JPH0334055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for forming fine resist patterns in the production of semiconductors, magnetic bubble elements, and optical application parts.

(Prior art) In recent years, there has been an extremely high demand for higher integration of semiconductor integrated circuits, etc., and in line with this, in the field of lithography, conventional light (particularly ultraviolet light) has been replaced with electron beams, X-rays, far ultraviolet light, etc. Light sources with short wavelengths have been used.

In particular, lithography using deep ultraviolet rays is an extension of conventional photolithography, but it can easily perform submicron transfer, and there are great expectations for future microfabrication technology.

By the way, the resist material used for such microfabrication is required to have high sensitivity in the deep ultraviolet region and particularly good resolution, heat resistance, and dry etching resistance, but polymethyl methacrylate (hereinafter abbreviated as PMMA) is It is well known as a resist for far ultraviolet rays, and by performing close exposure using a conformable mask,
It exhibits high resolution of 0.2 μm or less. But this
PMMA has low sensitivity, and it cannot be said that its dry etching resistance is sufficient.

In addition, methacrylic acid ester polymers and methacrylic acid ester copolymers are known as other deep ultraviolet ray resists, but these also do not have sufficient dry etching resistance, like the above-mentioned PMMA.

That is, a resist material that is highly sensitive to the above-mentioned deep ultraviolet rays, has good resolution, and has high dry etching resistance and heat resistance has not been developed, and there is a need to establish a method for forming such a resist pattern. That is the reality.

(Purpose of the Invention) As a result of repeated research to solve this problem and meet the above requirements, the present inventors irradiated a resist film made of naphthoquinonediazide sulfonic acid ester of novolac resin with far ultraviolet rays and heated it at a predetermined temperature before development. The present invention was achieved by discovering that by heating, a resist pattern having excellent dry etching resistance and heat resistance as described above and good resolution can be formed with high sensitivity.

(Structure of the Invention) That is, the present invention irradiates a resist film of naphthoquinonediazide sulfonic acid ester of a novolac resin formed on a substrate with deep ultraviolet rays of 180 to 300 nm, heats it at a temperature of 50 to 120°C, and then irradiates it with isoamyl acetate. This is a negative resist pattern forming method characterized by developing with a developer containing as a main component.

In this invention, a resist using a naphthoquinone diazide sulfonic acid ester of the above-mentioned novolak resin, specifically a naphthoquinone 1,2-diazide-5-
The reason why the sensitivity of sulfonic acid ester (hereinafter abbreviated as LMR) increases when it is heated after irradiation with far ultraviolet rays is considered to be as follows. That is, LMR
The quinone diazide group undergoes a structural change when exposed to far ultraviolet rays, making it insoluble in isoamyl acetate, and a negative resist pattern can be formed.

Moreover, the reason why high sensitivity is shown by heating is that the reaction does not proceed 100% to the final product (insoluble in isoamyl acetate) by irradiation with far ultraviolet rays and remains as an intermediate substance (insoluble in amyl acetate). It is thought that the transition from intermediate substances to final products occurs only after

Also, since LMR has large absorption in the far ultraviolet region,
Light cannot reach near the substrate. That is, the irradiated area consists of an upper part that is a reactive layer and a lower part that is an unreacted layer, and the developer easily penetrates between them during development. However, if heating is performed after development, the reaction layer and the unreacted layer will have better adhesion, and pattern defects due to seepage will be eliminated.

The lower limit of such temperature conditions is about 50°C, and the reason why patterning is not possible at temperatures exceeding the upper limit, such as 130°C, is because thermal crosslinking occurs due to the decomposition of the quinonediazide groups at temperatures above 130°C, making the LMR insolubilized in the solvent.

That is, in the present invention, heating after exposure is 50 to 120°C.
is the range that is effective for increasing sensitivity, especially 80 to 110
°C is most desirable.

(Example) The present invention will be specifically described below with reference to Examples.

Example 1 Dissolving LMR in methylcellosolve acetate,
After passing through a 0.2 μm filter, a 0.6 μm film was deposited on the Si substrate.
It was applied thickly. After baking at 60° C. for 30 minutes, exposure was performed for 3 seconds, 5 seconds, and 10 seconds using a contact method using a 500 W Xe-Hg lamp.

After heating at 100℃ for 30 minutes, it was developed with isoamyl acetate (added with 0.1% water) and the result was 0.5μ.
The line and space of m is the above exposure amount of 3 seconds, 5
Both seconds and 10 seconds were well resolved. The cross-sectional shape of the obtained resist was an overhanging shape.

Comparative Example 1 When exposure was performed in the same manner as in Example 1 and immediately developed with the same developer, a pattern could be formed in the case of 10 seconds, but no pattern could be formed in the case of 3 seconds and 5 seconds.

In addition, some penetration of the developer between the reacted and unreacted resist layers was observed.

Example 2 After exposure was carried out in the same manner as in Example 1, the film was heated at 50°C and 130°C for 30 minutes and developed in the same manner. 50℃
In the case of heating, resolution could be achieved for 5 and 10 seconds, but resolution was not sufficient for 3 seconds. Further, at 130°C, the pattern was not dissolved in the developer at all and no pattern could be obtained.

(Effects of the Invention) As is clear from the above description, the present invention is capable of forming a resist pattern with high sensitivity using deep ultraviolet rays and having excellent dry etching resistance and heat resistance as well as excellent resolution. As mentioned above, the cross-sectional shape of the pattern is good, with almost an overhang, and lift-off of metals such as aluminum and gold is easy. It has great industrial utility value as it has remarkable effects.

Claims (1)

[Claims] 1. A resist film of naphthoquinonediazide sulfonic acid ester of novolac resin formed on a substrate is irradiated with deep ultraviolet rays of 180 to 300 nm, and
A negative resist pattern forming method characterized by heating at a temperature of 120°C and then developing with a developer containing isoamyl acetate as a main component.