JPH049954A - Development method by wet process - Google Patents

Abstract

PURPOSE:To execute efficient development while preventing the film decreasing in nonexposed parts by exposing a resist film with prescribed patterns, then subjecting the resist film continuously to two stages of the development by using 1st and 2nd developers. CONSTITUTION:The positive type photoresist film 2 is first formed on a prescribed substrate 1. This film 2 is then irradiated with a laser 3 subjected to light modulation. The 1st developer 4 is thereafter brought into contact with the surface of the film 2. The surface of the film 2 is thereafter rinsed with pure water and the 2nd developer 5 is brought into contact threwith. The film is then rinsed with pure water. The developer 4 in this constitution is low in concn. and, therefore, the surface of the exposed parts remains slightly but the compd. contg. the photosensitive groups condenses in the nonexposed parts and generate the azo compd. which is hardly liable to generate the shape roughening and film decreasing. The exposed parts are dissolved and removed in this state by the developer 5 of the high concn. The development is efficiently executed while the film decreasing in the nonexposed parts is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wet developing method used for manufacturing optical discs, etc.

(Conventional technology) IC manufacturing technology is also applied to the production of optical discs.
One such method is to form groups or bits on a positive resist film using a wet development method.

In other words, in the conventional wet development method, a resist film containing photosensitive groups is irradiated with laser light in a predetermined pattern, and the exposed areas are dissolved in an alkaline solution (developer) and removed. The exposed areas also dissolve to the point where they cannot be ignored.
The so-called film thinning promotes the taper of the developed pattern.

Therefore, a method for alkali treatment of a resist is known, which is disclosed in Japanese Patent Application Laid-Open No. 59-84426.

In this method, as shown in FIG. 3(A), a resist film 101 is formed on a substrate 100 such as a glass plate, and then, as shown in FIG. After being exposed to the strong alkaline solution 102, it was washed with water and dried, and then exposed to light as shown in FIG. 3(C), and then exposed to the strong alkaline solution 102 again as shown in FIG. 3(D). This is a method of forming the developed pattern 103 shown in E), in which the surface of the resist film before exposure is exposed to a strong alkaline solution to reduce film loss in non-exposed areas and prevent the developed pattern from tapering.

(Problems to be Solved by the Invention) In the alkali treatment method described above, the surface of the resist film is exposed to a strong alkali, then rinsed with pure water, and the pure water is scattered by blowing nitrogen gas or using a spinner. However, it cannot be completely dispersed and some parts remain. The areas where moisture remains become spots and dropouts occur during exposure, and the refractive index changes in areas where moisture remains, preventing light from penetrating into the resist film, causing the bit shape to collapse as shown in Figure 4. It ends up.

In order to completely dry the water used for rinsing in order to solve this problem, it is necessary to perform soft baking or air drying, and the former requires an increased number of steps, and the latter takes time.

(Means for Solving the Problems) In order to solve the above problems, the present invention exposes a positive photoresist film formed on a substrate such as a glass disk to light in a predetermined pattern, and then exposes a first and second photoresist film to light. Two stages of development were carried out continuously using a developer.

(Function) When the resist film surface after exposure is brought into contact with the first developer, the first developer has a low concentration, so the surface of the exposed area is slightly dissolved, but the surface of the unexposed area is free of photosensitive groups. The contained compounds condense to form an azo compound that is less likely to cause shape roughness or film thinning. In this state, the exposed portion is dissolved and removed using a high-concentration second developer.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram explaining the method of the present invention step by step. In the present invention, first, as shown in FIG. 1(A), a positive resist solution is applied onto a substrate 1 such as a glass disk using a spinner or the like. A resist film 2 is obtained by uniformly applying and drying this. Here, the resist is mainly composed of a novolak resin and contains an O-naphthoquinonediazide F group as a photosensitive group.

Next, as shown in FIG. 1B, the resist film 2 is irradiated with optically modulated laser light 3 in a spiral or concentric pattern. Then, the exposed portion 2a of the resist film 2 becomes a carboxylic acid soluble in an alkaline solution (developer).

Thereafter, as shown in FIG. 1(C), the first developer 4 is brought into contact with the surface of the resist film 2. As the first developing solution, a 0.3% inorganic alkali aqueous solution (eg, NaOH aqueous solution) is used. The developing time is set to such an extent that the surface of the exposed portion 2a is slightly dissolved, specifically about 60 seconds. Further, in the non-exposed portion 2b, a compound containing a photosensitive group is condensed to form an azo compound.

After this, the surface of the resist film 2 is rinsed with pure water as shown in Figure 1 (
The second developer 5 is brought into contact as shown in D). Second
As the developer 5, an inorganic alkaline aqueous solution similar to the first developer is used, and its concentration is about 10%, which is higher than that of the first developer. The development time is set until the exposed portion 2a is completely dissolved, specifically about 4
Set to 0 seconds.

Thereafter, by rinsing the surface of the resist film 2 with pure water, pits 6 or groups are formed in a predetermined pattern as shown in FIG. 1(E).

(Effects) Figure 2 is a graph showing the relationship between development time (seconds) and film reduction amount (μm). The resist film is exposed to light in a predetermined pattern, and then a low-concentration first developer is used to alter the surface of the unexposed areas, and then a high-concentration second developer is used to dissolve the exposed areas. Therefore, development can be carried out efficiently while preventing film loss in non-exposed areas.

[Brief explanation of the drawing]

Figures 1 (A) to (E) are diagrams showing the method of the present invention in the order of steps, Figure 2 is a graph showing the relationship between development time (seconds) and film reduction amount (μm), and Figures 3 (A) to (E) is a diagram showing the conventional method in the order of steps, and FIG. 4 is an enlarged view of a bit formed by the conventional method. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Resist film, 2a...Exposed part, 2b...Non-exposed part, 3...Laser light, 4...
- First developer, 5... Second developer. Patent applicant Japan Victor Co., Ltd. Figure 5! , image time (Le V) Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] A positive photoresist film is formed on a substrate such as a glass disk, this photoresist film is exposed to light in a predetermined pattern, and then the surface of the photoresist film is coated with a first developer until the exposed portion of the surface is slightly dissolved. contact with
A wet developing method characterized in that the surface of the photoresist film is then washed with water and further the exposed portion of the photoresist film is dissolved with a second developer.