U.S. patent application number 11/857174 was filed with the patent office on 2008-01-17 for process of producing master carrier for magnetic transfer.
This patent application is currently assigned to FUJI PHOTO FILM CO., LTD. (now FUJIFILM Corporation). Invention is credited to Seiji Kasahara, Masakazu Nishikawa.
Application Number | 20080014456 11/857174 |
Document ID | / |
Family ID | 34101136 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080014456 |
Kind Code |
A1 |
Nishikawa; Masakazu ; et
al. |
January 17, 2008 |
PROCESS OF PRODUCING MASTER CARRIER FOR MAGNETIC TRANSFER
Abstract
A process for producing a master carrier contains steps of:
forming a desired pattern on a support to form a resist pattern
support; forming a first ferromagnetic thin film on the resist
pattern support by a vacuum film forming method; forming a third
ferromagnetic thick film on the first ferromagnetic thin film by an
electroplating; and peeling the support from the resist pattern
support provided with the first ferromagnetic thin film and the
third ferromagnetic thick film.
Inventors: |
Nishikawa; Masakazu;
(Kanagawa, JP) ; Kasahara; Seiji; (Kanagawa,
JP) |
Correspondence
Address: |
SUGHRUE-265550
2100 PENNSYLVANIA AVE. NW
WASHINGTON
DC
20037-3213
US
|
Assignee: |
FUJI PHOTO FILM CO., LTD. (now
FUJIFILM Corporation)
Kanagawa
JP
|
Family ID: |
34101136 |
Appl. No.: |
11/857174 |
Filed: |
September 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10916527 |
Aug 12, 2004 |
7294251 |
|
|
11857174 |
Sep 18, 2007 |
|
|
|
Current U.S.
Class: |
428/544 ;
G9B/5.309 |
Current CPC
Class: |
G11B 2005/001 20130101;
G11B 5/865 20130101; G11B 5/82 20130101; G11B 5/012 20130101; G11B
5/59688 20130101; Y10T 428/12 20150115 |
Class at
Publication: |
428/544 |
International
Class: |
G11B 5/86 20060101
G11B005/86 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2003 |
JP |
2003-295327 |
Claims
1. A master carrier, which is produced by process comprising:
forming a support having a projection pattern in accordance with a
desired information on a surface of said support; forming a first
ferromagnetic thin film on said support having said projection
pattern by a vacuum film forming method; forming a third
ferromagnetic thick film on said first ferromagnetic thin film by
an electroplating; and peeling said support from said support
provided with said first ferromagnetic thin film and said third
ferromagnetic thick film.
2. The master carrier according to claim 1, wherein said third
ferromagnetic thick film comprises a nickel.
3. The master carrier according to claim 1, said process further
comprising: forming a second ferromagnetic thin film between said
first ferromagnetic thin film and said third ferromagnetic thick
film by said vacuum film forming method, said second ferromagnetic
thin film having a same element as said third ferromagnetic thick
film.
4. The master carrier according to claim 3, wherein said second
ferromagnetic thin film has a film thickness of 10 nm to 100
nm.
5. The master carrier according to claim 1, wherein said first
ferromagnetic thin film has a first saturation magnetization, and
said third ferromagnetic thick film has a third saturation
magnetization; and a ratio of said first saturation magnetization
to said third saturation magnetization is 1 or more.
6. A magnetic transfer medium in which servo information is
recorded by a magnetic transfer method using a master carrier that
is produced by a process comprising: forming a support having a
projection pattern in accordance with a desired information on a
surface of said support; forming a first ferromagnetic thin film on
said support having said projection pattern by a vacuum film
forming method; forming a third ferromagnetic thick film on said
first ferromagnetic thin film by an electroplating; and peeling
said support from said support provided with said first
ferromagnetic thin film and said third ferromagnetic thick film.
Description
[0001] This is a divisional of application Ser. No. 10/916,527
filed Aug. 12, 2004, which claims benefit of priority under 35
U.S.C. .sctn. 119 from Japanese Patent Application No. 2003-295327,
filed on Aug. 19, 2003. The entire disclosure of each of the prior
applications is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a process of producing a
master carrier for magnetic transfer having a projection pattern
for bringing it into intimate contact with a slave medium to
magnetically transfer a desired magnetic pattern onto the slave
medium, especially a master carrier for magnetic transfer in which
a deficiency is hardly generated in a magnetic layer thereof.
[0004] 2. Description of the Prior Art
[0005] In magnetic recording media, media capable of undergoing
so-called high-speed access, which have a mass storage volume so as
to record a large quantity of information following an increase of
the information amount, are inexpensive, and preferably, are able
to read out a necessary portion within a short period of time, are
desired. As one example thereof, high-density magnetic disk media
to be used in hard disk units or flexible disks (hereinafter
referred to as "FD") are known. For the sake of realizing the mass
storage volume, a so-called tracking servo technology in which a
magnetic head accurately scans a narrow track width and reproduces
a signal at a high S/N ratio bears a large role.
[0006] During one round of the disk, a servo signal for tracking,
an address information signal, a reproduction clock signal, and the
like are recorded at certain spacings as a so-called preformat. The
magnetic head is set up in such a manner that it reads out such a
signal of preformat and corrects its own position, whereby it can
accurately run on the track.
[0007] At present, the foregoing preformat is prepared by writing
the signals in every disk and in every track using a dedicated
servo recording unit. The servo recording unit is provided with a
magnetic head having, for example, a head width of about 75% of the
track pitch. First, a disk is rotated in the state that the
magnetic head is made closed to the disk, and signals of each track
are written while moving the magnetic head every a half track
pitch.
[0008] Since the foregoing servo recording unit is expensive and
takes a lot of time for preparing a preformat, this step occupies
the majority of the production costs. Thus, it is demanded to
realize a low cost.
[0009] Then, a method of realizing this by magnetic transfer in
place of writing of a preformat in every track is proposed (for
example, see U.S. Pat. No. 6,347,016).
[0010] In this magnetic transfer, a master carrier having a
projection pattern corresponding to information that is to be
transferred onto a slave medium as a medium to be magnetically
transferred, such as a magnetic disk medium, is prepared, and a
transfer magnetic field is applied in the sate that the master
carrier and the slave medium come into intimate contact with each
other, thereby transferring a magnetic pattern corresponding to
information (for example, servo signals) carried by the projection
pattern of the master carrier onto the slave medium. According to
this system, recording can be statically performed without changing
the relative position between the master carrier and the slave
medium, accurate preformat recording can be achieved, and the time
required for recording is extremely short.
[0011] For the sake of enhancing the transfer quality in the
foregoing magnetic transfer, how the master carrier is durable to
the order of several thousands sheets in the good intimate contact
state without causing breakage is important. That is, if the
intimate contact fails, regions where the magnetic transfer does
not take place are generated. If no magnetic transfer takes place,
signal failure is generated in the magnetic information to be
transferred onto the slave medium, leading to a lowering of the
signal quality. In the case where the recorded signal is a servo
signal, a sufficient tracking function is not obtained, resulting
in a lowering of reliability.
[0012] FIG. 5 shows the production steps of a master carrier for
magnetic transfer according to the related art.
[0013] According to this, a nickel (Ni) conductive layer is formed
on a silicon support G1' having formed thereon a pattern of a
resist (R1) with projections, and a third ferromagnetic thick film
F3 made of nickel as the major component is then formed by
electroplating (see FIG. 5-(6)); and this is peeled from the resist
pattern support G1' to separate a resist R1 contact part of the
third ferromagnetic thick film F3 side from a part (b) of the
resist pattern support G1 (see FIG. 5-(7)).
[0014] After the separation, when the resist R1 of a part (a) of
the third ferromagnetic thick film F3 side and dusts are cleaned up
and removed by means of O.sub.2 ashing, etc., a nickel original
plate F3 is obtained (see FIG. 5-(8)). A magnetic layer film F1 is
laminated thereon by the sputtering method, whereby a master
carrier M for magnetic transfer is obtained (see FIG. 5-(9)).
[0015] As the resist pattern support G1', nickel, silicon, quartz
plate, glass, aluminum, ceramics, synthetic resins, and the like
are used. As magnetic materials of the magnetic layer film F1, Co,
Co alloys (for example, CoNi, CoNiZr, and CoNbTaZr), Fe, Fe alloys
(for example, FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, and FeTaN), Ni,
and Ni alloys (for example, NiFe) are used.
[0016] As materials of the metal support F3, Ni or Ni alloys, etc.
can be used. As the plating for preparing this support, a variety
of metallic film formation methods including electroless plating,
electroplating, sputtering, and ion plating were applied.
[0017] In the foregoing related art methods, the Ni conductive
layer was provided on the resist support G1' by film formation and
subjected to electroplating to prepare the patterned Ni support F3;
and the magnetic layer F1 was formed thereon by the sputtering
method to form the master carrier M for magnetic transfer. When a
number of sheets of slave media were subjected to magnetic transfer
using the thus obtained master carrier M for magnetic transfer,
transfer failure and breakage of the slave media occurred in the
order of several thousands sheets.
[0018] Since it was thought that this is caused due to breakage of
the master, the master was analyzed. As a result, it was
ascertained that the magnetic layer formed on the patterned Ni
support failed.
[0019] As a result of further investigations, it was noted from
factorial separation experiments performed while taking the film
thickness of the magnetic layer, etc. as a parameter that an
internal stress in the magnetic layer was larger than the adhesive
strength between the support and the magnetic layer, whereby
peeling of the magnetic layer occurred therein.
[0020] It was noted that this phenomenon is liable to take place in
the case of fine patterns of not more than 100 nm.
[0021] For the purpose of enhancing the adhesive strength, it was
attempted to reduce the internal stress by changing the conditions
of the Ni support surface treatment and the magnetic layer film
formation. As a result, though a certain effect could be confirmed,
a large enhancement was not achieved yet. In the light of the
above, it was concluded that an improvement in the pattern coating
property is necessary while ensuring an adhesive strength of a
certain level or more between the magnetic layer and the Ni
support.
[0022] In the foregoing related art methods, for example, if a soft
magnetic layer made of FeCo is formed on the projection pattern
formed by the Ni electroplating by the vacuum film forming method
(for example, the spattering method), duration of FeCo piling (in
the spattering process), it is rare that FeCo is piling on the
projection while keeping the width of the projection, but FeCo is
piling while also widening in the width direction. Therefore, in
the projection pattern being finer than 100 nm, the piled FeCo
films contact one another between adjacent projections, resulting
in disordering of the pattern shape.
SUMMARY OF THE INVENTION
[0023] Accordingly, it is an object of the present invention to
provide a process of producing a master carrier for magnetic
transfer. That is, by previously forming a ferromagnetic thin film
(F1) that has hitherto been prepared in the final step on a resist
support and performing electroplating using this ferromagnetic thin
film as a conductive layer, an electrodynamic alloying step can be
realized, thereby achieving a large enhancement of the adhesive
strength, and in addition thereto, by forming the ferromagnetic
thin film (F1) on the resist pattern, the pattern coating property
can be improved by the formation of the ferromagnetic thin film
(F1).
[0024] Specifically, a first aspect of the invention is concerned
with a process of producing a master carrier for magnetic transfer,
the process comprising: forming a support having a projection
pattern in accordance with a desired information on a surface of
the support; forming a first ferromagnetic thin film (F1) on the
support having the projection pattern by the vacuum film forming
method; forming a third ferromagnetic thick film (F3) on the first
ferromagnetic thin film (F1) by electroplating; and peeling the
support from the support provided with the first ferromagnetic thin
film and the third ferromagnetic thick film.
[0025] It must be noted that the term "a projection pattern"
comprises a projection and a depression, however the term
"depression" as used herein indicates a portion between one
projection and another projection. In addition, The above mentioned
"a support having a projection pattern in accordance with a desired
information on a surface" includes such supports, in which (i) the
projection pattern is formed on a flat support (for example, a
glass plate, a silicone wafer or the like) by use of a photo resist
(the projection is composed of the photo resist), (ii) in the above
(i), the photo resist in the projection is subjected, as an etching
resist, to a further etching treatment, and the resistless support
is treated on the surface with the etching, (iii) in the above
(ii), the photo resist composing the projection is removed, and the
projection are formed on the surface itself of the support, and
(iv) the metal plate or the like is the plate of the above (i) or
(ii) having, on the surface, the projection made of the metal (for
example, Ni) by the electroforming.
[0026] It is preferred that the third ferromagnetic thick film (F3)
is made of nickel (Ni) as the major component.
[0027] It is more preferably that a second ferromagnetic thin film
(F2) constituted of an element the same as in the third
ferromagnetic thick film (F3) is formed between the first
ferromagnetic thin film (F1) and the third ferromagnetic thick film
(F3) by the vacuum film forming method.
[0028] It is much more preferably that the second ferromagnetic
thin film (F2) has a film thickness (dF2) in the range of from 10
nm to 100 nm.
[0029] It is most preferably that a saturation magnetization (MsF1)
of the first ferromagnetic thin film (F1) and a saturation
magnetization (MsF3) of the third ferromagnetic thick film (F3) are
in the relation of (MsF1/MsF3)>1.
[0030] A second aspect of the invention is concerned with a
magnetic transfer medium having servo information recorded therein
by the magnetic transfer method using a master carrier for magnetic
transfer produced by the production process as set forth in the
first aspect.
[0031] A third aspect of the invention is concerned with a process
of producing a preformatted magnetic recording medium, which
comprises the steps of: preparing a master carrier,
[0032] preparing a slave medium comprising a non-magnetic support
having a magnetic recording layer thereon,
[0033] initially magnetizing the magnetic recording layer of said
slave medium to a predetermined direction,
[0034] bringing a surface of the master carrier into intimate
contact with the magnetic recording layer of the slave medium at a
predetermined pressure to form a conjoined body, and
[0035] applying a transfer magnetic field to the conjoined body in
a direction opposite to the predetermined direction, thereby
obtaining the magnetic recording medium having the recorded data,
wherein the master carrier is produced by the process as set forth
in the first aspect.
[0036] In the light of the above, by previously forming the
ferromagnetic thin film (F1) and performing electroplating using
this ferromagnetic thin film as a conductive layer, an
electrodynamic alloying step can be realized, thereby achieving a
large enhancement of the adhesive strength, and in addition
thereto, by forming the ferromagnetic thin film (F1) on the resist
pattern, the pattern coating property can be improved by the
formation of the ferromagnetic thin film (F1).
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a slant view to show a slave medium 2 and mater
carries 3, 4.
[0038] FIG. 2 is a view to explain the basic steps of this magnetic
transfer, in which FIG. 2A shows a step of applying a magnetic
field in one direction to subject the slave medium to initial
direct-current magnetization; FIG. 2B shows a step of bringing the
master carrier and the slave medium into intimate contact with each
other and applying a magnetic field in the opposite direction; and
FIG. 2C shows the state after the magnetic transfer.
[0039] FIG. 3 shows a process of producing a master carrier for
magnetic transfer according to a first embodiment of the
invention.
[0040] FIG. 4 shows a process of producing a master carrier for
magnetic transfer according to a second embodiment of the
invention.
[0041] FIG. 5 shows a process of producing a master carrier for
magnetic transfer according to the related art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] A best mode for carrying out the invention will be described
below in detail with reference to the accompanying drawings.
[0043] First of all, basic steps of magnetic transfer for
transferring information onto a slave medium using a master carrier
will be described with reference to FIGS. 1 and 2.
[0044] FIG. 1 is a slant view to show a slave medium 2 and master
carriers 3, 4.
[0045] For example, the slave medium 2 is a flexible disk in which
a hub 2b is fixed in the center of a disk-like recording medium 2a,
and the recording medium 2a has recording surfaces 2d, 2e having a
magnetic body layer formed thereon on the both surfaces of a
disk-like base 2c made of a non-magnetic body such as a flexible
polyester sheet.
[0046] Also, the master carriers 3, 4 are each formed of a rigid
body on a ring-like disk, on one surface of which is provided a
transferred information-carrying surface having formed thereon a
fine projection pattern to come into intimate contact with the
recording surfaces 2d, 2e of the slave medium 2, respectively. In
the master carriers 3, 4, a projection pattern is formed for the
lower-side recording surface 2d and the upper-side recording
surface 2e of the slave medium 2, respectively. When the master
carrier 3 is exemplified, the projection pattern is formed within a
doughnut-shaped region surrounded by dotted lines in the drawing.
Incidentally, the master carriers 3, 4 as shown in FIG. 1 are
constructed of supports 31, 41 having a projection pattern formed
thereon and soft magnetic layers 32, 42 formed on the projection
pattern, respectively. By providing the magnetic layers having good
transfer characteristics in this way, it is possible to undergo
good magnetic transfer.
[0047] In the case where the support is a non-magnetic body, it is
necessary to provide a magnetic layer.
[0048] Also, in the case where a support made of a ferromagnetic
metal is used, and a magnetic layer is coated on its projection
pattern surface, for the sake of avoiding the magnetic influence of
the support, it is preferred to provide a non-magnetic layer
between the support and the magnetic layer. Further, by coating a
protective film such as diamond-like carbon (DLC) in the uppermost
layer, contact durability is enhanced by this protective film so
that it becomes possible to undergo magnetic transfer of a number
of times. Moreover, an Si film may be formed beneath the DLC
protective film by means of sputtering, etc.
[0049] FIG. 2 is a view to explain the basic steps of this magnetic
transfer, in which FIG. 2A shows a step of applying a magnetic
field in one direction to subject the slave medium to initial
direct-current magnetization; FIG. 2B shows a step of bringing the
master carrier and the slave medium into intimate contact with each
other and applying a magnetic field in the opposite direction; and
FIG. 2C shows the state after the magnetic transfer. Incidentally,
in FIG. 2, with respect to the slave medium 2, only its lower
recording surface 2d is shown.
[0050] As shown in FIG. 2A, an initial magnetic field Hin is
previously applied to the slave medium 2 in one direction of the
track direction, thereby undergoing initial magnetization
(direct-current demagnetization). Thereafter, as shown in FIG. 2B,
the recording surface 2d of this slave medium 2 is brought into
intimate contact with an information-carrying surface coated with
the magnetic layer 32 on a fine projection pattern of the support
31 of the master carrier 3, and a transfer magnetic field Hdu is
applied in the opposite direction to the foregoing initial magnetic
field in the track direction of the slave medium 2, thereby
undergoing magnetic transfer. As a result, as shown in FIG. 2C,
information (for example, a servo signal) corresponding to the
projection pattern of the master carrier 3 is magnetically
transferred and recorded on the magnetic recording surface (track)
of the master carrier 3. Here, while the lower-side recording
surface 2d of the slave medium 2 and the lower-side master carrier
3 have been explained, the upper-side recording surface 2e of the
slave medium 2 is brought into intimate contact with the upper-side
master carrier 4, thereby undergoing magnetic transfer in the same
manner as shown in FIG. 1. The magnetic transfer onto the upper and
lower recording surfaces 2d, 2e of the slave medium 2 may be
carried out at the same time or successively for every surface.
[0051] Also, even in the case where the projection pattern of the
master carrier 3 is a negative pattern having a projection shape
reverse to the positive pattern shown in FIG. 2, by reversing the
direction of the initial magnetic field Hin and the direction of
the transfer magnetic field Hdu, it is possible to magnetically
transfer and record the same information. Incidentally, with
respect to the initial magnetic field and the transfer magnetic
field, it is necessary to employ values defined while taking into
account a holding power of the slave medium and relative magnetic
permeability of each of the master carriers and the slave
medium.
[0052] FIG. 3 shows a process of producing a master carrier for
magnetic transfer according to a first embodiment of the invention.
The process of producing a master carrier for magnetic transfer
will be described below based on this drawing.
[0053] First of all, the surface of a silicon disk (or a glass
disk) G1 is polished smoothly (see FIG. 3-(1)); and after coating a
resist contact liquid thereon, a positive working resist liquid is
coated by spin coating, etc. and then baked to form a resist R1
(see FIG. 3-(2)).
[0054] Laser beams (or electron beams) L1, L2, . . . , L6 modulated
corresponding to a servo signal (or its mirror symmetric signal)
are irradiated in a specified site of this resist R1, thereby
exposing and drawing a prescribed tracking pattern on the resist R1
on the whole surface of the disk G1 (see FIG. 3-(3)).
(Incidentally, for the purpose of making the specified site of the
resist R1 easy to see, hatching is omitted only in FIG. 3-3, but
the hatching should be originally given likewise other drawings.)
After baking again, the resist R1 is developed to remove exposed
areas, thereby forming a projection shape by the resist R1 (see
FIG. 3-(4)).
[0055] The disk G1 is etched from the projection shape side of the
resist R1. In this way, convex parts protected by the resist R1
remain, whereas concave parts not protected by the resist R1 (for
example, an arrow part A) are eroded into the silicon disk G1 (see
FIG. 3-(5)).
[0056] On the resulting resist pattern support G1' having
projections formed thereon, a first ferromagnetic thin film F1 is
first formed by the vacuum film forming method such as sputtering
and vapor deposition (see FIG. 3-(6)). This step is a
characteristic feature of the invention. As the first ferromagnetic
thin film F1, an FeCo alloy having good absorption of the magnetic
field is adequate.
[0057] Further, a third ferromagnetic thick film F3 is formed on
this first ferromagnetic thin film F1 by means of electroplating
(see FIG. 3-(7)). The third ferromagnetic thick film F3 is
preferably made of nickel (Ni) as the major component.
Incidentally, the height of the projections is in the order of 100
nm, and the thickness of the third magnetic thick film F3 is in the
order of 300 .mu.m.
[0058] As the resist pattern support G1', nickel, silicon, quartz
plate, glass, aluminum, ceramics, synthetic resins, and the like
are used.
[0059] As magnetic materials of the magnetic layer film F1, Co, Co
alloys (for example, CoNi, CoNiZr, and CoNbTaZr), Fe, Fe alloys
(for example, FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, and FeTaN), Ni,
and Ni alloys (for example, NiFe) are used.
[0060] As materials of the metal support F3, Ni or Ni alloys, etc.
can be used.
[0061] This is then peeled from the resist pattern support G1' so
as to separate a part (a) of the third ferromagnetic thick film F3
side from a part (b) of the resist pattern support G1 (see FIG.
3-(8)).
[0062] When peeling off, for preventing physical destructions of
the support, an easily peeling layer may be provided between the
support G1' (R1) and the ferromagnetic thin film F1. The easily
peeling layer is desirably composed with chemically inactive
substances. In particular, a carbon based easily peeling layer
(DLC, or spattering C) is desirable.
[0063] The easily peeling layer has a thickness of from 2 to 10 nm,
preferably about 3 to 7 nm. Being less than 2 nm, the easily
peeling layer does not accomplish the functions. Being more than 10
nm, the pattern coating property of the ferromagnetic thin film F1
is lowered. After peeling, the easily peeling layer may be used as
a protecting layer.
[0064] After the separation, by removing the resist R1 of the part
(a) of the first ferromagnetic thin film F1 side by means of
O.sub.2 ashing, etc., a master carrier M for magnetic transfer,
which is a reversed plate, is prepared. When the resulting master
carrier M for magnetic transfer is seen, it is noted that a master
carrier for magnetic transfer in which the first ferromagnetic thin
film F1 is formed in the right-angled state without causing
rounding of the pattern shape (shoulder collapse) (see an arrow
site B) is obtained in the projection parts of the third
ferromagnetic thick film F3 (see FIG. 3-(9)).
[0065] FIG. 4 shows a process of producing a master carrier for
magnetic transfer according to a second embodiment of the
invention. The process of producing a master carrier for magnetic
transfer will be described below based on this drawing.
[0066] In the production process according to the second
embodiment, since the steps (1) to (6) for preparing a resist
pattern support G1' having projections formed thereon are the same
as in FIG. 3, the explanation will be omitted.
[0067] After forming a first ferromagnetic thin film F1 made of an
FeCo alloy on a resist pattern support G1' having projections
formed thereon by the sputtering method, the vapor deposition
method, etc. (see FIG. 4-(6)), according to the second embodiment,
a second ferromagnetic thin film F2 constructed of an element the
same as in a third ferromagnetic thick film F3 is formed on this
first ferromagnetic thin film F1 by the sputtering method (see FIG.
4-(6')). The second ferromagnetic thin film F2 preferably has a
thickness (dF2) in the range of from 10 nm to 100 nm. Thereafter, a
third ferromagnetic thick film F3 made of nickel (Ni) as the major
component is formed on the second ferromagnetic thin film F2 by
means of electroplating (see FIG. 4-(7)); and this is then peeled
from the resist pattern support G1', thereby separating it into a
part (a) of the third ferromagnetic thick film F3 side and a part
(b) of the resist pattern support G1 (see FIG. 4-(8)). After the
separation, by removing a resist R1 of the part (a) of the third
ferromagnetic thick film F3 side by O.sub.2 ashing, etc., a master
carrier M for magnetic transfer, which is a reversed plate, is
prepared.
[0068] In the light of the above, according to the second
embodiment of the invention, the second ferromagnetic thin film F2
constructed of an element the same as in the third ferromagnetic
thick film F3 is formed between the first ferromagnetic thin film
(FeCo) F1 and the third ferromagnetic thick film F3 by the
sputtering method. This is because if foreign matters (for example,
FeCo) are incorporated into a plating bath, there is some
possibility of occurrence of deposition of impurities upon
reduction, and therefore, any possibility is eliminated in advance
by providing the thin layer of Ni on FeCo.
[0069] When the resulting plate is seen, it is noted that a master
carrier for magnetic transfer in which the first ferromagnetic thin
film F1 is formed in the right-angled state without causing
rounding of the pattern shape (shoulder collapse) (see an arrow
site A) is obtained in the projection parts of the third
ferromagnetic thick film F3 (see FIG. 4-(9)).
[0070] Also, it is preferable that the relation between a
saturation magnetization (MSF1) of the first ferromagnetic thin
film (F1) and a saturation magnetization (MsF3) of the third
ferromagnetic thick film (F3) are in the relation represented by
the following expression (1). (MsF1/MsF3)>1 (1)
[0071] The reason for this is as follows. That is, in the case
where signal recording is performed by means of magnetic transfer,
it is necessary that the pattern part of the master carrier
efficiently absorbs and releases many magnetic fluxes. For
achieving this, it is necessary that the master magnetic layer in
the vicinity of the slave, which contributes most likely to the
signal recording, is unsaturated at the time of magnetic transfer
and has a high saturation magnetization.
[0072] Accordingly, by meeting the relation represented by the
foregoing expression (1), even when the third ferromagnetic thick
film (F3) is saturated, the first ferromagnetic thin film (F1) is
still not saturated and has high convergent and releasing
characteristics of magnetic fluxes. Thus, it is possible to realize
magnetic transfer with a good signal quality.
[0073] The invention will be described below with reference to the
following Examples.
EXAMPLES
[0074] A chemical sensitization type resist was coated in a
thickness of 100 nm on an 8-inch Si wafer, and a resist pattern of
radiant lines having a pitch length of 0.15 .mu.m, a track width of
1.0 .mu.m, a track pitch of 1.1 .mu.m, and a groove depth of 0.1
.mu.m was formed in a radius region to the position of from 20 mm
to 40 mm in the radius direction from the rotation center using
electron beams.
[0075] Thereafter, a soft magnetic layer made of 25 atomic % of
FeCo was prepared in a thickness of 100 nm on this resist pattern
at a support temperature of 25.degree. C.
[0076] An Ar sputtering pressure was set up at 0.15 Pa (1.08
mTorr). An input electric power was set up at 2.80 W/cm.sup.2.
[0077] After forming 25 atomic % of FeCo in a thickness of 100 nm,
Ni electroplating was performed in a thickness of an (Ni) support
of 0.3 mm. After electroplating, isolation from the resist support
and cleaning were carried out to prepare a master carrier, which
was then provided for use.
[0078] A glass plate was heated at 200.degree. C. under a condition
adjusted in a vacuum film formation unit (S-50S sputtering unit,
manufactured by Shibaura Mechatronics Corporation) by reducing the
pressure to 1.33.times.10.sup.5 Pa (1.0.times.10.sup.-7 Torr) at
room temperature and then introducing argon to set up the pressure
at 0.4 Pa (3.0 mTorr), to prepare a 3.5-inch type disk-like
magnetic recording medium containing 30 nm of CrTi and 30 nm of
CoCrPt and having an Ms of 5.7 T (4,500 gauss) and a cohesive force
Hc of 199 kA/m (25,000 e), which was then used as an inplane slave
medium.
1) Evaluation Method of Master Durability:
[0079] Using the same master carrier, the contact pressure between
the master carrier and the slave medium was set up at
7.4.times.10.sup.-3 Pa (7.5 kgf/cm.sup.2), and contact and peeling
were repeated 10,000 times. Thereafter, the master surface was
observed at random with respect to 500 visual fields at a
magnification of 480 times using a differential interference
microscope. In the 500 visual fields, the master durability was
evaluated according to the following criteria.
[0080] (a) Good (O): The number of portions where a deposit or
crack is formed is less than three.
[0081] (b) Bad (X): The number of portions where a deposit or crack
is formed is three or more.
2) Electromagnetic Transformation Characteristics:
[0082] 2-1) All of the slave media were placed in an
electromagnetic transformation characteristic analyzer (SS-60,
manufactured by Kyodo Denshi System Co., Ltd.) (heads: GMR heads
having a reproducing head gap of 0.12 .mu.m, a reproducing track
width of 0.45 .mu.m, a recording head gap of 0.18 .mu.m, and a
recording track width of 0.51 .mu.m), and the line speed at a
radius of 40 mm was set up at 10 m/sec. A read signal was subjected
to frequency division by a spectroanalyzer, and a difference (C/N)
of a peak intensity (C) of a primary signal to an externally
pressed medium nozzle (N) was measured.
[0083] A relative C/N was evaluated according to the following
criteria based on the C/N value of the head recording signal.
[0084] (a) Good (O): The relative C/N value is less than -3.0
dB.
[0085] (b) Moderate (.DELTA.) The relative C/N value is from -3.0
to -4.0 dB.
[0086] (c) Bad (X): The relative C/N value is -4.0 dB or more.
[0087] 2-2) In addition, a ratio (Wdup/Whead) of a transfer
recording carrier peak line (Wdup) to a head recording product
(Whead) was evaluated according to the following criteria.
[0088] (a) Stable (O): The Wdup/Whead ratio is not more than 1.
[0089] (b) Instable (X): The Wdup/Whead ratio exceeds 1.
[0090] In Example 1, an F1 layer having a thickness of 100 nm was
formed of FeCo (Co: 25%) before electroplating.
[0091] In Examples 2 to 5, magnetic transfer was carried out in the
same manner as in Example 1, except for changing the material
quality and thickness of F1 as shown in Table 1. That is, an F1
layer having a thickness of 200 nm was formed of FeCo (Co: 25%) in
Example 2; an F1 layer having a thickness of 100 nm was formed of
FeCo (Co: 30%) in Example 3; an F1 layer having a thickness of 500
nm was formed of FeCo (Co: 30%) in Example 4; and an F1 layer
having a thickness of 500 nm was formed of Ni in Example 5,
respectively.
Example 6
[0092] Except using as the plate a support formed with the pattern
(depth: 100 nm) on the resist pattern support itself from the RIE
method, the master carrier for magnetic transfer is the same as
that of Example 1.
Example 7
[0093] Except using the Ni support made by the plating to the root
of the resist pattern support, the master carrier for magnetic
transfer is the same as that of Example 1.
Example 8
[0094] Except forming the DLC film of 1 nm between the pattern
support/F1, the master carrier for magnetic transfer is the same as
that of Example 6.
Example 9
[0095] Except forming DLC film of 5 nm between the pattern
support/F1, the master carrier for magnetic transfer is the same as
that of Example 6.
Example 10
[0096] Except forming DLC film of 13 nm between the pattern
support/F1, the master carrier for magnetic transfer is the same as
that of Example 6. In Comparative Example 1, magnetic transfer was
carried out in the same manner as in Example 1, except that a
magnetic layer was formed on a patterned support after completion
of Ni electroplating.
[0097] In Comparative Example 2, magnetic transfer was carried out
in the same manner as in Example 2, except that a magnetic layer
was formed on a patterned support after completion of Ni
electroplating.
[0098] In Comparative Example 3, magnetic transfer was carried out
in the same manner as in Example 4, except that a magnetic Layer
was formed on a patterned support after completion of Ni
electroplating.
[0099] The results obtained are shown in Table 1. TABLE-US-00001
TABLE 1 Electromagnetic transformation Easily Adhesion
characteristics Order of Formation of peeling MsF1/ Master Relative
Line F1 formation F1 layer layer (nm) MsF3 durabilityt Judgment C/N
(dB) Judgment width Stability Example 1 Before FeCo 25 atomic Non
2.50 0 .largecircle. 0 .largecircle. 0.9 .largecircle.
electroplating % - 100 nm Example 2 Before FeCo 25 atomic Non 2.50
1 .largecircle. -0.1 .largecircle. 0.8 .largecircle. electroplating
% - 200 nm Example 3 Before FeCo 30 atomic Non 3.10 0 .largecircle.
0.1 .largecircle. 0.9 .largecircle. electroplating % - 100 nm
Example 4 Before FeCo 30 atomic Non 2.80 1 .largecircle. -0.2
.largecircle. 1 .largecircle. electroplating % - 500 nm Example 5
Before Ni - 200 nm Non 1.00 1 .largecircle. -3.4 .DELTA. 0.9
.largecircle. electroplating Example 6 Before FeCo 25 atomic Non
2.50 1 .largecircle. -0.8 .largecircle. 0.95 .largecircle.
electroplating % - 100 nm Example 7 Before FeCo 25 atomic Non 2.50
2 .largecircle. -0.6 .largecircle. 0. 98 .largecircle.
electroplating % - 100 nm Example 8 Before FeCo 25 atomic DCL-1 nm
2.50 1 .largecircle. -0. 9 .largecircle. 0. 96 .largecircle.
electroplating % - 100 nm Example 9 Before FeCo 25 atomic DCL-5 nm
2.50 0 .largecircle. -1.1 .largecircle. 0. 97 .largecircle.
electroplating % - 100 nm Example 10 Before FeCo 25 atomic DCL-13
nm 2.50 0 .largecircle. -2.3 .largecircle. 0.99 X electroplating %
- 100 nm Comparative After FeCo 25 atomic Non 2.60 3 X -0.5
.largecircle. 1. 1 X Example 1 electroplating % - 100 nm
Comparative After FeCo 25 atomic Non 2.60 4 X -1 .largecircle. 1.2
X Example 2 % - 200 nm Comparative electrop FeCo 25 atomic Non 2.70
10 X -5.2 X 1. 9 X Example 3 % - 500 nm
[0100] In Table 1, Examples 1 to 4, and 6 to 10 exhibit "0" in both
the adhesion and the electromagnetic transformation characteristics
(relative C/N and Wdup/Whead); and Example 5 exhibits "0", except
that the relative C/N of the electromagnetic transformation
characteristics is ".DELTA.".
[0101] In contrast, Comparative Examples 1 to 3 exhibited "X" in
both the adhesion and Wdup/Whead.
[0102] From these results, it could be confirmed that the method of
the invention in which a first ferromagnetic thin film (F1) is
first formed on a resist pattern support by the sputtering method,
and a third ferromagnetic thick film (F3) is then formed on this
first ferromagnetic thin film (F1) by means of electroplating is an
extremely effective method.
[0103] In contrast, it could be proven that the related art method
in which an Ni conductive layer is subjected to film formation on a
resist support, electroplating is performed to form a patterned Ni
support, and a magnetic layer is then formed thereon by the
supporting method is inferior.
[0104] The present invention is not limited to the specific
above-described embodiments. It is contemplated that numerous
modifications may be made to the present invention without
departing from the spirit and scope of the invention as defined in
the following claims.
[0105] This application is based on Japanese Patent application JP
2003-295327, filed Aug. 19, 2003, the entire content of which is
hereby incorporated by reference.
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