JPH0249233A - Production of optical disk substrate - Google Patents

Abstract

PURPOSE:To form the substrate which is extremely little burred by circumferentially providing a spacer near the outermost periphery of a stamper and dropping a radiation curing resin thereto, then placing the glass substrate on the spacer, pressurizing the substrate, removing the spacer and further, pressurizing the substrate. CONSTITUTION:The spacer 4 is circumferentially provided near the outermost periphery of the stamper 1 and while the stamper 4 is rotated, the radiation curing resin 3 is dropped to the suitable position on the stamper. The substrate 2 is then lowered and is brought into contact with the spacer 4 and the resin 3. Since a non-packed region is generated only by the weight of the substrate 2, another substrate or the like is placed on the substrate 2 and is pressurized to uniformly pack the resin. The resin 3 is packed uniformly near to the outermost circumference by the weight of the substrate 2 when the spacer 4 is removed thereafter. The burrs formed by bleeding to the outermost periphery of the glass substrate is substantially obviated in this way.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing an optical disc substrate, the present invention relates to a method for manufacturing an optical disc substrate in which the radiation-curable resin does not protrude and form a gap when the radiation-curable resin is filled between a standby bar and a glass substrate. For the purpose of this, the process includes the step of providing a spacer around the outermost circumference of the stamper, and placing a glass substrate on the radiation-curable resin and the spacer after hanging the radiation-curable resin in an annular shape on the stamper. a step of applying pressure to the glass substrate to spread the radiation-curing resin so as to cover at least almost the entire region in which the stamper-like group pattern is engraved (group region); and a step of removing the spacer and removing the spacer. The method includes a step of pushing and spreading the radiation-cured resin to the vicinity of the outermost circumference of the glass substrate by the weight of the glass substrate.

[Industrial Field of Application] The present invention relates to a method of manufacturing an optical disc substrate, and more specifically, to a method of manufacturing an optical disc substrate as a writable storage medium.

[Prior Art] Conventionally, as a method of manufacturing an optical disk substrate, there is a method of transferring a fine group pattern on a stamper, that is, a photopolymer method (hereinafter referred to as 2P method).

FIGS. 3(a) to 3(d) are process explanatory diagrams of group pattern transfer by the 2P method according to a conventional example.

In the figure, reference numeral 1 denotes a stamper on which track 2 sector identification data and a group pattern consisting of approximately tens of thousands of track guide grooves are recorded by concavities and convexities.

2 is a substrate such as glass, 3 is a radiation curing resin for copying the group pattern on the stamper, and 6 is an ultraviolet ray which is a type of radiation.

Hereinafter, the manufacturing process of an optical disk substrate according to a conventional example will be described with reference to the drawings.

First, while rotating stamper 1 at low speed,
The radiation-cured resin is suspended above and supplied in an annular manner (third
Figure (a)).

Next, the glass substrate 2 is lowered and brought into contact with the radiation-cured resin 3, and then pressed to gradually spread the radiation-cured resin to form a group area of the stamper 1 (a circle of r=55 mm and a circle of r=55 mm).
Fill the entire area (area surrounded by a 95 mm circle). Thereafter, the radiation curing resin was cured by irradiating ultraviolet rays 6 from the substrate side (FIG. 3(b)), and the glass substrate 2 was peeled off from the stamper 1 to create an optical disk substrate having a group pattern. (Figure 3(c)
).

After this, a thin film of a recording material (for example, TbFeCo metal sandwiched with a 'rb-5iOz protective film) is formed on the radiation-cured resin onto which the group pattern has been transferred, and the two optical discs are bonded together on the entire surface with an adhesive. As a result, a rewritable optical disc is completed.

[Problems to be Solved by the Invention] However, in the conventional 2P method, when filling the space between the stamper 1 and the glass substrate 2 with radiation-curable resin, the group pattern on the stamper is carved between a radius of 55 mm and a radius of 95 mm. Therefore, if you try to completely fill this area (group area), the radiation-cured resin may protrude beyond the outermost circumference (radius 100 mm) of the substrate, forming a gap (see Figure 3). C)) When the Paris hardens, small pieces of Paris tend to separate and remain attached to the stamper or the hardened radiation-cured resin of the glass substrate after one separation.

If the pads remain on the stamper side, the next time the group pattern is transferred to another substrate, the substrate will be placed on top of the pads.
There is a problem that 2P will not spread. On the other hand, if it remains on the hardened radiation-cured resin on the glass substrate side, when trying to form a thin film of the recording material in the next step, the part to which the paris has adhered may not be able to be formed. There is a problem in that it causes data writing or reading errors, and the yield of non-defective products deteriorates.

The present invention was created in view of such conventional problems, and it is an object of the present invention to provide a method for manufacturing an optical disk substrate that can prevent the occurrence of flakes caused by the radiation-cured resin protruding from between the substrate and the stamper. purpose.

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of an optical disc substrate manufacturing process according to an embodiment of the present invention.

In the figure, 1 is a stamper on which track/sector identification data and a group pattern consisting of about tens of thousands of track guide grooves are recorded by unevenness, 2 is a substrate such as glass, and 3 is radiation hardening that copies the group pattern on the stamper. The resin 4 is a spacer provided around the outermost circumference of the stamper, and usually three spacers are used, but more than this may be used.

[Function] In the method for manufacturing an optical disk substrate of the present invention, a spacer 4 is provided around the outermost circumference of the stamper 1, and the radiation-cured resin 3 is suspended at an appropriate position on the stamper while rotating the stamper. supply

Next, the substrate 2 is lowered to contact the spacers 4 and the radiation-cured resin 3.

At this time, because the weight of the substrate alone causes unfilled areas with the radiation-cured resin, for example, another substrate is placed on top of the substrate and pressure is applied to uniformly fill the entire surface.

By the way, the group pattern on the stamper has a radius of 55m.
m to a radius of 95 mm, and this area (group area) needs to be completely filled. Pay attention to this when applying pressure.

After that, when the spacer 4 is removed, the radiation curing resin 3 is transferred to the outermost circumference of the glass substrate (radius 10
0mm), that is, from a radius of 95mm to a radius of 100mm
It becomes possible to fill uniformly and approximately concentrically up to a distance of 1 mm. For this reason, unlike the conventional method, there are almost no holes formed protruding from the outermost circumference of the glass substrate.

[Example] FIGS. 2(a) to 2(d) are explanatory diagrams of an optical disc substrate manufacturing process according to an example of the present invention.

In the figure, 1 is a stamper on which a group pattern consisting of track/sector identification data and about five track guide grooves is recorded by unevenness, 2 is a substrate such as glass, and 3 is radiation hardening that copies the group pattern on the stamper. 4 is a spacer provided around the outermost circumference of the stamper, and 5 is an unfilled area of the radiation-cured resin that is formed when no pressure means is used on the substrate.

Below, Figures 1 (a) to (b) and Figures 2 (a) to (d)
The manufacturing process of the optical disc substrate will be explained with reference to .

First, spacers 4 with a thickness of 35 pm are placed around the outermost circumference of the stamper 1 at 3 locations), and the stamper is rotated at low speed, and 0.8 g
A radiation-curable resin 3 (for example, an acrylic acid ester having a viscosity of 1 poise) is fed in a circular manner (FIG. 2(a)).

Next, the glass substrate 2 with a diameter of 200 mm is lowered and brought into contact with the spacer 4. At this time, since the radiation-cured resin 3 was expanded only by the weight of the substrate 2, an unfilled region 5 of the radiation-cured resin was created (FIG. 2(b)).

By the way, the group pattern on the stamper has a radius of 55m.
It is carved between m and radius 95mm.

This area (group area) must be completely filled. Therefore, for example, place another board or the like and apply sufficient pressure to spread the radiation-cured resin 3 as a whole (see Figure 2).
(C)), at this time, the substrate 2 is
Since the lower surface of the circumferential end of the stamper 1 is separated from the upper surface of the stamper 1 by a certain distance, the radiation-cured resin 3 does not reach the outside of the substrate 2.

Note that when the radiation curing resin 3 reaches and contacts the spacer 4, it is desirable that it does not reach the spacer 4 as well, as this may cause cracks. This is easily possible by appropriately selecting and adjusting.

Thereafter, the spacer 4 is removed, and the radiation-cured resin is pushed and spread by the weight of the glass substrate 2. As a result, the radiation curing resin is applied to the outermost circumference (radius 100 mm) of the glass substrate 2.
Filling is uniform and almost concentric to the vicinity.

Thereafter, the radiation curing resin 3 is cured by irradiation with ultraviolet rays, and the glass substrate 2 is peeled off from the stamper 1, thereby producing an optical disk substrate having a group pattern.

In fact, in the substrate 2 prepared in this manner, there was no protrusion of the radiation-cured resin, and no particles were observed at all.

[Effects of the Invention] As explained above, according to the present invention, by filling the radiation curable resin uniformly and almost concentrically to the vicinity of the outermost circumference of the substrate, the radiation curable resin does not protrude. It is possible to create a substrate with extremely few particles.

As a result, if the Paris remains on the stamper, when the group pattern is transferred to another substrate in the next step, the substrate may be placed on top of the Paris, preventing the 2P from spreading, or the Paris may remain on the glass substrate. If the particles remain on the cured radiation resin, when trying to form a thin film of recording material in the next step, it may become impossible to form a recording thin film on the areas where the particles have adhered. Since the problem can be solved, it greatly contributes to improving the yield of non-defective optical disk substrates.

[Brief explanation of the drawing]

1 is an explanatory diagram of the principle of an optical disk substrate manufacturing process according to an embodiment of the present invention; FIG. 2 is an explanatory diagram of an optical disc substrate manufacturing process according to an embodiment of the present invention; FIG. 3 is a conventional example FIG. 2 is an explanatory diagram of an optical disc substrate manufacturing process using the zP method. (Explanation of codes) 1... Stamper, ? ...Glass substrate, 3. Radiation curable resin, 4. Spacer, 5. Radiation curable resin unfilled area, 6. Ultraviolet rays, 7. Paris.

Claims (1)

[Claims] A step of providing a spacer around the outermost circumference of the stamper, and placing a glass substrate on the radiation-curable resin and the spacer after hanging the radiation-curable resin in an annular shape on the stamper. a step of applying pressure to the glass substrate to spread the radiation-curable resin so as to cover at least almost the entire region in which the stamper-like group pattern is engraved (group region); and a step of removing the spacer. . A method of manufacturing an optical disk substrate, comprising the steps of: pushing and spreading the radiation-cured resin to the vicinity of the outermost circumference of the glass substrate by the weight of the glass substrate.