JPS6093429A - Positive type ionization radiation resist composition - Google Patents

Abstract

PURPOSE:To enhance dry etching resistance by incorporating a specified org. sulfonate copolymer. CONSTITUTION:A resist compsn. contains a copolymer of alpha-methylstyrensulfonic acid and alpha-methylstyrenesulfonic acid ester having an average mol.wt. of 1,000- 50,000 and represented by general molecular structural formula I in which R is a group of structural formula II; X is methyl, ethyl, hydroxymethyl, or hydroxyetyl; and m/(m+n) is 0.2-1.0. As a result, a resist compsn. high in sensitivity and excellent in dry etching resistance can be obtained without impairing resolution, transmittance, and contrast.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a positive ionizing radiation resist, and more specifically to a positive resist with high dry etching resistance in short-wavelength ionizing radiation, particularly electron beam exposure technology. Regarding type electron beam resist.

0) Background of the Technology Generally, a photosensitive resin called a resist is used to form a pattern on the surface of a semiconductor.

This resist is divided into two types: those exposed to light disappear during development and those that remain; the former is called a positive type, and the latter is called a negative type. In recent years, in order to obtain fine patterns that determine the accuracy of ICs, LSIs, etc., the film formed on the resist has to be thin and uniform, without pinholes, and on the substrate (Si).
, 5in2, etc.), good acid resistance, and high sensitivity to ultraviolet rays.

Furthermore, as radiation for exposure, short wavelength far ultraviolet, electron beam, X-ray, ion beam, etc. are used. Recently, IBM has used PM as a resist in electron beam exposure.
After developing M (polymethyl methacrylate),
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We are developing a MOS LSI with a memory circuit of 2,000 darts and a storage capacity of 128 bits.

ri) Conventional technology and problems In general, the conditions that a resist should have are: high resolution,
High sensitivity, (2) transparency, (3) high contrast, (4)
These include Zorazya resistance, adhesion, chemical resistance, and ion resistance. Good contrast, transparency, and resolution means that thicker lenants can have a larger shape ratio, and furthermore, the yield can be improved by reducing pinholes.

Expanded polymethyl methacrylate as a conventional positive resist
) (PMlilA) and olefin-sulfone resins such as polybutene-1-sulfone (pus). PMMA has the best resolution, transparency, and contrast, and has a broad photosensitive region with a peak wavelength of 220 nm.Although it is not sensitive to long wavelengths of 260 nm or more, it is capable of resolution of 0.2 μm or less. Adashi,
It is possible to transfer a resist with a thickness of 2 to 3 μm. However, PRIMA has low sensitivity, plasma resistance and/or
There is a problem that the dry etching resistance after forming the 4' turn is poor.

On the other hand, PB8 has a single sensitivity at a wavelength of 184 nm, and this sensitivity is two orders of magnitude higher than that of PMMA. However, its resolution is extremely poor and its dry etching resistance is low.

In this way, conventional positive resists have a common characteristic of A? There is a drawback that the dry etching resistance after the turn is formed is poor.

B) Object of the Invention The object of the present invention is to solve the above-mentioned problems and provide a positive type electron beam resist with high dry etching resistance.

(B) Structure of the Invention The present invention provides that when polyα-methylstyrenesulfonyl chloride is reacted with phenol, cresol, or 4-hydroxypensiphenone, the synthesized sulfonic acid ester polymer becomes alkaline by electron beam irradiation. Based on this knowledge, we have completed the resist composition of the present invention, which is highly sensitive, has excellent dryer resistance, and has excellent anti-chewing properties without impairing resolution, transparency, or contrast. be.

That is, the present invention has an average molecular weight of i, o o o ~ 50,000, and has a general molecular structural formula (■):
X is 10M, -C2H5, -0-CR2 or -0-
C2H5, □ is 0.2 to 1.01, preferably 0.
Provided is a positive electron beam Renost composition containing an α-methylstyrene sulfonic acid-α-methylstyrene sulfonic acid ester copolymer having a molecular structure shown in the following formula (5 to m1n 1.0).

In the copolymer of formula (1) in the present invention; T; is 0
．． It needs to be in the range of 2 to 1.0.

When □<0.2, the film thickness during development becomes severe. There is a tendency for the contrast of the 4th turn to decrease.

Using the resist composition of the present invention, in order to form a mother turn, in FIG.
(At, Si, SiO2, etc.), (b) electron beam irradiation is applied to this resist film 1 according to a predetermined pattern, thereby the exposed portion of the resist film undergoes a change, (C) By development, the exposed portion is easily dissolved in the alkaline developer 3, and (d) a pattern is formed in the resist film 1. After the developed resist film is expanded, it is subjected to dry etching.

(E) Example 5 of the invention 10 g of Yupoly α-methylstyrene (Mw #1000)
and chlorosulfonic acid 50II was stirred at room temperature for 4 hours to synthesize polyα-methylstyrenesulfonyl chloride. Next, a mixture of 6 g of this polyα-methylstyrenesulfonyl chloride and 10 g of phenol was added at 50 g.
9 was dissolved in tetrahydrofuran, and pyridine 10.9 was added dropwise to this solution over 30 minutes while stirring the solution at 40°C.

After the mixture was stirred for 4 hours, the reaction solution was poured into a large amount of cyclohexane, and the resin produced was precipitated and separated. This resin was mixed with water and left overnight to convert the chlorosulfonic acid residue into sulfonic acid. It was dissolved in oxane and freeze-dried.

Example 2 The resin obtained in Example 1 was dissolved in cyclohexanone to prepare a resist solution. This resist solution was spin-coded onto a silicon substrate and then baked at 80° C. for 20 minutes in a nitrogen stream to form a resist IIIE. One electron is applied to this resist film at an accelerating voltage of 20 kV according to a predetermined pattern.
iiIj! irradiated with MF-31 manufactured by 7 Tsuzore
Developing was performed using 2 developer.

After developing for 120 seconds, the film was rinsed with ion-exchanged water.

The sensitivity of the resist film at this time was 10 μC/an2. Further, this resist film was put into a parallel plate type dry etching device, and C3F8 gas (gas pressure 0.06 Torr1
When etching was performed with an applied force of 0.33 W/cm'', the etching speed was 172, which was good for PMMA.

Example 3 Polyα-methylstyrenesulfonyl chloride was synthesized in the same manner as in Example 1. This polyα-methylstyrenesulfonyl chloride 61:, 4-hydroxybenzophenone 1
011 in 50.9 g of tetrahydrofuran, a part of the sulfonyl chloride group was modified to sulfonic acid 4-hydrogysipe/siphenon ester in the same manner as in Example 1, and the resulting resin was washed to remove the remaining chlorosulfonyl chloride/acid group. was converted into a sulfonic acid group, and the resulting resin was dried.

A resist film was formed in the same manner as in Example 2, and subjected to electron beam exposure and development. Development time is 150 seconds, sensitivity is 15μC
/an'' (E) Effects of the Invention According to the present invention, a d?-type electron beam resist with high dry etching resistance can be provided.

[Brief explanation of the drawing]

In FIG. 1, a resist film is formed using the positive resist of the present invention, and this is subjected to electron beam irradiation and development with a developer solution. A flow diagram illustrating the process of forming turns. 1...Resist, 2...Substrate, 3...Developer first
times

Claims (1)

[Claims] has an average molecular weight of 1.000 to 50,000, and has a general molecular structure (I): a group, X is -CH,, -C2H5, -0-CH,,
A positive type containing an α-methylstyrenesulfonic acid-α-methylstyrenesulfonic acid ester polymer having a molecular structure represented by m+n Ionizing radiation resist composition.