U.S. patent application number 14/160220 was filed with the patent office on 2014-07-10 for dual-imprint pattern for apparatus.
This patent application is currently assigned to SEAGATE TECHNOLOGY LLC. The applicant listed for this patent is SEAGATE TECHNOLOGY LLC. Invention is credited to David S. Kuo, Kim Y. Lee, Shih-fu Lee, Koichi Wago, Dieter K. Weller, Bing K. Yen.
Application Number | 20140193538 14/160220 |
Document ID | / |
Family ID | 51031713 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140193538 |
Kind Code |
A1 |
Lee; Kim Y. ; et
al. |
July 10, 2014 |
Dual-imprint pattern for apparatus
Abstract
Provided herein is an apparatus, including an imprint template
including a dual-imprint pattern, wherein the dual-imprint pattern
is characteristic of imprinting a first pattern on the template
with a first template and a second pattern on the template with a
second template, and wherein the first pattern and the second
pattern at least partially overlap to form the dual-imprint
pattern.
Inventors: |
Lee; Kim Y.; (Fremont,
CA) ; Yen; Bing K.; (Cupertino, CA) ; Kuo;
David S.; (Palo Alto, CA) ; Wago; Koichi;
(Sunnyvale, CA) ; Lee; Shih-fu; (Fremont, CA)
; Weller; Dieter K.; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEAGATE TECHNOLOGY LLC |
Cupertino |
CA |
US |
|
|
Assignee: |
SEAGATE TECHNOLOGY LLC
Cupertino
CA
|
Family ID: |
51031713 |
Appl. No.: |
14/160220 |
Filed: |
January 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12894640 |
Sep 30, 2010 |
|
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14160220 |
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Current U.S.
Class: |
425/385 |
Current CPC
Class: |
B29C 59/022 20130101;
G03F 7/0002 20130101 |
Class at
Publication: |
425/385 |
International
Class: |
B29C 59/02 20060101
B29C059/02 |
Claims
1-20. (canceled)
21. An apparatus, comprising: an imprint template comprising a
cross-hatched pattern, wherein the cross-hatched pattern is
characteristic of imprinting a first pattern on the template with a
first template and a second pattern on the template with a second
template, and wherein the first pattern and the second pattern at
least partially overlap to form the cross-hatched pattern; and a
backing plate bonded to the imprint template.
22. The apparatus of claim 21, wherein the first pattern comprises
a concentric line pattern.
23. The apparatus of claim 21, wherein the second pattern comprises
a radial line pattern.
24. The apparatus of claim 23, wherein the radial line pattern
comprises positive oblique radial lines, negative oblique radial
lines, or a combination thereof.
25. The apparatus of claim 21, wherein the cross-hatched pattern
comprises protruding features arranged in radial zones across the
imprint template.
26. The apparatus of claim 25, wherein the protruding features
maintain constant angular and radial pitch within each radial
zone.
27. An apparatus, comprising: an imprint template comprising a
cross-hatched pattern, wherein the cross-hatched pattern is
characteristic of imprinting a first pattern on the template with a
first template and a second pattern on the template with a second
template, and wherein the first pattern and the second pattern at
least partially overlap to form the cross-hatched pattern.
28. The apparatus of claim 27, wherein the first pattern comprises
a concentric line pattern, and wherein the second pattern comprises
a radial line pattern.
29. The apparatus of claim 28, wherein the second pattern comprises
a radial line pattern of positive oblique radial lines, negative
oblique radial lines, or a combination thereof.
30. The apparatus of claim 28, wherein the cross-hatched pattern
comprises protruding features arranged in radial zones across the
imprint template.
31. The apparatus of claim 30, wherein the protruding features
maintain constant angular and radial pitch within each radial
zone.
32. The apparatus of claim 30, wherein the density of protruding
features is about the same in each radial zone.
33. An apparatus, comprising: an imprint template comprising a
dual-imprint pattern, wherein the dual-imprint pattern is
characteristic of imprinting a first pattern on the template with a
first template and a second pattern on the template with a second
template, and wherein the first pattern and the second pattern at
least partially overlap to form the dual-imprint pattern.
34. The apparatus of claim 33, wherein the dual-imprint pattern
comprises a cross-hatched pattern.
35. The apparatus of claim 33, wherein the first pattern comprises
a concentric line pattern.
36. The apparatus of claim 33, wherein the second pattern comprises
a radial line pattern.
37. The apparatus of claim 33, wherein the dual-imprint pattern
comprises protruding features arranged in radial zones across the
imprint template.
38. The apparatus of claim 37, wherein the protruding features
maintain constant angular and radial pitch within each radial zone,
and wherein the density of protruding features is about the same in
each radial zone.
39. The apparatus of claim 33, wherein the dual-imprint pattern
comprises protruding features skewed at inner and outer dimensions
of the imprint template to accommodate head skew effects in
corresponding patterned recording media of data storage
devices.
40. The apparatus of claim 33, further comprising a backing plate,
wherein the imprint template is characteristic of a mandrel slice,
and wherein the mandrel slice is bonded to the backing plate.
Description
FIELD
[0001] Embodiments according to the present invention generally
relate to imprint lithography.
BACKGROUND
[0002] Micro-fabrication involves the fabrication of very small
structures, for example structures having features on the order of
micro-meters or smaller. Lithography is a micro-fabrication
technique used to create ultra-fine (sub-25 nm) patterns in thin
film on a substrate. During imprint lithography, a mold having at
least one protruding feature is pressed into the thin film. The
protruding feature in the mold creates a recess in the thin film,
thus creating an image of the mold. The thin film retains the image
as the mold is removed. The mold may be used to imprint multiple
thin films on different substrates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Embodiments of the present invention are illustrated by way
of example, and not by way of limitation, in the figures of the
accompanying drawings.
[0004] FIG. 1 is a top view of a template with concentric grooves
according to an embodiment of the present invention.
[0005] FIG. 2 is a perspective view of a concentric line template
at an early stage of manufacture according to an embodiment of the
present invention.
[0006] FIG. 3 is a perspective view of the concentric line template
after first layers and second layers have been deposited according
to an embodiment of the present invention.
[0007] FIG. 4 is a perspective view of the concentric line template
after dicing according to an embodiment of the present
invention.
[0008] FIG. 5 is a perspective view of the concentric line template
after bonding according to an embodiment of the present
invention.
[0009] FIG. 6 is a perspective view of the concentric line template
after etching according to an embodiment of the present
invention.
[0010] FIG. 7 is a simplified cross-sectional view of a line
pattern at an early stage of manufacture according to an embodiment
of the present invention.
[0011] FIG. 8 is a simplified cross-sectional view of the line
pattern after sidewall formation according to an embodiment of the
present invention.
[0012] FIG. 9 is a simplified cross-sectional view of the line
pattern after resist removal according to an embodiment of the
present invention.
[0013] FIG. 10 is a simplified cross-sectional view of the line
pattern after space filling according to an embodiment of the
present invention.
[0014] FIG. 11 is a simplified cross-sectional view of a line
pattern at an early stage of manufacture according to an embodiment
of the present invention.
[0015] FIG. 12 is a simplified cross-sectional view of the line
pattern after first sidewall formation according to an embodiment
of the present invention.
[0016] FIG. 13 is a simplified cross-sectional view of the line
pattern after resist removal according to an embodiment of the
present invention.
[0017] FIG. 14 is a simplified cross-sectional view of the line
pattern after second sidewall formation according to an embodiment
of the present invention.
[0018] FIG. 15 is a simplified cross-sectional view of the line
pattern after first sidewall removal according to an embodiment of
the present invention.
[0019] FIG. 16 is a simplified cross-sectional view of the line
pattern after space filling according to an embodiment of the
present invention.
[0020] FIG. 17 is a simplified plan view of a portion of a
substrate undergoing multi-step imprinting at an early stage of
manufacture according to an embodiment of the present
invention.
[0021] FIG. 18 is a simplified plan view of the substrate after
radial line imprinting, according to an embodiment of the present
invention.
[0022] FIG. 19 is a data storage device in which embodiments of the
present invention can be implemented to form bit-patterned
media.
[0023] FIG. 20 is a simplified cross-sectional view of a
perpendicular magnetic recording medium, which may be used for the
data storage disc (FIG. 19).
[0024] FIG. 21 is a simplified cross-sectional view of a portion of
the perpendicular magnetic recording medium with a head unit.
[0025] FIG. 22 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disc (FIG. 19) during manufacture.
[0026] FIG. 23 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disc (FIG. 19) during manufacture.
[0027] FIG. 24 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disc (FIG. 19) during manufacture.
[0028] FIG. 25 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disc (FIG. 19) during manufacture.
[0029] FIG. 26 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disk (FIG. 19) during manufacture.
[0030] FIG. 27 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template according to an
embodiment of the present invention, which may be used to imprint
the data storage disk (FIG. 19) during manufacture.
[0031] FIG. 28 depicts a flowchart of an exemplary method of
imprint lithography according to an embodiment of the present
invention.
DETAILED DESCRIPTION
[0032] Reference will now be made in detail to embodiments,
examples of which are illustrated in the accompanying drawings.
While the embodiments will be described in conjunction with the
drawings, it will be understood that they are not intended to limit
the embodiments. On the contrary, the embodiments are intended to
cover alternatives, modifications and equivalents. Furthermore, in
the following detailed description, numerous specific details are
set forth in order to provide a thorough understanding. However, it
will be recognized by one of ordinary skill in the art that the
embodiments may be practiced without these specific details. In
other instances, well-known methods, procedures, components, and
circuits have not been described in detail as not to unnecessarily
obscure aspects of the embodiments.
[0033] For expository purposes, the term "horizontal" as used
herein refers to a plane parallel to the plane or surface of a
substrate, regardless of its orientation. The term "vertical"
refers to a direction perpendicular to the horizontal as just
defined. Terms such as "above," "below," "bottom," "top," "side,"
"higher," "lower," "upper," "over," and "under" are referred to
with respect to the horizontal plane.
[0034] FIG. 1 is a top view of a template 100 with concentric
grooves 102 according to an embodiment of the present invention.
The concentric grooves 102 may be produced by thin film deposition
(See FIG. 2-FIG. 6) or by nano imprint lithography using frequency
doubling (See FIG. 7-FIG. 16).
[0035] FIG. 2 is a perspective view of a concentric line template
200 at an early stage of manufacture according to an embodiment of
the present invention. In an embodiment, the concentric line
template 200 is the template 100 (See FIG. 1) with the concentric
grooves 102 (See FIG. 1). A mandrel 202 is rotatable by a device,
not shown.
[0036] FIG. 3 is a perspective view of the concentric line template
200 after first layers 302 and second layers 304 have been
deposited according to an embodiment of the present invention. In
order to deposit the first layers 302 and the second layers 304,
the mandrel 202 is rotated and the first layers 302 and the second
layers 304 are sequentially deposited. For example, first layer 302
is deposited on the mandrel 202. Second layer 304 is deposited on
first layer 302. First layer 302 is deposited on second layer 304.
Alternately depositing the first layers 302 and the second layers
304 is repeated until a predetermined number of layers are
deposited.
[0037] The first layers 302 and the second layers 304 are deposited
using thin film deposition techniques. Thus, the first layers 302
and the second layers 304 may be made very thin, for example less
than or equal to 2 nm in thickness each. In addition, the first
layers 302 may be a first material and the second layers 304 may be
a second material. The first material and the second material may
be of different metals or non-metals that allow for preferential
removal. Thus, the first layers 302 or the second layers 304 may be
removed with the other layers remaining. For example, in an
embodiment the first layers 302 may be removed by etching and the
second layers 304 will remain.
[0038] FIG. 4 is a perspective view of the concentric line template
200 after dicing according to an embodiment of the present
invention. The mandrel 202, the first layers 302, and the second
layers 304 are diced into a thin slice 402. In an embodiment,
convention dicing methodology dices into a plurality of thin
slices.
[0039] FIG. 5 is a perspective view of the concentric line template
200 after bonding according to an embodiment of the present
invention. The thin slice 402 is bonded to a backing plate 502. In
an embodiment, the thin slice 402 is polished after it is bonded to
the backing plate 502.
[0040] FIG. 6 is a perspective view of the concentric line template
200 after etching according to an embodiment of the present
invention. A preferential dry or wet etch has removed the first
layers 302 (FIG. 5). The mandrel 202 and the second layers 304 of
the thin slice 402 remain bonded to the backing plate 502. Removal
of the first layers 302 (FIG. 5) forms concentric circular grooves
602 that are shaped by the second layers 304. The concentric
circular grooves 602 and the second layers 304 form a concentric
line pattern 604. The concentric line pattern 604 may serve as a
template in subsequent processing below. In an alternate embodiment
the preferential etch removes the second layers 304, and the first
layers 302 (FIG. 5) remain.
[0041] FIG. 7 is a simplified cross-sectional view of a line
pattern 700 undergoing frequency increasing at an early stage of
manufacture according to an embodiment of the present invention.
Frequency increasing is used to increase the frequency of line
patterns. For example, in an embodiment frequency increasing may be
used to double the frequency of the second layers 304 (FIG. 6) and
the concentric circular grooves 602 (FIG. 6) of the concentric line
pattern 604 (FIG. 6).
[0042] Resist areas 702 have been formed on a substrate 704, for
example by lithographic processes or thin film deposition (FIG. 6).
The resist areas 702 border first spaces 706 therebetween. The
resist areas 702 form a form a resist pattern with a land to pitch
ratio of 1/4.
[0043] FIG. 8 is a simplified cross-sectional view of the line
pattern 700 after sidewall formation according to an embodiment of
the present invention. Sidewalls 802 have been formed on the
substrate 704 and the sides of the resist areas 702.
[0044] In an embodiment, the sidewalls 802 are formed by first
depositing sidewall material on the resist areas 702 and in the
first spaces 706 on the substrate 704. For example the sidewall
material may be deposited by chemical vapor deposition ("CVD"), and
the sidewall material may be a dielectric material, for example
SiN. Other materials, including other dielectric materials, may be
used as the sidewall material without departing from the
embodiments of the invention.
[0045] After the sidewall material has been deposited, sidewall
material is removed from the top of the resist areas 702. In
addition, a portion of the sidewall material is removed from the
first spaces 706, thus forming the sidewalls 802 on the sides of
the resist areas 702. For example, reactive ion etching ("RIE") can
be used to anistropically etch the sidewall material to form the
sidewalls 802. In an embodiment, the width of the sidewalls 802 is
1/4 the pitch, e.g. the same as the width of the resist areas
702.
[0046] FIG. 9 is a simplified cross-sectional view of the line
pattern 700 after resist removal according to an embodiment of the
present invention. The resist areas 702 (FIG. 8) have been removed,
for example by anisotropic etching, thus forming second spaces
902.
[0047] FIG. 10 is a simplified cross-sectional view of the line
pattern 700 after space filling according to an embodiment of the
present invention. The first spaces 706 (FIG. 9) and the second
spaces 902 (FIG. 9) have been filled with a conductive material
1002, for example Ni, having a width 1/4 the pitch. For example,
electroplating may be used to fill the first spaces 706 (FIG. 9)
and the second spaces 902 (FIG. 9). Thus, the line frequency of the
line pattern 700 has doubled.
[0048] FIG. 11 is a simplified cross-sectional view of a line
pattern 1100 at an early stage of manufacture according to an
embodiment of the present invention. The frequency increasing is
used to increase the frequency of line patterns. For example, in an
embodiment frequency increasing may be used to quadruple the
frequency of the second layers 304 (FIG. 6) and the concentric
circular grooves 602 (FIG. 6) of the concentric line pattern 604
(FIG. 6).
[0049] Resist areas 1102 have been formed on a substrate 1104, for
example by lithographic processes or thin film deposition (FIG. 6).
The resist areas 1102 border first spaces 1106 therebetween. The
resist areas 1102 form a resist pattern with a land to pitch ratio
of 3/8.
[0050] FIG. 12 is a simplified cross-sectional view of the line
pattern 1100 after first sidewall formation according to an
embodiment of the present invention. First sidewalls 1202 have been
formed on the substrate 1104 and the sides of the resist areas
1102, for example by lithographic processes.
[0051] In an embodiment the first sidewalls 1202 are formed by
first depositing sidewall material on the resist areas 1102 and in
the first spaces 1106 on the substrate 1104. For example the
sidewall material may be deposited by chemical vapor deposition
("CVD"), and the sidewall material may be a dielectric material,
for example SiN. Other materials, including other dielectric
materials, may be used as the sidewall material without departing
from the embodiments of the invention.
[0052] After the sidewall material has been deposited, sidewall
material is removed from the top of the resist areas 1102. In
addition, a portion of the sidewall material is removed from the
first spaces 1106, thus forming the first sidewalls 1202 on the
sides of the resist areas 1102. For example, reactive ion etching
("RIE") can be used to anistropically etch the sidewall material to
form the first sidewalls 1202. In an embodiment, the width of the
first sidewalls 1202 is 1/8 the pitch.
[0053] FIG. 13 is a simplified cross-sectional view of the line
pattern 1100 after resist removal according to an embodiment of the
present invention. The resist areas 1102 (FIG. 12) have been
removed, for example by anisotropic etching, thus forming second
spaces 1302.
[0054] FIG. 14 is a simplified cross-sectional view of the line
pattern 1100 after second sidewall formation according to an
embodiment of the present invention. Second sidewalls 1402 have
been formed on the substrate 1104 and the sides of the first
sidewalls 1202.
[0055] In an embodiment, the second sidewalls 1402 are formed by
first depositing sidewall material on the first sidewalls 1202, in
the first spaces 1106, in the second spaces 1302, and on the
substrate 1104. For example the sidewall material may be deposited
by chemical vapor deposition ("CVD"). In an embodiment, the second
sidewall material is different from the first sidewall material.
Thus, one set of sidewalls may be preferentially removed without
removing the other set of sidewalls. For example, the first
sidewalls 1202 may consist of SiN and the second sidewalls 1402 may
be SiO.sub.2. Other materials, including other dielectric
materials, may be used as the sidewall material without departing
from the embodiments of the invention.
[0056] After the second sidewall material has been deposited,
second sidewall material is removed from the top of the first
sidewalls 1202. In addition, a portion of the second sidewall
material is removed from the first spaces 1106 and the second
spaces 1302, thus forming the second sidewalls 1402 on the sides of
the first sidewalls 1202. For example, reactive ion etching ("RIE")
can be used to anistropically etch the second sidewall material to
form the second sidewalls 1402. In an embodiment, the width of the
second sidewalls 1402 is 1/8 the pitch.
[0057] FIG. 15 is a simplified cross-sectional view of the line
pattern 1100 after first sidewall removal according to an
embodiment of the present invention. The first sidewalls 1202 (FIG.
14) have been selectively removed, for example by etching, leaving
the second sidewalls 1402 and a plurality of spaces 1502 between
the second sidewalls 1402.
[0058] FIG. 16 is a simplified cross-sectional view of the line
pattern 1100 after space filling according to an embodiment of the
present invention. The plurality of spaces 1502 (FIG. 15) have been
filled with a conductive material 1602, for example Ni, having a
width 1/8 the pitch. For example, electroplating may be used to
fill the plurality of spaces 1502 (FIG. 15). Thus, the line
frequency of the line pattern 1100 has quadrupled.
[0059] The thin film deposition and the frequency increasing may be
used to create templates of periodic arrays of very small and
uniform dots. The individual dot geometry may exhibit a variety of
shapes, such as round, square, diamond, etc. The dot array forms a
periodic structure, similar to the lattice in a single crystal, in
a two-dimensional plane.
[0060] FIG. 17 is a simplified plan view of a portion of a
substrate 1700 undergoing multi-step imprinting at an early stage
of manufacture according to an embodiment of the present invention.
A concentric line pattern 1702 has been imprinted in the substrate
1700 using a first template (not shown) formed by thin film
deposition (FIG. 6). In an embodiment, frequency increasing,
described above, may have been used to increase the frequency of
the concentric line pattern on the template.
[0061] FIG. 18 is a simplified plan view of the substrate 1700
after radial line imprinting, according to an embodiment of the
present invention. A radial line pattern 1802 has been imprinted in
the substrate 1700 using a second template (not shown). The radial
line pattern 1802 at least partially overlaps the concentric line
pattern 1702 and is arranged at an oblique angle to the substrate
1700. The radial line pattern 1802 may have been formed in the
second template, for example, by e-beam lithography. In an
embodiment, frequency increasing, described above, may have been
used to increase the frequency of the radial line pattern on the
second template.
[0062] Thus, multi-step imprinting has formed a third pattern 1804
on the substrate 1700. The third pattern 1804 is a high resolution
cross-hatched pattern that can be used as a template in further
processing.
[0063] Magnetic storage media are widely used in various
applications, particularly in the computer industry for data
storage and retrieval applications, as well as for storage of audio
and video signals. Perpendicular magnetic recording media, for
example hard disc drive storage devices, include recording media
with a perpendicular anisotropy in the magnetic layer. In
perpendicular magnetic recording media, residual magnetization is
formed in a direction perpendicular to the surface of the magnetic
medium, typically by a layer of a magnetic material on a
substrate.
[0064] A perpendicular recording disc drive head typically includes
a trailing write pole, and a leading return or opposing pole
magnetically coupled to the write pole. In addition, an
electrically conductive magnetizing coil surrounds the yoke of the
write pole. During operation, the recording head flies above the
magnetic recording medium by a distance referred to as the fly
height. To write to the magnetic recording medium, the magnetic
recording medium is moved past the recording head so that the
recording head follows the tracks of the magnetic recording medium,
with the magnetic recording medium first passing under the return
pole and then passing under the write pole. Current is passed
through the coil to create magnetic flux within the write pole. The
magnetic flux passes from the write pole tip, through the hard
magnetic recording track, into the soft underlayer, and across to
the return pole. In addition to providing a return path for the
magnetic flux, the soft underlayer produces magnetic charge images
of the magnetic recording layer, increasing the magnetic flux and
increasing the playback signal. The current can be reversed,
thereby reversing the magnetic field and reorienting the magnetic
dipoles.
[0065] The perpendicular recording medium is a continuous layer of
discrete, contiguous magnetic crystals or domains. Within the
continuous magnetic layer, discrete information is stored in
individual bits. The individual bits are magnetically oriented
positively or negatively, to store binary information. The number
of individual bits on the recording medium is a function of the
areal density. As areal densities increase, the amount of
information stored on the recording medium also increases.
Manufacturers strive to satisfy the ever-increasing consumer demand
for higher capacity hard drives by increasing the areal
density.
[0066] High density perpendicular recording media use carefully
balanced magnetic properties. These carefully balanced magnetic
properties include sufficiently high anisotropy (perpendicular
magnetic orientation) to ensure thermal stability, resist erasure,
and function effectively with modern disc drive head designs; and
grain-to-grain uniformity of magnetic properties sufficient to
maintain thermal stability and minimum switching field distribution
(SFD).
[0067] As recording densities increase, smaller grain structures
help to maintain the number of magnetic particles in a bit at a
similar value. Smaller grain structures are easier to erase,
requiring higher anisotropy to maintain thermal stability, and
making writability worse. Further, when individual storage bits
within magnetic layers of magnetic recording media are reduced in
size, they store less energy making it easier for the bits to lose
information. Also, as individual weaker bits are placed closer
together, it is easier for continuous read/write processes and
operating environments to create interference within and between
the bits. This interference disrupts the read/write operations,
resulting in data loss.
[0068] The magnetic layers are designed as an ordered array of
uniform islands, each island storing an individual bit. This is
referred to as bit patterned media. By eliminating the continuous
magnetic layer and restricting the bits to discrete magnetic
islands, interference is reduced and areal densities are increased.
However, high areal density bit patterned media (e.g., >500
Gbpsi) demands high anisotropy of the magnetic material in the
islands.
[0069] Methods and media structures are described herein, which
embodiments of the present invention as described above, optimize
anisotropy for bit patterned magnetic recording media. It is
appreciated that magnetic recording media as discussed herein may
be utilized with a variety of systems including disc drive memory
systems, etc.
[0070] FIG. 19 is a data storage device in which embodiments of the
present invention can be implemented to form bit-patterned media.
FIG. 19 is a plan view of an exemplary disc drive 1900. The disc
drive 1900 generally includes a base plate 1902 and a cover (not
shown) that may be disposed on the base plate 1902 to define an
enclosed housing for various disc drive components. The disc drive
1900 includes one or more data storage discs 1904 of
computer-readable data storage media. Typically, both of the major
surfaces of each data storage disc 1904 include a plurality of
concentrically disposed tracks for data storage purposes. Each data
storage disc 1904 is mounted on a hub or spindle 1906, which in
turn is rotatably interconnected with the base plate 1902 and/or
cover. Multiple data storage discs 1904 are typically mounted in
vertically spaced and parallel relation on the spindle 1906. A
spindle motor 1908 rotates the data storage discs 1904 at an
appropriate rate.
[0071] The disc drive 1900 also includes an actuator arm assembly
1910 that pivots about a pivot bearing 1912, which in turn is
rotatably supported by the base plate 1902 and/or cover. The
actuator arm assembly 1910 includes one or more individual rigid
actuator arms 1914 that extend out from near the pivot bearing
1912. Multiple actuator arms 1914 are typically disposed in
vertically spaced relation, with one actuator arm 1914 being
provided for each major data storage surface of each data storage
disc 1904 of the disc drive 1900. Other types of actuator arm
assembly configurations could be utilized as well, such as an "E"
block having one or more rigid actuator arm tips or the like that
cantilever from a common structure. Movement of the actuator arm
assembly 1910 is provided by an actuator arm drive assembly, such
as a voice coil motor 1916 or the like. The voice coil motor 1916
is a magnetic assembly that controls the operation of the actuator
arm assembly 1910 under the direction of control electronics
1918.
[0072] A load beam or suspension 1920 is attached to the free end
of each actuator arm 1914 and cantilevers therefrom. Typically, the
suspension 1920 is biased generally toward its corresponding data
storage disc 1904 by a spring-like force. A slider 1922 is disposed
at or near the free end of each suspension 1920. What is commonly
referred to as the read/write head (e.g., transducer) is
appropriately mounted as a head unit (not shown) under the slider
1922 and is used in disc drive read/write operations. The head unit
under the slider 1922 may utilize various types of read sensor
technologies such as anisotropic magnetoresistive (AMR), giant
magnetoresistive (GMR), tunneling magnetoresistive (TuMR), other
magnetoresistive technologies, or other suitable technologies.
[0073] The head unit under the slider 1922 is connected to a
preamplifier 1926, which is interconnected with the control
electronics 1918 of the disc drive 1900 by a flex cable 1928 that
is typically mounted on the actuator arm assembly 1910. Signals are
exchanged between the head unit and its corresponding data storage
disc 1904 for disc drive read/write operations. In this regard, the
voice coil motor 1916 is utilized to pivot the actuator arm
assembly 1910 to simultaneously move the slider 1922 along a path
1930 and across the corresponding data storage disc 1904 to
position the head unit at the appropriate position on the data
storage disc 1904 for disc drive read/write operations.
[0074] When the disc drive 1900 is not in operation, the actuator
arm assembly 1910 is pivoted to a "parked position" to dispose each
slider 1922 generally at or beyond a perimeter of its corresponding
data storage disc 1904, but in any case in vertically spaced
relation to its corresponding data storage disc 1904. In this
regard, the disc drive 1900 includes a ramp assembly 1932 that is
disposed beyond a perimeter of the data storage disc 1904 to both
move the corresponding slider 1922 vertically away from its
corresponding data storage disc 1904 and to also exert somewhat of
a retaining force on the actuator arm assembly 1910.
[0075] FIG. 20 is a simplified cross-sectional view of a
perpendicular magnetic recording medium 2000, which may be used for
the data storage disc 1904 (FIG. 19). The perpendicular magnetic
recording medium 2000 is an apparatus including multiple layers
established upon a substrate 2002. A seed layer 2008 is a layer
that is established overlying the substrate. A base layer 2010 is a
layer that is established overlying the seed layer 2008.
Perpendicular magnetic recording islands 2012 are recording areas
that are established in the base layer 2010 and on the seed layer
2008.
[0076] The substrate 2002 can be fabricated from materials known to
those skilled in the art to be useful for magnetic recording media
for hard disc storage devices. For example, the substrate 2002 may
be fabricated from aluminum (Al) coated with a layer of nickel
phosphorous (NiP). However, it will be appreciated that the
substrate 2002 can also be fabricated from other materials such as
glass and glass-containing materials, including glass-ceramics. The
substrate 2002 may have a smooth surface upon which the remaining
layers can be deposited.
[0077] In a further embodiment, a buffer layer 2004 is established
overlying the substrate 2002, a soft underlayer 2006 is established
overlying the buffer layer 2004, and the seed layer 2008 is
overlying the soft underlayer 2006. The buffer layer 2004 can be
established from elements such as Tantalum (Ta). The soft
underlayer 2006 can be established from soft magnetic materials
such as CoZrNb, CoZrTa, FeCoB and FeTaC. The soft underlayer 2006
can be formed with a high permeability and a low coercivity. For
example, in an embodiment the soft underlayer 2006 has a coercivity
of not greater than about 10 oersteds (Oe) and a magnetic
permeability of at least about 50. The soft underlayer 2006 may
comprise a single soft underlayer or multiple soft underlayers, and
may be separated by spacers. If multiple soft underlayers are
present, the soft underlayers can be fabricated from the same soft
magnetic material or from different soft magnetic materials.
[0078] In the embodiment illustrated, the seed layer 2008 is
disposed on the soft underlayer 2006. The seed layer 2008 can be
established, for example, by physical vapor deposition (PVD) or
chemical vapor deposition (CVD) from noble metal materials such as,
for example, Ru, Ir, Pd, Pt, Os, Rh, Au, Ag or other alloys. The
use of these materials results in desired growth properties of the
perpendicular magnetic recording islands 2012.
[0079] The perpendicular magnetic recording islands 2012 as
described herein may be formed within the base layer 2010 and on
the seed layer 2008 according to the embodiments of the present
invention. The perpendicular magnetic recording islands 2012 can be
established to have an easy magnetization axis (e.g., the C-axis)
that is oriented perpendicular to the surface of the perpendicular
magnetic recording medium 2000. Useful materials for the
perpendicular magnetic recording islands 2012 include cobalt-based
alloys with a hexagonal close packed (hcp) structure. Cobalt can be
alloyed with elements such as chromium (Cr), platinum (Pt), boron
(B), niobium (Nb), tungsten (W) and tantalum (Ta).
[0080] The perpendicular magnetic recording medium 2000 can also
include a protective layer (not shown) on top of the perpendicular
magnetic recording islands 2012 and/or the base layer 2010, such as
a protective carbon layer, and a lubricant layer disposed over the
protective layer. These layers are adapted to reduce damage from
the read/write head interactions with the recording medium during
start/stop operations.
[0081] FIG. 21 is a simplified cross-sectional view of a portion of
the perpendicular magnetic recording medium 2000 with a head unit
2100. During the writing process, a perpendicular write head 2102
flies or floats above the perpendicular magnetic recording medium
2000. The perpendicular write head 2102 includes a write pole 2104
coupled to an auxiliary pole 2106. The arrows shown indicate the
path of a magnetic flux 2108, which emanates from the write pole
2104 of the perpendicular write head 2102, entering and passing
through at least one perpendicular magnetic recording island 2012
in the region below the write pole 2104, and entering and traveling
within the soft underlayer 2006 for a distance. The magnetically
soft underlayer 2006 serves to guide magnetic flux emanating from
the head unit 2100 through the recording island 2012, and enhances
writability. As the magnetic flux 2108 travels towards and returns
to the auxiliary pole 2106, the magnetic flux 2108 disperses.
[0082] The magnetic flux 2108 is concentrated at the write pole
2104, and causes the perpendicular magnetic recording island 2012
under the write pole 2104 to magnetically align according to the
input from the write pole 2104. As the magnetic flux 2108 returns
to the auxiliary pole 2106 and disperses, the magnetic flux 2108
may again encounter one or more perpendicular magnetic recording
islands 2012. However, the magnetic flux 2108 is no longer
concentrated and passes through the perpendicular magnetic
recording islands 2012, without detrimentally affecting the
magnetic alignment of the perpendicular magnetic recording islands
2012.
[0083] FIG. 22 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2200 according to
an embodiment of the present invention, which may be used to
imprint the data storage disc 1904 (FIG. 19) during manufacture.
The perpendicular magnetic recording medium template 2200 has been
fabricated by dual imprinting. Concentric line features 2202 have
been imprinted with a concentric line template (not shown). In an
embodiment, the concentric line template may be fabricated by thin
film deposition (FIG. 6). In addition, positive radial line
features 2204 have been imprinted with a positive oblique radial
line template (not shown). In an embodiment, the line features on
the concentric line template and the positive oblique radial line
template have had the line density increased by frequency
increasing (FIG. 10 or FIG. 16).
[0084] Thus, the concentric line features 2202 and the positive
radial line features 2204 form a staggered array 2206 in the
perpendicular magnetic recording medium template 2200. The
staggered array 2206 in the perpendicular magnetic recording medium
template 2200 may be used to form the perpendicular magnetic
recording islands 2012 (FIG. 20). Furthermore in an alternate
embodiment (not shown), a radial line template may have a line
arrangement that forms an aligned array in a perpendicular magnetic
recording medium template.
[0085] FIG. 23 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2300 according to
an embodiment of the present invention, which may be used to
imprint the data storage disc 1904 (FIG. 19) during manufacture.
The perpendicular magnetic recording medium template 2300 has been
fabricated by dual imprinting. Concentric line features 2302 have
been imprinted with a concentric line template (not shown). In an
embodiment, the concentric line template may be fabricated by thin
film deposition (FIG. 6). In addition, negative radial line
features 2304 have been imprinted with a negative oblique radial
line template (not shown). In an embodiment, the line features on
the concentric line template and the negative oblique radial line
template have had the line density increased by the frequency
increasing (FIG. 10 or FIG. 16).
[0086] Thus, the concentric line features 2302 and the negative
radial line features 2304 form a staggered array 2306 in the
perpendicular magnetic recording medium template 2300. The
staggered array 2306 in the perpendicular magnetic recording medium
template 2300 may be used to form the perpendicular magnetic
recording islands 2012 (FIG. 20).
[0087] FIG. 24 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2400 according to
an embodiment of the present invention, which may be used to
imprint the data storage disc 1904 (FIG. 19) during manufacture.
The perpendicular magnetic recording medium template 2400 has been
fabricated by dual imprinting. Positive radial line features 2402
have been imprinted with a positive oblique radial line template
(not shown). In addition, negative radial line features 2404 have
been imprinted with a negative oblique radial line template (not
shown). In an embodiment, the line features on the positive oblique
radial line template and the negative oblique radial line template
have had the line density increased by frequency increasing (FIG.
10 or FIG. 16).
[0088] Thus, the positive radial line features 2402 and the
negative radial line features 2404 form a staggered array 2406 in
the perpendicular magnetic recording medium template 2400. The
staggered array 2406 in the perpendicular magnetic recording medium
template 2400 may be used to form the perpendicular magnetic
recording islands 2012 (FIG. 20).
[0089] FIG. 25 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2500 according to
an embodiment of the present invention, which may be used to
imprint the data storage disc 1904 (FIG. 19) during manufacture. In
an embodiment, the perpendicular magnetic recording medium template
2500 has been divided into a first radial zone 2502, a second
radial zone 2504, and a third radial zone 2506. In alternate
embodiments, any number of radial zones may be used.
[0090] In an embodiment, different concentric line templates and/or
radial line templates are used to imprint the first radial zone
2502, the second radial zone 2504, and the third radial zone 2506.
The templates are selected such that within each zone, array
density maintains constant angular and radial pitch. As a result,
array density within a zone decreases as radius increases.
Therefore in an embodiment, the angular pitch of each zone is
adjusted to maintain an array density that is nearly the same as
the previous zone.
[0091] FIG. 26 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2600 according to
an embodiment of the present invention, which may be used to
imprint the data storage disk 1904 (FIG. 19) during manufacture. As
a head 2602 traverses a bit arrangement in the downtrack direction,
the head 2602 experiences different head skew effects at different
radial zones of a disk.
[0092] In an embodiment, an array 2604 is skewed to accommodate the
head skew effects at an outer dimension of a disk. An oblique line
pattern 2606 has an angle design as a function of the skew angle
that occurs at different radii. Thus, the oblique line pattern 2606
is varied to have different angles as a function of the skew
angle.
[0093] FIG. 27 is a simplified plan view of a portion of a
perpendicular magnetic recording medium template 2700 according to
an embodiment of the present invention, which may be used to
imprint the data storage disk 1904 (FIG. 19) during manufacture. In
an embodiment, an array 2704 is skewed to accommodate the head skew
effects at an inner dimension of a disk.
[0094] FIG. 28 depicts a flowchart 2800 of an exemplary method of
imprint lithography according to an embodiment of the present
invention. Although specific steps are disclosed in the flowchart,
such steps are exemplary. That is, embodiments of the present
invention are well-suited to performing various other steps or
variations of the steps recited in the flowchart.
[0095] In block 2802, a first pattern is formed on a first
template. For example, in FIG. 6 a concentric line pattern has been
formed on a template by thin film deposition.
[0096] In block 2804, a second pattern is formed on a second
template. For example, in FIG. 22 the radial line template used was
a positive oblique radial line template with positive radial line
features. However, in FIG. 23 the radial line template used was a
negative oblique radial line template with negative radial line
features.
[0097] In block 2806, line frequency is increased on the first
template and/or the second template by frequency increasing. For
example, in FIG. 16 frequency increasing has increased the line
frequency of a line pattern. In FIG. 17 frequency increasing was
used to increase the line density of the first concentric line
pattern on the template. In FIG. 18 frequency increasing was used
to increase the line density of the second radial line pattern on
the template.
[0098] In block 2808, the first pattern is imprinted with the first
template on a first substrate of a lithographic template. For
example, in FIG. 22 a first concentric line pattern template was
used to form a concentric line pattern on a perpendicular magnetic
recording media template.
[0099] In block 2810, the second pattern is imprinted with the
second template on the substrate of the lithographic template. The
first pattern and the second pattern at least partially overlap,
and the first pattern and the second pattern form a third pattern.
For example, in FIG. 22 a second radial line pattern template was
used to transfer a radial line pattern to the perpendicular
magnetic recording media template. The first concentric line
pattern and the second radial line pattern partially overlap, thus
forming a third pattern on the perpendicular magnetic recording
media template. In an alternate embodiment the radial line pattern
is formed first and the concentric line pattern is formed
second.
[0100] In a block 2812, the third pattern is formed on a first
radial zone on a second substrate with the lithographic template.
For example, in FIG. 25 a perpendicular magnetic recording medium
has been divided into radial zones. The perpendicular magnetic
recording media template imprints the third pattern in the first
zone on the perpendicular magnetic recording media. In an
embodiment, the third pattern lithographically forms perpendicular
magnetic recording islands on the perpendicular magnetic recording
media.
[0101] In a block 2814, a fourth pattern is formed on a second
radial zone on the second substrate. In an embodiment, the fourth
pattern is formed with a second lithographic template, however in
an alternate embodiment the fourth pattern may be formed on the
first lithographic template. For example, in FIG. 25 the second
radial zone may be imprinted with a fourth pattern that has been
formed on a second lithographic template. In an embodiment, the
fourth pattern lithographically forms perpendicular magnetic
recording islands on the perpendicular magnetic recording
media.
[0102] In addition, in an embodiment the third pattern and/or the
fourth pattern may be skewed to accommodate head skew effects. For
example, in FIG. 26 the pattern has been skewed to accommodate the
head skew effects experienced by the head.
[0103] The foregoing description, for purpose of explanation, has
been described with reference to specific embodiments. However, the
illustrative discussions above are not intended to be exhaustive or
to limit the invention to the precise forms disclosed. Many
modifications and variations are possible in view of the above
teachings. The embodiments were chosen and described in order to
best explain the principles of the invention and its practical
applications, to thereby enable others skilled in the art to best
utilize the invention and various embodiments with various
modifications as may be suited to the particular use
contemplated.
* * * * *