JP2003067985A - Metal die for molding optical disk and optical disk made by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of optical disk manufacturing by providing an optical disk metal die which is easy to make in a short time and resistant even to injection molding with molten resin. SOLUTION: A metal die 4 having a concavo-convex pattern is made by forming a resin layer 2 on the surface 1A of a metal die blanc 1 using a photosensitive polyimide system heat resistant resin, exposing it through a mask pattern 3 matching the optical disk signals and developing it to form convex pits 2A and 2A and to obtain cured convex pits 2B and 2B by heating. When forming an optical disk using this metal die 4, the concavo-convex pattern is reverse transferred to obtain an optical disk having a pattern matching the optical disk signals of high density, high resolution and high reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk molding die and an optical disk molded using the same.

[0002]

2. Description of the Related Art Generally, an optical disc is injection-molded or press-molded from a transparent resin such as a methacrylic resin or a polycarbonate resin by using a nickel mold called a stamper on which a fine concavo-convex pattern corresponding to an optical disc signal is formed. It is manufactured by transferring a fine concavo-convex pattern on the stamper to the resin surface by the method described above. Then, a stamper for an optical disc is conventionally manufactured through the following complicated steps.

(1) First, residual nickel, residual resist, etc. are removed from a used glass plate and the surface thereof is polished to regenerate the glass plate. (2) The reclaimed glass plate is cleaned by a method such as ultrasonic cleaning to remove the polishing agent and the like remaining on the surface. (3) Next, after drying this glass plate, a photoresist is applied to the surface thereof to form a photoresist layer. (4) Subsequently, a desired optical disk signal is exposed and recorded by laser light on the photoresist layer of this glass plate. (5) By developing this, an uneven pattern corresponding to the above-mentioned optical disc signal is formed on the photoresist layer. (6) Next, a thin metal layer is formed on the surface of the photoresist layer by a method such as sputtering, vapor deposition, electroless plating (metallization). (7) A nickel plating layer is formed by plating (electroforming) the upper surface of this metal layer to a predetermined thickness. (8) After that, the stamper part consisting of the metal layer and the plating layer is peeled off from the glass plate, and then the photoresist and the like adhering to the pit surface of the stamper part is washed away,
Post-processing such as drying and removing an excessive portion with a press is performed to obtain a stamper mainly composed of nickel.

However, the production of such a stamper requires a very long process and requires a lot of equipment, resulting in a large amount of equipment investment and, accompanying this, a large clean room area. There was a problem. In addition, since the raw material cost, running cost and time required for manufacturing are large, the unit price is high, and the manufacturing process is difficult individually, and the manufacturing process requires experience and know-how in each manufacturing process. There was also the problem that it was difficult.

As one of means for solving such a problem,
For example, in Japanese Unexamined Patent Publication (Kokai) No. 3-65326, Si on a glass master is used.
A method of manufacturing a stamper by so-called 2P (Photopolymer) molding in which a fine concavo-convex pattern corresponding to an optical disc signal formed through an O ₂ layer is copied onto a translucent substrate through an ultraviolet curable resin is disclosed. There is. That is, according to the method described in this publication, SiO ₂ is formed on the glass master.
Layers and a photoresist layer are sequentially formed, a desired optical disc signal is exposed and recorded thereon, and then developed, and then the SiO ₂ layer is etched using the remaining resist layer as a mask, and then the remaining resist layer is removed. the ultraviolet curable resin is applied to the SiO ₂ layer fine uneven pattern is formed, by pressing a light-transmitting substrate thereon, SiO ₂
Filling an ultraviolet-curing resin between the layer and the transparent substrate, irradiating ultraviolet rays through the transparent substrate to cure the ultraviolet-curing resin, and copying the fine concavo-convex pattern based on the above optical disc signal to the transparent substrate. To form a stamper.

This method has the advantage that the stamper can be manufactured in a small number of steps, but when etching using the resist layer as a mask, reactive ion etching equipment is required and the SiO ₂ layer is formed to a predetermined depth. In addition, it is difficult to control etching, which makes it difficult to manufacture the stamper inexpensively and easily. Further, in this publication, the stamper obtained as described above is used as a work stamper for sol-gel. When this stamper is applied to injection molding of a molten resin, the molten resin to be injected is a UV-curable resin, Affected by the heat of
The pattern is deformed early.

Further, in Japanese Unexamined Patent Publication No. 8-255383, after coating a negative type photoresist on a mirror-like substrate, an optical disc signal is exposed and recorded on the photoresist layer and then developed to develop an optical disc on the mirror-like substrate. An optical disc is formed on the photoresist layer by forming a fine pattern of the photoresist layer based on a signal and curing the photoresist pattern on the mirror substrate thus formed, or after applying a positive photoresist on the master. The signal is exposed and recorded, and then developed to form a fine pattern of a photoresist layer corresponding to the optical disc signal on the master,
After the photoresist pattern formed in this way is cured, the mirror-like substrate is brought into close contact with this pattern through an ultraviolet-curing resin, and then the ultraviolet-curing resin is cured to copy the above pattern onto the mirror-like substrate, thereby replacing the stamper. A method of manufacturing the direct recording medium for optical disc has been proposed.

Although it is expected that the method described in this publication can also be used to manufacture a direct recording medium for an optical disk that substitutes for a stamper with a small number of steps, this publication discloses specific examples of the photoresist and the ultraviolet curable resin to be used. When using a direct recording medium manufactured by this method for molding an optical disk using a photoresist that is used in the ordinary optical disk, there is no regulation, especially in injection molding, the heat of the molten resin injected is There is a problem that the pattern based on the optical disc signal is deformed under the influence of.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above points, and its object is to:
We provide a mold for optical disk molding that can be easily manufactured in a few steps, and therefore in a short time, and is also resistant to injection molding from molten resin. Furthermore, using it, an optical disk can be easily manufactured. To do.

[0010]

[Means for Solving the Problems] As a result of research conducted in accordance with the above problems, a photosensitive heat-resistant resin was applied onto a mold substrate, and a transparent and light-shielding pattern corresponding to an optical disk signal was formed thereon. By using the photoresist technique of exposing through the formed mask pattern and developing, a molding pattern is directly formed on the mold substrate and baked at a high temperature, so that even if the high-temperature molten resin is injected and filled, It has been found that a mold which is not deformed and can be replaced by the nickel stamper according to the conventional method can be easily manufactured in a short time.

Therefore, according to the present invention, there is provided a molding die for integrally forming an optical disc signal on one surface of an optical disc, in which a die substrate and a transmission and light shielding pattern corresponding to the optical disc signal are recorded. Provided is a molding die for an optical disc, which is provided with a signal element composed of a fine protruding pattern of a photosensitive heat-resistant resin directly formed on the die substrate by a photoresist method through a mask pattern.

Further, according to the present invention, there is provided an optical disc having a surface on which a fine concavo-convex pattern corresponding to an optical disc signal is integrally formed, wherein the concavo-convex pattern is recorded with a transparent and light-shielding pattern corresponding to the optical disc signal. Also provided is an optical disc in which a fine projection pattern of a photosensitive heat-resistant resin is formed directly on a die substrate by a photoresist method through a mask pattern, and the optical disc molding die is further provided. There is also provided a method of manufacturing an optical disc by using a mold and transferring the protruding pattern of the mold onto the surface of a transparent resin.

In the present specification, the photoresist method is a method adopted for patterning using a photoresist in the semiconductor field or a method similar thereto, and a photoresist film is formed on a mold substrate, It is used as a term meaning a method of transferring the shape of the mask pattern used for the exposure to the mold substrate by exposing through the mask pattern and then developing.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the examples shown in the drawings. FIG. 1 is a vertical cross-sectional schematic diagram showing each manufacturing process of an optical disk molding die according to the present invention. As shown in FIG. 1A, first, a photosensitive heat resistant resin is applied on the surface of the mold substrate 1 to form a photosensitive heat resistant resin layer 2. At least the surface 1A of the mold substrate 1 on which the photosensitive heat-resistant resin layer 2 is formed is a smooth mirror surface. Next, as shown in FIG. 1B, the photosensitive heat-resistant resin layer 2 is exposed to ultraviolet rays (UV light) through a mask pattern 3 on which a transparent and a light-shielding pattern based on a desired optical disc signal is recorded. After that, develop it and
As shown in (C), the convex pits 2A made of the photosensitive heat-resistant resin remaining in the pattern based on the optical disk signal are formed on the one surface 1A of the mold substrate 1. After that, the convex pits 2A formed on the one surface 1A of the mold substrate 1 are
The cured convex pits 2B shown in FIG. 1D are obtained by baking at a high temperature of 0 ° C. or higher and curing. Through the above steps, the molding die 4 for an optical disc can be obtained in which the cured convex pits 2B are arranged on the one surface 1A of the die substrate 1 in a pattern based on the above-mentioned optical disc signal. The cured convex pits 2B thus formed on the mold substrate 1 and the mold substrate 1
The concavo-convex pattern based on the exposed surface 1A of FIG. The molding die 4 for this optical disk is set on the mold surface, and moldings that are usually adopted such as injection molding or press molding using a suitable thermoplastic resin, or so-called 2P (Photopolymer) molding using an ultraviolet curable resin. An optical disk can be manufactured by performing the processing.

The mold substrate 1 may be of any type as long as it can be used as a mold for molding a thermoplastic resin or the like, and the material is not particularly limited. For example, a stainless steel plate or a normal optical disk stamper manufacturing process. A mirror surface plate made of nickel or the like, which is obtained by sequentially subjecting the cleaned glass plate or the resist-coated glass plate used in 1) to conductive treatment and electroforming, is preferably used. The thickness is also not particularly limited, but it is easy to handle, etc.
A thickness of about 1 to 5 mm is suitable.

In the present invention, the photosensitive heat-resistant resin for forming the photosensitive heat-resistant resin layer 2 is, for example, in the semiconductor field,
In particular, it has applications such as a protective coating film for semiconductor wafers and interlayer insulating film, and has high resolution by exposure and development and high adhesion by baking. Therefore, by the photoresist method, a fine pattern based on a fine, precise and high density optical disc signal can be surely formed directly on one surface 1A of the mold substrate 1 as a pattern of fine protrusions. Further, the molding of the optical disk is made as easy and reliable as possible, and due to the high degree of adhesion, partial peeling from the one surface 1A of the mold substrate 1 is prevented as much as possible, and a molding mold for mass production of optical disks. Assuring durability.

In the illustrated example, the photosensitive heat-resistant resin is a positive type, and the portion shielded from light by the mask pattern 3 in FIG. 1B is, after development, the convex pit 2 shown in FIG. 1C.
The portion remaining as A and exposed through the opening of the mask pattern 3 is configured to be dissolved and removed by development. In this example, the positive photosensitive heat-resistant resin is a polyimide-based resin, and the positive photosensitive polyimide-based resin is, for example, a semiconductor coating material "SUMIREZIN EXCEL manufactured by Sumitomo Bakelite Co., Ltd."
CRC-8000 ”series, specifically, for example, CRC
-8300 can be used.

To form a molding pattern on the mold substrate 1 using such a positive photosensitive heat-resistant resin, for example, the positive photosensitive heat-resistant resin is applied to the mold substrate 1 and a photoresist film is formed on the surface. A coating step of forming, a pre-baking step of pre-heating this and performing light baking, and a resin applied as described above, that is, the photosensitive heat resistant resin layer 2 (photo The resist film) is exposed (may be referred to as exposure), the developing process for developing it, the washing process for rinsing the removed portion by development, and the pattern formed by development are baked at high temperature. It can be performed by curing the positive photosensitive heat-resistant resin and baking it to form the cured convex pits 2B.

In the coating step, for example, by using a spin coater (rotary coating machine), a positive photosensitive heat-resistant resin is dropped or sprayed on the surface 1A of the mold substrate 1 set on the spin coater, that is, the molding surface. It is supplied, the mold substrate 1 is rotated at a high speed, and the positive photosensitive heat-resistant resin is applied to the optical disk signal to a uniform thickness of, for example, about 5 μm or less, so that the photosensitive heat-resistant resin is applied. The resin layer 2 may be formed.

In the pre-baking step, using a heating furnace, the pre-baking step is carried out by placing it in an atmosphere heated to, for example, about 120 ° C. for several minutes,
The photosensitive heat resistant resin layer 2 is lightly baked. This ensures accurate and high-density exposure in the exposure process.

In the exposure step, for example, a stepper (exposure machine) is used, and the photosensitive heat-resistant resin layer 2 is exposed to the g-line, i-line or the like through the mask pattern 3 on which a pattern based on the optical disc signal is formed. It can be performed by irradiating with a continuous wavelength light source including for a short time. As a light source that emits continuous wavelength light including ultraviolet rays, for example,
A high pressure mercury lamp can be used. At this time, in this example, the mask pattern 3 masks the portion corresponding to the convex pit 2A of the molding pattern, and irradiates the non-mask portion with the light source light to expose it. .

In the developing step, for example, a developer (developing machine) is used to set the mold substrate 1 having the exposed photosensitive heat-resistant resin layer 2, and a resist developing solution which is an alkaline aqueous solution is dropped onto the mold substrate 1. It is supplied by spraying or the like, and the mold substrate 1 is rotated or stopped to uniformly distribute the developing solution, and the developing solution is permeated into the exposed non-mask portion other than the fine projection portion 2A to dissolve it. Is done like.

The cleaning step is carried out, for example, by rotating the mold substrate 1 after development at a high speed and supplying pure water thereto by dripping or spraying to rinse away the dissolved portion.

In the subsequent baking step, using a heating furnace, for example, the mold substrate 1 having the above-mentioned cleaned convex pits 2A in a nitrogen atmosphere heated to about 300 to 400 ° C.
Is placed to harden the pattern formed by development and fix the pattern on the mold substrate 1 in close contact to form a molding pattern corresponding to an optical disc signal.

By doing so, a molding pattern (curing convex pit) 2B obtained by reversing the pattern based on the optical disk signal is directly formed on the mold substrate 1, and the curing convex pit 2B for the mold substrate 1 is formed. It is possible to obtain a molding die 4 that ensures a high degree of adhesion and is suitable for molding an optical disc.

Molding of an optical disk using the molding die 4 is performed, for example, by setting the die 4 in a molding machine such as an injection molding machine and performing the molding at a molding temperature suitable for the thermoplastic resin used. Good. When an optical disc is manufactured by so-called 2P molding, an ultraviolet curable resin is applied to the surface of the mold 4 on which the convex pits 2B are formed, a transparent substrate is pressed against the resin, and the transparent substrate side is pressed. It suffices to irradiate ultraviolet rays to cure the ultraviolet curable resin and take out the optical disk made of the cured resin. By any of these methods, the cured convex pits 2A formed on the molding die 4
The uneven pattern based on is transferred to the surface of the transparent resin.

The molding die of the present invention is preferably used in a method for producing an optical disk by injection molding a transparent thermoplastic molten resin. As the thermoplastic resin used for forming the optical disc, for example, a transparent synthetic resin having a high light transmittance such as methacrylic resin, polycarbonate resin, amorphous polyolefin resin, methyl methacrylate / styrene copolymerization (MS) resin is suitable. Used. The same resin is used also when manufacturing an optical disk by press molding.

Although the illustrated example is as described above, the photosensitive heat-resistant resin is a negative type, and the portions exposed through the mask pattern are left as convex pits, which are used as protruding patterns corresponding to optical disc signals. You can also do it. The negative photosensitive heat-resistant resin is also preferably a polyimide resin, such as "PI-2732" manufactured by Hitachi Chemical DuPont Micro Systems Co., Ltd.

In addition, the formation of the photoresist film 2 of the photosensitive heat-resistant resin on the mold substrate 1 including the coating of the mold substrate 1 with the photosensitive heat-resistant resin solution by dipping is also included in the present invention. In the implementation, the mold substrate, signal elements formed on the surface thereof in correspondence with the optical disc signal, each specific material such as photosensitive heat-resistant resin, shape, structure, production or manufacturing method or its process, density, viscosity, size The arrangement, the form of the arrangement, the use, addition to these, and the like can take various forms as long as they do not violate the gist of the invention.

[0030]

Since the present invention is constructed as described above,
It is possible to simplify the manufacturing of optical disk molding dies as much as possible, greatly reduce the manufacturing time, for example, to several hours, and accurately respond to short-term production of optical disks, while ensuring accuracy and durability. It is possible to provide a molding die for an optical disc, which can lead to a reduction in the production cost of the optical disc. The photosensitive heat-resistant resin may be either a positive type or a negative type, and can be a molding die having a molding pattern corresponding to a preferable optical disc signal. The preferred form of the photosensitive heat-resistant resin is a polyimide-based resin, and by using this, it is possible to directly and easily form a molding pattern by the photoresist method, and it also has transferability when molding an optical disk. Can be a molding die. Then, by using the molding die of the present invention, it is possible to manufacture an optical disc on which a fine concavo-convex pattern corresponding to an optical disc signal is accurately transferred.

[Brief description of drawings]

FIG. 1 shows a molding die for an optical disk according to the present invention,
It is a longitudinal cross-sectional schematic diagram shown for every manufacturing process.

[Explanation of symbols]

1 ... Mold substrate, 1A ... One side surface which is a mirror surface of the mold substrate, 2 ... Photosensitive heat-resistant resin layer, 3 ... Mask pattern, 2A: convex pit (photosensitive heat-resistant resin remaining after development), 2B ... Curing convex pit, 4 ... Optical disk molding die.

Claims (6)

[Claims] 1. A molding die for integrally forming an optical disc signal on a surface of one side of an optical disc, the die substrate comprising:
A signal element consisting of a fine projection pattern of a photosensitive heat-resistant resin formed directly on the mold substrate by a photoresist method through a mask pattern on which a transparent and a light-shielding pattern corresponding to an optical disc signal is recorded. A molding die for an optical disk, which is characterized in that 2. The optical disk according to claim 1, wherein the photosensitive heat-resistant resin is a positive type, and a signal element corresponding to an optical disk signal is formed in a protruding manner on a mold substrate by exposure and development through a mask pattern. Molding dies. 3. The optical disk according to claim 1, wherein the photosensitive heat-resistant resin is a negative type, and a signal element corresponding to an optical disk signal is formed in a protruding manner on a mold substrate by exposure and development through a mask pattern. Molding dies. 4. The molding die for an optical disc according to claim 1, wherein the photosensitive heat-resistant resin is a photosensitive polyimide resin. 5. An optical disc in which a fine concavo-convex pattern corresponding to an optical disc signal is integrally formed on the surface, wherein the concavo-convex pattern is provided through a mask pattern on which a transmission and a light shielding pattern corresponding to the optical disc signal are recorded. An optical disk characterized in that a fine projection pattern of photosensitive heat-resistant resin is formed from a mold directly formed on a mold substrate by a photoresist method. 6. A method of manufacturing an optical disk, which comprises using the optical disk molding die according to claim 1 and transferring the protrusion pattern of the optical disk onto the surface of a transparent resin.