JP2959160B2 - Negative photoresist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist composition used as a pattern forming material in semiconductor production.

[0002]

2. Description of the Related Art In recent years, integrated circuits have been miniaturized in accordance with high integration, and submicron pattern formation has now been required. In particular, excimer laser lithography using excimer laser as the light source is the next generation of 64M DRAM.
In addition, although it is possible to manufacture the next-generation 256M DRAM, at present, there is no material which sufficiently satisfies the performance required as a resist used for this.

JP-A-2-99957 discloses that after forming a resist film on a substrate, a film having a melamine compound is formed,
Thereafter, a method of forming a pattern is disclosed. However, it is troublesome because it requires two coatings. JP Hei 1
JP-293339 discloses a photoresist composition containing a hydroxystyrene-based resin as a resin component, but the result of resolving a 0.75-μm fine pattern according to the examples is that 64M DRAM and 256M The resolution required for manufacturing DRAM is not always satisfied.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a negative photoresist composition having excellent resolution, sensitivity, heat resistance and residual film ratio.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve these problems, and as a result, the following general formula (1)

[0006]

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(Wherein, R _{1 to} R ₉ each independently represent 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; At least two of the o- and p-positions with respect to the -OH group are hydrogen atoms.) And an alkali-soluble resin obtained by condensing the compound with an aldehyde, a crosslinking agent and an acid generator. It has been found that the resulting negative photoresist composition is excellent in resolution, sensitivity, heat resistance and residual film ratio.

Hereinafter, the negative photoresist composition of the present invention will be described in detail.

The compound represented by the above general formula (1)
-Or p-isopropenylphenol or a linear dimer thereof can be synthesized by the method described in U.S. Patent No. 3,288,864. As the alkyl group represented by R _{1 to} R ₉ in the general formula (1),
Those having 1 to 7 carbon atoms which may be linear or branched,
Further, a methyl group or an ethyl group is preferable. Examples of the halogen atom include an F atom, a Cl atom, a Br atom, and an I atom.

Specific examples of the compound of the general formula (1) include the following, and these can be used alone or in combination for the condensation reaction with aldehydes.

[0011]

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The resin used in the present invention has the general formula (1)
Can be obtained by condensing the compound represented by with an aldehyde 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. Particularly, formaldehyde is preferred in that it is industrially easily available. These aldehydes can be used alone or in combination of two or more.

The reaction of addition-condensing the compound of the formula (1) with aldehydes can be carried out according to a conventional method.
The reaction is usually performed at 60 to 120 ° C for 2 to 30 hours.
As the catalyst, an organic acid, an inorganic acid, a divalent metal salt or the like is used. Specific examples of the catalyst 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. In addition, the reaction may be performed in bulk or using a suitable solvent.

[0014] thus obtained, the molecular weight of the alkali-soluble resin used in the present invention are polystyrene-reduced weight average molecular weight determined by gel permeation chromatography (hereinafter referred to as GPC) (M _W) is
Suitably, it is in the range of 2,000 to 50,000, more preferably in the range of 3,000 to 30,000.

As the crosslinking agent used in the present invention, a compound represented by the following general formula (2) is preferable.

[0016]

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(Wherein Z represents -NRR 'or a phenyl group, and R, R' and R ₁₀ -R ₁₃ each independently represent
It represents a hydrogen atom, -CH ₂ OH or -CH ₂ OR _a, wherein in R _a represents an alkyl group. )

In the general formula (2), the alkyl group represented by R _a has 1 to 4 carbon atoms which may be linear or branched.
An alkyl group of 4 is preferred.

Melamine or benzoguanamine corresponding to the general formula (2) can be easily obtained as a commercial product, and their N-methylols can be obtained by condensation of melamine or benzoguanamine with formaldehyde. Further, N-methylol ethers can be obtained by modifying an N-methylol compound with various alcohols by a known method. Specific examples of the compound of the general formula (2) include the following, but are not limited thereto.

[0020]

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[0021]

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As the acid generator used in the present invention, a compound represented by the following general formula (3) is preferable.

[0023]

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

The alkyl group represented by R ₁₄ and R ₁₅ in the formula (3) is preferably an alkyl group having 1 to 5 carbon atoms which may be linear or branched, and more preferably a methyl group or an ethyl group. . Examples of the alkenyl group include those having 2 to 6 carbon atoms, and examples of the alkoxyl group include those having 1 to 4 carbon atoms.

Some of the compounds of the general formula (3) are commercially available, but this compound can be synthesized by stirring and mixing sodium sulfinate and acetophenone bromide or its nucleus-substituted product. .

Specific examples of the compound represented by formula (3) include, but are not limited to, the following.

[0028]

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The composition ratio in the photoresist composition of the present invention is usually 20 to 90% by weight of an alkali-soluble resin, 5 to 50% by weight of a crosslinking agent, and 0 to 50% by weight of an acid generator, based on the total solid content. 0.1-20% by weight, preferably 40-70% by weight, 10-30% by weight, and 1-10% by weight, respectively.

The preparation of the negative resist solution is carried out by mixing and dissolving an alkali-soluble resin, a cross-linking agent, an acid generator and, if necessary, other components in a solvent. The solvent to be used preferably has an appropriate drying rate and gives a uniform and smooth coating film by evaporation of the solvent. 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, and propylene glycol monoethyl ether acetate. When ethyl cellosolve acetate is used, the amount of the solvent is usually 30 to 80% by weight based on the total amount of the composition containing the solvent.

The resist composition obtained by the above method is
Further, if necessary, a small amount of a resin or a dye may be added as an additive.

[0032]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The percentages and parts in the examples are on a weight basis.

Synthesis Example 1 A compound represented by the following formula (p-OST cyclic dimer, manufactured by Mitsui Toatsu) was placed in a four-necked flask having an inner volume of 300 ml.
53.6 g, 50.4 g of ethyl cellosolve acetate and 6.08 g of 5% oxalic acid were charged, and the temperature was raised to 80 ° C .. While stirring, 13.0 g of 37% formalin was added dropwise from the dropping funnel over 60 minutes. Thereafter, the mixture was stirred at 110 ° C. for 10 hours. Next, neutralization, washing and dehydration were performed to obtain a solution of novolak resin in ethyl cellosolve acetate. This is designated as resin A. The weight average molecular weight in terms of polystyrene of the resin A measured by GPC was 3,000.

[0034]

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Synthesis Example 2 Resin B was prepared in the same manner as in Synthesis Example 1 except that a compound obtained by cyclizing m-isopropenylphenol in the presence of an acid catalyst was used instead of p-OST. (Weight average molecular weight in terms of polystyrene of about 3,000) is obtained.

Example 1 9.33 parts of resin A (solid content), 3 parts of hexamethylolmelamine hexamethyl ether as a crosslinking agent, and 1.5 parts of α-phenylsulfonylacetophenone as an acid generator
Parts were dissolved in 45 parts of ethyl cellosolve acetate.
The prepared solution was filtered through a 0.2 μm Teflon filter to prepare a resist solution. This was applied to a silicon wafer cleaned by a conventional method to a thickness of 0.8 μm using a spin coater. Next, the wafer was pre-baked in an oven at 100 ° C. for 20 minutes. Through this coating film, through a chrome mask with a pattern, Canon Proximity Mask Aligner PLA
Deep UV exposure was performed with a -501F using a CM-250 mirror.

After exposure, the wafer is placed on a hot plate for 10 minutes.
Heating was performed at 0 ° C. for 3 minutes to perform a crosslinking reaction in the exposed portion. This was developed with a 2.0% aqueous solution of tetramethylammonium hydroxide to obtain a negative pattern. By plotting the remaining film thickness against the exposure amount, 20 mJ /
Sensitivity of cm ² (irradiation at 50% residual film ratio) and γ value of 9.50
(Indicator of resolution) was obtained.

Example 2 A negative pattern was obtained in the same manner as in Example 1 except that the crosslinking agent was changed to tetramethylolbenzoguanamine tetramethyl ether. As a result, a sensitivity of 30 mJ / cm ² and a γ value of 8.50 were obtained.

Example 3 The crosslinking agent was tetramethylolbenzoguanaminetetra-n
A negative pattern was obtained in the same manner as in Example 1 except that -butyl ether was used. As a result, a sensitivity of 32 mJ / cm ² and a γ value of 8.30 were obtained.

Example 4 A negative pattern is obtained by preparing, applying, exposing and developing a resist solution in the same manner as in Example 1 except that resin B is used instead of resin A. The result is good.

Example 5 A negative pattern is obtained by preparing, applying, exposing and developing a resist solution in the same manner as in Example 2 except that resin B is used instead of resin A. The result is good.

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

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

Comparative Example 1 In place of resin A, m- / p-
A negative pattern was obtained in the same manner as in Example 1, except that cresol copolymerized novolak (m / p ratio 4: 6, polystyrene equivalent weight average molecular weight 4,000) was used. as a result,
A sensitivity of 40 mJ / cm ² and a γ value of 5.18 were obtained.

Comparative Example 2 Instead of resin A, m- / p-
A negative pattern was obtained in the same manner as in Example 2 except that cresol copolymerized novolak (m / p ratio 4: 6, polystyrene equivalent weight average molecular weight 4,000) was used. as a result,
A sensitivity of 50 mJ / cm ² and a γ value of 4.2 were obtained.

[0046]

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

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiromi Ueki 3-1-1, Kasuganaka, Konohana-ku, Osaka-shi, Osaka Sumitomo Chemical Co., Ltd. (56) References JP-A-59-113435 (JP, A) JP-A-60-39642 (JP, A) JP-A-63-97948 (JP, A) JP-A-64-55553 (JP, A) JP-A-64-54441 (JP, A) 289947 (JP, A) JP-A-4-226458 (JP, A) JP-A-60-70444 (JP, A) JP-A-4-199152 (JP, A) JP-A-3-223866 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G03F 7/038 G03F 7/004

Claims (3)

(57) [Claims] (1 ) The following general formula (1 ) : (Wherein, each R ₁ to R ₉ independently represents an alkyl group, a hydrogen atom, a halogen atom or -OH group, R ₁ to R
_At least one of ₉ is -OH group, and at least two of o-position and p-position with respect to the -OH group are hydrogen atoms. ) And aldehydes
Alkali-soluble resin, crosslinking agent and acid generator
A negative photoresist composition containing a raw material. 2. The crosslinking agent according to the following general formula (2 ) : ## STR2 ## (Wherein, Z is to display the -NRR 'or a phenyl group, R,
R 'and R ₁₀ to R ₁₃ are each independently a hydrogen atom, -
It represents a CH ₂ OH or -CH ₂ OR _a, wherein in R _a represents an alkyl group. 2. The compound according to claim 1, which is a compound represented by the formula:
The negative photoresist composition described above. 3. An acid generator according to the following general formula (3 ) : ## STR3 ## (Wherein R ₁₄ and R ₁₅ are each independently a hydrogen atom,
Represents an alkyl group, an alkenyl group or an alkoxyl group. 3. The compound according to claim 1, which is a compound represented by the formula:
Negative photoresist compositions.