JPH02307737A - Method for washing stamper for optical disk - Google Patents

Abstract

PURPOSE:To eliminate the flaw of an optical disk generated by the change of the surface state of a stamper as the number of optical disks due to injection molding increases and to enhance the yield of injection molding under the same molding condition by the same stamper by performing wet washing due to an org. solvent before performing dry washing. CONSTITUTION:A stamper changed in the surface state by injection molding and generating an optical disk inferior in characteristics is immersed in a bath tank receiving methylene chloride 2 and ultrasonic washing is used together. Next, the stamper is taken out of the bath tank and immersed in a bath tank receiving methyl ethyl ketone or acetone 3 before methylene chloride 2 adhered to the stamper is dried and ultrasonic washing is used together. Next, the stamper is taken out of the bath tank is immersed in a release liquid 4 of a positive type resist, for example, a liquid pyrrodlidones or piperazines at 60 - 200 deg.C before methyl ethyl ketone or acetone 3 adhered to the stamper is dried and ultrasonic washing is used together. Thereafter, the stamper 1 is cooled to about room temp. in the release liquid and transferred to ultrapure water 5 in the vicinity of room temp. and ultrasonic washing is used together. Next, the stamper 1 is drained and, after drying, ashing due to oxygen plasma 6 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for cleaning an optical disk stamper for modifying the surface condition of a stamper during use in an optical disk manufacturing process by injection molding.

[Prior Art] Conventionally, as the number of injection moldings increases in the optical disk manufacturing process, the surface condition of the stamper changes, and a cloudy pattern or a streak-like pattern gradually appears on the appearance of the optical disk. When this defect occurred, the molding conditions were changed and an optical disk with good characteristics was obtained.

[Problems to be Solved by the Invention] However, in the above-mentioned solution by changing the molding conditions, the molding conditions are changed only after an optical disk with visually discernible poor appearance characteristics occurs. In this case, an optical disk whose mechanical and electrical characteristics are out of tolerance occurs in the optical disk immediately before the appearance characteristic defect occurs. Therefore, if the molding conditions are changed after an optical disk with poor appearance characteristics occurs, optical disks with poor appearance and optical disks with poor mechanical and electrical characteristics will be produced, which will cause a decrease in yield. ing. In addition, when changing molding conditions, temperature,
Injection speed, injection pressure, etc. are changed, but until these factors are changed and molding conditions that provide good characteristics and no optical defects are determined, production is halted, resulting in a decrease in productivity. Furthermore, the durability of the stun glue will decrease due to the number of times injection molding is performed to set the molding conditions, and if the molding conditions are changed to a polyhydric type.
There is a problem that an optical disk with good characteristics cannot be obtained even after such studies. In addition, if another stamper is subsequently used after changing the molding conditions, it is necessary to reset the molding conditions, and there is also the problem that the yield rate decreases due to factors such as setting errors by the operator.

The present invention is intended to solve these problems, and its purpose is to eliminate defects in optical discs that occur due to changes in the stamper surface condition as the number of injection molded discs increases, and to eliminate defects in optical discs that occur when the stamper surface condition changes as the number of injection molded discs increases. The aim is to improve the yield of injection molding at the bottom.

[Means for Solving the Problems] The optical disk stamper cleaning method of the present invention is characterized by performing wet cleaning with an organic solvent and then dry cleaning.

[Example] The method of cleaning a stamper for an optical disk according to the present invention is basically a process shown in FIG. The present invention will be described below based on examples.

First, during injection molding, mold release agents and heat stabilizers adhere to the surface extremely thinly, making the surface condition different from before injection molding, resulting in optical discs with poor appearance characteristics and optical disks with poor mechanical and electrical properties. The stamper that became the first
Immerse it in a bath containing methylene chloride for at least 60 seconds as shown in Figure a.

Ultrasonic cleaning is also used depending on the degree of use of the stamper. The liquid temperature should be around room temperature. Next, remove the stan glue from the methylene chloride bath, and before the methylene chloride adhering to the stan glue dries, immerse it in a bath containing methyl ethyl ketone or acetone for at least 30 seconds as shown in Figure 1. Ultrasonic cleaning is also used depending on the degree of use of the stamper. The liquid temperature should be around room temperature. Next, the stamper is taken out of the methyl ethyl ketone acetone bath, and before the methyl ethyl ketone or acetone adhering to the stamp dries, it is immersed in a positive resist stripping solution, such as a pyrrolidone or piperazine liquid, as shown in FIG. 1C. At this time, the liquid is 60℃ ~
It is heated to 200°C. The immersion time is 1 minute or more, and ultrasonic cleaning is also used depending on the degree of use of the stamper. After this, the stamper is cooled down to around room temperature in a stripping solution, and then
Transfer it to ultrapure water near room temperature or remove it from the stripping solution for 60 minutes.
The sample is transferred to ultrapure water at a temperature of 90°C to 90°C, and then to ultrapure water at around room temperature (Fig. 1d). The immersion time in this ultrapure water near room temperature is 3 minutes or more. Ultrasonic cleaning is also used depending on the degree of use of the stamper. Next, the stamper is drained and dried, and then oxygen plasma ashing is performed as shown in FIG. 1C. Ashing conditions vary depending on the machine used, so as a guide, the conditions are oxygen pressure 118tOr.
r, power 300W', time 6 minutes, chamber temperature 45
The temperature should be below °C. By cleaning the stamper as described above, the condition of the stamper surface becomes the same as the condition of the stamper surface before molding, and defects in optical disks that occur due to changes in the surface condition of the stamper after a certain number of injection molding operations are performed. It has the effect of preventing the occurrence of.

[Effects of the Invention] According to the method for cleaning a stamper for an optical disk of the present invention, a stamper whose surface condition has changed due to injection molding, resulting in an optical disk with poor characteristics, can be removed by changing the injection molding conditions or setting the conditions. Even without this, the stamper surface condition can be made such that an optical disc with good characteristics can be obtained. By periodically performing this stamper cleaning after a certain number of injection moldings, it is possible to improve the yield of optical disks of the stamper, improve productivity, and increase the number of molded stampers that can last for a long time.

[Brief explanation of drawings]

FIG. 1 (L % e is a process diagram of an embodiment of the optical disc stamp cleaning method of the present invention. 1 Stamper 2 Methylene chloride 6...・・・・・・Methyl ethyl ketone or acetone 4・・・・・・Positive resist stripper 5・
・・・・・・・・・Ultra pure water 6・・・・・・・・・Oxygen plasma and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (1 other person) I-rSJ
(G) φshi)
-Muini

Claims (1)

[Claims] A method for cleaning a stamper for an optical disk, characterized in that changes in the state of the stamper surface before and after injection molding are improved by wet cleaning with an organic solvent and dry cleaning.