JPS60252348A - Formation of pattern - Google Patents

Abstract

PURPOSE:To improve the resolution of a pattern, sensitivity, heat resistance, and plasma resistance by using a combination of specified two kinds of terpolymers. CONSTITUTION:A positive type resist pattern is formed by using a resist material consisting of a mixture in the combination of a terpolymer (A) of alpha-trifluoromethyl methacrylate, methyl methacrylate, and methacrylic acid, and a terpolymer (B) of alpha-trifluoromethyl methacrylate, methyl methacrylate, and methacryloyl chloride, preferably, in a (A)/(B) mixing ratio of 1:1 and irradiating said material with electron beams. A substrate is coated with a soln. having said combination, hard-baked to cross-link it, and patternwise exposed to electron beams and developed, thus permitting a sharp positive type resist pattern superior in sensitivity and resolution, and said pattern is prevented from deformation of the pattern and improved in heat and plasma resistances by said hard-baking treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming four turns. More particularly, the present invention relates to a method of irradiating a thermally crosslinked decomposable resist material with high energy radiation, such as an electron beam, to form positive resist turns after development. This /4' turn forming method can be advantageously used in microfabrication fO process for semiconductor device manufacturing.

BACKGROUND OF THE INVENTION Many positive resist materials for electron beam exposure are in practical use. Many of these resist materials are historically old polymethyl methacrylate, which is characterized by excellent resolution. However, this polymethyl methacrylate has poor sensitivity, and is also poor in heat resistance and plasma resistance. Therefore, when polymethyl methacrylate is used to perform tectonic formation, deformation and decomposition of the resist pattern often occur in one lasma etching step after pattern formation, thus making it difficult to achieve satisfactory resist function. I can't.

In order to avoid the disadvantages specific to polymethyl methacrylate as described above, the present inventors developed a thermally crosslinked and decomposed resist material of polymethyl methacrylate, poly(methyl methacrylate-co-methacrylic acid) represented by the following formula: A resist material consisting of a mixture of poly(methyl methacrylate-co-methacrylic acid chloride) represented by the following formula has been developed and is widely used. This type of resist material has excellent heat resistance and plasma resistance because it is a thermally crosslinked and decomposed type, and can easily increase apparent sensitivity because a strong developer can be used. It has enhanced resolution by taking advantage of the properties of polymethyl methacrylate.

Problems to be Solved by the Invention In view of the above-mentioned drawbacks of the conventional technology, the present invention aims to improve the apparent sensitivity as in the pyrolytic crosslinking resist materials widely used by the present inventors. Provided is a method that solves the problem of actually increasing sensitivity without the need for a photoresist, thereby making it possible to form a resist film having high resolution, high sensitivity, and excellent heat resistance and plasma resistance. This is what I am trying to do.

Means for Solving the Problems As a result of research to solve the above-mentioned problems, the present inventors have found that
α-Trifluoromethyl methacrylate has a sensitivity increasing function, and the copolymer expressed by the following formula obtained by copolymerizing methyl methacrylate with α-trifluoromethyl methacrylate is expected to increase sensitivity by one order of magnitude. Obtained: For example, when r / s ratio = 3 near, the sensitivity of polymethyl methacrylate. = 1x 10-' High sensitivity that is one order of magnitude thicker than C/cd or less. = I X 10-'
C/- can be realized. Furthermore, if the ratio of α-trifluoromethyl methacrylate is increased, the t
Although it is thought that an increase in sensitivity can be expected, this is difficult from the viewpoint of collecting the copolymer, and the γ/S ratio is only 5:5 at most.

As a result of comprehensive consideration of the above findings and the characteristics of the thermally crosslinkable and decomposable mixed resist, the present inventors discovered that poly(α-trifluoromethyl methacrylate-co-methyl methacrylate), 117 is also a highly sensitive thermally crosslinkable and decomposable type resist. We succeeded in developing a positive resist material and completed the present invention.

The present invention consists of a mixture of a terpolymer matrix of α-trifluoromethyl methacrylate, methyl methacrylate and methacrylic acid with a terpolymer Φ) of α-trifluoromethyl methacrylate, methyl methacrylate and methacrylic acid chloride. It is characterized in that a positive resist pattern is formed using a resist material by electron beam irradiation.

Terpolymer (2) of α-trifluoromethyl methacrylate, methyl methacrylate and methacrylic acid used in the present invention is represented by the following formula: Polymer [F]) is represented by the following formula: These terpolymers (4) and 03) can be prepared by subjecting a monomer solution containing a 3s monomer to a polymerization reaction according to a conventional method.

The terpolymer and [F]) are preferably 1:1
It is used at a mixing ratio of However, it is of course possible to use these terpolymers at a ratio other than the above mixing ratio depending on the desired result.

The four-turn forming method according to the invention can be carried out, for example, as follows: First, the mixture of terpolymers selected as resist phase is dissolved in a suitable solvent, such as ethyl cellosolve. do. The resulting resist solution is applied onto a substrate, and the terpolymer is thermally crosslinked by node-paking at a high temperature. Next, using a commonly used electron beam (EB) exposure device, Elt light is applied to form a desired image pattern. After the exposure is completed, development is carried out with a developer such as acetone/isozorobyl alcohol (10:90 mixture). In this way,
A positive resist pattern corresponding to the image pattern is obtained.

Example The following examples further illustrate the method of the invention.

Example 1: Poly(α-trifluoromethyl methacrylate-co-methyl methacrylate-co-methacrylic acid) (X::
! / : Z == 2 : 5 : 3 ) (MW
= 100,000) and poly(α-trifluoromethyl meccrylate-co-methyl methacrylate-co-methacrylic acid chloride) (t:m:n=3=5:2) (Mw
= 150,000) was dissolved in ethyl cellosolve to obtain a 20% by weight resist solution.

This resist solution is applied to a film thickness of 0.5 mm on silicone wafer.
Spin coded at 7 μm and further coded at 170 μm in nitrogen atmosphere.
Hard bake at ~180°C for 60 minutes. After completion of the hard bake, EB patterning was performed using an ordinary EB exposure apparatus at an accelerating voltage of 20 KeV. After patterning, acetone/isozorobyl alcohol (10:9)
0 mixed solution), a clear positive resist pattern was obtained. Resolution 0.7 μm t/8; Sensitivity [D. =6X10-6C/d0 When this resist pattern was further baked in a nitrogen atmosphere, no abnormality was observed in the pattern shape up to a temperature of 240°C. From this, it was clear that the resist of this agent had excellent heat resistance.

Furthermore, when glazma enotching was performed using this resist pattern as a mask, no abnormalities such as pattern deformation were observed. , the resolution, sensitivity, heat resistance, and plasma resistance of the resist pattern can all be improved. Therefore, by using the pattern forming method according to the present invention, more effective microfabrication can be achieved in the manufacture of semiconductor devices.

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. α-trifluoromethyl methacrylate. Terpolymer of methyl methacrylate and methacrylic acid and α-trifluoromethyl methacrylate. 1. A pattern forming method, comprising forming a box-shaped resist pattern by electron beam irradiation using a resist material made of a mixture of methyl methacrylate and a terpolymer of methacrylic acid chloride. 2. The mixing ratio of the terpolymer mixture is 1:1.
A pattern forming method according to claim 1.