JPH02103545A - Positive type photoresist material and pattern forming method - Google Patents

Abstract

PURPOSE:To improve the selection ratio with a lower flattened layer while having practicable sensitivity by using a positive type resist material consisting of a copolymer of a styrene deriv. subjected to nucleus substitution by a substituent contg. an Si atom and SO2. CONSTITUTION:This material is constituted of the positive type resist material consisting of the copolymer of the styrene deriv. subjected to the nucleus substitution by the substituent contg. at least one Si atom and the SO2 and, for example, the copolymer is expressed by the formula I. In the formula I, X denotes H or alkyl group; l is >=1; Z denotes {Si(CH3)3}l, etc. The styrene deriv. subjected to the nucleus substitution by the substituent contg, the Si atom is used in this way. The selection ratio with the lower flattened layer in O2B-RIE (reactive ion etching using oxygen) is improved in this way. The decomposition efficiency when the resist is irradiated with radiations is, therefore, enhanced by introducing the C-S bond of small total energy into the main chain. The positive type resist having the practicable sensitivity is thus obtd.

Description

[Detailed Description of the Invention] (Summary) This invention relates to a positive resist material and a pattern forming method using the same as a radiation-sensitive upper layer resist in a two-layer resist method, while having a practical sensitivity of the conventional level. The purpose of the present invention is to provide a positive resist material for the upper layer in a two-layer resist having a higher selection ratio with respect to the lower planarization layer, and to provide a method for forming a resist pattern using this resist material, and at least A positive resist material is made of a copolymer of SO□ and a styrene derivative in which at least one nucleus is substituted with a substituent containing one Si atom, and this material is used as an upper layer resist to form a resist pattern in a normal process. Configure to form.

[Industrial Application Field] The present invention relates to a resist material and a pattern forming method using the same. More specifically, the present invention relates to a positive resist material and its use in a radiation-sensitive upper layer resist in a two-layer resist method. The present invention relates to a method of forming a pattern.

The resist material and pattern forming method according to the present invention include:
Used for microfabrication in the manufacture of semiconductor integrated circuits (semiconductor devices).

[Prior Art] In recent years, semiconductor devices such as ICs and LSIs have become thinner and more highly integrated, and resists require high sensitivity, submicron-level resolution, and Dry etching resistance is required. and,
As miniaturization progresses, it is difficult to form a highly accurate resist pattern using a single layer resist due to the step differences that occur on circuit boards. In order to solve this problem, various methods have been proposed to improve overall performance by forming resist into multiple layers and assigning functions to each layer, and the two-layer resist method is an effective method.

In the two-layer resist method, a thick organic flattening layer is formed on the surface of the circuit board, a thin layer of resist material with good dry etching resistance is applied on top of the layer, and this upper resist layer is patterned by exposure and development. Then, the flattening layer is dry developed using oxygen or active ion etching (0□-RIE).

In this way, a resist pattern that can be processed more finely than before can be formed. This upper layer resist is required to have high sensitivity, high resolution, and excellent resistance to 0□-RrE. Silicon (Si)-containing polymers are used as resists for this upper layer, for example,
Poly (trimethylsilylmethyl methacrylate)...
・Formula A, poly(trimethylsilylmethyl α-chloroacrylate)...2B, or...Formula C1 are known.

C8゜ CH3 l +CH2-C-+-r-+SO2→1 CH,...C LCSi CH3 CH.

[Problems to be Solved by the Invention] The silicon-containing polymer upper layer resist as described above has a selectivity ratio of 02 RIE with respect to the lower planarization layer of 20.
It is not that large and is still insufficient for practical use.

An object of the present invention is to provide a positive resist material for the upper layer of a two-layer resist that has a practical sensitivity comparable to that of the conventional one and has a higher selection ratio with respect to the lower flattening layer. An object of the present invention is to provide a method of forming a resist pattern using a resist material.

Means for Solving Problem C] The above object is achieved by a positive resist material comprising a copolymer of SO2 and a styrene derivative in which at least one nucleus is substituted with a substituent containing at least one Si atom. .

It is preferable that the above copolymer is represented by the following formula.

In the formula, X represents H or an alkyl group, and Z is (5i(CHx)+lI(N(S
i(C1l□)°)), (N (St(C1:+)+) z) 1! represents one of 1 or more.

Furthermore, the above-mentioned copolymer polymer material can be used as an upper layer resist (positive resist layer) in a two-layer resist method to form a resist pattern in a normal process.

(Function) According to the present invention, since a styrene derivative having at least one nucleus substituted with a substituent containing at least one Si atom is used, the selectivity with respect to the lower flattening layer in 0□-111E can be improved. Can be done.

By forming a copolymer of this styrene derivative and SOz, the main chain contains ul C-
By introducing three bonds, the decomposition efficiency when irradiated with radiation (ultraviolet rays, deep ultraviolet rays, X-rays or electron beams) is increased, and a positive resist having practical sensitivity can be obtained.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiment examples of the present invention.

Toluene 50 and 50210 were added to 10 g of p-trimethylstyrene obtained from p-chlorostyrene and trimethylsilyl chloride by Grignard reaction.
0ml was introduced, AIBN was added as a polymerization initiator,
The copolymer (
Polymer) was obtained. It was purified by the reprecipitation method, with a molecular weight of 50,000, a degree of dispersion of 2, and a composition ratio of styrene and SO2 (m:
n) A 7:3 copolymer was obtained. This polymer was spin-coated onto a silicon wafer using cyclohexanone as a solvent, and baked at 180 DEG C. Cl2O for minutes to form a resist layer with a thickness of 0.3 mm. This resist layer is coated with an electron beam (acceleration voltage: 20
1,4-dioxane/IP
It was developed for 60 seconds using a developing solution of A=2/1. As a result, the sensitivity of this resist layer is Eth=10μC/
afl, and a practical one was obtained.

Next, a novolac-based resist (O
FPR-800, Tokyo Ohka Kogyo product) at 2.0 an
It was coated with a spin code to a thickness and baked at 200°C for 60 minutes to form a lower resist (flattening layer).

On top of that, the above-mentioned copolymer is applied in the same manner to form an upper layer resist, exposed to electron beam in the same manner, and developed to form an upper layer resist pattern of 0.3 tone line and space (positive type).
I got it. Using this pattern as a mask, perform 02 RIE (
Oxygen 50SCCM, 0.06Torr, 50W
) for 25 minutes. As a result, the pattern was transferred to the lower resist without any dimensional shift. At this time, the amount of film loss of the upper layer resist is approximately 50t+m
The selection ratio was 40 times.

Uratanemasu 1 (bistrimethylsilyl)acinostyrene (Shin-Etsu Chemical)
DMF (dimethylformamide) 50 for 10g
100 m7 of a/and soz were introduced, AIBN was added as a polymerization initiator, and the reaction was carried out at a reaction temperature of 50°C for about 30 hours to obtain a copolymer. It was purified by the reprecipitation method, with a molecular weight of 50,000, a dispersity of 2.9, and a composition ratio (m:n) of 2.
:1 copolymer was obtained.

This copolymer is prepared as a 1,4-dioxane solution.

On the other hand, as in Example 1, 0FPR-
800 was applied with spin cord to a thickness of 2.0μ, and the angle was 200°.
Baking for 60 minutes at
). The copolymer-containing solution was spin-coated to a thickness of 0.34 mm on this lower resist layer, and baked at 180° C. for 20 minutes to form an upper resist layer. Then, in the same manner as in Example 1, the upper resist layer was exposed to an electron beam and developed with THF (tetrahydrofuran) for 20 seconds to obtain an upper resist pattern (positive type) with 0.3μ line and space. The sensitivity of this upper layer resist is 15
It was μC/Cshi.

Next, using the upper resist pattern as a mask, do the same as in Example 1 with 02-1? As a result of etching with IE,
The pattern was transferred to the underlying resist without any dimensional shift. At this time, there was almost no film loss in the upper resist layer, and the selectivity was 100 times or more.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a positive resist for an upper layer that has the same practical sensitivity as the conventional one and has an excellent selectivity with respect to the lower resist (flattening layer), and has a finer resist pattern that is more advanced than the conventional one. enables the formation and microfabrication of

Claims (1)

[Claims] 1. A styrene derivative having at least one nucleus substituted with a substituent containing at least one Si atom, and SO_2
A positive resist material made of a copolymer with 2. The material according to claim 1, wherein the copolymer is represented by the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X represents H or an alkyl group, l is 1 or more, and Z is {Si(CH_3)_3}_l{▲There are mathematical formulas, chemical formulas, tables, etc.▼ }_l, {N[Si(CH_3)_3]_2}_l. 3. In a two-layer resist method in which a flattening layer of an organic substance is formed on a semiconductor circuit board, a thin film of a polymeric material is formed thereon, and a pattern is formed, the polymeric material according to claim 1 or 2 is used. A pattern forming method characterized by using a positive resist material.