JPH02239251A - resist composition - Google Patents

Abstract

PURPOSE:To improve resolution by mixing a diazido compd. with a homopolymer of a specified silicon-contg. alpha-substd. acrylic ester or a copolymer of the ester with specified 2,2,2-trifluoroethyl acrylate. CONSTITUTION:A diazido compd. is mixed with a homopolymer of a silicon- contg. alpha-substd. acrylic ester represented by formula I or a copolymer of the ester with 2,2,2-trifluoroethyl (alpha-trifluoromethyl) acrylate represented by formula II. In order to produce a remarkable effect, the diazido compd. is added by 1-15wt.% of the amt. of the polymer when the mol. wt. of the polymer is <=600,000 and by 1-5wt.% when the mol. wt. is >600,000. The resolution of the resulting resist compsn. can be improved and the compsn. can be practically used to form the upper layer of a resist having a two-layered structure.

Description

[Detailed Description of the Invention] [Summary] With regard to the resist composition used as the upper layer of the two-layer resist method, the following general Formula (1)
A homopolymer of a silicon-containing α-substituted acrinole-based ester represented by, or a 2,2.2- silicon-containing α-substituted acrylic ester represented by the following general formula (2).
}A resist composition is prepared by mixing a diazide compound with a copolymer of trifluoroethyl (α-trifluoromethyl)acrylate.

χCI! =C ・・・・・・(1
)cozR Koite x is CFs. Cl lCH3, CN, CHzCO
zYY is CFI llga*+ (ns=1 ~ 4)+
-0+-CHz-O, -Si(CHa)xL. -CHg
Si(CHs)R+ Rl -cow or -CH2Si(CHa) sR is -Si(CH,)J+. -CHzSi(CL)R+[
Field of Industrial Application] The present invention relates to a resist composition with excellent oxygen plasma etching resistance and resolution. Thin film formation technology and photolithography (photolithography or electron beam lithography) are often used to form semiconductor integrated circuits, and as these technologies advance, semiconductor unit elements are becoming increasingly finer and integrated into LSIs and VLSIs. The circuit has been put into practical use.

In other words, regarding the wiring pattern, a resist is coated on a thin film made of a wiring forming material formed on the substrate to be processed, and this is selectively exposed to ultraviolet light and then developed to form a resist pattern. A method of forming a fine wiring pattern by performing wet etching or dry etching, or a method of narrowing down the diameter of an electron beam to a minute size and scanning the resist, and developing it to create a resist pattern.
A method of forming fine wiring patterns by etching is used.

In this way, fine patterns are formed using thin film formation technology and photoetching technology, and the minimum pattern width is 1 μm.
As miniaturization has progressed to below \, electron beams have come to be used as exposure light sources instead of ultraviolet rays.

In other words, the formation of fine patterns by ultraviolet light exposure is limited to about 1 μm due to wavelength limitations, whereas the wavelength of electron beams varies depending on the accelerating voltage and is much shorter, about 0.1 μm. Pattern formation becomes possible.

Therefore, there is a need for practical use of electron beam resists that have good dry etching resistance, sensitivity, and resolution.

[Conventional technology]

In the manufacturing process of semiconductor devices such as LSI and VLSI, multilayering of circuits is required, and in this case, if there is a wiring pattern in the lower layer, a step of 1 to 2 μm may be created on the surface of the insulating layer formed on top of the wiring pattern. This often occurs, and in such cases, if the conventional single-layer resist method is applied, it becomes impossible to form fine patterns with high precision.

- Therefore, a two-layer resist is used, in which a lower resist layer is first used to flatten it, and a thin upper resist layer with excellent oxygen dry etching resistance is formed on top of this and dry etched to form a fine pattern. In the two-layer resist, a material that can be easily dry-etched by oxygen (0.0%) plasma, such as phenol novolac resin or cresol novolac resin, is coated as a lower layer resist to a thickness of, for example, about 2 μm and flattened, and then the upper layer resist is applied on top of this. In the case of a positive type, the bonds between atoms are broken by electron beam irradiation, making it soluble in the developer, but in the non-irradiated area, a polymer material resistant to 02 plasma is used. It is formed by applying a thin layer of about .2 to 0.3 μm.

Therefore, as a positive-type electron beam resist with excellent OJIE resistance, a homopolymer of methacrylic acid (trimethylsilylmethyl) ester shown in the following general formula (3) or this methacrylic acid (trimethylsilylmethyl) ester and general formula (2) was used. 2.2.2- }Refluoroethyl (
Copolymers with α-trifluoromethyl) acrylate have been proposed.

\C (hcHzsicHz ?) These materials have excellent plasma resistance and are soluble in many organic solvents such as isobrobyl alcohol and toluene, so there is a sufficient difference in solubility between exposed and unexposed areas. There is no developing solution available, and therefore stable resolution that can support submicron patterns has not been obtained.

Therefore, there has been a demand for the development of a positive resist with excellent resolution and high sensitivity.

[Problem to be solved by the invention]

As mentioned above, it has been proposed to use a homopolymer of methacrylic acid (trimethylsilylmethyl) ester containing silicon (St) atoms or a copolymer of this and acrylic ester as a positive-type upper layer resist with a two-layer structure. There is.

However, although these resists have excellent resistance to Ot plasma, they are soluble in many organic solvents, making it impossible to obtain sufficient resolution. Therefore, it is a challenge to develop a positive resist with excellent resolution.

[Means to solve the problem]

The above problem can be solved by using a homopolymer of silicon-containing α-substituted acrylic ester represented by the following general formula (1), or by combining this silicon-containing α-substituted acrylic ester with the following general formula (
2) 2.2.2-trifluoroethyl (α
(1) The problem can be solved by using a resist composition formed by mixing a diazide compound with a copolymer with trifluoromethylacrylate.

Y Ko\ and X is CF3. Cl, CH! I, C.N. Hz
COzYY is C, L, 1++ (n = 1 ~ 4), -
<E), -Cllz-Q, -St (CH3) zR
+. -CHzSi(CHs)R+ R. -CH3 or -CHzSr CCHJ xR is -Si (CHz) zR1, -CHzSi (CHz
)R+ [Function] The present invention involves adding and mixing a diazide compound as a method for improving the resolution of a resist made of a St-containing methacrylic ester monopolymer or a copolymer of this and an acrylic ester.

In other words, the reason why these resists have poor resolution is that not only the exposed areas but also the unexposed areas are soluble in most organic solvents, including isopropyl alcohol and toluene. Therefore, the inventors thought of reducing the solubility by crosslinking these monobolymer or copolymers, and chose a diazide compound as the crosslinking agent. It is known that when mixed with the above-mentioned monobolymer or copolymer and heated, the diazide compounds interpenetrate with each other and crosslinking progresses.

Therefore, the present invention uses a monopolymer of St-containing methacrylic acid ester containing a diazide compound or a copolymer of this and an acrylic acid ester as a resist, and includes a heat treatment process in which the resist is coated on a substrate to be processed and dried. It is used to generate crosslinking and change the solubility in spinal solvents.

In most cases of photolithography, resist is applied onto the substrate by the Subin coating method, and after the coating film formation process, drying is performed to remove the solvent. However, crosslinking progresses during this heat treatment step. As a result of the experiment, the heat treatment temperature for promoting thermal crosslinking was 1
A temperature of 30°C or higher is appropriate.

Incidentally, as the diazide compound, those shown in the following one shell two are typical.

4.4 -Diazidochalcone N, -Q-CHtomiCM-CO-Q-Nff ・・
...(4) 4,4-Diazidodiphenylmethane N: I-(E)-CH*- (E)-Ns
--(5) 4.4'-Diazidostilbenzene N s - ()- C }l = C H - <E
> − N s ・・・・・・(6) 4,4′
-Diazidobenzalacetone N3-(E)-Cl=Cll-CO-CI=C}I-
<E)-N3...(7) Now, as mentioned above, adding a diazide compound and thermally crosslinking improves the chemical resistance of the unexposed area, increasing the range of developer choices. As a result, resolution can be improved.

The addition amount of the diazide compound, which has a remarkable effect, is determined when the molecular weight of the volima is eoo. If the molecular weight is less than ooo, it is 1 to 15% of the weight of the volima, but if the molecular weight is more than this, it is 1 to 5%.
% is appropriate.

〔Example〕

Example 1: (Example of use of homopolymer) General formula (3) as St-containing α-substituted acrylic ester
Using methacrylic acid (trimethylsilylmethyl) ester shown in
0) was synthesized.

Next, 30 g of this homopolymer was dissolved in 1j2 of ethylbenzene, and 4.4-diazide chalcone [general formula (4)] was added thereto in an amount of 5% of the weight of the volima and mixed well to prepare a resist solution.

This was spin-coated onto a Si wafer to a thickness of about 3,000 mm, and dried by heating at a temperature of 200° C. for 1 hour in a nitrogen (N2) atmosphere.

Next, after exposure to an electron beam with an accelerating voltage of 20 K eV,
As a result of developing for 5 minutes using methanol as a developer, 9.6
A sensitivity of 0.3 μm can be obtained.
was able to resolve the lines and spaces of

Comparative Example 1: (When diazide is not added) A resist was applied and exposed in the same manner as in Example 1, except that a resist solution having the composition of Example 1 and containing no diazide compound was used.

When methanol was used as a developing solution, all of this was dissolved and could not be developed.

Next, water was added to isobrobyl alcohol in a ratio of 10:1 to make a developer, and development was performed using this for 10 minutes. As a result, the sensitivity was poor at 64 μC/cm, and the line and Comparative Example 2: (When the amount of diazide added is not appropriate) In Example 1, when the amount of 4,4'-diazide chalcone added was as small as 0.05%, No change in solubility in the developer was observed, and it was the same as when no developer was added.

Furthermore, when the amount added was as large as 20%, the exposed areas were difficult to dissolve and a positive resist pattern could not be obtained.

Example t; (When using another diazide compound) In place of 4.4-diazide chalcone in Example 1, 4.4'-diazide phenylmethane [general formula (5)]
, 4.4-Diazidostilbenzene [general formula (
6)), 4.4-Diazidobenzalacetone [
General formula (6)] by adding 5% of the weight of Borima to each
A different type of resist solution was prepared, and coated on a Si wafer to a thickness of approximately 3000 nm in the same manner as described in Example 1, and heated at a temperature of 200'C for 1 hour in a nitrogen (N2) atmosphere. Dry.

Next, after exposure to an electron beam with an accelerating voltage of 20 KaV, development was performed for 5 minutes using methanol as a developer. As a result, a sensitivity of 9.6 μC/cm2 could be obtained as in Example 1, and 0.
．． It was able to resolve lines and spaces of 3 μm.

Example 3 (When the molecular weight of the homopolymer is different) Example 1
The molecular weight of methacrylic acid (trimethylsilylmethyl) ester represented by general formula (3) is approximately 800.00.
The experiment was carried out in the same manner as in Example 1 except that 2% of 4-4'-diazide chalcone shown in general formula (4) was added to the polymer of No.
It was possible to obtain a sensitivity of cII12 and resolve lines and spaces of 0.3 μm.

Comparative Example 3: In Example 3, when 5% of 4-4'-diazide chalcone represented by general formula (4) was added, the exposed area no longer melted.

In addition, when 4-4-diazide chalcone was not added to the borimer with a molecular weight of 800.000, the sensitivity was 1 after developing for 5 minutes with a developer containing isopropyl alcohol and water = 5:1.
4μC/cff1! It resolved lines and spaces of 0.5 μm.

Example 4: (Copolymer use example) Methacrylic acid (trimethylsilylmethyl) ester represented by general formula (3) and 2,2,2-trifluoroethyl (α-trifluoromethyl) acrylate represented by general formula (2) copolymer with (copolymerization ratio 7:3, molecular weight 300,
000) was conducted in the same manner as in Example 1, and as a result of development using toluene, a sensitivity of 8.0 μC/CIm2 could be obtained, and a line and space of 0.5 μm could be resolved. did it.

Comparative Example 4: In Example 4, when the diazide compound was not mixed and when cyclohexane was used as the developer, all the compounds were dissolved and development could not be performed.

In addition, when using a mixture of n-octyl alcohol and methanol = 5:1 as the developer, the anger level is 50 after 4 minutes of development.
μC/cm” and 3.0 μm lines and spaces could not be resolved.

Example 5: Using the Si-containing α-substituted acrylic ester represented by the following general formula (8), the same experiment as in Example 1 was conducted on this homopolymer with a molecular weight of 500,000.

However, cyclohexane is used as the resist solvent and isopropyl alcohol is used as the developer.
Developed for minutes.

As a result, it was possible to obtain a sensitivity of 9.6 μC/cm" and resolve lines and spaces of 0.5 μC. Comparative Example 5: No diazide compound was added in Example 5. In this case, a water:isopropyl alcohol=1:io developer was used for 20 minutes, and as a result, the sensitivity was poor at 64 μC/cm”, and even 3.0 μl of line and space could not be resolved. ．． [Effects of the Invention] By carrying out the present invention, the resolution, which has been poor until now, can be improved, and it becomes possible to put it to practical use as an upper layer resist of a two-layer structure.

Claims (1)

[Scope of Claims] A homopolymer of a silicon-containing α-substituted acrylic ester represented by the following general formula (1), or a homopolymer of the silicon-containing α-substituted acrylic ester and 2 represented by the following general formula (2).
, 2,2-trifluoroethyl (α-trifluoromethyl) acrylate, and a diazide compound mixed therein. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(1) Here, X is CF_3, Cl, CH_3, CN, CH_2
CO_2Y Y is C_nH_2_n_+_1 (n=1~4), ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -Si(CH_3
)_2R_1, -CH_2Si(CH_3)R_1 R_1-CH_3 or -CH_2Si(CH_3)_
3 R is -Si(CH_3)_2R_1, -CH_2Si(
CH_3) R_1 ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(2)