JPH1139731A - Method of manufacturing mold for resin plate and method of manufacturing resin plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing technique of a mold in which irregularities are accurately formed in accordance with the outer peripheral shape of a resist by removing distortion of the outer peripheral shape of a patterned resist, thereby providing a correct original signal. It is possible to manufacture a resin plate that can restore the above. SOLUTION: A resist layer forming step of forming a resist layer on a recording surface of a master, an exposure step of shielding the resist layer according to predetermined information and then exposing, a developing step of developing the resist layer, and a step on the resist layer A resin layer forming step of forming a resin layer, a resist layer is heated to a certain temperature Tg, a heating step of softening the resist, and the temperature is lowered to a temperature at which the softened resist is cured again. And a removing step of removing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for manufacturing a resin plate having an uneven surface on its surface, such as an optical recording medium, and more particularly to a resin plate for an optical recording medium or the like on which high-density recording is performed. The present invention relates to improvement of a mold for producing a resin plate suitable for the production of a resin sheet.

[0002]

2. Description of the Related Art An optical recording medium records and reproduces information using a minute light spot. The information recording surface has guide grooves for positioning the light spot.
For example, pits and the like for recording a preformat signal corresponding to the information are formed in advance as an uneven pattern.
Such an optical recording medium has generally been manufactured by transferring a concave and convex shape to a resin material or the like using a mold having a concave and convex shape corresponding to recording information, that is, a stamper.

As shown in FIG. 5, a stamper used for manufacturing this optical recording medium is generally manufactured by applying a lithography technique. First, the surface of a glass master 500 as shown in FIG. 1A is mirror-polished and cleaned, and then the surface is dried. Next, a resist layer 600 is formed on the glass master 500 as shown in FIG. After the resist layer 600 is exposed to light modulated according to information to be recorded on the optical recording medium as shown in FIG. The patterned resist layer 60
0 is left.

Subsequently, as shown in FIG. 1E, the surface of the information recording surface is formed on the conductive layer 701 by sputtering or the like.
Is formed, a nickel layer 702 is formed by an electroforming method as shown in FIG.

As shown in FIG. 1G, the stamper 700 is manufactured by peeling the nickel layer 702 from the glass master 500 and processing the inner and outer diameters into a disk shape by a punching process.

However, according to these general methods for manufacturing an optical recording medium, the surface of the patterned resist layer 600 becomes rough in the developing step as shown in FIG. In particular, as shown in FIG. 4, the degree of the roughness tends to be larger on the side wall b than on the upper surface a of the resist layer. Such roughness of the resist layer is directly transferred to the stamper. If an optical recording medium is manufactured using this stamper, the roughness transferred to the stamper is further transferred to the information recording surface of the optical recording medium.

[0007] The roughness transferred to the information recording surface of the optical recording medium causes the amplitude of the RF signal reproduced from the pickup to fluctuate in the reproducing apparatus for the optical recording medium. Variations in the RF signal amplitude prevent correct decoding of the signal.
Therefore, there is a possibility that correct signal reproduction cannot be performed from an optical recording medium duplicated from a stamper manufactured by a conventional general manufacturing method.

Japanese Patent Application Laid-Open No. 5-220751 describes a technique using silicon or quartz as a stamper for an optical recording medium. This technique is similar to the above-described general method for manufacturing a stamper for an optical recording medium.
A patterned resist layer is formed in the same manner as in the steps shown in FIGS. 3A to 3D, and silicon or quartz itself is etched and used as a stamper. However, even with this method, the surface roughness of the resist layer has been transferred to the stamper and the recording medium.

On the other hand, Japanese Patent Application Laid-Open No. Hei 3-176841 discloses a technique in which after a resist layer is patterned, a hardening heat treatment is performed at a temperature near a melting point of the resist material to reduce the roughness of the resist layer surface. It has been disclosed.

However, according to this method, there is a problem that the pattern shape of the resist layer is deformed instead of reducing the roughness of the resist layer surface. This problem has been a serious problem particularly in optical recording media for high-density recording, which has been actively developed in recent years, because a slight deformation of the shape causes a large deterioration of a reproduced signal.

[0011]

Therefore, the first aspect of the present invention
In view of the above problems, the problem is to reduce the roughness of the resist surface without deforming the pattern shape formed on the resist layer, thereby forming a mold in which the concavo-convex shape is accurately formed as in the outer peripheral shape of the resist. Providing manufacturing technology
Thus, it is possible to manufacture a resin plate capable of restoring a correct original signal.

A second object of the present invention is to provide a combination of materials suitable for removing the surface roughness of a patterned resist.

A third object of the present invention is to provide a temperature condition suitable for removing the surface roughness of a patterned resist.

[0014]

SUMMARY OF THE INVENTION The first aspect of the present invention is to solve the first problem, and is intended to transfer a concave and convex shape formed on a recording surface of a master to a resin plate. A method of manufacturing a mold, wherein (a) a resist layer forming step of forming a resist layer on the recording surface of the master, and (b) the resist layer formed on the recording surface of the master according to predetermined information. Exposure step of exposing, (c) a developing step of developing the exposed resist layer, and (d) a resin layer forming step of forming a resin layer on the developed resist layer,
(e) maintaining the resist layer on which the resin layer is formed at a constant temperature T
s, and a heating step of softening the resist,
(f) up to a temperature at which the softened resist hardens again;
Removing the resin layer from the resist layer after lowering the temperature of the resist layer.

According to the present invention, in the heat treatment for reducing the surface roughness of the resist, the pattern shape is prevented from being deformed due to the softening of the uneven pattern. That is, since the original uneven shape is maintained by the resin layer even when the resist layer is softened, the pattern shape of the resist layer after the resin layer is removed is not changed, and the surface roughness due to the heat treatment is also reduced. .

The uneven shape refers to an intentionally formed undulation, for example, a pit for recording information on an optical recording medium and a groove serving as a guide groove for information reproduction. The resin plate refers to a resin plate formed of a general molding material, and it does not matter whether the surface is flat or curved. For example, it refers to a disc in the form of an optical recording medium.

The invention according to claim 2 solves the second problem, and the composition of the resin layer is selected such that the resin layer is softened at a temperature Ts at which the resist softens. The method for manufacturing a resin plate manufacturing mold according to claim 1, wherein

The third aspect of the present invention is to solve the third problem, and the temperature Ts at which the resist softens is:
The method according to claim 2, wherein the temperature is in a range of 100C to 300C.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a resin plate manufacturing mold according to the first aspect, wherein the master is made of silicon.

According to a fifth aspect of the present invention, a first object is achieved, and a mold manufactured by the method for manufacturing a resin plate manufacturing mold according to any one of the first to sixth aspects. In the method for manufacturing a resin plate by using a method, a step of providing a molding material on the recording surface of the mold in which the irregular shape is formed, and after the molding material is cured, peeling the cured resin plate from the mold A method for manufacturing a resin plate, comprising:

[0021]

Next, preferred embodiments of the present invention will be described with reference to the drawings.

The present embodiment relates to a method for manufacturing a stamper (hereinafter, referred to as a stamper) used for manufacturing an optical recording medium, which removes roughness of a patterned resist layer surface.

The stamper manufactured in the present embodiment is formed by forming an irregular shape on a disk-shaped master 100 as shown in FIG. As the material of the master 100, crystalline or amorphous silicon or quartz is used.

(Manufacturing Process of Stamper) Next, the manufacturing process of the stamper will be described with reference to FIG. 2, and the manufacturing process of the optical recording medium will be described with reference to FIG. 2 and 3 are cross-sectional views showing the manufacturing process of the master 100 as viewed from a cut surface aa in FIG.

Grinding Step (FIG. 2A): First, high-purity silicon is ground into a disk shape, and its recording surface is precisely polished to a certain surface roughness or less to manufacture a master 100. The upper surface in FIG. 2 is a precisely polished recording surface.

Resist Layer Forming Step (FIG. 2B): Master 1
The resist layer 200 is formed on the recording surface of No. 00. The substance forming the resist layer 200 is preferably a material that softens at a certain temperature Ts in a patterned state. In order to facilitate the temperature control, it is preferable that the resist is made of a material which does not have excessive fluidity and can maintain an appropriate softened state in a temperature range as wide as possible. For example, a commercially available positive resist obtained by blending a diazonaphthoquinone derivative as a photosensitive agent with a cresol novolak-based resin, which is generally used in a semiconductor device manufacturing process, can be used. According to this material, the softened state is exhibited in a temperature range of 100 ° C. to 300 ° C., so that it is preferable as a material used in the present embodiment. Here, a positive resist is a substance that allows an exposed region to be selectively removed with a developer.

As a method of forming the resist layer 200, a method such as a spin coating method, a dipping method, a spray coating method, a roll coating method, and a bar coating method can be used.

Exposure Step (FIG. 2C): Exposure is performed so that the resist layer 200 remains in a region where etching is not desired. When a positive resist is used, a region corresponding to a region to be etched is exposed.

Developing step (FIG. 2D): When a positive resist is used, the exposed area is easily dissolved in a developing solution. Therefore, the exposed area is dissolved and removed with the developing solution, and the resist layer is patterned to form a resist. A pattern 201 is obtained.

Resin layer forming step (FIG. 2E): After the resist is cured, a resin layer 300 is formed on the recording surface of the master.
The material of the resin layer preferably has such a temperature characteristic that when the cured resist is heated, the resin layer also softens at a temperature at which the resist softens. For example, in the case of using a cresol novolak resin as a resist and a compound containing a diazonaphthoquinone derivative as a photosensitive agent,
Novolak resins, polyhydroxystyrene resins, acrylic resins, melamine resins, polyimide resins, polyvinylpyrrolidone resins, polyolefin resins, and the like can be used.

The resin layer 300 is formed by spin coating,
Dipping method, roll coating method, spray coating method,
It is preferable to carry out by a bar coating method or the like. This is because the resin needs to penetrate into every corner of the patterned resist.

Heating Step (FIG. 2F): After the resin layer 300 is formed, the resin layer 300 and the patterned resist 201 are all heated slowly until a constant temperature Ts is reached. The temperature Ts is determined by the composition of the resist and the resin layer as described above. If the temperature is set too high, the resist and the resin layer become too soft and the entire uneven shape is distorted. If the temperature is set too low, the resist and the resin layer are not sufficiently softened, and the surface roughness of the resist pattern cannot be sufficiently removed.

The heating time at the temperature Ts is set to 1 minute or more. If the length is shorter than this, the temperature will be lowered before the surface is sufficiently smoothed by the softening of the resist or the resin layer.

According to this heating step, the resist that has been patterned is softened by being heated to the temperature Ts. In addition, the resin layer surrounding it softens. When the material is softened, a distorted portion such as a surface unevenness is smoothed by a tension or the like acting on the material. Since the surfaces of both the resist and the resin layer are smoothed, the interface between the two layers is smoothed while the border is in contact. After the interface is smoothed, if the temperature of both layers is reduced, the layers harden while maintaining their shapes.

Removal Step (FIG. 2G): When the interface between the resist and the resin layer is smoothed, the temperature is lowered again to a temperature at which the resist is cured. After the interface is smoothed, the temperature of both layers is reduced, so that the layer is cured while maintaining its shape. That is, the surface roughness of the patterned resist is removed again.

Then, the resin layer 300 is removed with a solvent or the like. At this time, a solvent that completely dissolves the resin layer 300 but does not dissolve the resist is used. For example, alcohol, acetone, water and the like are preferable. In the resist 201 from which the resin layer has been removed, the roughness of the surface of the resist pattern is smoothed.

Etching Step (FIG. 2F): After the resist pattern 201 is formed, the recording surface of the master 100 is etched. Although there are a wet method and a dry method as an etching method, an optimum method and conditions may be selected in accordance with the material of the master 100 in terms of an etching sectional shape, an etching rate, in-plane uniformity, and the like. The dry method is superior in terms of the controllability of the etching. For example, parallel plate reactive ion etching (RIE), inductive coupling (ICP), electron cyclotron resonance (ECR), helicon wave excitation, magnetron, plasma etching, ion beam etching, etc. can be used. . In order to control the etching, conditions such as the type of the etching gas, the flow rate of the gas, the pressure of the gas, the bias voltage, and the like are changed. With this control, it is possible to perform etching into a desired shape, such as processing the etching into a rectangular shape or forming a tapered shape.

Resist Removal Step (FIG. 3A): After etching, the resist pattern is removed by dissolving in a solvent or ashing. Next, when the master is washed and dried, the stamper 1 as a mold is completed.

Molding resin layer forming step (FIG. 3B): An optical recording medium is manufactured using the stamper 1 manufactured as described above. A molding material is provided on the recording surface of the stamper 1,
The molding resin layer 400 is formed. When the injection molding method is used, polycarbonate is used as the molding material, and 2P
When a molding method is used, various resins such as an ultraviolet curable resin are used. For example, the molding resin layer 400 is formed by injection molding a polycarbonate resin or the like, or by photopolymerizing an ultraviolet curable resin or the like. When a polycarbonate resin is used, it is cooled and hardened after molding. When using UV curable resin,
The material is cured by irradiation with ultraviolet rays. Molded resin layer 400
Is molded into the outer shape of the optical recording medium. The concavo-convex pattern provided on the information recording surface of the stamper 1 is transferred to the molding resin or the like.

Peeling step (FIG. 3C): molding resin layer 400
When is cured, the molding resin layer 400 is peeled off from the stamper 1. The peeled molded resin layer 400 is the optical recording medium itself. Since no folds are formed on the side walls of the uneven shape formed on the stamper 1, no shape distortion occurs on the side walls of the pits of the optical recording medium copied from the stamper. Even when this optical recording medium is reproduced, unnecessary level fluctuation of the reproduced RF signal does not occur. For this reason, the original signal used for providing the concave and convex shape on the stamper 1 is reproduced as it is.

According to this embodiment, since the developed resist is once covered with the resin layer and then heated, the distortion generated in the outer peripheral shape of the pattern is removed by softening the material. In the stamper etched with the pattern from which the distortion has been removed, no folds are formed on the side walls of the uneven shape. Therefore,
Since the shape distortion does not occur on the side walls of the pits of the optical recording medium manufactured by the stamper, even if the optical recording medium is reproduced, the reproduced RF signal does not change in signal level. For this reason, the original signal used for providing the irregularities on the stamper is reproduced as it is.

[0042]

According to the present invention, there is provided a technique for manufacturing a mold in which irregularities are accurately formed according to the outer peripheral shape of the resist by removing the distortion of the outer peripheral shape of the patterned resist. A resin plate capable of restoring an original signal can be manufactured.

According to the present invention, by providing a combination of materials suitable for removing the distortion of the outer peripheral shape of a patterned resist, it is possible to manufacture a mold in which irregularities are accurately formed as in the outer peripheral shape of the resist. Provide technology,
Thus, a resin plate capable of restoring a correct original signal can be manufactured.

According to the present invention, by providing a temperature condition suitable for removing distortion of the outer peripheral shape of a patterned resist, a manufacturing technique of a mold in which unevenness is accurately formed as in the outer peripheral shape of the resist. To provide
A resin plate capable of restoring a correct original signal can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a master according to the present invention.

FIG. 2 is a sectional view of a stamper manufacturing process in which information is recorded on a master. A is an original master, B is a resist forming step, C is an exposing step, D is a developing step, E is a resin layer forming step, F is a heating step, G is a removing step, and H is an etching step after cleaning.

FIG. 3 is a cross-sectional view of a stamper manufacturing process in which information is recorded on a master, in which A is a stamper cross-sectional view, B is a molding resin layer forming process, and C is a peeling process.

FIG. 4 is a view for explaining the concavo-convex shape of a mold formed by a conventional resist.

FIG. 5 shows a conventional general stamper manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Stamper 101 ... Ridge part 102 ... Valley part 200 ... Resist layer 201 ... Exposed area 202 ... Unexposed area (resist pattern) 300 ... Resin layer 400 ... Molded resin layer for optical recording media

Claims (5)

[Claims] 1. A method of manufacturing a mold for manufacturing a resin plate for transferring a concave and convex shape formed on a recording surface of a master to a resin plate, comprising: a resist layer forming step of forming a resist layer on a recording surface of the master. An exposure step of exposing the resist layer formed on the recording surface of the master according to a predetermined pattern; a development step of developing the exposed resist layer; and a resin on the developed resist layer. A resin layer forming step of forming a layer, a heating step of heating the resist layer on which the resin layer is formed to a certain temperature Ts to soften the resist, and a step of heating the resist layer to a temperature at which the softened resist hardens again. Removing the resin layer from the resist layer after lowering the temperature of the resin layer. 2. The method according to claim 1, wherein the composition of the resin layer is selected so that the resin layer is softened at a temperature Ts at which the resist softens. . 3. The temperature Ts at which the resist softens is 1
The method according to claim 2, wherein the temperature is in the range of 00C to 300C. 4. The method according to claim 1, wherein the master is made of silicon or quartz. 5. A method of manufacturing a resin plate by using a mold manufactured by the method of manufacturing a mold for manufacturing a resin plate according to claim 1, wherein the uneven shape is formed. Providing a molding material on the recording surface of the formed mold, and peeling the cured resin plate from the mold after the molding material is cured.