JPH02256055A - Resist material and pattern forming method using same - Google Patents

Abstract

PURPOSE:To obtain a resist having superior dry etching resistance, high sensitivity and resolution fit for practical use and to form a fine pattern by using a specified copolymer as a resist material for exposure. CONSTITUTION:A copolymer represented by formula I is used as a positive resist material for exposure with radiation. This resist material is applied to a substrate and irradiated with high energy radiation to form a mask and the substrate is dry-etched through the mask to form a pattern. In the formula I, X is phenyl or a deriv. thereof and Y is an electron withdrawing group. The copolymer represented by the formula I contains arom. rings having superior dry etching resistance in the structure and the principal chain is liable to break because the acrylonitrile skeleton has the electron withdrawing group substd. at the alpha-position. Accordingly, a resist having superior dry etching resistance, high sensitivity and resolution fit for practical use are obtd. and a fine pattern is formed by using the resist.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a radiation-sensitive positive resist used for patterning in the manufacture of semiconductor integrated circuits and a pattern forming method using this resist, which has excellent dry etching resistance and is suitable for practical use. For the purpose of providing a resist with high sensitivity and resolution as well as a method of forming @fine patterns using this resist, we have developed a method for using a copolymer represented by the following general formula as a resist material for exposure. Configure.

However, X is a phenyl group or a derivative thereof, and Y is an electron-withdrawing group.

[Industrial application field]

The present invention relates to a radiation-sensitive resist used for patterning in the manufacture of semiconductor integrated circuits, and a pattern forming method using this resist.

In recent years, in the manufacture of semiconductor integrated circuits, as the demand for higher density and higher integration of elements has increased, efforts have been made to establish ultra-thin circuit pattern technology. In line with this trend, methods have been developed in lithography for forming patterns using high-energy radiation such as deep ultraviolet rays with short wavelengths, X-rays, and electron beams instead of conventional ultraviolet rays. Accordingly, it is essential to develop high-performance resist materials that are sensitive to these high-energy radiations.

When manufacturing semiconductor integrated circuits using high-energy radiation, a method is used in which a resist material is applied onto a substrate, then radiation is irradiated and developed, resulting in a fine pattern that is used as a mask to etch the substrate. .

In such manufacturing processes, resists are required to have high sensitivity and high resolution so that patterns in the submicron region can be obtained. Furthermore, regarding the etching process, the wet etching method, which causes large side etching, has been replaced by a dry etching method using reactive sputtering or the like. For this reason, resists are required to have further dry etching resistance.

[Conventional technology] Conventionally, in radiation-sensitive positive resists,
Many polymers have been developed that obtain positive patterns by lowering the molecular weight by irradiating the polymer with radiation and utilizing the solubility difference due to the difference in molecular weight, but none of them satisfy all of the above performance requirements. For example, PMMA (methyl methacrylate polymer) is a resist material with excellent resolution, but its sensitivity (Dg') to electron beams is 50 to 100.
Since it is about μC/cm2, it cannot be said to have high sensitivity for practical use.
Also, the dry etching resistance is not sufficient. EBR-9 (trade name of Takushiku Co., Ltd.), which uses a polymer with the following general formula, has a higher decomposition efficiency for high-energy radiation than PMMA, and therefore has high sensitivity, but has significantly poor dry etching resistance. Become.

Me C-0-6, 1. . , 3 On the other hand, a material having an aromatic ring in the unit structure as shown in the general formula below has excellent dry etching resistance, but has poor sensitivity to radiation, resulting in extremely low sensitivity.

[Means for Solving the Problems] The present invention utilizes the fact that the following polymer has a practically high sensitivity to radiation and has excellent dry etching resistance.

[Problems to be Solved by the Invention] Therefore, conventionally, it has not been possible to obtain a material with excellent dry etching resistance and high sensitivity for practical use, and there has been no radiation-sensitive resist that satisfies the above-mentioned performance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a resist that has excellent dry etching resistance, high sensitivity and resolution suitable for practical use, and a method for forming fine patterns using this resist. .

Y is an electron-withdrawing group.

That is, the first aspect of the present invention is a positive resist material for radiation exposure characterized by using a copolymer represented by the above general formula, and the second aspect of the present invention is a positive resist material using a copolymer represented by the above general formula. This pattern forming method is characterized by applying the used positive resist onto a substrate and dry etching the substrate using a mask formed by irradiating high-energy radiation.

[Function] The copolymer shown in the above-mentioned maximum used in the present invention has excellent dry etching resistance because it contains an aromatic ring in its structure, and on the other hand, the acrylotrile skeleton is substituted with an electron-withdrawing group at the α position. Therefore, the polymer main chain is easily broken, resulting in high fidelity. Therefore, this copolymer becomes a positive resist with excellent dry etching resistance and practical sensitivity. As a derivative of phenyl group, (however, X
-H1-R1-OR (R is alkyl), -0H), etc. can be used.

Hereinafter, the present invention will be explained in more detail with reference to Examples.9 [Example] Example 1 α-methylstyrene and α-chloroacrylonitrile
:1 and radical polymerization with AIBN was performed using 1.4-dioxane as a solvent to obtain a copolymer with Mw=40,001, dispersity 1.61, and composition ratio 1:1. After making this polymer into a cyclohexanone solution, Si wafe
Spin code to a thickness of 1.0 μm on the
Becking was performed for a minute. As a result of exposing the obtained resist film to an electron beam with an acceleration voltage of 20 KV while changing the exposure amount, D m. A sensitivity of = 20 t-t C/cm2 was obtained (see Figure 1). The slope (γ) of the sensitivity curve in Figure 1 was 4.0.9 This resist film had a slope of 0.37.
5 μm line and space was resolved. Next CF 4
When reactive sputter etching was performed using + CHF 3 mixed gas and the film loss of the resist film was investigated, the results shown in Table 1 were obtained, and the etching resistance was equivalent to that of 0FPR-800, which is a positive type photoresist. I understand.

(Comparative Example 1) PMMA, which is a typical positive resist, was used in Example 1.
The results of processing in the same manner as above are shown in FIG. 1, Tables 1 and 2. Compared to these results, the resist of the present invention has approximately twice the sensitivity and etching resistance.
The resolution powers were comparable.

(Example 2) In Example 1, if the charging ratio during synthesis was set to 7:3, M
A polymer having w=70,000, a dispersity of 1.8, and a composition ratio of 1:1 was obtained, showing the same performance as Example 1.

(Comparative Example 2) In Example 2, radical polymerization was performed using methacrylonitrile in which the α-position is an electron-donating group instead of α-chloroacrylonitrile. As a result, Mw = 60,000, dispersity 1.7, composition ratio. A 1:1 copolymer was obtained. After applying this and exposing it to light,
When developed using a mixed solvent of toluene/ethylbenzene-1/1, D g' = 2000 μC/
The sensitivity was low at cm2.

The development conditions in the above examples and comparative examples were butyl cellosolve acetate = 10/1.90 sec.

The radiation-sensitive positive resist shown in Table 1 (hereinafter blank) can be obtained and greatly contributes to the formation of ultra-fine patterns.

[Brief explanation of drawings]

FIG. 1 is a sensitivity curve of a copolymer of α-methylstyrene and α-chloroacrylonitrile with a composition ratio of 1:1.

Claims (1)

[Claims] 1. A resist material for radiation exposure characterized by using a copolymer represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, X is a phenyl group or its derivative, and Y is an electron-withdrawing group. 2. A pattern forming method characterized by applying a resist using a copolymer represented by the following general formula to a substrate and dry etching the substrate using a mask formed by irradiating high-energy radiation. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, X is a phenyl group or its derivative, and Y is an electron-withdrawing group.