JPH0450946A - Radiation resist and pattern forming method - Google Patents

Abstract

PURPOSE:To obtain a resist small in absorption in the wavelength region to be used and superior in resolution by adding a substance producing a proton acid by irradiation with a light or radiation to a specified azalactone polymer or polymer. CONSTITUTION:The polymer or copolymer of the azalactone compound represented by formula I contains the substance to be allowed to produce a proton acid by irradiation with light or radiation. In formula I, each of R1-R3 is H, alkyl, or aryl. The polymer of azalactone is superior in transparency in the far ultraviolet region of <=250 nm, thus permitting the obtained resist to be high in sensitivity and resolution.

Description

[Detailed Description of the Invention] [Summary] Regarding radiation resists, with the aim of commercializing resists that have low absorption in the wavelength range used and excellent resolution, we have developed an azalactone polymer or A radiation resist is formed by adding a substance that generates a protonic acid upon irradiation with light or radiation to the azalactone copolymer. R1 CH, -C where R1R1+Rff is hydrogen (H), an alkyl group, or an aromatic hydrocarbon group.

[Industrial application field]

The present invention relates to a radiation resist and a pattern forming method thereof.

In response to the increase in the capacity of information processing equipment, the semiconductor devices that make up the main body of these equipment have become more integrated, such as LSI and VLSI.
has been put into practical use, and this integration is progressing more and more.

As integration is being achieved through miniaturization of unit elements, the wiring pattern width is becoming smaller and smaller, with the minimum pattern width reaching sub-micron. ) is also limited by wavelength, so far ultraviolet light is used rather than ultraviolet light.
Electron beams and X-rays are becoming shorter in wavelength, and along with this, there is a demand for resist materials that are suitable for these types of radiation.

[Conventional technology]

Many resists based on phenolic resins have been developed that use ultraviolet light as a light source.

For example, the product name AZ series (Shisoplay@) and the product name 0FPR (Tokyo Ohka@) correspond to this.

However, when these resists are used in the deep UV region,
Due to the large absorption, sufficient resist performance could not be obtained.

On the other hand, the material represented by the structural formula (1) is used as a polyfunctional monomer for various purposes such as printing, and the polymer has excellent transparency in the deep ultraviolet region.

However, buttering with this material was difficult.

[Problem to be solved by the invention]

Conventionally used ultraviolet resists have low transparency in the deep ultraviolet region and do not exhibit sufficient effects.

On the other hand, although azalactone polymer has excellent transparency in the deep ultraviolet region, it is difficult to use it as a resist material for pattern formation.

Therefore, the challenge is to impart photosensitivity to this polymer and use it as a radiation resist.

[Means to solve the problem]

The above problem is achieved by constructing an ionizing radiation resist characterized by adding a substance that generates protonic acid upon irradiation with light or ionizing radiation to a polymer of azalactone or a copolymer of this azalactone represented by the following structural formula. This can be solved by

R plate (:1z=( Here, RI+R1+R3 is either hydrogen (■), an alkyl group, or an aromatic hydrocarbon group.

[Effect]

FIG. 1 shows the wavelength dependence of light transmittance for an azalactone polymer, which shows excellent transparency even in the deep ultraviolet region with a wavelength of 250 nm or less.

On the other hand, a method in which an acid generator that generates protonic acid (H) upon irradiation with light is used as a reaction initiator is known as a method for obtaining patterns with excellent sensitivity and resolution.

The present invention makes it possible to put into practical use a resist with high sensitivity and excellent resolution by adding an acid generator that generates protonic acid when irradiated with radiation to a polymer or copolymer that has low absorption even in the deep ultraviolet region. It is something that becomes.

Figure 2 shows the infrared absorption spectrum of the resist before exposure and the 20-minute heating at 110°C after exposure.
Absorption spectra were taken for those subjected to after-baking) and the two were compared.

From the same figure, it can be seen that the absorption spectrum changes significantly, but this is due to the structural change caused by the presence of a substance that generates protonic acids, especially in the wavenumber range of 2500 to 350.
The absorption is large in the 0 region, and this structural change is thought to be the cause of the change to alkali-solubility.

In the present invention, a resist is prepared by adding a substance that generates protonic acid when irradiated with radiation to a polymer or copolymer of azalactone, and this resist is applied onto a substrate to be processed and exposed to radiation in the same manner as in the past. After that, an after-bake is performed to cause a structural change in the polymer or copolymer in the exposed area, thereby making it possible to perform alkali development.

When such a resist is used, absorption is small even in the far ultraviolet region, so a resist pattern with high sensitivity and excellent resolution can be obtained.

〔Example〕

Example 1: After adding azoisobutyronitrile (abbreviated as AIBN) as a reaction initiator to 2-vinyl-4-4-dimethylazalactone and heating it at 80°C, the mixture became viscous after about 15 minutes. became.

This was purified by dissolving it in tetrahydrofuran (abbreviated as THF) and precipitating it with hexane.

As a result, a polymer with a molecular weight of 300,000 and a dispersity of 4.00 was obtained.
After adding 20% of donium salt to make a cyclohexanone solution, it was spin-coded onto a Si substrate to a thickness of 0.5 μI.

After that, after pre-baking at 90℃ for 20 minutes and drying,
Exposure was performed using an e-Hg lamp for 10 seconds.

Furthermore, as a result of developing for 20 seconds with pumped water that had been pre-baked at 110° C. for 20 minutes, it was possible to resolve 0.5 μι lines and spaces.

Example 2: In Example 1, an alkaline aqueous solution (diluted tetramethylammonium hydroxide abbreviation T) was used as the developer.
MAH) for 5 seconds, it was possible to resolve lines and spaces of 0.7 μm.

Example 3: As a result of developing for 30 seconds using cyclohexanone as the developer in Example 1, 0.5μ■ line and...
I was able to obtain a negative pattern of space.

Comparative Example 1: Similar evaluation was performed in Example 1 using a resist made only of a polymer without using an acid generator, but no pattern could be formed.

Example 4: Adamantyl methacrylate and 2-vinyl-4-4 dimethylazalactone were charged into a reaction vessel, and after polymerization using AIBN as an initiator, tetrahydrofuran (abbreviated as TH
F) /As a result of purification using hexane, the composition ratio was 1:
A copolymer of No. 1 could be obtained.

A cyclohexanone solution was prepared by adding 20% of an iodonium salt having the structural formula shown in formula (2) as an acid generator to this polymer, followed by exposure and after-baking in the same manner as in Example 1, and development using a diluted TMAR aqueous solution. did.

As a result, it was possible to resolve 0.6 μm line and space.

Example 5: Similar results could be obtained when a sulfonium salt represented by the structural formula (3) was used in place of the iodonium salt as the acid generator in Example 1.

〔Effect of the invention〕

As described above, by carrying out the present invention, it becomes possible to efficiently obtain a submicron pattern when a fine resist pattern is formed using photolithography using radiation such as deep ultraviolet rays as a light source.

[Brief explanation of drawings]

Figure 1 shows the ultraviolet spectrum of the azalactone polymer, Figure 2 shows the infrared absorption spectrum, and Figure 3 shows the structural formulas of the iodonium salt and sulfonium salt. Ultraviolet spectrum part of asalactone polymer 1 Figure 2 Number (CTF') Red Tato+1rJ3. Yield spectrum Figure 2

Claims (2)

[Claims] (1) A radiation resist comprising a polymer of azalactone or a copolymer of azalactone represented by the following structural formula, and a substance that generates a protonic acid upon irradiation with light or radiation. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) Here, R_1, R_2, and R_3 are hydrogen (H), an alkyl group, or an aromatic hydrocarbon group. (2) A method for forming a resist pattern, which comprises applying the resist-containing material according to claim 1 onto a substrate to be processed, pre-baking it, selectively exposing it to radiation, and developing it after after-baking.