JPH01215812A - Polyacrylic acid derivative - Google Patents

Abstract

PURPOSE:To obtain a positive type resist material improved in dry etching resistance and having high sensitivity and high resolving power by using a polyacrylic acid derivative represented by a specified structural formula containing halogen and benzene rings. CONSTITUTION:A positive type resist improved in dry etching resistance and having high sensitivity and high resolving power is produced by using a halogenated polyacrylic acid ester derivative of the given formula (wherein R1 and R2 are each H or F-substituted methyl, and they are not H at the same time; Y1-Y5 are each H or F; Rt is F-substituted alkyl; m and n are each a positive integer with the n/m being 1 or below) that is a copolymer of an acrylic ester having a Cl atom. in the alpha-position and an F atom. and a benzene ring in the ester part with an acrylic ester of which ester part is F-substituted alkyl.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a polyacrylic ester containing halogen and benzene rings that can be used as a resist material sensitive to radiation such as electron beams, deep ultraviolet rays, and X-rays. The present invention relates to a derivative and a method of forming a pattern using the polyacrylic acid ester derivative.

[Prior Art] Polymethyl methacrylate (hereinafter abbreviated as PMMA) is well known as an electron beam positive resist. PMM
Although A has high resolution, it has low sensitivity and poor dry etching resistance. In addition, with the aim of increasing favorability (1),
Polymers of esters of (meth)acrylic acid or its derivatives with mono- or polyfluoroalkanols are used as positive-type resins for pattern formation by electron beams, etc. (Japanese Patent Laid-Open No. 18638/1983) , Japanese Patent Application Publication 1986
Similar to PMMA, dry etching resistance is insufficient. Although polyphenyl methacrylate has improved dry etching resistance compared to PMMA, its sensitivity is as low as that of PMMA. Also,
Research and development of positive resists with excellent dry etching resistance and high sensitivity has been actively conducted, but resists with sufficient performance, such as poor resolution, have not yet been developed.

[Problem to be solved by the invention] In recent years, various polymers containing halogens such as fluorine have been studied, and are being used for various purposes by taking advantage of their properties, especially those with high sensitivity to electron beams or X-rays. Therefore,
Note [1] is collected as a resist shrine. however,
Despite the recent trend toward miniaturization and the shift to dry processes, resists still have the drawback of insufficient dry etching resistance.

Furthermore, the current situation is that positive resists having dry etching resistance lack sensitivity, and that attempts to achieve high sensitivity result in poor resolution.

The present invention has been made from the above-mentioned viewpoint, and its object is to obtain a positive type dimethacrylate that has particularly improved dry etching resistance, high sensitivity, and high resolution.

[Means for Solving the Problems] Based on this background, the present inventors have conducted extensive research and have completed the present invention.

That is, the present invention is based on the general formula (wherein, R, and R2 represent hydrogen or a fluorine-substituted methyl group, and are not hydrogen at the same time; Y and ~Y5 represent hydrogen or fluorine; R1 represents a fluorine-substituted alkyl group; m
, n represents a positive integer, and n/m is 1 or less. )
Provided is a /X halogen-containing polyacrylic ester derivative represented by / It is something to do.

The halogen-containing polyacrylic ester derivative of the present invention is a copolymer of an acrylic ester containing chlorine at the α-position, a fluorine atom and a benzene ring in the ester moiety, and an acrylic ester whose ester moiety is a fluorine-substituted alkyl group. It is a combination.

The copolymer of the present invention can be produced by using the corresponding monomers by known methods such as bulk polymerization, solution polymerization, emulsion polymerization, etc., and the degree of polymerization thereof is from 20 to 20,000. As the polymerization initiator, hydrogen peroxide, peroxides such as benzoyl peroxide, azo compounds such as azobisisobutyronitrile, persulfates such as potassium persulfate, etc. can be used.

Examples of α-chloroacrylic acid ester monomers include α
-1-phenyl-chloroacrylate-2゜2.2-)lifluoroethyl ester, α-chloroacrylic acid 2-phenyl-hexafluoroisopropyl ester, α-chloroacrylate 1-pentafluorophenyl-2,2,2
-1 Lifluoroethyl ester, α-chloroacrylic acid 2-pentafluorophenyl-hexafluoroisopropyl ester, α-chloroacrylic acid 1-p-fluorophenyl-2.2.2-1 Lifluoroethyl ester,
Examples include α-chloroacrylic acid 2-p-fluorophenyl-hexafluoroisopropyl ester.

Examples of comonomers include α-chloroacrylic acid trifluoroethyl ester, α-chloroacrylic acid hexafluoroisopropyl ester, α-chloroacrylic acid tetrafluoropropyl ester, α-chloroacrylic acid hexafluorobutyl ester, etc. be able to.

The α-chloroacrylic acid ester monomer can be produced, for example, by the following method.

First, by reacting acrylic acid chloride with the alcohol or its alkali salt corresponding to the ester to be prepared,
Synthesize acrylic acid ester, then react with chlorine gas to form α,β-dichloropropionic acid ester, add equimolar amount of quinoline or pyridine, and perform vacuum distillation or reflux followed by filtration, extraction, and column separation. Accordingly, the desired α-chloroacrylic acid ester monomer can be synthesized.

[Function] The halogen-containing polyacrylic acid ester derivative of the present invention can be used as a resist material to form a resist pattern by electron beam drawing, etc., and has excellent radiation sensitivity, resolution, and dry etching resistance. ing.

There are no particular limitations on how to use the halogen-containing polyacrylic acid ester derivative of the present invention to form a resist pattern by electron beam drawing or the like, and any conventional method can be used.

When using the halogen-containing polyacrylic ester derivative of the present invention as a resist coating, the coating solvent is not particularly limited as long as it can dissolve the polymer and form a uniform film, such as xylene, toluene, benzene, etc. , tetrahydrofuran, ethylene glycol monoethyl ether acetate-1., ethylene glycol monomethyl ether acetate-1., and the like. The amount used is a conventional amount, for example, about 5 to about 30% of the halogen-containing polyacrylic acid nyster of the present invention, about 95 to about 70% of the solvent.
That's about it.

As the developer, for example, a mixed solvent of the above-mentioned solvents and alcohol, or a mixed solvent of ester or ketone solvent and alcohol can be used. Other methods such as coating, pre-baking, exposure, and development can be carried out by conventional methods.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

In addition, the electron beam sensitivity test in Examples was conducted by the following method.

A solution of the polymer ethylene glycol monoethyl ether acetate-1 or 1,4-bis(trifluoromethyl)benzene was spin-coded onto a silicon wafer, and 0.
A coating film of 5 μm was obtained. After pre-baking at 200°C for 30 minutes, an accelerating voltage of 20 KV was applied to the desired part of the coating.
The electron beam was irradiated with various doses. Then, 24℃
The irradiated areas were selectively removed by immersion development. Sensitivity and resolution were evaluated from a sensitivity curve diagram depicting the relationship between dose and residual film thickness after development.

Here, the sensitivity (hereinafter referred to as S value) is indicated by the value of the irradiation amount at which the remaining film thickness becomes zero. Also, solution] elephant degree (hereinafter,
The γ value) is expressed as a pair at the point where the film thickness begins to decrease on the tangent line corresponding to the S value of the sensitivity curve, and the image quality of large culm debris is high.

[For details, refer to [Cutting-edge application technology of fluorine compounds] CMC, published April 24, 1980, pages 139-140] The dry etching resistance test was conducted using dry etching equipment D.
Using EM-451 type (manufactured by Nikkei Anelva), CF4
Resistance to reactive sputtering by gas was observed.

Example 1 18.8 g of α-chloroacrylic acid 2-phenyl-hexafluoroisopropyl ester, 6 g of α-chloroacrylic acid 2-phenyl-hexafluoroisopropyl ester, 1°1.1- of azobisisobutyronitrile 1-lichloroethane solution 5.0 mA (azobisisobutyronitrile 0
．． 2wt%) and 1.1. >Trichloroethane 31
．． 5 mj2 was placed in a flask and vacuum degassed according to a conventional method. After stirring the flask at 70° C. for 7 hours, the reaction product was poured into n-hexane to precipitate the polymer, filtered and dried to obtain 2-phenyl-α-chloroacrylate.
A hexafluoroisopropyl/α-chloroacrylic acid hexafluoroisopropyl copolymer was obtained. As a result of GPC measurement, the weight average molecular weight is 3-I in terms of polystyrene.
It was XIO5. Next, an electron beam sensitivity test was conducted, and when development was performed for 3 minutes using methyl isobutyl ketone/isopropyl alcohol as the developer, the S value and γ value were 4 μC/c+ff and 2.8, respectively. A pattern was formed. Also, 0.75μ
An m-line and space pattern could be resolved, and its shape was excellent.

Further, when a dry etching resistance test against reactive ion etching using CF4 gas was conducted, the etching rate was 1900 people/min. For comparison, the etching rate of polymethyl methacrylate was measured and was 2200 people/min.

Example 2 18.8 g of α-chloroacrylic acid 2-phenyl-hexafluoroisopropyl ester, 1°2 g of α-chloroacrylic acid trifluoroethyl ester, 1 solution of azobisisobutyronitrile in 1.1.1-trichloroethane? &5
．． 0mAC azobisisobutyronitrile 0.2wt%
) and 1,1°1-trichloroethane31. ! 5m
A was placed in a flask and 1' of the copolymer was added according to Example 1.
,)Ta. The weight average molecular weight was 3,3 x 105.

Next, an electron beam sensitivity test was conducted, and when development was performed for 3 minutes using methyl isobutyl ketone/isopropyl alcohol as the developer, the S value and γ value were each 4μ.
A positive type pattern was formed with C/at, 3.5. Moreover, the pattern shape of 0.75 μm line and space was excellent.

Example 3 23.9 g of α-chloroacrylic acid 2-pentafluorophenyl hexafluoroisopropyl ester, 1.2 g of α-chloroacrylic acid trifluoroethyl ester, 1.1.1-)lichloroethane of azobisisobutyronitrile Solution 5. Omj (0..2w azobisisobutyronitrile
t%) and 1,1.1-trichloroethane 35.0
d was placed in a flask, and a copolymer was obtained according to Example 1. The weight average molecular weight was 3.5 x 105.

Next, an electron beam sensitivity test was conducted using isopropyl acetate/isopropyl alcohol as the developer.
After developing for a minute, the S value and γ value were each 4μC/c.
A positive type pattern of J, 4.2 was formed.

Also, 0.75 μm Ra-12= In-and-space pattern geometry was excellent.

[Effects of the Invention] The halogen-containing polyacrylic ester derivative of the present invention is an acrylic ester polymer containing chlorine at the α-position, a fluorine atom, and a benzene ring in the ester moiety, and is resistant to electron beams, deep ultraviolet rays, or X-rays. Irradiation with such radiation causes a main chain collapse reaction, and the irradiated area greatly improves its solubility in solvents compared to the non-irradiated area.

Although polymethyl methacrylate and polyphenyl methacrylate also undergo main chain collapse due to these radiations, the halogen-containing polyacrylate ester derivative of the present invention
Since halogen is contained in the α-position and the ester moiety, a disintegration reaction is likely to occur, resulting in an increase in sensitivity. Further, the halogen-containing polyacrylic acid ester derivative of the present invention has excellent dry etching resistance because it contains a benzene ring.

Claims (3)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R_1 and R_2 represent hydrogen or a fluorine-substituted methyl group, and cannot be hydrogen at the same time. Y_1 to Y_5 represent hydrogen or fluorine. R_1 is a fluorine-substituted methyl group. (represents an alkyl group, m and n represent positive integers, and n/m is 1 or less.) A halogen-containing polyacrylic acid ester derivative. (2) A resist material composition comprising the halogen-containing polyacrylic acid ester derivative according to claim (1). (3) A method for forming a resist pattern, characterized in that the halogen-containing polyacrylic acid ester derivative according to claim (1) is used as a resist material.