JPS61222043A - Substrate for spin coating - Google Patents

Abstract

PURPOSE:To prevent the generation of a coating stain by forming a curved part having >=1mm radius of curvature to the edge of the inside circumferential surface of the central hole of a substrate and the surface of the substrate. CONSTITUTION:The curved part 3 having >=1mm radius of curvature is formed to the edge of the central hole 2 of the substrate 1 for spin coating and the surface of the substrate. The excess resist near the central part of the dropped resist is thereby quickly dropped through the central hole and the remaining of the resist at the edge is obviated. The splashing of the residual resist and the consequent generation of the coating stain are obviated and therefore a good disk having no deterioration of the SN ratio is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to the shape of a spin coating substrate for spin coating a resist.

[Technical background of the invention and its problems]

In recent years, information memory disks such as digital audio disks, video disks, and document file disks have been actively developed. These information memory discs are formed by a mastering process to create a master disc and a re-creation process to create a plastic disc. The former process involves polishing and cleaning a substrate for spin coating, such as a glass substrate, forming an adhesive layer, applying resist, baking, recording a signal with a laser, developing, forming an electrode for electroforming, and then forming a stamper by electroforming. The production is getting better.

The latter consists of a step of making a large number of copies of a plastic disk by a 2P molding method, an injection molding method, or the like using the stamper produced by the mastering process.

Among these steps, in the resist coating step, a resist is appropriately placed on the coating surface of a spin coating substrate made of a glass substrate or the like near the center hole of rotation, and spin coating (spin code) is performed. However, in the conventional substrate, the fourth
As shown in the simulated cross-sectional view in the figure, the boundary between the inner circumferential surface of the center hole and the surface of the base body is not smoothly connected. For this reason, the dripped and spread resist remains on the boundary between the inner circumferential surface of the center hole and the substrate surface during spin coating, and is scattered by centrifugal force during rotation and falls onto the semi-solidified resist coating surface. , spots with uneven resist film thickness (hereinafter referred to as coating spots) occur on the resist coating surface. If such coating stains occur, the length and depth of the pits will not be uniform when recording signals by forming bits, making it impossible to faithfully record input signals and reducing S/N. There were serious problems with information memory disks such as.

[Purpose of the invention]

The present invention has been made to solve these problems.
It is an object of the present invention to provide a spin coating substrate that can prevent coating stains that occur when conventionally coating resist with a spin cord.

[Summary of the invention]

The present invention provides a spin-coating base used for producing an information memory disk master master having a center hole that serves as the center of rotation when spin-coating a resist, the coating surface of the spin-coating base and the inner periphery of the center hole. It is characterized in that the surfaces are continuously connected with a radius of curvature of l1m11 or more. In other words, in the spin coating substrate according to the present invention, the surface of the substrate and the inner peripheral surface of the center hole are smoothly connected, so that the excess resist near the center of the dropped resist quickly passes through the center hole. and fall. Therefore, no excess resist remains in the vicinity of the boundary between the inner peripheral surface of the center hole and the surface of the substrate, and therefore, there is no possibility that this resist will scatter and cause coating stains as in the prior art. An example of its specific shape is shown in the simulated sectional views of FIGS. 1 and 2.

In both cases, the resist solution is dropped above the figure and applied by spinning. The concentration of the resist used here is l cp~1
0000 cp is used.

The radius of curvature connecting the base surface of the spin coating base according to the present invention and the inner peripheral surface of the center hole must be 1 mm or more. The reason for this becomes clear from the characteristic diagram shown in FIG.

The present inventors have an outer diameter of 350 m, a center hole diameter of 2°, and a thickness of 6 mm.
A base body such as the glass substrate described in (2) is prepared, and the base surface and the inner peripheral surface of the center hole are shaped as shown in the simulated cross-sectional view of Figure 1, and the radius of curvature is from 0.1 m to 10 mm. The occurrence of coating stains was investigated when various modifications were made and spin coating was performed on the coatings. Figure 3 shows the results. As can be seen from this figure, when the radius of curvature is small, many coating stains occur, and when the number of stains exceeds 1, #1 almost no stains occur. In addition, the upper limit of this radius of curvature may be appropriately determined depending on the thickness, size, and size of the recording image of the spin coating substrate used, and its shape can also be determined from the center hole from the substrate surface shown in Figure 1. In addition to the shape that connects to the inner circumferential surface, it may have a shape that smoothly connects the inner circumferential surface of the center hole from the surface of the base to the back surface of the base as shown in FIG. It is also possible to connect multiple values using different sizes.

〔Effect of the invention〕

In the spin coating substrate of the present invention, since the coating surface of the substrate and the inner circumferential surface of the center hole are connected with a radius of curvature of 1 m or more, there is no residual liquid coating agent for spin coating, resulting in the occurrence of coating stains. can be prevented. Ninthly, for example, by using the spin coating substrate of the present invention in the production of information memory disks, the resist can be coated uniformly and evenly, so that information memory disks can be manufactured with less S/N deterioration caused by conventional coating stains. Obtainable.

[Embodiments of the invention]

As a base for spin coating, outer diameter 350cm, center hole diameter 20m
A substrate made of soda glass with a thickness of 6 tsm was prepared. Then, the surface of the substrate and the inner circumferential surface of the center hole were processed into a continuous shape with a radius of curvature of 6 cm to obtain a substrate for spin coating as shown in FIG. 1 fc.

Five substrates of this shape were prepared, first ultrasonically cleaned with an aqueous surfactant solution, then purified water, and then dehydrated using isopropyl alcohol to form Freon TF (Mitsui Fluorochemical Co., Ltd.: trade name). It was dried. Next, an organic adhesive (hexamethyldisilazane) is applied to the surface of each substrate, and 7 Otoresist AZ-1350 (
Silapray Co., Ltd. (trade name) was spin-coated at a rotational speed of 300 rpm. The thickness of the formed resist film is approximately 9
It was 00A. Furthermore, these five resist-coated substrates were dried at 80° C. for 30 minutes, and then the number of coating stains on the coated surfaces was visually counted. As a result, no coating stains Ω could be observed on any of the five sheets. On the other hand, as a comparative example, a substrate having the shape shown in FIG. 4 in which the coated surface of the substrate and the inner peripheral surface of the center hole are not connected by a curved surface having a predetermined curvature was used. ,
Five sheets of the same size as the example of the present invention were prepared. Then, a resist was applied to this in the same process as described above.

After drying at 80°C for 30 minutes in the same manner as in the examples of the present invention,
When the number of coating stains was counted by visual inspection, 5 to 10 coating stains were observed on each coated surface.

In addition, when similar signals were recorded and reproduced on an optical disk manufactured using the spin coating substrate according to the present invention and an optical disk manufactured using a conventional substrate, it was found that the conventional photon film was not the same as that of the present invention. Significant S/N deterioration was observed compared to the optical disc according to the above.

[Brief explanation of drawings]

1 and 2 are simulated cross-sectional views showing an example of a spin coating substrate according to the present invention, and FIG. 3 shows the radius of curvature of the surface connecting the coating surface of the substrate and the inner peripheral surface of the center hole. 9 is a characteristic diagram showing the relationship with the number of coating stains. FIG. 4 is a simulated sectional view showing the shape of a conventional spin coating substrate. 1.4 ・・・・・・ Substrate 2.5 ・・・・・・ Center hole 3 ・・・・・・ Partial representative patent attorney with curvature Kensuke Chika (and 1 other person) Figure 2

Claims (2)

[Claims] (1) In a spin coating substrate used for producing a master master of an information memory disk, which has a center hole that serves as the center of rotation when applying resist by spin coating, the spin coating is cut along a plane that includes the center line of the center hole. The edge of the cross-section of the base for spin coating, which corresponds to the inner circumferential surface of the center hole, and the subsequent edge of the base for spin coating, which corresponds to the coating surface, are continuous with a radius of curvature of 1 mm or more. Substrate for spin coating. (2) The spin coating substrate according to claim 1, which is made of glass.