JPH0630170B2 - Optical disc master and method of manufacturing the same - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for producing a disc capable of recording, reproducing or erasing digital signals such as digital audio discs (eg compact discs), video discs, still images, document files, etc. And a method for manufacturing the same.

Structure of conventional example and its problems This kind of optical disk is promising as an information medium due to its extremely high information density, large S / N, and low noise, and it is commercialized as a digital audio disk or video disk. Recently, it has been researched and developed as a disc capable of recording, reproducing and erasing digital signals.

FIG. 1 shows an outline of a compact disc which is a general digital audio disc.

In this method, a PCM-converted digital signal is recorded on a resin substrate in the form of pits and reproduced by a semiconductor laser. In FIG. 1, 1 is the whole disc, 2 is a resin substrate, 3 is a digital signal provided on the resin substrate, 4
Is a reflective film formed on the surface thereof, 5 is a protective film coated on the reflective film, and 6 is a semiconductor laser for reproduction irradiated from the disc reading surface.

The resin substrate 2 is generally mass-produced by a molding method such as injection molding or injection / compression molding. The optical disc master is attached to a molding die required for forming the disc.

FIG. 2 shows a conventional optical disk master and its manufacturing method. 2A to 2F are cross-sectional views in each step.

Photoresist 8 is applied to glass master 7, laser-exposed and then developed to record digital signal 9.
Next, a metal thin film 10 of Ni or the like is provided, and a Ni plating layer 11 is provided. After that, the optical disk master 12 is obtained by removing the glass master.

The master for optical disk thus obtained is attached to a molding die, and a resin such as polycarbonate is injection-molded to obtain a resin substrate. In this case, since the surface roughness of the master is generally low, the friction resistance between the master and the resin is large, the flow of the resin on the master surface is deteriorated, and it is difficult to reduce the birefringence of the entire disc. However, there is a problem that the optical characteristics are deteriorated such as a poor appearance due to the turbulent flow of the resin.

SUMMARY OF THE INVENTION The present invention solves these problems and provides an optical disk master for forming an optical disk having excellent optical characteristics and a method for manufacturing the same.

The present invention relates to an optical disk master having a surface roughness of 10Å to 100Å, which is obtained by applying a photoresist to a glass master, recording and developing it, and then physically or chemically treating the master to manufacture the same. Is the way.

Description of Embodiments FIG. 3 shows an embodiment of an optical disk master and a manufacturing method thereof according to the present invention. 3A to 3G are cross-sectional views in each step.

The glass master 7 is coated with a photoresist 8, laser-exposed and developed to form a digital signal 9.
Then, the surface of the photoresist is roughened by ion bombardment as shown in FIG. 3d, and the surface roughness is 10Å-1.
A photoresist film 13 having a rough surface to be 00Å is formed. Next, a metal thin film 14 of Ni or the like is provided, and a Ni plating layer 15 is provided. Then, the glass master disk is removed to obtain the optical disk master disk 16. In this case, since the photoresist surface state is transferred as it is, the surface roughness of the master surface becomes 10Å to 100Å.

When the optical disk master thus obtained is mounted on a molding die and injection molded with a resin such as polycarbonate, the surface roughness of the master disk is as large as 10Å to 100Å, so the friction resistance between the master surface and the resin is large. Is smaller, the fluidity of the resin is improved, the birefringence is improved, and the appearance defects due to the turbulent flow of the resin are less likely to occur.

An experiment was conducted on the surface roughness of the optical disk master, but this is N
Although it is also related to the grain size of the metal thin film such as i, observation with an electron microscope revealed that 10Å to 100Å is optimal.

As a treatment method for roughening the photoresist surface, physical methods such as ozone cleaning, sputtering and reverse sputtering, or chemical methods such as etching, electrolytic cleaning and reverse electrolytic plating were effective.

EFFECTS OF THE INVENTION As described above, according to the present invention, after applying a photoresist to a glass master, recording and developing the photoresist, roughening the photoresist surface and providing a master for optical disks having a surface roughness of 10Å to 100Å, Frictional resistance between the master surface and molten resin is small, the fluidity of the resin is good, the birefringence is small, and there is no appearance failure due to turbulent flow of the resin. There is an effect that a large amount can be provided at low cost.

[Brief description of drawings]

1a, 1b, 1c, and 1c are a plan view, a sectional view, and an enlarged view of a main part of a digital audio disc, which is a type of optical disc, and FIGS. 2a to 2f are sectional views showing a conventional optical disc master and its manufacturing process. 3A to 3G are sectional views of manufacturing steps showing one embodiment of the present invention. 1 ... Disk, 2 ... Resin substrate, 3 ... Digital signal, 4 ... Reflective film, 5 ... Protective film, 6 ... Semiconductor laser, 7 ... Glass master, 8 ... Photoresist, 9 ...
Digital signal, 13 ... Photoresist, 14 ... Nickel thin film, 15 ... Nickel plated layer, 16 ... Optical disc master.

Claims (3)

[Claims] 1. An optical disk master, wherein the surface of the signal surface has a surface roughness of 10Å to 100Å. 2. A glass master disk is coated with a photoresist, recorded and developed to form a digital signal, and then the photoresist surface is subjected to a physical or chemical treatment to obtain a surface roughness of 10 Å to 100 Å. After that, a method of manufacturing an optical disk master, characterized by being subjected to Ni plating treatment. 3. As a treatment method for roughening the photoresist surface, a physical treatment method such as ozone cleaning, ion bombardment, sputtering, reverse sputtering or a chemical method such as etching, electrolytic cleaning, reverse electrolytic plating is used. The method of manufacturing an optical disk master according to claim 2.