JP2008276906A - Mold structure, imprinting method using the same, magnetic recording medium and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold structure which is highly durable and excellent in the transfer quality of a pattern to a substrate and which allows a high-quality pattern to be transferred and formed on discrete track media and patterned media. <P>SOLUTION: The mold structure is provided which includes a concavo-convex pattern formed on its surface, wherein the mold structure is used for transferring the concavo-convex pattern onto an imprint resist layer formed on a surface of a substrate having a thickness of 0.3 mm to 2.0 mm by placing the concavo-convex pattern against the imprint resist layer, and wherein a thickness (Dm) of the mold structure, a thickness (Ds) of the substrate and an area (S<SB>1</SB>) of the mold structure satisfy the relationship 0.5≤(Dm/Ds)×S<SB>1</SB><SP>1/2</SP>≤100. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold structure having a concavo-convex pattern for transferring information to a magnetic recording medium, an imprint method using the same, a magnetic recording medium, and a method for manufacturing the same.

In recent years, hard disk drives with excellent speed and cost have been installed in portable devices such as mobile phones, small audio devices, and video cameras as the mainstay of storage devices, in order to meet the demand for further miniaturization and larger capacity. In addition, a technique for improving the recording density is required.
In order to increase the recording density of the hard disk drive, methods of improving the performance of the magnetic recording medium and narrowing the magnetic head width have been used conventionally. However, by reducing the data track interval, the magnetic field between adjacent tracks can be reduced. (Crosstalk) and thermal fluctuation cannot be ignored, and there is a limit to the improvement of the surface recording density by narrowing the magnetic head.

Therefore, a magnetic recording medium called a discrete track medium has been proposed as means for solving noise caused by crosstalk (see Patent Documents 1 and 2).
Discrete track media have a discrete structure in which nonmagnetic guard band regions are provided between adjacent tracks to magnetically separate individual tracks, thereby reducing magnetic interference between adjacent tracks.

  As a means for solving demagnetization due to 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 (see Patent Document 3). ).

  When manufacturing the above discrete track media or patterned media, as disclosed in Patent Document 4, it is formed on the surface of a magnetic recording medium using a resist pattern forming mold (also referred to as a stamper). There is an imprinting method for transferring a desired pattern to the resist layer.

  By the way, in the use of a magnetic recording medium, since it is necessary to perform nanoimprint lithography (NIL) on a fine and wide area, NIL uniformity and stability are important. Also, it is necessary to process two types of patterns: a servo signal for positioning the magnetic head and a data signal for recording actual data. The data portion is composed of a simple pattern such as a concentric circle pattern in discrete track media (DTM) and a dot pattern in bit patterned media (BPM). The servo part is composed mainly of 4 types of patterns such as preamble, servo timing mark, address (sector, cylinder), burst, etc. The address (sector, cylinder), burst pattern part is mixed with coarse signal and complicated It is a pattern array.

  Since complex patterns are densely formed on the entire disk surface as described above, it is required that the uneven pattern of the mold structure be faithfully transferred to the entire imprint resist layer during NIL.

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

  Therefore, in order to improve the transfer durability, a technique is disclosed in which a rigid body such as a silicon substrate is employed in the 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.

Here, in a rigid and thick mold structure such as a silicon substrate, the imprint resist layer to be imprinted cannot follow various shapes of the substrate formed on the surface, and it is difficult to uniformly transfer the entire surface.
Further, when the imprint area is increased, the flatness of the mold structure becomes a problem, and uniform pattern transfer becomes difficult.
Furthermore, when the thickness of the mold structure is thick, the weight increases, the handling property deteriorates, and the suitability of the production process becomes a problem.
On the other hand, when the substrate thickness is reduced, the above problem is solved, but the mold structure itself may be deformed or damaged, that is, durability may be reduced (see Patent Document 6).

  Therefore, durability and transferability to the substrate are high, and a mold structure for transferring and forming a high-quality pattern on discrete track media, patterned media, and related technologies have not been realized yet, and the provision thereof is hoped for. The current situation is rare.

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 JP 2004-288845 A S. Y. Chou, et al. , Appl. Phys. Lett. , Vol. 67, 3314, 1995

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention has high durability and transferability to a substrate, and a discrete track medium, a mold structure that transfers and forms a high-quality pattern on a patterned medium, an imprint method using the mold structure, and a magnetic recording medium And it aims at providing the manufacturing method.

  As a result of intensive studies, the inventors have reduced the thickness of the mold structure and increased the thickness of the substrate so that the mold structure can easily follow the substrate during the imprint process, and the mold structure is thin. It has been found that the above-mentioned problems can be solved by increasing the area of the mold structure to reduce the strength of the concave-convex pattern.

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> With respect to a substrate having a thickness of 0.3 mm to 2.0 mm and having an imprint resist layer formed on the surface, an uneven pattern is formed on the surface, and the uneven pattern is opposed to the imprint resist layer. A mold structure for transferring the concavo-convex pattern to the imprint resist layer, the thickness Dm (mm) of the mold structure, the thickness Ds (mm) of the substrate, and the area S ₁ (mm of the mold structure) ² ) is a mold structure characterized by satisfying the following mathematical formula (1).
0.5 ≦ (Dm / Ds) × S ₁ ^1/2 ≦ 100... Equation (1)
In the mold structure according to <1>, an appropriate value for the thickness of the mold structure is specified by defining a relationship between the thickness of the mold structure, the thickness of the substrate, and the area of the mold structure. Since the handling property is improved, the durability and the transfer property to the substrate are high, and a mold structure that transfers and forms a high-quality pattern on a discrete track medium or a patterned medium can be provided. .
<2> The thickness Dm (mm) of the mold structure, the thickness Ds (mm) of the substrate, the area S ₁ (mm ² ) of the mold structure, and the surface area S ₂ (mm ² ) of the concavo-convex pattern The mold structure according to <1>, which satisfies (2).
0.01 ≦ (Dm / Ds) × (S ₂ / S ₁ ) ^1/2 ≦ 1... Equation (2)
<3> The mold structure according to any one of <1> to <2>, wherein the thickness is 0.01 mm or more and less than 0.5 mm.
<4> The mold structure according to any one of <1> to <3>, which is made of any material of quartz, nickel, and resin.

<5> A mold structure having a concavo-convex pattern formed on the surface of a substrate having an imprint resist layer formed on the surface, the concavo-convex pattern on the imprint resist with the concavo-convex pattern opposed to the imprint resist layer. An imprint method including at least a transfer step of transferring a pattern, wherein the mold structure has a thickness Dm (mm), the substrate has a thickness Ds (mm), and an area S ₁ (mm ² ) of the mold structure. Is an imprint method characterized by satisfying the following mathematical formula (1).
0.5 ≦ (Dm / Ds) × S ₁ ^1/2 ≦ 100... Equation (1)

<6> An uneven pattern formed on the mold structure by pressing the mold structure according to any one of <1> to <4> against an imprint resist layer formed on a substrate of a magnetic recording medium. And a magnetic pattern portion based on the concavo-convex pattern by 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. A magnetic pattern portion forming step of forming a magnetic layer on the magnetic layer, and a nonmagnetic pattern portion forming step of embedding a nonmagnetic material in a recess formed on the magnetic layer. Is the method.
<7> A magnetic recording medium produced by the method for producing a magnetic recording medium according to <6>.

<8> A method of manufacturing a magnetic recording medium, wherein the magnetic recording medium is manufactured using the imprint method according to <5>.
<9> The method for producing a magnetic recording medium according to <8>, wherein the magnetic recording medium is at least one of a discrete magnetic recording medium and a patterned media magnetic recording medium.

<10> A magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium according to any one of <8> to <9>.
<11> The magnetic recording medium according to <10>, which is at least one of a discrete magnetic recording medium and a patterned media magnetic recording medium.

  According to the present invention, various problems in the prior art can be solved, durability and transferability to a substrate are high, and a mold structure that transfers and forms a high-quality pattern on a discrete track medium or patterned medium, and the same are used. An imprint method, a magnetic recording medium, and a manufacturing method thereof can be provided.

  Hereinafter, the DTM mold structure in the present invention will be described with reference to the drawings.

<Configuration of mold structure>
FIG. 1 is a partial perspective view showing a configuration in an embodiment of a mold structure according to the present invention.
As shown in FIG. 1, in the mold structure 1 of the present embodiment, a plurality of convex portions 3a are concentrically formed on one surface 2a (hereinafter, also referred to as a reference surface 2a) of a substrate 2 having a disc shape. And formed at a predetermined interval. The convex portion is provided corresponding to the servo portion and the data portion of the magnetic recording medium. The data portion is an area in which data is recorded, having a substantially concentric convex pattern. The servo part is composed of a plurality of types of convex patterns having different convex part areas. The servo unit corresponds to a tracking servo control signal, and mainly includes, for example, a preamble, a servo timing mark, an address pattern, a burst pattern, and the like. The preamble pattern is a part that generates a reference clock signal for reading various control signals from an address pattern region or the like. The servo timing mark is a trigger signal for reading an address and a burst pattern. The address mark is composed of sector (angle) information and track (radius) information, and indicates the absolute position (address) of the disk. The burst pattern has a function of finely adjusting the head traveling position to achieve highly accurate positioning when the magnetic head is in an on-track state.
There is no restriction | limiting in particular as the board | substrate 2 material of the said mold structure, Although it can select suitably according to the objective, Any material of quartz, a metal, and resin is suitable.
As said metal, various metals, such as Ni, Cu, Al, Mo, Co, Cr, Ta, Pd, Pt, Au, or these alloys can be used, for example. Among these, Ni and Ni alloys are particularly preferable.
Examples of the resin include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), triacetate cellulose (TAC), and a low melting point fluororesin.

In the present embodiment, the convex portion 3 a and the concave portion 3 b formed between the plurality of convex portions 3 a are collectively referred to as the concave and convex portion 3.
Moreover, the cross-sectional shape of the convex part 3a in the radial direction of the concentric circle (direction in which the convex parts 3a are arranged) is, for example, a rectangle.
In addition, the cross-sectional shape of the said convex part 3a is not restricted to a rectangle, According to the objective, arbitrary shapes can be selected by controlling the etching process mentioned later.
Hereinafter, in the description of the present embodiment, “cross section (shape)” refers to a cross section (shape) in the radial direction of the concentric circles (direction in which the convex portions 3 a are arranged) unless otherwise specified.

The mold structure 1 of the present invention is imprinted by the mold structure 1 with the thickness of the substrate 2 being Dm (mm) and the projected area from the normal direction on the surface of the substrate 2 being S ₁ (mm ² ). When the thickness of the substrate on which the imprint resist layer is formed is Ds (mm), the thickness Dm of the mold structure 1 preferably satisfies the following mathematical formula (1). However, 0.3 ≦ Ds ≦ 2.0. If the thickness Ds of the substrate is less than 0.3 mm, the rigidity of the substrate itself is lowered, and there is a problem that stable flying of the magnetic head can be obtained due to surface deflection during high-speed rotation. Further, if the thickness Ds of the substrate exceeds 2.0 mm, there is a problem that not only the weight increases and the product suitability is low, but also the material cost increases.
Further, the surface area S ₁ is more preferably 1,000 (mm ² ) or more.

0.5 ≦ (Dm / Ds) × S ₁ ^1/2 ≦ 100... Equation (1)

Further, in the mold structure 1 of the present invention, when the area of the top of the convex portion 3a constituting the concave / convex pattern is S ₂ (mm ² ), the thickness Dm of the mold structure 1 is expressed by the following mathematical formula (2). It is more preferable to satisfy.
Here, the surface area S ₂ is the top of all of the convex portions 3a, was calculated by approximating a plane parallel to the surface where the convex portions 3a of the substrate 2 are formed (the reference surface 2a, see Fig. 1) It refers to the area and is measured from a cross-sectional SEM or cross-sectional TEM image.

0.01 ≦ (Dm / Ds) × (S ₂ / S ₁ ) ^1/2 ≦ 1... Equation (2)

  Moreover, it is preferable that the thickness of the board | substrate 2 is 0.01 mm or more and less than 0.5 mm.

(Mold structure manufacturing method)
Hereinafter, a method for producing a mold structure according to the present invention will be described with reference to the drawings.

<First Embodiment>
<< Preparation of master disk >>
2A and 2B are cross-sectional views showing a method for producing a mold structure according to the first embodiment. As shown in FIG. 2A, first, a photoresist solution such as PMMA is applied on the Si substrate 10 by spin coating or the like to form a photoresist layer 21.
Thereafter, while rotating the Si substrate 10, a laser beam (or electron beam) modulated corresponding to at least one of the data recording track and the servo signal is irradiated, and a predetermined pattern, for example, a substantially concentric circular shape, is applied to the entire surface of the photoresist. A data track pattern consisting of a plurality of convex patterns, a servo pattern consisting of a plurality of types of convex patterns having different convex areas, and a substantially radial convex pattern connected in a radial direction between the data track pattern and the servo pattern. The buffer pattern is exposed.
Thereafter, the photoresist layer 21 is developed, the exposed portion is removed, selective etching is performed by RIE or the like using the pattern of the removed photoresist layer 21 as a mask, and an uneven pattern is formed on the substrate 10. Next, the remaining resist layer 21 is removed to obtain a master 11 having an uneven shape.

<< Production of mold structure >>
Next, as shown in FIG. 2B, for example, a quartz substrate 30 as a substrate to be processed on which an imprint resist layer 24 formed by applying an imprint resist solution containing a photocurable resin is formed on one surface. Then, the master 11 is pressed, and the pattern of the protrusions formed on the master 11 is transferred to the imprint resist layer 24.

<< imprint resist layer >>
The imprint resist layer includes, for example, an imprint resist composition containing at least one of a thermoplastic resin, a thermosetting resin, and a photocurable resin (hereinafter sometimes referred to as “imprint resist solution”). It is a layer formed by applying to a substrate, a magnetic recording medium or the like.

  The thickness of the imprint resist layer can be measured, for example, by optical measurement using an ellipsometer or the like, contact measurement using a stylus type step gauge, an atomic force microscope (AFM), or the like.

  In addition, as the imprint resist composition, those having thermoplasticity, those having photocurability, sol-gel, or the like are used. A novolak resin, an epoxy resin, an alicyclic resin, or a fluorine-based resin with good peelability having these characteristics and high dry etching resistance is suitable.

Here, the material of the substrate to be processed in the present invention is appropriately selected according to the purpose without any particular limitation as long as it is a material having optical transparency and functioning as a mold structure. , Quartz (SiO ₂ ), organic resins (PET, PEN, polycarbonate, low melting point fluororesin, PMMA) and the like.

  Further, the “having light transmittance” specifically means that light is emitted from the other surface of the substrate to be processed so that the light is emitted from one surface on which the imprint resist layer is formed on the substrate to be processed. This means that the imprint resist is sufficiently cured when incident, and at least the light transmittance from the other surface to the one surface is 50% or more.

Further, “having the strength to function as a mold structure” means that the imprint resist layer formed on the substrate of the magnetic recording medium is pressed against the imprint resist layer under the condition that the average surface pressure is 4 kgf / cm ² . It means strength that can withstand pressure.

<< Curing process >>
Thereafter, the transferred pattern is cured by irradiating the imprint resist layer 24 with ultraviolet rays or the like.

<< 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.
The selective etching is performed so that the cross-sectional shape of the concave portion of the mold structure 1 having the concavo-convex shape is a cross-sectional shape obtained by transferring the cross-sectional shape of the convex portion 3a shown in FIG.

<< Peeling layer forming process >>
A release agent layer is formed on the irregular surface of the produced mold structure. The release agent is preferably formed on the surface of the mold structure so that it can be peeled off at the interface between the mold structure and the imprint resist layer after imprinting. The release agent material can be appropriately selected as long as it meets the purpose of being easily adhered and bonded to the mold structure and hardly adsorbed on the surface of the imprint resist layer. Among these, a fluorine-based resin is preferable in that it hardly adheres to the resist layer surface.

When the release agent layer is thick, the pattern accuracy deteriorates. Therefore, it is preferable to make the layer as thin as possible, specifically 10 nm or less, more preferably 5 nm or less.
As a means for forming the release agent layer, a coating or vapor deposition means can be used. Further, after the release agent layer is formed, a step of increasing the adsorptivity to the mold structure by means such as baking may be applied.

<Second Embodiment>
<< Preparation of master disk >>
3A and 3B are cross-sectional views illustrating a method for producing a mold structure according to the second embodiment. A master 11 having a concavo-convex pattern was produced as in the first embodiment.

<< Production of mold structure >>
A conductive film was formed on the surface of the master by a sputtering method, and the master provided with the conductive film was immersed in a Ni electroforming bath and subjected to electroforming to prepare a Ni mold structure.
The conductive film 22 can be formed on the concavo-convex pattern of the master 11 by using a conductive material as a vacuum film forming means such as a vacuum deposition method, a sputtering method or an ion plating method, a plating method, or the like. The conductive material can be appropriately selected according to the post-process (electroforming), but Ni-based, Fe-based, Co-based metals or alloy materials are preferable. The thickness of the Ni mold structure obtained by electroforming is preferably in the range of 20 to 800 μm, more preferably 40 to 400 μm.

<< Peeling layer forming process >>
As in the first embodiment, it is preferable to form a release agent layer on the surface of the Ni mold structure.

<Third Embodiment>
<< Preparation of master disk >>
4A and 4B are cross-sectional views illustrating a method for producing a mold structure according to the third embodiment. A master 11 having a concavo-convex pattern was produced as in the first embodiment.

<< Production of mold structure >>
The master was pressed against the thermoplastic resin sheet. Then, by heating to a temperature equal to or higher than the softening point of the resin, the viscosity of the resin was lowered, and the pattern of the protrusions formed on the master was transferred to the resin sheet. Then, the pattern transferred by cooling was cured, and the resin sheet was peeled from the master to produce a resin mold structure having an uneven shape.

  Here, the resin material is appropriately selected according to the purpose without particular limitation as long as it is a material having thermoplasticity, light transmittance, and strength that functions as a mold structure. For example, PET , PEN, polycarbonate, low melting point fluororesin, PMMA and the like.

  Further, the “having light transmittance” specifically means that light is emitted from the other surface of the substrate to be processed so that the light is emitted from one surface on which the imprint resist layer is formed on the substrate to be processed. This means that the imprint resist is sufficiently cured when incident, and at least the light transmittance from the other surface to the one surface is 50% or more.

Further, “having the strength to function as a mold structure” means that the imprint resist layer formed on the substrate of the magnetic recording medium is pressed against the imprint resist layer under the condition that the average surface pressure is 4 kgf / cm ² . It means strength that can withstand pressure.

<< Peeling layer forming process >>
As in the first embodiment, it is preferable to form a release agent layer on the surface of the resin mold structure.
The mold structure of the present invention is suitably used for an imprint method including at least a transfer step of transferring the concavo-convex pattern to the resist layer with the convex portion of the mold structure facing the resist layer, which will be described below. It is particularly suitable for the method for producing a magnetic recording medium of the present invention.

<Method for producing magnetic recording medium>
The method for producing a magnetic recording medium of the present invention is a method for transferring a concavo-convex pattern formed on the mold structure by pressing the mold structure of the present invention against an imprint resist layer formed on a substrate of the magnetic recording medium. A step of curing the concavo-convex pattern transferred to the imprint resist layer and peeling the mold structure; and a substrate of the magnetic recording medium using the imprint resist layer having the concavo-convex pattern transferred as a mask The magnetic layer formed on the surface of the magnetic layer is etched to form a magnetic pattern portion based on the concavo-convex pattern on the magnetic layer, and a nonmagnetic material is embedded in the concave portion formed on the magnetic layer. A non-magnetic pattern part forming step, and further including other steps as necessary.

  Hereinafter, an example of a method for manufacturing a magnetic recording medium such as a discrete track medium or a patterned medium will be described with reference to the drawings.

[Transfer process]
On a magnetic layer of a magnetic recording medium intermediate having a magnetic layer 50 such as Fe or Fe alloy, Co or Co alloy on a substrate such as aluminum, glass, silicon, or quartz, an inner layer such as polymethyl methacrylate (PMMA) is used. By pressing and pressing the mold structure having a concavo-convex pattern on the surface of the magnetic recording medium intermediate with a resist layer on which a resist layer 24 formed by applying a print resist solution is formed, The concavo-convex pattern formed in (1) is transferred to the resist layer 24.

[Curing process]
-Curing by light irradiation-
When the imprint resist composition for forming the imprint resist layer contains a photocurable resin, the imprint resist layer is irradiated with an electron beam such as ultraviolet rays through the imprint mold structure 1 having transparency. The imprint resist layer is cured.
The photocurable resin used here includes a radical polymerization type and a cationic polymerization type, and can be appropriately selected for the required pattern shape accuracy and curing speed.

―Curing by heating―
When the imprint resist composition for forming the imprint resist layer contains a thermoplastic resin, when the imprint mold structure 1 is pressed against the imprint resist layer, the system is changed to the glass transition point (Tg) of the resist solution. ), The imprint resist layer is cured by lowering the glass transition point of the resist solution after the transfer. Furthermore, the pattern may be cured by irradiating ultraviolet rays or the like as necessary.

  When the imprint resist composition contains a thermosetting resin, the imprint mold structure 1 is pressed against the imprint resist layer in a state where the imprint resist composition exhibits fluidity at room temperature or after heating to transfer the concavo-convex pattern. The imprint resist layer is cured by heating to the curing temperature of the resin.

[Magnetic pattern formation process]
Next, dry etching is performed using the resist layer to which the pattern of the concavo-convex portion is transferred as a mask, thereby forming a concavo-convex shape on the magnetic layer based on the concavo-convex pattern shape formed on the resist layer.

  The dry etching is not particularly limited as long as it can form a concavo-convex shape in the magnetic layer, and can be appropriately selected according to the purpose. Examples thereof include ion milling, reactive ion etching (RIE), and sputter etching. , Etc. Among these, ion milling and reactive ion etching (RIE) are particularly preferable.

  The ion milling method is also called ion beam etching. An inert gas such as Ar is introduced into an ion source to generate ions. This is accelerated through the grid and collides with the sample substrate for etching. Examples of the ion source include a Kaufman type, a high frequency type, an electron impact type, a duoplasmatron source, a Freeman type, an ECR (electron cyclotron resonance) type, and a closed drift type.

As a process gas in ion beam etching, as an etchant for RIE, CO + NH ₃ , chlorine gas, CF-based gas, CH-based gas, and those obtained by adding oxygen, nitrogen, or hydrogen gas to these gases can be used. .

[Non-magnetic pattern part forming process]
Next, after embedding a nonmagnetic material in the formed recess and planarizing the surface, a protective film or the like can be formed as necessary to produce the magnetic recording medium 100.
Examples of the nonmagnetic material include polymers such as SiO ₂ , carbon, alumina, polymethyl methacrylate (PMMA), polystyrene (PS), and smooth oil.
As the protective film, diamond carbon (DLC), sputtered carbon or the like is preferable, and a lubricant layer may be further provided on the protective film.
The magnetic recording medium manufactured by the magnetic recording medium manufacturing method of the present invention is preferably at least one of a discrete magnetic recording medium and a patterned media magnetic recording medium.

Example 1
<Production of mold structure>
2A and 2B are cross-sectional views showing a method for producing a mold structure according to the first embodiment. As shown in FIG. 2A, first, an electron beam resist was applied to a thickness of 100 nm on the Si substrate 10 by spin coating. A resist-patterned Si substrate having a concavo-convex pattern was produced by exposing and developing a desired pattern with a rotary electron beam exposure apparatus.
Thereafter, using the resist pattern as a mask, the following reactive ion etching (RIE) was performed to form a concavo-convex shape on the Si substrate.
Plasma source: ICP type (Inductively Coupled Plasma)
Gas: CF gas and a small amount of hydrogen gas Pressure: 0.5Pa
Input power: ICP-300W, Bias-50W
Thereafter, the remaining resist was removed by washing with a soluble solvent and dried to produce a master.

  The patterns used in this embodiment are roughly divided into a data portion and a servo portion. The data portion was a pattern having a convex width: 120 nm and a concave width: 30 nm (TP = 150 nm). The servo section has a servo basic bit length at the innermost circumference of 90 nm, a total number of sectors of 240, a preamble (45 bits) / servo mark (10 bits) / SectorCode (8 bits), and a CylinderCode (32 bits) / Burst pattern.

  The servo mark part is “0000101011”, the Sector uses Binary, and the Cylinder uses Gray conversion. The Burst part is a general phase burst signal (16 bits).

Next, a photocurable acrylic imprint resist solution (manufactured by Toyo Gosei Co., Ltd .: PAK-01) was formed on a quartz substrate by a 100 nm spin coating method.
Next, UV nanoimprinting was performed using the master as a mold structure. In UV nanoimprinting, pattern transfer was performed by applying pressure at 1 MPa for 5 seconds, and then pattern curing was performed by irradiation with 25 mJ / cm ² of UV light for 10 seconds.
Based on the concavo-convex resist pattern after nanoimprinting, selective etching was performed by RIE shown below to form a concavo-convex shape on the quartz substrate.
Plasma source: ICP type (Inductively Coupled Plasma) Gas: CF gas and Ar gas are added in a 1: 1 ratio, and a small amount of hydrogen gas is added. Pressure: 0.5 Pa
Input power: ICP-300W, Bias-60W
Thereafter, the remaining resist was removed by washing with a soluble solvent and dried to produce a quartz mold. The selective etching is performed so that the cross-sectional shape of the concave portion of the mold structure 1 having a concavo-convex shape is a cross-sectional shape obtained by transferring the cross-sectional shape of the convex portion 3 shown in FIG.

<Peeling layer formation>
A release agent layer was formed on the irregular surface of the produced mold structure by a wet method. F13-OTCS (Tridecafluoro-1,1,2,2-tetrahydro-OctylTriChloroSilane) (manufactured by Gelest) was used as the release agent layer material, and 0.1% by mass of stripped with Asahi Clin AK225 (manufactured by Asahi Glass Co., Ltd.) The layer solution was adjusted. Using this release layer solution, 1 mm / sec. A release layer having a thickness of 5.25 nm was formed on the quartz mold at a pulling speed of.
The mold structure on which the release layer was formed was exposed to an environment of 90 ° C. and 80% RH for 5 hours to chemically adsorb the release layer material on the surface of the mold structure (chemical bonding treatment). Thus, a mold structure of Example 1 was produced.

<Preparation of magnetic recording medium intermediate>
A soft magnetic layer, a first nonmagnetic alignment layer, a second nonmagnetic alignment layer, a magnetic recording layer, and a protective layer were formed in this order on a 2.5 inch glass substrate as follows. 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 sputtering. The lubricant layer on the protective layer was formed by a dip method.

First, CoZrNb was laminated as a soft magnetic layer material so as to have a thickness of 100 nm. Specifically, the glass substrate was placed facing the CoZrNb target, Ar gas was introduced so that the pressure became 0.6 Pa, and a soft magnetic layer was formed at DC 1,500 W.
Next, Pt was laminated as the first nonmagnetic alignment layer so as to have a thickness of 5 nm. Specifically, the soft magnetic layer formed on the substrate is placed opposite to the Pt target, Ar gas is introduced so that the pressure becomes 0.5 Pa, and the first nonmagnetic orientation is discharged by DC 1,000 W. Layers were deposited.
Next, Ru was laminated as the second nonmagnetic alignment layer so as to have a thickness of 10 nm. Specifically, the first nonmagnetic alignment layer formed on the substrate is placed facing the Ru target, Ar gas is introduced so that the pressure becomes 0.5 Pa, and discharge is performed at DC 1,000 W. A second nonmagnetic alignment layer was formed.
Next, CoPtCr—SiO ₂ was laminated as a magnetic recording layer to a thickness of 15 nm. Specifically, the second nonmagnetic alignment layer formed on the substrate is placed facing the CoPtCr—SiO ₂ target, Ar gas is introduced so that the pressure becomes 1.5 Pa, and discharge is performed at DC 1000 W. A magnetic recording layer was formed.
After the magnetic recording layer is formed, the magnetic recording layer formed on the substrate is placed facing the C target, Ar gas is introduced so that the pressure becomes 0.5 Pa, and the discharge is performed at DC 1,000 W. A 4 nm protective layer was deposited. Thus, a magnetic recording medium intermediate was produced. The coercive force of the obtained magnetic recording medium intermediate was 334 kA / m (4.2 kOe).

<Preparation of nanoimprint and discrete type perpendicular magnetic recording medium>
A photocurable acrylic imprint resist solution (manufactured by Toyo Gosei Co., Ltd .: PAK-01) was formed on the produced magnetic recording medium intermediate by a 100 nm spin coating method.
The above-mentioned mold structure was placed opposite to the obtained magnetic recording medium intermediate with a resist layer, and the magnetic recording medium intermediate was pressed at a pressure of 1 MPa for 5 seconds to transfer a pattern, and then 25 mJ / cm ² . The pattern was cured by irradiation with UV light for 10 seconds. Thereafter, the mold structure and the magnetic recording medium intermediate were peeled off to form a concavo-convex pattern on the resist layer on the magnetic recording medium intermediate.
Thereafter, selective etching is performed by Ar ion sputter etching (ICP type, Ar gas, 0.2 Pa, ICP / Bias = 750 W / 300 W) using the imprint resist layer 25 to which the pattern of the uneven portion 3 is transferred as a mask. A concavo-convex shape based on the pattern shape of the concavo-convex portion 3 formed on the imprint mold structure 1 is formed in the magnetic layer 50, a nonmagnetic material 70 (SiO ₂ is formed by a CVD method) is embedded in the concave portion, and the surface is After flattening (CMP treatment), a protective film was formed (a DLC protective layer was formed by a CVD method) to obtain the magnetic recording medium 100. Thus, the discrete type perpendicular magnetic recording medium of Example 1 was produced.

<< Evaluation of transferability >>
When the imprint resist layer formed on the surface of the substrate was transferred using the mold structure of Example 1 onto the imprint resist layer having a 50 nm & 50 nm line and space and a height of 50 nm, the remaining film of the imprint resist layer was formed. Eight points were evaluated every 45 ° at a distance of 30 mm from the center. The thickness of the remaining film was observed by a cross-sectional TEM image, and the variation (maximum value−minimum value) of the remaining film was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1.

[Evaluation criteria]
○: Variation amount is 40 nm or less.
X: The variation amount exceeds 40 nm.

<< Durability Evaluation >>
Using the mold structure of Example 1, the process of transferring the concavo-convex pattern onto the imprint resist layer formed on the surface of the substrate was performed 100 times, and after the process, cracks and microcracks were detected by the ultrasonic imaging method below. Evaluation was performed based on the evaluation criteria. The evaluation results are shown in Table 1.

[Evaluation criteria]
○: There are no cracks or microcracks.
X: There exist a crack and a microcrack.

<< Evaluation of servo characteristics >>
For the magnetic recording medium produced in the production of the magnetic recording medium described above, a magnetic head tester for hard disk equipped with a GMR head having a reproducing track width of 0.1 μm and a reproducing gap of 0.06 μm (BitFinder Model-YS manufactured by Aimes)
3300), the position error signal (PES) of the reproduction signal was measured and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria]
◎: Media with servo following and PES within ± 10% of track width ○: Media with servo following PES within ± 10% to ± 20% of track width ×: Servo following not possible Medium

(Examples 2 to 28)
<Production of mold structure>
In Example 1, except that the thickness (Dm), the surface area (S ₁ ), and the surface area (S ₂ ) of the concavo-convex pattern were changed as shown in Table 1, the same as in Example 1, Mold structures of Examples 2 to 28 were produced.

<Preparation of magnetic recording medium>
In Example 1, magnetic recording media of Examples 2 to 28 were produced in the same manner as in Example 1 except that the mold structure and the magnetic recording medium intermediate shown in Table 1 were used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced mold structures and magnetic recording medium intermediates of Examples 2 to 28 was evaluated. The evaluation results are shown in Table 1.

<< Durability Evaluation >>
In the same manner as in Example 1, durability of the produced mold structures of Examples 2 to 28 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of servo characteristics >>
In the same manner as in Example 1, the servo characteristics of the produced magnetic recording media of Examples 2 to 28 were evaluated. The evaluation results are shown in Table 1.

(Examples 29 and 30)
<Production of mold structure>
As shown in FIG. 4B, the conductive film 22 is formed on the surface of the master 11 having the concavo-convex shape produced in the same manner as in Example 1 by sputtering based on the concavo-convex pattern on the surface of the master 11. Thereafter, the master disk provided with the conductive film 22 is immersed in a Ni electroforming bath having the following composition, and is rotated at a rotational speed of 50 to 150 rpm. A board was produced. Thereafter, the Ni disc was peeled from the master disc, and the remaining resist film was removed and washed. In this way, a mold structure was obtained.
-Ni electroforming bath composition and temperature-
Nickel sulfamate ... 600g / L
Boric acid ... 40g / L
Surfactant (sodium lauryl sulfate) ... 0.15 g / L
PH = 4.0
Temperature = 55 ° C
Table 1 shows the thickness (Dm), surface area (S ₁ ), and surface area (S ₂ ) of the uneven pattern of the obtained mold structure.
When the Ni plate 23 is manufactured by forming the conductive film 22 to a predetermined thickness, the cross-sectional shape of the concave portion of the Ni plate 23 is transferred from the cross-sectional shape of the convex portion 3 shown in FIGS. The cross-sectional shape was performed.

<Preparation of magnetic recording medium>
An imprint resist solution made of PMMA resin was formed on the magnetic recording medium intermediate produced in the same manner as in Example 1 by a 100 nm spin coating method.
The above-described magnetic recording medium intermediate with a resist layer was placed with the above-mentioned mold structure made of Ni facing, and heated at 150 ° C. and pressurized at 3 MPa for 30 seconds to transfer the pattern, and then 60 The pattern was cured by cooling to ° C. Thereafter, the mold structure and the magnetic recording medium intermediate were peeled off to form a concavo-convex pattern on the resist layer on the magnetic recording medium intermediate.
Next, etching was performed using the formed uneven pattern as a mask to form an uneven shape on the magnetic recording layer. Thus, the perpendicular magnetic recording media of Examples 29 and 30 were produced.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced mold structures and magnetic recording medium intermediates of Examples 29 and 30 was evaluated. The evaluation results are shown in Table 1.

<< Durability Evaluation >>
In the same manner as in Example 1, the durability of the produced mold structures of Examples 29 and 30 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of servo characteristics >>
In the same manner as in Example 1, the recording / reproduction characteristics of the produced magnetic recording media of Examples 29 and 30 were evaluated. The evaluation results are shown in Table 1.

(Examples 31 and 32)
<Production of mold structure>
After the master 11 having the concavo-convex shape produced in the same manner as in Example 1 was placed with a thermoplastic resin made of PMMA facing and pressed at a pressure of 3 MPa for 30 seconds while being heated to 150 ° C., the pattern was transferred. The pattern was cured by cooling to 60 ° C. Then, the resin mold structure 1 which has uneven | corrugated shape was obtained by peeling with a mold structure.
Table 1 shows the thickness (Dm), surface area (S ₁ ), and surface area (S ₂ ) of the uneven pattern of the obtained mold structure.

<Preparation of magnetic recording medium>
In Example 1, the magnetic recording media of Examples 31 and 32 were produced in the same manner as in Example 1 except that the mold structure shown in Table 1 was used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced mold structures and magnetic recording medium intermediates of Examples 31 and 32 was evaluated. The evaluation results are shown in Table 1.

<< Durability Evaluation >>
In the same manner as in Example 1, the durability of the produced mold structures of Examples 31 and 32 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of servo characteristics >>
In the same manner as in Example 1, the recording / reproducing characteristics of the produced magnetic recording media of Examples 31 and 32 were evaluated. The evaluation results are shown in Table 1.

(Comparative Examples 1-3)
<Production of mold structure>
In Example 1, except that the thickness (Dm), the surface area (S ₁ ), and the surface area (S ₂ ) of the concavo-convex pattern were changed as shown in Table 1, the same as in Example 1, Mold structures of Comparative Examples 1 to 3 were produced.

<Preparation of magnetic recording medium>
In Example 1, the magnetic recording media of Comparative Examples 1 to 3 were produced in the same manner as in Example 1 except that the mold structure shown in Table 1 was used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced mold structures of Comparative Examples 1 to 3 and the magnetic recording medium intermediate was evaluated. The evaluation results are shown in Table 1.

<< Durability Evaluation >>
In the same manner as in Example 1, the durability of the fabricated mold structures of Comparative Examples 1 to 3 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of recording / reproduction characteristics >>
In the same manner as in Example 1, the recording / reproducing characteristics of the produced magnetic recording media of Comparative Examples 1 to 3 were evaluated. The evaluation results are shown in Table 1.

As shown in Table 1, Examples 1-32 satisfying the above mathematical formula (1) specify an appropriate value of the thickness of the mold structure relative to Comparative Examples 1-3 not satisfying the above mathematical formula (1). In addition, since the handling property is improved, the durability and the transfer property to the substrate are high, and it is possible to provide a mold structure that transfers and forms a high-quality pattern on a discrete track medium or a patterned medium.
In addition, Examples 1, 4 to 25, and 29 to 32 satisfying the above formulas (1) to (2) are more excellent in durability than Examples 2, 3, and 26 to 28 satisfying only the expression (1). A larger number of magnetic recording media could be produced from one mold structure.

  On the other hand, Comparative Example 1 was inferior in both transferability and durability because the thickness of the mold structure was thin and shape stability could not be ensured. In Comparative Examples 2 to 3, since the mold structure was thick and strong, the durability was good, but the transferability was inferior.

  According to the mold structure of the present invention, the fine pattern formed on the mold structure can efficiently enter the resist on the substrate, and the pattern can be formed on the substrate with a high yield. It is suitable for production and production of patterned media.

FIG. 1 is a partial perspective view showing a configuration in an embodiment of a mold structure according to the present invention. FIG. 2A is a cross-sectional view illustrating an example of a method for manufacturing a mold structure in Examples 1 to 15. FIG. 2B is a cross-sectional view illustrating an example of a method for manufacturing a mold structure in Examples 1 to 15. FIG. 3 is a cross-sectional view showing a manufacturing method for manufacturing a magnetic recording medium using the mold structure according to the present invention. 4A is a cross-sectional view illustrating an example of a method for producing a mold structure in Example 16. FIG. 4B is a cross-sectional view illustrating an example of a method for manufacturing a mold structure in Example 16. FIG. 5A is a cross-sectional view illustrating an example of a method for producing a mold structure in Example 17. FIG. FIG. 5B is a cross-sectional view illustrating an example of a method for manufacturing a mold structure in Example 17.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold structure 2 Substrate 3 Concave and convex part 3a Convex part 3b Concave part 24 Imprint resist layer 40 Substrate of magnetic recording medium 50 Magnetic layer 100 Magnetic recording medium

Claims (7)

A concavo-convex pattern is formed on the surface of a substrate having a thickness of 0.3 mm to 2.0 mm and an imprint resist layer formed on the surface, and the imprint pattern is made to face the imprint resist layer. A mold structure for transferring the concavo-convex pattern to a resist layer, the thickness Dm (mm) of the mold structure, the thickness Ds (mm) of the substrate, and the area S ₁ (mm ² ) of the mold structure Satisfies the following mathematical formula (1).
0.5 ≦ (Dm / Ds) × S ₁ ^1/2 ≦ 100... Equation (1) The thickness Dm of the mold structure, the thickness Ds of the substrate, the area S ₁ (mm ² ) of the mold structure, and the surface area S ₂ (mm ² ) of the concavo-convex pattern satisfy the following formula (2): The mold structure as described.
0.01 ≦ (Dm / Ds) × (S ₂ / S ₁ ) ^1/2 ≦ 1... Equation (2)   The mold structure according to claim 1, wherein the thickness is 0.01 mm or more and less than 0.5 mm.   The mold structure according to any one of claims 1 to 3, comprising any one of quartz, nickel, and resin. For a substrate having an imprint resist layer formed on the surface, the mold structure having a concavo-convex pattern formed on the surface is transferred to the imprint resist with the concavo-convex pattern facing the imprint resist layer. In the imprint method including at least a transfer step, the thickness Dm (mm) of the mold structure, the thickness Ds (mm) of the substrate, and the area S ₁ (mm ² ) of the mold structure are as follows: An imprint method characterized by satisfying Equation (1).
0.5 ≦ (Dm / Ds) × S ₁ ^1/2 ≦ 100... Equation (1) A transfer step of transferring the concavo-convex pattern formed on the mold structure by pressing the mold structure according to any one of claims 1 to 4 against an imprint resist layer formed on a substrate of a magnetic recording medium. ,
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;
And a non-magnetic pattern portion forming step of embedding a non-magnetic material in the concave portion formed on the magnetic layer.   A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to claim 6.