JPS62108248A - Fine pattern forming method - Google Patents

Abstract

PURPOSE:To form a fine pattern by coating a substrate with a thin film of an org. material having no sensitivity to high energy radiant rays such as X-rays or electron beams and by applying an X-ray resist to the thin film so as to reduce the effect of secondary electrons from the substrate on the X-ray resist. CONSTITUTION:A thin film 5 of an org. material having no sensitivity to radiant rays such as X-rays or electron beams is formed on a substrate 1 to be processed. An X-ray resist 2 is applied to the thin film 5, irradiated with soft X-rays 4 through an X-ray mask 3 and developed to form a fine X-ray resist pattern 2a. Polyimide resin, phenol resin or polyvinyl alcohol is used as the org. material. The effect of secondary electrons from the substrate 1 on the X-ray resist 2 is reduced and a fine pattern is easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a method of forming a fine resist pattern on a substrate to be processed using soft X-rays.

[Conventional technology]

FIG. 2 A-0 is a cross-sectional view showing the main stages of a conventional fine pattern forming method. First, a mask (3) is applied to an X-ray exposure resist (2) coated on a substrate (1). After irradiating soft X-rays (4) through the substrate (Fig. 2A) and developing to obtain a resist pattern (2a) (Fig. 2B), the substrate (1) is exposed using the resist pattern (2a) as a mask. was dry-etched. (Figure 2C). Alternatively, impurities were implanted into the substrate using the resist pattern as a mask.

For example, chlorinated polymethylstyrene (C!PMS) is used as a negative resist for X-rays (2) on an aluminum substrate (1).
) (MW 500,000, chlorination rate 92) was spin coded to a film thickness of 1.0 gm. Then, a film with a thickness of 1.5 mm was deposited on a composite substrate made of boronitride and boronitride film. gm's A
A PdLa beam (4,37
A) After irradiating (4) with 38mJ/(4m2), develop it,
A resist pattern (2a) was formed. Another 150W
The scum was removed using oxygen plasma, and the aluminum substrate (1) was dry-etched using act 4 gas using the resist pattern (2a) as a mask.
Spin code 00F and use the above mask (3).

After irradiating 250 m and 770 m2 using P (1 radiation source (4)), it was developed with an alkaline developer to form a resist pattern (2
a) was obtained.

[Problem that the invention seeks to solve]

X-rays have high transparency, and only 1a% is absorbed in the resist, so the X-rays that have passed through the resist are absorbed by the underlying substrate, which has a large absorption coefficient, and secondary electrons are generated from the substrate. The range of these secondary electrons is several hundred amperes, and the resist portion in contact with the substrate is exposed to light. Therefore, in conventional processes, these secondary electrons cause bridging and residue in negative resists, which impairs the resolution of the resist, and undercuts in positive resists.
There is a problem in that the pattern is easily peeled off, which ultimately hinders the formation of fine patterns.

This invention was made to solve the above-mentioned problems.In the case of negative resists, it is possible to eliminate bridging and the generation of residues, resulting in high resolution, and in the case of positive resists, it is possible to improve the adhesiveness with the substrate. It is an object of the present invention to provide a method for reliably forming fine patterns by increasing the

[Means for solving problems]

In the method for forming a fine pattern according to the present invention, an organic material film that is not sensitive to high-energy radiation such as X-rays and electron beams is thinly applied onto a substrate, and an X-ray resist is applied thereon. used.

[Effect]

In this invention, the thin organic material film coated on the substrate erases the secondary electrons generated from the substrate, and furthermore, the organic material film has a smaller X-ray absorption coefficient than the substrate and cannot generate secondary electrons. Therefore, the influence of secondary electrons from the substrate on the X-ray resist can be reduced.

〔Example〕

FIGS. 1A to 1D are cross-sectional views showing the main process steps of the method according to the present invention, in which the same reference numerals as in the conventional example shown in FIG. thickness 50
An organic material film (5) of 0 to 200 OA was formed, and an X-ray resist (2) was applied thereon, and as shown in FIG. After forming an X-ray resist pattern (2a) by etching, using this as a mask, the organic material film (5) is etched by oxygen plasma to form an organic material film pattern (5a) as shown in FIG. This is the same as the conventional example except that the overlapping resist pattern (2a) and organic material film pattern (5a) is used as a dry etching mask for the substrate (1). Explain.

Here, we will discuss submicron width A, which is essential for highly integrated devices.
I! An example of use in forming wiring is shown below.

Spin code diluted polyamic acid onto a sputtered aluminum substrate (1) and coat with N for 1 hour at a temperature of 2oO°C.
800A thick polyimide film (5) by baking in 2
was formed and then a CPMS resist (2
) was spin coated to a thickness of 1.0 μm, and a Pd source (4
) was used to form a submicron resist pattern (2a).The polyimide film (5) was further etched and removed using 200W 0□ plasma to form a polyimide film pattern (5a). 2a
) was cured with ultraviolet light, and then the aluminum substrate (1) was dry-etched to form submicron width A/wirings.

In addition, in recent years, MO8i□ or WSi□, which have low resistivity, have been used as gate materials for MOS devices.
These heavy metal compounds have particularly large X-ray absorption coefficients and tend to generate secondary electrons. Therefore, a polyimide film (5) with a thickness of 800A was formed on the substrate (1) on which sputtered MO8i□ was formed on the gate oxide film, and a 1.0μm thick polyimide film (5) was formed with l-5000P positive X-ray resist (2). After spin-coding, it was exposed to light using a Pd radiation source (4) and developed with an alkaline developer to form a resist pattern (2a) with a width of 0.5 pm. Then, polyimide and Maxi□ were dry-etched one after another to form a 0.5. An am width gate was formed.

In the above example, the case where a Pd source is used is shown.
Characteristic X-rays Rh(4,6oA) other than dLa rays, MO(
5.41A), 81(7,13A), Al(s, 3
4 people), 0u (13, 36A), etc. are similarly effective.

〔Effect of the invention〕

As described above, according to the present invention, since an organic material film that erases secondary electrons from the substrate is used, bridging and residue are eliminated in the case of a negative resist, and high resolution can be obtained. When a positive resist is used, there is no undercut at the bottom of the resist, and a fine pattern can be reliably obtained without pattern peeling.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the main process steps of a method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the main process steps of a conventional fine pattern forming method. In the figure, (1) is the substrate, (2) is the X-ray resist, (
2a) is an X-ray resist pattern, (3) is an X-ray mask,
(4) is a soft X-ray, and (5) is an organic material film.

Claims (2)

[Claims] (1) Form a thin organic material film that is not sensitive to radiation such as X-rays and electron beams on the substrate to be processed, apply an A method for forming a fine pattern, comprising a step of irradiating X-rays and performing a development process to obtain an X-ray resist pattern. (2) Formation of a fine pattern according to claim 1, characterized in that one member arbitrarily selected from a group consisting of polyimide resin, phenol resin, and polyvinyl alcohol is used as the organic material. Method.