U.S. patent application number 14/844312 was filed with the patent office on 2015-12-31 for heated afm layer deposition and cooling process for tmr magnetic recording sensor with high pinning field.
The applicant listed for this patent is Western Digital (Fremont), LLC. Invention is credited to ZHITAO DIAO, XIN JIANG, CHRISTIAN KAISER, QUNWEN LENG, TONG ZHAO, YUANKAI ZHENG.
Application Number | 20150380026 14/844312 |
Document ID | / |
Family ID | 54149674 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150380026 |
Kind Code |
A1 |
ZHENG; YUANKAI ; et
al. |
December 31, 2015 |
HEATED AFM LAYER DEPOSITION AND COOLING PROCESS FOR TMR MAGNETIC
RECORDING SENSOR WITH HIGH PINNING FIELD
Abstract
Systems and methods are provided for manufacturing a magnetic
recording sensor for use in a magnetic reader, such as a tunneling
magnetoresistance (TMR) readers. The magnetic recording sensor can
be manufactured by heating a substrate in a first chamber and
depositing an antiferromagnetic (AFM) layer on the heated
substrate. Additionally, a first pinned layer is added onto the AFM
layer, and the substrate is subsequently cooled.
Inventors: |
ZHENG; YUANKAI; (FREMONT,
CA) ; LENG; QUNWEN; (PALO ALTO, CA) ; ZHAO;
TONG; (FREMONT, CA) ; KAISER; CHRISTIAN; (SAN
JOSE, CA) ; DIAO; ZHITAO; (FREMONT, CA) ;
JIANG; XIN; (SAN JOSE, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Western Digital (Fremont), LLC |
Fremont |
CA |
US |
|
|
Family ID: |
54149674 |
Appl. No.: |
14/844312 |
Filed: |
September 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14216285 |
Mar 17, 2014 |
9147408 |
|
|
14844312 |
|
|
|
|
61918155 |
Dec 19, 2013 |
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Current U.S.
Class: |
360/99.08 ;
360/313; 427/58 |
Current CPC
Class: |
H01F 10/3295 20130101;
H01F 10/3277 20130101; H01F 10/3268 20130101; G11B 5/37 20130101;
G11B 5/3163 20130101; H01L 43/08 20130101; G01R 33/098 20130101;
H01L 43/12 20130101; G11B 5/3909 20130101 |
International
Class: |
G11B 5/39 20060101
G11B005/39 |
Claims
1. A hard disk drive, comprising: a rotatable disk having a disk
surface; a disk drive base; a spindle motor attached to the disk
drive base and configured to support the disk for rotating the disk
with respect to the disk drive base surface; and a reader created
by a process, the process comprising: heating the substrate in a
first chamber; depositing an antiferromagnetic (AFM) layer on the
heated substrate; adding a first pinned layer on the AFM layer; and
cooling the substrate after adding the first pinned layer.
2. A TMR reader created by a process, the process comprising:
heating the substrate in a first chamber; depositing an
antiferromagnetic (AFM) layer on the heated substrate; adding a
first pinned layer on the AFM layer; and cooling the substrate
after adding the first pinned layer.
3. The TMR reader of claim 2, wherein prior to heating, the
substrate comprises: a shield layer; a magnetic seed layer on the
shield layer; and a spacer on the magnetic seed layer
4. The TMR reader of claim 2, wherein the heated substrate is
maintained at an approximately constant temperature during the
operation of depositing the AFM layer.
5. The TMR reader of claim 4, wherein the substrate is heated to a
temperature between 100.degree. C. and 300.degree. C.
6. The TMR reader of claim 5, wherein the temperature of the
substrate is less than 100.degree. C. after cooling the
substrate.
7. The TMR reader of claim 5, wherein the substrate is heated using
a resistor process.
8. The TMR reader of claim 5, wherein the substrate is heated using
a rapid thermal process.
9. The TMR reader of claim 5, wherein the AFM layer is deposited in
the chamber that the substrate is heated.
10. The TMR reader of claim 5, wherein the substrate is moved to a
second chamber prior to performing the operation of depositing the
AFM layer.
11. The TMR reader of claim 2, further comprising adding a second
pinned layer on the first pinned layer after cooling the
substrate.
12. The TMR reader of claim 11, wherein the operation of cooling
provides lower interlayer diffusion between the first pinned layer
and the second pinned layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 14/216,285, filed Mar. 17, 2014, entitled
"HEATED AFM LAYER DEPOSITION AND COOLING PROCESS FOR TMR MAGNETIC
RECORDING SENSOR WITH HIGH PINNING FIELD" (WD Docket No. T6728)
which claims the benefit of U.S. Provisional Application Ser. No.
61/918,155 (Atty. Docket No. F6728.P), filed Dec. 19, 2013, which
is incorporated herein by reference in its entirety.
BACKGROUND
[0002] In magnetic storage devices such as hard disk drives (HDD),
read and write heads are used to magnetically read and write
information to and from storage media. In a HDD, data may be stored
on one or more disks in a series of adjacent concentric circles
which may be referred to as data tracks. A HDD may include a rotary
actuator, a suspension mounted on an arm of the rotary actuator,
and a slider bonded to the suspension to form a head gimbal
assembly (HGA). In a traditional HDD, the slider carries a write
head and read head, and radially floats over the surface of the
storage media, e.g., a disk, under the control of a servo control
system that selectively positions a head over a specific track of
the disk. In this one read head (reader) configuration, the reader
is aligned over the center of a track for data read back.
[0003] As HDD storage capacities have increased, the data track
separation has decreased and the density has increased. Smaller
reader dimensions are required to meet these requirements of
increasing track density and linear density. In tunneling
magnetoresistance (TMR) readers, for example, this may involve
decreasing the volume of the antiferromagnetic (AFM) layer. This
reduction in volume reduces the blocking temperature distribution
(TbD) and the pinning magnetic field strength (H.sub.ex) in the TMR
reader, thereby worsening the thermal stability of the pinned
layer. Accordingly, as the size of the TMR reader decreases, the
pinning strength or exchange field needs to be increased to keep
the pinned layer stable. Prior processes have focused on heating
the AFM layer after its deposition to improve the pinning field.
However, this process does not improve the blocking
temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The present application is illustrated by way of example,
and not limitation, in the figures of the accompanying drawings in
which:
[0005] FIG. 1 is an operational flow diagram illustrating an
example prior art process for manufacturing a magnetic recording
sensor having a conventional structure without a heating/cooling
process;
[0006] FIG. 2 is an operational flow diagram illustrating an
example process for manufacturing a magnetic recording sensor in
accordance with various embodiments;
[0007] FIG. 3 illustrates an example magnetic recording sensor
structure manufactured in accordance with various embodiments.
[0008] FIG. 4 is an example graph indicative of magnetoresistance
(MR) as a function of resistance area (RA) for a recording sensor
manufactured in accordance with various embodiments; and
[0009] FIG. 5 is an example graph indicative of the dependence of
pinning magnetic field strength (H.sub.ex) on incoming wafer degas
pressure.
DETAILED DESCRIPTION
[0010] In the following description, numerous specific details are
set forth to provide a thorough understanding of various embodiment
of the present disclosure. It will be apparent to one skilled in
the art, however, that these specific details need not be employed
to practice various embodiments of the present disclosure. In other
instances, well known components or methods have not been described
in detail to avoid unnecessarily obscuring various embodiments of
the present disclosure.
[0011] The terms "over," "under," "between," and "on" as used
herein refer to a relative position of one media layer with respect
to other layers. As such, for example, one layer disposed over or
under another layer may be directly in contact with the other layer
or may have one or more intervening layers. Moreover, one layer
disposed between two layers may be directly in contact with the two
layers or may have one or more intervening layers. By contrast, a
first layer "on" a second layer is in contact with that second
layer. Additionally, the relative position of one layer with
respect to other layers is provided assuming operations are
performed relative to a substrate without consideration of the
absolute orientation of the substrate.
[0012] In accordance with the present disclosure, systems and
methods for manufacturing a TMR magnetic recording sensor with a
high pinning field are disclosed. In the present disclosure, a
substrate may be heated prior to AFM layer deposition. This is in
contrast to prior methods and structures, which either manufacture
the TMR structure without heating or perform heating after the AFM
layer deposition.
[0013] For example, FIG. 1 is an operational flow diagram
illustrating an example prior art process for manufacturing a
magnetic recording sensor having a conventional structure without a
heating/cooling process. Process 100 may begin at operation 102,
where a substrate is provided. At operation 104, an AFM layer is
then deposited on the substrate. At operation 106, the substrate is
heated in a chamber or station of a disk processing system. At
operation 108, the substrate is subsequently cooled. At operation
110, a first pinned layer is added onto the AFM layer. When a
conventional structure is not heated/cooled at all, a substrate can
be provided, an AFM layer may be deposited on the substrate, and a
pinned layer can be added onto the AFM layer.
[0014] FIG. 2 illustrates an operational flow diagram illustrating
an example process 200 for manufacturing a magnetic recording
sensor in accordance with various embodiments. Process 200 may
begin at operation 202 by providing a substrate. At operation 204,
the substrate may be heated in a chamber or station of a disk
processing system. At operation 206, an AFM layer may be deposited
on the heated substrate. At operation 208, a first pinned layer can
be added onto the AFM layer. At operation 210, the substrate can be
cooled. At operation 212, a second pinned layer can be added onto
the first pinned layer.
[0015] FIG. 3 illustrates a TMR stack 300 that may be manufactured
utilizing process 200 of FIG. 2 in accordance with the present
disclosure. TMR stack 300 may include a shield layer, a seed layer,
a spacer, an AFM layer, a first pinned layer, a second pinned
layer, a Ruthenium (Ru) spacer, a reference layer, a barrier, a
free layer and a cap layer. In one embodiment, the AFM layer
comprises Iridium Manganese (IrMn).
[0016] As illustrated in FIG. 3, the substrate is heated prior to
depositing the AFM layer as described above at operation 204 of
FIG. 2. In accordance with various embodiments, the substrate may
be heated at temperatures ranging from 100.degree. C. to
300.degree. C. In one embodiment, heating can be performed by a
resistive process. In another embodiment the heating can be
accomplished using a rapid thermal process. In one embodiment,
heating may be performed in the same chamber that the AFM layer is
deposited. In an alternative embodiment, TMR stack 300 can be
transferred to another chamber after heating of the substrate and
before deposition of the AFM layer. During deposition of the AFM
layer, TMR stack 300 can be maintained at approximately the
temperature that the substrate was heated.
[0017] After deposition of the AFM layer at the heating
temperature, the first pinned layer is deposited. A cooling process
may then be performed as described above at operation 210 of FIG.
2. Cooling can occur at temperatures ranging between -222.degree.
C. to -2.degree. C. In one embodiment, the temperature of TMR stack
300 is less than 101.degree. C. after cooling.
[0018] Table 1 illustrates the performance characteristics of a TMR
reader manufactured using two conventional processes versus a TMR
reader manufactured using the process disclosed in the present
disclosure. The operations of each process are illustrated from
left to right under the "Structure" heading. In the disclosed
process, a second pinned layer (P1b) is formed in addition to the
first pinned layer (P1a).
TABLE-US-00001 TABLE 1 Structure Bi-layer MOKE CIPT Heat AFM Heat
Cool P1a Cool P1b Hcp Hex Tbd_50% H's Hex RA MR No Y No No Y N N
478 1954 245 3508 5546 0.46 78 No Y Yes Yes Y N N 591 2863 240 3690
6082 0.42 73 Yes Y No No Y Y Y 808 2982 288 4043 6924 0.44 87
[0019] As illustrated in Table 1, the disclosed process
manufactures a TMR reader with an improved bi-layer performance,
showing a higher pinned layer coercivity (Hcp), higher pinning
magnetic field strength (Hex), and higher blocking temperature
distribution (Tbd) than prior conventional processes. The TMR
reader manufactured in accordance with the process disclosed herein
also shows an improved full stack exchange bias (H's). As
illustrated in FIG. 4, the TMR reader also shows an improved
magnetoresistance (MR) as a function of the resistance area (RA).
Such improvements are evidenced, as indicated in Table 1, by the
Magneto Optical Kerr Effect (MOKE) which describes changes to light
reflected from a magnetized surface and therefore indicative of the
magnetization structure of a material, as well as Current In Plane
Tunneling (CIPT) for measuring the properties of a tunnel
junction.
[0020] Table 2 and FIG. 5 illustrate the pinning dependence of the
wafer at different wafer degas pressures (p_ChE) in units of
e*10.sup.-8 Torr for the TMR reader of the present disclosure and
the conventional heat and cool after AFM deposition TMR reader. As
illustrated in Table 2, the conventional TMR reader's coercivity
and pinning magnetic field strength is highly dependent on the
degas pressure. By contrast, the coercivity and pinning magnetic
field strength of the TMR reader of the present disclosure has
little dependence on the degas pressure.
TABLE-US-00002 TABLE 2 Process Wafer ID Hcp Hex p_ChE(e-8 Torr) Old
heat/cool Wafer 1 612 -2715 4.8 Wafer 2 605 -2657 5.2 Wafer 3 573
-2626 5 Wafer 4 513 -2481 5.8 Wafer 5 567 -2535 6 In situ heat
Wafer 6 743 -3034 4.8 P1/cool/P1 Wafer 7 746 -3038 5.2 Wafer 8 751
-3043 6 Wafer 9 751 -3030 6.4 Wafer 10 750 -2906 9
[0021] The system and process for manufacturing a TMR reader
provides many benefits. First, it improves the pinning strength of
the TMR reader. Second, it improves the blocking temperature
distribution. This in turn may improve the TMR device reliability
and allow for a reduction of the thickness of the IrMn AFM layer.
In one embodiment, the thickness of the layer may be reduced to 50
angstroms. Third, the in-coming wafer degas effect is substantially
reduced. Fourth, due to the heating treatment prior to the AFM
layer deposition, the illustrated process produces a smoother film
than prior processes. It should be noted that although various
embodiments described herein have been presented in the context of
a TMR sensor, the systems and methods of manufacturing a recording
sensor are contemplated to be applicable to other sensors, such as
a current perpendicular to plane-giant magnetoresistance (CPP-GMR)
sensor, to Magnetic Random Access Memory (MRAM) or other types of
magnetic sensing or memory devices.
[0022] Although described above in terms of various exemplary
embodiments and implementations, it should be understood that the
various features, aspects and functionality described in one or
more of the individual embodiments are not limited in their
applicability to the particular embodiment with which they are
described, but instead can be applied, alone or in various
combinations, to one or more of the other embodiments of the
application, whether or not such embodiments are described and
whether or not such features are presented as being a part of a
described embodiment. Thus, the breadth and scope of the present
application should not be limited by any of the above-described
exemplary embodiments.
[0023] Terms and phrases used in this document, and variations
thereof, unless otherwise expressly stated, should be construed as
open ended as opposed to limiting. As examples of the foregoing:
the term "including" should be read as meaning "including, without
limitation" or the like; the term "example" is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof; the terms "a" or "an" should be read as
meaning "at least one," "one or more" or the like; and adjectives
such as "conventional," "traditional," "normal," "standard,"
"known" and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time, but instead should be read to
encompass conventional, traditional, normal, or standard
technologies that may be available or known now or at any time in
the future Likewise, where this document refers to technologies
that would be apparent or known to one of ordinary skill in the
art, such technologies encompass those apparent or known to the
skilled artisan now or at any time in the future.
[0024] The presence of broadening words and phrases such as "one or
more," "at least," "but not limited to" or other like phrases in
some instances shall not be read to mean that the narrower case is
intended or required in instances where such broadening phrases may
be absent. The use of the term "module" does not imply that the
components or functionality described or claimed as part of the
module are all configured in a common package. Indeed, any or all
of the various components of a module, whether control logic or
other components, can be combined in a single package or separately
maintained and can further be distributed in multiple groupings or
packages or across multiple locations.
[0025] Additionally, the various embodiments set forth herein are
described in terms of exemplary block diagrams, flow charts and
other illustrations. As will become apparent to one of ordinary
skill in the art after reading this document, the illustrated
embodiments and their various alternatives can be implemented
without confinement to the illustrated examples. For example, block
diagrams and their accompanying description should not be construed
as mandating a particular architecture or configuration.
* * * * *