JPH02290991A - Production of stamper - Google Patents

Abstract

PURPOSE:To produce a stamper hardly causing noise and having superior properties by carrying out neutralization with a dil. acid soln. and washing after alkali development in a process for producing a stamper for producing a substrate for an optical recording medium such as a compact disk or a magneto- optical disk. CONSTITUTION:The optically polished surface of a glass substrate is coated with a positive type photoresist and this resist is exposed with a laser beam cutting machine and developed with an alkali developing soln. to form a group of pits, etc. The used alkali developing soln. is neutralized with an acid soln. having a lower normality than the alkali developing soln., e.g. dil. sulfuric acid and washing with pure water is carried out. The substrate is then made electrically conductive by sputtering Ag, Ni, etc., and Ni is electrodeposited. The resulting electrodeposited layer is separated from the glass master to produce a high quality stamper hardly causing noise for a substrate for an optical recording medium such as a compact disk.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a stamper for mass-producing optical recording substrates such as compact discs (hereinafter referred to as CDs) and magneto-optical discs. be.

[Summary of the Invention] The present invention provides a method for manufacturing a stamper for duplicating a substrate for an optical recording medium, in which a photoresist is coated on the surface of an optically polished glass substrate, the resist is exposed to light using a laser cutting machine, and then an alkaline solution is applied. In the process of developing a glass master by forming predetermined pits, groups, etc., the alkali content of the glass is removed by developing with an alkaline solution and immediately neutralizing and cleaning the glass master surface with a dilute acid solution. This prevents stains on the finished stamper surface due to residue on the master surface, and also reduces noise by improving the surface condition.

[Prior art] The conventional method for manufacturing a stamper for duplicating optical recording substrates is to uniformly apply photoresist to the required thickness by spin coating on the surface of a polished glass substrate, blurpake, and then expose to light using a laser cutting machine. Arbitrary pits or groups are formed by developing with an alkaline solution and dissolving the exposed areas.

After sputtering silver or nickel onto this glass master to make it conductive, nickel electroforming is applied to approximately 300μ, and then the back side is polished to a more uniform thickness.The nickel electroformed layer is then peeled off from the glass master and the inner and outer surfaces are removed. The stamper is completed after diameter processing and cleaning.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, in the development process, the exposed portion is only washed with water after dissolving with an alkaline solution, so it is difficult to completely remove the alkaline content, and the glass master must be spun. There is a high possibility that stains will appear on the surface of the master disc after it dries, and stampers that are manufactured by transferring from this master disc are
Furthermore, such stains generated during development are transferred to the molded substrate, causing problems in appearance.

Furthermore, when the microscopic surface condition of the groups formed by development tends to become rough when washed only with water, the final product disk has high noise, which affects the reduction of the C/N ratio.

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing an optical recording stamper of the present invention involves coating the surface of a glass substrate with a photoresist, exposing the resist to light using a laser cutting machine, and then developing it. The glass master on which pits, groups, etc. have been formed is subjected to sputter conductivity treatment with silver, nickel, etc., and after nickel electroforming, the electroformed layer is peeled off from the glass master, and in the process of manufacturing a stamper for substrate duplication, alkaline development It is characterized in that after the processing step, it is neutralized and washed with a diluted acid solution, and that the concentration of the diluted acid solution used in the neutralized washing is less than the normality of the alkaline solution used in the development processing step.

[Function] According to the present invention, by neutralizing and cleaning with a dilute acid solution after alkaline development treatment, alkaline components that are difficult to completely remove with ordinary pure water cleaning are removed from the glass master surface through a neutralization reaction. It can be completely removed, and it is possible to eliminate the stains on the surface of the finished stamper that were previously caused by residual alkaline content, as well as to improve the microscopic surface condition of the groups formed by development. It was possible to improve the C/N ratio by reducing noise in the final completed disc.

[Example] A positive photoresist (
Az1350 (manufactured by Hoechst) was coated to a thickness of 1,300 mm, and then 2 coated using a laser cutting machine.
The resist is exposed by beam and halftone cuts.

Next, after developing with a 0.3N (normality) alkaline developer (AZ developer: manufactured by Hoechst) to form pits, groups, etc., immediately neutralize and wash with a 0.2N diluted sulfuric acid solution, and then wash with pure water. After cleaning and finally spin-drying the glass master, perform nickel electroforming after conductive treatment with nickel back. This electroformed layer is peeled off from the glass master, the back surface is polished, the inner and outer diameters are machined, and the resist is removed and washed to form a φ130 beam. Completed as a memory stamper.

Using these process conditions, we were able to continuously manufacture stampers and completely eliminate the stains on the stamper surface that had previously occurred with a probability of 20 to 60%, greatly improving the yield of stampers. I was able to do it.

Furthermore, using this stamper, substrate molding, Tb-Fe
- When we deposited a Co-based media film and measured the C/N ratio of the completed optical disc, we found that the noise was reduced compared to conventional discs, and the CZN ratio was improved by 2 to 3 dB. We were able to improve quality.

[Effects of the Invention] As described above, in the stamper manufacturing process, the present invention neutralizes and washes with a dilute acid solution after the alkaline development process, thereby removing alkaline content that is difficult to remove with normal washing alone. It can be completely removed from the glass master surface, eliminating stains on the finished stamper surface caused by residual alkali content, and smoothing the microscopic surface condition of the groups formed by development. It has also become possible to improve the C/N ratio by reducing noise in the final completed disc.

Note that similar effects can be obtained with inorganic acids and organic acids other than those used in the examples.

In the present invention, the concentration of the dilute acid solution for neutralization cleaning is specified because if the acid concentration is too high than the specified 4 degrees of alkaline developer, adverse effects such as bottle holes in the conductive film due to residual acid content may occur. Therefore, the concentration of the dilute acid solution was set to be below the specified concentration of the alkaline solution used in development.

that's all Applicant Seiko Epson Corporation Representative Patent Attorney Kisaburo Suzuki (and 1 other person)

Claims (1)

[Claims] 1) Sputter conductive treatment with silver, nickel, etc. on a glass master in which the surface of a glass substrate is coated with a photoresist, the resist is exposed with a laser cutting machine, and then developed to form pits, groups, etc. A method for producing a stamper, which comprises, after electroforming nickel, peeling off the electroformed layer from a glass master to produce a stamper for substrate duplication, which is characterized by neutralizing and cleaning with a dilute acid solution after an alkaline development process. 2) The stamper manufacturing method according to claim 1, wherein the concentration of the dilute acid solution used for neutralization and cleaning is lower than the normality of the alkaline solution used in the development process.