U.S. patent application number 13/923518 was filed with the patent office on 2014-12-25 for enhanced pinning property by inserted si seed layer.
This patent application is currently assigned to HGST NETHERLANDS B.V.. The applicant listed for this patent is Koujiro KOMAGAKI, Kouichi NISHIOKA. Invention is credited to Koujiro KOMAGAKI, Kouichi NISHIOKA.
Application Number | 20140377588 13/923518 |
Document ID | / |
Family ID | 51948429 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140377588 |
Kind Code |
A1 |
KOMAGAKI; Koujiro ; et
al. |
December 25, 2014 |
ENHANCED PINNING PROPERTY BY INSERTED SI SEED LAYER
Abstract
The embodiments of the present invention generally relate to a
magnetic head having a silicon seed layer disposed between a lower
shield and a metallic underlayer to enhance the unidirectional
anisotropy in an antiferromagnetic layer disposed over the metallic
underlayer.
Inventors: |
KOMAGAKI; Koujiro; (Odawara,
JP) ; NISHIOKA; Kouichi; (Hiratsuka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMAGAKI; Koujiro
NISHIOKA; Kouichi |
Odawara
Hiratsuka |
|
JP
JP |
|
|
Assignee: |
HGST NETHERLANDS B.V.
Amsterdam
NL
|
Family ID: |
51948429 |
Appl. No.: |
13/923518 |
Filed: |
June 21, 2013 |
Current U.S.
Class: |
428/811.2 |
Current CPC
Class: |
Y10T 428/1121 20150115;
G11B 5/3116 20130101; G11B 5/1278 20130101; G11B 5/3906 20130101;
G11B 5/3929 20130101 |
Class at
Publication: |
428/811.2 |
International
Class: |
G11B 5/39 20060101
G11B005/39 |
Claims
1. A magnetic head, comprising: a first shield; a silicon seed
layer disposed over the first shield; a metallic underlayer
disposed over the silicon seed layer, wherein the metallic
underlayer comprises a first metallic sublayer and a second
metallic sublayer; and an antiferromagnetic layer disposed over the
metallic underlayer.
2. The magnetic head of claim 1, wherein the silicon seed layer has
a thickness ranging from about 0.2 nm to about 1 nm.
3. The magnetic head of claim 1, wherein the first metallic
sublayer comprises a material selected from the group consisting of
NiFe, NiCr, Ru, Cu, and combinations thereof.
4. The magnetic head of claim 3, wherein the second metallic
sublayer comprises a material selected from the group consisting of
Ta, Hf, and alloys thereof.
5. The magnetic head of claim 1, wherein the antiferromagnetic
layer comprises IrMn or PtMn.
6. The magnetic head of claim 1, further comprising: a pinned
magnetic layer disposed over the antiferromagnetic layer; an
interlayer disposed over the pinned magnetic layer; a free layer
disposed over the interlayer; a capping layer disposed over the
free layer; and a second shield disposed over the capping
layer.
7. The magnetic head of claim 6, wherein the pinned magnetic layer
comprises CoFe.
8. The magnetic head of claim 6, wherein the pinned magnetic layer
comprises a first magnetic layer, a second magnetic layer, and a
nonmagnetic layer sandwiched between the first and second magnetic
layers.
9. The magnetic head of claim 8, wherein the first magnetic layer
comprises CoFe, the second magnetic layer comprises a material
selected from the group consisting CoFe and CoFeB, and the
nonmagnetic layer comprises a material selected from the group
consisting Ru, Rh, Ir, Cu, and alloys thereof.
10. The magnetic head of claim 6, wherein the interlayer comprises
a material selected from the group consisting Al, Si, Mg, Ca, Sr,
and Zn.
11. The magnetic head of claim 6, wherein the free layer comprises
a first magnetic layer comprising CoFe and a second magnetic layer
comprising NiFe.
12. A magnetic head, comprising: a first shield; a silicon seed
layer disposed over the first shield; a metallic underlayer
disposed over the silicon seed layer, wherein the metallic
underlayer comprises at least a tantalum sublayer; and an
antiferromagnetic layer disposed over the metallic underlayer.
13. The magnetic head of claim 12, wherein the silicon seed layer
has a thickness ranging from about 0.2 nm to about 1 nm.
14. The magnetic head of claim 12, wherein the metallic underlayer
further comprises a metallic sublayer comprising a material
selected from the group consisting NiFe, NiCr, Ru, Cu and
combinations thereof.
15. The magnetic head of claim 12, wherein the antiferromagnetic
layer comprises IrMn or PtMn.
16. The magnetic head of claim 12, further comprising: a pinned
magnetic layer disposed over the antiferromagnetic layer; an
interlayer disposed over the pinned magnetic layer; a free layer
disposed over the interlayer; a capping layer disposed over the
free layer; and a second shield disposed over the capping
layer.
17. A magnetic head, comprising: a first shield; a silicon seed
layer disposed over the first shield; a metallic underlayer
disposed over the silicon seed layer, wherein the metallic
underlayer comprises a tantalum layer and a NiFe layer; and an
antiferromagnetic layer disposed over the metallic underlayer.
18. The magnetic head of claim 17, wherein the silicon seed layer
has a thickness ranging from about 0.2 nm to about 1 nm.
19. The magnetic head of claim 17, wherein the antiferromagnetic
layer comprises IrMn or PtMn.
20. The magnetic head of claim 17, further comprising: a pinned
magnetic layer disposed over the antiferromagnetic layer; an
interlayer disposed over the pinned magnetic layer; a free layer
disposed over the interlayer; a capping layer disposed over the
free layer; and a second shield disposed over the capping layer.
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 into contact with 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-type
magnetoresistive (MR) sensor, which has an antiferromagnetic layer,
a pinned layer, an interlayer, and a free layer disposed between
two magnetic shields. In order for the MR sensor to function
correctly, the magnetization of the pinned layer may be pinned in
one direction. The pinning of the magnetization direction of the
pinned layer is achieved by unidirectional anisotropy induced from
the antiferromagnetic layer.
[0006] Therefore, there is a need in the art for an improved MR
sensor having high unidirectional anisotropy.
SUMMARY OF THE INVENTION
[0007] The embodiments of the present invention generally relate to
a magnetic head having a silicon seed layer disposed between a
lower shield and a metallic underlayer to enhance the
unidirectional anisotropy in an antiferromagnetic layer disposed
over the metallic underlayer.
[0008] In one embodiment, a magnetic head is disclosed. The
magnetic head includes a first shield, a silicon seed layer
disposed over the first shield, and a metallic underlayer disposed
over the silicon seed layer. The metallic underlayer includes a
first metallic sublayer and a second metallic sublayer. The
magnetic head further includes an antiferromagnetic layer disposed
over the metallic underlayer.
[0009] In another embodiment, a magnetic head is disclosed. The
magnetic head includes a first shield, a silicon seed layer
disposed over the first shield, and a metallic underlayer disposed
over the silicon seed layer. The metallic underlayer includes at
least a tantalum layer. The magnetic head further includes an
antiferromagnetic layer disposed over the metallic underlayer.
[0010] In another embodiment, a magnetic head is disclosed. The
magnetic head includes a first shield, a silicon seed layer
disposed over the first shield, and a metallic underlayer disposed
over the silicon seed layer. The metallic underlayer includes a
tantalum layer and a NiFe layer. The magnetic head further includes
an antiferromagnetic layer disposed over the metallic
underlayer.
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.
[0012] FIG. 1 illustrates an exemplary magnetic disk drive,
according to an embodiment of the invention.
[0013] FIG. 2 is a cross-sectional 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 a schematic cross-sectional view of portions of a
layer structure of a magnetic head.
[0015] FIG. 4 is a graph showing a relationship between the
thickness of a silicon seed layer and the magnetic field applied to
a pinned magnetic layer, according to various embodiments.
[0016] FIG. 5 is a graph showing a relationship between the
thickness of the silicon seed layer and the temperature at which
the magnetic field applied to the pinned magnetic layer is lost,
according to various embodiments.
[0017] 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
[0018] 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).
[0019] The embodiments of the present invention generally relate to
a magnetic head having a silicon seed layer disposed between a
lower shield and a metallic underlayer to enhance the
unidirectional anisotropy in an antiferromagnetic layer disposed
over the metallic underlayer.
[0020] 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, 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.
[0021] 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.
[0022] 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.
[0023] The magnetic read head 211 is a MR read head that includes a
MR sensing element 230 located between MR shields S1 and S2. 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.
[0024] 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.
[0025] 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. 2A. In one embodiment the distance between
the flare point 222 and the ABS is between about 30 nm and about
150 nm.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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 greatest thickness at a second distance (greater
than the first distance) from the ABS.
[0032] FIG. 3 is a schematic cross-sectional view of portions of a
layer structure 300 of the magnetic head 211 according to one
embodiment. The layer structure 300 includes a first shield layer
302 and a second shield layer 322, both comprising a magnetic
material. Suitable magnetic materials that may be utilized include
Ni, Fe, Co, NiFe, NiFeCo, NiCo, CoFe and combinations thereof.
[0033] Between the first and second shield layers 302, 322 is a
sensor structure 303. The sensor structure includes a silicon seed
layer 304, a metallic underlayer 310, an antiferromagnetic layer
312, a pinned magnetic layer 314, an interlayer 316, a free layer
318 and a capping layer 320. The metallic underlayer 310 may
enhance the crystallinity of the antiferromagnetic layer 312, which
helps achieving high unidirectional anisotropy induced from the
antiferromagnetic layer 312. However, if the metallic underlayer
310 is deposited on the first shield layer 302, the crystal
structure of the first shield layer 302 may affect the
antiferromagnetic layer 312 through the metallic underlayer 310,
causing difficulties in achieving sufficiently high degree of
unidirectional anisotropy. By placing the silicon seed layer 304
between the first shield layer 302 and the metallic underlayer 310,
high unidirectional anisotropy induced from the antiferromagnetic
layer 312 may be achieved. In addition, it has been found that the
temperature at which unidirectional anisotropy is lost is increased
with the addition of the silicon seed layer 304, which provides a
stable pinned magnetic layer 314 with respect to temperature.
[0034] The silicon seed layer 304 may be disposed over the first
shield layer 302 and may have a thickness ranging from about 0.2 nm
to about 1.0 nm. In one embodiment, the silicon seed layer 304 has
a thickness of about 0.6 nm. The metallic underlayer 310 may be
disposed over the silicon seed layer 304. The metallic underlayer
310 may be a multi-layer structure including a first sublayer 308
disposed on a second sublayer 306. The first sublayer 308 may be
made of a metal such as NiFe, NiCr, Ru, Cu, or combinations
thereof. The first sublayer 308 may have a thickness ranging from
about 1 nm to about 3 nm. The second sublayer 306 may be made of a
metal such as tantalum, hafnium, or alloys thereof and may have a
thickness ranging from about 0.5 nm to about 3.0 nm. In one
embodiment, the first sublayer 308 is made of NiFe and the second
sublayer 306 is made of tantalum.
[0035] The antiferromagnetic layer 312 may be disposed over the
metallic underlayer 310. The antiferromagnetic layer 312 may be
made of IrMn, PtMn, or the like and may have a thickness ranging
from about 4 nm to about 15 nm. Disposed over the antiferromagnetic
layer 312 is the pinned magnetic layer 314. The pinned magnetic
layer 314 may be a single layer made of a magnetic material such as
CoFe or the like and may have a thickness ranging from about 1 nm
to about 5 nm. Alternatively, the pinned magnetic layer 314 may be
a multi-layer structure. In one embodiment, the pinned magnetic
layer 314 has a first layer made of a magnetic material such as
CoFe, a second layer made of a magnetic material such as CoFe,
CoFeB, or the like, and a third layer made of a nonmagnetic
material sandwiched between the first layer and the second layer.
The first and second layers may each have a thickness ranging from
about 1 nm to about 5 nm. The third layer may include Ru, Rh, Ir,
Cu, or alloys thereof and may have a thickness ranging from about
0.4 nm to about 0.8 nm.
[0036] Disposed over the pinned magnetic layer 314 is the
interlayer 316. The interlayer 316 may be a tunnel barrier layer
including Al, Si, Mg, Ca, Sr, Zn, or the like. Alternatively, the
interlayer 316 may be a metal conducting layer including Cu, Al,
Ag, Sn, or the like. The free layer 318 may be disposed over the
interlayer 316. The free layer 318 may be a multi-layer structure
including a first layer made of a magnetic material such as CoFe or
the like and a second layer made of a magnetic material such as
NiFe or the like. The first and second layers each has a thickness
ranging from about 1 nm to about 5 nm. The capping layer 320 may
include a nonmagnetic material such as Ta, Ru, Ti, V, Cu, or the
like. The capping layer 320 may have a thickness ranging from about
0.5 nm to about 5.0 nm.
[0037] FIG. 4 is a graph 400 showing a relationship between the
thickness of the silicon seed layer 304 and the magnetic field
applied to the pinned magnetic layer 314, according to various
embodiments. As shown in the graph 400, the magnetic field is at
the lowest point when there is no silicon seed layer 304 (i.e.,
silicon thickness equals 0). Thus, with the silicon seed layer 304
(i.e., silicon thickness is greater than 0), a high unidirectional
anisotropic magnetic field may be obtained.
[0038] FIG. 5 is a graph 500 showing a relationship between the
thickness of the silicon seed layer 304 and the temperature at
which the magnetic field applied to the pinned magnetic layer 314
is lost, according to various embodiments. As shown in graph 500,
the temperature at which the magnetic field is lost is at the
lowest point when there is no silicon seed layer 304 (i.e., silicon
thickness equals 0). With the silicon seed layer 304 (i.e., silicon
thickness greater than 0), the pinned magnetic layer 314 may be
stable with respect to temperature.
[0039] In summary, by placing a silicon seed layer between a shield
and a metallic underlayer, a high unidirectional anisotropy in the
antiferromagnetic layer may be obtained. The silicon seed layer may
have a thickness ranging from about 0.2 nm to about 1 nm.
[0040] 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.
* * * * *