JPS6069647A - Formation of pattern - Google Patents

Abstract

PURPOSE:To enhance sensitivity of a resist material to high energy rays in pattern forming by using a copolymer of a monomer having a carboxyl group and a monomer having an aromatic ring for the resist material. CONSTITUTION:(A) A monomer having at least one carboxyl group and at least one polymerizable unsatd. bond, such as acrylic acid, is copolymerized with (B) a monomer having an aromatic ring, such as styrene, to prepare a copolymer, such as styrene-acrylic acid or methacrylic acidalpha-methylstyrene copolymer. A base is coated with a solvent soln. of said copolymer for forming a resist material and after prebaking, selectively exposed to electron beams, etc. An intended pattern is obtained by developing it with a proper developer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for forming a /4' turn, and more particularly to a method for forming a pattern in which the sensitivity of a resist material to energy rays is improved.

Prior Art and Problems Many types of positive and negative resist materials for microfabrication are known and used, but their development is still progressing. This is because advances in phosphorography technology are one of the important driving forces behind the continuous advancement of semiconductor devices. As for resist materials, there is a need for materials that satisfy the basic requirements of being able to be exposed to electron beams and having excellent dry etching resistance, as well as other conditions such as resolution, sensitivity, heat resistance, and ease of handling. However, for example, when it comes to materials that are sensitive to high-energy rays and have excellent dry etching resistance and heat resistance, there are currently only a limited number of materials that are sensitive to high-energy radiation, and it is difficult to find materials that have particularly excellent sensitivity. It's not always easy.

Conventionally, methods for directly improving the sensitivity of resist materials include modifying resist materials with functional groups such as C1*BrhCN (e.g., chloromethylated styrene), and mixing radiation-sensitive compounds such as azide compounds into resist materials. Several methods have been used, but none have shown sufficient performance.

OBJECTS OF THE INVENTION In view of the above-mentioned conventional techniques, an object of the present invention is to improve the sensitivity of a resist material in pattern formation.

Structure of the Invention The present invention achieves the above object by using a copolymer of a monomer containing a carboxyl group and a monomer containing an aromatic ring as a resist material.

As a result of various experiments, the present inventors have discovered that carboxyl groups exhibit high sensitivity to energy rays, particularly electron beams, and have accomplished the present invention.

A monomer containing a carboxyl group is one that contains at least one carboxyl group and has at least one unsaturated bond for polymerization. 1 to 7 carbon atoms as side chain
It may contain about 1 to 3 linear groups and/or about 1 to 3 cyclic groups. However, it is generally preferred that the side chains are not too large. The carboxyl group does not necessarily need to be attached to the main chain, but may be attached to the side chain. Typical examples include acrylic acid, methacrylic acid, methylene succinic acid, and other styrene or α-methylstyrene derivatives.

Another feature of the resist material of the present invention is that it is copolymerized with a monomer containing an aromatic ring, and the hK improves dry etching resistance and heat resistance. On the other hand, when the resist material contains an aromatic ring in order to read the dry etching resistance and heat resistance, the sensitivity of the present invention is improved by copolymerizing a monomer containing a carboxyl group. It is a characteristic. This monomer containing an aromatic ring is under the same conditions as the monomer containing a carboxyl group, except that it necessarily contains at least one aromatic ring but does not necessarily contain a carboxyl group. It is. Typical examples include styrene, carboxystyrene, vinylnaphthalene, and vinylanthracene.

The copolymer of the present invention may contain an aliphatic monomer not containing a carxyl group, in addition to a monomer containing a carxyl group and a monomer containing an aromatic ring monomer.

In any case, it is preferable that the overall proportion of acid (seven acids) in the copolymerization is 40 or less, particularly gauze coefficient to several tens of coefficients. This is because if the acid copolymerization ratio is too large, the applied resist film tends to be thinned, and if it is too small, the effect of improving sensitivity cannot be obtained. Moreover, since the copolymer according to the present invention has good compatibility with an azide compound,
It is particularly effective to mix an azide compound to improve sensitivity.

The above resist material is dissolved in a solvent and applied onto a substrate, prebaked, and then selectively exposed to an electron beam or the like.
The pattern is then formed using conventional techniques such as development and post-baking.

Examples of the invention Examples of the invention will be described below.

Example 1 Polystyrene has been widely studied and used as a negative resist with excellent dry etching resistance, but its sensitivity, especially the sensitivity to electron beams (generally I
, 2) had the disadvantage of being low.

Styrene and acrylic acid were copolymerized at a ratio of 7=3 to create a polymer with a molecular weight of about 100,000. The sample was dissolved in methyl cellosolve acetate (MCA) and spin-coded onto a silicon wafer to a thickness of 1 μm. Accelerating voltage 20
It was selectively exposed to a keV electron beam and developed with MCA. Sensitivity is Dg=3.5X10C
//crn' resolved 1 μm lines/spaces.

Sensitivity is improved by more than 91 orders of magnitude compared to polystyrene.

However, this copolymer is a negative-tone resist material.

Example 2 α-methylstyrene and methacrylic acid were copolymerized at a ratio of 7:3 to create a 2-limer with a molecular weight of approximately 790,000. Dissolve this in MCA and place it on a silicon wafer to a thickness of 1 μm.
I made a spin code. Methyl isobutyl ketone (MIBK) was selectively exposed to an electron beam with an accelerating voltage of 20 keV.
) was developed. The sensitivity was 4.2 x 10-6c/.2, and 1 μm lines/spaces were resolved. Sensitivity is improved by more than an order of magnitude compared to polystyrene. This copolymer is in the tenon form.

Comparative Example α-Methyl-p-hydroxystyrene was prepared according to a conventional method.
Polymerization was conducted to obtain a polymer with a molecular weight of approximately 30,000.

On the other hand, for comparison, α-methylstyrene, 391Jmer (
A molecular weight of approximately 40,000) was also used. In the former, sensitivity 1, OX
10-” C/crn!, but the latter is I
The sensitivity was low at 0-'C/crn2. The treatment method was the same as in Example 2. The resolving power is almost the same, it resolves a line of 0.3 Pw, and it is an excellent positive resist.

Effects of the Invention As is clear from the above explanation, the present invention improves the sensitivity of the resist material in a pattern forming method using lithography technology.

patent applicant Fujitsu Limited patent application agent Patent attorney Akira Iku Patent attorney Kazuyuki Nishidate Patent attorney 1) Yukio Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. A pattern forming method characterized by using a copolymer of a monomer containing a carboxyl group and a monomer containing an aromatic ring as a resist material.