JPH055991A - Negative type photoresist composition - Google Patents

Abstract

PURPOSE:To obtain excellent resolution, sensitivity, heat resistance, and film remaining rate by incorporating an alkali-soluble resin obtd. by condensation of an aldehyde and a specified compd., a melamine or benzoguanamine crosslinking agent, and an acid generating agent. CONSTITUTION:The resin compsn. contains an alkali-soluble resin obtd. by condensation of an aldehyde and a compd. expressed by formula, a crosslinking agent and an acid generating agent. In formula I, R1-R9 are independently alkyl groups or -OH groups in which two elements at the o-position and p-position are hydrogen atoms. The aldehyde used is, for example, formaldehyde. The addition condensation with the aldehyde is effected by a normal method at 60-120 deg.C for 2-30 hours. An org. acid or inorg. acid or divalent metal can be used as the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist composition which is a pattern forming material in semiconductor manufacturing.

[0002]

2. Description of the Related Art In recent years, miniaturization of integrated circuits has progressed with higher integration, and submicron pattern formation is now required. In particular, excimer laser lithography using an excimer laser as the light source is the next-generation 64MDR
Although it has made it possible to manufacture AM and the next-generation 256M DRAMs, at present, none of them has the performance required as a resist used therefor.

Japanese Patent Laid-Open No. 2-99957 discloses a method of forming a resist film on a substrate, forming a film containing a melamine compound, and then forming a pattern. However, it is troublesome because it needs to be applied twice. JP-A 1-293339 discloses a photoresist composition containing an oxystyrene resin as a resin component.
The result of resolving a 75 μm fine pattern is 64M.
It does not necessarily meet the required resolution for manufacturing DRAM and 254 MDRAM.

[0004]

The present invention is intended to provide a negative photoresist composition which is excellent in resolution, sensitivity, heat resistance and residual film rate.

[0005]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have obtained compounds obtained by condensing a compound represented by the following general formula (1) with aldehydes. It has been found that a negative photoresist composition containing an alkali-soluble resin, a crosslinking agent and an acid generator is excellent in resolution, sensitivity, heat resistance and residual film rate.

[0006]

[Chemical 4]

(In the formula, R _{1 to} R ₉ each independently represents an alkyl group, a hydrogen atom, a halogen atom, or an —OH group, and at least one of R _{1 to} R ₉ is an —OH group, and At least two of the o-position and the p-position with respect to the —OH group are hydrogen atoms.)

The negative photoresist composition of the present invention will be described in detail below. The resin used in the present invention is obtained by condensing the compound (1) with aldehydes in the presence of an acid catalyst.

The aldehydes used here include
For example, formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, glutaraldehyde, glyoxal, o- Methylbenzaldehyde, p-methylbenzaldehyde and the like are mentioned, and among these compounds, formaldehyde is particularly preferable because it is industrially easily available. These aldehydes can be used alone or in admixture of two or more.

The reaction of addition-condensing the compound (1) with aldehydes is carried out according to a conventional method. Reaction is usually 60
It is carried out at 120 ° C for 2 to 30 hours. As the catalyst, an organic acid or an inorganic acid, a divalent metal salt or the like is used. Specific examples include oxalic acid, hydrochloric acid, sulfuric acid, perchloric acid, p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, magnesium acetate and the like. The reaction may be carried out in bulk or a suitable solvent may be used.

Regarding the molecular weight of the resin used in the present invention, the polystyrene reduced weight average molecular weight (M _W ) determined by gel permutation chromatography (hereinafter referred to as GPC) is 2000 to 50,000, and more preferably
3000 to 30000 is suitable.

The compound (1) is prepared according to USP using m and p-isopropenylbenzene or a linear dimer thereof.
It can be synthesized by the method described in 3,288,864.

The alkyl group represented by R _{1 to} R ₉ in the compound (1) may have a linear or branched carbon number of 1 to 1.
No. 7, of which methyl group and ethyl group are more preferable. As the halogen atom, F atom, Cl atom, Br atom, I
Atoms are raised.

As the compound (1),

[0015]

[Chemical 5]

Etc. are exemplified. These may be used alone or as a mixture.

As the crosslinking agent used in the present invention, compounds represented by the following general formula (2) are preferable.

[0018]

[Chemical 6]

(In the formula, Z represents -NRR 'or a phenyl group. R, R', and R _{10 to} R ₁₃ each independently represent _a hydrogen atom, -CH ₂ OH or -CH ₂ OR _a. Represents an alkyl group.)

The melamine or benzoguanamine of the compound (2) can be easily obtained as a commercial product, and their methylol form can be obtained by condensation of melamine or benzoguanamine and formalin. Further, ethers can be obtained by modifying a methylol body with various alcohols by a known method.

The alkyl group represented by R _a of the compound (2) is preferably _a linear or branched alkyl group having 1 to 4 carbon atoms.

As the compound (2),

[0023]

[Chemical 7]

[0024]

[Chemical 8]

Examples thereof include, but are not limited to:

The acid generator used in the present invention is preferably a compound represented by the following general formula (3).

[0027]

[Chemical 9]

(In the formula, R ₁₄ and R ₁₅ each independently represent a hydrogen atom, an alkyl group, an alkenyl group or an alkoxyl group.)

Some compounds (3) are commercially available, but they can be synthesized by stirring and mixing sodium sulfinate and its derivative and acetophenone bromide.

The alkyl group represented by R ₁₄ and R ₁₅ of the compound (3) is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a methyl group or an ethyl group.
The alkenyl group preferably has 2 to 6 carbon atoms, and the alkoxyl group preferably has 1 to 4 carbon atoms.

As the compound (3),

[0032]

[Chemical 10]

Examples of such compounds include, but are not limited to:

The negative resist solution is prepared by mixing and dissolving an alkali-soluble resin, a crosslinking agent and an acid generator in a solvent. The composition ratio in the photoresist composition of the present invention is 20% by weight to 90% by weight of an alkali-soluble resin, 5% by weight to 50% by weight of a crosslinking agent, and 0.1% by weight to 20% by weight of an acid generator.
% By weight, preferably 40% by weight to 70% by weight, 10% by weight to 30% by weight, 1% by weight to 10% by weight, respectively
Is.

The solvent used is preferably one which has an appropriate drying rate and evaporates the solvent to give a uniform and smooth coating film. Examples of such a solvent include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, xylene, ethyl lactate, propylene glycol monoethyl ether acetate and the like. The amount of solvent is 3 when ethyl cellosolve acetate is used as the solvent.
It is 0 to 80% (% by weight). The resist composition obtained by the above method may further contain a small amount of resin, dye or the like as an additive, if necessary.

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, the number of parts indicates the number of parts by weight.

Synthesis Example 1 In a four-necked flask having an internal volume of 300 ml, 53.6 g of a compound represented by the following formula (p-OST cyclic dimer, manufactured by Mitsui Toatsu), 50.4 g of ethyl cellosolve acetate, 5%
6.08 g of oxalic acid was charged, the temperature was raised to 80 ° C., and 13.0 g of 37% formalin was added dropwise from a dropping funnel over 60 minutes while stirring. Then, it stirred at 110 degreeC for 10 hours. Then, it was neutralized, washed and dehydrated to obtain a solution of novolak resin in ethyl cellosolve acetate. This is designated as resin A. The polystyrene reduced weight average molecular weight of Resin A measured by GPC was 3,000.

[0038]

[Chemical 11]

Synthesis Example 2 Resin B (polystyrene-equivalent weight average molecular weight) was prepared in the same manner as in Synthesis Example 1 except that p-OST was changed to a compound obtained by subjecting m-isopropenylphenol to a reduction reaction in the presence of an acid catalyst. 3000) is obtained.

Example 1 9.33 parts of Resin A, 3 parts of hexamethylolmelamine hexamethyl ether as a crosslinking agent, and 1.5 parts of α-phenylsulfonylacetophenone as an acid generator were dissolved in 45 parts of ethyl cellosolve acetate. 0.2 of this formulated solution
A resist solution was prepared by filtering with a μm Teflon filter. This was applied to a silicon wafer washed by a conventional method to a thickness of 0.8 μm using a spin coater. The wafer was then prebaked in an oven at 100 ° C for 20 minutes. Then, the above coating film is passed through a chrome mask having a pattern and CM-2 with a Canon proximity mask aligner PLA-501F.
Deep UV exposure was performed using 50 mirrors. After the exposure, the wafer was heated on a hot plate at 100 ° C. for 3 minutes to carry out a crosslinking reaction in the exposed portion. A negative pattern was obtained by developing this with a 2.0% aqueous solution of tetramethylammonium hydride. By plotting the residual film thickness against the exposure dose, a sensitivity of 20 mj / cm ² (residual film ratio 50%
And the γ value of 9.50 (index of resolution) were obtained.

Example 2 A negative pattern was obtained in the same manner as in Example 1 except that tetramethylolbenzoguanamine tetramethyl ether was used as the crosslinking agent. A sensitivity of 30 mj / cm ² and a γ value of 8.50 was obtained.

Example 3 The cross-linking agent was tetramethylol benzoguanamine tetra-n
A negative pattern was obtained in the same manner as in Example 1 except that -butyl ether was used. A sensitivity of 32 mj / cm ² and a γ value of 8.30 was obtained.

Example 4 A negative pattern is obtained by carrying out the adjustment, coating, exposure and development of a resist solution in the same manner as in Example 1 except that resin B is used instead of resin A. The results are good.

Example 5 A negative pattern is obtained by carrying out adjustment, coating, exposure and development of a resist solution in the same manner as in Example 2 except that resin B is used instead of resin A. The results are good.

Example 6 Instead of α-phenylsulfonylacetophenone, p
A negative pattern was obtained in the same manner as in Example 1 except that toluenesulfonylacetophenone was used. A sensitivity of 22 mj / cm ² and a γ value of 8.95 was obtained.

Example 7 Instead of α-phenylsulfonylacetophenone, p
A negative pattern was obtained in the same manner as in Example 2 except that toluenesulfonylacetophenone was used. A sensitivity of 35 mj / cm ² and a γ value of 8.10 was obtained.

Comparative Example 1 Example 1 was repeated except that m, p-cresol copolymerized novolac (m / p ratio 4: 6, polystyrene-converted weight average molecular weight 4000), which had been conventionally used, was used in place of the resin A. A negative pattern was obtained in the same manner as in. With a sensitivity of 40 mj / cm ²
A γ value of 5.18 was obtained.

Comparative Example 2 Example 2 was repeated except that m, p-cresol copolymerized novolac (m / p ratio 4: 6, polystyrene-converted weight average molecular weight 4000) which was conventionally used was used in place of the resin A. A negative pattern was obtained in the same manner as in. With a sensitivity of 50 mj / cm ²
A γ value of 4.2 was obtained.

[0049]

The negative resist composition of the present invention is excellent in resolution, sensitivity, heat resistance and residual film rate. The composition of the present invention is also useful for KrF excimer laser.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromi Ueki 3-98, Kasugadeka, Konohana-ku, Osaka-shi, Osaka Sumitomo Chemical Co., Ltd.

Claims (1)

Claims: 1. An alkali-soluble resin obtained by condensing a compound represented by the following general formula (1) with an aldehyde:
A negative photoresist composition containing a crosslinking agent and an acid generator. [Chemical 1] (In the formula, R _{1 to} R ₉ each independently represent an alkyl group, a hydrogen atom, a halogen atom, or an —OH group, and R _{1 to} R 9
_At least one of ₉ is an -OH group, and at least two of the o-position and the p-position with respect to the -OH group are hydrogen atoms. 2. The negative photoresist composition according to claim 1, wherein the crosslinking agent is a compound represented by the following general formula (2). [Chemical 2] (In the formula, Z represents -NRR 'or a phenyl group. R,
R ′ and R _{10 to} R ₁₃ are each independently a hydrogen atom, —CH ₂
OH, represents a -CH ₂ OR _a. R _a represents an alkyl group. 3. The negative photoresist composition according to claim 1, wherein the acid generator is a compound represented by the following general formula (3). [Chemical 3] (In the formula, R ₁₄ and R ₁₅ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an alkoxyl group.)