JP3196259B2 - Polishing 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 polishing a stamper for an optical disk.

[0002]

2. Description of the Related Art Optical disks are characterized by their large capacity and high recording density compared to floppy disks and hard disks, and are being actively researched and developed at present. In general, substrates for optical disks are produced by injection molding so that mass production is possible while maintaining the above-mentioned excellent characteristics. At this time, grooves and pits formed on the stamper are transferred to the optical disk. Therefore, the above stamper is required to have high precision as a mold and durability during injection molding.

[0003] The conventional method of manufacturing a stamper for an optical disk is performed by the following method, for example. That is, a resist is uniformly applied to a required thickness on a glass substrate having a polished surface by a spin coating method, and after prebaking, after exposing to a desired pattern by a laser cutting machine, the resist is developed to form pits and / or grooves. I do. A thin film of nickel or the like is coated on the surface of the resist-coated glass substrate having the pits and / or grooves by a sputtering method or the like to maintain conductivity, and nickel of an arbitrary thickness is deposited by electroforming. Subsequently, nickel is separated from the glass substrate and washed. Thereafter, the back surface is polished and washed, and then the inner and outer diameters are processed to complete the stamper.

A stamper is required to have high precision as a mold and durability during injection molding.
The step of polishing the back surface of the stamper becomes important. Until now, it has been mainly performed by a self-revolution type polishing method using a mechanochemical polishing agent mainly containing an abrasive and a chemical etching agent. However, in this method, it is difficult to control the amount of polishing of the stamper, and there are problems such as the occurrence of minute projections and minute dents due to slight fluctuations in the amount of abrasive supplied.

On the other hand, recently, a polishing method has been used in which a polishing tape is moved in a radial direction while pressing the polishing tape against the back surface of a rotating stamper. However, there is a problem that it is difficult to control the warpage of the stamper.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to manufacture a stamper for an optical disc having high precision and high durability as a mold for injection molding. To provide a polishing method.

[0007]

The present inventors have made intensive studies to solve the above problems, and as a result, completed the present invention by dividing polishing of the back surface of the stamper for an optical disk into two steps. I came to.

That is, the present invention comprises a polishing step 1 in which the polishing tape is moved in the radial direction while pressing the polishing tape against the back surface of the rotating stamper, and a polishing material and a chemical etching material subsequent thereto. A method of polishing a nickel stamper for an optical disk, comprising a self-revolution type polishing step 2 using a mechanochemical polishing material.

Hereinafter, the present invention will be described in detail.

The type of the polishing tape used in the polishing step 1 does not need to be a special type. However, alumina, diamond, etc. are used because of the stability and low chemical reactivity of the product. It is desirable to use one having a main component, and the material of the base film and the width thereof are not particularly limited. The winding speed of the polishing tape depends on the size of the abrasive, but is 5 to 50 cm.
/ Min. The rotation speed of the stamper is preferably 50 to 2000 rpm, although it depends on the winding speed of the polishing tape or the moving speed of the stamper in the radial direction. Regarding the moving speed of the stamper in the radial direction, although it depends on the width of the polishing tape, 1 to 50 mm /
Desirably seconds.

The polishing time is desirably set arbitrarily according to the roughness of the back surface of the stamper. If these conditions are out of the range, the warpage of the stamper will increase, and the reproducibility of the polishing margin will deteriorate. Further, a method of discharging a grinding liquid instead of a tape with abrasive grains may be used.

As the abrasive used in the polishing step 2, it is desirable to use an abrasive mainly composed of alumina and diamond for the above-mentioned reason. The dilution rate is 0 to 1
It is preferably in the range of 00%, and the supply amount is preferably 5 to 100 cc / min, depending on the dilution ratio. The rotation speed of the stamper and the rotation speed of the pad are preferably 5 to 100 rpm depending on the dilution ratio and supply amount of the abrasive. The polishing time is arbitrarily set so as to obtain the roughness and thickness required for injection molding. If these conditions are out of the range, in addition to the above-described problems, problems such as minute protrusions or minute depressions on the polished surface also occur.

[0013]

The present invention will be described in more detail with reference to Examples, but it should not be construed that the invention is limited thereto.
Example 1 A signal surface of a stamper obtained by electroforming was protected with a polymer film containing polyvinyl acetate and polyvinyl chloride as a main component, and a fixing hole was formed in the center, and the taper was fixed to a tape polishing machine. did. Using a 1-inch wide tape mainly composed of alumina, the stamper was wound at a winding speed of 20 cm / min.
Polishing was performed at a rotation speed of the stamper of 100 rpm and a moving speed of the stamper in the radial direction of 20 mm / sec for 5 minutes.

Subsequently, the stamper was removed from the tape polishing machine, and attached to a jig of a self-revolving polishing machine using a double-sided adhesive tape. The stamper was subjected to mechanochemical polishing using an undiluted abrasive mainly composed of alumina at a supply rate of 20 cc / min. This allows
There was no small protrusion or small depression on the polished surface, and a stamper with small warpage was obtained.

[0015]

As is apparent from the above description, according to the present invention, it is possible to manufacture a stamper for an optical disc having a high degree of accuracy and a high durability as a mold for injection molding. become.

Continuation of the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/26 B29C 33/38 B24B 1/00 B24B 21/00 B24B 37/00

Claims (1)

(57) [Claims] In a method of polishing a back surface of a stamper for an optical disk, a polishing step 1 in which a polishing tape is moved in the radial direction while being pressed against a back surface of a rotating stamper, and a polishing material and a chemical etching subsequent thereto A polishing method for a stamper for an optical disk, comprising: a self-revolution type polishing step 2 using a mechanochemical polishing material composed of a material.