JPH01279437A - Master disk for manufacturing optical disk, its manufacture and forming body for optical disk - Google Patents

Abstract

PURPOSE:To smooth the flow of a resin at forming in the case of forming a resin forming base by selecting horizontal asymmetry to the shape of cross section of a master disk of a recessed part corresponding to a tracking slot or an address pit in radial direction. CONSTITUTION:After an adhesives is coated on a glass substrate, a photosensitive resist is further coated. Then the substrate irradiated by a laser beam to expose it. After the exposure, the base is developed to form a resist pattern having a cross sectional shape as shown in figure. Based on the base formed in this way, a stamper is obtained. The optical disk medium forming body is produced by using the stamper. In case of forming the master disk, the cross section of the recessed part corresponding to the tracking slot or the address pit is formed horizontally asymmetrically. The flow of resin in forming is smoothed by using the stamper based thereupon and a forming body for an optical disk with an excellent optical characteristic is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molded body for an optical disk medium, a master disc for manufacturing a stand bar used in molding the molded body, and a method for manufacturing the master disc.

(Prior Art) Optical discs have tracking guide grooves and address pits on their substrates. The stand bar used for manufacturing such optical discs is shown in FIGS. 6(a) to (e).
Usually, one fabrication is performed according to the steps shown in the cross-sectional view. That is, first, the coupling agent 2 and the photoresist 3 are placed on the glass plate 1 by r? IHL/ [Figure, (a)] This is partially exposed to laser light and then developed to form a pattern on the resist, which is used as a master.
(b)]. Next, a metal film 4 such as N1 is provided on this master by a method such as sputtering [(C)], and then
Form the i-plated layer 5 [(d)]. In this way, the stamper is produced. The energy component Iiii of the beam cross section of the laser beam used in this manufacturing process is shown in Figure 1(a).
As in, we hit a Gaussian distribution. Therefore, the four-part cross-sectional shape of the pattern of the optical disk stand bar obtained by the L distribution method is symmetrical as shown in FIG. 2(a).

[Problem to be solved by the invention]

However, when using such a stamper to obtain a resin-molded substrate as shown in FIG. 1(e) by injection molding, the resistance to the resin flow increases on the surface of the stamper for optical discs. . As a result, the flow of the resin becomes poor, making it difficult to reduce the birefringence of the TiSF, and optical properties such as poor appearance due to the turbulent flow of the resin deteriorate. In addition, injection molding has poor transferability of the stamper shape to the resin molded substrate, so the shape is not accurately transferred and the molding J.
The c-plate has a shape different from the stanbar shape. For this reason, it will have an adverse effect on the first order signal.

In the present invention, by using exposure with a high-density beam having an asymmetrical distribution, the cross-sectional shape of the four parts corresponding to the tracking grooves or address pits is as shown in FIG. 1(b).
A stamper based on this master is used to suppress the flow resistance of the resin during molding, providing a molded body for optical disc media with excellent optical properties, and as a result, high-quality playback. This is an attempt to extract a signal.

(Means for Solving the Problems) The present invention provides that after laminating a photosensitive layer on a substrate-L, the photosensitive layer is
It is a method for manufacturing a master disc that includes a step of exposing with a high-density beam having a cross-sectional energy distribution or a non-Gaussian distribution, and then developing it, and the master disc made by this manufacturing method, that is,
A master disc is characterized in that a photosensitive layer is provided on a substrate to form recesses corresponding to tracking grooves or address pits, and a cross-sectional shape of the recesses in a radial direction of the master disc is asymmetrical, Furthermore, the present invention provides a molded article for an optical disc that can be manufactured using the master disc, that is, a molded article for an optical disc having a tracking groove or an address pit, in which the tracking groove or the address pit has a
The molded body is characterized in that the radial cross-sectional shape of the master is asymmetrical.

Hereinafter, embodiments of the present invention will be described.

Apply adhesive, such as AZ-80, PRO, on the glass substrate.
After coating with a silane coupling agent such as M0TER-100 (trade name, manufactured by Hoechst), a photosensitive resist [AZ-1:150 (trade name) manufactured by Hoechst, etc.] is further coated. Next, the substrate is exposed to laser light. The laser beam used has a cross-sectional energy distribution as shown in FIG. 1(b). By developing after exposure, a resist pattern having a cross-sectional shape as shown in FIG. 2(b) can be formed. For example, Ni is sputtered onto the master disc thus prepared, and then Ni plating is applied. Thereafter, a stand bar is obtained by peeling off the Ni layer. By using this standber in a molding method such as injection molding or injection compression molding, molded bodies for optical disk media can be produced in large quantities.

As shown in Figure 2 (b), when the center of the bottom of the recess corresponding to the tracking groove or address pit is on the inner circumferential side than the center of the side parallel to it, the flow of resin during molding will be smooth. Therefore, a molded product with good optical properties such as birefringence can be obtained.

By changing the energy distribution during exposure and changing the development conditions, it is possible to create grooves whose cross-sectional shapes are defined by curves with many inflection points as shown in Figures 3(a) to (c). Bits can be formed.

Further, in the embodiment described in (1), the cross section of the groove is an asymmetrical trapezoidal shape, but it may also be an asymmetrical U-shape or (3) shape, and the same effects can be obtained with these.

For example, the method of giving energy distribution to a light beam is as follows.
As shown in Figure 4, there are pinholes and slits 7 in the optical beam path.
This can be done by cutting the beam.

〔Example〕

Example 1 A silane coupling agent was coated on a glass substrate, and then a photosensitive resist 8Z-1350 was coated to a thickness of 1450 mm. Next, the substrate was partially irradiated with Ar laser light. The output is 200 mW, and the output is about 20 mW in the exposed part because it is cut in the optical path.

Through the process described in F, a resist pattern having a shape as shown in FIG. 5 was formed.

Sputter Ni onto the obtained master to a thickness of 500 to 20
00 people), then Ni plating treatment (thickness 20.3~0.00).
6+nm), by peeling off the Ni layer,
Got a standby. Using this standber, an optical tisf medium was produced by an injection molding method.

Comparative Example 1 An optical disc medium was produced in the same manner as in Example 1, except that a laser beam with a Gaussian distribution was used in the exposure process during master production.

(Evaluation) In Example 1, the birefringence was small, and in Comparative Example 1, the birefringence was large. Furthermore, similar signals were obtained for both tracking signals and address signals.

〔Effect of the invention〕

As explained in detail below, by controlling the energy distribution of the exposure laser, it is possible to obtain a master in which the cross-sectional shape of the recesses corresponding to the tracking grooves or address pits is asymmetrical. By using a stanbar made of resin, the flow of the resin during molding becomes smooth, and a molded article for an optical disk medium with few molding defects and excellent optical properties such as birefringence can be obtained. As a result, it has become possible to obtain a good reproduction signal.

[Brief explanation of the drawing]

Fig. 1(a) shows the energy distribution of the laser used when producing the conventional master disc, Fig. 1(b) shows the energy distribution of the laser used when producing the master disc of the present invention, and Fig. 2(a) shows the energy distribution of the laser used when producing the master disc of the present invention. FIG. 2(b) is a cross-sectional view of the pattern of the master disc of the present invention, FIGS. 3(a) to (C) are cross-sectional views of the pattern of another master disc of the present invention, and FIG. 5 is a cross-sectional view showing a resist pattern obtained in an example, and FIG. 6 is a cross-sectional view showing a conventional stanbar manufacturing process. It is. 1 glass plate 2: coupling agent 3: photoresist 4: metal film 5: plating layer 6: molded substrate 7: pinhole or slit

Claims (1)

[Scope of Claims] 1) In a master disc for manufacturing an optical disc, in which a photosensitive layer having a recess corresponding to a tracking groove or an address pit is provided on a substrate, a photosensitive layer having a recess corresponding to a tracking groove or an address pit; A master disc characterized in that its radial cross-sectional shape is asymmetrical. 2) the cross-sectional shape is substantially trapezoidal, and of the two parallel sides of the trapezoid, the shorter side forms the bottom of the recess;
2. The master disc according to claim 1, wherein the center of the short side is located on the inner peripheral side of the master disc from the center of the long side parallel to the short side. 3) The method for producing a master disc according to claim 1, comprising the steps of: after laminating the photosensitive layer on the substrate, the photosensitive layer is exposed to a high-density beam having a non-Gaussian cross-sectional energy distribution, and then developed. . 4) A molded article for an optical disc having a tracking groove or an address pit, wherein the cross-sectional shape of the tracking groove or address pit in the radial direction of the master is asymmetrical. 5) the cross-sectional shape is substantially trapezoidal, and of the two parallel sides of the trapezoid, the shorter side forms the bottom of the recess;
5. The molded article for an optical disk according to claim 4, wherein the center of the short side is located on the inner peripheral side of the molded article than the center of the long side parallel to the short side.