JPS6070448A - Formation of pattern - Google Patents

Abstract

PURPOSE:To form a plasma resistant resist pattern with high sensitivity and resolution by using a specified polymer for the resist material. CONSTITUTION:A polymer to be used as a resist material has, as side chains, benzene rings each having a carboxyl group and an electron attractive group at the o- or p-position with respect to each carboxyl group. Such a polymer is represented by one of formulae I -IV in which X is a carboxyl group and Y is an electron attractive group. Since such a polymer is extremely lowered in polarity by irradiation of electron beams, a negative pattern is obtained by using a polar solvent for development, and a positive pattern is obtained by using a nonpolar solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a pattern forming method, and particularly to a pattern forming method that utilizes a change in polarity of a resist material caused by electron beam exposure.

Conventional technology and problems Using lithography technology, resist is applied onto a substrate, selectively exposed to energy rays, and developed to create a resist pattern, and this resist pattern is used to select the substrate. Techniques for etching and ion implantation? Jo is widely used. The resist used for this pattern formation is generally both negative and positive.
This method makes use of the difference in solubility in a developer based on the difference in the molecule if of the unexposed area and the exposed area of the resist material. I can't.

Therefore, as another method of forming a resist pattern, a method has been proposed that utilizes a change in polarity of a resist material due to exposure. However, since the conventionally proposed products combine a base polymer and a crosslinking agent, there are problems with compatibility and stability, and r61M
was also not sufficient.

OBJECTS OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a pattern forming method that utilizes the change in polarity of a resist material due to exposure and is excellent in both resolution and (Hf).

Structure of the Invention In order to achieve the above object, the pattern forming method of the present invention uses a polymer having a carboxyl group and a benzene ring as a side chain having an electron g & 51 group at ortho or distal positions with respect to the carboxyl group as a resist. It is used as a material and subjected to electron beam exposure.

In order to solve the problems of compatibility and stability, the present invention explores a simple homopolymer type that does not use a crosslinking agent and whose polarity changes with energy rays. As a result of research by introducing various functional groups, it was found that when a polymer like the one described above is irradiated with an electron beam, a difference in polarity occurs between the exposed and unexposed areas, and this was completed. A typical structure of this polymer is, for example, [wherein, X represents a carboxyl group and Y represents an electron-withdrawing group]. ]. It is not necessary that all benzene Ru has one electronic group such as carboxyl group and No2 group,
A copolymer with styrene may also be used.

be. In addition to No2 group, -ON is used as the electron-withdrawing group.

-8o, H, etc. Additionally, a benzene ring that does not have a carboxyl group or an electron-withdrawing group typically does not have a] substituent, but it does have a methyl group or ethyl group that does not affect the polarity change. It's okay. The molecular weight of this polymer is several 1 ooo A4.1 million, especially s, o o o
It is preferable that it is 80,000.

When this polymer is irradiated with an electron beam, its polarity is significantly reduced, so when a polar solvent is used during development, a negative pattern is obtained, and when a non-polar solvent is used, a positive pattern is obtained. In particular, in the case of negative mode, submicron regions can be easily resolved because no swelling occurs during development. The sensitivity depends on the degree of film reduction during development, but in practice, a sensitivity of 1 to 3 x 1O-5a/di or more is achieved.

This polymer is dissolved in a solvent such as cellosolve acetate and applied onto a substrate, and a pattern is drawn using an electron beam.

MIBK fx is developed using a polar solvent, while positive mode is developed using a non-polar solvent such as benzene, xylene, toluene, or niheptane. In addition, conventional pattern forming methods can be used.

Examples of the Invention Example 1 A copolymer was synthesized by mixing p-carboxy-m-nitrostyrene with a segment ratio of 70:30 in dioxane and heating. This copolymer was separated and purified, dissolved in cellosolve acetate, spin-coded onto a silicon wafer, and beta-coated at 50 to 60 C for 80 minutes to form a 1 μm thick film. Add to this the accelerating voltage 2 Q KeV
The turn was drawn using an electron beam.

Thereafter, it was developed with benzene to obtain a positive pattern, and developed with an acetone/isopropyl alcohol mixed solvent to obtain a negative pattern. Film thickness after development is 0.7-0.8
It is μm. 15μm line/space in positive mode,
In negative mode, it was possible to resolve 0.9 to 1.0 μn+ lines/spaces. The sensitivity was about 20×10-”o/cn!.1iiJ plasma property was OF 4102 (5/95
) When etched with gas, it was about 5 times as high as PMMA. Example 2 An experiment similar to Example 1 was carried out using m-carboxy-0-nitroxylene instead of p-carboxy-m-nitrostyrene. Similar results to Example 1 were obtained.

Example 6 Homopolymer of p-carboxy-m-nitrostyrene (
Similar processing was performed using Mw*70,000). Sensitivity is 8.7 x 10-' c/cl and 0.9 for both negative and positive. Iza line was resolved.

Effects of the Invention As is clear from the above explanation, the present invention provides a pattern forming method that utilizes changing the polarity of a polymer by electron beam exposure and provides a plasma-resistant resist pattern with high sensitivity and high resolution. be done.

Claims (1)

[Claims] A polymer having a carboxyl group and a benzene ring as a side chain having an electron-withdrawing group at the ortho or para position relative to the carboxyl group is coated on a substrate, and selectively exposed to an electron beam. A pattern forming method characterized by performing development with a solvent by utilizing the polarity change of the polymer, thereby obtaining a negative or positive resist pattern.