JPS62134644A - Positive type resist composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION C Summary] An ionizing radiation resist with improved sensitivity, comprising methacrylic acid ester and trimethylsilylmethylene methacrylate as main components, and methacrylic acid or a copolymer of the methacrylic acid and methacrylic acid chloride.

[Industrial application field]

The present invention relates to a positive resist for ionizing radiation with improved sensitivity.

2. Description of the Related Art Information processing technology has made remarkable progress in order to process large amounts of information at high speed, and the electronic circuit elements used therein are becoming increasingly smaller.

Here, thin film formation technology and photolithography (photolithography or electron beam lithography) are often used to form fine patterns.

That is, after forming a thin film such as a conductive layer or an insulating layer on the substrate to be processed by a physical method such as vacuum evaporation method or sputtering method, or a chemical method such as chemical vapor deposition method, a thin film such as a conductive layer or an insulating layer is formed on the substrate to be processed. The resist is coated using the method described above, and then UV rays are irradiated through a mask, or ionizing radiation such as electron beams or X-rays is irradiated to produce intense light, causing a difference in the solubility of the exposed areas in the developing solution. A resist pattern is formed using chemical etching or dry etching to form a fine pattern on a substrate to be processed or a thin film formed thereon.

In the conventional pattern forming method using ultraviolet light exposure, the formation of fine patterns is limited by the wavelength.
It is limited to patterns with line widths of μm or more, and it is difficult to form fine patterns smaller than this.

On the other hand, since the wavelength of ionizing radiation such as electron beams is much shorter than that of ultraviolet rays, it is possible to form fine patterns of less than 1 μm. Therefore, in many cases, ionizing radiation is used to form semiconductor devices such as LSI and νLSI. In particular, pattern formation is performed using electron beams.

The present invention relates to improvements in positive resists used for this purpose.

[Conventional technology]

Conventional positive resists for ionizing radiation include acrylic resins such as polymethyl methacrylate (abbreviated as PMMA),
Olefin sulfone resins such as polybutene sulfone (abbreviated as PBS) are used as the main component of resists.

However, although acrylic resist has high resolution, its sensitivity is only 50
~70 μC/cm 2 is not satisfactory.

On the other hand, PBS has the problem of high sensitivity but low resolution and dry etching resistance.

As described above, a positive resist that satisfies all three conditions of sensitivity, resolution, and dry etching resistance has not yet been put into practical use.

[Problem that the invention seeks to solve]

As described above, there is currently no positive resist that satisfies all three conditions of sensitivity, resolution, and dry etching resistance.

Therefore, the problem is how to improve the sensitivity of acrylic resists, which have excellent resolution.

[Means for solving problems]

The above object consists of a copolymer of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate, or a mixture of said polymer and a copolymer of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate and methacrylic acid chloride, This can be achieved with a positive resist composition in which monomers are copolymerized randomly into polymer chains.

[Effect]

The present invention is to develop a highly sensitive positive resist by copolymerizing methacrylic acid ester and trimethylsilylmethylene methacrylate, which are the main components of an acrylic positive resist.

However, when l-limethylsilylmethylene methacrylate is copolymerized, the solubility of the resin increases and the sensitivity increases to about 7 μC/c.
m2, but at the same time it becomes easier to swell.

Therefore, methacrylic acid, methacrylic acid chloride, or both are further added and copolymerized to create a resist, and this resist is applied to the substrate to be processed and then heated to form a crosslinked resist. This prevents swelling and improves sensitivity. This further improves resolution.

Which combination to adopt here is determined by the sensitivity required by the user, and various configurations are possible.

Figure 1 shows the basic composition of methacrylic acid ester.

Figure 2 shows the molecular structure of a copolymer consisting of methacrylic acid and trimethylsilylmethylene methacrylate, and Figure 2 shows the molecular structure of a copolymer consisting of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate, and methacrylic acid chloride. It shows the molecular structure formula.

Here, R constituting the methacrylic acid ester is a methyl group,
It consists of an alkyl group such as an ethyl group, a propyl group, a butyl group, and a phenyl group, and between Tn, β, and n, which indicate the composition ratio of the copolymer, as shown at the bottom of Figures 1 and 2. There is a limit.

That is, as the composition ratio of trimethylsilylmethylene methacrylate increases, the sensitivity increases, but the resolution tends to decrease, and therefore the copolymerization ratio is limited to 1 to 50 mol%.

In addition, the amount of methacrylic acid added may be within a range sufficient to crosslink and cure the resin, but if the copolymerization ratio becomes high, problems will arise in terms of solubility and film forming properties, so the copolymerization ratio should be 0 to 2.
Limited to 0 mol%.

In addition, the addition of methacrylic acid chloride may be in a range sufficient to crosslink and cure the resin, but if the copolymerization ratio is high, gelation tends to occur during polymerization, and there is also the problem that chlorine atoms cause corrosion of device wiring. .

Therefore, the copolymerization ratio is limited to 1 to 10 mol%.

Next, the configuration of the present invention will be specifically explained as follows.

■ A resist made by copolymerizing methacrylic acid ester, methacrylic acid, and trimethylsilylmethylene methacrylate. (Corresponding to molecular structural formula I) ■ A copolymer consisting of methacrylic acid ester, methacrylic acid, and trimethylsilylmethylene methacrylate (corresponding to molecular structural formula I),
A resist made by mixing a copolymer of methacrylic acid ester, trimethylsilylmethylene methacrylate, and tutaacrylic acid chloride (corresponding to N=O in the molecular structure formula).

■ A copolymer of methacrylic acid ester, methacrylic acid, and trimethylsilylmethylene methacrylate (corresponding to molecular structure I) and a copolymer of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate, and methacrylic acid chloride (corresponding to molecular structure H) ).

〔Example〕

Example 1 (corresponding to ■ in the action column) 80 g of methyl methacrylate, 7 g of methacrylic acid.

34g of trimethylsilylmethylene methacrylate lo
ng benzene? 8, and using 0.58 n,n'-azoisobutylnitrile (abbreviated as IBN) as an initiator, 60
Copolymerization was carried out at ℃ for 30 hours.

The reaction solution was poured into cyclohexane to precipitate the resin, which was recovered, dissolved in 1,4-dioxane, and freeze-dried to produce a resin.

This resin was dissolved in cyclohexanone, and silicon (Si
) onto the substrate using a spin code method, and then coat the substrate with
It was heated at 0°C for 30 minutes to cure the crosslinking.

Next, set it in an electron beam exposure device (acceleration voltage 20KV),
After being irradiated with an electron beam, the film was developed by immersing it in methyl isobutyl ketone (formerly BK) for 3 minutes, and was rinsed with cyclohexane.

The sensitivity of this resist was 10 μC/cm2.

Example 2 (Corresponding to ■ in the effect column) A resist made in the same manner as in Example 1, coated on a Si substrate and cross-linked and cured was exposed to X-rays (Mo Lα wavelength 5°, 4 people).
was irradiated, and then development and rinsing was performed in the same manner as in Example 1.

The sensitivity of this resist was 200 mJ/cm2.

Example 3 (Corresponding to ■ in the action column) Phenyl methacrylate 130g, methacrylic acid 5g+
40 g of trimethylsilylmethylene methacrylate was dissolved in 100 g of benzene; a resin was synthesized in the same manner as in Example 1, and then dissolved in cyclohexanone to prepare a resist solution.

After spin-coding this onto a Si5 plate, it was
It was prebaked for 1 minute to cure the crosslinking.

Then, in the same manner as in Example 1, electron beam irradiation, development and rinsing were performed.

The sensitivity of this resist was 15 μC/cm 2 .

Example 4 (corresponding to ■ in the action column) Methyl methacrylate 80g, methacrylic acid 5g.

10 34g of trimethylsilylmethylene methacrylate
A resin having the molecular structure formula I was prepared in the same manner as in Example 1 by dissolving it in 0 g of benzene.

Next, 80 g of methyl methacrylate, 34 g of trimethylsilylmethylene methacrylate, and 3 g of methacrylic acid chloride.
Dissolve g in 100 g of benzene and proceed in the same manner as in Example 1 with the molecular structure ■ However! = 0 resin, mix the former and the latter at a ratio of 1:2, and make cyclohexanone? I solved 8 and got the Registon skin.

This resist solution was spin-coded in the same manner as in Example 1, and after perihaking at 200° C. for 30 minutes, electron beam exposure was performed.

The pestilence of this resist was 12 μC/cm 2 .

Example 5 (Corresponding to ■ in the Effect column) A resin was prepared by copolymerizing methyl methacrylate, methacrylic acid, and trimethylsilylmethylene methacrylate in the same manner as in Example 4, and then 80 g of methyl methacrylate was added.
A resin was prepared in the same manner as in Example 1 by dissolving 4.5 g of methacrylic acid, 34 g of trimethylsilylmethylene methacrylate, and 0.5 g of methacrylic acid chloride in ioog of benzene.

These two resins were mixed in an equal ratio and dissolved in cyclohexanone to prepare a resist solution.

This resist solution was spin-coded in the same manner as in Example 1, peribaked at 200° C. for 30 minutes, and then subjected to electron beam exposure.

The pestilence of this resist was 8 μC/cm2.

Comparative Example 1 90 g of methyl methacrylate, 17 g of lymethylsilyl methylene methacrylate were dissolved in 100 g of benzene,
A resin was made in the same manner as in Example 1, and this resin was sifted to obtain J
A resist solution was prepared by dissolving it in hexanone, and this resist solution was spin-coded in the same manner as in Example 1.
After peribaking at C for 30 minutes, electron beam exposure was performed.

The pestilence of this resist was 30 μC/cm 2 .

〔Effect of the invention〕

As described above, by applying the present invention, the performance of conventional acrylic resists can be improved by 2 to 5 times, and as a result, the throughput during electron beam lithography can be greatly improved.

[Brief explanation of drawings]

Figure 1 shows the molecular structure formula (1), Figure 2 shows the molecular structure formula (II), It is. Molecular structural formula (1) Molecular structural formula (II) Figure 2 C-H. ] Yam :H8 ■ 3i(CHsh Base, C, H? , ■ base ) CI dawn :Ht 3i(CHs)s group, C4H4, <D group

Claims (1)

[Claims] It consists of a copolymer of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate, or a mixture of this polymer and a copolymer of methacrylic acid ester, methacrylic acid, trimethylsilylmethylene methacrylate, and methacrylic acid chloride, and each of the above monomers forms a polymer chain. A positive resist composition characterized by randomly copolymerizing therein.