JP2009048752A - Imprint mold structure, and imprinting method using the same, magnetic recording medium, and method for manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imprint mold structure which has excellent transferability to an imprint resist and excellent separation performance from the imprint resist, and transfers and forms a high quality pattern on a discrete track medium or a patterned medium by an effect of the contraction of an imprint resist composition in volume after the imprint resist has been cured is reduced, to provide an imprinting method, to provide a method for manufacturing a magnetic recording medium, and to provide the magnetic recording medium. <P>SOLUTION: In the imprint mold structure including a disc-shaped substrate and a concavo-convex pattern having a plurality of convex portions formed on one surface of the substrate on the basis of the surface and used for transferring the concavo-convex pattern to an imprint resist layer formed on the other substrate by making the concavo-convex pattern face the imprint resist layer, the cross-sectional shape of the concavo-convex pattern in the direction in which the convex portion extends satisfies the following three mathematical expressions: a mathematical expression (1) 40°≤θ<90°(θ denotes an angle formed by the surface and the side wall of the convex portion), a mathematical expression (2) SRas>SRab (SRas denotes the surface average roughness of the side wall and SRab denotes the surface average roughness of the bottom of a concave part), a mathematical expression (3) LRah>LRav (LRah denotes the line average roughness of the side wall in a direction in which the convex portion extends and LRav denotes the line average roughness of the side wall in a direction along the side wall). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

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

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

When manufacturing the discrete track media or the patterned media, a resist pattern forming mold (also referred to as “stamper”) is used to form a resist layer formed on the surface of the magnetic recording medium. An imprinting method (imprint process) for transferring a desired pattern is used (see Patent Document 4).
Specifically, in this imprinting method, a thermosetting resin or a photocurable resin is applied to a substrate to be processed, and the applied resin is processed into a desired shape. The mold is adhered and pressed, the resin is cured by heating or light irradiation, and the mold is peeled off to form a pattern corresponding to the pattern formed on the mold, and this pattern is used as a mask. This is a method for obtaining a desired magnetic recording medium by performing patterning by dry or wet etching.
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. In addition, it is necessary to write 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 section is composed of four main patterns such as preamble, servo timing mark, address (sector, cylinder), burst, etc., and the address (sector, cylinder) and burst pattern are mixed with coarse and dense signals. 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 number of transfer processes from the viewpoint of cost reduction, at least several hundred to several tens of thousands of transfer durability is required for the imprint mold structure.

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

As described above, when an information recording medium such as a hard disk or an optical disk is obtained by using the imprint process, it is necessary to obtain a very fine and identical mask pattern on the entire surface of the substrate. In the media, a pattern with a high aspect ratio is required in order to obtain a margin in the etching process in the next step, which is an ultrafine pattern.
Therefore, in the imprint process, in order to realize the formation of such a fine pattern, the concavo-convex pattern formed on the imprint mold structure is transferred to the imprint resist with high accuracy and transferred. It was necessary to satisfy conflicting manufacturing conditions such as peeling the imprint mold structure from the imprint resist without destroying the uneven pattern.

However, in an imprint process using an imprint resist composition containing a photo-curable resin such as ultraviolet rays, the imprint mold structure in the subsequent etching process due to volume shrinkage during curing of the imprint resist composition. There is a risk that the uneven shape formed on the surface cannot be accurately reflected.
In addition, in order to suppress volume shrinkage at the time of curing of the imprint resist composition, there is also a method of increasing the roughness of the surface of the side wall of the concavo-convex pattern formed on the imprint mold structure to have an anchor effect. Although it can be considered, it is difficult to peel off the imprint mold structure after curing from the imprint resist, which causes damage to the transferred concavo-convex pattern.
Note that Patent Document 6 discloses an imprint mold structure in which a wall angle is defined as 30 ° to 80 °, but no countermeasure is taken against volume shrinkage during curing of the imprint resist composition. There was room for improvement.

  Therefore, the transfer property to the imprint resist and the peelability from the imprint resist are high, and the effect of volume shrinkage after curing of the imprint resist is reduced to transfer high-quality patterns to discrete track media and patterned media. The imprint mold structure to be formed and the related technology have not been realized yet, and the provision of the structure is desired.

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 2006-164393 A S. Y. Chou, et al. , Appl. Phys. Lett. , Vol. 67, 3314, 1995

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. In other words, the present invention has high transferability to the imprint resist and peelability from the imprint resist, and reduces the influence of volume shrinkage after the imprint resist is cured, so that it has high quality for discrete track media and patterned media. It is an object of the present invention to provide an imprint mold structure for imprinting a simple pattern, an imprint method, a method for manufacturing a magnetic recording medium, and a magnetic recording medium.

Means for solving the problems are as follows. That is,
<1> It has a concave and convex portion formed by arranging a plurality of convex portions on one surface of the disc-shaped substrate and the surface on the basis of the surface, on another substrate An imprint mold structure used for transferring a concavo-convex pattern based on the concavo-convex portion to the imprint resist layer with the concavo-convex portion opposed to the formed imprint resist layer, the convex portion The imprint mold structure is characterized in that a cross-sectional shape of the concavo-convex portion in a direction in which the slabs are arranged satisfies the following mathematical formulas (1) to (3).
40 ° ≦ θ <90 ° ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (1)
SRas> SRab ... Formula (2)
LRah> LRav ........................... Formula (3)
However, in the formula (1), θ (°) represents a wall angle formed by the surface and the side wall portion of the convex portion, and in the formula (2), SRas is a surface average roughness of the side wall portion. SRab represents the surface average roughness of the bottom of the concave portion, and in the above formula (3), LRah represents the line average roughness of the side wall portion in the direction in which the convex portion is extended, and LRav Represents the line average roughness of the side wall in the direction along the side wall.
In the mold structure for imprints according to <1>, the surface average roughness SRas of the side wall portion is larger than the surface average roughness SRab of the bottom portion of the recess, so that the curing performed after transfer is performed. In the step, the imprint resist layer closely adhered to the side wall portion can be held by an anchor effect, and volume shrinkage of the imprint resist layer can be suppressed.
Further, the wall angle θ formed by the surface and the side wall portion of the convex portion is less than 90 °, and the line average roughness LRah of the side wall portion in the direction in which the convex portion is extended is By being larger than the line average roughness LRav of the side wall portion in the direction along, the cross-sectional shape of the convex portion in the arrangement direction of the convex portion of the imprint mold structure has a tapered shape, Since the direction along the side wall portion is a direction in which the imprint mold is separated from the imprint resist layer, the peelability of the imprint mold structure with respect to the imprint resist layer is improved.
<2> The concavo-convex portion is a first concavo-convex portion in which a plurality of convex portions are formed concentrically with respect to a substantially central portion of the substrate, and a plurality of convex portions are radially formed with reference to the substantially central portion of the substrate It is an imprint mold structure as described in said <1> which has at least any one of the 2nd uneven | corrugated | grooved part formed.
<3> The surface average roughness SRas of the side wall portion of the convex portion and the surface average roughness SRab of the bottom portion are both 0.1 nm or more and 10 nm or less. This is a mold structure for printing.
<4> The line average roughness LRah of the side wall part in the direction in which the convex part is extended and the line average roughness LRav of the side wall part in the direction along the side wall part are both 0.1 nm or more and 10 nm or less. The imprint mold structure according to any one of <1> to <3>.
<5> The imprint mold structure according to any one of <1> to <4>, which is made of any material of quartz, nickel, and resin.
<6> The imprint mold structure according to any one of <1> to <5> is pressed against an imprint resist layer made of an imprint resist composition formed on a substrate of a magnetic recording medium. It is an imprint method characterized by including at least the transfer process which transfers the uneven | corrugated pattern based on the uneven | corrugated | grooved part formed in the said mold structure for imprints.
<7> The imprint mold structure according to any one of <1> to <5> is pressed against an imprint resist layer formed on a substrate of a magnetic recording medium. A transfer process for transferring the concavo-convex pattern formed on,
Using the imprint resist layer to which the concavo-convex pattern is transferred as a mask, the magnetic layer formed on the surface of the substrate of the magnetic recording medium is etched to form a magnetic pattern portion based on the concavo-convex pattern in the magnetic layer. A magnetic pattern portion forming step;
A non-magnetic pattern part forming step of embedding a non-magnetic material in the recess formed on the magnetic layer;
A method for manufacturing a magnetic recording medium, comprising:
<8> A magnetic recording medium produced by the method for producing a magnetic recording medium according to <7>.

  According to the present invention, the transfer property to the imprint resist and the releasability from the imprint resist are high, and the influence of volume shrinkage after curing of the imprint resist is reduced, so that the quality of the discrete track media and patterned media is high. Imprint mold structure for transferring pattern, imprint method for improving transfer accuracy by using the imprint mold structure, and magnetic recording medium having improved recording characteristics and reproduction characteristics, And a manufacturing method thereof.

Hereinafter, the DTM imprint mold structure in the present invention will be described with reference to the drawings.
(Imprint mold structure)
FIG. 1 is a partial cross-sectional perspective view showing a configuration in an embodiment of an imprint mold structure according to the present invention.
As shown in FIG. 1, the imprint mold structure 1 of the present embodiment has a plurality of protrusions on one surface 2 a (hereinafter, also referred to as “reference surface 2 a”) of a disk-shaped substrate 2. The parts 4 are formed concentrically at a predetermined interval, and further include other members as necessary.
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 signal for tracking servo control, and is mainly concentrated in, 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.
In the description of this embodiment, the convex portion 4 and the concave portion 5 formed between the plurality of convex portions 4 may be referred to as the concave and convex portion 3.
Specifically, the convex portion 4 includes a side wall portion 4a that is an inclined surface inclined in the radial direction of the substrate 2 at a predetermined wall angle with respect to the substrate 2, and a side wall portion 4a that is inclined opposite to the surface 2a. And a top portion 4b connected substantially in parallel. Therefore, the cross-sectional shape of the convex portion 4 in the radial direction of the concentric circles (the direction in which the convex portions 4 are arranged) is preferably a trapezoid and is an isosceles trapezoid.
Moreover, the cross-sectional shape of the said convex part 4 can select arbitrary shapes by controlling the etching process mentioned later according to the objective.
Moreover, the recessed part 5 is comprised by the two side wall parts 4a and 4a inclined so that it might mutually space apart, and the surface 2a.
Hereinafter, in the description of the present embodiment, “cross section (shape)” refers to a cross section (shape) in the radial direction of the concentric circle (direction in which the convex portions 4 are arranged) unless otherwise specified.
Moreover, it is preferable that the thickness of the board | substrate 2 is 0.01 mm or more and less than 1.5 mm.
Moreover, the height (depth of the recessed part 5) H of the convex part 4 of the board | substrate 2 has the preferable range of 10-800 nm, and its 30-300 nm is more preferable.

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.

-Other components-
The other members are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose. For example, the other members are formed in layers on the substrate 2 and are peeled off from the imprint resist layer. Examples include a mold surface layer having a function.

In the imprint mold structure 1 of the present invention, the wall angle formed between the surface 2a and the side wall portion 4a of the convex portion 4 is θ (°), the surface average roughness of the side wall portion 4a is SRas, and the concave portion 5 The surface average roughness of the bottom (surface 2a sandwiched between the side walls 4a, 4a constituting the recess 5) is SRab, and the line average roughness of the side wall 4a in the direction in which the protrusion 4 extends is LRah, When the line average roughness of the side wall portion 4a in the direction in which the convex portions 4 are arranged is LRav, it is preferable that the following mathematical formulas (1) to (3) are satisfied.
40 ° ≦ θ <90 ° ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (1)
SRas> SRab ... Formula (2)
LRah> LRav ........................... Formula (3)

Here, the wall angle θ formed by the surface 2a and the side wall portion 4a of the convex portion 4 is different from one side wall portion 4a constituting the convex portion 4 and one side wall portion 4a among the other side wall portions. The angle formed with the surface 2a on the side inclined to the side wall portion 4a.
In the above formula (1), if θ is less than 40 °, adjacent patterns cannot be made sufficiently dense, and patterning of the magnetic layer becomes sparse, so that the purpose of improving the recording density cannot be achieved. . Further, when the θ is 90 ° or more, when the imprint resist is cured and then peeled, the uneven portion formed on the imprint mold structure and the imprint resist formed by the uneven portion There is a problem that the upper uneven pattern interferes and cannot be peeled off.

Further, the surface average roughness (SRas) of the side wall 4a is obtained by measuring the surface average roughness of the four side walls constituting the two different convex portions 4 and 4 by the AFM (atomic force microscope) and the probe 4a. It is calculated | required by measuring the atomic force which acts between these, and averaging the measured value.
The surface average roughness (SRas) of the side wall part 4a is more preferably 0.1 nm to 10 nm.

Further, the surface average roughness (SRab) of the bottom of the concave portion 5 is obtained by using the AFM (atomic force microscope) to calculate the surface average roughness of two bottom portions constituting two different concave portions 5 and 5. It is obtained by measuring the interatomic force acting between them and averaging the measured values.
The surface average roughness (SRab) of the bottom of the recess 5 is more preferably 0.1 nm to 10 nm.
In the above formula (2), if SRas ≦ SRab, an anchor effect occurs in the height direction due to volume shrinkage that occurs when the imprint resist is cured, so that the most important pattern accuracy in the width direction is degraded. As a result, there is a problem that the pattern area of the magnetic layer becomes small.

Moreover, the line average roughness (LRah) of the side wall part 4a in the direction in which the convex part 4 extends is specifically the average height of the convex part 4 with respect to the reference surface 2a, as shown in FIG. Is the line average roughness at the intersection line L1 between the plane S1 and the side wall portion 4a that are substantially parallel with a half (H / 2) interval, and from the measurement data of the plane average surface roughness of the side wall surface, the intersection line The line average roughness can be obtained by extracting the data at the location.
The line average roughness (LRah) of the side wall part 4a in the direction in which the convex part 4 is extended is more preferably 0.1 nm to 10 nm.

Further, the line average roughness (LRav) of the side wall part 4a in the direction along the side wall part 4a specifically includes the arrangement direction of the convex parts 4 (radial direction in the drawing) as shown in FIG. , The line average roughness at the intersection line L2 between the surface S2 orthogonal to the reference plane 2a and the side wall 4a, and by extracting the data of the intersection line from the side wall surface roughness measurement data, The line average roughness can be determined.
The line average roughness (LRav) of the side wall part 4a in the direction along the side wall part 4a is more preferably 0.1 nm to 10 nm.
In the above formula (3), when LRah ≦ LRav, when the imprint resist composition is cured and then peeled, the imprint resist layer becomes rough on the side wall of the imprint mold structure. There is a problem that the resist pattern peels off.

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

(Method for producing imprint mold structure)
Hereinafter, a method for producing an imprint mold structure 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 an imprint mold structure. 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 (photoresist layer forming step).
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 (drawing step).
Here, in the drawing step, by selecting drawing conditions (specifically, beam energy, incident angle, beam intensity distribution, stage movement accuracy) within a suitable range, the surface roughness of the side wall of the recess is reduced. The line average roughness of the side wall in the direction in which the convex portion extends is larger than the line average roughness of the side wall in the direction along the side wall so as to be larger than the surface roughness of the bottom. Form to be large.
Thereafter, a predetermined pattern on the entire surface of the photoresist, for example, a data track pattern composed of a substantially concentric convex pattern, a servo pattern composed of a plurality of types of convex patterns having different convex areas, and the data track pattern and the servo pattern A buffer pattern composed of substantially radial convex patterns connected in the radial direction is exposed (exposure process).
Thereafter, the photoresist layer 21 is developed, the exposed portion is removed, selective etching such as RIE (reactive ion etching) is performed using the pattern of the removed photoresist layer 21 as a mask (etching step), and the substrate An uneven pattern is formed on 10. Next, the remaining resist layer 21 is removed to obtain a master 11 having an uneven shape.
Specifically, by using an electron beam whose beam intensity increases toward the center of the beam, there is no resist residue at the post-development beam drawing location, and the boundary line roughness (LER) with the resist remainder is within 2 nm. Can do.
Here, in the etching step, the angle of θ is set to 40 ° or more by selecting an etching gas species, a mixing ratio thereof, and etching conditions (specifically, process pressure, bias power, etc.) within a suitable range. , In a range of less than 90 °.
Specifically, a rare gas, hydrogen gas, oxygen gas or the like is introduced into the CF-based gas at a pressure of 0.1 to 10.0 Pa, power of 100 to 1,000 W for the plasma source, and power of 20 to 400 W for the substrate side. . In order to make the wall angle in the vertical direction, a low pressure is preferable, and it can be obtained by using a large amount of a gas that is physically sputter-etched without using a chemical reaction such as a rare gas and increasing the input power to the substrate side.

<< Preparation of mold structure for imprint >>
Next, as shown in FIG. 2B, with respect to 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 convex portions formed on the master 11 is transferred to the imprint resist layer 24 (transfer process).

<< 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”). Is a layer formed by applying to the substrate of the magnetic recording medium.
The thickness of the imprint resist layer 24 is preferably 10 to 200%, more preferably 20 to 150%, with respect to the height of the convex portion. A specific thickness is preferably 10 to 100 nm.
The thickness of the imprint resist layer 24 can be measured, for example, by optical measurement using an ellipsometer or a contact measurement method such as a stylus type step type, an atomic force microscope (AFM).
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 30 is not particularly limited as long as it is a material having optical transparency and functioning as the imprint mold structure 1, and is appropriately selected according to the purpose. Examples thereof include quartz (SiO ₂ ) and organic resins (PET, PEN, polycarbonate, low melting point fluororesin, PMMA) and the like.
Further, the “having light transmissivity” specifically means that the light is emitted from the other surface of the substrate to be processed 30 so as to be emitted from the one surface of the substrate to be processed 30 on which the imprint resist layer 24 is formed. It means that the imprint resist solution is sufficiently cured when light is incident, and at least the light transmittance from the other surface to the one surface is 50% or more. To do.
Further, “having the strength to function as an imprint mold structure” means that the average surface pressure is 4 kgf / cm ² with respect to the imprint resist layer formed on the substrate of the magnetic recording medium. It means the strength that does not break in a peelable manner even when pressed or pressed.

<< Curing process >>
Thereafter, the imprint resist layer 24 is irradiated with light such as ultraviolet rays to cure the transferred pattern.

<< Pattern formation process >>
After that, selective etching such as RIE is performed using the transferred pattern as a mask to obtain an imprint mold structure 1 having an uneven shape as 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>
Hereinafter, a magnetic recording medium such as a discrete track medium and a patterned medium manufactured using the imprint mold structure according to the present invention will be described with reference to the drawings. However, the magnetic recording medium according to the present invention may be manufactured by a manufacturing method other than the following manufacturing method as long as it is manufactured using the imprint mold structure according to the present invention.

[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 step 1 is transferred to the resist layer 24.

Here, the imprint resist layer 25 in the production of the magnetic recording medium is the same imprint as the imprint resist layer 24 in the production of the imprint mold structure as long as the transfer accuracy in the transfer process in the production of the magnetic recording medium is not impaired. A resist composition may be employed.
Hereinafter, unless otherwise specified, the imprint resist layer and the imprint resist composition refer to the imprint resist layer 25 in the production of the magnetic recording medium and the imprint resist composition that forms the imprint resist layer 25. And

[Curing process]
-Curing by light irradiation-
When the imprint resist composition forming the imprint resist layer 25 contains a photocurable resin, the imprint resist layer 25 is irradiated with an electron beam such as ultraviolet rays through the imprint mold structure 1 having transparency. Then, the imprint resist layer 25 is cured.

―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 for forming the imprint resist layer 25 contains a thermosetting resin, when the imprint mold structure 1 is pressed against the imprint resist layer 25, the system is subjected to glass transition of the resist solution. The imprint resist layer 25 is cured by maintaining the point (Tg) and lowering the glass transition point of the resist solution after the transfer.

  Here, the imprint resist corresponding to the width of the concave portion of the imprint mold structure when the uneven pattern was transferred to the imprint resist layer using the prepared imprint mold structure and the curing process was performed. The width of the convex portion (width of the convex portion of the imprint resist / width of the concave portion of the imprint mold structure) is preferably within ± 5%.

[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 type.
drift type and the like.
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.

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

(Example 1)
<Preparation of imprint mold structure>
<< Formation of photoresist layer >>
As shown in FIG. 2A, an electron beam resist was applied to a thickness of 100 nm on a disk-shaped 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 of 90 nm at the innermost circumference, 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, as shown in FIG. 2B, 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. The UV nanoimprint, after pattern transfer at a pressure of 1 MPa 5 seconds pressurized and allowed to cure the pattern of UV light of 25 mJ / cm ² was irradiated 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: 1: 1 of CF gas and Ar gas, trace amount of hydrogen gas 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 was performed so that the cross-sectional shape of the concave portion 5 of the imprint mold structure 1 having an uneven shape was a cross-sectional shape obtained by transferring the cross-sectional shape of the convex portion 4 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.

  For the following measurements, an atomic force microscope (SPA-500, manufactured by Seiko Instruments Inc.) was used with respect to the line shape pattern of the data portion at a radial position of 20 mm and in four angular directions (every 90 °). The average of 5 points measured in each field of view is shown.

<< Measurement of Wall Angle θ of Side Wall >>
After cutting out a cross-sectional sample in the radial direction at the sample position, an SEM image was taken. Measurements were made at 5 points and 4 azimuth directions in each field of view to obtain an average value.

<< Measurement of surface average roughness (SRas, SRab) of side wall and recess >>
With respect to the sample position, a 500 nm square area is measured by AFM, and the surface average roughness is obtained from the data for each of the side wall portion and the concave portion area. At this time, the side walls constituting the two different recesses and the bottom surface area of the recess are measured and obtained as an average value.

<< Measurement of Line Average Roughness (LRah, LRav) of Side Walls in Direction of Protruding Extension and Direction along Side Walls >>
In the AFM data, data of a straight line portion along each direction can be extracted to obtain a line average roughness.

<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 is 0.5 Pa, and 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 imprint resist solution (fluorine resin resist: NIF-1 manufactured by Asahi Glass Co., Ltd.) 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 >>
Using the produced imprint mold structure, a concavo-convex pattern is transferred to the imprint resist layer, and the imprint resist convex portion corresponding to the width of the concave portion of the imprint mold structure when the curing process is performed. The width (width of the convex portion of the imprint resist / width of the concave portion of the imprint mold structure) was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria]
○: The width of the convex portion of the imprint resist corresponding to the width of the concave portion of the imprint mold structure is within ± 5% Δ: The height of the convex portion of the imprint resist corresponding to the width of the concave portion of the mold structure for imprint Width: ± 5% or more and 10% or less x: The width of the convex portion of the imprint resist corresponding to the width of the concave portion of the imprint mold structure exceeds ± 10%

<< Evaluation of peelability >>
After performing the transfer process, evaluate the number of concavo-convex patterns of the imprint resist that were missing or defective with respect to the peelability when the imprint mold structure was peeled off from the imprint resist layer based on the following evaluation criteria. did. The results are shown in Table 1.

[Evaluation criteria]
◯: There were no defects or defects among the ten concavo-convex patterns (books) of the imprint resist. Δ: One of the concavo-convex patterns (books) of the imprint resist was missing or defective. : Out of 10 uneven patterns (books) of imprint resist, 2 (books) were missing or defective.

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

[Evaluation criteria]
◎: Servo following and PES within ± 10% of track width ○: Servo following was possible, but PES was ± 10% or more ± 20% or less of track width ×: Servo following was not possible

(Examples 2-11, Comparative Examples 1-6)
<Preparation of imprint mold structure>
In Example 1, except that the wall angle θ (°), SRas, SRab, LRah, and LRav of the side wall portion of the imprint mold structure was changed as shown in Table 1, the same as in Example 1, The imprint mold structures of Examples 2 to 11 and Comparative Examples 1 to 6 were produced.

<< Measurement of Wall Angle θ of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured wall angle (theta) (degree) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRas) of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the surface average roughness (SRas) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRab) at Bottom of Recess >>
About the produced imprint mold structure, the surface average roughness (SRab) of the bottom of the recess was measured in the same manner as in Example 1. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRah) of Side Wall Part in Direction of Protruding Part >>>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRah) of the side wall part in the direction where the convex part was extended. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRav) of Side Wall Part in Direction along the Side Wall Part >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRav) of the side wall part in the direction along the said side wall part. The results are shown in Table 1.

<Imprint resist composition>
The same composition as in Example 1 was used as the imprint resist composition.

<Preparation of magnetic recording medium>
In Example 1, magnetic recording media of Examples 2 to 11 and Comparative Examples 1 to 6 were produced in the same manner as in Example 1 except that the imprint mold structure in each example was used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced imprint mold structures of Examples 2 to 11 and Comparative Examples 1 to 6 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of peelability >>
In the same manner as in Example 1, the peelability of the produced imprint mold structures of Examples 2 to 11 and Comparative Examples 1 to 6 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 magnetic recording media of Examples 2 to 11 and Comparative Examples 1 to 6 were evaluated. The evaluation results are shown in Table 1.

Example 12
<Preparation of imprint 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 wall angle θ (°), SRas, SRab, LRah, and LRav of the side wall portion of the obtained imprint mold structure 1.

<< Measurement of Wall Angle θ of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured wall angle (theta) (degree) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRas) of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the surface average roughness (SRas) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRab) at Bottom of Recess >>
About the produced imprint mold structure, the surface average roughness (SRab) of the bottom of the recess was measured in the same manner as in Example 1. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRah) of Side Wall Part in Direction of Protruding Part >>>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRah) of the side wall part in the direction where the convex part was extended. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRav) of Side Wall Part in Direction along the Side Wall Part >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRav) of the side wall part in the direction along the said side wall part. The results are shown in Table 1.

<Preparation of imprint resist composition>
As the imprint resist composition of this example, a thermoplastic novolak resin (viscosity: 30 mPa · s) was used.

<Preparation of magnetic recording medium>
A timing recording medium intermediate was prepared in the same manner as in Example 1.
The imprint resist composition having a thickness of 100 nm was formed on the magnetic recording medium intermediate. 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 medium of Example 12 was produced.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced imprint mold structure of Example 12 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of peelability >>
In the same manner as in Example 1, the peelability of the produced imprint mold structure of Example 12 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 medium of Example 12 were evaluated. The evaluation results are shown in Table 1.

(Example 13)
A thermoplastic resin made of PMMA was placed opposite to the master 11 having the concavo-convex shape produced in the same manner as in Example 1, and the pattern was transferred by applying pressure at 3 MPa for 30 seconds while being heated to 150 ° C. Thereafter, 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.

<< Measurement of Wall Angle θ of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured wall angle (theta) (degree) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRas) of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the surface average roughness (SRas) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRab) at Bottom of Recess >>
About the produced imprint mold structure, the surface average roughness (SRab) of the bottom of the recess was measured in the same manner as in Example 1. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRah) of Side Wall Part in Direction of Protruding Part >>>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRah) of the side wall part in the direction where the convex part was extended. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRav) of Side Wall Part in Direction along the Side Wall Part >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRav) of the side wall part in the direction along the said side wall part. The results are shown in Table 1.

<Imprint resist composition>
The same composition as in Example 1 was used as the imprint resist composition.

<Preparation of magnetic recording medium>
In Example 1, the magnetic recording medium of Example 13 was produced in the same manner as in Example 1 except that the imprint mold structure produced above was used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced imprint mold structure of Example 13 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of peelability >>
In the same manner as in Example 1, the peelability of the produced imprint mold structure of Example 13 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 manufactured magnetic recording medium of Example 13 were evaluated. The evaluation results are shown in Table 1.

(Example 14)
A mold structure 1 was obtained in the same manner as in Example 1.

<< Measurement of Wall Angle θ of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured wall angle (theta) (degree) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRas) of Side Wall >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the surface average roughness (SRas) of the side wall part. The results are shown in Table 1.

<< Measurement of Surface Average Roughness (SRab) at Bottom of Recess >>
About the produced imprint mold structure, the surface average roughness (SRab) of the bottom of the recess was measured in the same manner as in Example 1. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRah) of Side Wall Part in Direction of Protruding Part >>>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRah) of the side wall part in the direction where the convex part was extended. The results are shown in Table 1.

<< Measurement of Line Average Roughness (LRav) of Side Wall Part in Direction along the Side Wall Part >>
About the produced imprint mold structure, it carried out similarly to Example 1, and measured the line average roughness (LRav) of the side wall part in the direction along the said side wall part. The results are shown in Table 1.

<Imprint resist composition>
The same composition as in Example 1 was used as the imprint resist composition.

<Preparation of magnetic recording medium>
In Example 12, a magnetic recording medium of Example 14 was produced in the same manner as in Example 12 except that the imprint mold structure produced above was used.

<< Evaluation of transferability >>
In the same manner as in Example 1, the transferability of the produced imprint mold structure of Example 14 was evaluated. The evaluation results are shown in Table 1.

<< Evaluation of peelability >>
In the same manner as in Example 1, the peelability of the produced imprint mold structure of Example 14 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 manufactured magnetic recording medium of Example 14 were evaluated. The evaluation results are shown in Table 1.

As shown in Table 1, according to Examples 1 to 14 that satisfy the above mathematical formulas (1) to (3), transferability to Comparative Examples 1 to 6 that do not satisfy the above mathematical expressions (1) to (3). It was possible to provide a mold structure for imprinting that had high releasability and good releasability.
Moreover, the comparative examples 1-6 which do not satisfy | fill said numerical formula (1)-(3) by using the mold structure for imprint produced in Examples 1-14 which satisfy | fill said numerical formula (1)-(3). As a result, a magnetic recording medium with better servo characteristics could be provided.
In addition, Examples 1 to 8 and 10 in which SRas and SRab are 0.1 nm to 10 nm provide an imprint mold structure excellent in peelability and a magnetic recording medium excellent in recording / reproducing characteristics. I was able to.
Furthermore, Examples 1 to 6, 8, 9, and 12 to 14 in which SRas, SRab, LRah, and LRav are 0.1 nm to 10 nm can provide a magnetic recording medium excellent in recording and reproducing characteristics. .

On the other hand, in Comparative Examples 1 and 2, the line average roughness (LRah) of the side wall in the direction in which the convex portion is extended rather than the line average roughness (LRav) of the side wall in the direction along the side wall. Since the surface average roughness (SRas) of the side wall portion is larger than the surface average roughness (SRab) of the bottom portion of the concave portion, the transferability was good. Since the wall angle θ formed between the surface of the substrate of the mold structure and the side wall portion of the convex portion is 90 ° or more, the peelability was inferior.
Further, in Comparative Example 3, the line average roughness (LRah) of the side wall in the direction in which the convex portion is extended is larger than the line average roughness (LRav) of the side wall in the direction along the side wall. Therefore, the releasability was good, but the surface average roughness (SRab) of the bottom of the concave portion is larger than the surface average roughness (SRas) of the side wall, so that the transferability is inferior. It was.
In Comparative Example 4, the wall angle θ formed by the surface of the substrate of the imprint mold structure and the side wall portion of the convex portion is 40 ° or more and less than 90 °, and the surface average roughness ( Since the surface average roughness (SRab) of the bottom of the concave portion is larger than SRas), the transferability was good, but the line average roughness (LRav) of the side wall in the direction along the side wall. ) Is larger than the line average roughness (LRah) of the side wall portion in the direction in which the convex portion is extended, and therefore the peelability was inferior.
Further, in Comparative Example 5, the surface average roughness (SRab) of the bottom of the concave portion is larger than the surface average roughness (SRas) of the side wall portion, and the side wall portion in the direction in which the convex portion is extended. Since the line average roughness (LRah) is larger than the line average roughness (LRav) of the side wall part in the direction along the side wall part, the peelability was good, but the mold structure for imprinting Since the wall angle θ formed by the surface of the body substrate and the side wall portion of the convex portion is less than 45 °, the transferability was inferior.
In Comparative Example 6, the wall angle θ formed by the surface of the substrate of the imprint mold structure and the side wall portion of the convex portion is less than 45 °, and the surface average roughness (SRab) of the bottom portion of the concave portion is The surface average roughness (SRas) of the side wall portion is greater than the surface average roughness (SRas), and the line average roughness (LRav) of the side wall portion in the direction along the side wall portion is the side wall in the direction in which the convex portion is extended. Since it was larger than the line average roughness (LRah) of the part, the transferability and peelability were inferior.

  In the imprint mold structure of the present invention, the fine pattern formed on the imprint mold structure efficiently enters the imprint resist layer on the substrate, and the imprint resist layer is formed from the pattern. Since the structure is easy to peel off, a pattern can be formed on the substrate with a high yield, which is suitable for manufacturing discrete media and patterned media.

FIG. 1 is a partial cross-sectional perspective view showing a configuration in an embodiment of an imprint mold structure according to the present invention. FIG. 2A is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Examples 1 to 5. FIG. 2B is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Examples 1 to 5. FIG. 3A is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Example 7. 3B is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Example 7. FIG. 4A is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Example 8. FIG. 4B is a cross-sectional view illustrating an example of a method for producing an imprint mold structure in Example 8. FIG. FIG. 5 is a sectional view showing a manufacturing method for manufacturing a magnetic recording medium using the imprint mold structure according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imprint mold structure 2 Substrate 2a Surface 3 Concavity and convexity 4 Convex part 5 Concave part 10 Si substrate 11 Si master 21 Photoresist layer 22 Conductive film 23 Ni substrate 24 Imprint resist layer 25 Imprint resist layer 30 Substrate 40 Substrate of magnetic recording medium 50 Magnetic layer 70 Nonmagnetic material 100 Magnetic recording medium

Claims (8)

A disk-shaped substrate and an uneven portion formed by arranging a plurality of protrusions on one surface of the substrate on the basis of the surface, and formed on another substrate An imprint mold structure used for transferring an uneven pattern based on the uneven portion to the imprint resist layer with the uneven portion facing the imprint resist layer, wherein the protruded portion is arranged. The imprint mold structure characterized in that a cross-sectional shape of the concavo-convex portion in a predetermined direction satisfies the following mathematical formulas (1) to (3).
40 ° ≦ θ <90 ° ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (1)
SRas> SRab ... Formula (2)
LRah> LRav ........................... Formula (3)
However, in the formula (1), θ (°) represents a wall angle formed by the surface and the side wall portion of the convex portion, and in the formula (2), SRas is a surface average roughness of the side wall portion. SRab represents the surface average roughness of the bottom of the concave portion, and in the above formula (3), LRah represents the line average roughness of the side wall portion in the direction in which the convex portion is extended, and LRav Represents the line average roughness of the side wall in the direction along the side wall.   The concavo-convex portion is a first concavo-convex portion in which a plurality of convex portions are formed concentrically with respect to a substantially central portion of the substrate, and a plurality of convex portions are formed radially with respect to the substantially central portion of the substrate. The imprint mold structure according to claim 1, comprising at least one of the second uneven portions.   3. The imprint mold structure according to claim 1, wherein the surface average roughness SRas of the side wall portion of the convex portion and the surface average roughness SRab of the bottom portion are both 0.1 nm or more and 10 nm or less.   The line average roughness LRah of the side wall part in the direction in which the convex part is extended and the line average roughness LRav of the side wall part in the direction along the side wall part are both 0.1 nm or more and 10 nm or less. The mold structure for imprints according to any one of 1 to 3.   The imprint mold structure according to any one of claims 1 to 4, wherein the imprint mold structure is made of any one of quartz, nickel, and resin.   The imprint mold structure according to any one of claims 1 to 5, wherein the imprint mold structure is pressed against an imprint resist layer made of an imprint resist composition formed on a substrate of a magnetic recording medium. An imprint method comprising at least a transfer step of transferring a concavo-convex pattern based on a concavo-convex portion formed on a body. An uneven pattern formed on the imprint mold structure by pressing the imprint mold structure according to any one of claims 1 to 5 against an imprint resist layer formed on a substrate of a magnetic recording medium. A transfer process for transferring
Using the imprint resist layer to which the concavo-convex pattern is transferred as a mask, the magnetic layer formed on the surface of the substrate of the magnetic recording medium is etched to form a magnetic pattern portion based on the concavo-convex pattern in the magnetic layer. A magnetic pattern portion forming step;
A non-magnetic pattern part forming step of embedding a non-magnetic material in the recess formed on the magnetic layer;
A method for producing a magnetic recording medium, comprising:   A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to claim 7.