetic
medium and typically returns to the main pole through a trailing
loop comprised of a trailing shield structure with a front side at
the ABS and a PP3 trailing shield portion that extends over the
write coils and connects to a top surface of the main pole layer
above a back gap magnetic connection.
[0005] For both conventional (CMR) and shingle magnetic recording
(SMR), continuous improvement in storage area density or ADC is
required for a PMR writer in order to deliver or pack higher bits
per inch (BPI) and higher tracks per inch (TPI). An all wrap around
(AWA) shield structure that surrounds the main pole layer in a PMR
write head is desirable in that the trailing shield is responsible
for improving down track field gradient while side shields and a
leading shield improve the cross track field gradient and TPI as
well as adjacent track erasure (ATE) performance.
[0006] Current PMR writers tend to have the trailing shield (TS)
layer in one piece with the same material from center to edge of
the trailing shield structure. As depicted in FIG. 1, PMR head
performance sits on a line where better TS efficiency (ADC) is
typically traded off for better WATE by selecting magnetic
materials with different Ms values. With a high Ms material, the
magnetic path driving main pole and trailing shield gains
efficiency from low reluctance. However, high Ms materials also
lead to more field leakage and worse WATE. Thus, an improved
trailing shield design is needed to escape the tradeoff line and
approach a point A where both high trailing shield efficiency in
terms of improved ADC and clean WATE are realized.
SUMMARY
[0007] One objective of the present disclosure is to provide a
trailing shield structure for a PMR writer that enables a means of
enhancing trailing shield efficiency without compromising WATE.
[0008] Another objective of the present disclosure is to provide a
method of fabricating an AWA shield design with a trailing shield
structure according the first objective that has a production cost
similar to that of current AWA shields.
[0009] According to a first embodiment, these objectives are
achieved with an AWA shield design around a main pole at the ABS.
The AWA shield design includes a trailing shield configuration
wherein a first 16-24 kG trailing shield layer has a bottom surface
contacting a top surface of a hot seed (19-24 kG) layer, and the
bottom surface has the same cross-track width as the hot seed layer
and underlying write gap. Each side of the first 16-24 kG TS layer
adjoins a 8-16 kG trailing shield layer that extends in a
down-track direction from a top surface of each side shield to the
top surface of the trailing shield structure, and extends in a
cross-track direction from the sides of the write gap, hot seed
layer, and first 16-24 kG TS layer to a far side of the trailing
shield structure. In some embodiments, the sides of the first 16-24
kG TS layer are coplanar with the sides of the write gap and hot
seed layer, and are aligned orthogonal to the cross-track
direction. In alternative embodiments, the first 16-24 kG TS layer
sides are tapered such that a top surface of the first 16-24 kG TS
layer has a larger cross-track width than the bottom surface of
said layer. A PP3 trailing shield layer has a front side that is
recessed from the ABS and contacts the top surface of the first
16-24 kG TS layer. The first 16-24 kG TS layer has a thickness of
about 1 micron for optimum thermomechanical properties. Preferably,
both of the hot seed layer and first 16-24 kG TS layer extend a
first height (h1) from the ABS toward a back end of the PMR write
head.
[0010] Magnetic flux is generated by driving coils that are
proximate to main pole leading and trailing surfaces. When writing
one or more bits in a magnetic medium, magnetic flux exits the main
pole tip at the ABS. Magnetic flux in the magnetic medium re-enters
the PMR writer through the trailing shield structure at the ABS and
then passes in a trailing loop through the front end of the PP3
trailing shield to a back end thereof and then to a back gap
connection that adjoins a back portion of the main pole layer. The
PP3 trailing shield may have an arch (dome) shape or a flat top
surface from a down-track cross-sectional view.
[0011] In another embodiment, a second 16-24 kG TS layer having a
full width is formed at the top surfaces of the 8-16 kG TS layer
and the first 16-24 kG TS layer. The first 16-24 kG TS layer
thickness is thinned so that the combined thickness of the 16-24 kG
TS layers is about 1 micron. This embodiment has the second 16-24
kG TS layer extending to height h1, but enables the height of the
hot seed layer and first 16-24 kG TS layer to be substantially
reduced to h2 where h1>h2. A front side of the PP3 trailing
shield is recessed from the ABS and the front end of the PP3
trailing shield contacts a top surface of the second 16-24 kG TS
layer.
[0012] According to a third embodiment, the second 16-24 kG TS
layer in the second embodiment is omitted and the front side of the
PP3 trailing shield is moved to the ABS. The first 16-24 kG TS
layer has a thickness of 0.1 to 0.5 micron and a top surface
thereof adjoins the PP3 trailing shield from the ABS to height
h1.
[0013] In some embodiments, one or more of the 8-16 kG TS layer,
first and second 16-24 kG TS layers, PP3 trailing shield, side
shields, and leading shield are made a high damping magnetic
material with a Gilbert damping constant (.alpha.) substantially
greater than 0.02, and preferably at least 0.04, and more
preferably .gtoreq.0.05. The high damping magnetic material may be
FeNiRe with a Re content between 3 and 15 atomic %. However, other
alloys including but not limited to FeCoRe, FeCoNiRe, FeNiM, FeCoM,
FeNM, and FeCoNiM where M is one of Os, Ir, Rh, Ti, Ta, V, Cr, W,
Mn, Mo, Cu, Zr, Nb, Hf, Ru, Pd, Pt, Ag, and Au may also be employed
as the high damping magnetic material. As a result, WATE is
considerably reduced compared with designs where each of the
trailing shield layers, side shields, and leading shield are made
of conventional CoFe, NiFe, CoFeNi, or CoFeN alloys. The hot seed
layer is preferably comprised of FeCo, FeCoNi, or NiFe.
[0014] According to one method of forming the AWA shield structure,
a leading shield and side shield layer are sequentially formed on a
substrate. An opening with sidewalls is formed in the side shield
layer that exposes a portion of leading shield top surface.
Thereafter, a gap layer is conformally deposited on the sidewalls
and bottom surface of the opening. Next, the main pole layer is
plated to fill the opening, and a first chemical mechanical polish
(CMP) process is performed to form a planar top surface of the main
pole, side gaps, and the side shields at a first plane that is
orthogonal to the ABS and to a center plane that is aligned in a
down-track direction and bisects the main pole. The write gap is
deposited on the first plane, and then a first photoresist layer is
coated and patterned to form sides thereon thereby uncovering outer
portions of the write gap. Thereafter, an etch process is employed
to remove the uncovered write gap portions and form write gap sides
that stop on each side shield at the first plane. An 8-16 kG
trailing shield layer is plated on exposed portions of each side
shield. Then, the photoresist layer is removed and the hot seed
(19-24 kG) layer and first 16-24 kG TS layer are sequentially
plated on the write gap. A second CMP process is performed to form
top surfaces on the 8-16 kG layer and first 16-24 kG TS layer that
are coplanar.
[0015] Modifications of the fabrication sequence are disclosed that
are used to form alternative embodiments described previously. The
overlying layers in the PMR write head are then formed with
conventional processes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a plot showing the trade off between trailing
shield (TS) efficiency and WATE when the magnetic saturation (Ms)
value is varied in the trailing shield.
[0017] FIG. 2 is an ABS view that shows a prior art shield
structure wherein the trailing shield is comprised of a hot seed
layer on the write gap and an overlying trailing shield that
extends from one side of the shield structure to the other
side.
[0018] FIG. 3 is an ABS view of a first embodiment of a trailing
shield (TS) structure according to the present disclosure wherein a
16-24 kG layer is formed only above the hot seed layer while an
8-16 kG layer adjoins the sides of the 16-24 kG layer.
[0019] FIG. 4 shows a modification of the trailing shield structure
in FIG. 3 wherein the sides of the 16-24 kG layer are not
orthogonal with respect to the hot seed layer top surface.
[0020] FIG. 5 and FIG. 6a are ABS views showing a modification of
the trailing shield structure in FIG. 4 and FIG. 3, respectively,
wherein a second 16-24 kG layer having a full width is formed as
the uppermost layer in the trailing shield.
[0021] FIG. 6b is an ABS view showing another embodiment of the
present disclosure wherein the second 16-24 kG layer in FIG. 6a is
part of a PP3 trailing shield.
[0022] FIGS. 7a-7b are down-track cross-sectional views of
embodiments of the shield structure in FIG. 3 or FIG. 4 wherein a
PP3 trailing shield is formed on the 16-24 kG layer and has an arch
shape.
[0023] FIGS. 8a-8c are down-track cross-sectional views of the
shield structure in FIG. 3 or FIG. 4 wherein the PP3 trailing
shield has a flat top surface and the leading loop for magnetic
flux return to the main pole has various embodiments.
[0024] FIG. 9a and FIG. 10 are down-track cross-sectional views of
two embodiments of the shield structure in FIG. 5 or FIG. 6a
wherein a PP3 trailing shield is formed on a 16-24 kG TS layer and
has an arch shape or flat top surface, respectively.
[0025] FIG. 9b is an enlargement of a portion of the shield
structure in FIG. 9a that is proximate to the main pole and
ABS.
[0026] FIG. 11 and FIG. 12 are down-track cross-sectional views of
two embodiments of the shield structure in FIG. 6b wherein a PP3
trailing shield is formed on the 16-24 kG layer at the ABS and has
an arch shape above a 2+2T coil design and 1+1T coil design,
respectively.
[0027] FIGS. 13-14, and FIGS. 16-17 are ABS views showing a
sequence of steps where a 16-24 kG trailing shield layer with less
than a full width is formed on a hot seed layer, and an 8-16 kG TS
layer is formed adjacent to the 16-24 kG TS layer.
[0028] FIG. 15 and FIGS. 18-19 are down-track cross-sectional views
showing a sequence of steps where a 16-24 kG TS layer with less
than a full width is formed on a hot seed layer, and an 8-16 kG TS
layer is formed adjacent to the 16-24 kG TS layer.
[0029] FIGS. 20-21 are ABS views that depict an alternative process
embodiment of the present disclosure wherein the write gap and hot
seed layer are formed with a cross-track width before the 8-16 kG
TS layer is plated.
[0030] FIGS. 22-23 are down-track cross-sectional views depicting a
sequence of steps in an embodiment of the present disclosure
wherein a second 16-24 kG TS layer is formed on a first 16-24 kG TS
layer.
[0031] FIGS. 24-28 are ABS views illustrating the fabrication of an
alternative AWA shield structure wherein outer portions of the side
shield top surface are formed below a plane that includes an inner
portion of the side shield top surface that contacts the write
gap.
DETAILED DESCRIPTION
[0032] The present disclosure relates to a trailing shield (TS)
structure formed above and adjacent to a write gap wherein a center
(inner) portion thereof is made of a stack having a lower hot seed
layer and an upper high Ms (16-24 kG) layer, and an outer portion
is comprised of a low Ms (8-16 kG) material that adjoins the sides
of the write gap, hot seed layer, and upper 16-24 kG layer. A key
feature is that the inner portion of the TS structure has a higher
Ms than the outer portion in order to promote better ADC while
maintaining an acceptable WATE. Moreover, in an AWA shield
embodiment, one or more of the leading shield, sides shields, 8-16
kG TS layer, and 16-24 kG TS layer may be made of a material with a
Gilbert damping constant (.alpha.) of at least 0.04, and preferably
.gtoreq.0.05 in order to minimize WATE while providing improved ADC
for advanced HDD devices. The main pole may have one or both of a
tapered leading side and tapered trailing side. In the drawings,
the y-axis is a cross-track direction, the z-axis is a down-track
direction, and the x-axis is in a direction orthogonal to the ABS
and towards a back end of the PMR writer. The trailing shield
design described herein is compatible with various coil schemes,
and is not limited to a specific write head structure or to a
particular combined read head/write head configuration.
[0033] Referring to FIG. 2, an ABS view of an AWA shield structure
previously disclosed by the inventors in related U.S. Pat. No.
9,466,319 is depicted. We found that when one or more of the
leading shield, side shields, and trailing shield are made of a
high damping material, WATE performance is significantly improved
without adversely affecting ADC. During dynamic magnetic recording,
the high frequency magnetic field generated from the main pole will
excite the dynamic magnetization rotation inside all of the
surrounding shields. The dynamic magnetization rotations will
propagate away from the main pole, and due to complicated domains
in the shields including the trailing shield, the resulting
magnetization wave may trigger localized magnetic charges that will
cause WATE. It is believed that shields made of a high damping
magnetic material will significantly reduce the propagation
distance of the dynamic magnetization rotation wave due to fast
energy dissipation under high damping constant. Hence, localized
magnetic charge generation will be minimized in the shield
structure thereby reducing the WATE.
[0034] Main pole 14 is shown with a trailing side 14t having track
width TW, and the leading side 14b, which contacts lead gap 13 at
the ABS. Trailing and leading sides are connected by two sides 14s
that each adjoin a side gap 15 with a cross-track width d. Center
plane 44-44 bisects the main pole in a down-track direction. Side
shields 12 contact a top surface 11t of leading shield 11, and each
side shield has a top surface 12t at a plane 41-41 that is
orthogonal to the ABS and to the center plane, and includes main
pole trailing side 14t at the ABS. Write gap 16 having thickness a,
and hot seed (19-24 kG) layer 17 are sequentially formed on the
main pole trailing side and each has a cross-track width w. A full
width trailing shield layer 18 made of a 10-19 kG material such as
FeNiRe is formed on a top surface of the hot seed layer and along
the sides of the write gap and hot seed layer. Trailing shield
layer 20 consists of hot seed layer 17 and trailing shield layer
18. A PP3 trailing shield (not shown) is recessed behind the ABS
plane and adjoins a top surface of TS layer 18.
[0035] In related patent application Ser. No. 15/257,341, we
disclosed that a full width 8-16 kG trailing shield layer may be
formed on the hot seed layer, and below a full width 16-24 kG
trailing shield layer to form a trilayer trailing shield structure
thereby improving write speed (reduced rise time) without
significantly impacting WATE.
[0036] Now we have discovered that by further modifying the
aforementioned trilayer trailing shield structure to limit the low
(8-16 kG) Ms trailing shield layer to outer portions of the TS
structure, replacing an inner portion thereof with a 16-24 kG
material, and making the back gap connection (BGC) or top yoke (TY)
layer with a 16-24 kG material, acceptable WATE is maintained while
further improvement in writing response speed and ADC may be
realized. Preferably, the outer 8-16 kG trailing shield layer is
comprised of a high damping material to optimize WATE performance.
Meanwhile, the hot seed layer and 16-24 kG material in the inner
portion and in the PP3 trailing shield provide a low reluctance
magnetic path to drive magnetic flux through the trailing shield
structure more efficiently, especially at high data rates required
in advanced PMR writer designs. Accordingly, ADC is improved.
[0037] Referring to FIG. 3, an ABS view of an AWA shield design
having a trailing shield structure formed according to a first
embodiment of the present disclosure is depicted. The leading
shield 11, side shields 12, lead gap 13, and side gaps 15 are
retained from the process of record (POR) design previously
described with respect to FIG. 2. Furthermore, write gap 16 and hot
seed layer 17 having sides 16s, 17s, respectively are formed on the
main pole trailing side 14t at the ABS as indicated in the POR
design. Note that the write gap and hot seed layer each have a
cross-track width w of about 0.2 to 1 micron that is greater than
the track width TW, and wherein layers 16, 17 are bisected by
center plane 44-44. The leading shield contacts the bottom surface
of the lead gap and adjoins the side shields along plane 43-43
which is aligned parallel to plane 41-41 described previously.
[0038] A key feature of the present disclosure is that the trailing
shield structure above the hot seed layer is limited to a high Ms
(16-24 kG) layer 24 while the trailing shield layer 23 adjoining
the sides of the write gap, hot seed layer, and high Ms TS layer is
a low Ms (8-16 kG) material. In preferred embodiments, the 8-16 kG
magnetic layer 23 is a high damping (HD) magnetic material that is
an Fe rich alloy such as Fe.sub.XNi.sub.100-XM with an x content of
.gtoreq.50 atomic % and where M is a transition metal with a
content between 1 and 15 atomic % in the alloy. In other
embodiments, alloys including but not limited to FeCoM, and FeCoNiM
where M is one of Re, Os, Ir, Rh, Ti, Ta, V, Cr, W, Mn, Mo, Cu, Zr,
Nb, Hf, Ru, Pd, Pt, Ag, and Au with an M content of 1-15 atomic %
may also be employed in the side shields 12, leading shield 11,
8-16 kG TS layer 23, and in 16-24 kG TS layer 24.
[0039] Preferably, the aforementioned HD magnetic material has a
damping parameter .alpha. which is at least 0.04, and more
preferably .gtoreq.0.05, that is substantially greater than a
typical .alpha. value of about 0.02 for commonly used alloys such
as FeCo, FeNi, and FeCoNi in shield structures. As the M content in
the aforementioned alloys increases, .alpha. also becomes larger
but at the expense of decreasing Ms. Thus, M has an upper limit of
about 15 atomic % to prevent the Ms value from dropping below about
8 kG in the side shields, leading shield, and in TS layer 23. M has
a y content of at least 1 atomic % to yield a substantial increase
in .alpha. for a (Fe.sub.XN.sub.100-X).sub.100-YRe.sub.Y HD layer
compared with a Fe.sub.XNi.sub.100-X layer, for example. Moreover,
the HD magnetic material preferably has a coercivity (Hc) less than
50 Oe. In other embodiments, an Hc value .gtoreq.50 Oe may be
acceptable.
[0040] In the exemplary embodiment in FIG. 3, 16-24 kG trailing
shield layer 24 has a top surface 24t1 that is coplanar with the
top surface 23t of each 8-16 kG trailing shield layer 23. The 16-24
kG TS layer has a thickness t of about 1 micron in order to
optimize thermomechanical properties therein, and has sides 24s
that are coplanar with sides 16s, 17s of the write gap and hot seed
layer, respectively. There is an 8-16 kG TS layer 23 on each side
of the center plane 44-44 so that each TS layer 23 extends from an
inner side that coincides with sides 16s, 17s, 24s to a far side at
side 60 or 61 of the trailing shield structure. Each TS layer 23
contacts a top surface 12t of a side shield 12 at plane 41-41. In
other words, each TS layer 23 has a thickness equivalent to the
combined thicknesses (a+b+t) of write gap 16, hot seed layer 17,
and 16-24 kG TS layer 24, respectively.
[0041] In FIG. 4, an alternative embodiment of the present
disclosure is depicted wherein the trailing shield structure from
FIG. 3 is retained except for 16-24 kG TS layer 24 where each side
24s1 is formed at an angle .sigma. that is greater than 0 degrees
but less than 90 degrees with respect to a plane that includes
bottom surface 24b1. As a result, the cross-track width of top
surface 24t1 is greater than cross-track width w of bottom surface
24b1 at the ABS. Both embodiments shown in FIG. 3 and FIG. 4 have a
so-called sandwich trailing shield (STS) configuration.
[0042] Referring to FIG. 7a, a down-track cross-sectional
perspective is shown along plane 44-44 in FIG. 3 or FIG. 4.
According to one embodiment, hot seed layer 17 and 16-24 kG TS
layer 24 each extend a first height h of 300-800 nm from the ABS.
The 16-24 kG TS layer 24 has a backside 24e, and also has a back
portion 24b with front side 24f contacting a main pole trailing
side 14t2 that is aligned orthogonal to the ABS 30-30. Back portion
24b is also known as a back gap connection (BGC) layer or top yoke
layer. Backside 24e and front side 24f are separated by a
dielectric layer 19 which also adjoins a portion of main pole
trailing side 14t2 that is not covered by BGC layer 24b. There is a
driving coil 21a within the dielectric layer and a gap k of
.gtoreq.0.2 micron between the driving coil and front side 24f, and
between the driving coil and backside 24e to enable a higher degree
of reproducibility when fabricating the dielectric gaps with size k
in a manufacturing environment. In embodiments where 16-24 kG TS
layer 24 is made of a conventional magnetic material or a HD 16-24
kG material, BGC 24b is also comprised of the conventional magnetic
material or HD 16-24 kG material.
[0043] The write head including main pole 14 is formed on a
substructure 10 comprised of magnetic layers and dielectric layers
(not shown) as appreciated by those skilled in the art. Above the
substructure is a return path layer (RTP) 11b with a front side,
which is recessed from the ABS 30-30. The RTP is part of an
optional leading loop design where magnetic flux 9c may return from
a magnetic medium and enter the leading shield 11 before proceeding
through a leading shield connection 11a, the RTP, and a leading
loop BGC 11c. Leading shield 11 is shown adjacent to tapered main
pole leading side 14b1 that has a front end at the ABS. A leading
loop is advantageous for a high density recording (HDR) application
as it offers faster write response, better high data rate
capability, and enhanced ATE and WATE margins. Preferably, the
magnetic layers in the leading loop are comprised of a HD 8-16 kG
material with a damping parameter .alpha. of .gtoreq.0.04, or are
made of a conventional 8-16 kG magnetic material.
[0044] There are bucking coils 8 formed within an isolation layer
29 between the RTP 11b and the main pole trailing side 14t2. A
1+1+2T coil scheme is depicted that relates to driving coils 21a,
21b, and bucking coils 8, respectively. However, the present
disclosure also encompasses other coil designs including well known
1+1T, and 2+2T designs.
[0045] Magnetic flux 9a in the main pole exits the main pole tip
14p when writing one or more bits on a magnetic medium (not shown)
and returns to the main pole as magnetic flux 9c through a leading
loop as mentioned previously, and as magnetic flux 9b through a
trailing loop that includes hot seed layer 17, 16-24 kG TS layer
24, PP3 trailing shield 27, and BGC layer 24b. A front side 27f of
the PP3 trailing shield is recessed from the ABS and contacts a top
surface of the 16-24 kG trailing shield layer at plane 45-45 that
is parallel to main pole trailing side 14t2. A back end of the PP3
trailing shield adjoins a top surface of BGC layer 24b at plane
45-45. The PP3 trailing shield may have inner sides 27s that form
an arch shape over dielectric layer 26 which surrounds driving coil
21b above plane 45-45. Protection layer 28 covers a top surface of
the PP3 trailing shield and extends from the ABS to a back end of
the write head. In some embodiments, the PP3 trailing shield may be
comprised of a HD 16-24 kG material with a damping parameter
.alpha. of .gtoreq.0.04. In other embodiments, the PP3 trailing
shield is made of a conventional 16-24 kG magnetic material.
[0046] In FIG. 7b, an enlarged view of the trailing shield
structure that is proximate to the ABS 30-30 in FIG. 7a is
illustrated. Tapered main pole leading side 14b1 has a front end at
the ABS and is separated from leading shield 11 by lead gap 13. Hot
seed layer 17 is comprised of a larger portion 17b that extends
from the ABS to a backside 17e that is coplanar with the 16-24 kG
TS layer backside 24e at height h, and a smaller portion 17a
adjoining a bottom surface of upper portion 17b from the ABS to a
height less than h. Write gap 16 has a down-track thickness a
behind backside 17e and between tapered main pole trailing side
14t1 and hot seed layer bottom side 17b1, and between main pole
trailing side 14t2 and hot seed layer bottom side 17b2 that extends
parallel to main pole trailing side 14t2 and from an end of side
17b1 to height h. Hot seed portion 17a extends a distance of about
30 to 80 nm from the ABS and has a down-track thickness a0. Hot
seed layer bottom side 17b1 forms a taper angle .theta. with plane
42-42 while main pole trailing side 14t1 has a taper angle of
.beta. with plane 42-42 that is orthogonal to the ABS and passes
through write pole tip 14p. In the exemplary embodiment, both
angles .beta. and .theta. are around 25 degrees. However, in other
embodiments, angle .theta. may be 30-70 degrees while .beta. is
maintained at about 25 degrees. The 16-24 kG TS layer 24 has a
bottom side 24b1 with a front end at the ABS, and a second bottom
side 24b2 from an end of bottom side 24b1 to height h where sides
24b1, 24b2 are aligned substantially parallel to hot seed layer
bottom sides 17b1, 17b2, respectively.
[0047] According to another embodiment that represents a
modification of the PP3 trailing shield in FIG. 7a, the down-track
cross-sectional perspective along plane 44-44 in FIG. 3 or FIG. 4
is shown in FIG. 8 where the arch shape in the PP3 trailing shield
is replaced by a flat top surface 27t that is parallel to main pole
trailing side 14t2 and extends from a front side 27f to a back end
27e of the PP3 trailing shield 27-1 above BGC layer 24b. In this
case, the uppermost driving coil 21b, one bucking coil 8, and
dielectric layer 26 are omitted to provide a 1 coil turn (1+1T)
design. There is a driving coil 21a between backside 24e and front
side 24f as in the previous embodiment. Thus, a top surface of BGC
layer 24b contacts a back portion of the PP3 trailing shield at
plane 45-45, and the BGC layer has a bottom surface that adjoins a
portion of main pole trailing side 14t2. Similar to FIG. 7a, BGC
layer 24b has essentially the same thickness t as a front side of
the 16-24 kG TS layer 24 at the ABS 30-30. Front side 27f is
recessed about 50 to 250 nm from the ABS 30-30. The leading loop
structure that includes leading shield 11, leading shield
connection 11a, RTP 11b, and leading BGC 11c is retained from the
previous embodiment. Furthermore, the trailing loop components
including hot seed layer 17, 16-24 kG TS layer 24, and BGC/TY layer
24b are retained from the previous embodiment while PP3 trailing
shield 27-1 replaces the arched PP3 trailing shield 27.
[0048] In the exemplary embodiments described herein, there is a
leading loop for magnetic flux 9c to return from a magnetic medium
to the main pole layer. According to the embodiments depicted in
FIG. 7a and FIG. 8a, the leading loop has a leading shield
connection (LSC) layer 11a exposed at the ABS 30-30. However, the
present disclosure anticipates the leading loop may alternatively
have one of the following three configurations depicted in FIG. 8b,
FIG. 8c, and in a non-DWS (double write shield) design (not
shown).
[0049] As depicted in FIG. 8b, LSC layer 11a is recessed from the
ABS and is connected to leading shield 11 through a leading shield
bridge 11d with a thickness of 0.3-0.5 micron at the ABS. Here, the
LSC layer replaces the RTP in FIG. 8a and adjoins leading BGC 11c
to complete the leading loop. In yet another embodiment shown in
FIG. 8c, the leading BGC 11c may be omitted such that isolation
layer 29 completely separates the main pole 14 and LSC layer 11a.
There is also a non-DWS (double write shield) design that retains
all of the features in FIG. 8b except both of the LSC layer 11a and
leading BGC are omitted from the leading loop. As a result,
magnetic flux 9b in the trailing loop pathway is enhanced compared
with the DWS design in FIGS. 8a-8b. Moreover, there is sufficient
flux 9c retained in the leading shield 11 and leading shield bridge
11d to suppress stray fields in the side shields and leading shield
thereby maintaining ATE at a level similar to that for a DWS
scheme. It is believed that when a majority of the returning
magnetic flux passes through the trailing loop as in the FIG. 8c
and non-DWS embodiment, hot seed layer 17 in trailing loop becomes
more negative to main pole potential. This condition translates to
a better return field at the main pole trailing edge adjoining
write gap 16 during writing. Furthermore, the better return field
is responsible for improving the field gradient, and improved bit
error rate (BER) and ADC are also achieved. In FIGS. 8a-8c, there
is an LSC layer that is magnetically connected to a leading side
11n of the leading shield.
[0050] The present disclosure also anticipates a so-called funnel
trailing shield (FTS) configuration in an AWA shield design as
depicted in FIG. 5. In particular, the thickness t of the 16-24 kG
TS layer 24 in the STS scheme of FIG. 4 is thinned to a thickness
t1 in the range of 0.1 to 0.5 micron while maintaining an angle
.alpha. of 30 to about 90 degrees where sides 24s1 intersect hot
seed layer top surface 17t. In addition, a second 16-24 kG TS layer
25 having thickness t2 is added at top surfaces 24t1 and 23t and
forms a full width trailing shield layer between far sides 60, 61.
Typically, the full width of the trailing shield structure between
the far sides is about 20 to 30 microns. Top surface 25t of the
second 16-24 kG TS layer is preferably parallel to plane 41-41. In
some embodiments, t2 is greater than t1. Preferably, the combined
thickness (t1+t2) equals about 1 micron to provide an acceptable
thermomechanical performance in the trailing shield structure. Note
that the thickness of the 8-16 kG TS layer 23 is reduced in the FTS
configuration compared with the STS scheme. As a result of less
volume in TS layer 23, the FTS embodiment favors better TS
efficiency over the STS scheme, but with a trade off in less
desirable WATE.
[0051] The aforementioned FTS configuration also comprises an
embodiment where sloped sides 24s1 in FIG. 5 are replaced by a
vertical side with thickness t1 in FIG. 6a. All other aspects of
the trailing shield structure are maintained from FIG. 5. Thus,
sides 24s of the 16-24 kG layer 24, hereafter referred to as the
first 16-24 kG TS layer, are coplanar with sides 17s of the hot
seed layer 17 and with sides 16s of the write gap 16. Furthermore,
each of the layers 16, 17, 24 has a cross-track width w as
indicated earlier in the STS embodiment shown in FIG. 3.
[0052] Referring to FIG. 9a, a down-track cross-sectional
perspective is shown along plane 44-44 in FIG. 5 or FIG. 6a.
According to one embodiment, hot seed layer 17 and first 16-24 kG
TS layer 24 each extend to height c of 50-600 nm from the ABS that
is typically less than height h (300-800 nm) in the STS scheme.
Here, the second 16-24 kG TS layer 25 extends to a backside 25e
that is at height h from the ABS 30-30. The first 16-24 kG layer
has a back portion previously described as BGC layer 24b with front
side 24f that contacts a substantial portion of main pole trailing
side 14t2. The second 16-24 kG TS layer also has a back portion
hereafter referred to as BGC layer 25b with a front side 25f and
contacts a top surface of BGC layer 24b at plane 45-45. A key
feature is that front side 24f at height e is closer to the ABS
than front side 25f in order to provide a shorter rise time (faster
write speed) than in the STS configuration shown in FIG. 7a. Top
surfaces of the second 16-24 kG TS layer 25 and BGC layer 25b are
formed at plane 46-46 that is parallel to plane 45-45 and a
down-track distance t2 therefrom. In embodiments where second 16-24
kG TS layer is comprised of a HD material, BGC layer 25b is also
made of the HD material.
[0053] In the FTS configuration depicted in FIG. 9a, the PP3
trailing shield 27 has an arch shape with a recessed front side 27f
that adjoins a top surface of the second 16-24 kG TS layer at side
27s1 that is on plane 46-46. The back end of the PP3 trailing
shield adjoins a top surface 25t2 of BGC layer 25b at side 27s2
also on plane 46-46. Those skilled in the art will appreciate that
BGC layers 24b, 25b form a back gap connection (BGC) between the
PP3 trailing shield and main pole trailing side 14t2. Driving coils
21a, 21b and bucking coils 8 (1+1+2T scheme) are retained from the
STS configuration. In the exemplary embodiment, driving coil 21a is
formed between backside 25e of the second 16-24 kG TS layer and the
front side 25f of BGC layer 25b. There is a dielectric layer 19
between backside 24e and front side 24f and below plane 45-45.
Besides faster write speed, the FTS configuration in FIG. 9a is
expected to have better BER because of a greater down-track
distance between the second 16-24 kG TS layer and main pole
trailing side 14t2 than the write gap thickness a behind end 17e1
in the STS configuration (FIG. 7b). Thus, dielectric layer 19 has a
greater down-track thickness between plane 45-45 and main pole
trailing side 14t2 in the FTS design than the write gap thickness
in the STS configuration. The leading loop is also retained from
the previous embodiment depicted in FIG. 7a. However, other leading
loop schemes shown in FIG. 8b, FIG. 8c, or a non-DWS configuration
may be used, instead.
[0054] In FIG. 9b, an enlarged view of the trailing shield
structure that is proximate to the ABS 30-30 in FIG. 9a is
illustrated. Tapered main pole leading side 14b1 has a front end at
the ABS and is separated from leading shield 11 by lead gap 13. Hot
seed layer 17 with upper portion 17b and lower portion 17a was
previously described in the first embodiment. Backside 17e on upper
portion 17b is coplanar with first 16-24 kG TS layer backside 24e
at height c that is less than height h of the second 16-24 kG TS
layer backside 25e. Write gap 16 (behind lower portion 17a) may
have a uniform down-track thickness a between tapered main pole
trailing side 14t1 and the hot seed layer at the ABS and up to
height c when top side 17t has the same taper angle as main pole
trailing side 14t1. As explained earlier, top and bottom surfaces
of upper portion 17b may have a greater taper angle .theta. than
taper angle .beta. of trailing side 14t1. The first 16-24 kG TS
layer 24 has a trailing side 24t1 that is at plane 45-45 and with a
front side at the ABS.
[0055] Referring to FIG. 10, an alternative FTS configuration is
shown wherein the PP3 trailing shield 27 in FIG. 9a is replaced by
PP3 trailing shield 27-1 with a flat top surface 27t described
previously. Furthermore, a 1+1T coil scheme may be implemented as
explained earlier with regard to FIG. 8. Top surface 27t is
typically parallel to plane 46-46. PP3 trailing shield front side
27f is recessed from the ABS 30-30 and contacts a top surface of
the second 16-24 kG TS layer 25 at side 27s1 on plane 46-46. The
PP3 trailing shield adjoins BGC layer 25b at plane 46-46. All other
aspects of the trailing shield structure comprising hot seed
portions 17a, 17b, and TS layers 24, 25 in the first FTS
configuration in FIGS. 9a-9b are retained in FIG. 10.
[0056] In a second embodiment of the FTS configuration shown in
FIG. 11, the FTS scheme in FIG. 9a is modified by omitting the
second 16-24 kG TS layer and by moving the PP3 trailing shield
front side 27f to the ABS 30-30. Moreover, the backsides 17e, 24e
of the hot seed layer 17 and first 16-24 kG TS layer 24,
respectively, are moved back to height h. Note that a front portion
of PP3 trailing shield 27 has a backside 27c at height h from front
side 27f such that backside 27c is coplanar with backside 24e. The
first 16-24 kG TS layer has a thickness t1 that is preferably 0.1
to 0.5 micron at the ABS while the PP3 trailing shield has a
thickness t3 at the ABS where the combined thickness (t1+t3) equals
about 1 micron. In the exemplary embodiment, BGC layer 24b also has
a thickness t1. By moving front side 24f closer to the ABS than in
the STS embodiment shown in FIG. 3, write speed is enhanced. To
accommodate the short dielectric gap n in dielectric layer 19
between front side 24f and backside 24e, driving coil 21a is
shifted above plane 45-45 so that both coils 21a, 21b are an equal
down-track distance from main pole trailing side 14t2 and form a
2+2T coil scheme with bucking coils 8. Driving coils 21a, 21b are
separated by dielectric layer 26 that is above plane 45-45 and
between backside 27c and inner side 27s. Thus, a front portion of
PP3 trailing shield 27 contacts 16-24 kG TS layer 24 at the ABS,
and a back portion of the PP3 trailing shield adjoins BGC layer 24b
at plane 45-45. An enlarged view of the region around write pole
tip 14p is not shown but is essentially the same as illustrated for
the STS embodiment in FIG. 7b where the hot seed layer has an upper
portion 17b and lower portion 17a.
[0057] Referring to FIG. 12, another FTS configuration is depicted
wherein the FTS scheme from FIG. 11 is retained except for the PP3
trailing shield with an arch (dome) shape. Although a 1+1T coil
design is depicted with a single driving coil 21a between back side
27c and a back end 27e above BGC layer 24b at plane 45-45, other
coil schemes may be incorporated in the write head as indicated
earlier. Gap n in dielectric layer 19 between backside 24e and
front side 24f is maintained from the previous embodiment. However,
inner side 27s is shifted closer to the ABS so that the volume of
dielectric layer 26 between PP3 trailing shield 27-2 and plane
45-45 is reduced. It should be understood that other leading loop
schemes may be employed in the FIG. 11 and FIG. 12 embodiments. For
example, the leading loop design depicted in FIG. 8b or FIG. 8c, or
a non-DWS configuration that was previously described may be
selected.
[0058] The present disclosure also encompasses a method of forming
a PMR writer having an AWA shield design disclosed herein as
depicted in FIGS. 13-19 that relate to process steps from leading
shield formation to trailing shield deposition. The remainder of
the fabrication sequence before leading shield formation and after
trailing shield deposition comprises conventional steps that are
well known in the art and are not described herein.
[0059] Referring to FIG. 13, a side shield layer 12 is plated on a
leading shield 11. Then a photoresist layer 60 is coated on the
side shield and is patterned by a photolithography method to form
an opening 70 with sides 60s therein corresponding to the desired
shape of the main pole layer. The opening is transferred through
the side shield layer by a standard ion beam etching (IBE) or
reactive ion etching (RIE) process and stops on top surface 11t of
the leading shield at plane 43-43. The opening is formed between
sides 12s and has a bottom surface at leading shield top surface
11t. In the exemplary embodiment, sides 12s are not orthogonal to
plane 43-43 so that the cross-track distance between sides 60s is
greater than the cross-track width of the exposed portion of top
surface 11t.
[0060] Referring to FIG. 14, a gap layer is preferably conformally
deposited with a thickness of about 20 to 50 nm on the exposed
portion of top surface 11t, and sides 12s, to partially fill the
opening 70. The gap layer becomes the leading gap and side gap
layers after subsequent processing. It should be understood that
the gap layer may be a stack of layers including a lower alumina
layer contacting sides 12s and top surface 11t, and an upper Ru
layer or another metal layer disposed on the alumina layer. Next,
the main pole including write pole tip 14 at the ABS is
electroplated to fill opening 70, and a chemical mechanical polish
(CMP) process is employed to remove photoresist layer 60 and any
material above plane 41-41. The CMP process forms top surface 12t
of side shield layers 12 that is coplanar with main pole trailing
side 14t at plane 41-41. Side portions of the gap layer become side
gaps 15, and a bottom portion is now shown as leading gap 13. In
some embodiments, ion milling may be used at this point to form a
taper on the main pole trailing side by a process sequence well
known to those skilled in the art.
[0061] Referring to FIG. 15 with a down-track cross-sectional view
along plane 44-44 in FIG. 14, dielectric layer 19 is deposited on
the tapered main pole trailing side 14t1, and on a main pole
trailing side 14t2 that remains orthogonal to the eventual ABS
hereafter referred to as plane 30-30. It should be understood that
the ABS is formed by a lapping process after all layers in the
write head are laid down at a back end of the fabrication sequence.
Then, a second photoresist layer 66 is coated on the dielectric
layer and is patterned by a conventional method to form opening 71
between plane 30-30 and front side 66f of the second photoresist
layer. In one embodiment that involves fabrication of the FTS
configuration in FIG. 9a or FIG. 10, the height of the opening is
c. In other embodiments comprising the fabrication of STS
configurations in FIG. 7a and FIG. 8, or the FTS configurations in
FIGS. 11-12, the opening may extend over the main pole trailing
side 14t2 to height h. Next, a RIE or IBE process is performed to
transfer opening 71 through the dielectric layer and stop on
trailing side 14t1 for embodiments with height c, or ending on
trailing sides 14t1, 14t2 when height h is desired. Corner 14n is
the point where the two main pole trailing sides intersect.
[0062] With regard to FIG. 16, the write gap 16 is deposited on a
substrate comprised of top surfaces 12t, and 14t1 in opening 71
with height c, or alternatively on surfaces 12t, 14t1, 14t2 in an
opening with height h (not shown). Thereafter, a third photoresist
layer is coated on the write gap and is patterned with a
photolithography method to form photoresist island 80 with sides
80s that are separated by cross-track width w at the eventual ABS.
Then, an IBE or RIE step is employed to transfer the shape of the
third photoresist layer through the write gap to generate sides 16s
that are essentially coplanar with sides 80s and substantially
orthogonal to top surface 12t at the ABS. The IBE or RIE step
exposes portions of top surface 12t on each side of center plane
44-44. Unlike the process of record where the write gap and hot
seed layer are simultaneously etched to form cross-track width w in
FIG. 2, this embodiment avoids hot seed layer etching and thereby
substantially reduces undesirable etching into top surface 12t at
plane 41-41.
[0063] The partially formed AWA shield structure in FIG. 16 is
shown in FIG. 17 after the 8-16 kG trailing shield (TS) layer 23 is
plated on uncovered portions of side shields 12 and adjoins sides
16s. A far side of each 8-16 kG TS layer coincides with a far side
60 or 61 of the trailing shield structure. The third photoresist
layer is stripped to leave an opening 71a above write gap trailing
side 16t and between inner sides 23s of 8-16 kG TS layers 23.
[0064] Referring to FIG. 18, a RIE or IBE process is used to form
the desired shape of hot seed lower portion 17a in the write gap 16
at the ABS. Furthermore, the aforementioned etch may include an
angled etch to form a larger taper angle on the write gap layer top
surface (corresponding to angle .theta. in FIG. 7b). Thus, the
taper angle .theta. may be enlarged from approximately 25 degrees
to a value that is within the range of 30-70 degrees. Next, the hot
seed layer comprised of lower portion 17a and upper portion 17b is
plated in opening 71a. In the following step, another photoresist
layer 82 is coated on dielectric layer 19 and on the hot seed
layer. The photoresist layer is patterned to form opening 72 behind
backside 82e that is at height m from plane 30-30. An etch process
is employed to transfer the opening through the dielectric layer
and stops on main pole trailing side 14t2 thereby forming backside
19e on the dielectric layer.
[0065] Referring to FIG. 19, the patterned photoresist layer 82 is
stripped by a conventional method. Next, a 16-24 kG layer is plated
on hot seed layer 17 to form 16-24 kG TS layer 24, and on exposed
portions of main pole trailing side 14t2 to form BGC layer 24b. A
CMP process is performed to form top surface 24t1 on 16-24 kG TS
layer 24, top surface 19t on the dielectric layer, and top surface
24t2 on BGC layer 24b. All of the aforementioned top surfaces are
formed at plane 45-45. Note that backside 24e coincides with front
side 19f (shown in FIG. 15), and front side 24f coincides with
backside 19e of dielectric layer 19 in FIG. 18. In the exemplary
embodiment, the CMP process stops to provide a thickness t of about
1 micron in dielectric layer 19, BGC layer 24b, and in 16-24 kG TS
layer 24 at the ABS. However, in other embodiments involving the
fabrication of FTS configurations, the CMP process may be
lengthened so that the thickness of the aforementioned layers is
further reduced to t1 in the range of 0.1 to 0.5 micron.
[0066] Subsequently, driving coil 21 is formed in dielectric layer
19, and the PP3 trailing shield 27 is plated on the top surfaces of
the 16-24 kG TS layer proximate to the ABS, and on the BGC layer
24b to form the STS configuration shown in FIG. 7a and FIG. 8a.
[0067] In an alternative FTS embodiment where front side of the BGC
layer 24b is moved closer to the ABS, dielectric layer 26 is formed
on top surfaces of the 16-24 kG TS layer and BGC layer 24b, and
then driving coils 21a, 21b or only driving coil 21a is formed in
dielectric layer 26 prior to plating PP3 trailing shield 27, or
27-2, with a front side at the ABS 30-30, respectively, as
previously described with regard to trailing shield structures
shown in FIG. 11 and FIG. 12.
[0068] In another embodiment, the fabrication process flow
represented by FIGS. 13-19 may be followed through formation of
opening 71 in FIG. 15. Then, as shown in FIG. 20, the write gap 16
and hot seed layer 17 may be sequentially deposited at plane 41-41
before photoresist layer 81 is coated and patterned to generate the
photoresist mask with sides 81s. A RIE or IBE process is employed
to form sides 16s, 17s on the write gap and hot seed layer,
respectively.
[0069] In the next step shown in FIG. 21, 8-16 kG TS layer 23 is
plated on exposed surfaces of side shield layers 12 at plane 41-41.
The photoresist layer is removed to leave a top surface 17t of the
hot seed layer exposed within opening 71b.
[0070] At this point, the process steps shown in FIG. 18 and FIG.
19 are performed to yield the STS trailing shield configurations
described earlier with respect to FIG. 7a and FIG. 8, or the FTS TS
configurations depicted in FIG. 11 and FIG. 12.
[0071] In order to manufacture the FTS trailing shield
configurations illustrated in FIG. 9a and FIG. 10, the process flow
continues from FIG. 19 in the previous paragraph with the process
steps shown in FIG. 22 and FIG. 23.
[0072] Referring to FIG. 22, the second dielectric layer 22 is
deposited on top surface 19t of the dielectric layer 19, top
surface 24t1 of the 16-24 kG TS layer 24, and on top surface 24t2
of BGC layer 24b with thickness t1. A photoresist layer 83 is
coated on the second dielectric layer and patterned to form opening
73 with height h at the ABS above top surface 24t1, and opening 74
above top surface 24t2. A backside 22e of the second dielectric
layer is a greater distance from the ABS 30-30 than front side 24f
of BGC layer 24b. A RIE or IBE process is then performed to
transfer opening 73 and opening 74 through portions of dielectric
layer 22 that are not protected by photoresist layer 83, and stops
at plane 45-45 thereby exposing top surface 24t1 on 16-24 kG TS
layer 24, and top surface 24t2 on BGC layer 24b. Front side 22f and
back side 22e of the second dielectric layer are formed in openings
73, 74, respectively.
[0073] In FIG. 23, the partially formed trailing shield structure
is shown after the second 16-24 kG layer is plated to provide TS
layer 25 and BGC layer 25b that fill openings 73, 74, respectively,
and have thickness t2. Another CMP process is employed to form top
surface 25t1 on 16-24 kG TS layer 25, top surface 22t on the second
dielectric layer, and top surface 25t2 on BGC layer 25b at plane
46-46 that is parallel to plane 45-45. Backside 25e on 16-24 kG TS
layer 25 coincides with front side 22f mentioned previously, and
front side 25f on BGC layer 25b coincides with backside 22e on the
second dielectric layer. Thereafter, conventional methods are
followed to form the remainder of the write head including driving
coil 21a in dielectric layer 22, and the PP3 trailing shield 27 or
27-1 with front end 27f that is recessed from the ABS as shown in
FIG. 9a or FIG. 10, respectively.
[0074] In another process embodiment of the present disclosure, the
process flow depicted in FIGS. 13-19 is modified after the step
shown in FIG. 15. In particular, the process flow continues with
the partially formed trailing shield structure illustrated in FIG.
24 after write gap 16 and hot seed layer 17 are sequentially
deposited at plane 41-41 at the ABS. Next, a photoresist layer 84
is coated on the hot seed layer and is patterned by a
photolithography method to generate opening 75 having cross-track
width w that is bisected by center plane 44-44, and uncovers a
portion of the hot seed layer top surface 17t.
[0075] Referring to FIG. 25, the 16-24 kG TS layer 24 is plated in
opening 75. In the following step, photoresist layer 84 is removed
to leave 16-24 kG TS layer sides 24s on each side of center plane
44-44. Portions of hot seed layer top surface 17t adjoining the
sides 24s are uncovered.
[0076] In FIG. 26, the partially formed trailing shield structure
is shown after a RIE or IBE process is performed that removes
portions of hot seed layer 17 and write gap 16 that are not
protected by the 16-24 kG TS layer 24. As a result, openings 76 are
formed at sides 16s, 17s, 24s, and rounded corners 24r are formed
at either end of top surface 24t1. Moreover, the etching process
typically removes a top portion of side shields 12 below plane
41-41 thereby generating a side shield side 12n on either side of
center plane 44-44 where side 12n intersects plane 41-41 at write
gap side 16s and forms an angle .delta. of 20 to 60 degrees with
plane 41-41. Side shield top surface 12t is now a distance r below
plane 41-41 and connects with an end of side 12n that is opposite
to the end at plane 41-41. Thus, distance r varies from a minimum
of 0 nm where side 12n intersects the write gap side to a maximum
of 20 to 100 nm at a far side 60 (or 61) of the side shield.
[0077] Referring to FIG. 27, the 8-16 kG TS layer 23 is plated on
side shield top surfaces 12t and sides 12n to a level that fills
opening 76 on each side of center plane 44-44. A CMP process is
used for planarization so that top surface 23t of the 8-16 kG TS
layer, and top surface 24t1 of the 16-24 kG TS layer are coplanar,
and rounded corners 24r are removed. In the exemplary embodiment,
the CMP process results in a thickness t of about 1 micron for the
16-24 kG TS layer 24. However, the present disclosure also
anticipates that a reduced thickness t1 of about 0.1 to 0.5 micron
could be an alternative outcome for the CMP process. Each 8-16 TS
layer 23 has a thickness equal to (r+a+b+t) as shown in FIG. 27 or
(r+a+b+t1) in FIG. 28.
[0078] In embodiments where the 16-24 kG TS layer 24 has thickness
t1, a second 16-24 kG TS layer 25 may be formed on the top surface
23t of the 8-16 kG TS layer, and on top surface 24t1 of the first
16-24 kG TS layer 24. The second 16-24 kG TS layer preferably has a
full width between trailing shield sides 60, 61, and has thickness
t2 where (t1+t2) equals about 1 micron as explained previously.
Although this embodiment is expected to cause an increase in WATE
because of more topography in the side shields 12 in that side 12n
is not coplanar with top surface 12t, the fact that both side
shields 12 and 8-16 kG TS layer 23 are made of the same magnetic
material substantially mitigates the effect on WATE.
[0079] While the present disclosure has been particularly shown and
described with reference to, the preferred embodiment thereof, it
will be understood by those skilled in the art that various changes
in form and details may be made without departing from the spirit
and scope of this disclosure.
* * * * *