JP5325458B2 - Method for manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetic recording medium, for manufacturing a magnetic recording medium with high recording density and high productivity at a low cost. <P>SOLUTION: In the method of manufacturing the magnetic recording medium, the magnetic recording medium having a magnetically separated magnetic recording pattern is manufactured by using a resin mold and having an irregular pattern. The mold is manufactured through: a step to hold a liquid or gel curable resin material between a pair of facing substrates 11, 12, and to cure only the peripheral portion of the curable resin material so as to obtain a laminated body 10; a step to release one substrate 12 from the laminated body 10 so as to expose a layer 13 of the curable resin material; a step to press a master mold having the irregular pattern against the exposed layer 13 of the curable resin material; a step to cure the layer 13 of the curable resin material while pressing the master mold so as to obtain the resin mold; and a step to release the resin mold from the master mold. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a magnetic recording medium used in a hard disk device or the like.

  In recent years, the application range of magnetic recording devices such as magnetic disk devices, flexible disk devices, and magnetic tape devices has been remarkably increased and their importance has increased, and the recording density of magnetic recording media used in these devices has been significantly improved. It is illustrated. In particular, since the introduction of magnetoresistive (MR) heads and PRML technology, the increase in surface recording density has increased. In recent years, giant magnetoresistive (GMR) heads, tunneling magnetoresistive (TMR) heads, etc. have been introduced. It continues to increase at a rate of about 100% per year. However, the magnetic recording medium is required to further improve the recording density. For this reason, it is required to achieve a high coercivity, a high signal-to-noise ratio (SNR), and a high resolution of the magnetic layer. . In recent years, there has been an attempt to increase the surface recording density by increasing the track density at the same time as improving the linear recording density.

  In the latest magnetic recording apparatus, the track density has reached 110 kTPI. However, as the track density is increased, magnetic recording information between adjacent tracks interfere with each other, and the problem that the magnetization transition region in the boundary region becomes a noise source and the SNR is easily lost. This directly leads to a decrease in bit error rate, which is an obstacle to improvement in recording density.

In order to increase the surface recording density, it is necessary to make the size of each recording bit on the magnetic recording medium finer and ensure as much saturation magnetization and magnetic film thickness as possible for each recording bit. However, when the recording bits are miniaturized, the minimum magnetization volume per bit becomes small, and there arises a problem that the recording data is lost due to magnetization reversal due to thermal fluctuation.
In addition, since the distance between tracks is getting closer, magnetic recording devices are required to have extremely high precision track servo technology. At the same time, recording is performed widely, and playback is performed more than when recording to eliminate the influence of adjacent tracks as much as possible. In general, a method of narrowly executing is used. Although this method can minimize the influence between tracks, there is a problem that it is difficult to obtain a sufficient reproduction output, and it is difficult to secure a sufficient SNR.
As one of the methods to achieve such a problem of thermal fluctuation, SNR, or sufficient output, unevenness along the track is formed on the surface of the recording medium, or a nonmagnetic part is formed between adjacent tracks. Therefore, a method for increasing the track density by physically separating the recording tracks is being studied. Hereinafter, this method is referred to as a discrete track method.

  As an example of a discrete track type magnetic recording medium, there is a magnetic recording medium in which a magnetic recording medium is formed on a nonmagnetic substrate having a concavo-convex pattern formed on a surface, and a physically separated magnetic recording track and a servo signal pattern are formed. It is known (for example, refer to Patent Document 1). In this magnetic recording medium, a ferromagnetic layer is formed on a surface of a substrate having a plurality of irregularities on the surface via a soft magnetic layer, and a protective film is formed on the surface. In this magnetic recording medium, a magnetic recording area magnetically separated from the surroundings is formed in the convex area.

According to this magnetic recording medium, the occurrence of a domain wall in the soft magnetic layer can be suppressed, so that the influence of thermal fluctuation is difficult to occur, and there is no interference between adjacent signals, so that a high-density magnetic recording medium with less noise can be formed. ing.
The discrete track method includes a method in which a track is formed after a magnetic recording medium consisting of several thin films is formed, and a magnetic pattern is formed after a concave / convex pattern is formed directly on the substrate surface in advance or on a thin film layer for track formation. A method of forming a thin film of a recording medium is known (see, for example, Patent Document 2 and Patent Document 3). Among these, the former method is called a magnetic layer processing method, and the latter method is called a pre-embossing method.
The pre-embossing method has the advantage that the physical processing on the medium surface is completed before the medium is formed, so that the manufacturing process can be simplified and the medium is not easily contaminated in the manufacturing process. Since the uneven shape is inherited by the formed film, there is a problem in that the flying posture and flying height of the recording / reproducing head that performs recording / reproducing while floating on the medium are not stable.

  As a method for producing a magnetic recording medium by a magnetic layer processing method, a method using a nanoimprint method has been proposed. Specifically, it is a method of processing a continuous magnetic layer formed on a substrate into a magnetic recording track pattern or a bit pattern using a nanoimprint method.

Here, the nanoimprint method is a method of pressing a mold on which a concavo-convex pattern to be transferred is formed in advance against a material to be transferred and curing the material to be transferred while irradiating light or applying heat to the material to be transferred. It is a method of transcription.
The nanoimprint mold is, for example, an ultrafine uneven pattern of 100 nm or less formed on the surface of silicon or the like, and is very expensive. If this mold is worn and broken during the imprint process, it must be replaced with a new mold, which increases the cost of a magnetic recording medium product manufactured through the nanoimprint method. Therefore, when the nanoimprint process is applied industrially, a replica mold is manufactured for the purpose of preserving the master mold that serves as a master. That is, a master mold pattern is transferred to another material by a stamper device, so that a large number of replica molds are produced from one master mold.
Since this replica mold is produced in large quantities, it is inexpensive. Therefore, if the replica mold is used as a stamper for the nanoimprint process, even if the mold is broken, it can be replaced with another replica mold, and an expensive master mold can be preserved. As a result, a product having a fine uneven pattern can be manufactured at a low cost by the nanoimprint method.
As a replica mold manufactured by such a method, it is considered to use a resin mold. For example, a method of transferring a fine pattern using a photocuring reaction (see, for example, Non-Patent Document 1), photocuring thereof. A method of suppressing time shrinkage is disclosed (for example, see Patent Document 1).
JP 2004-164692 A JP 2004-178793 A JP 2004-178794 A JP 2005-120447 A Stephen Y. Chou et al., “Applied Physics Letter”, American Physical Society, Vol. 67, No. 21, November 20, 1995, p. 3314-3116

  When a magnetic recording medium is manufactured by using the nanoimprint method, in order to reduce the magnetic recording pattern and achieve a high recording density, the nanoimprint mold is required to form an increasingly fine pattern. When a fine pattern is formed, the wear of the mold progresses quickly and the frequency of breakage tends to increase. Furthermore, since a resin replica mold has a shorter life than a metal mold, it is necessary to secure a large number of replica molds when using a resin mold. Therefore, it is required to manufacture a replica mold in large quantities with high productivity.

By the way, the material for transferring the concave / convex pattern of the master mold is required to have curability, high flexibility and filling property, and uniform thickness. As a method of satisfying the requirement, for example, a method of printing a gel-like curable resin on a base film and pressing a master mold using the printed film as a transfer material is conceivable.
In order to keep the printed film in a film with a uniform film thickness, a certain degree of viscosity is required for the resin to be printed. However, if the viscosity of the curable resin is increased, the uneven pattern can be filled during transfer with the master mold Therefore, the transfer accuracy tends to decrease.
Further, a method is conceivable in which a dam is provided in advance on the surface of the base film, a liquid curable resin is poured into the dam, and a master mold is stamped on the obtained curable resin layer. However, this method requires a large manufacturing facility, is low in productivity, and is difficult to obtain a thin layer.
In addition, a method of forming a thin film of a curable resin on a base film by spin coating and pressing the master mold using the thin film as a transfer material is also conceivable. There is a tendency.
Therefore, in these methods, productivity cannot be increased, and the accuracy of transferring the concavo-convex pattern may be lowered. Therefore, when the magnetic recording medium is manufactured using the nanoimprint method, the recording density of the magnetic recording medium is lowered and the productivity may be lowered.
The present invention has been made in view of such problems, and an object of the present invention is to provide a method of manufacturing a magnetic recording medium capable of manufacturing a magnetic recording medium capable of realizing a high recording density with high productivity at low cost.

The inventor of the present application has studied to solve the above problems, and as a result, a curable resin material having a low viscosity is sandwiched between a pair of substrates facing each other, and the periphery of the curable resin material is a cured product of the curable resin material. It has been found that the above problem can be solved by using the enclosed laminate for manufacturing a mold used for manufacturing a magnetic recording medium, and the present invention has been completed.
That is, the present invention is as follows.
[1] A step of forming a magnetic layer on at least one surface of a substrate, a step of forming a resist film on the surface of the magnetic layer, a resin mold having a concavo-convex pattern is pressed against the resist film, and the concavo-convex pattern of the mold is resist film Manufacturing a magnetic recording medium having a magnetically separated magnetic recording pattern, including a step of transferring to a magnetic layer, a step of peeling a mold from a resist film, and a step of forming a magnetic recording pattern on a magnetic layer using the transferred concavo-convex pattern A way to
The mold is
A step of sandwiching a liquid or gel-like curable resin material between a pair of substrates facing each other and curing only the peripheral portion of the curable resin material to obtain a laminate,
Peeling one of the substrates from the laminate to expose a layer of the curable resin material,
A step of pressing a master mold having a concavo-convex pattern onto the layer of the curable resin material that is exposed;
A step of curing the layer of the curable resin material while pressing the master mold to obtain a resin mold;
A method of manufacturing a magnetic recording medium, wherein the method is manufactured through a process of peeling a resin mold from a master mold.
[2] The method for producing a magnetic recording medium according to [1], wherein the viscosity of the liquid or gel curable resin material is 10 Pa · s or less.
[3] The curable resin material is a resin material having one or more reactive groups selected from the group consisting of a (meth) acryl group, an oxetanyl group, a cyclohexene oxide group, and a vinyl ether group [1] Or the manufacturing method of the magnetic-recording medium as described in [2].
[4] The curable resin material is a radiation curable resin material that is curable with respect to a wavelength within a range of 300 nm to 400 nm, and a cured product of the curable resin material cures the curable resin material by radiation irradiation. The method for producing a magnetic recording medium according to any one of [1] to [3], wherein the magnetic recording medium is a cured product.
[5] The cured resin of the curable resin material has a transmittance of 20% or more in a wavelength range of 300 nm to 400 nm and a tensile elastic modulus at a temperature of 25 ° C. of 1.3 GPa or more. The method for producing a magnetic recording medium according to any one of [1] to [4].
[6] Any of [1] to [5], wherein the resist film is irradiated with radiation having a wavelength in the range of 300 nm to 400 nm in the step of transferring the uneven pattern of the mold to the resist film. A method for producing a magnetic recording medium according to claim 1.

  According to the method for manufacturing a magnetic recording medium of the present invention, a magnetic recording medium capable of realizing a high recording density can be manufactured with high productivity and at low cost.

  The method of manufacturing a magnetic recording medium of the present invention includes a step of forming a magnetic layer on one side of a substrate, a step of forming a resist film on the surface of the magnetic layer, pressing a resin mold having a concavo-convex pattern against the resist film, Magnetically separated magnetically having a step of transferring the concave / convex pattern of the mold to a resist film, a step of peeling the mold from the resist film, and a step of forming a magnetic recording pattern on the magnetic layer using the transferred concave / convex pattern A method having a recording pattern.

(Mold production method)
The mold in the present invention is obtained by the following steps.
That is, a step of sandwiching a liquid or gel curable resin material between a pair of substrates facing each other and curing a peripheral portion of the curable resin material to obtain a laminate, and peeling one substrate from the laminate A step of pressing a master mold having a concavo-convex pattern onto the layer of the curable resin material, a step of obtaining a resin mold by curing the layer of the curable resin material while pressing the master mold, a master mold The mold is obtained by removing the resin mold from the mold.

One embodiment example of the step of obtaining a laminate will be described.
As shown in FIG. 1, the laminated body in this embodiment includes a pair of long bases 11 and 12 facing each other, a layer 13 of a curable resin material sandwiched between the pair of bases 11 and 12, and The first flow deterring bodies 14 and 14 are sandwiched between the pair of bases 11 and 12 and extend in the length direction. Further, the layer 13 of the curable resin material is enclosed by the pair of base bodies 11 and 12 and the first flow deterrent bodies 14 and 14.

  In the present embodiment in which the bases 11 and 12 are long, the thickness of the layer 13 of the curable resin material sandwiched between them may be non-uniform in the length direction of the film. Therefore, in this embodiment, as shown in FIG. 2, linear second flow restrainers 15, 15 are provided at regular intervals along the width direction. If the second flow restrainers 15 and 15 are provided in the width direction in this way, the curable resin material is less likely to move in the length direction, and thus the thickness of the layer 13 of the curable resin material is long. It is possible to prevent the direction from becoming uneven.

The laminate 10 is produced as follows.
First, a curable resin material diluted with a solvent is applied to one substrate 11 and dried to remove the solvent, and then the other substrate 12 is mounted.
Next, the peripheral portion of the curable resin material sandwiched between the substrates 11 and 12 is cured to form the first flow restraining body 14. The method for forming the first flow suppressing body 14 is not particularly limited, and can be appropriately selected according to the properties of the curable resin material. For example, after the other substrate 12 is placed, it is not wound on a roll. The method of hardening only the both ends of the width direction with an ultraviolet irradiation machine is mentioned. According to this method, continuous production is efficient, and productivity can be further increased.
When the viscosity of the layer 13 of the curable resin material is low and only the both ends are cured, the degree of curing and the bonding property to the substrates 11 and 12 are insufficient, and a plurality of ultraviolet irradiators are used. It is preferable to irradiate the curable resin material with ultraviolet rays.

Next, the second flow suppressing body 15 is formed by irradiating ultraviolet rays along the width direction. If the 2nd flow suppression body 15 is formed, the thickness of encapsulated curable resin material can be made more uniform.
As a method of forming the second flow suppressing body 15, for example, a method of irradiating ultraviolet rays at regular intervals by controlling on / off of the ultraviolet irradiation device with a timer, or using a shutter along the width direction at regular intervals. Examples include a method of irradiating with ultraviolet rays.
As described above, the first flow deterrent body 14 and the second flow deterrent body 15 are formed to encapsulate the layer 13 of the curable resin material. Then, it rolls up with a roll and the roll of the laminated body 10 is obtained.

Since the base bodies 11 and 12 in this embodiment are long, the master mold can be stamped continuously.
There is no restriction | limiting in particular as the length of the elongate base | substrates 11 and 12, For example, they are 10m-20,000m.

  In the present embodiment in which the bases 11 and 12 are long, the thickness of the layer 13 of the curable resin material sandwiched between them may be non-uniform in the length direction of the film. Therefore, in this embodiment, as shown in FIG. 2, linear second flow restrainers 15, 15 are provided at regular intervals along the width direction. If the second flow restrainers 15, 15 are provided in the width direction in this way, the curable resin material is less likely to move in the length direction, so the thickness of the layer 13 of the curable resin material is in the length direction. Non-uniformity can be prevented.

The material for the substrates 11 and 12 is not particularly limited and may be appropriately selected depending on the intended purpose. However, when a photocurable resin is used as the curable resin material, it transmits radiation for curing. Is preferred. Furthermore, in order to make the thickness of the layer 13 of the curable resin material constant, it is more preferable that the surface smoothness is good.
Specific materials for the substrates 11 and 12 include transparent synthetic resins such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, cellulose triacetate, cellulose diacetate, poly (meth) acrylic acid alkyl ester, and poly (meta ) Acrylic ester copolymer, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polystyrene, cellophane, polyvinylidene chloride copolymer, polyamide, polyimide, vinyl chloride / vinyl acetate copolymer, polytetrafluoroethylene, polytrifluoroethylene And various plastic films such as cellulose film and nylon film. Among these, polyethylene terephthalate is preferable. These materials may be used alone or in combination of two or more.

Moreover, it is preferable that at least one of the base | substrates 11 and 12 is a material which can peel the hardened | cured material of curable resin material.
When a replica mold is manufactured using the laminate 10, at least one of the bases 11 and 12 is peeled off, so that at least one of the bases 11 and 12 is made of a material that can peel a cured product of the curable resin material. In this case, workability at the time of peeling the substrates 11 and 12 is improved.
However, if the peelability of the substrates 11 and 12 is too high, the curable resin material sandwiched between the substrates 11 and 12 may leak out. Therefore, the peelability of the bases 11 and 12 is preferably such that the curable resin material does not leak out.
The substrates 11 and 12 are a thermoplastic resin or a thermosetting resin having a glass transition temperature (Tg) higher than the heating temperature at the time of compression molding in order to prevent deformation due to heating at the time of compression molding. It is preferable.

A separate film, which is a peelable film, may be provided on the curable resin material layer 13 side of the substrates 11 and 12. As described above, the bases 11 and 12 are preferably made of a material capable of peeling a cured product of the curable resin material. On the other hand, the base 11 serving as a base film has a layer 13 of the curable resin material. In order to keep the film flat, high rigidity is required, and the base 12 that becomes the cover film is required to have high flexibility in terms of ease of peeling. In response to this requirement, if a separate film is provided on the curable resin material layer 13 side of the bases 11 and 12 to ensure the peelability of the curable resin material from the cured product, the bases 11 and 12 have rigidity or flexibility. You can choose a higher one. Therefore, the request can be easily satisfied.
The separate film is selected depending on the bondability with the substrates 11 and 12, and examples thereof include paper, paper laminated with polyethylene and polypropylene, and among these, polyethylene film and polypropylene film are preferable.

There is no restriction | limiting in particular as thickness of a separate film, Although it can select suitably according to the objective, 5 micrometers-100 micrometers are preferable, 8 micrometers-50 micrometers are more preferable, and 10-30 micrometers are especially preferable.
In the case of using a separate film, it is preferable that the cured product of the curable resin material and the separated film are more easily separated from the cured product of the curable resin material and the bases 11 and 12, and the separate film and the curable resin material are used. More preferably, the adhesive strength between layers of the cured product is smaller than the adhesive strength between the other layers.

  Examples of the combination of the substrates 11 and 12 and the separate film (hereinafter referred to as the combination of the substrate and the separate film) include, for example, polyethylene terephthalate / polypropylene, polyethylene terephthalate / polyethylene, polyvinyl chloride / cellophane, polyimide / polypropylene, polyethylene terephthalate. / Polyethylene terephthalate.

Moreover, the surface treatment for adjusting adhesive force may be given to at least one of the base | substrates 11 and 12 and a separate film. Examples of the surface treatment include coating of an undercoat layer, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, high frequency irradiation treatment, glow discharge irradiation treatment, active plasma irradiation treatment, and laser beam irradiation treatment.
Among these, as a method of coating the undercoat layer, a coating liquid containing a polymer such as polyorganosiloxane, fluorinated polyolefin, polyfluoroethylene, polyvinyl alcohol, or the like was applied to the surface of the substrate 11, 12 or a separate film. Then, the method of drying at 30 degreeC-150 degreeC (especially 50 degreeC-120 degreeC) for 1 minute-30 minutes etc. are mentioned.

  The coefficient of static friction between the substrates 11 and 12 and the separate film is preferably 0.3 to 1.4, and more preferably 0.5 to 1.2. If the coefficient of static friction is less than 0.3, it slips too much, so when the laminate is rolled, winding deviation may occur, and if it exceeds 1.4, it will be difficult to wind in a roll. There is.

  There is no restriction | limiting in particular as thickness of the base | substrates 11 and 12, Although it can select suitably according to the objective, 2 micrometers-300 micrometers are preferable, 5 micrometers-200 micrometers are more preferable, 8 micrometers-100 micrometers are especially preferable.

The curable resin material is a liquid or gel-like fluid material. Especially, since the resin mold can be manufactured with higher accuracy, the viscosity thereof is preferably 10 Pa · s or less. Here, the viscosity is a value measured using, for example, a viscometer (manufactured by Brookfield, trade name “DV-EVISCOMETER”) in an environment of 25 ° C.
The curable resin material is preferably a resin material having one or more reactive groups selected from the group consisting of a (meth) acryl group, an oxetanyl group, a cyclohexene oxide group, and a vinyl ether group because of excellent curability.
Further, as the curable resin material, a radiation curable resin is used when the laminate 10 is used for the optical nanoimprint method, and a thermoplastic resin or a thermosetting resin is used when the thermal nanoimprint method is used.
In particular, a radiation curable resin material is more preferable as the curable resin material. According to the radiation curable resin material, it can be easily cured in a short time by light irradiation, so that the process of manufacturing the replica mold from the master mold can be performed easily and in a short time.

The radiation curable resin material contains a resin that is curable with respect to a wavelength within a range of 300 nm to 400 nm, and the cured product after curing has a transmittance of 20% or more at a wavelength within a range of 300 nm to 400 nm. It is preferable that the tensile elastic modulus at 25 ° C. is 1.3 GPa or more. When such a radiation curable resin is used, the curability of the curable resin material sufficiently transmits light, so that the photo nanoimprint method can be applied to the nanoimprint process. Moreover, if the tensile elasticity modulus of the hardened | cured material of curable resin material is 1.3 GPa or more, the resin-made mold of the physical property suitable for the nanoimprint method is obtained.
Further, since such a radiation curable resin material has a low shrinkage rate at the time of photocuring and a high mold releasability with respect to the master mold, a resin having a fine concavo-convex pattern can be obtained by manufacturing a replica mold using this resin material. A mold can be manufactured with a low defect rate.
The wavelength transmittance is measured using, for example, a spectrophotometer (trade name “V-650” manufactured by JASCO Corporation). In the measurement, the thickness of the cured film of the sample is 20 μm, and the measurement temperature is room temperature. Further, the tensile elastic modulus is derived in accordance with JIS K7120. That is, it is derived by attaching a cured film for evaluation to a rheometer (for example, product name “RT-3010D-CW” manufactured by FUDOH) with a chuck width of 50 mm, stretching at 25 ° C., and determining the displacement up to the breaking point. To do.

  As a radiation curable resin material having curability with respect to ultraviolet rays within a range of 300 nm to 400 nm, one containing an acrylic monomer (A), a photopolymerization initiator (B) and a release agent (C) is used. preferable.

The acrylic monomer (A) is not particularly limited and can be appropriately selected depending on the purpose. For example, (meth) acrylic acid esters and (meth) acrylic acid amides are used. In the present specification, (meth) acrylic acid is a general term for acrylic acid and methacrylic acid.
Specific examples of (meth) acrylic acid esters include the following compounds.
Phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) ) Acrylate, tetrahydrofurfuryl (meth) acrylate, allyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N -Mono (meth) acrylates such as dimethylaminoethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate.
1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) Di (meth) acrylates such as acrylate, polyoxyethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate.
Tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate and pentaaerythritol tri (meth) acrylate.
Other (meth) acrylates such as dipentaerythritol hexa (meth) acrylate.
Examples of the (meth) acrylamides include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N- n-butylacryl (meth) amide, Nt-butyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N- (2-methoxyethyl) (meth) acrylamide, N, N-dimethyl (meth) acrylamide, Examples thereof include N, N-diethyl (meth) acrylamide, N-phenyl (meth) acrylamide, N-benzyl (meth) acrylamide, (meth) acryloylmorpholine, diacetone acrylamide and the like. Specific product names include Beam Set 371 (Arakawa Chemical Industries).
These acrylic monomers may be used individually by 1 type, and may use 2 or more types together.

  The content of the acrylic monomer in the radiation curable resin material is preferably 85 to 98% by mass, more preferably 87.5 to 96% by mass, and particularly preferably 90 to 94% by mass. If the acrylic monomer content is 85% by mass or more, sufficiently good physical properties can be obtained when the cured material is molded and used, and if it is 98% by mass or less, a polymerization initiator or a mold release agent is obtained. By mixing with an agent or the like, the physical properties of the cured material can be easily adjusted.

Examples of the photopolymerization initiator (B) include acetophenone photopolymerization initiators, benzoin photopolymerization initiators, benzophenone photopolymerization initiators, thioxanthone photopolymerization initiators, and thioxanthone photopolymerization initiators. .
Acetophenone-based photopolymerization initiator: acetophenone, p- (tert-butyl) 1 ′, 1 ′, 1′-trichloroacetophenone, chloroacetophenone, 2 ′, 2′-diethoxyacetophenone, hydroxyacetophenone, 2,2-dimethoxy- 2'-phenylacetophenone, 2-aminoacetophenone, dialkylaminoacetophenone and the like.
Benzoin photopolymerization initiators: benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-2-methylpropane -1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, benzyldimethyl ketal and the like.
Benzophenone-based photopolymerization initiators: benzophenone, benzoylbenzoic acid, benzoylmethyl benzoate, methyl-o-benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, hydroxypropylbenzophenone, acrylic benzophenone, 4,4'-bis (dimethylamino) Benzophenone etc.
Thioxanthone photopolymerization initiators: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, diethylthioxanthone, dimethylthioxanthone, and the like.
Other photopolymerization initiators: α-acyloxime ester, benzyl- (o-ethoxycarbonyl) -α-monooxime, acylphosphine oxide, glyoxyester, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, tetramethylthiuram Sulfide, azobisisobutyronitrile, benzoyl peroxide, dialkyl peroxide, tert-butyl peroxypivalate and the like.

  The content of the polymerization initiator in the radiation curable resin material is preferably 0.001 to 10 parts by mass, and 0.01 to 10 parts by mass with respect to 100 parts by mass of the acrylic monomer. More preferred is 0.1 to 5 parts by mass. If the content of the polymerization initiator is 0.001 part by mass or more, the acrylic monomer can be polymerized in a short time, and if it is 10 parts by mass or less, the residue of the polymerization initiator hardly remains in the cured product.

As the release agent (C), it is preferable to include a fluorine-containing surfactant since a cured product having better release properties can be obtained. Furthermore, a fluorine-containing surfactant having a fluorine content of 10 to 70% by mass is more preferable, and a fluorine-containing surfactant having a fluorine content of 10 to 40% by mass is particularly preferable. The fluorine-containing surfactant may be water-soluble or oil-soluble.
As the fluorine-containing surfactant, any of an anionic fluorine-containing surfactant, a cationic fluorine-containing surfactant, an amphoteric fluorine-containing surfactant, and a nonionic fluorine-containing surfactant may be used. Among these, nonionic fluorine-containing surfactants are particularly preferable because they have good compatibility in the curable resin material and good dispersibility in the cured product.

As the anionic fluorine-containing surfactant, a polyfluoroalkyl carboxylate, a polyfluoroalkyl phosphate, or a polyfluoroalkyl sulfonate is preferable. Specific examples of the cationic surfactant include Surflon S-111 (trade name, manufactured by Seimi Chemical Co., Ltd.), Florard FC-143 (trade name, manufactured by 3M Co., Ltd.), MegaFuck F-120, MegaFak R-30 ( Trade name, manufactured by DIC Corporation).
As the cationic fluorine-containing surfactant, a trimethylammonium salt of polyfluoroalkylcarboxylic acid or a trimethylammonium salt of polyfluoroalkylsulfonic acid amide is preferable. Specific examples of the cationic surfactant include Surflon S-121 (trade name, manufactured by Seimi Chemical Co., Ltd.), Florard FC-134 (trade name, manufactured by 3M Co., Ltd.), Megafac F-150 (trade name, manufactured by DIC Corporation). ) And the like.
As the amphoteric fluorine-containing surfactant, polyfluoroalkyl betaine is preferable. Specific examples of amphoteric surfactants include Surflon S-132 (trade name, manufactured by Seimi Chemical Co., Ltd.), Florard FX-172 (trade name, manufactured by 3M), MegaFuck F-120 (trade name, manufactured by DIC). Etc.
As the nonionic fluorine-containing surfactant, polyfluoroalkylamine oxide or polyfluoroalkyl / alkylene oxide adduct is preferable. Specific examples of the nonionic surfactant include Surflon S-145 (trade name, manufactured by Seimi Chemical Co., Ltd.), Surflon S-393 (trade name, manufactured by Seimi Chemical Co., Ltd.), and Surflon KH-20 (trade name, Seimi Chemical Co., Ltd.). ), Surflon KH-40 (trade name, manufactured by Seimi Chemical Co., Ltd.), Florard FC-170 (trade name, manufactured by 3M), Florado FC-430 (trade name, manufactured by 3M), MegaFuck F-141 (product) Name, manufactured by DIC Corporation).

  The content of the fluorine-containing surfactant in the radiation curable resin material is preferably 0.01 to 10% by mass, and 0.1 to 5% by mass when the entire radiation curable resin material is 100% by mass. More preferred. If the content of the fluorine-containing surfactant is 0.01% by mass or more, a cured product excellent in releasability can be reliably formed, and if it is 10% by mass or less, a radiation curable resin material is easily prepared. it can.

  When a thermosetting resin is used as the curable resin material, the thermosetting resin has a glass transition temperature (Tg) higher than the heating temperature at the time of compression molding from the viewpoint of compatibility with the thermal nanoimprint method. A thermosetting resin is preferable.

  The thickness of the layer 13 of the curable resin material is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 1 μm to 50 μm, more preferably 3 μm to 25 μm, and particularly preferably 5 μm to 15 μm.

  The first flow deterrent body 14 and the second flow deterrent body 15 are made of a cured product obtained by curing the curable resin material. It is preferable that the width | variety of 1st flow suppression body 14 itself and 2nd flow suppression body 15 itself is 1 mm-20 mm. If the width of the first flow deterrent body 14 itself and the second flow deterrent body 15 itself is 1 mm or more, the curable resin material can be reliably sealed, and if the width is 20 mm or less, the uncured curable resin material A sufficient area can be secured.

In the laminated body described above, the curable resin material layer 13 is enclosed by the bases 11 and 12, the first flow deterrent body 14, and the second flow deterrent body 15, thereby preventing the curable resin material from flowing out. Thus, the layer 13 of the curable resin material can be made thin and uniform. In particular, since the first flow suppressing body 14 is obtained by curing the curable resin material itself, the thickness thereof is uniform over the entire layer 13 of the curable resin material. Therefore, when the master mold is pressed, the concavo-convex pattern can be transferred with high accuracy to obtain a resin replica mold.
In addition, if such a laminate 10 is used, a layer 13 of a curable resin material that is a raw material for manufacturing a replica mold can be easily and continuously supplied to a stamper device without using a large facility. A resin replica mold having a concavo-convex pattern can be produced in large quantities with high productivity.

  The laminated body is not limited to the above-described one. For example, as shown in FIG. 3, the layer 13 of the curable resin material is formed into a circular shape and the other portion 16 is cured to form a flow suppressing body. There may be.

An embodiment of a method for producing a resin replica mold using the above laminate and master mold will be described.
4 to 6 show an apparatus for producing a resin mold using a master mold.
The resin mold manufacturing apparatus 100 includes an upper mold set 110 supported by a first mounting board 111 and a lower mold set 120 supported by a second mounting board 121. Here, the first mounting plate 111 is supported by a vertically moving actuator device such as a hydraulic cylinder (not shown) so as to be movable up and down, and the second mounting plate 121 is installed on a base (not shown). It is fixed.

A disc-shaped cutter set member 112 is provided above the first mounting plate 111 so as to be movable up and down supported by an actuator device for vertical movement such as a hydraulic cylinder (not shown). A cylindrical outer cutter 114 is provided on the bottom outer peripheral side of the cutter set member 112, and a round bar-shaped inner cutter 115 is provided in the center of the bottom of the cutter set member 112. A cutter member 116 is composed of the inner cutter 115 and the inner cutter 115. Further, a ring-shaped outer cutter blade 117 is formed downward on the tip end side of the outer cutter portion 114, and an inner cutter blade 118 is formed on the tip end side of the inner cutter portion 115.
The outer cutter 114 extends to the lower side of the first mounting plate 111 through a through hole 111a formed in the outer periphery of the first mounting plate 111, and the inner cutter 115 is a first attachment. The outer cutter part 114 is extended to the lower side of the first mounting board 111 through a through hole 111b formed in the center of the board 111, and the cutter set member 112 is moved up and down relative to the first mounting board 111. And the inner cutter 115 are configured to move up and down.
The cross section of the outer cutter blade 117 is formed in a triangular shape, and the cutting edge surface 117a is formed by extending the inner peripheral surface 114a of the cylindrical outer cutter portion 114 as it is, and the outer cutter blade 117 faces outward. It has an inclined outer blade surface 117b. The inner peripheral cutter blade 118 has a cutting blade surface 118a having a shape obtained by extending the outer peripheral surface of the round bar-shaped inner peripheral cutter portion 115 as it is, and an inverted V-shaped cross section formed at the tip of the inner peripheral cutter portion 115. The cutting edge is formed of a mortar-shaped recess 118b.

  A radiation source support mechanism 130 and an irradiation device 140 are provided on the lower side of the first mounting plate 111 and between the outer peripheral cutter portion 114 and the inner peripheral cutter portion 115. It is configured so that ultraviolet light can be irradiated downward from a built-in high-pressure mercury lamp, low-pressure mercury lamp, metal halide lamp, xenon lamp, xenon mercury lamp, ultraviolet LED lamp, or the like. Among these radiation sources, it is particularly preferable to use an ultraviolet LED lamp because heat generation that causes distortion of a molded product is small. Examples of the wavelength of ultraviolet rays used in this case include a range of 300 nm to 400 nm.

  A frame-shaped support member 150 is installed below the irradiation device 140, and a radiation transmitting press base 160 such as a disk-shaped glass disk is provided below the support member 150. The radiation source support member 150, the irradiation device 140, and the radiation transmitting pressure base 160 are integrated with the first mounting plate 111, and the radiation transmitting pressure base 160 moves up and down according to the vertical movement of the first mounting plate 111. Is configured to do.

  On the other hand, a cylindrical inner sliding support member 170 and a cylindrical outer sliding support member 180 having the same height are provided on the second mounting plate 121, and a disc-shaped receiving base is provided therebetween. 190 is slidably fitted up and down, and the cradle 190 is supported by an elastic member 191 such as a spring member provided on the lower side thereof. A donut disk-shaped master mold 20 is installed on the cradle 190 so as to protrude slightly above the sliding support members 170 and 180.

The master mold 20 has an uneven pattern to be transferred on the upper surface side. In this embodiment, since a resin mold for forming a concavo-convex pattern on the surface of a discrete track magnetic recording medium is to be manufactured, a thin film formed on the surface of the discrete track magnetic recording medium is formed on the surface of the master mold 20. The uneven pattern is formed.
Further, a concave portion 171 into which the rod-shaped inner peripheral cutter blade 118 can be inserted is formed at the center of the inner support member 170.

In order to manufacture a resin mold with the apparatus having the configuration shown in FIG. 4, the film-like laminate 10 serving as a base of the target resin mold is prepared.
One substrate 12 which is a cover film of the laminate 10 is peeled to expose the layer 13 (see FIG. 1) of the curable resin material (hereinafter, the substrate 12 is peeled off is referred to as a laminate 10a). As shown in FIG. 7, the laminate 10 a is sandwiched between the master mold 20 and the radiation transmitting press substrate 160, the first mounting plate 111 is lowered, and the laminate 10 a is defined on the surface of the master mold 20 through the radiation transmitting press substrate 160. Press with pressure of. The master mold 20 is a material that can be precisely processed, such as a Ni alloy, and a metal plate made of a material that can accurately form fine irregularities with the current forming technology can be applied.
By this operation, the fine concavo-convex pattern which is the reverse pattern of the fine concavo-convex formed on the surface of the master mold 20 is transferred to the layer 13 of the curable resin material of the laminate 10a (the above process is referred to as a transfer process).

Next, with the laminated body 10a pressed against the surface of the master mold 20, the irradiation device 140 irradiates ultraviolet radiation to cure the curable resin material (the above process is referred to as a curing process).
Before or after the curing or during the curing, as shown in FIG. 8, the cutter set member 112 is lowered to lower the outer cutter 114 and the inner cutter 115, and the outer cutter blade 117 and the inner cutter. The disc-shaped resin mold 30 is punched from the laminated body 10a by the blade 118 (the above process is referred to as a punching process).
At the time of this punching, the outer peripheral cutter blade 117 punches the laminate 10a while sliding along the outer peripheral extension surface of the cylindrical outer sliding support member 180, and the inner peripheral cutter blade 118 Since the laminated body 10a is punched while sliding along the inner side, the laminated body 10a can be punched at an accurate position, and a donut disk-shaped mold 30 having an intended inner diameter and outer diameter can be obtained. .

Further, as shown in FIG. 8, the central portion 10 b of the laminate 10 a punched out by the inner cutter blade 118 is formed on the inner sliding support member 170 in a portion excluding the portion that has been punched out of the laminate 10 a to become the mold 30. The outer peripheral portion 10c of the laminated body 10a discharged to the center concave portion 171 side and punched out by the outer peripheral cutter blade 117 is discharged to the outer peripheral side of the outer sliding support member 180. Here, since the inner diameter of the concave portion 171 of the sliding support member 170 is substantially equal to the outer diameter of the inner cutter blade 118, when the laminated body 10a is punched, the laminated body 10a is formed along the inner peripheral edge of the concave portion 171. Can be punched by the inner cutter 118 at an accurate position without difficulty, and the punching accuracy can be improved. Further, since the outer diameter of the outer sliding support member 180 is substantially equal to the inner diameter of the outer cutter blade 117, the laminate 10a is formed along the outer peripheral edge of the outer sliding support member 180 when punching the laminate 10a. Can be punched by the outer cutter blade 117 at an accurate position without difficulty, and the punching accuracy can be improved. Therefore, the laminated body 10a can be punched into a desired donut disk shape in which the shape and position accuracy of the inner circumference circle and the shape and position accuracy of the outer circumference circle are both high.
In this manufacturing method, when the resin mold has a long shape in which the same pattern is continuously provided, punching with the cutter blade is performed only on the inner circumference, and the outer circumference is not punched.

  As shown in FIG. 8, after punching the laminated body 10a, when the first mounting plate 111 and the cutter set member 112 are raised as shown in FIG. 9, the gap between the outer cutter blade 117 and the inner cutter blade 118 is increased. Since the mold 30 is lifted in the sandwiched state, as shown in FIG. 10, the cutter set member 112 is raised with respect to the first mounting plate 111 to remove the outer cutter blade 117 and the inner cutter blade 118 from the mold 30. Further, the mold 30 can be taken out using a peeling means such as a take-out rod 40 having a bent portion 41 at the tip. At this time, the outer cutter blade 117 and the inner cutter blade 118 have already been removed from the mold 30, and the mold 30 is in close contact with only the radiation transmitting press substrate 160, so that the mold 30 can be easily removed by the extraction rod 31. Can be peeled off.

  After the mold 30 is removed from the radiation transmitting press substrate 160, a new laminate 10a is disposed between the radiation transmitting press substrate 160 and the master mold 20 as shown in FIG. The mold 30 is obtained by performing an irradiation process and a punching process. The mold 30 can be mass-produced by repeating the above operation.

(Method of manufacturing magnetic recording medium)
The method for manufacturing a magnetic recording medium of the present invention is applied to, for example, manufacturing a discrete track type magnetic recording medium or a patterned medium. An example of this type of magnetic recording medium is one in which a magnetic layer or a protective layer is formed on the surface of a nonmagnetic substrate.
For example, the magnetic layer formed on the surface of the nonmagnetic substrate as described above may be an in-plane magnetic layer or a perpendicular magnetic layer. These magnetic layers are preferably formed from an alloy mainly containing Co as a main component.

For example, as the magnetic layer for the in-plane magnetic recording medium, a laminated structure composed of a nonmagnetic CrMo underlayer and a ferromagnetic CoCrPtTa magnetic layer can be used.
Examples of magnetic layers for perpendicular magnetic recording media include soft magnetic FeCo alloys (FeCoB, FeCoSiB, FeCoZr, FeCoZrB, FeCoZrBCu, etc.), FeTa alloys (FeTaN, FeTaC, etc.), Co alloys (CoTaZr, CoZrNB, CoB, etc.), etc. A backing layer made of, an orientation control film such as Pt, Pd, NiCr, NiFeCr, an intermediate film such as Ru, if necessary, and a magnetic layer made of 60Co-15Cr-15Pt alloy or 70Co-5Cr-15Pt-10SiO ₂ alloy. Stacked ones can be used.

  The thickness of the magnetic layer is 3 nm to 20 nm, preferably 5 nm to 15 nm. The magnetic layer may be formed so as to obtain sufficient head input / output according to the type of magnetic alloy used and the laminated structure. The film thickness of the magnetic layer needs to be greater than a certain level in order to obtain a certain level of output during playback. On the other hand, each parameter indicating recording / reproduction characteristics deteriorates as the output increases. It is necessary to set the film thickness. Usually, the magnetic layer is formed as a thin film by sputtering.

In this method of manufacturing a magnetic recording medium, a magnetic recording pattern magnetically separated is formed on the magnetic layer. Prior to the step, a step of forming a resist film on the surface of the magnetic layer, a resin made with a concavo-convex pattern A mask layer is formed by pressing the mold against the resist film and transferring the uneven pattern of the mold to the resist film and peeling the mold from the resist film.
Hereinafter, an embodiment of a method for manufacturing a magnetic recording medium of the present invention using the above-described mold will be described. However, the manufacturing method of the present invention is not limited to the following method.

  The method of manufacturing the magnetic recording medium of this example includes, for example, a process A (see FIG. 12) for forming at least the magnetic layer 220 on the nonmagnetic substrate 210, and a process B (see FIG. 12) for forming the mask layer 230 on the magnetic layer 220. 13), a process C (see FIG. 14) for forming a resist film 240 on the mask layer 230, and a process D (process for transferring a negative pattern of a magnetic recording pattern to the resist film 240 using a resin mold 250. The arrow in D indicates the movement of the mold 250. Therefore, the downward arrow indicates the step of pressing the resin mold 250 against the resist film 240, and the upward arrow indicates the step of peeling the mold 250 from the substrate 210) (FIG. 15). See step E), removing the mask layer 230 in the portion corresponding to the negative pattern of the magnetic recording pattern (recessed portion in the figure of the step D). In the case where the resist film 240 remains, the resist film 240 and the mask layer 230 are removed (see FIG. 16), and the surface layer portion of the magnetic layer 220 is partially ion milled from the resist film 240 side surface F (reference numeral 270). Indicates a portion where ion milling is partially performed in the magnetic layer, and symbol d indicates the depth of ion milling in the magnetic layer) (see FIG. 17). Step G for modifying the magnetic properties of the magnetic layer 220 by exposure to the reactive ions 270 (reference numeral 280 indicates a portion where the magnetic properties have been modified in the magnetic layer) (see FIG. 18), the resist film 240 and the mask layer 230. Step H (see FIG. 19), irradiating the magnetic layer 220 with an inert gas, and covering the surface of the magnetic layer 220 with a protective film 290 (see FIG. 20). It is the law.

The mask layer 230 formed on the magnetic layer 220 in the step B in this manufacturing method is Ta, W, Ta nitride, W nitride, Si, SiO ₂ , Ta ₂ O ₅ , Re, Mo, Ti, V , Nb, Sn, Ga, Ge, As, and Ni are preferably formed of a material containing one or more selected from the group consisting of Nb, Sn, Ga, Ge, As, and Ni. By using such a material, the shielding property of the mask layer 230 against the milling ions 260 can be improved, and the magnetic recording pattern formation characteristics by the mask layer 230 can be improved. Furthermore, since these materials are easy to dry-etch using a reactive gas, residue can be reduced and contamination of the magnetic recording medium surface can be reduced in Step H.
In this manufacturing method, among these substances, As, Ge, Sn, and Ga are preferably used as the mask layer 230, more preferably Ni, Ti, V, and Nb are used, and Mo, Ta, and W are used. Most preferably, it is used. The thickness of the mask layer 230 is generally preferably in the range of 1 nm to 20 nm.

  Next, in step C, a resist is applied on the magnetic layer 220 through the mask layer 230 to form a resist film 240. As the resist, those having good transfer characteristics by a resin mold can be used, but it is preferable to use a resin that is curable with respect to radiation. For example, novolak resins, acrylic esters, alicyclic epoxies, etc. It is preferable to use an ultraviolet curable resin such as

  Next, in step D, the resin mold 250 on which the concavo-convex pattern is formed is pressed against the resist film 240, the concavo-convex pattern of the mold 250 is transferred to the resist film 240, and then the mold 250 is peeled off from the substrate 210. Here, the pressure for pressing the resin mold 250 against the resist film 240 can be set to 60 MPa or less as an example. This pressure can be calculated as compressive force / mold area, in other words, by dividing the weight detected by the press device by the mold area. Further, the resin mold 250 can be formed in an arbitrary shape. For example, the resin mold 250 can be formed into a disk shape in which both the outer peripheral portion and the inner peripheral portion are punched. In this manufacturing method, as described above, as shown in FIG. It is preferable from the productivity of the magnetic recording medium to use a long resin mold 250 in which the same pattern is continuously provided as shown.

Further, as shown in FIG. 21, an opening 10d is provided in a long mold 250, the opening 10d is aligned with the opening of the substrate 210, alignment is performed, and the mold 250 is attached to a radiation transmissive jig. Thus, the magnetic recording medium can be manufactured with high productivity by being pressed against the substrate 210 and irradiating with radiation for curing the resist film 240 from the jig side.
In the film shown in FIG. 21, since the same pattern mold is continuously provided, each process can be performed continuously, and both surfaces of the magnetic recording medium substrate can be easily processed simultaneously. Is possible.

  In this manufacturing method, it is preferable that the thickness of the concave portion of the resist film 240 after transferring the negative pattern of the magnetic recording pattern to the resist film 240 shown in Steps C and D is in the range of 0 to 10 nm. By setting the thickness of the concave portion of the resist film 240 within this range, the sagging of the edge portion of the mask layer 230 is eliminated in the etching process of the mask layer 230 shown in the step E, and the mask layer 230 shields against the milling ions 260. In addition, the magnetic recording pattern formation characteristics by the mask layer 230 can be improved. The thickness of the resist is generally about 10 nm to 100 nm.

As a material used for the resist film 240 in Steps C and D, it is preferable to use a radiation curable material. However, the resist may be irradiated with radiation at the time of transferring the pattern to the resist film 240 using the mold 250. The resist film 240 may be irradiated after the pattern transfer process. By using such a manufacturing method, the uneven pattern of the mold 250 can be accurately transferred to the resist film 240. In the etching process of the mask layer 230 shown in the process E, the edge portion of the mask layer 230 is transferred. The sagging of the mask layer 230 can be eliminated, the shielding property against the implanted ions of the mask layer 230 can be improved, and the magnetic recording pattern formation characteristics by the mask layer 230 can be improved. The radiation in the present invention is a broad concept electromagnetic wave such as heat rays, visible radiation, ultraviolet rays, X-rays, gamma rays and the like. In addition, the material curable by radiation is, for example, a thermosetting resin for heat rays and an ultraviolet curable resin for ultraviolet rays.
The radiation for curing the resist film 240 in the step of transferring the concave / convex pattern of the mold to the resist film is general-purpose, and ultraviolet rays having a wavelength in the range of 300 nm to 400 nm are preferable in that the productivity can be further increased.

In this manufacturing method, in particular, in the process of transferring the pattern to the resist film 240 using the mold 250, the resist film 240 is pressed with the mold 250 in a state where the fluidity of the resist film 240 is high. By irradiating the resist film 240 with radiation, the resist film 240 is cured, and then the mold 250 is separated from the resist film 240, whereby the shape of the mold 250 can be transferred to the resist film 240 with high accuracy.
As a method of irradiating the resist film 240 with radiation while the mold 250 is pressed against the resist film 240, in addition to a method of irradiating from the opposite side of the mold 250, a method of irradiating radiation from the substrate 210 side, a side surface of the mold 250 A method of irradiating radiation from a mold material or a method of irradiating radiation by thermal conduction from the substrate 210 using a radiation having high conductivity with respect to a solid like a heat ray can be used.

By such a manufacturing method, the magnetic characteristics of the region between the magnetic tracks (the region separating the magnetic layer 220) is lowered, for example, the coercive force and the residual magnetization are reduced to the limit, thereby eliminating writing blur at the time of magnetic recording. A magnetic recording medium having a surface recording density can be obtained.
In this manufacturing method, as shown in Step F, it is preferable to remove a part of the surface layer of the magnetic layer 220 by ion milling or the like. As in this manufacturing method, it is more effective to remove a part of the surface layer of the magnetic layer 220 and then modify the magnetic properties of the magnetic layer 220 by exposing the surface to reactive plasma or reactive ions. Compared to the case where part of 220 is not removed, the contrast of the magnetic recording pattern becomes clearer and the S / N of the magnetic recording medium is improved. The reason for this is that by removing the surface layer portion of the magnetic layer 220, the surface is cleaned and activated, the reactivity with reactive plasma and reactive ions is increased, and the magnetic layer 220 is It is considered that defects such as vacancies were introduced into the surface layer portion, and reactive ions easily entered the magnetic layer 220 through the defects.
The depth d at which a part of the surface layer of the magnetic layer 220 is removed by ion milling or the like is preferably in the range of 0.1 nm to 15 nm, more preferably in the range of 1 to 10 nm. When the removal depth by ion milling is less than 0.1 nm, the removal effect of the magnetic layer 220 described above does not appear, and when the removal depth is greater than 15 nm, the surface smoothness of the magnetic recording medium decreases, and the magnetic The flying characteristics of the magnetic head when the recording / reproducing apparatus is manufactured tend to deteriorate.

In this manufacturing method, for example, the magnetic characteristics of the magnetic layer 220 are improved by exposing the magnetic layer 220 already formed to reactive plasma or reactive ions in a region where the magnetic recording track and the servo signal pattern portion are magnetically separated. It is formed by quality (decrease in magnetic properties).
Here, as shown in Step G, the magnetically separated magnetic recording pattern is a state in which the magnetic layer 220 is separated by a region 280 demagnetized when the magnetic recording medium is viewed from the surface side. Sure. That is, if the magnetic layer 220 is separated from the surface side, the object of the present invention can be achieved even if the magnetic layer 220 is not separated at the bottom of the magnetic layer 220, and the magnetic recording pattern separated magnetically. Included in the concept. The magnetic recording pattern includes a so-called patterned medium in which the magnetic recording pattern is arranged with a certain regularity for each bit, a medium in which the magnetic recording pattern is arranged in a track shape, and other servo signal patterns. Is included.
Among these, the present manufacturing method is preferably applied to a so-called discrete type magnetic recording medium in which the magnetic recording patterns magnetically separated are magnetic recording tracks and servo signal patterns, from the viewpoint of simplicity in manufacturing.
In the present manufacturing method, the modification of the magnetic properties of the magnetic layer 220 for forming the magnetic recording pattern means that the coercive force, residual magnetization, etc. of the magnetic layer 220 are partially changed in order to pattern the magnetic layer 220. The change means that the coercive force is lowered and the residual magnetization is lowered.
Further, in the present manufacturing method, the magnetic layer 220 is amorphized by exposing the magnetic layer 220 already formed to reactive plasma or reactive ions at the magnetic separation position of the magnetic recording track and the servo signal pattern portion. This can also be realized. That is, the modification of the magnetic characteristics of the magnetic layer 220 includes realization by modification of the crystal structure of the magnetic layer 220. Here, making the magnetic layer 220 amorphous means that the atomic arrangement of the magnetic layer 220 is in the form of an irregular atomic arrangement having no long-range order, and more specifically less than 2 nm. It refers to a state in which microcrystal grains are randomly arranged. When this atomic arrangement state is confirmed by an analysis method, a peak representing a crystal plane is not recognized by X-ray diffraction or electron beam diffraction, and only a halo is recognized.

Examples of the reactive plasma used when modifying the magnetic layer 220 include inductively coupled plasma (ICP) and reactive ion plasma (RIE). Moreover, the reactive ion can illustrate the reactive ion which exists in the above-mentioned inductively coupled plasma and reactive ion plasma.
The inductively coupled plasma is a high-temperature plasma obtained by generating a plasma by applying a high voltage to a gas and generating Joule heat due to an eddy current in the plasma by a high-frequency variable magnetic field. The inductively coupled plasma has a high electron density, and the magnetic characteristics can be improved with high efficiency in the magnetic layer 220 having a large area as compared with the case where a discrete track medium is manufactured using a conventional ion beam. The reactive ion plasma is a highly reactive plasma in which a reactive gas such as O ₂ , SF ₆ , CHF ₃ , CF ₄ , or CCl ₄ is added to the plasma. By using such plasma as reactive plasma, it is possible to realize the modification of the magnetic characteristics of the magnetic layer 220 with higher efficiency.

In this production method, the reactive plasma or reactive ions preferably contain halogen ions, and the halogen ions are any selected from the group consisting of CF ₄ , SF ₆ , CHF ₃ , CCl ₄ , and KBr. The halogen ion formed by introducing one or more halogenated gases into the reactive plasma increases the reactivity between the magnetic layer 220 and the plasma, and further improves the accuracy of the pattern to be formed. Is preferable. Although the details of this reason are not clear, the halogen atoms in the reactive plasma etch foreign matter formed on the surface of the magnetic layer 220, thereby cleaning the surface of the magnetic layer 220 and reacting the magnetic layer 220. It is considered that the property is increased. Further, it is conceivable that the cleaned magnetic layer 220 surface reacts with halogen atoms with high efficiency.

  In this manufacturing method, the magnetic layer 220 is modified by exposing the deposited magnetic layer 220 to reactive plasma. This modification is performed by modifying the magnetic metal constituting the magnetic layer 220 and atoms in the reactive plasma. It is preferably realized by reaction with ions. As the reaction here, atoms in the reactive plasma enter the magnetic metal, the crystal structure of the magnetic metal changes, the composition of the magnetic metal changes, the magnetic metal oxidizes, the magnetic metal Examples include nitriding, silicidation of magnetic metal, and the like.

  In this manufacturing method, thereafter, as shown in Step H, the resist film 240 and the mask layer 230 are removed. In this step, techniques such as dry etching, reactive ion etching, ion milling, and wet etching can be used.

In this manufacturing method, thereafter, as shown in step I, the magnetic layer 220 activated in the steps F, G, and H is irradiated with an inert gas to stabilize the magnetic layer 220. By providing such a process, it is not clear why the magnetic layer 220 is stabilized and the occurrence of magnetic particle migration or the like is suppressed even in a high-temperature and high-humidity environment, but an inert element is present on the surface of the magnetic layer 220. It is conceivable that the movement of the magnetic particles is suppressed by the penetration, or that the active surface of the magnetic layer 220 is removed by irradiation with an inert gas, and the migration of the magnetic particles is suppressed.
As the inert gas, it is preferable to use at least one gas selected from the group consisting of Ar, He, and Xe. This is because these elements are stable and highly effective in suppressing migration of magnetic particles. For the irradiation of the inert gas, it is preferable to use any method selected from the group consisting of an ion gun, ICP, and RIE. Among these, it is particularly preferable to use ICP or RIE in terms of a large amount of irradiation. ICP and RIE are as described above.

In this manufacturing method, as shown in Step I, it is preferable to manufacture a magnetic recording medium by forming a protective film 290 and then applying a lubricant. The formation of the protective film 290 is generally not particularly limited, although a method of forming a thin film of Diamond Like Carbon using P-CVD or the like is performed. The protective film includes carbonaceous layers such as carbon (C), hydrogenated carbon (H _x C), nitrogenated carbon (CN), alumocarbon, silicon carbide (SiC), SiO ₂ , Zr ₂ O ₃ , TiN. For example, a commonly used protective film material can be used. Further, the protective film may be composed of two or more layers.
The thickness of the protective film 290 needs to be less than 10 nm. This is because if the thickness of the protective film exceeds 10 nm, the distance between the head and the magnetic layer 220 increases, and sufficient input / output signal strength cannot be obtained.
A lubricating layer is preferably formed on the protective film 290. Examples of the lubricant used for the lubricating layer include a fluorine-based lubricant, a hydrocarbon-based lubricant, and a mixture thereof, and the lubricating layer is usually formed with a thickness of 1 to 4 nm.

In this method of manufacturing a magnetic recording medium, when transferring the concave / convex pattern of the master mold 250 to the resist film 240, radiation for curing the resist film 240 can be irradiated from the back surface of the mold 250. As a result, the mask layer 230 for forming the magnetic recording pattern on the surface of the magnetic layer 220 can be formed in a short time, and the productivity of the magnetic recording medium can be increased.
Furthermore, in the above method, the recording density of the magnetic recording medium can be improved because the mold in which the concave / convex pattern of the master mold is transferred with high accuracy is used.

The method for manufacturing the magnetic recording medium includes a step F of ion milling, but the step F may be omitted. When the process F is omitted, the surface from which the mask is removed and the magnetic layer 220 is exposed is exposed to reactive plasma or reactive ions.
Further, in this method of manufacturing a magnetic recording medium, a step of applying a resist to the magnetic layer 220, a step of pressing a resin mold on which a concavo-convex pattern is formed, and a step of transferring the concavo-convex pattern of the mold to the resist Can be performed simultaneously on both sides of the substrate. This is because the mold in the present invention is easy to handle because it is in the form of a highly flexible film, and since this film can be elongated, the supply of the mold to both surfaces of the magnetic recording medium substrate, This is because they can be easily transferred, peeled off and collected.

(Use of magnetic recording media)
The magnetic recording medium obtained by the above manufacturing method is used in a magnetic recording / reproducing apparatus or the like.
An example of a magnetic recording / reproducing apparatus using a magnetic recording medium is shown in FIG. The magnetic recording / reproducing apparatus includes the above-described magnetic recording medium 300 of the present invention, a medium driving unit 400 that drives the magnetic recording medium 300 in the recording direction, a magnetic head 500 including a recording unit and a reproducing unit, and the magnetic head 500 as a magnetic recording medium. And a recording / reproducing signal system 700 that combines a signal input to the magnetic head 500 and recording / reproducing signal processing means for reproducing an output signal from the magnetic head 500. Is. By combining these, it is possible to configure a magnetic recording apparatus with a high recording density. By processing the recording track of the magnetic recording medium magnetically discontinuously, conventionally, the reproducing head width was made narrower than the recording head width in order to eliminate the influence of the magnetization transition region at the track edge portion. Can be operated with both of them approximately the same width. As a result, sufficient reproduction output and high SNR can be obtained.
Furthermore, by configuring the reproducing section of the magnetic head as a GMR head or TMR head, a sufficient signal intensity can be obtained even at a high recording density, and a magnetic recording apparatus having a high recording density can be realized. . Further, when the flying height of the magnetic head is 0.005 μm to 0.020 μm, when the flying height is lower than the conventional height, the output is improved and a high device SNR can be obtained, and a large capacity and high reliability magnetic recording device can be obtained. Can be provided. Further, by combining the signal processing circuit based on the maximum likelihood decoding method, the recording density can be further improved. For example, the track density is 100 k tracks / inch or more, the linear recording density is 1000 k bits / inch or more, and the recording density is 100 G bits or more per square inch. A sufficient SNR can also be obtained when recording / reproducing.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.
(Preparation of curable resin material)
77.4 parts by mass of beam set 371 (manufactured by Arakawa Chemical Industries), 6.0 parts by mass of 25% by mass acetone solution of Irgacure 127 (manufactured by Ciba Specialty Chemicals), Megafac R-30 (DIC Corporation) Made of 2.5) parts by mass and 16.4 parts by mass of ethyl acetate (diluting solvent) to prepare an ultraviolet curable resin material solution.
The viscosity of this curable resin material is 59.1 mPa · s, and the cured product after curing has a transmittance of 65% at a wavelength of 365 nm and a tensile elastic modulus at a temperature of 25 ° C. of 0.03 GPa.

(Manufacture of laminated film)
The obtained solution of the curable resin material was applied onto a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., thickness 50 μm, width 100 mm, length 1000 m) which was a base film subjected to an easy adhesion treatment.
Next, the diluted solvent was volatilized to form a layer (viscosity: 2 Pa · s) of an ultraviolet curable resin material having a thickness of 30 μm.
Next, a laminated film in which a polyethylene terephthalate film (thickness 16 μm) treated with silicone as a cover film is bonded onto the curable resin material layer, and the curable resin material layer is sandwiched between the base film and the cover film. Got.

(Encapsulation of curable resin material)
Using a cylindrical winding core made of ABS resin, 1080 mm is formed by irradiating ultraviolet rays (365 nm, 36 mW / m ² ) with a width of 90 mm × 10 mm at both ends in the width direction of the obtained laminated film to form a flow inhibitor. Winding up at a winding speed of / min. Thereby, the roll of the laminated body which was 150 m in length and 100 mm in width, and 10 mm of both ends of the width direction was hardened, and became a flow suppression body was obtained.

(Manufacture of replica molds)
The replica mold was manufactured using the roll and master mold of the obtained laminated body.
As the master mold, a number of concentric circular patterns having a concave / convex height of 80 nm, a convex width of 120 nm, and a concave width of 80 nm were formed on the surface of a nickel electroformed donut board having a thickness of 0.3 mm, an inner diameter of 16 mm, and an outer diameter of 63.5 mm. A stamper was used.
The master mold was mounted on a stamper device with the pattern surface facing down. Next, the laminate was supplied so that the surface of the cover film faced the pattern surface of the master mold with the surface of the cover film facing up.
Subsequently, the cover film was peeled from the laminate, and the master mold was pressed against the layer of the curable resin material at a pressure of 30 MPa for 10 seconds. In this state, the curable resin material was cured by irradiating with ultraviolet rays for 20 seconds by an ultraviolet irradiation device (LED lamp with a wavelength of 365 nm) having an illuminance set to 30 mW / cm ² . Then, the irradiation of ultraviolet rays was stopped, the master mold was raised, and a replica mold in which the pattern was transferred to the layer of the curable resin material was obtained. This process was continuously performed to obtain 1500 replica molds from the roll of the laminate.

(Preparation of magnetic recording medium substrate with resist film)
A glass substrate for a magnetic recording medium was placed in a vacuum chamber, and the inside of the vacuum chamber was evacuated to 1.0 × 10 ⁻⁵ Pa or less. The glass substrate used here is composed of Li ₂ Si ₂ O ₅ , Al ₂ O ₃ —K ₂ O, Al ₂ O ₃ —K ₂ O, MgO—P ₂ O ₅ , and Sb ₂ O ₃ —ZnO. It is made of crystallized glass and has an outer diameter of 65 mm, an inner diameter of 20 mm, and an average surface roughness (Ra) of 2 angstroms.
Using a DC sputtering method, thin films are laminated on the glass substrate in the order of 65Fe-30Co-5B as a soft magnetic layer, Ru as an intermediate layer, and 74Co-6Cr-18Pt-2SiO ₂ (these are in a molar ratio) alloy as a magnetic layer. did. The thickness of each layer was 60 nm for the FeCoB soft magnetic layer, 10 nm for the Ru intermediate layer, and 15 nm for the magnetic layer. A mask layer was formed thereon using a sputtering method. Ta was used for the mask layer, and the film thickness was 60 nm. A resist was applied to both surfaces of the magnetic recording medium by spin coating to form a resist film. As the resist, PAK-01 (manufactured by Toyo Gosei Co., Ltd.), which is an ultraviolet curable resin, was used. The film thickness was adjusted by diluting the resin with a solvent so as to be 100 nm.

<Imprint using resin mold>
The resin replica mold was sandwiched on both sides of the magnetic recording medium substrate by a quartz jig so that the surface of the concavo-convex pattern was opposed to the resist film of the magnetic recording medium substrate. One of the quartz jigs is vertically provided with a cylindrical rod having a diameter of 20 mm for positioning the magnetic recording medium substrate and the resin replica mold. After pressing these two quartz jigs for 10 seconds at a pressure of 0.6 MPa, ultraviolet light with an illuminance of 30 mW / cm ² was irradiated from the quartz jig side with an LED lamp having a wavelength of 365 nm without changing the pressure. . Thereafter, the replica mold was peeled off from the magnetic recording medium substrate, and the mold was recovered by a film winder.
The thickness of the resist film on the substrate surface was 80 nm, and the thickness of the concave portion of the resist film was about 5 nm. The angle of the resist film recess formation method with respect to the substrate was approximately 90 degrees.

<Formation and characteristic evaluation of magnetic recording pattern>
Thereafter, the concave portion of the resist film and the Ta layer therebelow were removed by dry etching. As for dry etching conditions, O ₂ gas is 40 sccm, pressure is 0.3 Pa, high-frequency plasma power is 300 W, DC bias is 30 W, etching time is 10 seconds for resist etching, and CF ₄ gas is 50 sccm for Ta layer etching. The pressure was 0.6 Pa, the high-frequency plasma power was 500 W, the DC bias was 60 W, and the etching time was 30 seconds.
Thereafter, the surface of the portion not covered by the mask layer with the magnetic layer was removed by ion milling. Ar ions were used for ion milling. The ion milling conditions were a high frequency discharge power of 800 W, an acceleration voltage of 500 V, a pressure of 0.014 Pa, an Ar flow rate of 5 sccm, a treatment time of 40 seconds, and a current density of 0.4 mA / cm ² . The surface subjected to ion milling was exposed to reactive plasma, and the magnetic properties of the magnetic layer were modified. The reactive plasma treatment of the magnetic layer was performed using an inductively coupled plasma apparatus NE550 manufactured by ULVAC. As gas and conditions used for generating plasma, CF ₄ was introduced at a flow rate of 90 cc / min, the input power for generating plasma was 200 W, the pressure in the apparatus was 0.5 Pa, and the magnetic layer was processed for 300 seconds. .

Thereafter, the resist film and the mask layer were removed by dry etching. The dry etching conditions were SF ₆ gas of 100 sccm, pressure of 2.0 Pa, high frequency plasma power of 400 W, and processing time of 300 seconds. Thereafter, the surface of the magnetic layer was irradiated with inert gas plasma. The irradiation conditions of the inert gas plasma were as follows: inert gas 5 sccm, pressure 0.014 Pa, acceleration voltage 300 V, current density 0.4 mA / cm ² , and processing time 10 seconds. A carbon (DLC: diamond-like carbon) protective film having a thickness of 4 nm was formed on the surface by CVD, and then a lubricant was applied to manufacture a magnetic recording medium.

  The defect rate of the formed pattern was examined for the magnetic recording medium manufactured in the example. The defect rate was calculated as a defective product having a pattern formation defect in 3% or more of the tracks formed on the surface of the magnetic recording medium. As a result, the defect rate of the magnetic recording medium manufactured using the resin mold of this example was 3.3%, and the magnetic recording medium could be manufactured with high productivity and high accuracy.

It is sectional drawing which shows one embodiment of the laminated body used with the manufacturing method of the magnetic-recording medium of this invention. It is a figure explaining an example of the layer of a curable resin material, and a flow suppression body. It is a figure explaining the other example of the layer of curable resin material, and a flow suppression body. It is sectional drawing which shows an example of the apparatus which produces resin-made replica molds. It is a figure which shows the lower surface of the upper mold | type set which comprises the apparatus shown in FIG. It is a figure which shows the upper surface of the lower mold | type set which comprises the apparatus shown in FIG. It is a figure which shows 1 process in an example of the production methods of resin molds. It is a figure which shows 1 process in an example of the production methods of resin molds. It is a figure which shows 1 process in an example of the production methods of resin molds. It is a figure which shows 1 process in an example of the production methods of resin molds. It is a figure which shows 1 process in an example of the production methods of resin molds. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows 1 process in one Embodiment of the manufacturing method of the magnetic-recording medium of this invention. It is a figure which shows a long mold. It is a figure which shows typically an example of a magnetic recording / reproducing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10a Laminated body 11,12 Base | substrate 13 Layer of curable resin material 14 1st flow suppression body 15 2nd flow suppression body 20 Master mold 30 Resin mold (mold)
DESCRIPTION OF SYMBOLS 100 Resin mold production apparatus 110 Upper mold set 111 1st mounting board 111a, 111b Through-hole 112 Cutter set member 114 Outer peripheral cutter part 114a Inner peripheral surface 115 Inner peripheral cutter part 116 Cutter member 117 Outer peripheral cutter blade 117a Cutting edge surface 117b Outer blade surface 118 Inner peripheral cutter blade 118a Cutting blade surface 118b Recess 120 Lower mold set 121 Second mounting plate 130 Radiation source support mechanism 140 Irradiation device 150 Support member 160 Radiation-pressing base 170 Inner sliding support member (support member)
171 Recess 180 Outer sliding support member (support member)
190 cradle 191 elastic member 210 substrate 220 magnetic layer 230 mask layer 240 resist film 250 mold 260 milling ion 290 protective film 300 magnetic recording medium 400 medium driving unit 500 magnetic head 600 head driving unit 700 recording / reproducing signal system

Claims (6)

A step of forming a magnetic layer on at least one surface of the substrate, a step of forming a resist film on the surface of the magnetic layer, a resin mold having a concavo-convex pattern is pressed against the resist film, and the concavo-convex pattern of the mold is transferred to the resist film A method of manufacturing a magnetic recording medium having a magnetically separated magnetic recording pattern, including a step, a step of peeling a mold from a resist film, and a step of forming a magnetic recording pattern on a magnetic layer using a transferred concavo-convex pattern There,
The mold is
A step of sandwiching a liquid or gel-like curable resin material between a pair of substrates facing each other and curing only the peripheral portion of the curable resin material to obtain a laminate,
Peeling one of the substrates from the laminate to expose a layer of the curable resin material,
A step of pressing a master mold having a concavo-convex pattern onto the layer of the curable resin material that is exposed;
A step of curing the layer of the curable resin material while pressing the master mold to obtain a resin mold;
A method of manufacturing a magnetic recording medium, wherein the method is manufactured through a process of peeling a resin mold from a master mold.   The method for producing a magnetic recording medium according to claim 1, wherein the viscosity of the liquid or gel-like curable resin material is 10 Pa · s or less.   The curable resin material is a resin material having one or more reactive groups selected from the group consisting of a (meth) acryl group, an oxetanyl group, a cyclohexene oxide group, and a vinyl ether group. A method for producing the magnetic recording medium according to claim.   The curable resin material is a radiation curable resin material that is curable with respect to a wavelength within a range of 300 nm to 400 nm, and a cured product obtained by curing the curable resin material by radiation irradiation. The method for manufacturing a magnetic recording medium according to claim 1, wherein the method is a magnetic recording medium.   The resin after curing of the curable resin material has a transparency of a wavelength in the range of 300 nm to 400 nm of 20% or more and a tensile elastic modulus at a temperature of 25 ° C of 1.3 GPa or more. 5. The method for producing a magnetic recording medium according to any one of 4 above.   6. The process of transferring a concavo-convex pattern of a mold to a resist film, wherein the resist film is cured by irradiation with radiation having a wavelength within a range of 300 nm to 400 nm. Manufacturing method of magnetic recording medium.

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