JP2009226750A - Mold structure for imprint, imprinting method using mold structure for imprint, magnetic recording medium, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold structure for imprint showing high peelability of an imprint resist layer, high transfer durability and high transferability, and to provide an imprinting method showing improved transfer precision by using the mold structure for imprint, a magnetic recording medium showing improved recording characteristic and regeneration, and its manufacturing method. <P>SOLUTION: The mold structure 1 for imprint has a disk-like base plate 2 and a recess-projection part 3 having a plurality of projections 4 arranged on one surface, as the base surface, of the base plate wherein a peelable layer is formed on the recess-projection part, and an amount (MT) of a releasing agent contained in the peelable layer formed on the projections and an amount (MB) of a releasing agent contained in the peelable layer formed on the recesses satisfy the formula (1): MT>MB. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imprint mold structure, an imprint method using the imprint mold structure, a magnetic recording medium, and a manufacturing method thereof.

In recent years, hard disk drives excellent in high speed and cost performance have begun to be installed in portable devices such as mobile phones, small acoustic devices, and video cameras as the mainstay of storage devices.
As the market share of recording devices mounted on portable devices expands, it is necessary to meet the demand for further miniaturization and larger capacity, and a technique for improving recording density is required.
In order to increase the recording density of the hard disk drive, methods of narrowing the data track interval in the magnetic recording medium and narrowing the width of the magnetic head have been conventionally used.
However, by narrowing the data track interval, the influence of magnetism (crosstalk) between adjacent tracks and the influence of thermal fluctuation cannot be ignored, and the recording density is limited.
On the other hand, there is a limit in improving the surface recording density by reducing the width of the magnetic head.

Therefore, a magnetic recording medium called a discrete track medium has been proposed as means for solving the noise caused by the crosstalk (see Patent Documents 1 and 2). The discrete track media has a discrete structure in which non-magnetic guard band regions are provided between adjacent tracks to magnetically separate individual tracks, thereby reducing magnetic interference between adjacent tracks.
Further, as means for solving the demagnetization due to the thermal fluctuation, a magnetic recording medium called a patterned medium in which individual bits for signal recording are provided in a predetermined shape pattern has been proposed (Patent Document 3). reference).

When manufacturing the above discrete track media or patterned media, a resist pattern forming mold (hereinafter sometimes referred to as “mold”) is used to form a desired resist layer formed on the surface of the magnetic recording medium. An imprinting method (imprint process) for transferring the pattern is used (see Patent Document 4).
Specifically, this imprinting method applies a thermoplastic resin or a photocurable resin as an imprint resist on a substrate to be processed, and a desired resin is applied to the applied resin. The mold processed into a shape is adhered and pressed, the resin is cured by heating or light irradiation, and the mold is peeled off to form a pattern corresponding to the pattern formed in the mold. This is a method of obtaining a desired magnetic recording medium by performing patterning by dry or wet etching using a pattern as a mask (hereinafter also referred to as a resist mask).

  Since this imprinting method requires a number of transfer processes from the viewpoint of cost reduction, at least several hundred to several tens of thousands of transfer durability is required for the imprint mold structure.

  Therefore, in order to improve the transfer durability, a technique is disclosed in which a rigid body such as a silicon substrate is employed for the imprint mold structure (see Patent Document 5 and Non-Patent Document 1). According to these documents, it is described that very high pattern accuracy can be obtained, and transfer of a fine pattern up to the order of submicron and several tens of nanometers can be realized.

On the other hand, a technique for improving transfer durability by forming a release layer on the uneven portion (uneven pattern) of the imprint mold structure so as to be easily peeled off from the imprint resist is disclosed (Patent Document 6). And Patent Document 7). In addition, a technique for improving the peelability between the imprint resist and the imprint mold structure using an imprint resist having a peeling function has been proposed (see Patent Document 8).
The present inventors formed a resist mask by using a mold having a release layer formed by adsorbing a fluorine-modified release functional material (hereinafter, also referred to as a release agent) on the surface. Later, it was confirmed that the releasability between the mold and the imprint resist layer was remarkably improved.
However, after that, when patterning the magnetic layer and the nonmagnetic layer on the substrate of a large number of magnetic recording media using the formed resist mask, the magnetic region is etched in the region to be etched to embed the nonmagnetic layer. There is a problem that the material may remain and transferability is deteriorated.

  Accordingly, an imprint mold structure not only having high releasability and transfer durability with respect to the imprint resist layer but also high transferability, and imprint with improved transfer accuracy by using the imprint mold structure A method, a magnetic recording medium with improved recording characteristics and reproduction characteristics, and a method for manufacturing the same have not yet been realized, and it is desired to provide them.

Japanese Patent Laid-Open No. 56-119934 JP-A-2-201730 JP-A-3-22211 JP 2004-221465 A US Pat. No. 5,772,905 US Pat. No. 6,309,580 Japanese Patent Laid-Open No. 2004-288883 JP 2006-54300 A S. Y. Chou, et al. , Appl. Phys. Lett. , Vol. 67, 3314, 1995

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention improves imprinting accuracy by using an imprint mold structure that not only has high peelability and transfer durability with respect to the imprint resist layer, but also high transferability, and the imprint mold structure. It is an object of the present invention to provide an imprint method, a magnetic recording medium with improved recording characteristics and reproduction characteristics, and a method for manufacturing the same.

In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. In other words, in the magnetic layer processing step, the state of the processed region of the magnetic layer was confirmed, and the residual film thickness of the concave portion of the resist mask pattern after the imprint process was thicker, particularly at the boundary with the convex portion. It was found that this resist mask pattern defect affects the processing of the magnetic layer.
Further, as a result of detailed analysis of the mold causing the pattern defect of the resist mask, it was confirmed that the end of the convex portion on the mold was characteristically damaged and the corner portion was rounded.
When such a phenomenon was verified, it was found that the volume shrinkage of the resist during curing was a major factor. Specifically, the resist that has flowed into the uneven pattern of the mold shrinks isotropically when it is cured. In particular, in the concavo-convex portion (concave / convex pattern), a force due to volume contraction acts in a direction substantially perpendicular to the pattern flat surface on the flat surface of the convex portion, the flat surface of the concave portion, and the inclined surface between the concavo-convex portions. On the other hand, at the end of the convex portion, the contraction force of both the flat surface and the inclined surface of the convex portion acts, the shearing force acts on the end portion of the convex portion, and the end of the convex portion is characteristically It was estimated that pattern degradation occurred.
Therefore, by strengthening the peeling function at the convex portion formed on the surface of the mold, particularly at the end of the convex portion, not only the peelability to the imprint resist layer is high, but also transferability and transfer durability. This is a finding that an imprint mold structure can be provided.
In addition, the said uneven | corrugated inclined surface is a part formed by the uneven | corrugated boundary end 2 and the uneven | corrugated boundary end 3 defined as follows.
The uneven boundary edge 2 is a 1/0 boundary when an image is binarized with 95% of the maximum luminance as a threshold in the SEM image of the uneven portion of the mold structure.
Similarly, the uneven boundary edge 3 is a 1/0 boundary when the image is binarized using 5% of the maximum luminance as a threshold in the SEM image of the uneven portion of the mold structure.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A disk-shaped substrate, and an uneven portion formed by arranging a plurality of protrusions on one surface of the substrate on the basis of the surface, and a release layer on the uneven portion The amount (MT) of the release agent contained in the release layer formed on the convex portion and the amount of the release agent (MT) contained in the release layer formed on the concave portion formed between the convex portions ( MB) is an imprint mold structure characterized by satisfying the following mathematical formula (1).
MT> MB ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (1)
In the imprint mold structure according to <1>, the amount of the release agent contained in the release layer formed on the convex portion is greater than the amount of the release agent contained in the release layer formed on the concave portion. The transfer durability against the shearing force at the end of the convex portion, which is relatively subject to load when peeling from the imprint resist, is improved, and the imprint resist corresponding to the concave portion (convex portion) The transferability to) is improved.
<2> When the amount of the release agent at the end of the convex portion is MTE and the amount of the release agent at the central portion of the convex portion is MTO, <1> that satisfies the following formula (2) and formula (3) It is the mold structure for imprint described.
MTE> MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (2)
MT = αMTE + (1−α) MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (3)
However, in the above formula (3), 0.01 ≦ α ≦ 0.12.
<3> The imprint mold structure according to any one of <1> to <2>, wherein MTE / MTO satisfies the following mathematical formula (4).
1.05 <MTE / MTO <1.3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (4)
<4> A method for producing an imprint mold structure according to any one of <1> to <3>, wherein a release layer is formed on an uneven portion of the imprint mold structure. A method for producing an imprint mold structure, comprising: a step; and a release agent amount control step for controlling the amount of the release agent contained in the release layer by irradiating the release layer with ultraviolet rays. .
<5> The imprint mold structure according to any one of <1> to <3> is pressed against an imprint resist layer made of an imprint resist composition formed on a substrate of a magnetic recording medium. The imprint method includes at least a transfer step of transferring a concavo-convex pattern based on the concavo-convex portion formed on the imprint mold structure.
<6> The imprint method according to <5>, wherein the volume shrinkage ratio of the imprint resist layer is 21% or less.
<7> The imprint mold structure according to any one of <1> to <3> is pressed against an imprint resist layer formed on a substrate of a magnetic recording medium. A step of transferring a concavo-convex pattern based on the concavo-convex portion formed on the substrate, and etching the magnetic layer formed on the surface of the substrate of the magnetic recording medium using the imprint resist layer to which the concavo-convex pattern is transferred as a mask. At least a magnetic pattern portion forming step for forming a magnetic pattern portion based on the concavo-convex pattern in the magnetic layer, and a nonmagnetic pattern portion forming step for embedding a nonmagnetic material in a concave portion formed on the magnetic layer. This is a method of manufacturing a magnetic recording medium.
<8> The method for producing a magnetic recording medium according to <7>, wherein the volume shrinkage of the imprint resist layer is 21% or less.
<9> A magnetic recording medium produced by the method for producing a magnetic recording medium according to any one of <7> to <8>.

  According to the present invention, the imprint mold structure not only has high peelability and transfer durability with respect to the imprint resist layer but also high transferability, and the transfer accuracy is improved by using the imprint mold structure. In addition, an imprint method, a magnetic recording medium with improved recording characteristics and reproduction characteristics, and a manufacturing method thereof can be provided.

The imprint mold structure of the present invention will be described below with reference to the drawings.
(Imprint mold structure)
FIG. 1 is a partial cross-sectional perspective view showing a configuration in an embodiment of an imprint mold structure according to the present invention.
As shown in FIG. 1, the imprint mold structure 1 of the present embodiment has a convex portion 4 on one surface 2 a (hereinafter sometimes referred to as a reference surface 2 a) of a disk-shaped substrate 2. It has the uneven | corrugated | grooved part 3 formed in multiple numbers by predetermined spacing. A release layer 6 is laminated on the uneven portion 3 in this order.
Here, the convex part 4 is comprised from the side wall part 4a which is the surface standing upright substantially perpendicular | vertical with respect to the board | substrate 2, and the top part 4b which connects the side wall part 4a which mutually opposes in the surface substantially parallel to the surface 2a. Is done.
Moreover, it is preferable that the cross-sectional shape of the convex part 4 in the surface orthogonal to the direction where the convex part 4 is arranged makes a rectangle.
In addition, the cross-sectional shape of the said convex part 4 can select arbitrary shapes by controlling the etching process mentioned later according to the objective.
On the other hand, the concave portion 5 is formed between two adjacent convex portions 4, and is constituted by two side wall portions 4a, 4a facing each other so as to be separated from each other, and the surface 2a.
Hereinafter, in the description of the present embodiment, “cross section (shape)” refers to a cross section (shape) in the radial direction of the concentric circle (direction in which the convex portions 4 are arranged) unless otherwise specified.

Moreover, it is preferable that the thickness of the board | substrate 2 is 0.01 mm or more and less than 0.5 mm.
Moreover, the height (depth of the recessed part 5) H of the convex part 4 of the board | substrate 2 has the preferable range of 10-800 nm, and its 30-300 nm is more preferable.
Further, as the material of the substrate 2, a metal such as nickel is preferably used.

The end portion of the convex portion is a region having an area of 25 nm ² in a region formed by the uneven boundary end 1 and the uneven boundary end 2.
The central portion of the convex portion is a region having an area of 25 nm ² at an intermediate point (region) formed by the concave and convex boundary ends 2 on both sides of the convex pattern.
The uneven boundary edge 1 and the uneven boundary edge 2 are obtained from the SEM observation result of the uneven portion of the mold structure performed before the activation process / peeling layer formation.
The uneven boundary edge 1 is a 1/0 boundary when the image is binarized using 80% of the maximum luminance as a threshold in the observed SEM image.
The concavo-convex boundary edge 2 is a 1/0 boundary when the image is binarized with 95% of the maximum luminance as a threshold in the SEM image of the concavo-convex portion of the mold structure as described above.
In addition, MTO value (amount of release agent at the center of the convex pattern), MTE value (amount of release agent at the end of the convex pattern), MB value (of the release agent in the release layer formed on the concave pattern) Amount) and MT value (amount of release agent in the release layer formed on the protrusion pattern), 10 end portions of the protrusions and 10 center portions of the protrusions, respectively, Use the average of 10 locations.

<Peeling layer>
The imprint mold structure 1 of the present invention includes an amount (MT) of a release agent contained in a release layer formed on the convex portion 4 and a release formed on the concave portion 3 formed between the convex portions 4. The amount (MB) of the release agent contained in the layer preferably satisfies the following mathematical formula (1).
MT> MB ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (1)
In addition, the said Numerical formula (1) is obtained from the result of the experiment conducted by changing the conditions of release agent. In the above mathematical formula (1), if MT <MB, a resist layer having a sufficient thickness cannot be secured in the concave portion of the mold pattern, and the processing failure of the magnetic layer may occur. In addition, the mold protrusion is not sufficiently peeled off, which may cause damage to the mold pattern.

The imprint mold structure 1 of the present invention has the following mathematical formula (2) when the amount of the release agent at the end of the convex portion is MTE and the amount of the release agent at the central portion of the convex portion is MTO. It is preferable to satisfy Expression (3).
MTE> MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (2)
MT = αMTE + (1−α) MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (3)
However, in the above formula (3), 0.01 ≦ α ≦ 0.12.
In addition, the said Numerical formula (2) and (3) is obtained from the result of the experiment conducted by changing the conditions of release agent. If the above mathematical formulas (2) and (3) are not satisfied, the peeling state of the mold convex end portion is insufficient, which may cause pattern damage.

In the imprint mold structure 1 of the present invention, MTE / MTO preferably satisfies the following mathematical formula (4).
1.05 <MTE / MTO <1.3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (4)
In addition, the said Numerical formula (4) is obtained from the result of the experiment conducted by changing the conditions of release agent. If the above mathematical formula (4) is not satisfied, the peeling state of the mold convex portion is insufficient, and pattern breakage may be caused, and stable NIL cannot be achieved.

<< Measurement Method of Amount of Release Agent >>
Here, an example of a method for measuring the amount of the release agent will be described.
First, on the flat substrate (4 inch-Si wafer), the same release agent used for the release layer formed on the mold is formed by dip coating. Thereafter, the spectral intensity (I_REF) of the fluorine element is detected using a micro-Auger apparatus (PHI700, manufactured by ULVAC-PHI) with respect to the sample applied and formed under the same conditions as when the release layer was formed.
Then, an ellipsometer (DHA-XA / S4, manufactured by Mizoji Optical Co., Ltd.) is used for the same sample, and the thickness (THR) of the release layer is derived.
For the mold, the fluorine element spectrum intensity is mapped to a 1 μm square region by the same evaluation method as described above. Then, the concave / convex shape is observed with a simple SEM installed in the apparatus, the SEM image is associated with the fluorine element spectrum intensity map, the central portion and the end portion of the concave / convex pattern are determined, and the fluorine amount at a predetermined location is derived. To do.
Specifically, when the fluorine amount at the end of the convex pattern is “IF_MTE”, the fluorine amount at the central portion of the convex pattern is “IF_MTO”, and the fluorine amount at the central portion of the concave pattern is “IF_MB”, The amount MT of the release agent in the release layer formed on the pattern part, the amount MB of the release agent in the release layer formed on the pattern part, the amount (MTE) of the release agent at the end of the convex part pattern, and the convex part The amount (MTO) of the release agent in the central portion of the pattern is derived by converting into a thickness by the following formula.
MT = MTE + MTO
MB = (THR / I_REF) × IF_MB
MTE = (THR / I_REF) × IF_MTE
MTO = (THR / I_REF) × IF_MTO

<< Release agent >>
The release agent is preferably a material having a peeling function with respect to the workpiece, and examples of the material having a peeling function with respect to the workpiece include known fluororesins, hydrocarbon-based lubricants, and fluorine-based materials. A lubricant, a fluorine-based silane coupling agent, or the like can be used.
Examples of the fluororesin include PTFA, PFA, FEP, ETFE and the like.
Examples of the hydrocarbon lubricant include carboxylic acids such as stearic acid and oleic acid, esters such as butyl stearate, sulfonic acids such as octadecyl sulfonic acid, phosphate esters such as monooctadecyl phosphate, stearyl alcohol, oleyl Examples thereof include alcohols such as alcohol, carboxylic acid amides such as stearamide, and amines such as stearylamine.
Examples of the fluorine-based lubricant include a lubricant in which part or all of the alkyl group of the hydrocarbon-based lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group.
As the perfluoropolyether group, a perfluoromethylene oxide polymer, a perfluoroethylene oxide polymer, a perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) n, a perfluoroisopropylene oxide polymer ( CF (CF ₃ ) CF ₂ O) n or a copolymer thereof.
The fluorine-based silane coupling agent has at least one, preferably 1 to 10 alkoxysilane groups and chlorosilane groups in the molecule, and preferably has a molecular weight of 200 to 500,000.
Examples of the alkoxysilane group include —Si (OCH ₃ ) ₃ group, —Si (OCH ₂ CH ₃ ) ₃ group, and —Si (OCH ₃ ) ₃ group. As the chlorosilane group, —Si ( Cl) ₃ groups and the like. Specifically, heptadecafluoro-1,1,2,2-tetra-hydrodecyltrimethoxysilane, pentafluorophenylpropyldimethylchlorosilane, tridecafluoro-1,1,2,2-tetra-hydrooctyltriethoxy Materials such as silane and tridecafluoro-1,1,2,2-tetra-hydrooctyltrimethoxysilane.

  As mentioned above, although the form (data pattern) of the uneven | corrugated | grooved part 3 formed along the circumferential direction of the board | substrate 2 was shown as an uneven | corrugated | grooved part provided in the mold structure for imprints of this invention, As a form, you may apply to the form (servo pattern) which formed the uneven | corrugated | grooved part by arranging a convex part radially from the center part of the board | substrate 2. FIG.

(Method for producing imprint mold structure)
Hereinafter, a manufacturing method in an embodiment of an imprint mold structure will be described with reference to the drawings.

―Making master disc―
2A and 2B are cross-sectional views illustrating a method for producing a mold structure according to the second embodiment. As shown in FIG. 2A, first, a photoresist solution such as PMMA is applied on a disk-shaped Si substrate 10 by a spin coater or the like to form a photoresist layer 21 (photoresist layer forming step).
Thereafter, while rotating the Si substrate 10, a laser beam (or electron beam) modulated in accordance with the servo signal is irradiated (drawing step).
Thereafter, a predetermined pattern on the entire surface of the photoresist, for example, a pattern (servo pattern) corresponding to a servo signal extending linearly from the center of rotation to each track is exposed to a portion corresponding to each frame on the circumference (exposure). Process).
Thereafter, the photoresist layer 21 is developed, the exposed portion is removed, and selective etching such as RIE (reactive ion etching) is performed using the pattern of the removed photoresist layer 21 as a mask (etching process). A master 11 having a part is obtained.

Next, as shown in FIG. 2B, the conductive film 22 made of Ni is formed by performing sputtering using Ni as a target on the uneven portion formed on the surface of the master 11.
Thereafter, the conductive film 22 is formed in a predetermined thickness on the conductive film 22 by plating to produce a Ni substrate 23 having a positive concavo-convex pattern and peeled off from the master 11.

[Formation of release layer]
A release layer composition is prepared, and the release layer composition is applied onto the positive concavo-convex pattern to form the release layer 6.
As described above, the imprint mold structure 1 is obtained.

<Method of manufacturing magnetic recording medium>
Hereinafter, a manufacturing method for manufacturing a magnetic recording medium such as a discrete track medium or a patterned medium using the imprint mold structure according to the present invention will be described with reference to the drawings.

[Transfer process]
As shown in FIG. 3, an imprint mold is formed on a magnetic recording medium substrate 40 in which a magnetic layer 50 and an imprint resist layer 24 formed by applying an imprint resist solution such as PMMA are formed in this order. By pressing and pressing the structure 1, the pattern of the protrusions 4 formed on the imprint mold structure 1 is transferred to the imprint resist layer 24.

<< imprint resist layer >>
The imprint resist layer is a layer formed by applying an imprint resist composition (hereinafter also referred to as “imprint resist solution”) to a substrate of a magnetic recording medium.
There is no restriction | limiting in particular as the imprint resist layer 25, Although it can select suitably from well-known things according to the objective, For example, the imprint containing at least any one of a thermoplastic resin and a photocurable resin is used. It is a layer formed by applying a resist composition (hereinafter also referred to as “imprint resist solution”) to the substrate 40 of the magnetic recording medium. Moreover, as the imprint resist composition for forming the imprint resist layer 13, for example, a novolac resin, an epoxy resin, an acrylic resin, an organic glass resin, an inorganic glass resin, or the like is used.
The thickness of the imprint resist layer is preferably 5% or more and less than 200% with respect to the height of the convex portion formed on the surface 2a of the mold 1. If it is less than 5%, the resist amount is insufficient, and a desired resist pattern cannot be formed.
The thickness of the imprint resist layer can be measured, for example, by partially removing the resist from the substrate of the magnetic recording medium coated with the resist and measuring the step after the peeling with an AFM apparatus (Dimension 5000, manufactured by Biko Japan). it can.

[Viscosity of imprint resist composition]
The viscosity of the imprint resist composition is measured using, for example, an ultrasonic viscometer.

<Method for producing imprint mold structure>
Hereinafter, an example of a method for producing an imprint mold structure according to the present invention will be described with reference to the drawings. The imprint mold structure according to the present invention may be manufactured by a manufacturing method other than the following manufacturing method.

―Making master disc―
2A and 2B are cross-sectional views illustrating a method for producing the mold structure 1. As shown in FIG. 2A, first, a photoresist solution such as a novolak resin or an acrylic resin is applied on the Si base material 10 by spin coating or the like to form a photoresist layer 21.
After that, while rotating the Si substrate 10, a laser beam (or electron beam) modulated in accordance with the servo signal is irradiated, and a predetermined pattern is applied to the entire surface of the photoresist, for example, each track is linear from the rotation center to the radial direction. A pattern corresponding to the servo signal extending to is exposed at a portion corresponding to each frame on the circumference.
Thereafter, the photoresist layer 21 is developed, the exposed portion is removed, and selective etching is performed by RIE or the like using the pattern of the removed photoresist layer 21 as a mask to obtain the master 11 having an uneven shape.

As a method for producing a mold for producing a mold from the master 11, a plating method, a nanoimprint method, or the like can be used.
The mold production method by the plating method is as follows.
First, a conductive layer (not shown) is formed on the surface of the master 11.
As a method for forming the conductive film, a vacuum film forming method (sputtering, vapor deposition, etc.), an electroless plating method, or the like can be generally used.
As the material of the conductive layer, a metal or alloy containing at least one element among Ni, Cr, W, Ta, Fe, and Co can be used, and Ni, Co, FeCo alloy, and the like are preferable. Further, a non-metallic material such as TiO showing conductivity can also be used as the conductive layer.
The thickness of the conductive layer is preferably in the range of 5 nm to 30 nm, and more preferably in the range of 10 nm to 25 nm.
Using the master on which the conductive layer is formed, a metal and an alloy material are laminated by plating to form a predetermined thickness, and then the plating base is peeled off from the master 11 to form a mold.
Here, as the plating material constituting the mold, Ni, Cr, FeCo alloy or the like can be used, and those using Ni material are particularly preferable.
Further, the thickness of the mold 1 after peeling is preferably in the range of 30 μm to 500 μm, and more preferably in the range of 45 μm to 300 μm. If it is less than 30 μm, the rigidity of the mold is lowered and the mechanical properties cannot be secured.
In addition, by performing the transfer process (NIL, nanoimprint lithography) many times, the mold 1 itself may be deformed, and the practical characteristics may be significantly reduced. Therefore, since the rigidity becomes too high when the thickness of the mold is 500 μm or more, the close contact between the mold 1 during NIL and the substrate 40 of the magnetic recording medium cannot be ensured.
In order to secure adhesion, it is necessary to increase the adhesion pressure, so that a fatal shape defect occurs between the mold 1 and the substrate 40 of the magnetic recording medium when foreign matter or the like is mixed.

The mold 1 may be duplicated using the mold as the master 11.
The mold replication method using the nanoimprint method is as follows.
As shown in FIG. 2B, the master 11 is applied to the substrate 40 on which the imprint resist layer 25 formed by applying an imprint resist solution containing a thermoplastic resin or a photocurable resin is formed on one surface. The pattern of the convex portions formed on the master 11 is transferred to the imprint resist layer 25 by pressing.

Here, the material of the substrate 40 is not particularly limited as long as it is a material having optical transparency and functioning as the mold structure 1, and is appropriately selected according to the purpose. SiO ₂ ) and organic resins (PET, PEN, polycarbonate, low melting point fluororesin) and the like.
The “having light transmittance” specifically means that light is incident from the other surface of the substrate 40 so as to be emitted from one surface where the imprint resist layer 25 is formed on the substrate 40. In this case, it means that the imprint resist solution is sufficiently cured, and at least the light transmittance of light having a wavelength of 400 nm or less from the other surface to the one surface is 50% or more. .
The “strength functioning as a mold structure” means that the imprint resist layer 25 formed on the substrate 40 is pressed against the imprint resist layer 25 under the condition that the average surface pressure is 1 kgf / cm ² or more. Also means strength that does not break in a peelable manner.

―Curing process―
Thereafter, the transferred pattern is cured by applying heat to the imprint resist layer 25 or irradiating ultraviolet rays or the like. When the pattern is cured by irradiating with ultraviolet rays, the pattern may be cured after the mold structure and the magnetic recording medium are peeled off and then irradiated with ultraviolet rays.

―Pattern formation process―
Thereafter, selective etching is performed by RIE or the like using the transferred pattern as a mask to obtain a mold structure 1 having an uneven shape. Alternatively, the mold structure 1 may be formed by forming an inorganic material on the surface of the substrate, forming an inorganic material mask based on the resist mask, and etching the substrate using the inorganic material mask. .

(Magnetic recording medium)
Hereinafter, a magnetic recording medium such as a discrete track medium and a patterned medium manufactured using the imprint mold structure according to the present invention will be described with reference to the drawings. However, the magnetic recording medium according to the present invention may be manufactured by a manufacturing method other than the following manufacturing method as long as it is manufactured using the imprint mold structure according to the present invention.

  As shown in FIG. 3, the mold structure 1 is pressed against a substrate 40 of a magnetic recording medium in which a magnetic layer 50 and an imprint resist layer 25 formed by applying an imprint resist solution are formed in this order. By applying pressure, the pattern of the uneven portion 3 in the data area and the uneven portion 4 in the servo area 120 formed on the mold structure 1 is transferred to the imprint resist layer 25.

Here, as the imprint resist layer 25 in the production of the magnetic recording medium, the same imprint resist composition as the imprint resist layer 24 in the production of the imprint mold structure may be employed.
Hereinafter, unless otherwise specified, the imprint resist layer and the imprint resist composition refer to the imprint resist layer 25 in the production of the magnetic recording medium and the imprint resist composition that forms the imprint resist layer 25. And

Thereafter, an etching process is performed using the imprint resist layer 25 to which the pattern of the uneven portion 3 in the data region and the uneven portion 4 in the servo region 120 is transferred as a mask, and the uneven portion formed on the mold structure 1 is formed. After forming a concavo-convex pattern based on the magnetic layer 50 and embedding a nonmagnetic material in the concave portion to form the nonmagnetic layer 70 and planarizing the surface, other steps such as forming a protective film are performed as necessary. To obtain the magnetic recording medium 100.
The etching step is a step of forming a concavo-convex shape based on the resist concavo-convex pattern shape formed in the imprint resist layer 25 in the data region on the magnetic layer 50 in the data region.
As a method for forming the irregularities, techniques such as ion beam etching, reactive chemical etching, and wet etching can be used.
Ar can be used as a process gas in ion beam etching, and CO + NH ₃ , chlorine gas, or the like can be used as an etchant in reactive chemical etching.
As the other steps, if necessary, the recesses of the magnetic layer are filled with SiO ₂ , carbon, alumina; a polymer such as polymethyl methacrylate (PMMA) or polystyrene (PS); a nonmagnetic material such as lubricating oil. Examples thereof include a step, a step of flattening the surface, a step of forming a protective film with DLC (diamond-like carbon) or the like on the flattened surface, and finally a step of applying a lubricant.

FIG. 5 is a plan view showing the configuration of the magnetic recording medium of the present invention.
As shown in FIG. 5, the magnetic recording medium of the present invention produced as described above has a magnetic pattern of a plurality of data areas formed concentrically on a surface of a substrate 40 at predetermined intervals. The portion 51 and the magnetic pattern portions 52 of the plurality of servo regions formed at predetermined intervals in the radial direction of the substrate 2 are formed separated by the nonmagnetic layer 70.

Further, on the surface of the substrate 40, the region where the magnetic pattern portion 51 of the data region is formed is the data region 130, and the region where the magnetic pattern portion 52 of the servo region is formed on the surface is the servo region 140. .
In such a configuration of the data area 130 and the servo area 140, a plurality of servo areas 140 are formed at substantially equal intervals in the circumferential direction so as to divide the data area 130.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Example 1
<Preparation of imprint mold structure>
<< Preparation of master disk >>
An electron beam resist was applied to a thickness of 100 nm on a disk-like Si substrate having a diameter of 8 inches by using a spin coating method.
By exposing and developing a desired pattern with a rotary electron beam exposure apparatus, the electron beam resist having a concavo-convex pattern is formed on a Si substrate.
Using the electron beam resist having a concavo-convex pattern as a mask, a reactive ion etching process is performed on the Si substrate to form a concavo-convex shape on the Si substrate.
The remaining electron beam resist was removed by washing with a soluble solvent and dried to obtain a master.

Here, the uneven pattern is roughly classified into an uneven pattern in the data portion and an uneven pattern in the servo portion.
The data part was a concavo-convex pattern having a convex part width: 500 nm and a concave part width: 300 nm (track pitch = 800 nm).
The servo unit has a reference signal length of 200 nm, a total number of sectors of 128, and includes a preamble part (45 bits), a SAM part (10 bits), a SectorCode part (8 bits), a CylinderCode part (32 bits), and a Burst part. Yes.
The SAM portion is “0000101011”, and the uneven pattern in the SectorCode portion is formed by using the binary conversion, and the uneven pattern in the cylinder code portion is formed by using the Gray conversion, and finally by using the Manchester conversion. It is formed.
The concave / convex pattern in the Burst portion is a general phase burst signal (16 bits).

Thereafter, a novolac resist (microresist company mr-I 7000E) was formed to 100 nm on a quartz substrate by spin coating (3,600 rpm).
Then, using the master as a mold, nanoimprinting is performed. Based on the uneven resist pattern after nanoimprinting, an imprint mold structure 1 was obtained by RIE using CHF ₃ as an etchant.

  A release agent (EGC-1720 manufactured by Sumitomo 3M) was applied to the surface of the produced imprint mold structure 1 by a wet method to form a release layer. The pulling speed was 1 mm / sec.

<Control of amount of release agent on surface of convex pattern>
The amount of release agent in the release layer can be controlled by changing the activation state of the mold surface. As a method of changing the activation state, for example, there is a method of irradiating ultraviolet rays (ultraviolet irradiation method). In the ultraviolet irradiation method, the activation state of the mold surface can be controlled by adjusting the light source / mold irradiation distance, the irradiation time, and the light source input power. For example, if the ultraviolet irradiation time is lengthened, the input power is increased, and the irradiation distance is shortened, the ultraviolet integrated irradiation amount is increased, and the adsorption efficiency of the release agent to the mold surface is improved. In particular, the adjustment of the irradiation distance and the adjustment of the incident angle of ultraviolet rays are effective in improving the adsorption efficiency of the release agent.
Examples of the apparatus used include a desktop optical surface treatment apparatus PL16-110 (manufactured by Sen Special Light Source Co., Ltd.).
Specifically, the surface of the imprint mold structure 1 before the release agent is formed is irradiated with ultraviolet rays. The conditions for irradiating with ultraviolet rays are: light source / mold irradiation distance: 10 mm, irradiation time: 2 min, light source input power: 18 mW / cm ² .
Note that the amount of the release agent in the release layer can also be controlled by irradiating the release layer with oxygen plasma after the release layer is formed. This is because when the release layer is irradiated with oxygen plasma, the release agent in the release layer is decomposed and the same effect as when the release agent is removed can be obtained.

<Preparation of magnetic recording medium>
Each layer was formed on a 2.5-inch glass substrate by the following procedure to produce a magnetic recording medium.
The produced magnetic recording medium has a soft magnetic layer, a first nonmagnetic alignment layer, a second nonmagnetic alignment layer, a magnetic layer (sometimes referred to as a “magnetic recording layer”), a protective layer, and a lubricant layer. It is formed sequentially.
The soft magnetic film, the first nonmagnetic alignment layer, the second nonmagnetic alignment layer, the magnetic recording layer, and the protective layer were formed by a sputtering method, and the lubricant layer was formed by a dip method.

<Formation of soft magnetic layer>
As the soft magnetic layer, a layer made of CoZrNb was formed with a thickness of 100 nm.
Specifically, the glass substrate was placed facing the CoZrNb target, Ar gas was introduced to a pressure of 0.6 Pa, and a film was formed at DC 1,500 W.

<Formation of first nonmagnetic alignment layer>
A Ti layer having a thickness of 5 nm was formed as the first nonmagnetic alignment layer.
Specifically, the first nonmagnetic alignment layer is placed opposite to the Ti target, Ar gas is flowed to a pressure of 0.5 Pa, discharged at DC 1,000 W, and a thickness of 5 nm is obtained. A Ti seed layer was formed.

<Formation of Second Nonmagnetic Orientation Layer>
Thereafter, a Ru layer having a thickness of 6 nm was formed as a second nonmagnetic alignment layer.
After the first nonmagnetic alignment layer is formed, it is placed facing the Ru target, Ar gas is introduced to a pressure of 0.5 Pa, discharge is performed at DC 1,000 W, and the thickness is 10 nm. A Ru layer was formed as the second nonmagnetic alignment layer.

<Formation of magnetic recording layer>
Thereafter, a CoCrPtO layer having a thickness of 15 nm was formed as a magnetic recording layer.
Specifically, it was placed facing the CoPtCr target, Ar gas containing 0.04% O ₂ was introduced at a pressure of 18 Pa, and discharged at DC 290 W to form a magnetic recording layer.

<Formation of protective layer>
After the magnetic layer was formed, it was placed facing the C target, Ar gas was flowed in so that the pressure became 0.5 Pa, discharged at DC 1,000 W, and the C protective layer was formed with a thickness of 4 nm.
The coercive force of the magnetic recording medium was 334 kA / m (4.2 kOe).
In addition, the first nonmagnetic material of the magnetic recording medium in this example is PtO.

<Formation of imprint resist layer>
An imprint resist layer was formed on the protective layer by spin coating (3,600 rpm) so that an acrylic resist (PAK-01-500, manufactured by Toyo Gosei Co., Ltd.) had a thickness of 100 nm. .

<Transfer process>
The substrate on which the imprint resist layer is formed is placed so that the surface on which the uneven portion of the mold is formed is opposed to the substrate, and the substrate on which the imprint resist layer is formed is adhered for 10 seconds at a pressure of 3 MPa. Then, ultraviolet rays were irradiated at 10 mJ / cm ² .
After completing the above steps, the mold was peeled from the substrate on which the imprint resist layer was formed.
Thereafter, by transferring a concavo-convex pattern based on the concavo-convex portion of the mold to the imprint resist layer, the imprint resist layer remaining in the concave portion of the concavo-convex pattern formed on the imprint resist layer is converted to O ₂ reactivity. It was removed by chemical etching. This O ₂ reactive chemical etching is performed so that the magnetic layer is exposed in the recess.

<Magnetic pattern part formation process>
After removing the imprint resist layer remaining in the concave portion, the concave and convex shape of the magnetic layer was processed.
As the processing of the magnetic layer, an ion beam etching method was used.
Specifically, Ar gas was used, the ion acceleration energy was 500 eV, and an ion beam was incident on the magnetic layer from the vertical direction.
After processing the magnetic layer in this way, the resist remaining on the magnetic layer (unprocessed portion) is removed by O ₂ reactive chemical etching.
Thereafter, a PFPE lubricant was applied to a thickness of 2 nm by a dip method.

<Nonmagnetic pattern part formation process>
After processing the magnetic layer, a SiO ₂ layer is formed by sputtering so that the layer containing the magnetic material has a thickness of 50 nm, and the magnetic layer and the nonmagnetic layer are surfaced by ion beam etching. The SiO ₂ layer was removed to be unity.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
On the flat substrate (4 inch-Si wafer), the same release agent used for the release layer formed on the mold is formed by dip coating. Thereafter, the spectral intensity (I_REF) of the fluorine element was detected using a micro-Auger apparatus (PHI700, manufactured by ULVAC-PHI) on a sample applied and formed under the same conditions as when the release layer was formed.
Then, an ellipsometer (DHA-XA / S4, manufactured by Mizoji Optical Co., Ltd.) was used for the same sample, and the thickness (THR) of the release layer was derived.
For the mold, the fluorine element spectrum intensity is mapped to a 1 μm square region by the same evaluation method as described above. Then, the concave / convex shape is observed with a simple SEM installed in the apparatus, the SEM image is associated with the fluorine element spectrum intensity map, the central portion and the end portion of the concave / convex pattern are determined, and the fluorine amount at a predetermined location is derived. did. The fluorine amount at the end of the convex pattern is “IF_MTE”, the fluorine amount at the central portion of the convex pattern is “IF_MTO”, and the fluorine amount at the central portion of the concave pattern is “IF_MB”.
In addition, the amount of material in the release layer formed on the surface of the mold was converted to thickness by the following relational expression.
MTO = (THR / I_REF) × IF_MTO
MTE = (THR / I_REF) × IF_MTE
MT = MTO + MTE
MB = (THR / I_REF) × IF_MB
The amount (MT) of the release agent in the release layer formed on the convex pattern, the amount MB of the release agent in the release layer formed on the concave pattern, and the end of the convex pattern, thus derived. Table 1 shows the results of the amount of release agent (MTE) and the amount of release agent (MTO) at the center of the convex pattern.

<Evaluation of uneven pattern shape and moldability>
One imprint process was performed 1,000 times in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium in the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated based on the following indices.

<< Evaluation of mold >>
Operation was performed using an AFM (Dimension 5000, manufactured by Nippon Beco Co., Ltd.) in an evaluation range of 1 μm square, and surface unevenness data was obtained. A threshold value was set at 80% of the pattern difference, and the dimensional variation of the side surface portion formed into a convex shape at this threshold value was evaluated with a standard deviation (1 μm square field of view). Measurements were made at 16 locations with a radius of 25 mm and approximately equal intervals on one disk, and the standard deviation (σ) within the entire measurement range was calculated. When the 3xσ value was 15 nm or less, “◯” was indicated, and when it was larger than 15 nm, “x” was indicated. In this evaluation, usable evaluation is “◯”. The evaluation results are shown in Table 1.

<< Evaluation of resist after nanoimprinting >>
It operates using AFM (Dimension 5000 by Nippon Beiko Co., Ltd.) in an evaluation range of 1 μm square, and obtains data of surface irregularities. A threshold value was set at 20% of the pattern difference, and the dimensional variation of the side surface portion formed in the concave shape with this threshold value was evaluated with a standard deviation (1 um square field of view). Measurements were made at 16 locations with a radius of 25 mm and approximately equal intervals on one disk, and the standard deviation (σ) within the entire measurement range was calculated. When the 3xσ value was 15 nm or less, “◯” was indicated, and when it was larger than 15 nm, “x” was indicated. In this evaluation, usable evaluations are “◯” and “Δ”.
During 10 times from the 990th to the 1,000th time, if “x” judgment is 3 or more, comprehensive judgment is made as “x”, and if it is 1 to 2 times, overall judgment is made as “△”, 0 pictures If so, it was comprehensively judged as “◯”. In this evaluation, usable evaluations are “◯” and “Δ”. The evaluation results are shown in Table 2.

<< Evaluation of convex part of magnetic layer >>
The uniformity of the magnetic layer convex portion width was evaluated for the data portion pattern. It operates using AFM (Dimension 5000 by Nippon Beiko Co., Ltd.) in an evaluation range of 1 μm square, and obtains data of surface irregularities. A threshold value was set at 80% of the pattern difference, and the dimensional variation of the side surface portion formed into a convex shape at this threshold value was evaluated with a standard deviation (1 μm square field of view). Measurements were made at 16 locations with a radius of 25 mm and approximately equal intervals on one disk, and the standard deviation (σ) within the entire measurement range was calculated. When the 3xσ value was 15 nm or less, “◯” was indicated, and when it was larger than 15 nm, “x” was indicated. In this evaluation, usable evaluation is “◯”.
During 10 times from the 990th to the 1,000th time, if “x” judgment is 3 or more, comprehensive judgment is made as “x”, and if it is 1 to 2 times, overall judgment is made as “△”, 0 pictures If so, it was comprehensively judged as “◯”. In this evaluation, usable evaluations are “◯” and “Δ”. The evaluation results are shown in Table 3.

(Example 2)
<Preparation of imprint mold structure>
In Example 1, the imprint mold structure of Example 2 was produced in the same manner as in Example 1 except that the pulling rate during formation of the release layer was set to 0.5 mm / sec.

<Preparation of magnetic recording medium>
A magnetic recording medium of Example 2 was produced in the same manner as in Example 1 except that the imprint mold structure produced in Example 2 was used.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
In the same manner as in Example 1, the thickness (THR) of the release layer was derived, the amount of release agent (MT) in the release layer formed on the convex pattern, and the release agent in the release layer formed on the concave pattern. Amount MB, the amount of release agent (MTE) at the end of the convex pattern, and the amount of release agent (MTO) at the center of the convex pattern. The results are shown in Table 1.

<Evaluation of uneven pattern shape and moldability>
Similarly to Example 1, 1,000 imprint processes were performed in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium at the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

(Example 3)
<Preparation of imprint mold structure>
In the control of the amount of the release agent on the surface of the convex pattern in Example 1, the imprint mold structure of Example 3 was prepared in the same manner as in Example 1 except that the distance between the light source and the mold was 15 mm. Produced.

<Preparation of magnetic recording medium>
A magnetic recording medium of Example 3 was produced in the same manner as in Example 1 except that the imprint mold structure produced in Example 3 was used.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
In the same manner as in Example 1, the thickness (THR) of the release layer was derived, the amount of release agent (MT) in the release layer formed on the convex pattern, and the release agent in the release layer formed on the concave pattern. Amount MB, the amount of release agent (MTE) at the end of the convex pattern, and the amount of release agent (MTO) at the center of the convex pattern. The results are shown in Table 1.

<Evaluation of uneven pattern shape and moldability>
Similarly to Example 1, 1,000 imprint processes were performed in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium at the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
<Preparation of imprint mold structure>
In the same manner as in Example 1, an imprint mold structure was produced.

<Preparation of magnetic recording medium>
In the formation of the imprint resist layer, an imprint resist composition was prepared by mixing an acrylic resist (PAK01-500, manufactured by Toyo Gosei Co., Ltd.) and dipentaerythritol hexaacrylate (DPHA) at 90:10. A magnetic recording medium of Example 4 was produced in the same manner as in Example 1 except that the print resist composition was used.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
In the same manner as in Example 1, the thickness (THR) of the release layer was derived, the amount of release agent (MT) in the release layer formed on the convex pattern, and the release agent in the release layer formed on the concave pattern. Amount MB, the amount of release agent (MTE) at the end of the convex pattern, and the amount of release agent (MTO) at the center of the convex pattern. The results are shown in Table 1.

<Evaluation of uneven pattern shape and moldability>
Similarly to Example 1, 1,000 imprint processes were performed in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium at the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
<Preparation of imprint mold structure>
An imprint mold structure of Comparative Example 1 was produced in the same manner as in Example 1 except that the amount of the release agent on the surface of the convex pattern in Example 1 was not controlled (ultraviolet irradiation).

<Preparation of magnetic recording medium>
A magnetic recording medium of Comparative Example 1 was produced in the same manner as in Example 1 except that the imprint mold structure produced above was used.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
In the same manner as in Example 1, the thickness (THR) of the release layer was derived, the amount of release agent (MT) in the release layer formed on the convex pattern, and the release agent in the release layer formed on the concave pattern. Amount MB, the amount of release agent (MTE) at the end of the convex pattern, and the amount of release agent (MTO) at the center of the convex pattern. The results are shown in Table 1.

<Evaluation of uneven pattern shape and moldability>
Similarly to Example 1, 1,000 imprint processes were performed in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium at the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
<Preparation of imprint mold structure>
In the control of the amount of the release agent on the surface of the convex pattern in Example 1, the distance between the light source and the mold was set to 50 mm, the processing time was set to 20 min, and then the mold was exposed to oxygen plasma for 1 min. In the same manner as in Example 1, an imprint mold structure of Comparative Example 2 was produced.

<Preparation of magnetic recording medium>
A magnetic recording medium of Comparative Example 2 was produced in the same manner as Example 1 except that the imprint mold structure produced above was used.

(Measurement and evaluation)
<Quantification of amount of release agent on convex pattern surface>
In the same manner as in Example 1, the thickness (THR) of the release layer was derived, the amount of release agent (MT) in the release layer formed on the convex pattern, and the release agent in the release layer formed on the concave pattern. Amount MB, the amount of release agent (MTE) at the end of the convex pattern, and the amount of release agent (MTO) at the center of the convex pattern. The results are shown in Table 1.

<Evaluation of uneven pattern shape and moldability>
Similarly to Example 1, 1,000 imprint processes were performed in one mold. The uneven pattern of the mold after the treatment, the uneven pattern of the magnetic recording medium at the 990th to 1,000th times, and the moldability of the resist after nanoimprinting were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, according to Examples 1 to 4 that satisfy the above formula (1), transferability, peelability, and transfer durability compared to Comparative Examples 1 and 2 that do not satisfy the above formula (1). It was possible to provide a mold structure for imprinting that is high.
Further, by using the imprint mold structures produced in Examples 1 to 4 that satisfy the above formula (1), the recording / reproduction characteristics are superior to those of Comparative Examples 1 and 2 that do not satisfy the above formula (1). Magnetic recording media could be provided.

  In the imprint mold structure of the present invention, the release layer formed on the imprint mold structure is formed under appropriate conditions in the convex part and the concave part of the imprint mold. A pattern can be formed on the imprint resist layer with a high yield without impairing the brittleness in the recess, which is suitable for manufacturing discrete media and patterned media.

FIG. 1 is a partial cross-sectional perspective view showing a configuration in an embodiment of an imprint mold structure of the present invention. FIG. 2A is a cross-sectional view showing an example of a method for producing an imprint mold structure of the present invention. FIG. 2B is a cross-sectional view showing an example of a method for producing an imprint mold structure of the present invention. FIG. 3 is a cross-sectional view showing a manufacturing method for manufacturing a magnetic recording medium using the imprint mold structure of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imprint mold structure 2 Substrate 2a Surface 3 Concavity and convexity 4 Convex part 5 Concave part 6 Peeling layer 10 Si substrate 11 Si master 21 Photoresist layer 22 Conductive film 23 Ni substrate 24 Imprint resist layer 40 Substrate of magnetic recording medium 50 Magnetic layer 70 Nonmagnetic layer 100 Magnetic recording medium

Claims (9)

A disk-shaped substrate, and an uneven portion formed by arranging a plurality of protrusions on one surface of the substrate with reference to the surface, and a release layer is formed on the uneven portion The amount (MT) of the release agent contained in the release layer formed on the convex portion, and the amount (MB) of the release agent contained in the release layer formed on the concave portion formed between the convex portions, Satisfies the following mathematical formula (1): an imprint mold structure.
MT> MB ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (1) The imprint according to claim 1, wherein when the amount of the release agent at the end of the convex portion is MTE and the amount of the release agent at the central portion of the convex portion is MTO, the following formula (2) and formula (3) are satisfied. Mold structure.
MTE> MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (2)
MT = αMTE + (1−α) MTO ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (3)
However, in the above formula (3), 0.01 ≦ α ≦ 0.12. The imprint mold structure according to claim 1, wherein MTE / MTO satisfies the following mathematical formula (4).
1.05 <MTE / MTO <1.3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (4)   It is a manufacturing method of the mold structure for imprints in any one of Claim 1 to 3, Comprising: The peeling layer formation process which forms a peeling layer on the uneven | corrugated | grooved part of the mold structure for imprints, In the said peeling layer, And a release agent amount control step of controlling the amount of release agent contained in the release layer by irradiating with ultraviolet rays.   The imprint mold structure according to any one of claims 1 to 3 is pressed against an imprint resist layer made of an imprint resist composition formed on a substrate of a magnetic recording medium. An imprint method comprising at least a transfer step of transferring a concavo-convex pattern based on a concavo-convex portion formed on a body.   The imprint method according to claim 5, wherein the volume shrinkage ratio of the imprint resist layer is 21% or less. An uneven portion formed on the imprint mold structure by pressing the imprint mold structure according to any one of claims 1 to 3 against an imprint resist layer formed on a substrate of a magnetic recording medium. A transfer process for transferring an uneven pattern based on
Using the imprint resist layer to which the concavo-convex pattern is transferred as a mask, the magnetic layer formed on the surface of the substrate of the magnetic recording medium is etched to form a magnetic pattern portion based on the concavo-convex pattern in the magnetic layer. A magnetic pattern portion forming step;
A non-magnetic pattern part forming step of embedding a non-magnetic material in the recess formed on the magnetic layer;
A method for producing a magnetic recording medium, comprising:   The method for manufacturing a magnetic recording medium according to claim 7, wherein the volume shrinkage ratio of the imprint resist layer is 21% or less.   A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to claim 7.