JPS63138541A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To permit formation of a matrix by subjecting a photoresist layer on a base material to formation of the latent image of a diffraction grating by holographic exposing and to exposing through a mask having a fine pattern and developing said layer. CONSTITUTION:The photoresist layer 3 of a positive or negative type is formed on the substrate 2 consisting of glass, etc., and the latent image of the diffraction grating is formed on the layer 3 by subjecting said layer to the holographic exposing by laser light. The layer 3 is then exposed and developed through the mask 4 on which information is recorded to a fine various density pattern. A metallic layer 5 is then formed on the pattern to form the matrix. A stamper is generated from said matrix and the reproduction of a medium is executed by using the resultant stamper. The selective formation of the diffraction grating part and smooth part is permitted and the formation of the matrix is facilitated according to this method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method of manufacturing a read-only optical recording medium.

(Prior Art?#) Optical recording has advantages over magnetic recording in that the recording medium and the reproducing head are not in contact with each other, and high-density recording is possible. As this optical recording medium, there are known read-only ones, additionally writable ones, and erasable and rewritable ones.The read-only optical recording medium according to the present invention is firstly a compact compact that has already been put into practical use. Examples include discs (CDs) and optical video discs. The method used in these optical recording media is that information is recorded on a concave-convex structure formed in the medium, and in order to increase the recording density of information, the recording bit (the smallest unit of concavity or convexity) is approximately 1 μm in size. The information is read by focusing the reproduction light to the same size as the bit using a high-speed source such as a laser, but the fact that the readout light beam is minute is that Problems arise in that techniques for autofocus and autotracking, as well as expensive laser beams, must be used.

On the other hand, as an optical recording medium of another type, a part having a high optical reflectance and a part having a low reflectance are made of different materials, and a pattern is formed using this ML to record digital information. There are known recording media. A method for forming a light and shade pattern using this method is, for example, as disclosed in Japanese Patent Laid-Open No. 60-66346, in which an optical low reflection layer and an optical high reflection layer are laminated in this order on a substrate, and one surface is coated with a photoresist. The photoresist is coated, exposed to light through a mask with a fine shading pattern, and then the photoresist is developed to form a resist pattern.
Thereafter, etching is performed in a pattern using a resist pattern to remove the high optical reflection layer and expose the low optical reflection layer. Although this method does not require the use of expensive laser beams, it requires a large number of manufacturing steps as described above, and each step is not easy to perform.

Another method that does not require the use of a laser beam is an optical recording medium in which the recording pit, which is the smallest unit of information, is composed of a diffraction grating, but it is possible to select an optical recording medium in which the recording pit, which is the smallest unit of information, is composed of a diffraction grating. It is not easy to form a diffraction grating in one diffraction grating section.

(Object of the Invention) The present invention has been made in view of the problems of the prior art described above, and does not require the use of an expensive laser beam for reading. Moreover, it is an object of the present invention to provide a method for manufacturing a read-only optical recording medium that can be reproduced in large quantities using a simple method.

(Summary of the Invention) The present invention involves applying a photoresist onto a base material, holographically exposing the formed photoresist layer using a laser beam to form a latent image of a diffraction grating, and then forming a fine shading pattern. After that, the photoresist is developed to obtain a recording pattern. This is a method for manufacturing an optical recording medium, in which a stamper is raised from the obtained recording pattern, and an optical recording medium having a diffraction grating provided in a fine pattern is reproduced using the stamper.

(Detailed description of the invention) The present invention will be explained in detail below based on the drawings.

Figures 1 to 5 show the steps of manufacturing a recording pattern stamper mold in order, and Figure 1 shows the optical recording material 1.
11, in which a photoresist layer (3) is laminated on a base material (2). Both positive and negative type photoresists can be used, but those that are easy to apply and have high resolution that can sufficiently resolve fine information recording patterns during exposure are selected and used.

As such a photoresist, AZ-1350 made by Sibley Co., Ltd. is a positive type photoresist. 0FPR-2- manufactured by Tokyo Ohka Kogyo ■
800, 5000, TSMR-8800, negative type OMR-83, 85, 0NNR-20 manufactured by Tokyo Ohka Kogyo ■
, 22, CIP-200 and 300 manufactured by Toyo Soda Kogyo ■ can be used. Base material (2) has characteristics 1 suitable for the application
For example, a material that has a smooth surface, durability, etc., and is not affected by deterioration or deformation in post-processes, photoresist development, and stamper molding steps is selected and used.

Examples of such materials include glass, wood (acrylic).

epoxy, nylon, etc.), metals (steel, nickel, etc.).

AJ, etc.) can be used.

For such an optical recording material, the photoresist layer [3) is holographically exposed using a laser exposure device to form a latent image of one diffraction grating (FIG. 2). The laser light source used is an argon laser (458 nm
), helium-cadmium laser (442 nm), and the like. Here, the number of grooves of the diffraction grating per unit length can be arbitrarily controlled by determining the wavelength of the laser and the setting conditions of the laser exposure device. Furthermore, a diffraction grating in which the grooves are serrated (a blazed diffraction grating) can also be formed depending on the setting conditions of the laser exposure apparatus. Furthermore, since the diffraction grating is directly formed using laser light, a highly accurate diffraction grating can be obtained.

Next, the photoresist (i+31) was exposed to light through a mask (4) on which information was recorded in a fine density pattern (FIG. 3), and then the photoresist was developed.

A resist pattern in which a diffraction grating is formed is formed (FIG. 4). Thereafter, a metal layer (5) is formed on the surfaces of the photoresist layer (3) and the base material (2). Metal 1*
(51 is formed by selecting a metal that is not inconvenient when applying a technical method (for example, electroforming) to create a stamper in the form (matrix) shown in Figure 4 in the subsequent process, and performing vacuum evaporation or sputtering. If the metal layer (6) is made of a metal that has a higher optical reflectance, irradiating this state with read light makes it possible to reproduce and confirm the recording state.

A stamper is formed from a matrix obtained by a technique such as electroforming (Fig. 6), and the obtained stamper (6) is used to perform mass duplication of optical recording media.

Replication methods include injection molding, compression molding, and methods using ultraviolet curing resin, but a method that produces high-quality and efficient replicas should be selected before proceeding. A metal with high optical reflectance is selected for the surface of the replicated base material (7), and a metal layer (
8) is formed (FIG. 7), and a protective layer made of an optically transparent material (9) is formed thereon (FIG. 8). In this case, the reading light is irradiated from the side of the material (9), but conversely, the base material (7) is made of a material that also has optically transparent properties, and the reading light is irradiated from the side of the base material (7). method is also possible.

It is also possible to transfer optically recorded information by compression molding a thermoplastic resin having a metal thin film having high optical reflectance on its surface using a stamper (7). In the optical recording medium obtained in this way, when the shape of one diffraction grating is a sinusoidal waveform and its depth is 0.16 μm, He
- When irradiated with Ne laser (652,8 mm) at an incident angle of 0°, the diffraction efficiency is 3 B, and the 1 reflectance is 10 in the smooth part.
0 to 1 diffraction grating portion 54, and a contrast of about 60 is confirmed. The reading light is not limited to the above-mentioned laser light, but it is also possible to use a light emitting diode or the like, which enables reading without the need for a special light source.

(Examples) The present invention will be explained below with reference to Examples, but the present invention is not limited to the Examples. A photoresist (AZ-1550 manufactured by Shipley) was coated with a spinner on a glass plate with a smooth surface measuring 6 to 74 m long and 5 to 6 cr IL wide, and after drying (90'C) -Ar laser (458 mm)
) is used to perform holographic exposure to form a latent image of a diffraction grating, and then exposure is performed through a mask having a fine pattern.

Thereafter, the photoresist is developed to form a resist pattern. Thereafter, gold vapor deposition was performed on the obtained resist pattern to form a conductive thin film.

A nickel stamper was created using nickel electroforming using a sulfamic acid nickel bath, and the shape of the nickel stamper was transferred by compression molding onto a polyvinyl chloride sheet of 0.5 thickness, and the resulting transfer surface was coated with aluminum. After vapor deposition, when we observed with a microscope the area where the diffraction grating was provided and the area where it was not, that is, the smooth area, we could clearly distinguish between the two, and we also used the light emitting diode as reading light to read the data using a CCD line sensor. However, a practically sufficient S/N ratio was obtained.

(Effects of the present invention) According to the present invention, it is possible to selectively form the diffraction grating portion and the smooth portion, and it is also possible to form various highly accurate diffraction gratings by recombining the laser optical device. It should also be possible to perform mass duplication of media.

[Brief explanation of the drawing]

FIGS. 1 to 5 are explanatory diagrams showing each process of manufacturing a matrix, and FIGS. 6 to 8 are explanatory diagrams showing each process of mass replication. (1)...Optical recording material (2)...Substrate (3)...Photoresist (4)...Mask

Claims (1)

[Claims] A method for manufacturing an optical recording medium in which a concavo-convex pattern is formed of a material having high optical reflectance and a diffraction grating is formed on at least one of the concave portions or convex portions of the concave-convex pattern, the method includes: A resist is applied, the formed photoresist layer is holographically exposed using a laser beam to form a latent image of a diffraction grating, and then a mask having a fine shading pattern corresponding to the signal to be recorded is used. It is characterized by exposing to light, then developing the photoresist to obtain a recording pattern, creating a stamper from the obtained recording pattern, and using this stamper to reproduce an optical recording medium in which a diffraction grating is provided in a fine pattern. Method for manufacturing an optical recording medium