JPS61284844A - Production of master disk for optical disk - Google Patents

Abstract

PURPOSE:To improve the reliability of a master disk and to extend the life thereof by forming a glass master disk, then forming a thin metallic film different from a material to be used for a plating treatment on the glass master disk, subjecting the film to the plating treatment to form a plating film and removing the thin metallic film so that the master disk is constituted of only the plating film. CONSTITUTION:A photoresist 8 is coated on a glass substrate 7 and thereafter laser light 9 corresponding to a digital signal is recorded thereon. The photoresist is developed and the glass master disk provided with a digital signal part 10 is formed. The thin metallic film 13 of Al which is a material different from Ni, i.e., the plating material to be used for the plating treatment of the next stage is then provided by a method such as vapor deposition on the glass master disk. The plating film 12 of Ni is formed by an electroplating method on the film 13. The thin metallic film 13 of Al is removed by a chemical etching method for immersing the composite base material provided with the film 13 and the plating film 12 into an aq. NaOH soln. which is a weak alkaline soln. The master disk for an optical disk formed of only the plating film 12 of Ni is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention records digital signals such as video discs, digital audio discs (such as compact discs), still images and document files.

The present invention relates to a method for manufacturing an optical disk master for manufacturing a reproducible or erasable optical disk.

2. Description of the Related Art Optical discs of this type have extremely high information density, a high S/N ratio, and low noise, making them promising as information media, and they have been commercialized as video discs and digital audio discs, and digital In recent years, it has been researched and developed as an optical disc that can record, play, and erase data.

FIG. 3 shows an overview of a compact disc, which is a conventional general digital audio disc.

In this system, a PGM-converted digital signal is recorded in a focused line on a resin substrate and reproduced by a semiconductor laser.

In FIG. 3, 1 is a disk, 2 is a resin substrate, 3 is a digital signal part in the form of a pit row carved on the resin substrate 2, and 4
6 is a reflective film formed on the surface thereof, 6 is a protective film coated on the reflective film 4, and 6 is a semiconductor laser beam for reproduction.

The resin substrate 2 is generally mass-produced using a molding method such as injection molding or injection/compression molding. Master disk for optical disc is resin substrate 2
It is necessary for obtaining a mold by molding, and is attached to the mold.

FIG. 2 shows a conventional method for manufacturing an optical disk master. FIGS. 2a to 2f are cross-sectional views showing each step. A photoresist 8 is applied to a glass substrate 7, a digital signal is recorded by a laser beam 9, and a digital signal portion 1o is formed by development.

Next, a metal thin film 11 such as nickel (Ni) is formed by vapor deposition, and a plating film 12 is formed thereon by nickel (Ni) plating. Thereafter, by peeling off the glass substrate 7, an optical disc master is formed.

Problems to be Solved by the Invention However, since the metal thin film 11 of nickel (N1) on the signal surface of the optical disk master obtained with the above configuration is formed by a method such as vapor deposition, it may be subject to oxidation etc. depending on the vapor deposition conditions. The film quality may become unstable, the mechanical strength may deteriorate, and as the number of molded resin substrates increases, the surface condition changes, resulting in an increase in error flags and other problems such as deterioration of disk characteristics. was.

In view of the above-mentioned problems, the present invention provides a method for manufacturing an optical disk master that can improve the reliability of the optical disk master and extend its life.

Means to Solve the Problems In order to solve the above problems, the method for manufacturing an optical disk master of the present invention involves coating a glass substrate with 7-photoresist, recording a signal with a laser beam, and developing it to form a glass master. After that, a metal thin film of a different type from the material used for plating is formed on the glass master by a method such as vapor deposition, and a plated film is formed by performing a plating process, and then the metal thin film is etched by a method such as etching. It consists only of removed and plated film.

According to the above-described structure, the present invention coats a glass substrate with a photoresist, records a signal with a laser beam, and develops it to form a glass master, and then forms a thin metal film of a different kind from the plating material by a method such as vapor deposition. If the metal thin film is removed after plating is performed to form a plating film, an optical disk master consisting only of the plating film can be obtained. Since there is no metal thin film, a plated film of excellent quality forms the surface, making it possible to obtain a highly reliable master for optical discs with a long life.

Embodiment A method for manufacturing an optical disk master according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1a to 1g are cross-sectional views showing the manufacturing process of an optical disk master according to the present invention. FIG. 1a shows a glass substrate 7,
FIG. 1 shows a process of coating a photoresist 8 on a glass substrate 7 and then recording a laser beam 9 corresponding to a digital signal. FIG. 1g shows a developing process, in which a glass master disk is formed on which a digital signal section 1o formed by the laser beam 9 is provided. Figure 1d shows aluminum (a material different from nickel (Ni), which is the plating material used in the next plating process) on the glass master disk.
A4) shows the step of providing the metal thin film 13 by a method such as vapor deposition. FIG. 1e shows a step of forming a nickel (Ni) plating film 13 on the metal thin film 13 by electroplating. FIG. 1f shows a composite substrate provided with an aluminum q metal thin film 13 and a nickel plating film 12. Figure 1g
In this example, the Al metal thin film 13 is removed by a chemical etching method in which the composite base material is immersed in a weakly alkaline sodium hydroxide (NaOH) aqueous solution, and an optical disk master is formed of only the Ni plating film 12. shows.

Generally, nickel (N1) is used as a plating material for glass masters in electroplating because it has high hardness and is easy to perform plating. In addition to aluminum (mul), materials different from nickel (Ni), which is the plating material mentioned above, include silver (Ag), copper (Cu),
The material may be a material such as titanium (Ti), which is a different material from N1, and which can be chemically etched selectively in a specific aqueous solution such as acid or alkali.

In addition to chemical etching, it is also effective to remove only the metal thin film different from the plating material by physical etching methods such as sputtering and ion etching.

In this way, if a thin metal film different from the plating material is formed by a method such as vapor deposition and then removed by a method such as physical or chemical etching, only a metallurgically stable plating material can be used. Since a master disc for an optical disc is formed, it has the advantage of being highly reliable and stable as an optical disc master disc.

Effects of the Invention As described above, according to the present invention, a photoresist is coated on a glass substrate and 1. After recording a signal with a laser beam and developing it to form a glass master disk, a metal thin film of a different type from the plating material is formed on the glass master disk, a plating process is performed to form a plating film, and then the metal thin film is formed. If a master disc for an optical disk is formed by removing it by a method such as etching, there is no metal thin film formed by a method such as vapor deposition, which has many causes of relative instability, and only a stable and reliable plating film is formed. By obtaining a master disc for an optical disc, it is possible to provide a master disc for an optical disc that has improved reliability, a longer service life, and is excellent in mass production.

[Brief explanation of drawings]

FIGS. 1(a) to (g) are cross-sectional views showing the steps of a method for manufacturing an optical disk master in an embodiment of the present invention, and FIG.
2L) to (f) are cross-sectional views showing the steps of the conventional optical disk master manufacturing method;
) are a plan view, a sectional view, and an enlarged view of essential parts of a digital audio disc, which is a type of optical disc. 1...Disk, 2...Resin substrate, 7
...Glass substrate, 8 ... Photoresist, 9 ... Laser light, 10 ... Digital signal section, 12 ... Plating film, 13...
...Metal thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A glass master is formed by applying a photoresist to a glass substrate, recording a signal with a laser beam, and developing it. After that, a thin metal film of a different type from the material used for plating is formed on the glass master by a method such as vapor deposition. A method for manufacturing an optical disk master consisting only of a plating film, by forming a plating film by performing a plating process, and then removing the metal thin film by a method such as etching.