JPH05144094A - Production of optical disk stamper - Google Patents

Abstract

PURPOSE:To simplify stages by executing the rear surface polishing of a stamper after an electrocasting stage. CONSTITUTION:The parts of retainers 8 of a molding flask may be molded of the same material as the material of a side wall 7 or of a material different therefrom. The shape of the retainers 8 is not particularly specified, insofar as a glass master disk can be fixed. If the material of the retainer parts 8 is different from the material of the side wall 7, the material which tightly adheres to the side wall 7 and withstands an electrocasting temp. is more preferable. The stamper, master disk and retaining die are washed and dried together upon ending the electrocasting. The stamper can be polished while the rear surface thereof is held tightly adhered to the master disk by using the molding flask and, therefore, there is no need for protecting the signal surface of the stamper and the stages are simplified. The molding flask and the stamper are removed from the glass master disk and the inside and outside diameters of the stamper are worked after the polishing, by which the stamper is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk stamper.

[0002]

2. Description of the Related Art Conventionally, a stamper for an optical disc is usually manufactured by the following method. That is, after precisely polishing a master made of glass or the like, precision cleaning and surface treatment are performed, a positive photoresist layer is formed on the glass master, and laser light is irradiated from the inner circumference to the outer circumference at a constant speed. A predetermined information recording pattern is exposed and this resist layer is developed to form a fine information recording pattern.

A conductive metal (eg, nickel) conductive film (electrode) is formed on the substrate master having this information recording pattern by a method such as sputtering, and then electroforming,
In this method, a nickel stamper to which an information recording pattern has been transferred is manufactured by polishing, and then the back surface of the obtained stamper is bonded to a polishing jig to obtain a polishing stamper.

[0004]

According to the above-mentioned method, when the adhesion between the glass master and the resist layer is insufficient, in the electroforming step to be carried out next, for example, when nickel electroforming is performed, a positive electrode is often used. The mold photoresist layer may peel off from the glass master. As a result, various problems occur such as the accuracy of the electroformed thickness is deteriorated because the electroforming liquid enters the gap and floats between the electroformed layer and the glass master during electroforming.

Further, when the glass master and the resist layer, and hence the stamper and the glass master are peeled off, when the back surface of the stamper is polished later, for example, the signal surface of the stamper is protected by a protective film, and this surface is coated with double-sided tape or the like. Although it is adhered to a polishing jig with and is used for polishing, bubbles easily enter between the stamper and the tape at this time, and if polishing is performed with bubbles, it is difficult to polish the polishing surface with a uniform force. Therefore, there are problems such as uneven polishing. Further, the disk substrate manufactured using the stamper thus obtained has a rough surface, which causes an increase in the noise level of the substrate.

The present invention has been made in view of the above-mentioned circumstances of the prior art, and an object of the present invention is to provide a method for manufacturing a high-quality stamper by a simple process.

[0007]

As a result of various studies on the electroforming process for manufacturing a stamper, the present inventors have found that the conductive film and the peripheral portion of the glass master are physically fixed by a mold to perform electroforming. The present invention has been completed based on the finding that the above-described delamination phenomenon between layers does not occur and a high-quality stamper can be manufactured.

That is, the present invention relates to a method for manufacturing an optical disk stamper by electroforming a base material master having a conductive film formed thereon, and relates to a method for manufacturing an optical disk stamper in which the base material master is fixed by a mold and electroformed. is there.

The present invention will be described in more detail below. Figure 1 shows a resist master that has been cut (1 in the figure)
FIG. 3 is a cross-sectional view of a base material master on which a metal film such as Ni (3 in the figure) is formed. FIG. 2 is a diagram showing a method of mounting this master on a mold (4 in the figure), and FIG. 3 is a diagram in which these are fixed. The master thus fixed is subjected to electroforming treatment in the plating process.

The mold used in the present invention is for fixing the peripheral portion of the base material master. For example, the mold as shown in FIGS. 4 to 6, that is, the donut-shaped bottom plate (6 in the figure) has a side wall. In a formwork having (7 in the figure) and a presser (8 in the figure), the outer diameter of the bottom plate is larger than the diameter of the master, and the inner diameter is smaller than the diameter of the master and smaller than the diameter of the stamper to be manufactured. It's a big one. There is no problem in manufacturing the stamper as long as the outside diameter and the inside diameter of the bottom plate satisfy the above-mentioned range, but when considering an electroforming apparatus, the outside diameter is 105 mm of the diameter of the master. ˜115%, and the inner diameter is preferably 80 to 95% of the diameter of the master. However, the inner diameter is 80% depending on the master used and the outer diameter of the stamper to be manufactured.
It is also possible to:

It is sufficient that the inner diameter of the mold side wall is larger than the diameter of the master. If this inner diameter is too large,
Since the master is not firmly fixed in the form, it is preferable to handle it slightly larger than the master.

The thickness of the mold used in the present invention (thickness of the side wall portion) is not particularly limited, but it is preferable that it is substantially equal to or smaller than the thickness of the master in consideration of the work of putting the master into and out of the mold. . However, if the thickness is unnecessarily thin, the strength in handling when fixing the master is lowered, and it is not preferable for obtaining the target thickness of the stamper. Normally, it is necessary to have a thickness of about 200 μm or more, but considering the strength of the mold and the thickness of the stamper, 250-350 μm
m is preferred.

The material of the mold of the present invention is preferably a conductive substance in consideration of the electroforming process. Further, as a physically and chemically stable substance in the electroforming step, metal is preferable,
Among metals, the use of Ni, Fe or the like causes less contamination of the plating solution and gives good results. As for the material of the side wall of the mold, the same material as the bottom plate of the mold may be integrally molded.If different materials are used, the bottom plate of the mold should be sufficiently adhered and electroformed. Any material may be used as long as it can withstand a rise in temperature in the process, but when a metal is used for the bottom plate portion, metal is preferable from the viewpoint of adhesion. Further, it is preferable that the side wall portion has a shape that covers the entire peripheral side surface of the master in order to prevent the electroforming liquid from entering between the respective layers of the master, but a shape that fixes a part of the side surface is also possible. good.

The portion of the mold retainer (8) shown in FIG. 6 can be made of the same material as the side wall or a different material. The shape of the pressing portion is not specified as long as the glass master can be fixed. When the material of the pressing portion is different from that of the side wall portion, it is preferable that the material is sufficiently adhered to the side wall of the mold and can withstand the electroforming temperature. Further, the number of pressings is not particularly limited as long as the master can be firmly fixed.

Using the mold as described above, a stamper (5 in FIG. 7) is formed by electroforming a metal such as Ni on the resist pattern in an electroforming tank. After electroforming, the stamper, master and pressing die are washed together and dried. Also, one of the advantages of the method of the present invention, using this form,
The point is that the back surface of the stamper can be polished while it is in close contact with the master. Therefore, the step of protecting the signal surface of the stamper can be omitted. After polishing, the mold and stamper are removed from the glass master and the inner and outer diameters of the stamper are processed to manufacture the stamper.

[0016]

As described above, according to the present invention, the resist does not peel off from the master in the electroforming process, the subsequent process can be simplified, and a high-quality stamper can be manufactured. Specifically, since the back surface polishing work of the stamper is performed after the electroforming step, conventionally, it is necessary to coat the signal surface of the stamper with a protective film and adhere the stamper to a polishing jig with tape or the like for polishing. However, this step can be omitted by the present invention. Furthermore, uneven polishing due to warpage of the stamper is eliminated.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 First, a positive type resist 2 was formed on one surface of a glass master having an outer diameter of 200 mm and a thickness of 6 mm, whose surface was precisely polished.
Was applied. After a Ni sputtered film was adhered to the cut resist master, electroforming was performed using the frame shown in FIG.

The Ni formwork has a side wall diameter of 203 φm.
m, height 3 mmt, bottom plate outer diameter 210 φ mm, inner diameter 185 φ mm, and Ni plate thickness 300 μm. In addition, there are four pressing parts, and the width is 10 mm and the length is 30 m.
It was a plate-shaped m and was made of Ni like the bottom part of the mold. A master having the surface with the resist film facing down was placed in the mold, and then the pressing portion of the mold was bent and pressed so that the resist and the master were not separated (see FIG. 3).

This product was electroformed with Ni on the resist pattern so that the stamper had a thickness of 295 to 300 μm (see FIG. 7). After electroforming, this master,
The stamper and the mold were washed together, and in the next polishing step, the mold was attached to the polishing jig while the mold and the master were still attached, and the back surface of the stamper was polished to a mirror surface.

After the polishing, the stamper and the mold were removed from the master, the inner and outer diameters of the stamper were punched out, and a washing process was performed to obtain a stamper. By using the pressing mold in the electroforming process, the manufacturing time of the stamper can be shortened, and there is no unevenness of polishing due to warp of the stamper, and a stamper having a uniform polished surface is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a base material master in which a metal film is formed on a resist master after cutting.

FIG. 2 is a diagram showing an example of a method of mounting a master on a mold.

FIG. 3 is a diagram showing an embodiment in which a master and a mold are fixed.

FIG. 4 is a view showing a cross section of an example of a mold used in the present invention.

FIG. 5 is a diagram showing a top surface of an example of a mold used in the present invention.

FIG. 6 is a diagram showing an overview of an example of a mold used in the present invention.

FIG. 7 is a cross-sectional view of a stamper and a base material master of the stamper obtained by electroforming using a mold.

[Explanation of symbols]

 1: Glass master 2: Resist film 3: Ni sputtered film 4: Formwork 5: Stamper 6: Formwork bottom plate 7: Formwork side wall 8: Formwork hold down

Claims (1)

[Claims] 1. A method for manufacturing an optical disk stamper by electroforming a base material master having a conductive film formed thereon, wherein the base material master is fixed with a mold to perform electroforming.