U.S. patent application number 13/064463 was filed with the patent office on 2011-10-20 for magnetic recording medium and method of manufacturing the same.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Hiroyuki Hieda.
Application Number | 20110255193 13/064463 |
Document ID | / |
Family ID | 44788023 |
Filed Date | 2011-10-20 |
United States Patent
Application |
20110255193 |
Kind Code |
A1 |
Hieda; Hiroyuki |
October 20, 2011 |
Magnetic recording medium and method of manufacturing the same
Abstract
According to one embodiment, a magnetic recording medium
includes a data region and a servo region adjacent to the data
region and including a magnetic recording layer, the magnetic
recording layer including first and second patterned regions
adjacent to each other, the first patterned region including a
first nonmagnetic matrix and first magnetic particles dispersed in
the first nonmagnetic matrix and having magnetization oriented in a
first direction, the second patterned region includes a second
nonmagnetic matrix and second magnetic particles dispersed in the
second nonmagnetic matrix and having magnetization oriented in a
second direction opposite to the first direction, sizes of the
first magnetic particles being smaller than sizes of the second
magnetic particles.
Inventors: |
Hieda; Hiroyuki;
(Yokohama-shi, JP) |
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
44788023 |
Appl. No.: |
13/064463 |
Filed: |
March 25, 2011 |
Current U.S.
Class: |
360/135 ; 216/22;
428/840; 428/840.5; G9B/5.293 |
Current CPC
Class: |
G11B 5/855 20130101;
B82Y 10/00 20130101; G11B 5/82 20130101; G11B 5/66 20130101; G11B
5/70 20130101; G11B 5/59655 20130101; G11B 5/743 20130101 |
Class at
Publication: |
360/135 ;
428/840; 428/840.5; 216/22; G9B/5.293 |
International
Class: |
G11B 5/82 20060101
G11B005/82; G11B 5/84 20060101 G11B005/84; G11B 5/62 20060101
G11B005/62 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2010 |
JP |
2010-093336 |
Claims
1. A magnetic recording medium, comprising: a data region; and a
servo region adjacent to the data region and including a magnetic
recording layer, wherein the magnetic recording layer comprises
first and second patterned regions adjacent to each other, the
first patterned region comprises a first nonmagnetic matrix and
first magnetic particles dispersed in the first nonmagnetic matrix
and has magnetization oriented in a first direction, the second
patterned region comprises a second nonmagnetic matrix and second
magnetic particles dispersed in the second nonmagnetic matrix and
has magnetization oriented in a second direction opposite to the
first direction, and sizes of the first magnetic particles are
smaller than sizes of the second magnetic particles.
2. The magnetic recording medium according to claim 1, wherein
either of the first and second patterned regions forms a pattern
corresponding to a servo signal.
3. The magnetic recording medium according to claim 1, wherein the
servo region further includes an underlayer on which the magnetic
recording layer is stacked, and protrusions are formed on the
underlayer at positions where the first magnetic particles are
formed, and the surface of the underlayer is flat at a position
corresponding to the second patterned region.
4. The magnetic recording medium according to claim 3, wherein the
underlayer is made of ruthenium (Ru) or Ru alloy.
5. A magnetic recording medium, comprising: an underlayer; an
interlayer formed on the underlayer, wherein the interlayer
comprises first and second regions adjacent to each other, the
first region has holes that pass from a surface of the underlayer
to a surface of the interlayer, and the second region has a flat
surface; first magnetic particles formed on the first region of the
underlayer, wherein the first magnetic particles comprise easy axes
of magnetization; a first nonmagnetic matrix formed on the first
region and surrounding the first magnetic particles; and a
non-oriented part formed on the second region, wherein the
non-oriented part comprises a nonmagnetic material and a magnetic
material, and the magnetic material has an easy axis of
magnetization different from easy axes of magnetization of the
first magnetic particles.
6. The magnetic recording medium according to claim 5, wherein the
magnetic material comprises dispersed magnetic particles in the
nonmagnetic material, and sizes of the first magnetic particles are
smaller than sizes of the dispersed magnetic particles.
7. The magnetic recording medium according to claim 5, wherein the
underlayer is made of ruthenium (Ru) or Ru alloy.
8. The magnetic recording medium according to claim 5, wherein the
interlayer is made of oxide(s), nitride(s) or organic
substance(s).
9. The magnetic recording medium according to claim 8, wherein the
interlayer is made of SiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5,
TiO.sub.2, Si.sub.3N.sub.4, AlN, TaN, photoresist, or
organosilicate.
10. A method of manufacturing a magnetic recording medium,
comprising: forming a resist layer on an underlayer; imprinting a
stamper having a concavo-convex pattern on the resist layer to
transfer the concavo-convex pattern onto a surface of the resist
layer; forming a region having protrusions and a region having a
flat surface to the underlayer by etching the underlayer with use
of the patterned resist layer as a mask; removing the resist layer
from the underlayer; and forming a magnetic recording layer on the
underlayer.
11. The method according to claim 10, wherein the underlayer is
made of ruthenium (Ru) or Ru alloy.
12. A method of manufacturing a magnetic recording medium,
comprising: forming an interlayer on an underlayer, the interlayer
including first and second regions adjacent to each other and made
of oxide(s), nitride(s) or organic substance(s); forming a resist
layer on the interlayer; imprinting a stamper having a
concavo-convex pattern on the resist layer to transfer the
concavo-convex pattern onto a surface of the resist layer; etching
the interlayer using the patterned resist layer as a mask to form
holes that pass from a top-surface of the interlayer to a
bottom-surface of the interlayer in the first region; removing the
resist layer from the interlayer to form the holes and to form a
flat surface on in the second region; and forming a magnetic
recording layer on the first region and the second region.
13. The method according to claim 12, wherein etching the
interlayer is performed such that the second region of the
interlayer remains on the underlayer.
14. The method according to claim 12, wherein etching the
interlayer is performed such that the second region of the
interlayer is removed.
15. The method according to claim 12, wherein the interlayer is
made of SiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5, TiO.sub.2,
Si.sub.3N.sub.4, AlN, TaN, photoresist, or organosilicate.
16. The method according to claim 12, wherein the underlayer is
made of ruthenium (Ru) or Ru alloy.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2010-093336, filed
Apr. 14, 2010; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to a magnetic
recording medium and a method of manufacturing the same.
BACKGROUND
[0003] JP-A 2004-295989 (KOKAI) discloses a magnetic recording
medium having a data region formed in such a manner that after a
magnetic material is segmented a nonmagnetic material is buried in
gaps. As disclosed in JP-A 2004-295989 (KOKAI), recesses of a data
region caused by microfabrication can be reduced to some extent by
burying the nonmagnetic material. However, a problem still remains
in that a recess is generated between a data region and servo
region. Since a deterioration of surface flatness of a magnetic
recording medium results in unstable flying of a magnetic recording
head and deteriorates a performance of the magnetic recording head
as the magnetic recording medium, it is expected to improve the
surface flatness.
[0004] JP-A 2009-193636 (KOKAI) discloses a magnetic recording
medium of a bit patterned medium (BPM) system having a magnetic
section and a nonmagnetic section in a servo region. In the
magnetic recording medium disclosed in JP-A 2009-193636 (KOKAI),
since the nonmagnetic section has no magnetism, a difference
between signals is small between the magnetic section and the
nonmagnetic section. As a result, it is difficult to accurately
read information on the servo region by a magnetic recording
head.
[0005] Further, it requires a lot of steps to manufacture the
magnetic recording mediums as described in JP-A 2004-295989 (KOKAI)
and 2009-193636 (KOKAI).
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic plan view of a magnetic recording
medium according to an embodiment;
[0007] FIGS. 2A and 2B are plan views along a circumferential
direction of the magnetic recording medium according to the
embodiment;
[0008] FIG. 3 is an enlarged plan view of a data region of the
magnetic recording medium according to the embodiment;
[0009] FIG. 4 is an enlarged plan view of an address section of the
magnetic recording medium according to the embodiment;
[0010] FIG. 5 is an enlarged plan view of a burst section of the
magnetic recording medium according to the embodiment;
[0011] FIG. 6 is a sectional view showing a servo region of a
magnetic recording medium according to a first embodiment;
[0012] FIG. 7 is a sectional view showing a servo region of a
magnetic recording medium according to a second embodiment;
[0013] FIG. 8 is a sectional view showing a servo region of a
magnetic recording medium according to a third embodiment;
[0014] FIGS. 9A and 9B are perspective views showing servo regions,
which are partly broken, of magnetic recording mediums according to
second and third embodiments, respectively; and
[0015] FIGS. 10A and 10B are sectional views showing an embodiment
of a magnetic recording medium while it is being manufactured.
DETAILED DESCRIPTION
[0016] In general, according to one embodiment, a magnetic
recording medium comprises a data region and a servo region
adjacent to the data region and including a magnetic recording
layer, the magnetic recording layer comprising first and second
patterned regions adjacent to each other, the first patterned
region comprising a first nonmagnetic matrix and first magnetic
particles dispersed in the first nonmagnetic matrix and having
magnetization oriented in a first direction, the second patterned
region comprises a second nonmagnetic matrix and second magnetic
particles dispersed in the second nonmagnetic matrix and having
magnetization oriented in a second direction opposite to the first
direction, sizes of the first magnetic particles being smaller than
sizes of the second magnetic particles.
[0017] Embodiments will be explained below referring to the
drawings.
[0018] FIG. 1 shows a schematic plan view of a magnetic recording
medium 1 according to an embodiment. FIG. 1 is a view of the
magnetic recording medium 1 when viewed from an upper surface. As
shown in FIG. 1, a servo region 2 and a data region 3 exist in the
magnetic recording medium 1. The data region 3 is a region in which
user data is recorded, and the servo region 2 is a region in which
a servo signal necessary to write and read the user data is
held.
[0019] On the magnetic recording medium 1, the servo region 2 is
formed in an arc shape corresponding to a locus which a head slider
accesses on the servo region 2. The length of the servo region 2 in
a circumferential direction is formed longer as a radius position
approaches an outer side of the servo region 2. Although 16 servo
regions 2 are shown in FIG. 1, 100 or more servo regions 2 are
formed in an actual medium.
[0020] FIGS. 2A and 2B show plan views of the magnetic recording
medium 1 according to the embodiment along a circumferential
direction.
[0021] FIGS. 2A and 2B are enlarged schematic views of a portion
which is across the servo region 2 and cut out from the overall
image of the magnetic recording medium 1 of FIG. 1. A right
direction on the sheet shows a circumferential direction of the
magnetic recording medium 1. An upper direction on the sheet shows
a radial direction of the magnetic recording medium 1.
[0022] FIG. 2A shows a magnetic recording medium (discrete track
medium, DTR) in which the data region 3 includes a granular
magnetic material 31 separated by a nonmagnetic material in a
radial direction. The granular magnetic material 31 (which is also
called a granular structure) comprises minute magnetic particles
having magnetism, which are dispersed in a base material of a
nonmagnetic material.
[0023] FIG. 2B shows a magnetic recording medium (bit patterned
medium, BPM) in which the data region 3 includes magnetic dots 32
segmented in a dot state. The magnetic recording medium 1 can
configure the data region 3 in any mode of DTR and BPM.
[0024] As shown in FIGS. 2A and 2B, the servo region 2 includes a
preamble section 21, an address section 22, and a burst section 23.
The preamble section 21, the address section 22 and the burst
section 23 of the servo region 2 are formed with patterns for
providing a servo signal.
[0025] The preamble section 21 is performed on PLL (Phase Locked
Loop) processing for synchronizing a servo signal read clock with
respect to the time lag caused by the rotational deviation of the
medium. The preamble section 21 is also performed on AGC (Auto Gain
Control) processing for properly maintaining a signal read
amplitude. In the preamble section 21, protruded recording regions
which continue without being segmented in the radius direction and
have a circular-arc shape are repeatedly formed in the
circumferential direction.
[0026] The address section 22 has a servo signal recognition code
called a servo mark, sector data, and cylinder data, which are
formed in Manchester code and the like at the same pitch as the
circumferential pitch of the preamble section 21. The cylinder data
vary from one servo track to another servo track. Thus, in order to
minimize the difference in the cylinder data between adjacent
tracks and thus minimize the influence of an address read error on
the seek operation, the cylinder data are recorded as data
converted into Gray code and then Mnachester coded.
[0027] In the burst section 23, an off-track detection region for
detecting the off-track amount from the cylinder address in the
on-track state is formed.
[0028] FIG. 3 shows an enlarged plan view of the data region 3. The
data region 3 shown in FIG. 3 is used in the magnetic recording
medium 1 having the configuration of a BPM. As shown in FIG. 3, the
data region 3 includes the magnetic dots 32 and a nonmagnetic
matrix 33. The magnetic dot 32 includes a magnetic material and
acts as a minimum recording unit of the user data. The nonmagnetic
matrix 33 includes a nonmagnetic material and has a role for
physically and magnetically separating the magnetic dots 32.
[0029] The nonmagnetic matrix 33 mainly includes a nonmagnetic
material and is defined as a structure that buries the space
between the magnetic structures (magnetic dots 32) to separate the
structures from each other. Likewise, a nonmagnetic matrix 28 in
the servo region to be described later mainly includes a
nonmagnetic material, and the nonmagnetic matrix 28 is a structure
that buries the space between the magnetic structures (first
magnetic particles 26 and second magnetic particles 27).
[0030] FIG. 4 shows an enlarged view of the address section 22 of
the magnetic recording medium 1. FIG. 5 shows an enlarged view of
the burst section 23.
[0031] As shown in FIG. 4, the address section 22 is formed by
ensembles of magnetic particles shown by reference numerals 26 and
27. In FIG. 4, small magnetic particles, which have a predetermined
size and are disposed uniformly, are called first magnetic
particles 26. In FIG. 4, magnetic particles, which have various
sizes, are disposed at random, and are larger than the first
magnetic particles 26, are called second magnetic particles 27.
Further, the structure, which buries the peripheries of the first
magnetic particles 26 and the second magnetic particles 27, is
called the nonmagnetic matrix 28. Further, a region, which is
surrounded by a broken line in FIG. 4, and in which the first
magnetic particles 26 are collected, is called a first region 24.
Further, a region, which is surrounded by a dotted line in FIG. 4
and in which the second magnetic particles 27 are collected, is
called a second region 25.
[0032] Patterns are formed to the address section 22 by disposing
the first region 24 and the second region 25 on specific
positions.
[0033] The structure, to which slant lines are attached in the
address section 22 of FIG. 2A or 2B and which is drawn in a
rectangle, corresponds to the first region 24 shown in FIG. 4. The
structure, which is drawn as a blank in the address section 22 of
FIGS. 2A and 2B, corresponds to the second region 25.
[0034] Like the address section 22, the burst section 23 shown in
FIG. 5 is also formed by ensembles of the first magnetic particles
26 and the second magnetic particles 27, and the peripheries of
these magnetic particles are buried by the nonmagnetic matrix 28.
Further, the first region 24 in which the first magnetic particles
26 are collected and the second region 25 in which the second
magnetic particles 27 are collected are present. The structure, to
which slant lines are attached and which is drawn in a square in
the burst section 23 of FIG. 2A or 2B, corresponds to the first
region 24 shown in FIG. 5. Further, the structure, which is drawn
in blank in the burst section 23 of FIG. 2A or 2B, corresponds to
the second region 25 shown in FIG. 5.
[0035] Like the address section 22 and the burst section 23, the
preamble section 21 is also formed by collecting the first magnetic
particles 26, the second magnetic particles 27, and the nonmagnetic
matrix 28, and the patterns of the preamble section 21 are formed
by the dispositions of the first region 24 and the second region
25.
[0036] The size (sectional area viewed from an upper surface) of
the first magnetic particles 26, which exists in the first region
24 of the servo region 2, is as large as or smaller than the
magnetic dots 32 of the data region 3 shown in FIG. 3 (magnetic
recording medium according to BPM).
[0037] Further, when the data region 3 of the magnetic recording
medium 1 has the structure of a DTR, the data region 3 includes a
track in which a magnetic material is segmented by a nonmagnetic
material in the radial direction as shown in FIG. 2A.
[0038] The first magnetic particles 26 and the second magnetic
particles 27 can be magnetized. However, since the size of the
first magnetic particles 26 is different from the size of the
second magnetic particles, the first magnetic particles and the
second magnetic particles have a different coercive force. In
general, it is known that even if magnetic particles are formed of
the same material, magnetic particles having a smaller size are
less influenced by a diamagnetic field, with a result that the
magnetic particles having the smaller size have a larger coercive
force. The size of the first magnetic particles 26 is smaller than
the size of the second magnetic particles. Thus, the coercive force
Hc1 of the first magnetic particles 26 becomes higher than the
coercive force Hc2 of the second magnetic particles 27. The
magnetic recording medium 1 magnetizes the first magnetic particles
26 and the second magnetic particles 27 in an opposite direction,
respectively making use of the difference between the coercive
forces. That is, after a magnetic recording layer including the
first magnetic particles 26 and the second magnetic particles 27 is
formed, the magnetic recording layer is first magnetized by a
magnetic force higher than Hc1 so that the first magnetic particles
26 and the second magnetic particles 27 are magnetized in the same
direction. Thereafter, the second magnetic particles 27 are
magnetized in an opposite direction by a magnetic force lower than
Hc1 and higher than Hc2 so that only the magnetization of the
second magnetic particles 27 is inverted. At the time, since the
magnetization of the second magnetic particles 27 is stabilized by
the diamagnetic field generated from the first magnetic particles
26, the occurrence of reverse magnetization in the second magnetic
particles 27 can be prevented. With the operation, the first region
24 and the second region 25 in the servo region 2 form not only
patterns depending on a difference between the sizes of magnetic
particles that constitutes the first region 24 and the second
region 25 but also magnetic patterns. The magnetic pattern
functions as the servo patterns of the magnetic recording medium
1.
[0039] Since the magnetic recording medium 1 has the feature, the
magnetic recording medium 1 stabilizes the signal held by the servo
region 2.
[0040] In a conventional magnetic recording medium of a DTR system
or a BPM system, a servo region is formed of a magnetic material
section and a nonmagnetic material section.
[0041] In contrast, in the magnetic recording medium 1, the servo
region 2 is formed of a magnetic material magnetized in a specific
direction (first direction) and a magnetic material magnetized in a
direction opposite to the direction (second direction). Therefore,
a difference between signals in a pattern is made more definite in
the servo region 2 of the magnetic recording medium 1 than in a
conventional DTR or BPM servo region, thereby servo information can
be read accurately by a recording head. Magnetization directions
(first and second directions) are notably parallel with the film
thickness direction of the magnetic recording layer 7 (vertical to
a film surface). This is because the parallel directions are
suitable to increase a recording density of the magnetic recording
medium.
[0042] Next, the structure of the magnetic recording medium 1
according to the first embodiment will be explained using a
sectional view.
[0043] FIG. 6 shows a sectional view of the servo region 2 of the
magnetic recording medium 1 according to the first embodiment. In
the magnetic recording medium 1 according to the first embodiment,
a soft magnetic underlayer (not shown), an underlayer 4, a magnetic
recording layer 7, and a protective film (not shown) are laminated
on a substrate (not shown) in this order. The underlayer 4 is a
layer to control the easy axis of magnetization of the magnetic
particles of the magnetic recording layer 7 formed on the
underlayer 4 and to orient the directions of the easy axis of
magnetization in a direction vertical to the film surface. Further,
a lubrication agent such as perfluoropolyether is appropriately
applied on the protective film. FIG. 6 shows only the underlayer 4
and the magnetic recording layer 7.
[0044] The magnetic recording layer 7 has the first region 24 and
the second region 25. In the first region 24, the first magnetic
particles 26 are separated by the nonmagnetic matrix 28 in a
direction vertical to the laminate direction of the magnetic
recording layer 7. In the second region 25, the second magnetic
particles 27 are separated by the nonmagnetic matrix 28 in a
direction vertical to the laminate direction of the magnetic
recording layer 7.
[0045] In the first region 24, the surface of the underlayer 4
includes a plurality of protrusions. In the second region 25, the
surface of the underlayer 4 is flat. The first magnetic particles
26 exist on the protrusions of the underlayer 4. Further, in the
second region 25, the second magnetic particles 27 exist on the
surface of the underlayer 4.
[0046] The data region 3 is also formed of the magnetic recording
layer 7 on the underlayer 4 like the servo region 2, and a
plurality of protrusions is formed on the surface of the underlayer
4. Also in the data region 3, the magnetic dots 32 are formed on
the protrusions of the underlayer 4 like the first region 24. When
the magnetic recording medium 1 is of the DTR system, protrusions
exist on the surface of the underlayer 4 of the section in which
the magnetic particles exist in the granular magnetic material 31
which configures the data region 3. In contrast, the surface of the
underlayer 4 of the section in which the nonmagnetic material
exists is flat.
[0047] The structure including the first magnetic particles 26 and
the second magnetic particles 27 as shown in FIG. 6 can be formed
by employing a concavo-convex structure on the surface of the
underlayer 4. In the magnetic recording medium 1, protrusions are
formed on a part of the surface of the underlayer 4, and the first
magnetic particles 26 are formed on the protrusions. In contrast,
the other part of the surface of the underlayer 4 is made flat, and
the second magnetic particles 27 are formed on the flat
surface.
[0048] Although the height of the protrusions formed on the surface
of the underlayer 4 can be appropriately selected depending on the
condition of forming the magnetic recording layer 7, the height is
notably 1 nm or more. In contrast, in the region in which the
surface of the underlayer 4 is flat, the arithmetic average
roughness (Ra) of the surface is notably less than 0.5 nm. When the
magnetic recording layer 7 is formed on the underlayer 4 having
such a surface shape, the first magnetic particles 26 and the
second magnetic particles 27 are formed in a different mode in the
region having the protrusions of the underlayer 4 and in the region
which is flat, respectively.
[0049] In the region having the protrusions of the underlayer 4
(which corresponds to the first region 24), the magnetic material
included in the magnetic recording layer 7 is epitaxially grown
selectively on the respective protrusions, and the fine first
magnetic particles 26 are formed. In contrast, the nonmagnetic
material included in the magnetic recording layer 7 is selectively
grown between the protrusions of the underlayer 4 and becomes the
nonmagnetic matrix 28.
[0050] In the region in which the surface of the underlayer 4 is
flat (which corresponds to the second region 25), since a
protrusion which acts as a start point of growth does not exist,
the magnetic material included in the magnetic recording layer 7 is
grown from sparse positions, and thus the second magnetic particles
27 which are larger than the first magnetic particles 26 are
formed. At the time, the nonmagnetic material included in the
magnetic recording layer 7 is formed to surround the second
magnetic particles 27 and becomes the nonmagnetic matrix 28.
[0051] In the magnetic recording medium 1 according to the
embodiment, the underlayer 4 is previously processed and the
magnetic material and the nonmagnetic material are selectively
formed on the underlayer 4. Accordingly, since it is not necessary
to perform etching to the magnetic material in a manufacturing
process, the surface of the magnetic recording layer 7 is unlikely
to be made rough. Accordingly, since the magnetic recording layer 7
having a high flatness can be provided, data can be written and
read by a magnetic read/write head accurately.
[0052] Since the underlayer 4 is previously processed, the magnetic
recording medium 1 can be manufactured by a small number of
steps.
[0053] FIG. 7 shows a sectional view of a servo region 2 of a
magnetic recording medium 1 according to a second embodiment. FIG.
9A shows a perspective view of the servo region 2 which is partly
broken. In FIG. 9A, the structure of a magnetic recording layer 7
is shown transparently using broken lines. The sectional view of
the servo region 2 of the magnetic recording medium 1 shown in FIG.
7 corresponds to a sectional view taken along an A-A' line in FIG.
9A.
[0054] In the magnetic recording medium 1 according to the
embodiment, an interlayer 5, which includes any material of oxides,
nitrides, or organic substances, exists between an underlayer 4 and
the magnetic recording layer 7. As shown in FIG. 7, in a first
region 24, the interlayer 5 is formed with a plurality of holes
which pass from the surface of the interlayer 5 to the surface of
the underlayer 4, and the underlayer 4 is exposed on the bottom
section of the interlayer 5. First magnetic particles 26 are buried
in the holes. The holes correspond to the section of the interlayer
5 in which first magnetic particles 26 shown in FIG. 9A are
formed.
[0055] In a second region 25, the interlayer 5 is made to a flat
layer. A non-oriented part 6 is formed on the interlayer 5. Since
no non-oriented part 6 is formed on the underlayer 4, easy axes of
magnetization of the thus formed magnetic particles on section 6
face an arbitrary direction to a film surface. Note that the easy
axes of magnetization of the magnetic particles on section 6
preferably face an in-plane direction of a film surface and do not
face a vertical direction of the film surface. Since the surface of
the interlayer 5 is flat, a magnetic material which configures the
non-oriented part 6 is formed on the interlayer 5 in a shape larger
than the first magnetic particles 26, and a nonmagnetic material
surrounds the periphery of the magnetic material. Since the
magnetic material has the large size, the coercive force of the
magnetic material is also lower than the first magnetic particles
26.
[0056] In the embodiment, the servo patterns of the servo region 2
are formed by the first region 24 and the second region 25.
[0057] Although FIG. 9A shows four of the holes and four of the
first magnetic particles 26 formed in the holes at intervals,
actually, more holes and more first magnetic particles 26 can be
formed more densely.
[0058] The structure of the magnetic recording layer 7 shown in
FIG. 7 can be formed by processing the interlayer 5. When the
magnetic recording layer 7 is formed to the interlayer 5 having the
region (first region 24) which includes the holes and the flat
region (second region 25) as shown in FIG. 7 and FIG. 9A, the
magnetic recording layer 7 is formed in a different mode in the
respective regions.
[0059] In the regions having the holes, a magnetic material
included in the magnetic recording layer 7 is epitaxially grown
selectively from the surface of the underlayer 4 where the holes
are formed so that the first magnetic particles 26 are formed. In
contrast, the nonmagnetic material included in the magnetic
recording layer 7 is selectively grown on the interlayer 5 so that
a nonmagnetic matrix 28 is formed so as to surround the first
magnetic particles 26.
[0060] In contrast, in the flat region (the second region 25),
since a start point from which a magnetic material grows does not
exist on the surface of the interlayer 5, a magnetic material which
configures the non-oriented part 6 is oriented on the interlayer 5
in a shape larger than the first magnetic particles 26, and a
nonmagnetic material is formed surrounding the periphery of the
magnetic material.
[0061] In a data region 3 of the embodiment, the interlayer 5 and
the magnetic recording layer 7 are sequentially formed on the
underlayer 4 like the servo region 2. Also, in the data region 3, a
plurality of holes are formed passing from the surface of the
interlayer 5 up to the surface of the underlayer 4 like the first
region 24. Magnetic dots 32 are formed to the holes. A nonmagnetic
material is formed on the interlayer 5 where the holes are not
formed. The nonmagnetic material is formed to surround the magnetic
dots 32.
[0062] FIG. 8 shows a sectional view of a servo region 2 of a
magnetic recording medium 1 according to a third embodiment.
Further, FIG. 9B shows a perspective view of the servo region 2
which is partly broken. In FIG. 9B, the structure of a magnetic
recording layer 7 is shown transparently using broken lines. The
sectional view of the servo region 2 of the magnetic recording
medium 1 shown in FIG. 8 corresponds to the sectional view taken
along a line B-B' in FIG. 9B.
[0063] In the magnetic recording medium 1 according to the
embodiment, an interlayer 5 including any material of oxides,
nitrides, or organic substances exists between an underlayer 4 and
the magnetic recording layer 7 in a first region 24. In contrast,
in a second region 25, no interlayer 5 exists on the underlayer
4.
[0064] As shown in FIG. 8, a plurality of holes, which pass from
the surface of the interlayer 5 up to the surface of the underlayer
4, are formed to the interlayer 5, and the underlayer 4 is exposed
on the bottom section of the interlayer 5. First magnetic particles
26 are buried in the holes. The holes correspond to the section of
the interlayer 5 to which the first magnetic particles 26 shown in
FIG. 9B are formed. A nonmagnetic matrix 28 is formed to surround
the first magnetic particles 26.
[0065] In contrast, second magnetic particles 27, each of which has
a sparse size and a sparse disposition, and the nonmagnetic matrix
28, which buries the peripheries of the second magnetic particles
27, exist in the region (second region 25) of the underlayer 4 in
which no interlayer 5 is formed. The servo patterns of the servo
region 2 are formed of the first region 24, in which magnetic
particles whose magnetization faces a direction by being applied
with a magnetic field as described above are collected, and a
second region 25 in which magnetic particles whose magnetization
faces a direction opposite to the above direction are
collected.
[0066] Although FIG. 9B shows four of the holes and four of the
first magnetic particles 26 formed in the holes at intervals,
actually, more holes and more first magnetic particles 26 can be
formed more densely.
[0067] The structure of the magnetic recording layer 7 shown in
FIG. 8 can be formed by processing the interlayer 5. When the
magnetic recording layer 7 is formed to the region (first region
24) having the holes and to the region of the underlayer (second
region 25) to which no interlayer 5 is formed as shown in FIGS. 8
and 9B, the magnetic recording layer 7 is formed in a different
mode in the respective regions.
[0068] In the regions having the holes, a magnetic material
included in the magnetic recording layer 7 is epitaxially grown
selectively from the surface of the underlayer 4 where the holes
are formed so that the first magnetic particles 26 are formed. In
contrast, the nonmagnetic material included in the magnetic
recording layer 7 is selectively grown on the interlayer 5 so as to
surround the first magnetic particles 26 so that a nonmagnetic
matrix 28 is formed.
[0069] In contrast, in the region of the underlayer 4 in which the
interlayer 5 is not formed, since no protrusion acting as a start
point of growth exists, a magnetic material included in the
magnetic recording layer 7 is grown from sparse positions, and thus
the second magnetic particles 27 larger than the first magnetic
particles 26 are formed. At the time, the nonmagnetic material
included in the magnetic recording layer 7 is formed to surround
the second magnetic particles 27 and becomes the nonmagnetic matrix
28.
[0070] Also in the embodiment, like the second embodiment, the data
region 3 has the interlayer 5 and the magnetic recording layer 7
sequentially formed on the underlayer 4 like in the servo region 2.
Also in the data region 3, a plurality of holes are formed passing
from the surface of the interlayer 5 up to the surface of the
underlayer 4 like the first region 24. The holes are formed with
magnetic dots 32. A nonmagnetic material is formed on the
interlayer 5 on which no hole is formed. The nonmagnetic material
is formed to surround the magnetic dots 32.
[0071] In addition to the modes of processing of the surface of the
underlayer 4 in the first to third embodiments, the surface of the
underlayer 4 can be processed as shown in, for example, FIGS. 10A
and 10B. FIGS. 10A and 10B are sectional views showing a state just
before the magnetic recording layer 7 is formed.
[0072] In FIG. 10A, after the interlayer 5 is formed on the
underlayer 4, a second underlayer 10, which includes the same
material as the underlayer 4, is further formed on the underlayer
4.
[0073] In FIG. 10B, after the second underlayer 10 is formed like
FIG. 10A, the surface of the second underlayer 10 is further
flattened by etching and the like, and a part of the interlayer 5
is exposed from the surface of the second underlayer 10.
[0074] In FIG. 10A, the second underlayer 10 has a protrusion on
the surface thereof in a pattern corresponding to the pattern of
the interlayer 5 existing under the second underlayer 10. Note that
holes are formed in the interlayer 5.
[0075] In the mode shown in FIG. 10A, the surface of the second
underlayer 10 is not processed different from the underlayer 4 and
the interlayer 5. Accordingly, the surface of the second underlayer
10 has a high flatness, and further, the magnetic recording layer 7
having a high flatness can be formed on the second underlayer
10.
[0076] In the mode shown in FIG. 10B, the protrusion at the
interlayer 5 has a height lower than that in the third embodiment
shown in FIG. 8. Therefore, when the magnetic recording layer 7 is
formed on the second underlayer 10, the height of the protrusion on
the surface of the magnetic recording layer 7 can be reduced.
[0077] Next, a method of manufacturing a magnetic recording medium
1 will be explained. First, a method of manufacturing the magnetic
recording medium 1 shown in FIG. 6 will be explained.
[0078] First, the underlayer 4 is formed on the substrate.
Thereafter, a resist layer is formed on the underlayer 4. Patterns
are transferred to the resist layer with a stamper on which the
patterns are previously formed by a nanoimprint method. At the
time, since a protruding and recessed shape and a flat shape are
formed on the stamper, a shape corresponding to the first region 24
and a shape corresponding to the second region 25 are transferred
to the resist layer as the patterns. The patterns are formed on the
underlayer 4 by etching the underlayer 4 using the resist layer as
a mask.
[0079] Next, the magnetic recording layer 7 is formed on the
underlayer 4 on which the patterns are formed. The magnetic
recording layer 7 is formed by performing sputtering using a
mixture of a magnetic material and a nonmagnetic material as a
target. The underlayer 4 is formed with a region whose surface
includes a protruding and recessed shape and a flat region.
Accordingly, patterns are formed by the first magnetic particles
26, the second magnetic particles 27 and the nonmagnetic matrix 28,
depending on the patterns of the surface.
[0080] The magnetic recording medium 1 according to the first
embodiment shown in FIG. 6 can be formed by the manufacturing
method.
[0081] An example of a more specific manufacturing method will be
shown below.
[0082] First, a soft magnetic underlayer is formed on the substrate
by sputtering. The soft magnetic underlayer preferably has a film
thickness of about several tens of nanometers to about several
hundreds of micron meters.
[0083] Next, the underlayer 4 is formed on the soft magnetic
underlayer by sputtering. The underlayer 4 preferably has a
thickness of several tens of nanometers to about several hundreds
of nanometers. Increasing the distance between the magnetic
recording layer 7 to be formed later and the soft magnetic
underlayer deteriorates write characteristics. Therefore, the
underlayer 4 preferably has a thickness of 50 nm or less in
particular.
[0084] Next, a resist layer is formed on the underlayer 4.
[0085] Patterns are transferred to the thus formed resist layer by
a nanoimprint method. The patterns of a stamper used in the
nanoimprint method can be formed by an electron beam drawing.
Highly dense patterns of 10 nm or less can be formed using
calixarene and HSQ as an electron beam resist. The thickness of the
resist layer is set in consideration of the depth of recesses to be
formed and the etching selectivity between a resist layer material
and an underlayer material at an etching step which is performed
subsequently. A thermal nanoimprint, a room temperature
nanoimprint, a UV nanoimprint, and the like can be used as the
nanoimprint method.
[0086] Next, the patterns of the resist layer are transferred to
the underlayer 4 by dry etching. Thereafter, an etching mask is
stripped off. Note that the etching may be continued until the
etching mask is removed by adjusting the thickness of the etching
mask. With the operation, a stripping step of the etching mask can
be omitted.
[0087] Note that a material for etching the underlayer 4 may be
configured as a multilayer structure. For example, after a carbon
film and a Si film are sequentially formed on the underlayer 4, the
resist layer may be formed on the films. In the case, the Si film
is dry etched using a resist layer on which the patterns are
nanoimprinted as a mask. Thereafter, the carbon film is further dry
etched using the Si film as a mask so that an etching mask to the
underlayer 4 can be formed. In the case, a concavo-convex pattern
having a high aspect rate can be formed to the carbon film using
dry etching performed by an oxygen gas when the carbon film is
etched. Therefore, since the etching mask remains for a long time
when the underlayer 4 is etched, protrusions having a high aspect
rate can be formed.
[0088] As a modification of the processing method of the underlayer
4, it is also possible to configure the underlayer 4 as a laminated
structure. That is, first, after a concavo-convex pattern is formed
to the underlayer 4 by the above method, the second underlayer 10
can be formed thereon. In this case, since the underlayer 4 the
surface of which is damaged by the etching process is covered with
the second underlayer 10, a surface having a high flatness can be
obtained.
[0089] As described above, a fine concavo-convex pattern according
to the data region 3 and the servo region 2 can be formed on the
surface of the underlayer 4. Note that since no concavo-convex
pattern is formed on the surface of the underlayer 4 corresponding
to the second region 25 of the servo region 2, the roughness of the
surface is approximately the same as the roughness of the surface
after the surface is formed by sputtering.
[0090] Next, the magnetic recording layer 7 is formed by sputtering
a magnetic material and a nonmagnetic material. At the time, the
magnetic material is epitaxially grown from the protruding sections
of the underlayer 4. In contrast, the nonmagnetic material is
selectively grown in the recesses of the underlayer 4.
[0091] As described above, a granular structure corresponding to
the patterns formed by the nanoimprint is formed to the magnetic
recording layer 7.
[0092] In contrast, in the flat region of the underlayer 4
corresponding to the second region 25, since no seed structure
exists, a granular structure having large crystal particles is
formed.
[0093] Next, a method of manufacturing the magnetic recording
medium 1 shown in FIG. 7 will be explained.
[0094] Since a step of forming the underlayer 4 on the substrate is
the same as the step of forming the underlayer 4 of the magnetic
recording medium 1 shown in FIG. 6, an explanation of the step is
omitted.
[0095] The interlayer 5 including any of oxides, nitrides, or
organic substances is formed on the underlayer 4. A resist layer is
formed on the interlayer 5, and patterns are transferred to the
resist layer by nanoimprinting a stamper. At the time, the patterns
formed on the resist layer include a plurality of holes and a flat
region. The holes correspond to the first region 24, and the flat
region corresponds to the second region 25.
[0096] The interlayer 5 is etched using the patterned resist layer
as a mask, and the patterns are transferred to the interlayer 5.
Thereafter, the magnetic recording layer 7 is formed on the
interlayer 5 on which the patterns are formed. By the operation,
the patterns are formed by the first magnetic particles 26, the
nonmagnetic matrix 28, and the like according to the patterns of
the interlayer 5. The magnetic recording medium 1 according to the
second embodiment shown in FIG. 7 is formed by the method.
[0097] An example of a more specific manufacturing method will be
shown below.
[0098] The soft magnetic underlayer can be formed like the first
embodiment. The underlayer 4 is formed on the thus formed soft
magnetic underlayer. Further, the interlayer 5 is formed by forming
any of oxides, nitrides, and organic substances on the underlayer
4. When the oxides or the nitrides are used, the interlayer 5 can
be formed by RF sputtering. When the organic substances are used,
the interlayer 5 can be formed by spin-coating a solution in which
the organic substances are dissolved in a solvent. Further, when
the interlayer 5 is a carbon film and the like, the interlayer 5
can be formed by sputtering.
[0099] Next, a resist layer is formed on the interlayer 5.
[0100] Next, a stamper is nanoimprinted to the resist layer and
patterns corresponding to the data region 3 and the servo region 2
are formed. The interlayer 5 is processed by dry etching using the
resist layer as a mask. Thereafter, the remaining resist layer is
stripped off when necessary. In the region corresponding to the
first region 24, a plurality of holes are formed to the interlayer
5 passing through up to the underlayer 4 by processing the
interlayer 5. In contrast, in the region corresponding to the
second region 25 of the interlayer 5, the interlayer 5 remains in a
flat state without being subjected to any processing (FIG. 7). The
magnetic recording layer 7 is formed on the interlayer 5 to which
the patterns are formed as described above.
[0101] Note that, as a modification of the step for forming the
underlayer 4 and the interlayer 5, an underlayer may be further
laminated on the underlayer 4 and the interlayer 5. That is, after
protruding and recessed patterns are formed to the interlayer 5, a
second underlayer 10 can be laminated thereon (FIG. 10A). In this
case, since the underlayer 4 and the interlayer 5 whose surfaces
are damaged by an etching process are covered with the second
underlayer 10, surfaces having a high flatness can be obtained.
[0102] A magnetic material and a nonmagnetic material are formed on
the second underlayer 10 to which the patterns are formed by
sputtering, thereby forming the magnetic recording layer 7. With
the operation, in the region corresponding to the first region 24,
the magnetic material is epitaxially grown selectively in the
section in which the second underlayer 10 is formed on the
interlayer 5. At the time, in the second underlayer 10 in which no
interlayer 5 is formed, the nonmagnetic material is selectively
grown and surrounds the magnetic material.
[0103] In contrast, in the region corresponding to the second
region 25, since no interlayer 5 is formed, the surface of the
second underlayer 10 is flat. Accordingly, since no protrusion
acting as a start point of growth exists, the magnetic material is
grown from sparse positions, and thus a granular structure having
large crystal particles is formed.
[0104] Next, a method of manufacturing the magnetic recording
medium 1 shown in FIG. 8 will be explained.
[0105] Since a step of forming the underlayer 4 on the substrate is
the same as the step of forming the underlayer 4 of the magnetic
recording medium 1 shown in FIG. 6, an explanation of the step is
omitted.
[0106] The magnetic recording medium 1 shown in FIG. 8 is different
from the magnetic recording medium 1 shown in FIG. 7 in that no
interlayer 5 is formed on the underlayer 4 in the second region
25.
[0107] The difference is caused by a difference of shape of an
etching mask when the interlayer 5 is processed. That is, the shape
of the etching mask protrudes in the region corresponding to the
first region 24 after a nanoimprint is performed, and the height of
the protrusions of the etching mask becomes higher than the height
of the etching mask in the region corresponding to the second
region 25. When etching is performed to such the etching mask, in
the second region 25 in which the etching mask is low, since the
interlayer 5 can be removed by the etching, the underlayer 4 is
exposed. In the thus processed interlayer 5, a plurality of holes
are formed to the interlayer 5 passing through up to the underlayer
4 in the region corresponding to the first region 24. A magnetic
material is epitaxially grown selectively in the holes from which
the underlayer 4 is exposed. At the time, in the section in which
no hole is formed to the interlayer 5, a nonmagnetic material is
epitaxially grown selectively so as to surround the magnetic
material.
[0108] In contrast, in the region corresponding to the second
region 25, as shown in FIG. 8, a magnetic material having larger
particle size is epitaxially grown at random, and a nonmagnetic
material is epitaxially grown around the magnetic material.
[0109] Note that, as a modification of processing of the underlayer
4 and the interlayer 5 in the third embodiment, the second
underlayer 10 may be processed after the second underlayer 10 is
further laminated on the underlayer 4 and the interlayer 5. That
is, after patterns are formed to the interlayer 5, the second
underlayer 10 is laminated thereon, and further the surface of the
second underlayer 10 is flattened by etching and the like (FIG.
10B). At the time, a part of the interlayer 5 is exposed from the
surface of the second underlayer 10. In this case, the height of
the interlayer 5 from the surface of the second underlayer 10 can
be made small. Therefore, when the magnetic recording layer 7 is
laminated on the interlayer 5, the protrusions on the surface of
the magnetic recording layer 7 can be made small.
[0110] Next, materials for manufacturing the magnetic recording
medium 1 will be explained.
[0111] Nonmagnetic metal substrates such as a glass substrate, a
plastic substrate, a ceramics substrate, and an aluminum, a Si
substrate, and the like can be used as the substrate.
[0112] CoZrNb, CoTaZr, FeCoB, FeCoN, FeTaC, FeTaN, FeNi, FeSi,
NiFeNb, Co, CoB, or FeAlSi, and the like, which have a high
saturation magnetic flux density and good soft magnetic
characteristics, are used as the soft magnetic underlayer. The soft
magnetic underlayer may be a single layer or may be a laminated
layer. When the soft magnetic underlayer is the laminated layer, an
arbitrary nonmagnetic intermediate layer can be inserted between
the respective soft magnetic layers.
[0113] The underlayer 4 may be a single layer structure or may be a
laminated layer structure, and when CoPt alloy is used as the
magnetic recording layer 7, a continuous film of Ru or Ru alloy is
preferably used as the underlayer 4. After a metal film other than
Ru is formed on the soft magnetic underlayer as the underlayer 4,
the continuous film of Ru or Ru alloy may be formed as the second
underlayer 10. Further, both the underlayer 4 and the second
underlayer 10 may be formed as the continuous film of Ru or Ru
alloy in two steps.
[0114] The magnetic recording layer 7 may be configured as a
vertical magnetic recording layer. A mixture of a magnetic material
and a nonmagnetic material may be used to form the magnetic
recording layer 7. Co alloys such as CoPt, CoCr, CoCrPt, and CoCrTa
can be used as the magnetic material. Oxides such as SiO.sub.2,
Al.sub.2O.sub.3, Ta.sub.2O.sub.5, and TiO.sub.2 or nitrides such as
Si.sub.3N.sub.4, AlN, and TaN can be used as the nonmagnetic
material.
[0115] A material, which has a high affinity with the nonmagnetic
material included in the magnetic recording layer 7, is preferable
as the material of the interlayer 5. For example, oxides such as
SiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5, and TiO.sub.2,
nitrides such as Si.sub.3N.sub.4, AlN, and TaN or organic
substances such as a photoresist, and organosilicate can be
used.
EXAMPLES
Example 1
[0116] A magnetic recording medium 1 was manufactured. A magnetic
recording layer 7 was formed on a processed underlayer 4.
[0117] A 120-nm-thick soft magnetic underlayer of CoZrNb was formed
by DC sputtering on a 2.5-inch glass substrate for HDD at a degree
of vacuum of 1.times.10.sup.-5 Pa in a 0.7-Pa Ar gas at a power of
500 W. The underlayer 4 was formed by forming Ru to a 20 nm
thickness on the soft magnetic underlayer at a power of 500 W. SOG
(spin on glass) was applied on the underlayer 4 to a film thickness
of 10 nm as a resist layer. Next, a stamper having patterns was
imprinted to the resist layer at a press pressure of 30 tons. The
patterns of the stamper used a structure which was configured such
that dots were disposed at the positions corresponding to first
magnetic particles 26 of a servo region 2 in a triangle grid state
at 14-nm pitches. Next, the Ru was etched by 5 nm by performing
argon ion milling under conditions of an acceleration voltage of
400V and an ion current of 40 mA. After the etching under such
conditions, no SOG remained on the surface of the Ru.
[0118] A 15-nm-thick vertical magnetic recording layer whose
magnetization faced a laminate direction was formed on the etched
underlayer 4 as the magnetic recording layer 7 using a CoCrPt-8 mol
% SiO.sub.2 composite target. Next, after a 7-nm thick carbon
protective film was formed, a 1.5-nm-thick perfluoroether
lubrication film was formed by a dip method, and the magnetic
recording medium 1 was obtained.
[0119] After a 15-kOe magnetic field was applied to the obtained
magnetic recording medium 1 and magnetized, an 8-kOe inverted
magnetic field was applied thereto. When a reproduction output of
the servo region 2 of the medium was measured using a spin stand, a
good signal could be obtained.
Comparative Example 1
[0120] A magnetic recording medium 1 was manufactured similarly to
the embodiment 1 except that a stamper had different patterns. The
stamper used in the comparative example had no dot structure at the
positions corresponding to first magnetic particles 26 of a servo
region 2 and had a structure in which a first region 24 was concave
in its entirety in place of the dot structure. With the
configuration, the patterns of an underlayer 4, in which the first
region 24 was convex in its entirety to a second region 25, could
be obtained.
[0121] After a 15-kOe magnetic field was applied to the magnetic
recording medium 1 formed using the underlayer 4 and magnetized, an
8-kOe magnetic field was applied thereto. When a reproduction
output of the servo region 2 of the medium was measured using a
spin stand, a clear signal could not be obtained. It is conceived
that the result shows that since the particle size of granules of
the servo region 2 was formed uniformly, no difference appeared
between coercive forces.
Example 2
[0122] A magnetic recording medium 1 was manufactured. After an
interlayer 5 was formed and processed, a magnetic recording layer 7
was formed thereon.
[0123] The same steps as in the embodiment 1 were performed until
an underlayer 4 was formed using Ru. Thereafter, a 10-nm-thick
SiO.sub.2 film was formed on the underlayer 4 by RF sputtering. SOG
was applied on the SiO.sub.2 film to a film thickness of 10 nm as a
resist layer.
[0124] A stamper was imprinted to the resist layer. The same
patterns as the example 1 were used as the patterns of the stamper.
Next, the SiO.sub.2 film was etched 12 nm by argon ion milling
using the resist layer as a mask.
[0125] After the interlayer 5 including SiO.sub.2 was processed, a
15-nm-vertical magnetic recording layer was formed as the magnetic
recording layer 7 using a CoCrPt-8 mol % SiO.sub.2 composite
target. Next, after a 7-nm thick carbon protective film was formed,
a 1.5-nm-thick perfluoroether lubrication film was formed by a dip
method, and the magnetic recording medium 1 was obtained.
[0126] After a 15-kOe magnetic field was applied to the obtained
magnetic recording medium 1 and magnetized, an 8-kOe inverted
magnetic field was applied thereto.
[0127] When a reproduction output of the servo region 2 of the
medium was measured using a spin stand, a good signal could be
obtained.
Example 3
[0128] A magnetic recording medium 1 was manufactured.
[0129] After an underlayer 4 was processed, an underlayer 4 was
further laminated thereon, and a magnetic recording layer 7 was
further formed.
[0130] The underlayer 4 was formed similarly to the embodiment 1
and processed making use of a nanoimprint method. A 5-nm-thick Ru
film was formed on the underlayer 4 as a second underlayer 10. A
15-nm-thick vertical magnetic recording layer was formed on the
second underlayer 10 as the magnetic recording layer 7 using a
CoCrPt-8 mol % SiO.sub.2 composite target.
[0131] When the thus obtained magnetic recording medium 1 was
measured by X-ray diffraction, the half-value width of the peak
rocking curve of CoCrPt (002) of the magnetic recording medium 1 of
the example 3 was improved to 3.5.degree. although that of the
magnetic recording medium 1 of the embodiment 1 was
5.0.degree..
[0132] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
* * * * *