JP2009241308A - Transparent mold structure for imprinting and imprinting method using transparent mold structure for imprinting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent mold structure for imprinting, etc. capable of preventing light reflection on a surface. <P>SOLUTION: The transparent mold structure for imprinting 1 includes; a transparent substrate 2; a plurality of projecting parts 3 disposed on one surface 5 of the transparent substrate 2; and a reflection preventing layer 4 formed on the other surface 7 of the transparent substrate 2. The reflection preventing layer 4 is made of MgF<SB>2</SB>, for example. In the transparent mold structure for imprinting 1, it is preferable that entire light transmittance with respect to light having a wavelength from 200 to 500 nm is 85% or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent mold structure for imprint and an imprint method using the transparent mold structure for imprint.

In recent years, discrete track media and patterned media have attracted attention as magnetic recording media capable of increasing recording density.
Discrete track media have nonmagnetic areas between adjacent tracks, and individual tracks are magnetically separated. Therefore, even if the track interval is set narrow in order to increase the recording density, the magnetic interference (crosstalk) between adjacent tracks can be suppressed by the nonmagnetic region.
Patterned media have bits for signal recording arranged regularly at a constant distance. Since each bit is independent, even if the bit interval is set narrow to increase the recording density, it has a feature that it is hardly affected by thermal fluctuation.

In the manufacture of the discrete track media and the bit patterned media, a transparent mold structure for imprinting is used. The transparent mold structure is made of a transparent material such as quartz and is used for forming a resist pattern on the surface of a processed substrate made of a magnetic material.
The resist pattern is formed by pressing a convex portion of the transparent mold structure against an imprint resist layer made of a photocurable resin formed on the surface of the processed substrate, and from the outside through the transparent mold structure. It is obtained by irradiating light and curing the imprint resist layer.

  When the imprint resist layer is cured, the transparent mold structure reflects a part of light irradiated from the outside on the surface. The light reflected from the surface of the transparent mold structure is not used for curing the imprint layer, and is wasted and is a problem.

  For example, Patent Document 1 discloses a transparent mold structure having a fine pattern on the surface and having a transmittance of 90% or more at a wavelength of 200 nm to 500 nm. However, the transparent mold structure has a problem that 3 to 4% of the irradiated light is reflected on the surface.

  Patent Document 2 discloses a molding stamper having a diamond-like thin film formed on the surface thereof. However, the diamond-like thin film does not have an antireflection function, and 3 to 4% of the irradiated light is reflected on the stamper surface, which is a problem.

JP 2006-182011 A Japanese Patent No. 2826827

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, an object of the present invention is to provide an imprint transparent mold structure in which light reflection on the surface is prevented, and an imprint method using the imprint transparent mold structure.

Means for solving the above problems are as follows. That is,
<1> An IN comprising: a transparent substrate; a plurality of protrusions disposed on one surface of the transparent substrate; and an antireflection layer formed on the other surface of the transparent substrate. This is a transparent mold structure for printing.
The imprinted transparent mold structure according to <1> prevents light reflection by an antireflection layer provided on the surface of the transparent substrate.
<2> The imprint transparent mold structure according to <1>, wherein the total light transmittance with respect to light having a wavelength of 200 nm to 500 nm is 85% or more.
<3> Reflecting while pressing the convex part of the transparent mold structure for imprints described in <1> or <2> to the imprint layer made of a photocurable resin formed on the surface of the processed substrate It is an imprint method characterized by irradiating light through a prevention layer to cure the imprint layer and forming a pattern on the surface of the processed substrate.
<4> The imprint method according to <3>, wherein the wavelength peak of light irradiated to the imprint layer is 250 nm to 400 nm.

  According to the present invention, there are provided a transparent mold structure for imprint that can solve the above-described problems and prevent light reflection on the surface, and an imprint method using the transparent mold structure for imprint. it can.

Hereinafter, the transparent mold structure for imprinting of the present invention will be described with reference to the drawings.
[Transparent mold structure for imprint]
FIG. 1 is a partial cross-sectional perspective view showing an outline of a transparent mold structure for imprinting according to an embodiment of the present invention. The transparent mold structure 1 includes a transparent substrate 2, convex portions 3, and an antireflection layer 5. The transparent mold structure 1 is used, for example, when manufacturing a magnetic recording medium such as a discrete track medium.

(Transparent substrate)
The transparent substrate 2 preferably has a total light transmittance of 85% or more with respect to light having a wavelength of 200 nm to 500 nm, more preferably 88% or more, and particularly preferably 90% or more.
When the transmittance is less than 85%, it is necessary to increase the amount of light and lengthen the light irradiation time in order to cure the photocurable resin, which may cause problems such as a decrease in the life of the light source and a decrease in throughput. is there.
The transmittance can be measured using a spectrophotometer.
The transmittance measurement method is as follows.After performing background correction, a sample is set, light is incident vertically, the amount of transmitted light after passing through the sample is measured, and compared with the amount of incident light. It can be obtained from the following formula.
Transmittance (%) = transmitted light amount / incident light amount × 100

The material of the transparent substrate 2 is not particularly limited as long as it satisfies the above transmittance and has an appropriate strength, and is appropriately selected according to the purpose. For example, quartz (SiO ₂ ), sapphire Transparent resin such as diamond, silicone resin, fluororesin, acrylic resin, polycarbonate resin, polyimide resin or the like is used. The transparent substrate 2 is most preferably quartz.
The “appropriate strength” means that the transparent mold structure 1 including the transparent substrate 2 can withstand, for example, when it is pressed against the imprint resist layer on the processing base material and pressed. It means strength.

There is no restriction | limiting in particular as thickness of the said transparent substrate 2, Although it selects suitably according to the objective, 0.1 mm-3.0 mm are preferable and 0.3 mm-1.5 mm are more preferable.
If the thickness of the transparent substrate 2 is less than 0.1 mm, it may be cracked by the pressure during imprinting, and if it exceeds 3.0 mm, it may be difficult to peel the cured photocurable resin from the mold. is there.

  The shape of the transparent substrate 2 is not particularly limited and is appropriately selected depending on the purpose. For example, in the transparent mold structure 1 for imprint used for manufacturing discrete track media and bit patterned media, A disc-shaped transparent substrate 2 is preferably used. In other embodiments, a square shape may be used.

(Convex)
A plurality of the convex portions 3 are arranged on one surface 5 of the transparent substrate 2. The convex portions 3 are formed on the surface 5 at a predetermined interval. There is a recess 6 between the protrusions 3.
When the transparent mold structure 1 is used for manufacturing a magnetic recording medium such as a discrete track medium, the convex portion 3 corresponds to a data portion, an alignment portion, a servo portion, etc. of the magnetic recording medium. Yes. When the convex portion 3 corresponds to the data portion, the convex portion 3 is disposed concentrically on the surface 5 of the disc-shaped transparent substrate 2. When the convex portions 3 correspond to the servo portions, the convex portions 3 are arranged radially on the surface 5 of the disc-shaped transparent substrate 2.

  The height of the convex portion 3 is not particularly limited and is appropriately selected depending on the purpose, but is preferably 10 nm to 800 nm, and more preferably 30 nm to 300 nm. The height of the convex portion 3 is the height from the surface 5 (reference surface) of the transparent substrate 2.

  The width of the convex portion 3 is not particularly limited and is appropriately selected depending on the purpose, but is preferably 1 nm or more, and more preferably 2 nm. The width of the convex portion 3 is a portion where the thickness of the convex portion 3 is the smallest in the direction along the surface 5. Therefore, in the imprint transparent mold structure 1 for producing discrete track media and the like, the radial thickness of the convex portion 3 disposed on the disc-shaped transparent substrate 2 is usually the convex portion. 3 width.

  It is preferable that the convex portion 3 extends on the transparent substrate 2 and is formed integrally with the transparent substrate 2.

(Antireflection layer)
The antireflection layer 4 is formed on the other surface 7 of the transparent substrate 2.
As the material of the antireflection layer 4, oxides such as SiO ₂ , Zr ₂ , Al ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , MgF ₂ , BaF ₂ , CaF ₂ , GdF ₃ , DyF ₃ , YF _{3 are used.} Inorganic halides such as PbF ₃ , AlF ₃ , LaF ₃ , LiF, NaF, SrF ₂ , Na ₃ AlF ₆ , and Na ₅ Al ₃ F ₁₄ can be used.

  There is no restriction | limiting in particular as thickness of the said reflection preventing layer 4, According to the objective, it selects suitably, 10 nm-1000 nm are preferable, and 50 nm-500 nm are more preferable.

  As a method for forming the antireflection layer 4, a known thin film forming method such as a vacuum deposition method, a sputtering method, or an ion plating method can be applied.

The reflectance of the antireflection layer 4 is preferably 3% or less, more preferably 2% or less, and still more preferably 1% or less.
The reflectance of the antireflection layer 4 can be measured with a spectrophotometer. As the spectrophotometer, for example, UV-3100PC manufactured by Shimadzu Corporation can be used.

The refractive index, thickness, and the like of the antireflection layer 4 can be appropriately designed based on known techniques described in JP-A-58-46391 and JP-A-59-49501.
In addition, it is preferable to wash the mold before forming the antireflection layer.

  The antireflection layer 4 may contain a conductive material such as ITO in order to prevent dust from adhering due to charging. The antireflection layer 4 may be a single layer or a multilayer.

  If the antireflection layer 4 is formed on the surface 7 of the transparent mold structure 1, light irradiated from the outside can be guided to the inside without being reflected. The antireflection layer 4 of the present invention also has a function of improving the scratch resistance.

[Method for producing transparent mold structure for imprint]
Hereinafter, the manufacturing method of the transparent mold structure for imprint which concerns on one Embodiment is demonstrated with reference to drawings.

(Preparation of master)
FIG. 2 is an explanatory view showing a method of manufacturing a master used for manufacturing a transparent mold structure for imprinting.
As shown in FIG. 2A, a photoresist layer 21 is formed on the Si substrate 10 by applying a photoresist solution such as polymethyl methacrylate (PMMA) by spin coating or the like.

  Thereafter, as shown in FIG. 2B, while rotating the Si substrate 10, the photoresist layer 21 is irradiated (exposed) with a laser beam 11 (or electron beam) modulated in accordance with a servo signal or the like. Then, a predetermined pattern (for example, servo pattern) is formed on the photoresist layer 21. In FIG. 2B, the exposed portion is indicated by reference numeral 12.

  Thereafter, as shown in FIG. 2C, the photoresist layer 21 is developed to remove the exposed portion 12. When the exposed portion 12 is removed, a resist pattern composed of a photoresist layer 21 appears on the Si substrate 10.

  Thereafter, as shown in FIG. 2D, selective etching such as reactive etching (RIE) is performed using the resist pattern as a mask. By this selective etching, the portion 13 where the resist layer 21 is not formed is dug down. After the selective etching, a plurality of convex portions 14 are formed on the surface of the Si substrate 10. Concave portions 15 are formed between the convex portions 14.

  Thereafter, as shown in FIG. 2E, when the resist layer 21 remaining on the convex portion 14 is removed, a master 16 having the convex portion 14 formed on the surface is obtained.

(Preparation of transparent mold structure for imprint)
Next, a method for manufacturing an imprint transparent mold structure using the master 16 will be described. FIG. 3 is an explanatory view showing a method for producing an imprint transparent mold structure.
As shown in FIG. 3F, an imprint resist solution is applied to the surface of a quartz substrate (transparent original substrate) 17 to form an imprint resist layer 22. The imprint resist solution contains at least one of a thermoplastic resin, a thermosetting resin, and a photocurable resin.

Thereafter, as shown in FIG. 3G, the convex portion 14 of the master 16 is pressed against the imprint resist layer 22. The imprint resist layer 22 exists in the concave portions 15 between the convex portions 14.
Thereafter, the imprint resist layer 22 is cured. For example, when the imprint resist layer 22 is made of a photocurable resin, light such as ultraviolet rays is irradiated through the quartz substrate (transparent original substrate) to cure the imprint resist layer 22.

Thereafter, as shown in FIG. 3H, when the master 16 is removed, a resist pattern composed of the cured imprint resist layer 22 appears on the surface of the quartz substrate (transparent master substrate).
Thereafter, selective etching such as RIE is performed on the quartz substrate (transparent original substrate) using the resist pattern as a mask to dig up the surface of the quartz substrate (transparent original substrate). Then, the convex part 3 is formed in the surface 5 of the transparent substrate 2, as FIG.3 (i) shows.

  Thereafter, as shown in FIG. 3J, the resist layer 22 remaining on the surface of the convex portion 3 is removed.

Thereafter, as shown in FIG. 3 (k), an antireflection layer 4 made of MgF ₂ is formed on the other surface 7 of the transparent substrate 2 where the convex portions 3 are not formed by a sputtering method. In this manner, a transparent mold structure for imprint including the antireflection layer 4 can be manufactured.

[Method of manufacturing magnetic recording medium]
Hereinafter, a method of manufacturing a magnetic recording medium such as a discrete track medium using the transparent mold structure for imprinting will be described.

(Imprint method using transparent mold structure for imprint)
FIG. 4 is an explanatory diagram showing an imprint process using the transparent mold structure for imprint in the manufacturing process of the magnetic recording medium.
As shown in FIG. 4L, an imprint resist solution containing a photocurable resin is applied to the surface of the magnetic layer 18 as a processing substrate to form an imprint resist layer 23. The magnetic layer 18 is made of, for example, Fe or an Fe alloy, Co, or a Co alloy. The magnetic layer 18 is formed on a substrate 19 made of aluminum, glass, quartz or the like.

  Thereafter, as shown in FIG. 4 (m), the convex portion 3 of the imprint transparent mold structure 1 is pressed against the imprint resist layer 23. When the convex portions 3 of the imprint transparent mold structure 1 are pressed, the imprint resist layer 23 is filled in the concave portions 6 between the convex portions 3.

Thereafter, as shown in FIG. 4 (n), the light 20 is irradiated through the antireflection layer 4 of the transparent mold structure 1, and the imprint resist layer 23 in the recess 6 is cured. The light 20 is irradiated from a light irradiation means (not shown).
Examples of the light irradiation means (light source) include a mercury lamp, xenon light, UV laser, and UV-LED.
If the light source has polarized light, a 4 / λ wavelength plate may be set in the optical path.

Λmax of the imprint resist layer 23 is preferably 250 nm to 400 nm, and more preferably 300 nm to 400 nm.
The λmax is the maximum absorption wavelength of the photopolymerization initiator contained in the photocurable resin used for the imprint resist layer 23.

  Since the transparent mold structure 1 includes the antireflection layer 4, reflection on the surface 7 is suppressed. As a result, light from the light irradiation means can be used for curing the imprint resist layer 23 without waste, and the life of the light irradiation means can be extended, throughput can be reduced, and manufacturing cost can be reduced.

  Thereafter, as shown in FIG. 4 (o), when the transparent mold structure 1 is removed, a resist pattern composed of a cured imprint resist layer 23 is formed on the surface of the magnetic layer 18 as a processing substrate. .

FIG. 5 is an explanatory view showing the manufacturing process of the magnetic recording medium.
As shown in FIG. 5 (p), the magnetic layer 18 as a processing substrate is formed by reactive ion etching (RIE), sputter etching, ion trimming method, or the like using the resist pattern made of the imprint resist layer 23 as a mask. Drill down the surface of the predetermined place.

  Thereafter, as shown in FIG. 5 (q), the imprint resist layer 23 remaining on the surface of the magnetic layer 18 is removed.

Thereafter, as shown in FIG. 5 (r), the gaps between the magnetic layers 18 are filled with the nonmagnetic material 20. Examples of the nonmagnetic material 20 include resins such as SiO ₂ , carbon, alumina, polymethyl methacrylate (PMMA), polystyrene (PS), and smooth oil.
If necessary, a protective layer made of diamond-like carbon (DLC), sputtered carbon or the like, and a lubricant layer made of fluorine resin or the like may be formed on the surfaces of the magnetic layer 18 and the nonmagnetic material 20. .
The magnetic recording medium 30 is obtained as described above.

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

[Example 1]
<Preparation of transparent mold structure 1 for imprint>
(Preparation of master)
A disk-shaped Si substrate was prepared, and an electron beam resist was applied on the Si substrate by a spin coating method to form a resist layer having a thickness of 100 nm on the Si substrate. Thereafter, the resist layer was exposed and developed using a rotary electron beam exposure apparatus. In this way, a resist pattern was formed on the surface of the Si substrate.

Thereafter, using the resist pattern as a mask, reactive ion etching was performed under the following conditions, and the surface of the Si substrate was dug down to form a pattern of convex portions.
<Reactive etching conditions>
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 washed and removed using a soluble solvent, and the Si substrate was dried to obtain a master.
The pattern formed on the master is roughly divided into a data portion and a servo portion.
The data portion consists of a pattern having a convex width: 120 nm and a concave width: 30 nm (TP = 150 nm).
The servo unit 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 portion is “0000101011”, the Sector uses Binary, and the Cylinder uses Gray conversion. The Burst part is a general phase burst signal (16 bits).

(Production of mold structure)
A photocurable acrylic imprint resist solution (Toyo Gosei Co., Ltd .: PAK-01) is applied to the surface of a quartz substrate (transparent base material) by a spin coating method, and the imprint is applied to the surface of the quartz substrate. A resist layer was formed.
Next, the imprint resist layer is transferred to the quartz substrate by irradiating the imprint resist layer with ultraviolet rays while irradiating ultraviolet rays, curing the imprint resist layer, and transferring the pattern of the master disc. Formed on the surface.

Thereafter, the master is removed, and the pattern of the imprint resist layer to which the pattern of the master is transferred is used as a mask to perform reactive ion etching under the following conditions, and the surface of the quartz substrate (transparent master) Then, a transparent substrate 2 having a convex portion on one surface was obtained.
<Reactive etching conditions>
Plasma source: ICP type (Inductively Coupled Plasma)
Gas: 1: 1 mixed gas of CF gas and Ar gas, and a small amount of hydrogen gas Pressure: 0.5 Pa
Input power: ICP = 300W, Bias = 60W

  Thereafter, the resist remaining on the convex portion was removed by washing with a soluble solvent.

Thereafter, a film made of MgF ₂ or the like as the antireflection layer 4 (four layers: the first layer 4a, the second layer 4b, the third layer 4c, and the fourth layer 4c is formed on the surface on which the convex portion is not formed. ) Was formed by sputtering as shown in FIG.
Table 1 shows the refractive index, thickness, and composition of the formed antireflection layer 4 and the like.

  As described above, an imprint transparent mold structure 1 provided with the antireflection layer 4 was obtained. In addition, the arrow shown with the code | symbol A in FIG. 6 represents a mode that a light source is incident.

[Evaluation]
The transmittance was evaluated using a spectrophotometer.
Using the spectrophotometer, the total light transmittance for light having a wavelength of 200 nm to 500 nm was determined.
As a result, the transmittance of the transparent mold structure 1 for imprint composed of the transparent substrate 2 (quartz mold) and the antireflection film 4 was 85%.
The reflectance of the antireflection film 4 itself was 0.5%.

[Comparative example]
Except not forming an antireflection film, it carried out similarly to the said Example, and obtained the transparent mold structure (transparent substrate 2) for imprints.
Further, the transmittance was evaluated in the same manner as in Example 1.
As a result, the transmittance of the transparent mold structure made of the transparent substrate 2 (quartz mold) was 82.5%.
Further, the reflectance of the surface of the transparent mold structure was 3%.

  From the above, it was confirmed that the transparent mold structure 1 for imprinting of Example 1 can reduce the reflectance of the surface by providing the antireflection film 4 as compared with the transparent mold structure of the comparative example.

FIG. 1 is a partial cross-sectional perspective view showing an outline of a transparent mold structure for imprinting. FIG. 2 is an explanatory view showing a method of manufacturing a master used for manufacturing a transparent mold structure for imprinting. FIG. 3 is an explanatory view showing a method for producing an imprint transparent mold structure. FIG. 4 is an explanatory view showing an imprint method using a transparent mold structure for imprint. FIG. 5 is an explanatory diagram showing a method for manufacturing a magnetic recording medium. FIG. 6 is an explanatory view showing an outline of a transparent mold structure for imprinting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent mold structure for imprint 2 Transparent substrate 3 Convex part 4 Antireflection layer 5 Concave part 6 One surface of a transparent substrate 7 The other surface of a transparent substrate

Claims (4)

A transparent substrate;
A plurality of convex portions disposed on one surface of the transparent substrate;
An imprinting transparent mold structure comprising: an antireflection layer formed on the other surface of the transparent substrate.   The transparent mold structure for imprints according to claim 1, wherein the total light transmittance for light having a wavelength of 200 nm to 500 nm is 85% or more.   Light is transmitted through the antireflection layer while pressing the convex portions of the transparent mold structure for imprinting according to claim 1 or 2 against an imprint layer made of a photocurable resin formed on the surface of the processed substrate. The imprint method is characterized in that the imprint layer is cured to form a pattern on the surface of the processed substrate.   The imprint method according to claim 3, wherein a wavelength peak of light irradiated to the imprint layer is in a range of 250 nm to 400 nm.