JPS6118815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording board and a method for manufacturing the same.
In particular, the present invention relates to a recording plate whose surface is irradiated with a scanning beam such as a laser beam or an electron beam to record information, and a method of manufacturing the same.

2. Description of the Related Art As a method for recording video and audio information on a disk-shaped recording medium, there is a method for optically recording video disks, for example. This method involves applying a photoresist with a thickness of 1000 to 1500 Å to a glass disk serving as a substrate, and irradiating this resist film with a laser beam focused on a minute point using the so-called bit-by-bit method, which blinks in response to video and audio information. Information is recorded based on the length of the pits (dents) obtained by exposure to light and subsequent development, and the repetition period thereof.

In this method, the steps of the photoresist film are transferred to a plastic plate or the like and read out, so uniformity is required over the entire surface when the resist film is applied to the substrate. Loss of such uniformity is undesirable as it is a major cause of deterioration of the S/N of the reproduced signal, but it is difficult to apply such a resist film to a uniform thickness over the entire surface of the disk (approximately 300 mm diameter). be.

Therefore, the following methods have been proposed to eliminate such drawbacks. That is, a silicon oxide film that can be selectively etched is formed on one principal surface of the substrate to a uniform thickness by a method such as vapor phase growth, and then a chromium film that can be melted and evaporated with a laser beam is formed on the oxide film. do. By scanning the surface of the disk substrate thus obtained with a laser beam modulated according to predetermined information, the chrome film is melted and evaporated according to the information. By selectively etching the underlying silicon oxide film using this chrome film as an etching mask, and then removing the chrome film, pits corresponding to the information are formed in the silicon oxide film.

In this method, the silicon oxide film is uniformly deposited on the substrate surface, so the above-mentioned drawbacks are eliminated. However, in this method and in the above-mentioned method as well, the size of the pit is larger than the normal size that should be produced according to the recorded information, and there is a drawback that accurate information cannot be recorded.

Furthermore, the substrate thus obtained, that is, the recording plate, is reproduced by transferring the steps of the pits onto a plastic plate, etc., but the inner surface of the silicon oxide film pits is substantially perpendicular to the substrate surface. Because of this, there is also the drawback that the plastic plate does not release easily from the mold after being transferred to the plastic plate.

An object of the present invention is to provide an information recording plate that allows accurate information recording and has good separation from the mold during transfer, and a method for manufacturing the same.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the present invention in the order of the manufacturing process.
For example, a silicon oxide film 2 with a thickness of 2000 Å is formed by a vapor phase growth method, and then a chromium film 3, for example, is formed on it.
form. A laser beam modulated according to predetermined information to be recorded is irradiated onto the substrate surface including the chrome film 3 to melt and evaporate the chrome film 3.
The structure shown in is obtained. After that, chrome film 3
If the silicon oxide film 2 is selectively removed by so-called plasma etching in plasma such as CF ₄ using the mask as a mask, and the chrome film 3 is completely removed, pits 4 according to the information are formed as shown in c. formed on a substrate.

However, since the shape of this pit 4 is normally formed larger than a regular pit, as shown in FIG. Let it form. In this case, since the thickness of the phosphor glass layer 5 must be approximately the same over the inner wall of the pit 4, its bottom surface, and the upper surface of the silicon oxide film 2, it is difficult to use the vapor phase growth method under normal pressure. However, the above object can be achieved by using the vapor phase growth method under reduced pressure. The atmospheric pressure in this case is preferably 10 Torr or less, for example.

Here, since the grown film 5 is for correcting the size of the pit 4 of c to an accurate size, its thickness must be strictly controlled. According to this, this is possible. Note that the vapor phase growth film 5 is not limited to phosphorus glass, and any material that can be vapor phase grown can be used. For example, a resin film or a metal film can be used.

Further, since the film 5 is for correcting the size of the pit, it is sufficient to form a film with a uniform thickness on at least the inner surface of the pit 4 shown in c. It is obvious that forming a vapor phase growth film over the entire main surface is easy in terms of manufacturing.

Furthermore, in the present invention, in order to improve the release of the transfer plate from the mold, for example, if the liquid phase polyimide 6 is formed on the entire surface by spin coating, as shown in e, the liquid phase will remain in the pit 4. polyimide 6
has a plastic viscosity and a given surface tension, so
The film is cured in such a manner that the film thickness becomes thinner at the upper corner of the pit 4, reaches its maximum thickness at the flat bottom part of the pit 4, and increases continuously from the upper edge to the lower edge of the inner wall. I will do it. Therefore, the inner circumferential wall of the pit is tapered, making it easier to separate from the mold during so-called transfer.

In addition to polyimide, polyimide amide, cyclic rubber resin, Teflon (DuPont), etc. can be used as a forming agent, that is, a curing agent for the liquid phase film 5.

Therefore, since the substrate obtained in this way allows a film with a uniform and precisely controlled thickness to grow on the recording surface, a film with a uniform thickness can also be grown on the inner wall of the pit. As it grows, it becomes possible to correct the size of the pit. In addition, since the liquid phase film is applied onto the grown film and cured, the peripheral edge of the pit shape has a tapered shape.
The mold can be easily removed during transfer. The same applies to the case where a plastic plate is obtained after producing an electroformed plate from the substrate.

[Brief explanation of the drawing]

FIGS. 1A to 1D are cross-sectional views in the order of manufacturing steps of an embodiment of the present invention. Explanation of symbols of main parts, 1...substrate, 2...silicon oxide film, 4...pits, 5...grown film, 6
...Liquid phase membrane.

Claims (1)

[Scope of Claims] 1. A substrate having a plurality of pits formed on one main surface according to predetermined information, and a substrate having a uniform thickness on at least the inner surface of each of the pits. and a second film deposited on the first film such that the thickness thereof continuously increases from the upper edge to the lower edge of the first film. Information recording board. 2. A step of forming pits on one main surface of the substrate according to predetermined information, a step of vapor-phase growing a predetermined film on the one main surface under reduced pressure, and a step of forming a pit in accordance with predetermined information with a predetermined surface tension. After applying a phase curing agent to the entire main surface of the predetermined film to form a liquid phase film whose thickness increases continuously from the upper edge to the lower edge on the predetermined film on the inner surface of the pit; A method for manufacturing an information recording plate, comprising the steps of: , curing.