JPH01187545A - Positive type photoresist material - Google Patents

Abstract

PURPOSE:To obtain a resist material for X-ray exposing which has high sensitivity and excellent dry etching resistance by using specific polysulfone. CONSTITUTION:The polysulfone expressed by the formula I is used as the positive type resist material. In the formula, R denotes hydrogen or alkyl group; R' denotes a t-butyl group or phenyl group; n denotes >=10 integer; m denotes 0 or <=5 integer. Since this material has a t-butyl dimethyl silyl group or dimethyl phenyl silyl group at the terminal of the side chain, the material has the high etching resistance to oxygen plasma. The positive type resist which has the high sensitivity to electron rays and X-rays and the high resistance to oxygen plasma etching is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resist material that is sensitive to high-energy rays such as electron beams and X-rays and is suitable for microfabrication technology.

[Prior Art] As LSIs become more highly integrated, more advanced microfabrication techniques are required. Now that batten dimensions on the order of sub-microns are coming into practical use, highly accurate microfabrication technology is essential for K in order to keep errors in batten transfer within tolerance.

However, optical exposure, which is a conventional general-purpose technique, is approaching the resolution limit due to the wavelength of light, making it difficult to meet such technical demands.

Against this technical background, exposure technology using X-rays and electron beams, which have extremely small resolution limits depending on wavelength, will become increasingly important in the future. Electron beam exposure technology has already been put into practical use in the field of manufacturing mask patterns for LSI manufacturing) and is a highly complete microfabrication technology. It is also being used as a processing technology for manufacturing custom L8 machines that involve small-lot, multi-item production. However, as the pattern becomes finer, the nulput decreases significantly, so there is a problem when electron beam exposure technology is used as a mass production technology in LSI manufacturing.

Therefore, we are aiming to establish a technology that enables high-precision machining and mass production.
Research and development of exposure technology using 80R) and the like is being actively conducted. However, the SOR technology is currently in the research and development stage, and although the exposure equipment for the X-ray exposure technology is highly complete, the conventional problem of low throughput has not yet been solved.

As explained above, low throughput is the biggest problem in exposure technology using electron beams and X-rays, and in order to solve this problem, there is an urgent need to increase the sensitivity of resist materials.

Furthermore, after several steps have been carried out, a step-like bump is formed on the surface of the substrate. On such a stepped substrate, it is difficult to miniaturize a pattern because the thickness of a single resist layer is not constant. As a way to solve this problem, multilayer resist, especially [2]
Layered resists are attracting attention. The lower layer is coated with an organic polymer and flattened, and the upper layer is coated with a material that has batten forming ability and etching resistance for processing the lower resist, usually oxygen dry etching resistance. After forming a pattern on the upper layer, it is dried. This is a method of forming a button in the lower layer by etching.For example, Morita et al., Japanese Journal of Applied Physics (J
pn, J, Appl, Phys, ), Volume 22,
No. L659 (1983)]. As such a 22-layer resist material, a resist containing metal atoms, particularly silicon atoms, is attracting attention from the viewpoint of high oxygen dry etching resistance.

Conventionally, fluorine-containing methacrylate-based resists have been well known as resists for high-sensitivity electron beams and X-rays.
electrochem, Soc, Vol. 124, p. 1648 (1977)], but had the drawback of low dry etching resistance. Poly(olefin sulfone) is also a highly sensitive electron beam resist material, but similarly has low dry etching resistance. Polysulfones with increased dry etching resistance by introducing F-lymethylsilyl groups into their side chains have also been reported [Gotzdz et al.
Polymer Engineering and Science (Polymer Engineering and Science)
lymer Engineeringand 5cie
nce), Vol. 26, p. 1123 (1986)]
However, introduction of trimethyμsilyl group does not provide sufficient oxygen plasma etching resistance. On the other hand, as a highly resistant resist, φ-MAC [Harada et al., Engineering 1! ! KIn) Funzaku V Yonzu Elect c
in devices!! EK TranaFil
ec-tron Devices), Volume KD-29,
See page 518 (1982) 1. OMB [Imamura], Journal of Electrochemical Society (J, Electrochem, Bo
a), Vol. 126, p. 1628 (1979)]
etc., but the sensitivity is lower compared to polysulfone etc.

[Problem to be solved by the invention]

Until now, a resist material that has both high sensitivity and dry etching resistance has not yet been developed.

An object of the present invention is to overcome the drawbacks of the prior art and to provide a resist material for X-ray exposure that has high sensitivity and excellent dry etching resistance.

[Means for Solving the Problem] To summarize the present invention, the present invention relates to a positive resist material, which has the following general formula I: (wherein R is hydrogen or an alkyl group, R2 is 1-butyl group or phenyl group, n
is an integer of 10 or more, m is an integer of 0 or more and 5 or less), and is characterized by being highly sensitive to high-energy rays and having high resistance to oxygen plasma etching. shall be.

The material of the present invention has high etching resistance against oxygen plasma because it has a terminal Kt-gtyldidimethinelyl group or dimethylphenylsilyl group in the side chain. If this substituent is a trimethylsilyl group, the surface of the resist film becomes rough during oxygen dry etching, and the resistance is so low that the underlying resist cannot be processed. When a bulky substituent is attached to a silicon atom, resistance increases, but if a substituent is too bulky, the decomposition reaction during exposure that causes the main chain to cleave due to a zipper reaction is suppressed, resulting in a decrease in sensitivity. for that,
As substituents attached to the silicon atom, there are two methyl groups,
One bulky t-butyl group or phenyl group is preferred. In addition, the longer the methylene length between the main chain and the silicon atom, the higher the G value for decomposition, but if it is too long, the dissolution rate ratio between the exposed and unexposed areas during development will not be large. Resist sensitivity decreases. Furthermore, since the weight fraction of silicon content becomes small, the resistance to oxygen dry etching is reduced. Therefore, the length of methylene is 0 or more and 5
The following is good.

The molecular structure of the silicon-containing polysulfone in the present invention is:
Does not impair the self-developability of ordinary poly(olefin sulfone). After exposure, when heated to 60 to 100° C. under reduced pressure, the polysulfone in the exposed area is volatilized and can be self-developed to form a black oxide. The baton formation by self-development not only simplifies the development process, but also eliminates the use of a developing solvent, making VC3J! There is no problem of environmental pollution, which is advantageous.

Various methods have been reported for synthesizing polysulfone, such as thermal polymerization, free radical polymerization, and polymerization by ultraviolet irradiation. In the present invention, the synthesis method is not limited, but in the examples, a thermal polymerization method using azoisobutyronitrile and a t
A free physical polymerization method using -BuOOH (t-butyl hydroperoxide) was used.

Synthesis examples of polysulfone used in the present invention are shown below, but the invention is not limited thereto.

Synthesis Example 1 Poly(dimethylphenylsilylvinyl sulfone) (In general formula I, m=0, R=H1R'=phenyl group) After replacing the inside of the polymerization tube with argon gas, while cooling with liquid nitrogen, dimethylphenyl 30 μ of vinylsilane 1f1 azobisisobutyronitrile/L/(mu-N) was introduced into the polymerization tube. Furthermore, 4Cso gas was introduced to trap liquid So at about 101F. Freezing - thawing process 2
After repeating the reaction several times, the tube was sealed and reacted at 20°C for 20 hours.

The polymerization tube was opened and acetone was added to dissolve the polymer, and then poured into hexane to obtain a white solid polymer.

Synthesis Example 2 Poly(t-butyldimethylsilylvinyl sulfone) (In general formula I, m = 0, R=H%R'=t-
In the case of butyl group) After replacing the inside of the polymerization tube with argon gas, N3019 from 1t% A of t-butyldimethylvinylsilane was introduced into the polymerization tube while cooling with liquid nitrogen. Further [SO2 gas was introduced, and about 1012 liquid SO2 was added.

was trapped. After repeating the freezing-inflation-thawing process twice, the tube was sealed and reacted at 30°C for 20 hours. After opening the polymerization tube and adding acetone to dissolve the polymer,
A white solid polymer was obtained by pouring into hexane.

Synthesis Example 3 Poly(2-methyl-dimethylphenylsilylvinyl sulfone) (In general formula I, m = 01R=OH3, R'=
In the case of phenyl group) After replacing the inside of the polymerization tube with argon gas, add 1 ton of isoprobenyldimethylphenylsilane while cooling with liquid nitrogen.
was placed in a polymerization tube. Furthermore, 80, gas was introduced, and about 1O
The liquid So of f was trapped. t-BuOOH [
11-Drop and cool with ethanol-liquid nitrogen
Cooled to ℃. After reacting for 20 minutes, acetone was added to dissolve the polymer, and then poured into hexane to obtain a white solid polymer.

Synthesis Example 4 Poly(2-methyl-t-butyldimethylsilylvinyl
sulfone) (In general formula I, m=o, R=(1!H3, R'=
In the case of t-butyl group) After replacing the inside of the polymerization tube with argon gas, add t-butylisobrobenyldimethylsiphon 1 while cooling with liquid nitrogen.
t was placed in a polymerization tube. Furthermore, we introduced day 0 gas, and about 10
I poured 1P of liquid 803. Add 0.1 drop of t-BuOOH and cool with ethanol-liquid nitrogen coolant.
Cooled to 0'cK. After reacting for 20 minutes, acetone was added to dissolve the polymer, and then poured into hexane to obtain a white solid polymer.

Synthesis Examples 5-12 Polymers with m = 2.15 were synthesized according to the methods of Synthesis Examples 1-40. Table 1 shows (m %) of the synthesized polymers.
Rs R''). Both were obtained as white solids.

〔Example〕

Hereinafter, the present invention will be specifically explained using examples, but the present invention is not limited to these examples.

Example 1 The polysulfone of Synthesis Example 1 was spin-coded onto a silicon substrate, prebaked at 80° C. for 10 minutes, and then electron beam resist properties, X-ray resist sensitivity, and oxygen plasma etching resistance were examined. The electron beam resist sensitivity was evaluated using ESM-601 manufactured by Elionix Co., Ltd. at an accelerating voltage of 20 KV.

X-ray resist sensitivity was evaluated using X-rays with a wavelength of -5.4A. Development was carried out at 25° C. for 1 minute using a 50N0 mixed solution of n-amyl acetate and isopropyl alcohol. The polysulfone of Synthesis Example 1 exhibited positive resist characteristics with respect to electron beam exposure, and the sensitivity was 29 μOZi. It also showed positive resist characteristics with respect to X-ray exposure, with a sensitivity of 250 m17 cm. Oxygen plasma etching resistance was measured using DIM-451 (manufactured by Anelva).
Using a parallel plate type) etching device, output = 50W,
Bias = α6 KV, flow rate = 508 CcM1, pressure =
Evaluation was made at 10 mTorr. The etching speed is 1
The resistance was 7 times that of AZ1450 (Silapray) at 5 nm/min.

Examples 2 to 12 Table 1 shows electron beam (EB) results of positive resist materials according to the present invention.
) Sensitivity, X-ray sensitivity, and etching rate for oxygen plasma were summarized. The same evaluation method as in Example 1 was used. In all cases, a mixed solution of n-amyl acetate and isopropyl alcohol was used as the developer.

Table 1 Synthesis example m RR' EB sensitivity X-ray sensitivity Elatin residual carbon 10 hydrogen F〉29 250 15
20 hydrogen t-yu 1223o11 3 0 methyl phase 20
250 154 0 Methi/L't-bu?
/9 10 210 1252 hydrogen
7LA/318o17 62 hydrogen on one hand 2 150 137 2
Methyl phenyl'l' 3 190
158 2me fyvt-y9-yv
2 160 f495 hydrogen 7:X:A
' 3180 17105 hydrogen t 2
150 1311 5 Methyl Fetish IL
' 3 190 1512 5
Methyl t-butyv 2 160
14 [Effects of the Invention] As explained above, the present invention provides a positive resist that is highly sensitive to electron beams and X-rays, and has high resistance to oxygen plasma etching. The present invention aL
It is useful for microfabrication technology in 8-stage manufacturing.

Claims (1)

[Claims] 1. The following general formula I: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, R is hydrogen or an alkyl group, and R' is a t-butyl group or a phenyl group. , n is an integer of 10 or more, and m is an integer of 0 or more and 5 or less), and has high sensitivity to high-energy rays and high resistance to oxygen plasma etching. A positive resist material characterized by: