JPH03280230A - Stamper for optical disk - Google Patents

Abstract

PURPOSE:To inexpensively produce the stamper which can produce optical disk substrates having high accuracy by subjecting the metallic thin film of the stamper having the metallic thin film formed with the rugged patterns corresponding to signals on a substrate to a vapor treatment by a silazane compd. CONSTITUTION:A photoresist of a positive type is uniformly applied on the glass substrate and is recorded and exposed with prescribed pit patterns by using an exposing machine; thereafter, the resist is subjected to development processing to obtain the resist patterns having desired ruggedness. After the thin film of metallic chromium is formed thereon, the excess resist and metallic thin film exclusive of the pattern positions are peeled away, by which the patterns consisting of the metallic chromium thin film are finally formed on the substrate. The stamper formed in such a manner is made to coexist together with the silazane compd. in a vessel made of glass or stainless steel, etc., and is held for >=5 minutes in the vapor atmosphere kept at the temp. ranging 100 to 250 deg.C by using an oven, etc., by which the stamper having the good peelability from the resin disk substrates to be reproduced is obtd.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a stamper for optical discs.

(Prior Art) Conventionally, a stamper for an optical disc has been manufactured as follows. That is, a pattern is formed by irradiating a photoresist film coated on a glass substrate with a laser beam, and then using this as a matrix, the nickel electroforming process is usually repeated several times to create a nickel product with the pattern transferred. Stampers have been manufactured and used. However, since this nickel stamper was manufactured using an electroforming method, stress was likely to occur, and the thickness was very thin at approximately 0.3 mm.
There was a problem in that the flatness of the disk was impaired due to non-uniform bending during molding and transfer.

On the other hand, as shown in Japanese Patent Publication No. 62-41852, for example, there is a method in which a flat disk substrate is obtained by directly etching grooves into a metal mold. However, this method has a problem in that it is very difficult to control the groove depth. In addition, precision polishing is required because steel such as Starpack steel is used, and furthermore, minute irregularities remain in the final stage, making it impossible to obtain a strictly flat surface. Furthermore, although the method of forming an etched thin film on a steel mold to obtain a concavo-convex pattern does not solve the problem of controlling the groove depth, minute concavities and convexities on the surface still remain. In addition, a new problem arises in that the adhesiveness between the steel surface and the thin film layer is poor and the concavo-convex pattern is likely to be missing.

Various methods other than those described above are known for producing the stamper itself, but basically it is common to go through several plating and peeling steps. but.

Such plating and peeling processes are complicated and troublesome operations that require skill, and repeating them increases the number of steps and prolongs the manufacturing time, resulting in cost problems and accuracy problems.

Furthermore, when an optical disc is molded using a metal plated thin plate as a stamper, non-uniform bending tends to occur during molding, resulting in another problem in terms of accuracy in that the wall thickness of the duplicate disc becomes non-uniform.

Furthermore, thermoplastic resins (polycarbonate, acrylic,
When using polyolefin (such as polyolefin), injection molding or injection compression molding is the main method. The means for separating the stamper and the resin disk substrate during molding is as follows:
This problem was solved by incorporating an internal mold release agent into the resin raw material. For this reason, it was excellent in mass production, but the drawback was that
Problems include being susceptible to birefringence, resulting in poor optical uniformity, and poor adhesion to recording films and the like.

In addition, in a method for manufacturing a reproduction mold for video frequency signal recording disclosed in Japanese Patent Application Laid-open No. 51-35308, a stamper is manufactured by a so-called lift-off method, and the stamper is used to hot-press a thermoplastic resin. A method for manufacturing a reproduction disc is described. Stampers made by the lift-off method are inflexible and brittle, so there is a risk of breakage during injection molding or injection compression molding. The stamper is prevented from being damaged. Furthermore, since thermoplastic resin is used, heating and cooling may have to be repeated, and the molding speed of the duplicator is slower than in the past, resulting in low productivity.

On the other hand, when using the so-called 2P molding method, heat or photocurable resin (epoxy, acrylic, silicone, etc.)
was used as a substrate for optical discs, and there were no problems with birefringence, but the stamper and resin discs were similarly made by adding an internal mold release agent to the resin or changing the composition to reduce the polar groups in the resin. The aim is to improve releasability from the substrate.

If such mold release measures are not taken, the stamper and the resin disk substrate will stick to each other during molding, making it difficult to recover both, or forcing the stamper and the resin disk substrate to separate may cause damage or cracking, which is a troublesome problem. There was a problem. Furthermore, if a mold release agent is added to the resin itself to give it a mold release effect, the reflective film and recording film provided on the disk substrate in a later process will easily peel off, resulting in a decrease in adhesion to these films, or the recording film will be removed. There was a problem that wrinkles and cracks appeared on the paper, resulting in deterioration.

(Problems to be Solved by the Invention) As mentioned above, conventional stampers cannot be easily manufactured, and when an optical disk substrate is molded using the stamper, there is a noticeable problem of peeling from the resin disk substrate. .

The present invention has been made to solve these problems, and an object of the present invention is to provide an optical disc stamper that can be manufactured at low cost and that can reproduce and manufacture optical disc substrates with high precision.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a stamper for an optical disc including a metal thin film formed on a substrate with a concavo-convex pattern according to a signal, wherein the metal thin film is made of a silazane compound. This is an optical disc stamper characterized by being subjected to steam treatment.

The stamper for optical disks of the present invention uses a material whose surface can be processed and maintained flat with high precision, such as glass, quartz, or ceramic, as a substrate, and has uneven pits or groups corresponding to the information to be recorded on the substrate. It is formed of metallic chromium, metallic titanium, or the like by a lift-off method. The thickness of the substrate at this time is preferably at least 1 mm from the viewpoint of ease of handling and strength.

Next, we will explain an example of the manufacturing process of the stuncoat for optical discs of the present invention. First, a photoresist layer is uniformly applied onto the substrate using a spinner or the like. The film thickness of this photoresist is determined by defects such as pinballs and comments. A value of 1000 A or more is desirable as it reduces the generation of heat and increases chemical resistance.

Next, the resist is exposed to laser light and developed.

Furthermore, a metal thin film is formed using metallic chromium or metallic titanium on the developed resist pattern. The thickness of this metal thin film is approximately 100OA to 150OA, since a good v1 of about λ/4 is determined by the relationship with the wavelength of the laser beam during reading.
0A is appropriate. Taking this into consideration, it is appropriate for the resist film thickness to be in the range of about 1000A to 3000A. Furthermore, metallic chromium and metallic titanium are materials that can be formed into thin films by vacuum evaporation or sputtering and have good adhesion to the substrate material.

Thereafter, by peeling off the excess resist and metal film, uneven information (pits or group patterns) of metal chromium or metal titanium remains on the substrate, and finally a stamper can be manufactured.

The resist can be easily removed by immersing the resist in an organic solvent such as acetone. At this time, excess metal chromium or titanium deposited on the resist can also be removed at the same time.

In the present invention, the stamper is preliminarily coated with hexamethyldisilazane, N-trimethylsilylacetamide, dimethyltrimethylsilylamine, diethyltrimethylsilylamine, or trimethylsilylimidazole in order to facilitate the separation between the stamper and the resin disk substrate to be replicated during molding. It has been found that steam treatment with at least one silazane compound selected from the following is particularly effective, and it is no longer necessary to incorporate a mold release agent into the molding resin material as in the past.

A specific steam treatment method using a silazane compound is as follows:
A small amount of the above-mentioned silazane compound and the stamper prepared as above are placed in a container made of glass or stainless steel, etc., and the temperature is set in the range of 100 to 250°C using an oven or the like. This can be achieved by holding it for more than a minute.

It should be noted that processing can be performed at temperatures above room temperature, but at low temperatures the processing time becomes longer than several tens of minutes. In addition, when the temperature reaches 250° C. or higher, it tends to cause problems in handling, which lowers efficiency in terms of production costs. In addition, since the steam processing capacity of silazane compounds is usually 300 to 400 i/g, the amount used each time is as small as 0.1 g/l, which is excellent from an economic standpoint. It can be called processing.

This peeling treatment only needs to be performed once after the standbar is produced and before it is used for molding, and there is no need to perform the peeling treatment every time it is molded.

The present invention will be explained in detail below based on examples.

(Examples) Example 1 First, a positive photoresist (Tokyo Ohka Layer TSMR-8800) was uniformly coated to a film thickness of 2000 Å using a spinner on a glass substrate with a diameter of 130 mm and a thickness of 5+ am.

Next, a predetermined pit pattern was recorded and exposed using an exposure machine, and then developed with an alkaline developer to obtain a resist pattern having a desired uneven shape.

Furthermore, a thin film of metallic chromium having a thickness of 1200 Å was formed on this resist pattern by vacuum evaporation.

After that, using acetone, the excess resist and metal chromium thin film other than the pattern position are peeled off and finally a pattern made of the metal chromium thin film is formed on the substrate,
Using this as a stamper, six more similar stampers were produced.

Next, this stamper was subjected to steam treatment as follows.

As a silazane compound, hexamethyldisilazane, N-
Select five types: trimethylsilylacetamide, dimethyltrimethylsilylamine, diethyltrimethylsilylamine, and trimethylsilylimidazole, and add about 0.5 of the above silazane compound to each separately in a stainless steel container.
g, and put the stamper sheets prepared as above into each container. Use an oven to warm these containers to a temperature of 120°C, maintain this state for about 15 minutes, and then let it cool naturally. Each stamper was then subjected to steam treatment.

On the other hand, as a comparative example, a stamper was prepared in which the silazane compound was not subjected to steam treatment.

An attempt was made to produce an optical disc substrate (duplicate disc) using these stampers.

First, a vinyl group-containing silicone resin (
After applying Toshiba Silicone YR-3224).

It was dried at 110°C for 10 minutes.

Next, the stamper was pressed onto a vinyl group-containing silicone resin on a glass substrate, heated at 180° C. for 1 minute to cure the silicone resin, and then the stamper was peeled off to obtain an optical disk substrate. As a result, the stamper treated with the five types of silazane compounds described above could be easily separated from the optical disk substrate during molding. Thereafter, the same process was repeated 50 times, and 50 optical disc substrates (duplicates) were obtained without any problems.

On the other hand, in the comparative example of molding using a stamper that was not subjected to vapor treatment of the silazane compound, the optical disc substrate and the stamper stuck to each other during molding and could not be separated. When both of them tried to forcefully peel it off, the glass substrate coated with silicone resin broke.Example 2 A surface-polished alumina plate (diameter 130+am, thickness 10cm) was prepared as a stamper substrate material. A stamper was produced in the same manner as in Example 1, except that a pit pattern of a metallic titanium thin film was formed by the usual RF sputtering method.

Next, the stamper was steam-treated in the same manner as in Example 1, except that hexamethyldisilazane was selected as the silazane compound, the temperature was raised to 100° C., and the stamper was held in this steam atmosphere for 15 minutes. Next, using this stamper, Example 1
An attempt was made to fabricate a replica disk by molding a silicone resin substrate in the same manner as in Example 1. As a result, molding and peeling were possible without any problems as in Example 1.

Furthermore, when the molded duplication disks were observed under a microscope, it was found that there was no problem in the transferability of pit patterns in both Examples 1 and 2.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a stamper with good releasability and which can reproduce and manufacture optical disc substrates with high precision.

Claims (2)

[Claims] (1) An optical disk stamper comprising a metal thin film formed on a substrate with a concavo-convex pattern according to a signal, characterized in that the metal thin film is subjected to a vapor treatment using a silazane compound. Stamper for optical discs. (2) Steam treatment with at least one silazane compound selected from hexamethyldisilazane, N-trimethylsilylacetamide, dimethyltrimethylsilylamine, diethyltrimethylsilylamine, and trimethylsilylimidazole (1)
) stamper for optical discs.