JP3221627B2 - Manufacturing method of stamper for optical disk - Google Patents

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 a stamper for an optical disk having high moldability.

[0002]

2. Description of the Related Art A conventional method of manufacturing a stamper for an optical disk will be described with reference to FIG. Optically polished glass master 1
After cleaning 1 (FIG. 2A), a photoresist layer 12 is formed on the glass master 11 (FIG. 2B). The photoresist layer is exposed to laser light 13 corresponding to a signal to be recorded. By developing and removing the exposed portion, minute irregularities are formed (FIG. 2C).
A conductive film 14 necessary for electroplating is provided on this surface by, for example, a sputtering method using nickel (FIG. 2D). Thereafter, nickel electroforming is performed using the electrode as an electrode, and the glass master disk 11 is peeled off to obtain a stamper master plate 15 for an optical disk (FIG. 2E). Here, the photoresist remaining film 16 remains on the stamper original plate 15 for the optical disk when the glass master 11 is peeled off. The remaining photoresist film is usually dissolved and removed using an organic solvent. If the photoresist remaining film 16 attached to the optical disk stamper original plate 15 is not completely removed, irregularities due to the remaining photoresist remaining film are transferred to the substrate during injection molding, and the C / N of the obtained optical disk is greatly reduced.
When a conductive film is formed by a sputtering method using nickel, it is difficult to completely remove a photoresist remaining film remaining on an optical disk stamper with an organic solvent due to deterioration of the surface of the photoresist layer. In many cases, a method of completely removing the photoresist remaining film 16 remaining on the stamper original plate by performing a plasma cleaning process (FIG. 2F) is adopted. After removing the remaining photoresist film, perform shaping of the outer periphery, etc.
The stamper 17 for an optical disk is completed (FIG. 2G).
This optical disk stamper 17 is attached to a molding die,
The irregularities of the stamper are transferred to the resin substrate 18 by an injection molding method (FIG. 2 (h)), and a reflection film, a recording film 19 and the like 19 are formed on the signal surface by a vapor deposition method or the like (FIG. 2 (i)). Protective film 2
By adding 0, an optical disc having a concavo-convex pattern corresponding to signals such as address information and video / audio signals on the substrate surface is completed.

[0003]

However, when injection molding is performed using the stamper for an optical disk manufactured by the above-described method, a site having strong activity is generated on the surface of the stamper by the above-described plasma cleaning treatment, and the strong adsorption action is generated. Thereby, the hydroxyl groups in the release agent contained in the resin used for injection molding are easily bonded to the surface of the stamper for an optical disk. As a result, the release agent gradually adheres to the stamper for the optical disk during the injection molding, the adhesiveness between the resin and the stamper is deteriorated, and the transfer of the unevenness of the stamper is not performed well. In particular, when the mold is opened and closed in the injection molding process, the formed substrate is spontaneously peeled off from the optical disk stamper, and therefore, the irregularities on the optical disk stamper may be shifted and transferred, especially on the outer periphery (hereinafter, referred to as “hereafter”). This phenomenon is called “demold failure”.) Also, once the release agent adheres to the surface of the optical disk stamper, even if the injection molding conditions are changed, the occurrence of mold release failure does not disappear, and it is not possible to obtain a substrate on which the irregularities of the optical disk stamper are accurately transferred. Have difficulty.

An object of the present invention is to provide a method of manufacturing a stamper for an optical disk which does not cause a release agent to adhere to the surface of the stamper for an optical disk even if injection molding is continuously performed, and does not cause a release failure. .

[0005]

The objects of the present invention are as follows: (a) a step of forming a photoresist layer on a glass master; and (b) a step of exposing and developing the photoresist layer to form irregularities in the photoresist layer. (C) a step of forming a conductive film on the photoresist layer, (d) a step of forming a stamper master by an electroforming method using the conductive film as an electrode, and then peeling the glass master, and (e) forming a stamper master. The remaining photoresist film on the surface is treated with a weak alkaline solution to remove the stamper
This is achieved by the method of manufacturing a stamper for an optical disc according to the present invention, which comprises a step of leaving a thin film of photoresist on the surface of the plate .

[0006]

Hereinafter, a method for manufacturing an optical disk stamper according to the present invention will be described with reference to FIG. After cleaning the optically polished glass master 1 (FIG. 1A), a photoresist layer 2 is formed on the glass master 1 (FIG. 1).
(B)). The photoresist layer 2 is exposed by irradiating a laser beam 3 corresponding to a signal to be recorded. By developing and removing the exposed portion, fine irregularities are formed (FIG. 1C), and a conductive film 4 necessary for electroplating is provided on the surface of the photoresist layer 2 by a sputtering method using nickel (FIG. 1C). 1 (d)). Using this as an electrode, nickel electroforming is performed to obtain an original stamper plate 5 for an optical disk (FIG. 1 (e)). The glass master 1 and the optical disk stamper master 5 are peeled off. At this time, the photoresist remaining film 6 remains on the surface of the stamper original plate 5 for an optical disk (FIG. 1).
(F)). The stamper original plate 5 for the optical disc with the remaining photoresist film is immersed in a weak alkaline solution 7 (for example, a commercially available registry mover) using a thermostat, and the photoresist remaining film 6 remaining on the original stamper plate 5 for the optical disc.
Is gradually decomposed (FIG. 1 (g)) . When the conductive film 4 is provided by the nickel sputtering method, the interface between the original stamper plate and the photoresist layer is deteriorated.
Is not completely dissolved in the weak alkaline solution, leaving an extremely thin photoresist thin film 8. Through a process such as shaping of the outer periphery, a stamper for an optical disk having an extremely thin photoresist thin film 8 is completed (FIG. 1 ( h )).

As the weak alkaline solution used in the present invention, a commercially available registry remover is preferably used.
In use, it is desirable to use the weak alkaline solution at a temperature of about 50 ° C. in order to enhance the removal ability and shorten the processing time. The processing time is desirably 2 to 5 minutes.

[0008] The stamper for an optical disk according to the present invention and the stamper for an optical disk from which the photoresist thin film on the surface has been completely removed by a plasma cleaning process are mounted on a mold, respectively, and are released when injection molding is performed using a polycarbonate resin. Table 1 shows a comparison of the occurrence of defects. As shown in Table 1, the case where the stamper for an optical disk according to the present invention was used was compared with the case where the stamper from which the photoresist thin film was completely removed by the plasma cleaning treatment was used.
Less occurrence of mold release failure.

[Table 1]

In general, when a photoresist thin film is present on the surface of a stamper as in the present invention, signal information such as address information and video / audio signals recorded on an optical disk stamper is affected by the unevenness of the photoresist thin film. It is considered that there is deterioration. Therefore, the CD manufactured according to the present invention
And a plasma cleaning process for the stamper,
Table 2 shows the results of comparative inspection using a CD stamper inspection machine with a CD stamper from which the photoresist thin film was completely removed.
Shown in As shown in Table 2, there is almost no difference in signal characteristics between the CD stamper according to the present invention and the CD stamper from which the photoresist thin film has been completely removed. This indicates that the photoresist thin film remaining on the optical disk stamper manufactured according to the present invention does not affect signals such as address information, video and audio signals engraved on the optical disk stamper. I have.

[Table 2]

[0010]

As described above, according to the present invention, the mold release agent contained in the resin used for the injection molding does not adhere to the surface of the stamper even if the injection molding is continuously performed. A stamper for an optical disc is manufactured that does not reduce the adhesion of the optical disk and does not cause a release failure.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing an optical disk stamper according to the present invention.

FIG. 2 is an explanatory view of a conventional method for manufacturing a stamper for an optical disc.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 glass master 2 photoresist layer 4 conductive film 5 stamper master 6 photoresist remaining film 7 weak alkaline solution 8 photoresist thin film

Claims (1)

(57) [Claims] (A) forming a photoresist layer on a glass master; (b) exposing and developing the photoresist layer to form irregularities on the photoresist layer; and (c) on the photoresist layer. (D) forming a stamper master by electroforming using the conductive film as an electrode, and then removing the glass master; and (e) removing the photoresist remaining film remaining on the surface of the stamper master. Treat with a weak alkaline solution and apply it to the surface of the original stamper
A method for manufacturing a stamper for an optical disc, comprising a step of leaving a thin film of a photoresist .