JPS631679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive recording medium in which a photoresist (photosensitive composition) is applied to a substrate and microfabrication is performed, and particularly relates to a photosensitive recording medium that is difficult to peel off.

Conventionally, the structure of a photosensitive recording medium has generally had the structure shown in FIG. In the figure, 1 is a substrate and 2 is a photoresist film. In other words, it has a structure in which photoresist is directly applied after cleaning the surface of the substrate.

When performing microfabrication on such a structure, it is necessary to maintain sufficient adhesion between the substrate and the photoresist. However, conventional photosensitive recording media have the disadvantage that the photoresist often peels off after development or water washing due to insufficient adhesion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive recording medium for an optical disk that can prevent peeling between a substrate and a photoresist and can form recording grooves with high precision.

In order to achieve the above object, the present invention provides a transparent substrate, a metal thin film with a reflectance of 8% or less made of a single metal material directly stacked on the transparent substrate, and a metal thin film on the metal thin film. This structure is characterized by consisting of directly loaded photoresist.

The invention will now be described in detail with reference to the accompanying drawings. FIG. 2 shows a cross-sectional view of a recording medium that is an embodiment of the present invention. In the figure, 1 is a substrate, 2 is a photoresist, 11 is aluminum, gold, silver,
It is a thin metal film made of copper, chromium, etc. When the substrate 1 is made of glass, the adhesive force between the glass substrate and the metal thin film 11 is greater than when photoresist is applied directly onto the glass substrate. Furthermore, the adhesive force between the metal thin film 11 and the photoresist film is strong. This means that even if the photoresist is subjected to high-density microfabrication, the photoresist film will not peel off during development and water washing. For example, when creating a video disk master plate, a chromium film with a reflectance of 8% or less, for example 30 Å, is placed on a 15 mm thick glass substrate.
A thin film is formed by vacuum evaporation technique, and a photoresist film with a thickness of 0.2 μm is formed thereon. As a photoresist, for example, positive photoresist AZ1350 containing quinone diazide and novolak resin is used.
(Shipley) was used. As the developer, AZ developer was used. Then, a laser beam with a spot size of about 1 μm is irradiated to record a high-density video signal. In such a case, no peeling of the photoresist film occurred after development and water washing. The same applies to other metal thin films such as aluminum, gold, silver, and copper. Among these metal thin films, the chromium film has the strongest adhesion to glass and is therefore most effective.

Furthermore, since peeling of the photoresist film can be prevented, it is useful for reducing dropouts.

However, when the reflectance is 8% or more, the reflected light from the metal thin film to the photoresist film becomes strong, which adversely affects the recording groove, especially the groove width. When the exposure and development conditions of conventional recording media are used for the recording medium of the present invention, the groove width may be processed to be larger than the intended dimension depending on the reflectance of the metal thin film 11. FIG. 3 shows the relationship between reflectance and groove width when Cr is used as the metal thin film in the above implementation.
However, when the metal thin film is as thin as an elbow, the reflectance is considered to be only the glass substrate, so the reflectance starts from 4% (the reflectance of the glass substrate). From Figure 3, when the reflectance is 8% or less, the groove width can be processed to the desired size, but when the reflectance is 8% or more, the groove width is larger than the desired size (for example, 0.8μ), and the reflectance increases. It gets bigger as it increases. In particular, when the reflectance is 31%, the groove width is twice as large as when the reflectance is 8% or less.

That is, the reflectance of the metal thin film 11 needs to be 8% or less.

As described above, the present invention is applicable to photoresist processing that uses laser light to perform high-density recording in the production of optical discs such as video discs.
This has the effect of preventing peeling and enabling photoresist processing with high dimensional accuracy of the recording groove width. Furthermore, the present invention has the effect that the amount of light when a photosensitive recording medium for an optical disk is irradiated with laser light can be determined by detecting the light transmitted through the transparent substrate, so that the amount of light can be detected with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional example, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between reflectance and groove width. 1 is a substrate, 2 is a photoresist, and 11 is a metal thin film.

Claims (1)

[Claims] 1. A transparent substrate, a metal thin film with a reflectance of 8% or less made of a single metal material, and a photoresist placed directly on the metal thin film. A photosensitive recording medium for optical discs.