U.S. patent application number 14/156274 was filed with the patent office on 2015-07-16 for fabrication of multiple sensor layers with self-aligned back edge.
This patent application is currently assigned to HGST Netherlands B.V.. The applicant listed for this patent is HGST Netherlands B.V.. Invention is credited to Patrick M. BRAGANCA, Jordan A. KATINE, Yang LI, Neil L. ROBERTSON.
Application Number | 20150199990 14/156274 |
Document ID | / |
Family ID | 53506821 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150199990 |
Kind Code |
A1 |
BRAGANCA; Patrick M. ; et
al. |
July 16, 2015 |
FABRICATION OF MULTIPLE SENSOR LAYERS WITH SELF-ALIGNED BACK
EDGE
Abstract
The embodiments of the present invention relate to a method for
forming a magnetic read head having one or more sensors disposed
over one or more sensors. The method includes forming one or more
first sensors on a shield, forming a spacer layer over the one or
more first sensors and forming one or more second sensors over the
spacer layer. A single photolithography process is performed on a
resist that is disposed over a portion of the one or more second
sensors, the spacer layer and the one or more first sensors, and
portions of the one or more second sensors, the spacer layer and
the one or more first sensors not covered by the resist are removed
by multiple removal processes. The stripe heights of the free
layers and the pinned layers of the one or more first sensors and
the one or more second sensors are defined as a result of the
multiple removal processes.
Inventors: |
BRAGANCA; Patrick M.; (San
Jose, CA) ; LI; Yang; (San Jose, CA) ; KATINE;
Jordan A.; (Mountain View, CA) ; ROBERTSON; Neil
L.; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HGST Netherlands B.V. |
Amsterdam |
|
NL |
|
|
Assignee: |
HGST Netherlands B.V.
Amsterdam
NL
|
Family ID: |
53506821 |
Appl. No.: |
14/156274 |
Filed: |
January 15, 2014 |
Current U.S.
Class: |
360/315 ;
29/603.18 |
Current CPC
Class: |
G11B 5/398 20130101;
G11B 5/3951 20130101; Y10T 29/49052 20150115; G11B 5/84 20130101;
G11B 5/39 20130101; G11B 5/3948 20130101; G11B 5/3163 20130101;
G11B 5/3945 20130101 |
International
Class: |
G11B 5/84 20060101
G11B005/84; G11B 5/39 20060101 G11B005/39 |
Claims
1. A magnetic read head for multiple input multiple output
recording, comprising: side by side sensors disposed over a shield,
wherein the side by side sensors includes: the shield; a first
pinned layer disposed over a portion of the shield; a first spacer
layer disposed over the first pinned layer; a first free layer
disposed over a first portion of the first spacer layer; a second
free layer disposed over a second portion of the first spacer
layer; and an insulative nonmagnetic material disposed over a third
portion of the first spacer layer; a second spacer layer disposed
over the side by side sensors; and one or more second sensors
disposed over the second spacer layer.
2. The magnetic read head of claim 1, wherein the second spacer
layer comprises a material selected from the group consisting of
silicon dioxide, silicon nitride and tantalum oxide.
3. The magnetic read head of claim 2, further comprising a first
lead layer disposed over the first free layer and a second lead
layer disposed over the second free layer.
4. The magnetic read head of claim 1, wherein the second spacer
layer comprises a magnetic metal.
5. The magnetic read head of claim 1, wherein the one or more
second sensors includes: a second pinned layer disposed over the
spacer layer; a third spacer layer disposed over the second pinned
layer; and a third free layer disposed over the third spacer
layer.
6. The magnetic read head of claim 5, wherein the first pinned
layer has a first stripe height, the first free layer has a second
stripe height, the second free layer has a third stripe height, the
third free layer has a fourth stripe height and the second pinned
player has a fifth stripe height.
7. The magnetic read head of claim 6, wherein the second, third,
fourth and fifth stripe heights are substantially the same, and the
first stripe height is greater than the second, third, fourth and
fifth stripe height.
8-20. (canceled)
Description
BACKGROUND
[0001] 1. Field
[0002] Embodiments of the present invention generally relate to a
magnetic read head for use in a hard disk drive.
[0003] 2. Description of the Related Art
[0004] The heart of a computer is a magnetic disk drive which
typically includes a rotating magnetic disk, a slider that has read
and write heads, a suspension arm above the rotating disk and an
actuator arm that swings the suspension arm to place the read
and/or write heads over selected circular tracks on the rotating
disk. The suspension arm biases the slider towards the surface of
the disk when the disk is not rotating but, when the disk rotates,
air is swirled by the rotating disk adjacent an air bearing surface
(ABS) of the slider causing the slider to ride on an air bearing a
slight distance from the surface of the rotating disk. When the
slider rides on the air bearing, the write and read heads are
employed for writing magnetic impressions to and reading magnetic
signal fields from the rotating disk. The read and write heads are
connected to processing circuitry that operates according to a
computer program to implement the writing and reading
functions.
[0005] The read head typically utilizes a spin valve sensor, also
referred to as a magnetoresistive (MR) sensor. The sensor at the
ABS typically includes a spacer layer sandwiched between a pinned
layer and a free layer. The magnetization of the pinned layer is
pinned perpendicular to the ABS and the magnetic moment of the free
layer is located parallel to the ABS, but free to rotate in
response to external magnetic fields.
[0006] The read sensor has an end extending to the ABS and a back
edge which is recessed in the read head that is opposite the ABS.
The back edge is precisely located by photolithographic processing.
During construction, the ABS is also precisely defined so that the
read sensor has a precise stripe height which is the distance
between the ABS and the back edge. Therefore, an improved magnetic
read head and method for forming the magnetic read head is
needed.
SUMMARY OF THE INVENTION
[0007] The embodiments of the present invention relate to a method
for forming a magnetic read head having one or more sensors
disposed over one or more sensors. The method includes forming one
or more first sensors on a shield, forming a spacer layer over the
one or more sensors and forming one or more second sensors over the
spacer layer. A single photolithography process is performed on a
resist that is disposed over a portion of the one or more second
sensors, the spacer layer and the one or more first sensors, and
portions of the one or more second sensors, the spacer layer and
the one or more first sensors not covered by the resist are removed
by multiple removal processes. The stripe heights of the free
layers and the pinned layers of the one or more first sensors and
the one or more second sensors are defined as a result of the
multiple removal processes.
[0008] In one embodiment, a magnetic read head for multiple input
multiple output recording is disclosed. The magnetic read head
includes side by side sensors disposed over a shield, where the
side by side sensors includes a shield, a first pinned layer
disposed over a portion of the shield, a first spacer layer
disposed over the first pinned layer, a first free layer disposed
over a first portion of the first spacer layer, a second free layer
disposed over a second portion of the first spacer layer, and an
insulative nonmagnetic material disposed over a third portion of
the first spacer layer. The magnetic read head further includes a
second spacer layer disposed over the side by side sensors and one
or more second sensors disposed over the spacer layer.
[0009] In another embodiment, a method for forming a magnetic read
head for multiple input multiple output recording is disclosed. The
method includes forming one or more first sensors on a shield,
forming a first spacer layer over the one or more first sensors,
forming one or more second sensors over the first spacer layer, and
forming a resist on the one or more second sensors. The resist
covers a first portion of the one or more second sensors, the first
spacer layer and the one or more first sensors. The method further
includes removing a second portion of the one or more second
sensors to define a first stripe height of a pinned layer and a
free layer of each of the one or more second sensors, removing a
second portion of the first spacer layer, and removing a second
portion of the one or more first sensors to define a second stripe
height of a free layer of each of the one or more first sensors.
The first stripe height is substantially the same as the second
stripe height.
[0010] In another embodiment, a method for forming a magnetic read
head for multiple input multiple output recording is disclosed. The
method includes forming side by side sensors on a shield, forming a
first spacer layer over the side by side sensors, forming a second
sensor over the first spacer layer, and forming a resist on the
second sensor. The resist covers a first portion of the second
sensor, the first spacer layer and the side by side sensors. The
method further includes removing a second portion of the second
sensor to define a first stripe height of a pinned layer and a free
layer of the second sensor, removing a second portion of the first
spacer layer, and removing a second portion of the side by side
sensors to define a second stripe height of a free layer of each of
the side by side sensors. The first stripe height is substantially
the same as the second stripe height.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments in any field involving magnetic sensors.
[0012] FIG. 1 illustrates an exemplary magnetic disk drive,
according to an embodiment of the invention.
[0013] FIG. 2 is a side view of a read/write head and magnetic disk
of the disk drive of FIG. 1, according to one embodiment of the
invention.
[0014] FIG. 3 is an ABS view of a sensor stack of a magnetic read
head according to one embodiment.
[0015] FIG. 4 is an ABS view of a sensor stack of the magnetic read
head according to one embodiment.
[0016] FIG. 5 is an ABS view of a sensor stack of the magnetic read
head according to one embodiment.
[0017] FIGS. 6A-6C are cross sectional side views of the sensor
stack according to one embodiment.
[0018] FIGS. 7A-7C are cross sectional side views of the sensor
stack according to one embodiment.
[0019] FIGS. 8A-8C are cross sectional side views of the sensor
stack according to one embodiment.
[0020] FIGS. 9A-9C are cross sectional side views of the sensor
stack according to one embodiment.
[0021] FIGS. 10A-10C are cross sectional side views of the sensor
stack according to one embodiment.
[0022] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0023] In the following, reference is made to embodiments of the
invention. However, it should be understood that the invention is
not limited to specific described embodiments. Instead, any
combination of the following features and elements, whether related
to different embodiments or not, is contemplated to implement and
practice the invention. Furthermore, although embodiments of the
invention may achieve advantages over other possible solutions
and/or over the prior art, whether or not a particular advantage is
achieved by a given embodiment is not limiting of the invention.
Thus, the following aspects, features, embodiments and advantages
are merely illustrative and are not considered elements or
limitations of the appended claims except where explicitly recited
in a claim(s). Likewise, reference to "the invention" shall not be
construed as a generalization of any inventive subject matter
disclosed herein and shall not be considered to be an element or
limitation of the appended claims except where explicitly recited
in a claim(s).
[0024] The embodiments of the present invention relate to a method
for forming a magnetic read head having one or more sensors
disposed over one or more sensors. The method includes forming one
or more first sensors on a shield, forming a spacer layer over the
one or more sensors and forming one or more second sensors over the
spacer layer. A single photolithography process is performed on a
resist that is disposed over a portion of the one or more second
sensors, the spacer layer and the one or more first sensors, and
portions of the one or more second sensors, the spacer layer and
the one or more first sensors not covered by the resist are removed
by multiple removal processes. The stripe heights of the free
layers and the pinned layers of the one or more first sensors and
the one or more second sensors are defined as a result of the
multiple removal processes.
[0025] FIG. 1 illustrates a top view of an exemplary hard disk
drive (HDD) 100, according to an embodiment of the invention. As
illustrated, HDD 100 may include one or more magnetic disks 110,
actuator 120, actuator arms 130 associated with each of the
magnetic disks 110, and spindle motor 140 affixed in a chassis 150.
The one or more magnetic disks 110 may be arranged vertically as
illustrated in FIG. 1. Moreover, the one or more magnetic disks may
be coupled with the spindle motor 140.
[0026] Magnetic disks 110 may include circular tracks of data on
both the top and bottom surfaces of the disk. A magnetic head 180
mounted on a slider may be positioned on a track. As each disk
spins, data may be written on and/or read from the data track.
Magnetic head 180 may be coupled to an actuator arm 130 as
illustrated in FIG. 1. Actuator arm 130 may be configured to swivel
around actuator axis 131 to place magnetic head 180 on a particular
data track.
[0027] FIG. 2 is a fragmented, cross-sectional side view through
the center of a read/write head 200 mounted on a slider 201 and
facing magnetic disk 202. The read/write head 200 and magnetic disk
202 may correspond to the magnetic head 180 and magnetic disk 110,
respectively in FIG. 1. In some embodiments, the magnetic disk 202
may be a "dual-layer" medium that includes a perpendicular magnetic
data recording layer (RL) 204 on a "soft" or relatively
low-coercivity magnetically permeable underlayer (PL) 206 formed on
a disk substrate 208. The read/write head 200 includes an ABS, a
magnetic write head 210 and a magnetic read head 211, and is
mounted such that the ABS is facing the magnetic disk 202. In FIG.
2, the disk 202 moves past the write head 210 in the direction
indicated by the arrow 232, so the portion of slider 201 that
supports the read/write head 200 is often called the slider
"trailing" end 203.
[0028] The magnetic read head 211 is a magneto-resistive (MR) read
head that includes a MR sensing element 230 located between MR
shields S1 and S2, which are composed of a highly permeable and
magnetically soft material such as permalloy. The distance between
S1 and S2, which is the sensor thickness, defines the read gap of
the read head. The MR sensing element 230 may include multiple
sensors disposed on different levels, which are described in detail
below. The RL 204 is illustrated with perpendicularly recorded or
magnetized regions, with adjacent regions having magnetization
directions, as represented by the arrows located in the RL 204. The
magnetic fields of the adjacent magnetized regions are detectable
by the MR sensing element 230 as the recorded bits.
[0029] The write head 210 includes a magnetic circuit made up of a
main pole 212 and a yoke 216. The write head 210 also includes a
thin film coil 218 shown in the section embedded in non-magnetic
material 219 and wrapped around yoke 216. In an alternative
embodiment, the yoke 216 may be omitted, and the coil 218 may wrap
around the main pole 212. A write pole 220 is magnetically
connected to the main pole 212 and has an end 226 that defines part
of the ABS of the magnetic write head 210 facing the outer surface
of disk 202.
[0030] Write pole 220 is a flared write pole and includes a flare
point 222 and a pole tip 224 that includes an end 226 that defines
part of the ABS. The flare may extend the entire height of write
pole 220 (i.e., from the end 226 of the write pole 220 to the top
of the write pole 220), or may only extend from the flare point
222, as shown in FIG. 2. In one embodiment the distance between the
flare point 222 and the ABS is between about 30 nm and about 150
nm.
[0031] The write pole 220 includes a tapered surface 271 which
increases a width of the write pole 220 from a first width W1 at
the ABS to a second width W2 away from the ABS. In one embodiment,
the width W1 may be between around 60 nm and 200 nm, and the width
W2 may be between around 120 nm and 350 nm. While the tapered
region 271 is shown with a single straight surface in FIG. 2, in
alternative embodiment, the tapered region 271 may include a
plurality of tapered surface with different taper angles with
respect to the ABS.
[0032] The tapering improves magnetic performance. For example,
reducing the width W1 at the ABS may concentrate a magnetic field
generated by the write pole 220 over desirable portions of the
magnetic disk 202. In other words, reducing the width W1 of the
write pole 220 at the ABS reduces the probability that tracks
adjacent to a desirable track are erroneously altered during
writing operations.
[0033] While a small width of the write pole 220 is desired at the
ABS, it may be desirable to have a greater width of the write pole
220 in areas away from the ABS. A larger width W2 of the write pole
220 away from the ABS may desirably increase the magnetic flux to
the write pole 220, by providing a greater thickness of the write
pole 220 in a direction generally parallel to the ABS. In
operation, write current passes through coil 218 and induces a
magnetic field (shown by dashed line 228) from the write pole 220
that passes through the RL 204 (to magnetize the region of the RL
204 beneath the write pole 220), through the flux return path
provided by the PL 206, and back to an upper return pole 250. In
one embodiment, the greater the magnetic flux of the write pole
220, the greater is the probability of accurately writing to
desirable regions of the RL 204.
[0034] FIG. 2 further illustrates one embodiment of the upper
return pole or magnetic shield 250 that is separated from write
pole 220 by a nonmagnetic gap layer 256. In some embodiments, the
magnetic shield 250 may be a trailing shield wherein substantially
all of the shield material is on the trailing end 203.
Alternatively, in some embodiments, the magnetic shield 250 may be
a wrap-around shield wherein the shield covers the trailing end 203
and also wraps around the sides of the write pole 220. As FIG. 2 is
a cross section through the center of the read/write head 200, it
represents both trailing and wrap-around embodiments.
[0035] Near the ABS, the nonmagnetic gap layer 256 has a reduced
thickness and forms a shield gap throat 258. The throat gap width
is generally defined as the distance between the write pole 220 and
the magnetic shield 250 at the ABS. The shield 250 is formed of
magnetically permeable material (such as Ni, Co and Fe alloys) and
gap layer 256 is formed of nonmagnetic material (such as Ta, TaO,
Ru, Rh, NiCr, SiC or Al.sub.2O.sub.3). A taper 260 in the gap
material provides a gradual transition from the throat gap width at
the ABS to a maximum gap width above the taper 260. This gradual
transition in width forms a tapered bump in the non-magnetic gap
layer that allows for greater magnetic flux density from the write
pole 220, while avoiding saturation of the shield 250.
[0036] It should be understood that the taper 260 may extend either
more or less than is shown in FIG. 2. The taper may extend upwards
to an end of shield 250 opposite the ABS (not shown), such that the
maximum gap width is at the end of the shield opposite the ABS. The
gap layer thickness increases from a first thickness (the throat
gap width) at the ABS to greater thicknesses at a first distance
from the ABS, to a final thickness at a second distance (greater
than the first distance) from the ABS.
[0037] FIG. 3 is an ABS view of a sensor stack 300 of the magnetic
read head 211 according to one of the embodiments. The sensor stack
300 includes side by side sensors 332, 334, each having its own
lead layer 320, 318, capping layer 316, 314, and free layer 312,
310, respectively. The capping layer 314 and the free layer 310 are
separated from the capping layer 316 and free layer 312 by an
insulative nonmagnetic material 330. The insulative nonmagnetic
material 330 may comprise a bilayer structure including a first
layer of alumina formed on a spacer layer 308, and a second layer
of SiO.sub.x or TaO.sub.x formed on the first layer. The sensors
332, 334 share the spacer layer 308 and a pinned layer 306 and are
disposed on a seed layer 304, which is disposed on a shield 302.
The shield 302 may be the shield S1 and may comprise a
ferromagnetic material. Suitable ferromagnetic materials that may
be utilized include Ni, Fe, Co, NiFe, NiFeCo, NiCo, CoFe and
combinations thereof. The seed layer 304 may comprise Ta or Ru. The
pinned layer 306 may be a ferromagnetic layer comprising NiFe,
CoFe, CoFeB, Co, CoZr, CoHf or CoFeTaB. The pinned layer 306 may
comprise a multilayer structure such as an antiparallel (AP) pinned
structure having a first magnetic layer, a second magnetic layer
and a nonmagnetic AP coupling layer sandwiched between the two
magnetic layers. The first and second magnetic layers may be
constructed of several magnetic materials such as, for example
NiFe, CoFe, CoFeB, Co, CoZr, CoHf or CoFeTaB. The nonmagnetic layer
may comprise Ru. The spacer layer 308 may comprise an insulating
material such as MgO, TiO.sub.2 or alumina, or a nonmagnetic
material such as Cu, Ag or the like. The free layers 310, 312 may
comprise ferromagnetic materials such as Co, CoFe, CoFeB, NiFe,
CoHf or combinations thereof. The capping layers 314, 316 may
comprise a material such as Ru, Ta or a layered structure of these
materials. The lead layers 318, 320 may comprise any refractory
hard metal that is reactive ion etchable, such as W, or magnetic
material such as CoFe, NiFe or the like.
[0038] Adjacent the sensors 332, 334 is a bias material 322. The
bias material 322 may be a hard or soft bias comprising a material
having a high magnetic moment such as CoFe or NiFe. An insulating
layer 324 is first deposited on the shield 302 and the side walls
336, 338, of the sensors 332, 334, respectively, and then the bias
material 322 is deposited on the insulating layer 324. The
insulating layer 314 may be made of an insulating material such as
alumina, silicon nitride, silicon dioxide, tantalum oxide or other
suitable materials. A bias capping layer 326 may be deposited on
the bias material 322. The layers 304, 306, 308, 310, 312, 314,
316, 318, 320, 322, 324, 326 and 330 may be deposited by physical
vapor deposition (PVD), chemical vapor deposition, ion beam
deposition (IBD) or any other suitable deposition method. At this
stage, the stripe heights of the pinned layer 306 and the free
layers 310, 312 have not been defined, meaning, the sensor stack
300 as shown in FIG. 3 extends at least 1 micrometer into the
page.
[0039] Next, as shown in FIG. 4, a spacer layer 402 is formed on
the lead layers 318, 320 and the insulative nonmagnetic material
330. In one embodiment, the spacer layer 402 comprises a fluorine
chemistry reactive ion etchable (RIEable) insulative material such
as SiO.sub.x, TaO.sub.x or other suitable insulative material, and
may have a thickness of greater than 15 nm. In another embodiment,
the spacer layer 402 comprises a magnetic metal shield and the lead
layers 318, 320 are not present. The metal spacer layer 402 may be
a RIEable metal such as W, Ta, Ti, or a non-RIEable metal such as
NiFe or Rh. If a soft magnetic material is used, it can serve as a
middle shield which would improve the downtrack resolution of the
sensors. One drawback of using non-RIEable materials is that this
spacer layer 402 would then require ion milling to etch, which
would tighten the process tolerances. A top surface 404 of the
sensor stack 300 may be planarized by a chemical mechanical
polishing (CMP) process.
[0040] As shown in FIG. 5, a seed layer 502 is deposited on the
spacer layer 402. The seed layer 502 may comprise Ta, Ru or other
suitable material. In one embodiment, both seed layers 304, 502 are
made of the same material. In another embodiment, both seed layers
304, 502 are made of different materials. A pinned layer 504 is
deposited on the seed layer 502. The pinned layer 504 may comprise
the same material as the pinned layer 306. A spacer layer 506 is
deposited on the pinned layer 504, a free layer 508 is deposited on
the spacer layer 506, and a capping layer 510 is deposited on the
free layer 508. The pinned layer 504 may comprise the same material
as the pinned layer 306, the free layer 508 may comprise the same
material as free layers 310, 312, and the capping layer 510 may
comprise the same material as capping layers 314, 316. As shown in
FIG. 5, the resulting sensor stack 300 has side by side sensors
332, 334 disposed on a first level and a sensor 512 disposed on a
second level that is over first level. The sensors 332, 334, 512
may be used for multiple input multiple output (MIMO) recording.
The number of sensors for MIMO recording is not limited to two on
the first level and one on the second level. In one embodiment, the
first level has one sensor and the second level has one sensor. In
another embodiment, the first level has one sensor and the second
level has two sensors. In yet another embodiment, there are two
sensors on each level.
[0041] As mentioned above, stripe heights of the pinned layers 306,
504 and free layers 310, 312, 508 have not been defined. A method
for forming self-aligned back edges, i.e., defining stripe heights,
of the pinned layer 504 and free layers 310, 312, 508, is described
below.
[0042] FIGS. 6A-6C, 7A-7C, 8A-8C, 9A-9C and 10A-10C are cross
sectional views of the sensor stack 300 at locations A, B and C
shown in FIG. 5 at various process stages. FIGS. 6A, 7A, 8A, 9A and
10A are cross sectional views at location A, FIGS. 6B, 7B, 8B, 9B
and 10B are cross sectional views at location B, and FIGS. 6C, 7C,
8C, 9C and 10C are cross sectional views at location C. FIG. 6A is
a cross sectional view of the sensor stack 300 at location A shown
in FIG. 5. The layers 510, 508, 506, 504, 502, 402, 320, 326, 322,
324 and 302 have a first end at the ABS and a second end at a
location 602 that is recessed from the ABS. FIG. 6B is a cross
sectional view of the sensor stack 300 at location B shown in FIG.
5. Similarly, the layers 510, 508, 506, 504, 502, 402, 330, 308,
306, 304 and 302 have a first end at the ABS and the second end at
the location 602 that is recessed from the ABS. FIG. 6C is a cross
sectional view of the sensor stack 300 at location C shown in FIG.
5. Again the layers 510, 508, 506, 504, 502, 402, 318, 314, 310,
308, 306, 304 and 302 have a first end at the ABS and the second
end at the location 602 recessed from the ABS.
[0043] Next, a resist 702 is formed on the capping layer 510 that
covers a portion of the capping layer 510 that extends to the ABS,
as shown in FIGS. 7A-7C. The resist 702 may be formed by a single
photolithography process, and as described in detail below, this
single photolithography process helps form the self-aligned back
edges of the free layers 508, 310, 312 and the pinned layer 504. In
other words, the pinned layer and the free layer of the top sensor,
and the free layers of the bottom sensors are aligned with just one
photolithography process, while the shared pinned layer of the
bottom sensors is an extended pinned layer (EPL) which enhances the
stability of the shared pinned layer of the bottom side by side
sensors. The EPL does not have a back edge that is aligned with the
back edges of the free layers of the sensors on both levels and the
pinned layer of the sensor on the second level. In some
embodiments, it may be advantageous to completely etch through the
pinned layer of the bottom sensors, and that may be accomplished in
a self-aligned process as the one described here by simply
extending the etching time.
[0044] Portions of the capping layer 510, free layer 508, spacer
layer 506, pinned layer 504, and seed layer 502 not covered by the
resist 702 are then removed by an ion milling process to expose a
portion of the spacer layer 402. In one embodiment, the ion milling
process also removes a portion of the spacer layer 402, as shown in
FIGS. 7A-7C. Since the spacer layer 402 is relatively thick, such
as over 15 nm, stopping the ion milling process somewhere in the
spacer layer 402 is easy to achieve. The layers 510, 508, 506, 504
and 502 have one end at the ABS, but the other end (the back edge)
is at a location 704 that is also recessed from the ABS, but is
closer to the ABS than the location 602. As a result of the removal
process, the stripe heights of the free layer 508 and the pinned
layer 504 of the top sensor 512 are defined, indicated as "D1." In
one embodiment, the stripe height "D1" is about 30 nm. In one
embodiment, a protective layer (not shown) may be deposited on the
back edge of the sensor 512 to prevent corrosion during subsequent
reactive ion etching (RIE) processes. The protective layer may be
alumina or silicon nitride.
[0045] Next, a removal process is performed to remove portions of
the spacer layer 402 and the lead layer 320 not covered by the
resist 702 to expose a portion of the bias capping layer 326 at
location A (FIG. 5), as shown in FIG. 8A. The removal process also
removes portions of the spacer layer 402 and the insulative
nonmagnetic material 330 not covered by the resist to expose a
portion of the spacer layer 308 at location B (FIG. 5), as shown in
FIG. 8B. If the spacer layer 402 is a material such as silicon
dioxide, silicon nitride, or tantalum oxide that can be etched
using a fluorine based RIE, this etch would also attack the
insulative nonmagnetic material 330 beneath the spacer layer 402 at
location B if the insulative nonmagnetic material 330 were made of
similar materials. That is one reason that the insulative
nonmagnetic material 330 includes aluminum oxide or a similar
insulating material that is not etched in a fluorine RIE chemistry.
The non-RIEable insulative nonmagnetic material 330 protects the
spacer layer 308 at location B during the RIE step. At location C
(FIG. 5), portions of the spacer layer 402 and lead layer 318 not
covered by the resist 702 are removed to expose a portion of the
capping layer 314. The removal process may be a RIE process if both
the spacer layer 402 and the lead layer 318 are etchable in a
fluorine based RIE, or a RIE process followed by ion milling if the
lead layer 318 cannot be etched in the same chemistry as the spacer
layer 402.
[0046] An ion milling step is then performed. At location A this
mill will remove portions of the bias capping layer 326 and bias
material 322 that are not covered by the resist 702 to expose a
portion of the bias material 322, as shown in FIG. 9A. In one
embodiment, the bias capping layer 326 is comprised of a material
that is resistant to ion milling, thus, the bias material 322 is
not affected by the ion milling process. In another embodiment, the
portion of the bias material 322 not covered by the resist 702 is
removed by the ion milling process. In that event, it is important
that this removal not adversely affect the ability of the bias
material 322 to stabilize the sensors 332, 334. Depending on how
much of the insulative nonmagnetic material 330 remains after the
RIE is completed (FIG. 8B), the ion milling process may also remove
a portion of the spacer layer 308 that is not covered by the resist
702 to expose the pinned layer 306 at location B (FIG. 5), as shown
in FIG. 9B. If too much of pinned layer 306 were to be ion milled,
it could affect the shared pinned layer 306, therefore in one
embodiment, the materials for insulative nonmagnetic material 330
are chosen so that milling of the pinned layer 306 in FIG. 9B does
not occur or is minimal. Portions of the capping layer 314, the
free layer 310 and the spacer layer 308 not covered by the resist
702 are also removed by the ion milling process to expose the a
portion of the pinned layer 306 at location C (FIG. 5), as shown in
FIG. 9C. The ion milling rate of the spacer layer 308 is much
slower than the milling rates of the capping layer 314 and the free
layer 310, so there is ample process latitude to remove the free
layer 310, with no or minimal milling into the pinned layer 306.
The ion milling process aligns the back edges of the free layers
310, 316 with the back edges of the pinned layer 504 and the free
layer 508 of the top sensor 512, causing the stripe heights of the
free layers 310, 316 and 508 and the pinned layer 504 to be
substantially identical. The ion milling process should not remove
any portion of the pinned layer 306. Thus, the pinned layer 306 is
an EPL which has a greater stripe height than the free layers 310,
316, 508 and the pinned layer 504. In other words, the pinned layer
of the bottom sensor(s) is an EPL and the free layers of the bottom
sensor(s), the free layers of the top sensor(s), and the pinned
layer(s) of the top sensor(s) all have the same stripe height. In
other embodiments, the ion milling process also removes a portion
of the pinned layer 306, so the stripe height of the pinned layer
306 is the same as the stripe height of the free layers 310, 316
and 508 and the pinned layer 504, and the pinned layer 306 is not
an EPL.
[0047] Next, an insulating material 1002 is formed on the exposed
bias material 322 at location A (FIG. 5), as shown in FIG. 10A. The
insulating material 1002 is also formed on the exposed pinned layer
306 at location B (FIG. 5), as shown in FIG. 10B, and at location C
(FIG. 5), as shown in FIG. 10C. The resist 702 is removed by a lift
off process and a top surface 1004 may be planarized by a CMP
process.
[0048] In summary, a method for forming a magnetic read head having
sensors on multiple levels is disclosed. The method includes
forming a sensor on a second level that is over a first level on
which side by side sensors are disposed. A photolithograph process
is performed to form a resist that is disposed on the sensor on the
second level. Portions of the free layers of the top and bottom
sensors and the pinned layer of the top sensor not covered by the
resist are removed through multiple removal processes. As a result,
the stripe heights of the layers are defined and are the same for
these layers. The pinned layer of the bottom sensor is not affected
by the multiple removal process and is an EPL.
[0049] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *