JP2773565B2 - Pit forming method 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 the manufacture of optical disks, and more particularly, to a technique for reducing the pit shape in high density optical disks.

[0002]

2. Description of the Related Art Conventionally, as recording densities of CD-ROM discs have increased, there has been a demand for shorter recording pits. For this purpose, research on reducing the beam spot during master master exposure has been actively conducted, and the beam diameter is reduced by using a method of reducing the beam diameter by making the exposure beam a single wavelength or by using a super-resolution phenomenon. CEL that reduces the beam diameter by using an apparently smaller method or a material contrast enhancer (CEM) that transmits light only in the central portion where the intensity of the exposure beam spot is high
And a method of forming pits smaller than pits to be formed originally by extending the development time using a negative resist.

[0003]

The diameter of a pit formed by such a conventional method described above is at most 0.38 μm.
In order to increase the density of the optical disk, the pit diameter must be further reduced.

[0004] An object of the present invention is to provide a pit forming method which eliminates the above-mentioned disadvantages by exposing a negative resist by the CEL method and lengthening the developing time to form short pits which could not be obtained conventionally. It is in.

[0005]

The pit forming method of the present invention uses a master having a structure in which a negative type photoresist is coated on a glass substrate, and a contrast enhancer is coated thereon, and the master is beam-formed. narrowing the region to be exposed to post-exposure by exposing spot, Seo said negative photoresist from the exception takes the contrast enhancing agent
The development time of the negative photoresist after the bake is made two to three times longer than the optimal development time for developing the negative resist alone, thereby forming smaller optical disk pits.

[0006]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an exposure master just before exposure using the pit forming method of one embodiment of the present invention, and FIG. 2 is a barrier coating agent (BC) 12 and a contrast enhancer (CEM) of the exposure master shown in FIG. 13) is a diagram illustrating a method of removing the .13.

In FIG. 1, an exposure master is a glass substrate 1
Negative resist on AZ0 (AZ5200-E from Hoechst Japan)
11 is applied by a spinner to about 700 μm. After the negative resist 11 is sufficiently dried, the barrier coating agent (BC) 1
2 is coated on the order of 1000 μm and a contrast enhancer (CEM) 13 is applied on the order of 3000 μm. After exposing this exposure master to pits using an exposure apparatus, FIG.
As shown in FIG. 5, a paddle 20 is filled with pure water 21, and an exposed master 22 is immersed in pure water 21 in the pure water 21 to form a barrier coating agent (BC) 12 and a contrast enhancer (CE).
M) 13 is removed. Next, the negative resist left on the substrate is soft-baked at 80 ° C. to 90 ° C. for 5 to 10 minutes, so that the exposed portions are linked and become insoluble in the developing solution. Thereafter, a negative resist is dip-developed in a paddle filled with a developer (AZ300MIF from Hoechst Japan) to form pits.

[0009]

As described above, according to the pit forming method of the present invention, by providing a contrast enhancer on a negative resist, light is transmitted only through the central portion of the exposure beam spot where the intensity is high. Has the same effect as that obtained by exposure with a beam having a small beam diameter.

Further, by extending the developing time of the negative resist, there is an effect that a smaller pit of about 0.27 μm can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an exposure master immediately before exposure using a pit forming method according to an embodiment of the present invention.

FIG. 2 shows a barrier coating agent (BC) 12 of the exposure master shown in FIG.
FIG. 3 is a diagram showing a method of removing a contrast enhancer (CEM) 13.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Glass substrate 11 Negative resist 12 Barrier coating agent 13 Contrast enhancer 20 Paddle 21 Pure water 22 Exposed master

Continued on the front page (72) Inventor Kazuhiko Yamada 5-7-1 Shiba, Minato-ku, Tokyo Inside the NEC Corporation (72) Inventor Hitoshi Yokota 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation In-company (56) References JP-A-3-223760 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G11B 7/26 501

Claims (1)

(57) [Claims] An area exposed after exposure by using a master having a structure in which a negative photoresist is coated on a glass substrate and a contrast enhancer is coated thereon, and the master is exposed to a beam spot. the narrow, the negative Fotore from excluding take the contrast enhancing agent
The pits of an optical disk, wherein the development time of the negative photoresist after the soft baking of the dist is made two to three times longer than the optimal development time when developing the negative resist alone to form smaller pits. Forming method.