JPS62130290A - Production of aluminum matrix for optical disk - Google Patents

Abstract

PURPOSE:To obtain a matrix for optical disks in simple producing stages by using Al as the material of a matrix and providing fine unevenness for reproducing signal information or a tracking guide to the surface of the material. CONSTITUTION:The surface of Al as a base material is mirror-polished and a resist applying stage, an etching pattern forming stage and a dry etching stage are successively carried out. Thus, fine unevenness for reproducing signal information or a tracking guide is provided to the surface of the base material and an Al matrix for optical disks is obtd. By this method, conventional Ni electroforming is made unnecessary and matrix producing stages can be simplified.

Description

[Detailed Description of the Invention] Industrial Field of Use This invention is used as a recording medium for video information, data information, etc., and is used for manufacturing optical discs on which information can be read or written by optical methods. The present invention relates to a method of manufacturing an optical disk master, and particularly to a method of manufacturing an aluminum master using aluminum as the master material.

In this specification, the term aluminum is used to include aluminum alloys.

Conventional technology and its problems Optical disks include those in which fine irregularities for signal information are formed on the surface of a substrate, and these irregularities are read by an optical method to reproduce signals, and those called magneto-optical discs, for example. First, fine irregularities for tracking guides are formed in a spiral shape on the surface of the substrate, and a recording medium thin film such as a magnetic film is attached to the surface of the irregularities, and the change in the characteristics of this recording medium thin film with respect to light is used to record information. There are known devices that can read or even rewrite.

In general, the production of such optical discs involves the use of a mask, in which microscopic asperities for IU products, whose concavities and convexities are reversed, are nailed onto the surface of the substrate in order to form fine concavities and convexities for signal information or tracking guides on the substrate. Alternatively, it is carried out by using a master disc for an optical disc called a standber, using this master disc as a mold, and molding a synthetic resin, which is a substrate material, into a disc by a method such as injection or casting.

In the conventional master disc as described above, fine irregularities are formed on a glass disc whose surface has been polished, and the same fine irregularities as the fine irregularities for signal transmission or tracking guide to be formed on the substrate are formed, and then the surface of the glass disc is polished. Since it was manufactured by making it a conductor, applying nickel electroforming, and then peeling off the electroformed layer, the manufacturing process was complicated and the cost was high.

The present invention has been made in order to eliminate such drawbacks, and aims to provide a master disc for an optical disc that has a simple manufacturing process and is inexpensive.

Means for Solving the Problems For this purpose, the present invention uses aluminum as the material of the master disk, and attempts to form fine irregularities on the aluminum material for duplicating signal information or tracking guides.

That is, the present invention mirror-finishes the surface of the aluminum base material, and then sequentially performs the steps of coating (+i), forming an etching pattern, trie, and tinting, so that the surface of the aluminum base material is coated with a mirror finish. The gist of the present invention is a method of manufacturing an aluminum master disc for an optical disc, which is characterized by forming minute irregularities for signal information or tracking guide 1 production.

The material of the aluminum base material is not particularly limited, and may include high-purity aluminum, kQ-Mg alloy that has been used as a magnetic disk, AQ-5i alloy that has a proven track record as a wiring material for semiconductors, and heat-resistant AQ-Ni series alloy, AQ-Zr series alloy or AQ-C alloy for
U-based alloys etc. can be used. In this case, it is desirable that the amount of the alloying element added be within the solid solution range, and in order to eliminate or reduce the size of the second phase particles, high purity aluminum (9
9.9 wt% or more) is preferable.

The mirror finishing applied to the surface of the aluminum base material gives the bottom surface of the concave part and the top surface of the convex part of the fine irregularities for duplication, which are formed on the surface of the base material through the subsequent dry etching process, to the smoothness required for a disc master. It is something that is done in order to make it something that we have.

The mirror finishing method may be by cutting or polishing, and it is preferable to polish after cutting.

After mirror finishing, fine irregularities for signal information or tracking guide 1u are formed on the processed surface. By the way, extremely strict accuracy is required for the fine irregularities formed on the disk substrate (No. 5 information or tracking guide).

For example, when forming unevenness for a tracking guide on a disk substrate, the dimensions of the guide groove are approximately 0.8 to 1 μm in width;
The depth is required to be approximately 0.07 μm, and the corner radius of the groove is required to be small. Therefore, the above-mentioned precision is naturally required for the fine irregularities for reproduction to be formed on the master. In order to realize such fine processing, the present invention employs a method in which the steps of applying photoresist to the sample surface, forming an etching pattern, and dry etching are sequentially performed.

The photoresist is applied during dry etching to prevent corrosion of the aluminum group +4 surface, except for the exposed portions during the etching pattern formation process.

The photoresist may be of either positive or negative type, but positive type is preferable.

As an example of such a photoresist, there may be mentioned a commercially available semiconductor first mask resist ink and the like. Further, as a coating method, any known method such as the date pink method or the roller flow water method may be employed.

In addition, the etching pattern forming step exposes the surface of the base material in accordance with the portions where four parts are to be formed for summer production.

As one of the specific steps for forming the etching pattern, we will first cite a case in which the steps of mounting a photomask, exposing to light, and developing are carried out in sequence. In other words, for example, a photomask is attached to the surface of the sample in which the area where the four parts for production are scheduled to be formed is the light-transmitting part and the area where the convex part for duplication is to be formed is the light-shielding part, and then this is exposed to light. Unnecessary resist in the area irradiated with light through the light-transmitting part is removed by a development process, and a predetermined etching pattern is formed on the surface of the base material. In addition, without using a photomask,
The resist may be exposed by directly irradiating the resist with a laser.

Further, as another method of forming an etching pattern, a method of partially removing the resist corresponding to the etching pattern using a processing laser is also recommended from the viewpoint of workability.

The dry etching is performed to erode the exposed surface of the aluminum base material according to the etching pattern. The type of dry etching is not particularly limited, and various methods including ion beam etching, reactive ion etching, etc. can be employed.

By this dry etching, the surface of the aluminum base material is processed into fine irregularities.

After dry etching, the resist adhering to the surface of the aluminum group is removed using an alkaline solution of 7 tons, if necessary.

By the way, after dry etching, the preservation by anodizing treatment 1
Forming wave crests on the surface of the master using a □ψ film or a resin film that can be removed during use is also effective from the standpoint of preventing scratches.

In order to manufacture an optical disc using a master disc manufactured by the method described in 1., first, the master disc is used as a mold and a synthetic resin is molded into a disc substrate by a method such as injection or casting. The fine irregularities for signal information or tracking guide are reproduced on the substrate by the fine irregularities formed on the surface of the master.

Thereafter, depending on the type of disc, a recording medium thin film is deposited on the substrate surface, or a transparent protective film is formed, thereby completing the optical disc.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, aluminum is used as the material for the optical disk master, and fine irregularities for recording information or tracking guide duplication are formed on this aluminum material, so that it is different from the conventional master. There is no need to perform nickel electroforming as described above, which simplifies the manufacturing process of the master disc, and makes it possible to provide a master disc at a low cost.

Furthermore, in this invention, the formation of fine irregularities for reproduction on an aluminum base material is carried out by mirror-finishing, applying photoresist, forming an etching pattern, and performing dry etching in sequence. , it is possible to perform microfabrication with extremely high precision, and to achieve sufficient smoothness of the bottom surfaces of the four parts and the top surfaces of the convex parts, and it is possible to provide a master disc for an optical disc that is excellent in terms of quality.

Example Next, examples of this invention will be shown.

Thickness 2. Ornm's AQ-1,0 wt% Si alloy (Af
130 nm in outer diameter.
rm, a donut shape with an inner diameter of 15 mm was punched out to form a base) 71, and the surface of the base material was mirror-finished by cutting. After that, an acrylic resin (PMMA) as a resist is applied to the mirror-finished surface of the base material, and then the area where the duplication convex part to form the tracking guide on the disk substrate is planned to be formed is a light shielding part, and the other parts are A photomask having a light-transmitting portion was attached, exposure was performed through the mask, and development was performed to form a predetermined etching pattern on the surface of the aluminum base material.

Afterwards, BCQ3 and C
By performing dry etching by reactive ion etching using a mixed gas with CQ4, the exposed aluminum portion was eroded and fine irregularities for tracking guide duplication were formed on the surface of the aluminum base material, which was used as a master disc.

Due to the above? When the dimensions of the recesses were measured on the master disc that had been removed from the market, the width was found to be 0. It has a viscosity of 8"006μm1 depth 0.07-o, oor μm, the corner radius of the four parts is 0.01μm, and the surface roughness of the bottom is R[1lax0. It was 01 μm.

From the above two results, it was confirmed that the present invention has the ability to produce an aluminum master disc that satisfies the precision required for the first disc.

that's all

Claims (1)

[Claims] After mirror-finishing the surface of the aluminum base material, the steps of applying a resist, forming an etching pattern, and dry etching are sequentially performed to create fine patterns for signal information or tracking guide reproduction on the surface of the aluminum base material. A method for producing an aluminum master disk for optical discs, which is characterized by forming unevenness.