JPS6070442A - Formation of pattern - Google Patents

Abstract

PURPOSE:To enhance plasma resistance and sensitivity without high resolution of a PMMA type resist material by using a copolymer of methyl methacrylate and alpha-methylstyrene as the resist material. CONSTITUTION:A copolymer of methyl or ethyl methacrylate and alpha-methylstyrene is used as a resist material. As the moiety of copolymn., alpha-methylstyrene is preferred from the view points of radiation, such as X-rays or electron beams, decomposability, i.e., the presence of a quternary carbon at the alpha- position, that of an aromatic ring, simple structure, easy availability, and high contrast similar to PMMA. A preferable methacrylate/alpha-methylstyrene copolymn. ratio is 20:80-80:20. Sensitivity of the resist material can be enhanced by coating a substrate with a mixture of said copolymer and a cross-linking agent and cross-linking the copolymer in advance to insolubilize it, then, selectively exposing it to electron beams, or the like to partially decompose the cross-linked parts, and at the time of development, dissolving them with a solvent high in dissolution power to force development.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a pattern forming method, and more particularly to a pattern forming method utilizing phosphorography technology and using a resist.

Prior Art and Problems The use of lithography techniques for microfabrication is well known. With the miniaturization of semiconductor devices, exposing a resist to electron beams or the like has become increasingly advantageous. Polymers of methacrylic acid esters, such as polymethyl methacrylate (PMMA), have been studied as P-type lenosts that are sensitive to electron beams, and are still widely used to achieve high resolution.

However, this system has very poor plasma resistance and cannot achieve high sensitivity.

The ester moiety of polymethacrylic acid ester is replaced by a bulky alkyl group (the volume occupied by the atomic group is large) or l1ii1f.
Autopsies have also been conducted on substances substituted with aromatic rings such as benzene rings, which are said to have lasma properties, but the plasma resistance and sensitivity are hardly affected, and the resolution is lower than that of PMMA (Wayne M. , Moreau +5PIE V
ol, 333 Submicron Lithogra
phy+1982, see).

OBJECTS OF THE INVENTION It is an object of the present invention to improve plasma resistance and sensitivity without losing the high resolution of the P-Obutsu system, and to use it for pattern formation, given the above prior art vc<c+a.

Structure of the Invention In order to achieve the above object, the present invention provides a pattern using a copolymer of methacrylic acid ester (herein, the alkyl group is a methyl group or an ethyl group) and α-methylstyrene as a resist material. A forming method is provided.

The present invention does not rely on PMMA-based derivatives, but rather on PMMA-based derivatives.
The above object is achieved by copolymerization with A yarn. As a copolymerization partner, it is radiation (X-ray) decomposable (having a quaternary carbon purple at the α position), has an aromatic ring, and has a simple structure, is easy to obtain, and is comparable in strength to PMMA. α-methylstyrene was preferred because it has a high contrast property. The copolymerization ratio of methacrylic acid ester and α-methylstyrene is 20:80-8
o: It is preferable that it is 20. If the amount of α-methylstyrene is too low, plasma resistance cannot be expected, and if it is too high, the sensitivity will decrease, so it is preferably within the range of 20 to 80%. This copolymer is represented by the structural formula 1.

However, this copolymer alone does not provide sufficient sensitivity;
It is 5X10-5C/σ2 or less. Therefore, this copolymer alone has no choice but to be used as one layer of a multilayer resist, similar to PMMA yarn. Therefore, this copolymer and a crosslinking agent are mixed and applied, crosslinked and insolubilized in advance, and then selectively exposed to electron beams etc. to partially decompose the crosslinks. Forced development with a solvent results in improved sensitivity of the resist material. As a crosslinking agent, an azide compound such as 4.
4'-Diazidochalcone: p-azidobenzoic acid: N'(SatoshitoC00Hp-atacetophenone: N-diazidechalcone: p-sulfonylazobenzoic acid: HOOC-g>5o2N3, etc.) are preferably used.

Invention Example 5 - 60:4Q of α-methylstyrene and methyl methacrylate
A copolymer was prepared, and this copolymer and 4,4'-diazide chalcone were dissolved in teff4-lucerone rugacetate at a ratio of 80:20 (weight ratio). After filtering this mixed solution, it was spin-coded onto a silicon wafer to a film thickness of 0.5 μm.
After that, it was baked at 170° C. for 60 minutes in a nitrogen atmosphere. After selective exposure to an electron beam with an accelerating voltage of 2° keV, development was performed using a Metelceron loop.

An M image of 1 μm line/space was taken at a sensitivity of 7.2×10−′ C/1wr2.

When plasma treated with 02+CF4 gas (5-95%) (200W, 0.1 torr), PIII
It showed about 4 times the plasma resistance of MA.

Example 2 The same treatment as in Example 1 was carried out using methacrylic acid ether instead of methyl methacrylate. Sensitivity 9×1O-6C/c
It exhibited an image resolution of 7.m'' with a line/space of 1 μm, and had plasma resistance against 02+CF4 gas that was about 4 times that of pm.

Example 3 The same treatment as in Example 1 was carried out using p-azidopendelacetone as the crosslinking agent. - D□=8X10-'C/z2 E, B, sensitivity,
A 0.8 μrn line/space coverage was obtained. The plasma resistance (CF4102:9515) was about 4 times that of PMMA.

Example 4 α-menalsterene/metelco I methacrylate remer (
40:60), a total of 10,000 animals were combined and processed in the same way.

DO=5.2X10-” C7cm2 resolved 1μm line/space.02/CF4 (5/95)
The plasma resistance against force is about three times that of PMMA.
-O Effects of the Invention As is clear from the above description, the present invention makes it possible to form fine patterns by electron beam exposure using a highly sensitive and plasma-resistant digital resist.

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

Claims (1)

[Claims] 1. A copolymer of Nisder methacrylate (here, the ester is an alkyl group, and the alkyl group is a methyl group or an ethyl group) and α-methylstyrene is used as a resist material. A pattern forming method. 2. A pattern forming method according to claim 1, characterized in that a mixture of the co-1 combination and a crosslinking agent is used as a resist material.