JPH0223354A - Pattern forming method - Google Patents

Abstract

PURPOSE:To improve sensitivity, definition and etching resistance by using a mixture composed of a specific polymer or the copolymer thereof and a compd. which forms protonic acid by irradiation of radiations as a radiation sensitive resist material of a positive type. CONSTITUTION:The mixture composed of the polymer of any of formulas I-III or the copolymer thereof and the compd. which forms the protonic acid by the irradiation of radiations is used. In formula I-III, X denotes -H, -OR2, -CO2R3 (R2, R3 denotes N or alkyl group), alkyl group, nitrile group, etc,; Y denotes -CO-, -O-, alkylene group or phenylene group; Z denotes an alkylene group or phenylene group; R denotes -H, -SI(CH3)3 or alkyl group. The high sensitivity and high definition are obtd. in this way and the dry etching resistance is improved as well. The finer semiconductor having the higher scale of integration is obtd. in this way.

Description

[Detailed Description of the Invention] [Summary] Regarding a pattern forming method, particularly a pattern forming method using a positive radiation-sensitive resist, a resist pattern that exhibits high sensitivity and high resolution and has excellent dry etching resistance is disclosed. For the purpose of providing a method for forming general formula (I), (0), (I) CI□ Yo-1,■)9. -6,3. -6゜2I?
3 (R,, R1+ i?3 is -H or alkyl group) halogen alkyl group or nitrile group, Y is -CO--
O-, an alkylene group or a phenylene group, Z represents an alkylene group or a phenylene group, and R represents 10-Si (CHz) i or an alkyl group.

Further, Y and Z may be omitted. ) or a copolymer thereof and a compound that generates a protonic acid upon irradiation with radiation is used in a positive radiation-sensitive resist material.

[Industrial application field]

The present invention relates to a pattern forming method. More specifically, the present invention relates to a pattern forming method using a positive radiation-sensitive resist.

(Conventional technology) In recent years, in the manufacture of integrated circuits, there has been an increasing demand for higher density elements, and progress has been made to establish ultra-fine circuit pattern technology. As methods for forming patterns using high-energy radiation such as far-ultraviolet X-rays and electron beams have been developed, it is essential to develop high-performance resist materials that are sensitive to these radiations.

Furthermore, in the etching process, the wet etching method, which causes large side etching, has been replaced by a dry etching method using reactive sputtering or the like. Therefore, there is a need to provide resist materials with excellent sensitivity and dry etching resistance.

Although the decomposition efficiency is high and the sensitivity is high, the enching resistance is significantly reduced. Furthermore, although materials containing aromatic rings in their unit structures have excellent etching resistance, they have poor sensitivity to radiation and are of very low grade.

An object of the present invention is to provide a method for forming a resist pattern that exhibits high sensitivity and resolution, and also has excellent dry etching resistance.

[Problem to be solved by the invention]

Conventionally, many radiation-sensitive positive resists have been developed in which a positive pattern is obtained by lowering the molecular weight by irradiating the polymer with radiation and making use of the solubility difference due to the difference in molecular weight. A resist material with excellent resolution and dry etching resistance has not yet been developed. For example, PMIIA (methyl methacrylate polymer) is a resist material with excellent resolution, but its sensitivity to electron beams is about 100 μC/cts', which is not practical sensitivity, and its etching resistance is also insufficient. In addition, EBR-9 (East) has better radiation resistance than PjlMA (means for solving the problem).
jl.

C.B.

CH.

(In the formula, X is -n, (ri', OR2, CO!
p3 (R+, Rz, R3 is =■ or an alkyl group).

halogen, alkyl group or nitrile group, Y is -CO-
, -O-, an alkylene group or a phenylene group, Z represents an alkylene group or a phenylene group, and R represents -H, 5i(C1lz)z or an alkyl group.

Further, Y and Z may be omitted. ) or a copolymer thereof and a compound that generates a protonic acid upon radiation irradiation is used as a positive radiation-sensitive resist material. Ru.

[Function] Substances with structures represented by general formulas (+), (u), and (III) have high dry etching resistance, and in the presence of protic acids, the protic acids act as catalysts,
The trimethylsilyl group is separated to form -OH.

-IIRH, -COOH forms and becomes soluble in polar solvents such as alkaline aqueous solutions and alcohols.

Therefore, in the pattern forming method of the present invention, since a compound such as cordium salt or diazonium salt that generates a protonic acid upon radiation irradiation is added to the resist material, the polarity changes only in the radiation irradiated area. It becomes soluble in polar solvents and is developed using polar solvents. Therefore, unlike the conventional method of decomposing the main chain and utilizing the difference in dissolution rate due to a decrease in molecular weight, only the irradiated portion is dissolved in the developer, making it possible to form a resist pattern with excellent resolution. Furthermore, since the change in chemical properties described above is further promoted by baking after irradiation with radiation, sensitization is easily possible.

Therefore, it becomes possible to form a resist pattern that exhibits high sensitivity and resolution, and has excellent dry etching resistance.

[Example] An example of the pattern forming method of the present invention will be described. General formulas (I) to (I[
The substances shown in [) were polymerized in 1,4-dioxane at 80'C for 8 hours using α-trimersiloxystyrene and N-phenylmaleimide AIBN (azoisobutyronitrile) as initiators. As a result, the composition ratio was 6:4.
A copolymer of 1 weight average molecular weight -2,6R1 weight average molecular weight/number average molecular weight -1,8 was obtained. The structural formula of this copolymer is shown in the following formula (I).

HI H3CSi CI+3 This copolymer is used as a proton acid generator (◎hlL)P
He is added in an amount of 20% by weight based on the amount of polymer, and used as a cyclohexanone solution in the resist material.

The cyclohexanone solution was spread onto a Si wafer with a thickness of 1.0 μm.
After spin-coding to a thickness of It was developed with an alkaline aqueous solution for 10 minutes, and then rinsed with pure water for 30 seconds.

At this time, the sensitivity at which the residual film rate becomes 0% is 20μC/cm"
0.5 μm line and space (Line
& 5 pace).

In addition, after irradiating the electron beam, baking was performed at 130°C for 20 minutes. When developed in the same way as above with an alkaline aqueous solution containing 5% by weight of TMAH (tetramethylammonium hydroxide) for 10 minutes and rinsed with pure water for 30 seconds, the sensitivity was 8 μC/c+a'' and the resolution was the same <0.
．． 5μm line and space (Line & 5p
ace). As described above, in the present invention, sensitization is easily achieved by baking after exposure.

Next, using this resist pattern as a mask, CFa+C
When a Si wafer was etched using a parallel plate etching device using HF3 gas and the amount of film loss was measured, the amount of film loss was that of photoresist 0F, which has excellent etching resistance.
It was about the same level as PR-800.

As described above, according to the pattern forming method of the present invention, a protonic acid is generated by radiation irradiation, the trimethylsilyl group of structural formula (I) is separated, and a polar group of -OR is generated, so that only the exposed portion becomes a polar solvent. Unlike the conventional method of decomposing the main chain and utilizing the difference in dissolution rate due to a decrease in molecular weight, a resist pattern with excellent resolution can be formed. Furthermore, since the reaction to generate polar groups is promoted by baking after exposure, sensitization is easily possible. Furthermore, since the resist material represented by the structural formula (I) has an aromatic ring in its unit structure, it exhibits high dry etching resistance.

Therefore, it becomes possible to form a resist pattern that exhibits high sensitivity and resolution and has excellent dry etching resistance, which is effective in further miniaturization and higher integration of semiconductor devices.

In the present invention, as a resist material, a copolymer represented by structural formula (I) and (e)-! as a proton generator are used. +epp- was used, but it goes without saying that other substances may be used. For example, as a proton generator (◎hsΦPF-
When using this, the sensitivity is 8μC/am" as in this example.
0.5 μm line and space (Line
& 5 pace) and etching resistance is 0F.
It was about the same level as PR-800. Also, structural formula (I)
When a polymer of structural formula (2) or a copolymer of structural formula (3) shown below is used instead of the copolymer of
C/cm" sensitivity and 0.5 μm 1ine &
Resolved at 5 pace. The dry etching resistance at this time was comparable to that of photoresist 0FPR-800.

further miniaturization of semiconductor devices,
Effective for high integration.

CHs　　　　　　C)Is

Claims (1)

[Claims] General formulas (I), (II), (III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲Mathematical formulas, chemical formulas, There are tables, etc.▼(III) (In the formula, X is -H, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
, -OR_2, -CO_2R_3(R_1, R_2, R
_3 is -H or alkyl group), halogen, alkyl group or nitrile group, Y is -CO-, -O-, alkylene group or phenylene group, Z is alkylene group or phenylene group, R is -H, -Si(CH_3 )_3 or an alkyl group. Further, Y and Z may be omitted. ) or a copolymer thereof and a compound that generates a protonic acid upon radiation irradiation, as a positive radiation-sensitive resist material.