JPH02196640A - Manufacture of stamper for optical disk - Google Patents

Abstract

PURPOSE:To manufacture a stamper for an optical disk of superior precision with high yield and without introducing particularly sophisticated process into the manufacturing method heretofore available by ozone treating a matrix surface before coating the surface of a glass matrix with coating fluid for forming photoresist layer. CONSTITUTION:An organic film 12 is formed on the surface after several tens of minutes after washing a glass matrix 11, and then ozone gas is jetted to the surface of glass matrix 11 to remove the organic film 12. Then, coating fluid for photoresist is applied on the surface of ozone treated glass matrix 11 as soon as possible after treatment. The bonding properties of the glass matrix and a photoresist layer is enhanced by the process, and stripping phenomenon such as lowering of thickness precision generated by an electroforming layer released from the glass matrix together with the photoresist layer or foaming generated by infiltration of plating bath into the photoresist layer is scarcely generated. As the formation is carried out on an optical disk matrix 14 in a good manner, grinding on the surface opposite to the side where recesses and projections are formed can be carried out with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for manufacturing a stamper for an optical disc.

[Technical Background of the Invention] In recent years, information recording media using high energy density beams such as laser beams have been developed and put into practical use. This information recording medium is called an optical disc, and includes video discs, audio discs, large-capacity still image files, and large-capacity computer discs.
It can be used as memory.

The basic structure of an optical disk is a disc-shaped transparent substrate made of plastic, glass, or the like, and a recording layer provided thereon. On the surface of the substrate on which the recording layer is provided,
In order to improve the flatness of the substrate, improve the adhesion to the recording layer, or improve the sensitivity of the optical disc, an undercoat layer or intermediate layer made of a polymeric substance is sometimes provided.

There are various types of optical discs, including a read-only type for the sole purpose of reproducing information, a write-once type in which information can be written, and a rewritable type in which previously recorded information can be rewritten.

Write-once and rewritable optical discs often have groups (pre-grooves, grooves) formed below the recording layer that serve as guide tracks. A disk in which only groups are formed before the recording layer is formed is generally called a replica disk. On the other hand, in a read-only optical disc, a plurality of bits (small holes) corresponding to digitized information are formed in advance on the surface of the substrate.

A replica disk on which these groups are formed or an optical disk substrate on which pits are preformed can be manufactured by injection molding, compression molding, or two-way molding using a mold equipped with a stamper.
It is molded by two methods.

Currently, stampers used for molding replica disks and optical disk substrates as described above are generally manufactured by the following method. That is, first, a photoresist layer is formed by coating and drying a photoresist coating solution on the surface of a support such as a glass plate, and after irradiating the photoresist layer of the obtained resist master with laser light, a development process is performed. A predetermined uneven pattern is formed on the surface of the photoresist layer. Next, the surface of the photoresist layer on which the unevenness has been formed is subjected to sputtering, electron beam,
A conductive film is formed using a thin film formation technique such as a resistance heating vapor deposition method, and then the conductive film is grown by an electroforming method to form an electroformed layer.

Next, the integrated conductive film and electroformed layer are removed from the photoresist layer to obtain a metal plate having an uneven pattern on its surface. This metal plate is a stamper for manufacturing optical discs.

In the manufacturing process of a general stamper for manufacturing optical discs as described above, a resist master on which a photoresist layer is formed is irradiated with laser light, and during development processing, the resist film may easily peel off or the conductive film may be electroformed. During the electroforming process in which the electroformed layer is grown by a method, the electroformed layer may partially lift off from the glass master along with the photoresist layer.
Further, phenomena such as foaming due to penetration of the plating solution were likely to occur. When such peeling occurs, the obtained stamper exhibits deformation or a decrease in precision, and becomes a defective product, making it unusable for practical use.

In order to solve the problem of peeling mentioned above, especially during the electroforming process, before forming the conductive film, the photoresist layer in the area other than the recording area (the area with the uneven pattern) of the photoresist layer on the glass master disk is A method for manufacturing a stamper for manufacturing an optical disc (JP-A-62-223838), in which a conductive film is formed on the photoresist layer in the recording area after removing the photoresist layer in the non-recording area on the inner peripheral side. A method for manufacturing a stamper for manufacturing optical discs in which only the photoresist layer is removed and a conductive film is formed on the photoresist layer in other areas (
JP-A-62-243146) has been proposed.

However, these methods require a step to remove photoresist located outside the recording area, which complicates the manufacturing process and increases manufacturing costs.

Furthermore, in order to solve the problem of the conductive film peeling off, a method for manufacturing a stamper for manufacturing optical disks has been proposed in which the conductive film is formed thickly (Japanese Patent Laid-Open No. 62-219251).
. However, even when the conductive film is formed thick, the problem still remains that the internal stress of the conductive film becomes high and the conductive film or the electroformed layer on which it is grown is likely to peel off from the glass master disk.

[Object of the invention] The present invention provides a highly accurate stamper for manufacturing optical discs.
Without introducing particularly complicated processes to conventional manufacturing methods,
The purpose is to provide a manufacturing method with high reproducibility (high yield).

[Summary of the Invention] The present invention provides a coating solution for forming a photoresist layer on the surface of a glass master disk, after drying, irradiating the resist master disk with laser light and performing a development process to form a coating solution on the surface of the photoresist layer. After forming a predetermined uneven pattern and then forming a conductive film on the uneven pattern on the surface of the photoresist layer, an electroformed layer is integrally formed on the conductive film, and this electroformed layer is combined with the photoresist layer. A method of manufacturing a stamper for manufacturing an optical disk, which comprises separating the stamper from a glass master, the surface of the glass master being subjected to ozone treatment before coating the surface of the glass master with a coating liquid for forming a photoresist layer. be.

Preferred embodiments of the method for manufacturing an optical disk stamper of the present invention are as follows.

1) Before applying the photoresist layer forming coating solution 3
The method for producing a stamper for an optical disc as described above, characterized in that the surface of the glass master is subjected to ozone treatment within 0 minutes.

2) Production of the optical disk stamper, wherein the ozone treatment is a treatment in which oxygen containing ozone gas with a concentration of 10 to 70 g/rr1' is injected at a flow rate of 5 to 15117 minutes for 5 to 300 seconds. Method.

[Effects of the Invention] The method for manufacturing an optical disk stamper of the present invention is characterized in that after the surface of the glass master disk is treated with ozone as described above, a coating liquid for forming a photoresist layer is applied and dried.

According to the present invention, the adhesion between the glass master and the photoresist layer can be improved by introducing ozone treatment, which is an extremely simple process in terms of both operation and time, into the manufacturing process. Therefore, it prevents peeling of the resist film during the development process, and also prevents the electroformed layer from floating together with the photoresist layer from the glass master, reducing thickness accuracy, and preventing foaming due to penetration of the plating solution into the photoresist layer. It is possible to prevent the peeling phenomenon that occurs. Thereby, it is possible to manufacture a highly accurate stamper for manufacturing optical discs with high reproducibility.

Furthermore, by introducing the ozone treatment process of the present invention,
Since the adhesion between the glass master disk and the photoresist layer can be ensured, the above ozone treatment can be used on any production line, and the use of the above ozone treatment increases the flexibility in the design of the production line. This has the advantage of being higher.

[Detailed Description of the Invention] In the manufacturing process of a stamper for manufacturing optical discs, the present inventor has discovered that the electroformed layer (and conductive film) and We have repeatedly investigated the causes of peeling of the photoresist layer from the glass master.

In the above-mentioned conventional technology, the adhesion between the glass master and the photoresist layer is not improved, and it is not possible to improve the adhesion between the glass master and the photoresist layer by directly adhering the conductive film and the glass master around the photoresist layer or by making the conductive film thicker. Attempts have been made to indirectly improve the adhesion between the glass master and the photoresist layer or to protect the photoresist. However, even if these methods are used in Group 1, the essential adhesion between the glass master and the photoresist layer is not improved, so the drawback that the photoresist layer easily lifts from the glass master still remains. Due to subtle differences in manufacturing conditions, the electroformed layer may float together with the photoresist layer, reducing thickness accuracy, or the plating solution may penetrate into the photoresist layer, causing foaming. I realized that I couldn't prevent it from happening.

Therefore, the present inventors further investigated ways to improve the adhesion between the glass master disk and the photoresist layer. Before applying photoresist, the surface of the glass master is generally polished and cleaned. Since these treatments require a relatively long time, the photoresist is usually applied the next day. However, the surface of the cleaned glass master disk becomes covered with an organic film over time, and such an organic film invalidates the initial activated state of the glass master surface. It has been found that it is necessary to remove such an organic film from the surface of the glass master disk and then apply a photoresist to improve the resistance. Furthermore, it has been found that ozone treatment, for example, injecting ozone gas onto the surface of the glass master, is extremely effective as a method for removing this.

Therefore, in the present invention, after the surface of the glass master is treated with ozone, a coating solution for forming a photoresist layer is applied and dried, followed by development treatment, formation of a conductive film, formation of an electroformed layer on the conductive film, and the like.
The method is characterized in that this electroformed layer is separated.

By introducing ozone treatment, which is an extremely simple process in terms of both operation and time, into the above manufacturing process, the adhesion between the glass master and the photoresist layer is improved, and therefore development processing is performed. It also prevents the electroformed layer from floating together with the photoresist layer from the glass master disk, reducing thickness accuracy, and preventing the plating solution from penetrating into the photoresist layer, causing foaming and peeling. This phenomenon can be prevented. Thereby, it is possible to manufacture a highly accurate stamper for manufacturing optical discs with high reproducibility.

Furthermore, by introducing the ozone treatment process of the present invention,
Since the adhesion between the glass master disk and the photoresist layer can be ensured, the above ozone treatment can be used on any production line, and the use of the above ozone treatment increases the flexibility in the design of the production line. This has the advantage of being higher.

The method for manufacturing a stamper for manufacturing an optical disk according to the present invention will be explained in detail with reference to FIGS. 1-A to 1-G, which illustrate typical embodiments.

FIG. 1-A is a sectional view of the glass master 11 on which an organic coating 12 has been formed on the surface several tens of minutes or more after the glass master 11 has been cleaned. For example, after removing the abrasive material, glass master disks can be cleaned using alkaline cleaning, acid cleaning, ultrasonic cleaning,
Then, cleaning with an organic solvent is performed alone or in an appropriate combination, and drying is performed with isopropyl alcohol, Freon vapor, or the like.

FIG. 1-B is a cross-sectional view of the glass master 11 shown in FIG. 1-A after the organic film 12 has been removed by injecting ozone gas onto the surface of the glass master 11. It is preferable to apply a photoresist coating liquid to the surface of the ozone-treated glass master 11 as soon as possible after the treatment. More preferably, the coating is applied within 30 minutes after the treatment, particularly preferably immediately after the treatment. This ozone treatment improves the adhesion between the glass master and the photoresist. This is because the organic film 12 is oxidized and decomposed by the ozone treatment, and for example, water,
This is presumed to be because it is removed as carbon dioxide gas and a hydrophilic glass surface appears.

The conditions for the above ozone treatment are such that after heating the glass master (preferably 200 to 300°C),
Oxygen containing ozone gas at a concentration of 0g/m''.
Preferably, the injection is performed for 5 to 300 seconds at a flow rate of iL/min.

FIG. 1-C is a sectional view of the resist master 10. FIG. The resist master 10 has, for example, a positive type photoresist layer 13 formed on the surface of a glass plate 11 serving as a support. In the photoresist layer of this resist master IO,
After being irradiated with a laser beam modulated by the information signal to be recorded, a development process (generally an alkaline aqueous solution is used) forms the structure shown in Figure 1-D in which a predetermined uneven pattern is formed. Optical disc master 14 having
is obtained.

Since the resist master 10 of the present invention has extremely excellent adhesion between the photoresist layer and the surface of the glass master, peeling of the resist film almost never occurs during the development process to form a predetermined uneven pattern. Never. Therefore,
The resulting optical disk master 14 can be said to have a predetermined concavo-convex pattern accurately formed on a glass master.

Next, a thin film 15 of a highly conductive metal such as nickel is formed as a conductive film on the surface of the optical disc master 14 shown in FIG. 1D on the side where the irregularities are formed by a method such as sputtering.
An optical disk master having the conductive film 15 shown in FIG. 1-E is obtained. At this time, the conductive layer is applied not only to the surface of the photoresist layer 13 but also beyond the side surface 13a of the support body so that the photoresist layer 13 does not come into contact with the outside world.
It is preferable to carry out the process up to point a (Fig. 1-E'). That is, by forming the conductive film to a position beyond the interface between the photoresist layer and the support, it is particularly effective to prevent the photoresist layer from coming into contact with the electroforming solution that may occur during the electroforming process.

FIG. 1-F is a sectional view showing a state in which the electroformed layer 16 shown in FIG. 1-E is further grown by electroforming. In the present invention, since the adhesion between the glass master and the photoresist layer is improved, the electroformed layer may float together with the photoresist layer from the glass master, resulting in a decrease in thickness accuracy and the plating on the photoresist layer. Peeling phenomena such as foaming due to liquid penetration hardly occur.

Therefore, since the electroformed layer 16 is well formed on the optical disc master 14 through the steps shown in FIGS. Polishing can be performed with high precision. Then, punching is performed on the inner and outer peripheries to obtain a stamper. For the above polishing, an abrasive such as alumina or alumina nitrate is used.

FIG. 1-G shows that the electroformed layer 16 formed on the optical disc master 14 is polished and separated from the optical disc master 14, and then punched on the inner and outer diameter sides to produce a stamper 17. It is a sectional view showing a state.

The method for manufacturing a stamper for manufacturing an optical disc explained in FIGS. 1-A to 1-G is a preferable method of manufacturing the present invention, and the present invention is directed to the above-described structure. It is not limited to. For example, the conductive film and the electroformed layer may be formed using a metal other than nickel.

The materials used in the method for manufacturing a stamper for manufacturing an optical disk according to the present invention will be briefly described.

Examples of the material for the glass master disc include soda lime, non-alkali glass, optical glass, and Pyrex. Soda lime glass is preferred from the viewpoint of price.

The photoresist material may be any material as long as it can be developed by irradiation with laser light. For example, positive type materials include AX series (Hoechst), Micro
Po5it series (Sibley), 0FPR series (Tokyo Ohka), and MPR series (Kodak)
etc. can be mentioned. Further, as a negative type material, for example, a quinone azide compound or a combination of a photodegrading agent and a phenol novolac can be used.

The following examples and comparative examples of the present invention will be described.

However, each of these aspects does not limit the present invention.

[Example 1] A soda-lime glass master polished to a mirror surface with an outer diameter of 240 mm and a thickness of 6 mm was cleaned with alkali. After -8, the surface of the glass master was heated with 20 g/rn' of oxygen containing ozone gas at 81/min. Ozone treatment is carried out by spraying at a flow rate of
A photoresist layer with a thickness of 100 mm was provided. The resulting resist master is exposed (cut) to laser light,
A pattern was formed on the surface by developing with an alkaline aqueous solution. Next, a Ni conductive film with a thickness of 125° was formed on the pattern on the surface by sputtering Ni, and then Ni plating was performed on the conductive film to form a 30° thick Ni conductive film.
An electroformed layer of 0 μm was integrally formed, and then the back surface of the electroformed layer was polished to a mirror surface using Cerox as an abrasive, and this electroformed layer was separated from the photoresist layer to create a stamper.

[Comparative Example 1] A stamper was produced in the same manner as in Example 1 except that the ozone treatment was not performed.

1) Lifting of the electroformed layer 2) Peeling of the electroformed layer 3) Penetration of abrasive during backside polishing Regarding the above three points, after forming the Ni conductive film, the presence or absence of cracks during electroforming was observed.

As a result, in Example 1, the above-mentioned lifting, peeling, etc. did not occur, but in Comparative Example 1, many occurred. It was also observed that the peeling interface was between the glass master and the photoresist.

Therefore, it can be seen that the ozone treatment of the present invention is effective in preventing the occurrence of floating, peeling, etc.

[Brief explanation of the drawing]

1-A to 1-G are schematic diagrams for explaining the method of manufacturing a stamper for manufacturing an optical disk according to the present invention. 10: 11: 1a 12: 13 = 3a 14: 15: 16 = 17 Two-resist master Glass master Two Glass master Side organic coating Photoresist layer: Photoresist layer Side Optical disk master Conductive film layer Electroformed layer Stamper

Claims (1)

[Claims] 1. After applying and drying a coating liquid for forming a photoresist layer on the surface of a glass master disk, the resist master disk is irradiated with laser light and developed to form a predetermined uneven pattern on the surface of the photoresist layer. A stamper for an optical disc, which comprises forming a conductive film on the uneven pattern on the surface of the photoresist layer, integrally forming an electroformed layer on the conductive film, and separating the electroformed layer from the photoresist layer. A manufacturing method characterized in that the surface of the glass master is subjected to ozone treatment before applying the photoresist layer forming coating liquid to the surface of the glass master.