JP2008287805A - Mold structure and imprint method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold structure capable of reducing a residual film, excellent in uniformity of a residual film over the entire surface of a substrate, having improved durability and allowing a high-quality pattern to be transferred and formed in a discrete track media and a patterned media, and to provide an imprint method using the mold structure. <P>SOLUTION: The mold structure comprises a disk substrate and a rugged pattern formed on one surface of the substrate by arranging a plurality of projections, wherein a ratio [(Rz/H)×100] of a ten-point average roughness at the top of the projection to the height H of the projection ranges from 10% to 50%. In a preferred form, the ten-point average roughness Rz at the top of the projection is not less than 10 nm. <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 and an imprint method using the mold structure.

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. Therefore, a technique for improving the recording density is demanded.
In order to increase the recording density of a hard disk drive, high-performance magnetic recording media and narrowing the magnetic head width have been used, but the effect of magnetism between adjacent tracks by narrowing the data track interval ( (Crosstalk) and thermal fluctuations 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 the noise caused by the crosstalk (see Patent Documents 1 and 2). In this discrete track medium, a nonmagnetic guard band region is provided between adjacent tracks to form a discrete structure in which individual tracks are magnetically separated, thereby reducing magnetic interference between adjacent tracks.

  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 (see Patent Document 3). .

  When the discrete track media and the patterned media are manufactured, as disclosed in Patent Document 4, a resist pattern forming mold (hereinafter sometimes referred to as “stamper”) is used to form a magnetic surface. There is an imprint method in which a desired pattern is transferred to a resist layer formed on a magnetic recording medium substrate having a layer.

In this imprint method, a transfer process is required many times from the viewpoint of cost reduction, and the durability of the mold capable of transferring at least several hundred to several tens of thousands of times is required.
In addition, when an information recording medium such as a hard disk or an optical disk is manufactured using an imprint method, a fine pattern processing can be performed by a wet etching method or a dry etching method using an organic resist pattern formed by the imprint process as a mask. Done.
However, before these fine patterns are processed, it is necessary to remove the residual film generated in the resist pattern after the imprint process. Therefore, in addition to reducing the remaining film as much as possible, the uniformity of the remaining film over the entire surface of the substrate is important.
In order to reduce such a residual film and improve the uniformity of the residual film on the entire surface of the substrate, various imprint apparatuses aiming at pressure uniformity in the imprint process have been developed. However, even when these imprint apparatuses are used, the remaining film depends on the uneven pattern of the mold structure to be used. For example, in a concavo-convex pattern having a rectangular cross-sectional shape in the arrangement direction as described in Non-Patent Document 1, Patent Document 4, and Patent Document 5, when pressing against the resist layer, the resist layer is applied with sufficient pressing force. It cannot be extruded, and stress concentrates at both ends compared to the central portion of the convex portion, so that the remaining film at the central portion of the convex portion tends to be thick. Furthermore, there is a problem that non-uniformity of the remaining film occurs in a fine area due to the density of the pattern.

  Therefore, a mold structure that can reduce the remaining film, has excellent uniformity of the remaining film on the entire surface of the substrate, has improved durability, and can form a high-definition pattern has not yet been realized. The current situation is.

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 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 can reduce the residual film by forming the surface roughness of the top of the convex part within an appropriate range, and can improve the durability of the residual film as well as the uniformity of the residual film over the entire surface of the substrate. Another object of the present invention is to provide a mold structure capable of transferring and forming a high-quality pattern on a discrete track medium and a patterned medium, and an imprint method using the mold structure.

  As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, by forming the surface roughness of the top of the convex portion within a proper range, the sectional shape of the convex portion is conventionally rectangular. It was found that the resist layer that could not be fully pressed could function as a buffer, the remaining film could be reduced to 0 (zero) as much as possible, and the uniformity of the remaining film over the entire surface of the substrate was improved. In the present invention, a spike-like resist residue corresponding to the surface roughness of the top of the convex portion is generated in the concave portion of the resist pattern after imprinting. In the next ashing process, the spike-like resist residue is plasma. This is not a problem because it can be removed relatively early because of the large surface area exposed to. However, if the surface roughness of the top of the convex part is too large, pressure will concentrate on the formed protrusions and cause damage, so if durability is taken into consideration, the surface roughness of the top part of the convex part is appropriate. It has been found that it is effective to form a large layer within a certain range.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A mold structure having a disc-shaped substrate and a concavo-convex portion formed by arranging a plurality of convex portions on one surface of the substrate,
The mold structure is characterized in that a ratio [(Rz / H) × 100] of the 10-point average roughness Rz of the top part of the convex part to the height H of the convex part is 10% to 50%. .
<2> The mold structure according to <1>, wherein the top 10-point average roughness Rz of the convex portion is 10 nm or more.
<3> The mold structure according to any one of <1> to <2>, wherein a length of the convex portions in the arrangement direction is 100 nm or less.
<4> The mold structure according to any one of <1> to <3>, which is made of any material of quartz, metal, and resin.
<5> The mold structure according to any one of <1> to <4> is pressed against an imprint resist layer made of an imprint resist composition formed on a magnetic recording medium substrate. It is an imprint method characterized by including the transfer process which transfers the uneven | corrugated pattern based on the uneven | corrugated | grooved part formed in the body at least.
<6> A method of manufacturing a magnetic recording medium, wherein a magnetic recording medium is manufactured using the imprint method according to <5>.
<7> The method for producing a magnetic recording medium according to <6>, wherein the magnetic recording medium is at least one of a discrete magnetic recording medium and a patterned media magnetic recording medium.
<8> A magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium according to any one of <6> to <7>.
<9> The 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.

  According to the present invention, various problems in the prior art can be solved, and the remaining film can be reduced and the uniformity of the remaining film over the entire surface of the substrate is excellent by forming the surface roughness of the top of the convex portion within an appropriate range. In addition, durability can be improved, and a mold structure capable of transferring and forming a high-quality pattern on a discrete track medium and a patterned medium and an imprint method using the mold structure can be provided. .

(Mold structure)
The mold structure of the present invention has a disk-shaped substrate and a concavo-convex portion formed by arranging a plurality of convex portions on one surface of the substrate. It has a configuration.

  In the present invention, the ratio [(Rz / H) × 100] of the 10-point average roughness Rz of the top part of the convex part to the height H of the convex part is 10% to 50%, 15% to 40% is preferred. If the ratio [(Rz / H) × 100] is less than 10%, the effect of reducing the residual film after imprinting due to resist flow, which is the object of the present invention, may not be expected, and if it exceeds 50%, The uneven thickness (residue) of the remaining film portion may cause variations in subsequent pattern processing.

The 10-point average roughness Rz at the top of the convex portion is preferably 10 nm or more, and more preferably 15 nm to 50 nm. If the 10-point average roughness Rz is less than 10 nm, the effect of reducing the residual film after imprinting due to resist flow, which is the object of the present invention, may not be expected.
Here, the ten-point average roughness Rz at the top of the convex portion is the average of the five highest deviation values from the average deviation value from the average value of the surface roughness, and the lowest five from the smallest. The surface roughness can be measured by, for example, an atomic force microscope (AFM).
The height H of the convex portion means a distance from the lowest point of the convex portion 3a (reference surface 2a) to the top portion of the convex portion 3a (the highest point of the projections on the top portion), as shown in FIG. 10 nm to 100 nm is preferable.
The height H of the convex portion can be measured by, for example, an atomic force microscope (AFM) or a cross-sectional scanning electron microscope (cross-section SEM).

There is no restriction | limiting in particular as a 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), and a low melting point fluororesin.

Here, FIG. 1 is a partial perspective view showing a configuration of an embodiment of a mold structure according to the present invention, and FIG. 2 is a schematic sectional view taken along line AA of FIG. In addition, although the fine unevenness | corrugation is formed in the top part 4 in the convex part 3a of FIG. 1 over the whole surface, a part is abbreviate | omitted and it has shown typically in FIG.
The mold structure 1 shown in FIG. 1 is formed by concentrically forming a plurality of convex portions 3a and concave portions 3b on one surface 2a (hereinafter sometimes referred to as a reference surface 2a) of a substrate 2 having a disc shape. . In this case, 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.
In addition, the cross-sectional shape in the arrangement direction of the convex portions 3a is not limited to a rectangle, and an arbitrary shape can be selected by controlling an etching process described later according to the purpose.
In the present invention, the “cross section (shape)” of the convex portion 3a refers to a cross section (shape) in the arrangement direction of the convex portions 3a (the direction in which the convex portions 3a are arranged) unless otherwise specified.
The length L in the arrangement direction of the convex portions 3a is preferably 100 nm or less, and more preferably 90 nm or less. If the length of the convex portion in the radial direction exceeds 100 nm, the recording density of the magnetic recording medium that is the object of the present invention may not be increased.
The length of the projections in the arrangement direction can be obtained by, for example, measuring the cross-sectional shape with a scanning electron microscope (SEM) or an atomic force microscope (AFM) and calculating the half width of the height standard. it can.
Moreover, it is preferable that the thickness of the board | substrate 2 is 0.5 mm or more and 10 mm or less.

  There is no restriction | limiting in particular as a method of forming the surface roughness of the top part 4 in the said convex part 3a large within a suitable range (10-point average roughness Rz is 10 nm or more), It can select suitably according to the objective. For example, (1) a method in which the mold structure is ion-implanted into the bottom of the concave portion of the master before processing, and physical processing such as blasting is performed, and (2) the bottom of the concave portion of the master before processing the mold structure. Examples include a method of chemically treating by surface chemical reaction, and (3) a method of physically treating or chemically treating the top of the convex portion of the produced mold structure.

<Method for producing mold structure>
Hereinafter, a method for producing a mold structure according to the present invention will be described with reference to FIGS.
-Production of master-
FIG. 3 is a cross-sectional view showing an example of production of a master in the method for producing a mold structure of the present invention.
As shown in FIG. 3A, first, a photoresist solution 21 is formed on the Si substrate 10 by applying a photoresist solution by a spin coating method or the like. The material for the photoresist layer may be either a positive resist material or a negative resist material.
Next, as shown in FIG. 3B, 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 information is irradiated to form a photoresist. A predetermined pattern on the entire surface, for example, a pattern corresponding to a servo signal extending linearly in the radial direction from the center of rotation on each track is exposed to a portion corresponding to each frame on the circumference.
Next, as shown in FIG. 3C, the photoresist layer 21 is developed, and a desired uneven pattern is formed by the photoresist layer 21 remaining after removing the exposed portion.
Next, as shown in FIG. 3D, a concavo-convex pattern is formed on the substrate 10 by performing selective etching by RIE (Reactive Ion Etching) using the pattern of the formed photoresist layer 21 as a mask. To do.
Next, as shown in FIG. 3E, the remaining photoresist layer 21 is removed, and the master 11 having an uneven shape is produced.

-Fabrication of mold structure-
FIG. 4 is a cross-sectional view showing an example of production of a mold structure in the method for producing a mold structure of the present invention.
As shown to A of FIG. 4, with respect to the quartz board | substrate 30 as a to-be-processed substrate in which the imprint resist layer 24 formed by apply | coating the imprint resist liquid containing a photocurable resin was formed in one surface, The master 11 is pressed, and the pattern of the protrusions formed on the master 11 is transferred to the imprint resist layer 24.
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 ), resin (PET, PEN, polycarbonate, low melting point fluororesin) 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.

  Next, as shown in FIG. 4B, the imprint resist layer 24 is irradiated with ultraviolet rays or the like to cure the transferred pattern.

Next, as shown in FIG. 4C, selective etching was performed by RIE or the like using the transferred pattern as a mask.
Thereafter, the top of the convex part of the produced mold structure is ion-implanted and subjected to physical treatment such as blasting or chemical treatment, or chemical treatment, as shown in FIG. A mold structure 1 having a thickness Rz of 10 nm or more can be produced.

3A to E in FIG. 3 is used, a conductive film is formed on the surface of the master by sputtering, and the master provided with the conductive film is immersed in a Ni electroforming bath. The Ni mold structure can also be manufactured by performing electroforming. The bottom of the concave portion of the master is physically or chemically processed so that the surface roughness of the top of the convex portion can be increased within an appropriate range.
3 is used to press the master against the substrate on which the resin layer is formed. Then, the pattern of the convex part formed on the original disk is transcribe | transferred to a resin layer by heating and making it the state which lowered | hung the viscosity of resin. Thereafter, the pattern transferred by cooling is cured, and the resin layer is peeled from the substrate, whereby a resin mold structure having an uneven shape can be produced. The bottom of the concave portion of the master is physically or chemically processed so that the surface roughness of the top of the convex portion can be increased within an appropriate range.
Examples of the resin in the resin layer include polymethyl methacrylate (PMMA), novolac resin, and fluorine resin.

  The mold structure of the present invention is suitably used in an imprint method including at least a transfer step of transferring the concavo-convex pattern to the imprint resist layer with the convex portion of the mold structure facing the imprint resist layer. It is particularly suitable for the method for producing a magnetic recording medium described below.

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

As shown in FIG. 5A, an imprint resist layer 24 obtained by applying a magnetic layer 50 and an imprint resist composition containing polymethyl methacrylate (PMMA) or the like on a magnetic recording medium substrate 40; Are formed on the mold structure 1 by pressing and pressurizing the mold structure 1 having a large surface roughness at the top of the convex portion within an appropriate range against the magnetic recording medium formed in this order. The pattern of the uneven portion thus formed is transferred to the imprint resist layer 24. Note that, although a resist residue having a spike shape corresponding to the surface roughness of the top of the convex portion is generated in the resist layer, it is easily removed in the next ashing step.
Here, as the imprint resist layer 24, for example, an imprint resist composition containing at least one of a thermosetting resin and a photocurable resin (hereinafter sometimes referred to as an imprint resist solution) is used as a magnetic recording medium. It is a layer formed by apply | coating to the board | substrate.
The material of the resist layer may be either a positive resist material or a negative resist material.
The material of the magnetic layer is not particularly limited and can be appropriately selected from known materials according to the purpose. For example, Fe, Co, Ni, FeCo, FeNi, CoNi, CoNiP, FePt, CoPt, NiPt etc. are mentioned suitably. These may be used individually by 1 type and may use 2 or more types together.

  Next, as shown in FIG. 5B, when the mold structure 1 is pressed against the imprint resist layer 24, the system is maintained near the glass transition temperature (Tg) of the resist solution, and after transfer, The imprint resist layer 24 is cured by lowering the glass transition temperature of the resist solution.

Next, as shown in FIG. 5C, selective etching is performed by RIE using the imprint resist layer 24 to which the pattern of the concavo-convex portion is transferred as a mask, based on the pattern shape formed on the mold structure 1. An uneven shape is formed in the magnetic layer 50.
Next, as shown in FIG. 5D, the magnetic recording medium 100 can be manufactured by embedding a nonmagnetic material 70 in the recesses and planarizing the surface, and then forming a protective film or the like as necessary. .
Examples of the non-magnetic material include SiO ₂ , carbon, alumina; polymers such as polymethyl methacrylate (PMMA) and polystyrene (PS); and smooth oil.
The protective film is preferably diamond-like carbon (DLC), sputtered carbon or the like, and a lubricant layer may be further provided on the protective film.

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

Example 1
<Manufacture of mold structure>
-Production of master-
As shown in FIG. 3A, first, a photoresist solution containing methyl polymethacrylate (PMMA) was applied on a disk-shaped Si substrate 10 by spin coating to form a photoresist layer 21.
Next, as shown in FIG. 3B, while the Si substrate 10 is rotated, a laser beam modulated in accordance with the servo signal is irradiated to linearly extend from the rotation center to each track on the entire surface of the photoresist layer. A pattern corresponding to the servo signal extending in (1) was exposed at portions corresponding to each frame on the circumference.
Next, as shown in FIG. 3C, the photoresist film 21 was developed, and a desired uneven pattern was formed by the resist film 16 remaining after removing the exposed portion.
Next, as shown in FIG. 3D, selective etching is performed by RIE using the pattern of the removed photoresist layer 21 as a mask, and the excess photoresist layer is removed to form the uneven shape shown in FIG. A master 11 having the same was produced.

-Fabrication of mold structure-
Next, as shown in FIG. 4A, the master 11 is pressed against the quartz substrate 30 on which the imprint resist layer 24 formed by applying an imprint resist solution containing a photocurable resin is formed, The pattern of the convex portion formed on the master 11 is transferred to the imprint resist layer 24.
Thereafter, the imprint resist layer 24 is irradiated with ultraviolet rays or the like to cure the transferred pattern, and using the pattern as a mask, selective etching is performed by RIE (Reactive Ion Etching) to form the mold structure 1. Produced.
In order to increase the surface roughness of the top of the convex portion of the obtained mold structure within an appropriate range, Ar ion implantation was performed using an ion source.

<Preparation of magnetic recording medium>
As shown in FIG. 5A, a magnetic layer 50 and an imprint resist layer 24 formed by applying an imprint resist composition containing polymethyl methacrylate (PMMA) on a magnetic recording medium substrate 40. Then, the magnetic recording medium having this order was formed on the mold structure 1 by pressing and pressurizing the mold structure 1 in which the surface roughness of the top of the convex portion was increased within an appropriate range. The pattern of the uneven portion was transferred to the imprint resist layer 24.
Next, as shown in FIG. 5B, when the mold structure 1 is pressed against the imprint resist layer 24, the system is maintained near the glass transition temperature (Tg) of the resist solution, The imprint resist layer 24 is cured by lowering the glass transition temperature of the resist solution.
Next, as shown in FIG. 5C, selective etching is performed by RIE using the imprint resist layer 24 to which the pattern of the concavo-convex portion is transferred as a mask, based on the pattern shape formed on the mold structure 1. An uneven shape was formed in the magnetic layer 50, a nonmagnetic material 70 was embedded in the recess, and the surface was flattened to produce the magnetic recording medium 100 shown in FIG. 5D.

(Examples 2-3 and Comparative Examples 1-2)
In Example 1, as shown in Table 1, the same as Example 1 except that the top 10-point average roughness Rz, the height H of the convex part, and the arrangement direction length of the convex part were changed as shown in Table 1. Thus, mold structures of Examples 2 to 3 and Comparative Examples 1 to 2 were produced.
In addition, the bottom of the concave portion of this master is formed by performing ion implantation using Ar gas after RIE using an ICP etching apparatus, so that the surface roughness of the top portion of the convex portion is increased within an appropriate range. Surface roughness is imparted.
A magnetic recording medium was produced by imprinting using the produced mold structures in the same manner as in Example 1.

Example 4
A master having a concavo-convex pattern was produced in the same manner as in Example 1. In addition, the bottom of the concave portion of this master is formed by performing ion implantation using Ar gas after RIE using an ICP etching apparatus, so that the surface roughness of the top portion of the convex portion is increased within an appropriate range. Surface roughness is imparted.
Next, the master was pressed against a resin sheet made of polymethyl methacrylate (PMMA). Then, the viscosity of the resin was lowered by heating to a temperature equal to or higher than the softening point of the resin, and the pattern of the convex portions 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.
A magnetic recording medium was produced by imprinting using the produced resin mold structure in the same manner as in Example 1.

(Example 5)
A master having a concavo-convex pattern was produced in the same manner as in Example 1. In addition, the bottom of the concave portion of this master is formed by performing ion implantation using Ar gas after RIE using an ICP etching apparatus, so that the surface roughness of the top portion of the convex portion is increased within an appropriate range. Surface roughness is imparted.
Next, based on the uneven pattern on the surface of the master 11, a conductive film was formed on the surface by sputtering. The master disk to which the conductive film was applied was immersed in a Ni electroforming bath having the following composition and rotated at a rotational speed of 50 rpm to 150 rpm, and electroforming was performed to produce a 300 μm thick Ni disk. Thereafter, the Ni disc was peeled from the master disc, and the remaining resist film was removed and washed. As described above, the Ni mold structure of Example 5 was produced.
-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 ℃
A magnetic recording medium was manufactured by imprinting using the manufactured Ni mold structure in the same manner as in Example 1.

  Next, for Examples 1 to 5 and Comparative Examples 1 and 2, the top 10-point average roughness Rz, the height H of the projections, and the arrangement direction of the projections in the projections of the mold structure as follows The length, amount of remaining film, and durability were evaluated. The results are shown in Table 1.

<Measurement of 10-point average roughness Rz at the top of the convex portion>
The 10-point average roughness Rz at the top of the convex portion is the average of the absolute values of the deviation values from the average to the top five deviation values and the minimum to the bottom five deviation values. The surface roughness was measured with an atomic force microscope (AFM).

<Measurement of the height H of the convex portions and the length in the arrangement direction of the convex portions>
The height H of the convex portion was measured with a scanning electron microscope (SEM) or an atomic force microscope (AFM).
The length in the arrangement direction of the convex portions was obtained by measuring the cross-sectional shape with a scanning electron microscope (SEM) or an atomic force microscope (AFM) and calculating the half width of the height standard.

<Evaluation of remaining film amount>
When the concave / convex fine pattern was transferred to the resist layer formed on the substrate side using each mold structure produced, the residual resin amount of the resist layer of each mold structure was measured with a cross-sectional transmission electron microscope (TEM). The average value was obtained and evaluated according to the following criteria.
〔Evaluation criteria〕
○: The value of the remaining film amount is less than 20% of the pattern height. X: The value of the remaining film amount is 20% or more of the pattern height.

<Durability evaluation>
The process of transferring the concave / convex fine pattern onto the resin formed on the substrate side was repeated 100 times using each mold structure produced, and after that process, each mold was measured with an atomic force microscope (AFM). Four 1 μm square areas were measured every 90 ° at a radius position of 25 mm of the structure, and the presence or absence of clogging and pattern collapse was evaluated according to the following criteria.
〔Evaluation criteria〕
A: The depth of the recess is a pattern with a predetermined depth of less than 40%, and there is no pattern collapse.
X: It is a pattern whose depth of a recessed part is less than predetermined 40%, and one or more pattern collapse exists.

  The mold structure of the present invention and the imprint method using the mold structure can reduce the residual film by forming the surface roughness of the top of the convex portion within an appropriate range, thereby reducing the remaining film on the entire surface of the substrate. The film is excellent in film uniformity and durability, and is suitable for manufacturing discrete media and patterned media.

FIG. 1 is a partial perspective view showing an example of a mold structure of the present invention. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. FIG. 3 is a process diagram showing the production of a master in the method for producing a mold structure of the present invention. FIG. 4 is a process diagram showing the production of a mold in the method for producing a mold structure of the present invention. FIG. 5 is a process diagram showing a method of manufacturing a magnetic recording medium using the mold structure of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold structure 2 Substrate 3 Uneven part 3a Convex part 3b Concave part 4 Top part 24 Imprint resist layer 40 Substrate for magnetic recording media 50 Magnetic layer 100 Magnetic recording medium

Claims (5)

A mold structure having a disk-shaped substrate and uneven portions formed by arranging a plurality of protrusions on one surface of the substrate,
The mold structure characterized in that the ratio [(Rz / H) × 100] of the 10-point average roughness Rz of the top part of the convex part to the height H of the convex part is 10% to 50%.   The mold structure according to claim 1, wherein the 10-point average roughness Rz at the top of the convex portion is 10 nm or more.   The mold structure according to claim 1, wherein the length of the convex portions in the arrangement direction is 100 nm or less.   The mold structure according to any one of claims 1 to 3, wherein the mold structure is made of any one of quartz, metal, and resin.   The uneven structure formed in the said mold structure by pressing the mold structure in any one of Claim 1 to the imprint resist layer which consists of an imprint resist composition formed on the board | substrate for magnetic recording media An imprint method comprising at least a transfer step of transferring a concavo-convex pattern based on a portion.

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