JPH0630172B2 - Method for manufacturing stamper for optical disk - Google Patents

Description

Description: (a) Technical Field of the Invention The present invention relates to a method for manufacturing a stamper for an optical disc having a low defect density.

(B) Background of technology The optical disc is capable of recording a large amount of information, and can record and reproduce information in a non-contact state with the disc surface, and is not easily affected by dust. It is a memory.

In other words, a magnetic disk or magnetic tape requires an area of several tens of square μm for recording 1-bit information, whereas an optical disk condenses laser light into a minute spot with a diameter of about 1 μm for recording. Is about 1 square μm, and a large capacity recording is possible.

Further, since the distance from the lens end surface of the laser light focused by the objective lens to the disk surface is 1 to 2 mm, the risk of head crash, which is a problem with magnetic disks, can be avoided, and therefore the life can be extended. .

Since the recording / reproducing laser beam is focused through a transparent cover with a thickness of about 1 mm, the recording medium is not exposed, so that contamination can be avoided and a spot with a diameter of about 1 μm has a diameter on the transparent cover. Since the light beam is about 1 mm, the presence of dust has almost no effect.

The present invention relates to a method of manufacturing a stamper used when manufacturing an optical disc having such characteristics.

(C) Prior Art and Problems FIG. 1 shows a manufacturing process of an optical disk stamper.

Well-polished thickness is about 5mm and diameter is 20-40cm
Using the glass disk as a substrate, a resist film 2 is formed on the substrate 1 by spin coating as shown in FIG.

Next, a laser beam is selectively applied to the pre-groove position and the address position such as the track No. and the sector No. to expose the resist film 2 to light, and by developing this, the pre-groove master shown in FIG. 3 is completed.

Next, as shown in FIG. 2C, a nickel (Ni) vapor deposition film 4 having a thickness of several hundred Å is formed on the pre-groove master 3 by the vacuum vapor deposition method, and further on the vapor deposition film 4 shown in FIG. ), The thickness is about 30 by electrolytic plating (hereinafter abbreviated as plating) method.
A Ni layer 5 of 0 μm is formed.

The Ni layer 5 thus produced is peeled from the pre-groove master 3 shown in FIG. 6B to complete the stamper 6 as shown in FIG.

The stamper 6 made in this way uses this as a mold,
An optical disc is manufactured by molding a synthetic resin by a method similar to that of record production and forming a recording medium layer on the synthetic resin plate.

The present invention relates to a method of manufacturing a stamper used for forming such an optical disc.

Here, the necessary condition of the stamper 6 is that the information such as the pre-groove and the address formed on the resist film 2 is reproduced with high accuracy as shown in FIG. The position, for example the pre-groove position, must be flat and free of defects.

The reason for this is that if unevenness exists on the surface of the recording medium, the laser light is diffusely reflected during reading, noise increases, and the information quality is significantly impaired.

Therefore, in order to improve the adhesion with the resist film 2 in the step of forming the Ni vapor deposition film 4 on the resist film 2 shown in FIG. The substrate 1 is being heated.

However, when Ni is vapor-deposited while heating the substrate in this way, volatile components are generated from the resist film 2 and are mixed in the Ni vapor-deposited film 4, and the resist film 2 and the Ni vapor-deposited film 4 may react with each other. The Ni vapor-deposited film becomes water repellent due to the occurrence of such a phenomenon, and the Ni layer 5 is formed in the subsequent Ni plating step.
And the Ni vapor-deposited film 4 have incomplete adhesion. Therefore, to form the stamper 6, the Ni layer 5 is formed on the pre-group master 3
There is a problem that a part of the Ni vapor deposition film 4 remains on the resist 2 when it is peeled off from the resist, so that the stamper 6 has a large number of defects.

As a solution to this problem, it is conceivable to wash the film surface with a solvent after forming the Ni vapor-deposited film 4, but the Ni vapor-deposited film 4 is thin and the resist is easily dissolved in a general solvent. Therefore, there is a problem that surface treatment such as cleaning cannot be performed.

(D) Object of the Invention An object of the present invention is to provide a method for forming a Ni plating layer by removing the water repellency of a Ni vapor deposition film formed on a pre-groove master in manufacturing an optical disk stamper.

(E) Structure of the invention The purpose of the present invention is to form a nickel vapor deposition film on a pre-groove master of an optical disc, and then immerse the master in a nickel plating solution and rotate it to restore the wettability of the nickel vapor deposition film. This can be achieved by a method for manufacturing an optical disk stamper characterized by performing nickel electroplating after performing pretreatment.

(F) Embodiments of the Invention In manufacturing the stamper 6, it is necessary to reduce defects on the molding surface as much as possible. From this viewpoint, heating the substrate 1 for improving the adhesion in forming the Ni vapor deposition film 4 is necessary.

However, this heat treatment causes water repellency in the Ni vapor deposition film 4.

The inventors of the present invention, as a method of removing water repellency without performing solvent treatment, immerse a pre-groove master (hereinafter abbreviated vapor deposition substrate) having a Ni vapor deposition film 4 shown in FIG. 1C into a Ni plating liquid. Then, it was found that the water repellency can be removed by performing the rotation treatment.

However, the removal of this water repellency is not essential, and the original water repellency will appear again if it is washed with water and then dried. The reason for this is not clear, but probably the surfactant added to the plating solution is deposited on the surface of the deposition substrate due to the potential difference between the Ni deposition film and the plating solution and the stirring effect due to rotation, causing the water repellency to disappear. It seems that

However, rotation of the vapor deposition substrate in the liquid is not effective in a short time,
It is necessary to do it for at least several tens of minutes.

By this method, the adhesion between the vapor-deposited substrate and the Ni-plated layer is improved, and when the Ni layer 5 shown in FIG. 1 (D) is peeled off to form the stamper 6, defects due to the remaining Ni-vapor-deposited film 4 are eliminated. be able to.

Examples will be described below.

The substrate heating temperature when forming the Ni vapor deposition film on the pre-groove master was 140 ° C, and the vapor deposition was performed under these conditions to obtain a 500 Å thick N film.
i Deposited film 4 was formed.

This vapor-deposited substrate was immersed in a commercially available nickel plating solution containing nickel sulfamate as the main constituent, and rotated at 100 RPM.
The stamper 6 was made by rotating each other for 40 minutes and then plating by a normal method, but the defect density is about 10, which is far smaller than the conventional one.

FIG. 2 shows the relationship between the defect density of the stamper and the immersion time. The number of defects was measured from the abnormality of the reflected light when the surface of the stamper was scanned with a laser spot.

The rotation of the deposition substrate is 100 RPM, but the characteristic curve 7
As is clearer, the defect density decreases with the immersion time and approaches a constant value.

Here, the defect density is a count of all the defects generated on the stamper surface, and no peeling defect of the Ni vapor deposition film is found at the saturation value of the characteristic curve 7.

As described above, the stamper defects can be reduced by performing the simple process of rotating the vapor deposition substrate in the liquid.

(G) Effect of the Invention The present invention removes the water repellency that occurs when the substrate is heated to improve the adhesion of the Ni vapor deposition film to the pre-groove master. It will be possible.

[Brief description of drawings]

1 (A) to 1 (E) are cross-sectional views showing a manufacturing process of an optical disk stamper, and FIG. 2 is a relationship diagram of the stamper and the immersion time. In the figure, 1 is a substrate, 2 is a resist, 3 is a pre-groove master, 4 is a nickel vapor deposition film, 5 is a nickel layer, and 6 is a stamper.

Claims (1)

[Claims] 1. After forming a nickel vapor deposition film on a pre-groove master of an optical disc, the master is immersed in a nickel plating solution and rotated to perform a pretreatment for recovering the wettability of the nickel vapor deposition film. , A method for manufacturing a stamper for an optical disk, which comprises electroplating nickel.