JPH0588366A - Negative photoresist composition - Google Patents

Abstract

PURPOSE:To obtain a negative photoresist composition having high sensitivity, resolution and dry etching resistance by incorporating specified alkali-soluble resin, cross-linking agent and photo-acid generating agent. CONSTITUTION:An alkali-soluble resin obtained by condensing a compd. shown by formula I and aldehyde, a cross-linking agent and the optical acid generating agent shown by formula II. In formula I, R<1>, ...R<9> are hydrogen atom, alkyl, alkenyl, halogen atom, -OH, etc., and at least one among the R<1>, ...R<9> is -OH. In formula II, R<10>, ...R<12> are alkyl, aryl, alkenyl, aralkyl, piperidino group, etc. Consequently, a negative photoresist composition excellent in sensitivity and resolution is obtained while maintaining the resist characteristics such as heat resistance, redidual film ratio, coating property, profile, etc.

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 the production of semiconductors, and more particularly, it has high sensitivity, high resolution and high dry etch resistance suitable for deep ultraviolet and excimer laser lithography. The present invention relates to a negative photoresist composition having

[0002]

2. Description of the Related Art In recent years, integrated circuits have become finer with higher integration, and now submicron pattern formation is required. In particular, excimer laser-lithography-makes it possible to manufacture next-generation 64 MDRAM and 256 MDRAM. With such changes in the light source, the resist is required to have the following new performances in addition to the conventional performances such as heat resistance, residual film rate, and profile. A) High sensitivity to the above light source. B) High resolution.

JP-A-1-293339 discloses a composition in which a polymer containing hydroxystyrene and a photoacid generator containing a sulfonic acid ester group are combined with a crosslinking agent. However, it leaves a problem in terms of sensitivity and resolution and does not satisfy the required performance.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a negative photoresist composition having excellent sensitivity and resolution while maintaining various resist properties such as heat resistance, residual film ratio, coating property and profile. Is.

[0005]

Means for Solving the Problems As a result of intensive studies for solving these problems, the present inventors have obtained a compound represented by the following general formula (1) by condensation with an aldehyde. Alkali-soluble resin,

[0006]

[Chemical 4]

(In the formula, R ^{1 to} R ⁹ are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted acyl group, a halogen atom, or Represents an —OH group, R ^{1 to} R
^At least one of ⁹ is an -OH group and has at least two hydrogen atoms in the o-position or the p-position with respect to the -OH group. ) Crosslinking agent and photoacid generator represented by the following general formula (2)

[0008]

[Chemical 5]

(In the formula, R ¹⁰ , R ¹¹ and R ¹² are each independently an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted alkenyl group or a substituted An aralkyl group, an optionally substituted piperidino group, It represents a hydrogen atom, an optionally substituted alkyl group or an optionally substituted aryl group. However, R ¹⁰ and R ¹¹
At least one of R ¹² and R ¹² represents a mono-, di- or trihalogen-substituted methyl group. It has been found that the negative photoresist composition containing) is excellent in sensitivity and resolution.

The negative photoresist composition of the present invention will be described in detail below. The alkali-soluble novolak resin used in the present invention is obtained by condensing the compound represented by the general formula (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 represented by the general formula (1) with aldehydes is 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 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.

The compound represented by the general formula (1) is m-, p
-Isopropenylphenol or a linear dimer thereof can be used for synthesis according to the method described in US Pat. No. 3,288,864.

The optionally substituted alkyl group represented by R ^{1 to} R ⁹ in the general formula (1) may be linear or branched, and those having 1 to 7 carbon atoms may be a methyl group or an ethyl group. , N-propyl group, i-propyl group and the like are preferable.
Examples of the substituent of the optionally substituted alkyl group include a halogen atom and an acyl group. The optionally substituted alkenyl group may be linear or branched, and preferably has 2 to 4 carbon atoms. The acyl group which may be substituted may be linear or branched and is preferably one having 2 to 7 carbon atoms, and further preferably an acetyl group, a propionyl group, a butyryl group, an i-butyryl group and the like. Examples of the substituent of the optionally substituted alkenyl group and acyl group include a halogen atom and an aryl group. Examples of the halogen atom include F atom, Cl atom, and Br atom.

Particularly preferred compounds represented by the general formula (1) are:

[0016]

[Chemical 6]

And the like. These may be used alone or as a mixture.

The novolak resin of the present invention may be used alone, or may be used as a mixture with another alkali-soluble resin.

As the alkali-soluble resin that can be mixed,
Phenol novolac resin, cresol novolac resin, xylenol novolac resin, vinylphenol resin, isopropenylphenol resin, vinylphenol and styrene, acrylonitrile, copolymer of methylmethacrylate or methacrylate, isopropenylphenol and styrene, acrylonitrile, methylmethacrylate or methacrylate And a resin obtained by introducing an alkyl group containing silicon into these resins and copolymers. You may use these individually or in multiple numbers.

Regarding the molecular weight of the resin used in the present invention, the polystyrene-equivalent weight average molecular weight (Mw) determined by gel permeation chromatography (GPC method) is 1000 to 1000.
0, preferably 1500-8000, more preferably 2000-5000
Is appropriate.

The compound represented by the general formula (2) used as a photo-acid generator in the present invention is described in, for example, Wakabayashi et al., Bull. Chem. Soc. Japan, 42 , 2924 (1969), US Patent. 3,987,037 or FC Schaefer et.al.
The corresponding nitrile compounds can be reacted with aluminum bromide in the presence of hydrogen chloride according to J. Org. Chem., 29 1527 (1964) or can be synthesized using the corresponding imidate.

In the general formula (2), two or more of R ¹⁰ , R ¹¹ and R ¹² are trichloromethyl groups or
It is preferably a tribromomethyl group. The optionally substituted alkyl group represented by R ¹⁰ , R ¹¹ and R ¹² in the general formula (2) may be linear or branched, and has 1 to 7 carbon atoms, and further a methyl group or an ethyl group. Group, n-propyl group, i-propyl group, n-butyl group,
A t-butyl group and the like are preferable. Examples of the substituent of the alkyl group which may be substituted include halogen atoms such as Cl atom and Br atom. The optionally substituted aryl group of R ¹⁰ , R ¹¹ and R ¹² has 1 to 2 rings,
Further, a phenyl group and a naphthyl group are preferable. The substituent of the optionally substituted aryl group is a methyl group,
Alkyl group having 1 to 7 carbon atoms such as ethyl group, propyl group and butyl group, alkoxy group having 1 to 7 carbon atoms such as methoxy group, ethoxy group and propoxy group, halogen atom such as Cl atom and Br atom, nitro group , A cyano group and a dialkylamino group having 1 to 7 carbon atoms such as a dimethylamino group and a diethylamino group. The optionally substituted alkenyl group for R ¹⁰ , R ¹¹ and R ¹² may be linear or branched, and is preferably one having 2 to 7 carbon atoms. Examples of the substituent of the optionally substituted alkenyl group include an aromatic nucleus such as a phenyl group and a naphthyl group, and a heterocyclic group such as benzoxazole and benzothiazole. Further, these nuclei may be substituted with a halogen atom such as Cl atom or Br atom, an alkoxy group having 1 to 7 carbon atoms, an acetyl group or a nitro group. The optionally substituted alkyl group of R ^{13 to} R ¹⁶ may be linear or branched. R ^{13 to} R ¹⁶ are preferably an alkyl group having 1 to 6 carbon atoms, and further, a methyl group, an ethyl group, an n-propyl group, n
A butyl group and the like, and a phenyl group.

As the compound represented by the general formula (2),
Compounds described in the above literature, for example, 2-phenyl-4,6
-Bis (trichloromethyl) -s-triazine, 2-
(P-Acetylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl ) -4,6-Bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2 ', 4'-dichloro) Phenyl) -4,6
-Bis (trichloromethyl) -s-triazine, 2,
4,6-Tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl)-
s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-n-nonyl-4,6-bis (trichloromethyl) -s-triazine , 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2,4,6
-Tris (dibromomethyl) -s-triazine, 2-amino-4-methyl-6-tribromomethyl-s-triazine, and 2-methoxy-4-methyl-6-trichloromethyl-s-triazine.

In addition, compounds described in British Patent 1,388,492, such as 2-styryl-4,6-bis (trichloromethyl) -s-triazine and 2- (p-methylstyryl) -4,6-bis ( Trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-
Methoxystyryl) -4-amino-6-trichloromethyl-s-triazine, compounds described in JP-A-53-133,428, for example, 2- (4-methoxy-naphth-1-yl) -4,6-bis. -Trichloromethyl-s-triazine, 2- (4-ethoxy-naphth-1-yl) -4,6
-Bis-trichloromethyl-s-triazine, 2- [4
-(2-Ethoxyethyl) naphth-1-yl] -4,6
-Bis (trichloromethyl) -s-triazine, 2-
(4,7-Dimethoxy-naphth-1-yl) -4,6-
Examples thereof include bis (trichloromethyl) -s-triazine and 2- (acenaphtho-5-yl) -4,6-bis (trichloromethyl) -s-triazine.

Japanese Patent Application No. 61-186238 and Japanese Patent Application Laid-Open No. 63-15354.
No. 2 compound, for example,

[0026]

[Chemical 7]

However, the present invention is not limited to these.

Of these, particularly preferable are:
4,6-Tris (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl)
-S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2- (p-acetylphenyl) -4 , 6-bis (trichloromethyl)
-S-triazine, 2- (p-chlorophenyl) -4,
6-bis (trichloromethyl) -s-triazine, 2-
Examples include (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine. These compounds may be used alone or in combination of two or more.

Examples of the cross-linking agent used in the present invention are as follows.

[0030]

[Chemical 8]

[0031] ²³ , R ¹⁷ , R ¹⁸ , R ²⁰ and R ²¹ each independently represent a hydrogen atom, —CH ₂ OH or —CH ₂ OR ²⁴ . R ²⁴ represents an alkyl group. )

[0032]

[Chemical 9]

In the compound represented by the above general formula (3), the methylol compound is obtained by condensing a melamine or benzoguanamine derivative with formaldehyde in a basic manner. The compounds represented by the formulas (4) and (5) are p
Obtained by condensing cresol or 4-tert-butylphenol with formaldehyde in a basic manner. The compounds represented by the formulas (6) to (9) are disclosed in JP-A-1-
It is a compound described in 293339.

Among them, the compound represented by the above general formula (3) is preferable. Examples of the optionally substituted aryl group of R ¹⁹ in the general formula (3) include phenyl, 1-naphthyl, 2-naphthyl, and the like, and the substituents are an alkyl group, an alkoxy group, a nitro group, a halogen atom, etc. Can be given. The alkyl group represented by R ²⁴ is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group.

Specific examples of the general formula (3) include the following compounds.

[0036]

[Chemical 10]

The cross-linking agent used in the present invention is not limited to the above-exemplified compounds, and analogs and derivatives can also be used. These compounds may be used alone or in combination of two or more.

The composition ratio in the photoresist composition of the present invention is 40% by weight to 90% by weight of alkali-soluble resin, 3% by weight to 50% by weight of cross-linking agent, and 0.1% by weight to 20% of photo-acid generator.
% By weight.

The photoresist solution generally contains an alkali-soluble resin, a cross-linking agent and a photo-acid generator in a solvent of 1% by weight to 5%.
It is prepared by mixing and dissolving in a proportion of 0% by weight.

Examples of the solvent used in this case 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. can give. The above solvents may be used alone or in combination of two or more kinds. The resist composition obtained by the above method may further contain a sensitizer, a dye, an adhesion improver and the like, if necessary.

[0041]

EXAMPLES Next, 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 (a) (p-OST cyclic dimer, manufactured by Mitsui Toatsu), 50.4 g of ethyl cellosolve acetate,
Then, 6.08 g of 5% oxalic acid was charged, the temperature was raised to 80 ° C., and 13.0 g of 37% formalin was added dropwise from the dropping funnel over 60 minutes while stirring. Then, it stirred at 110 degreeC for 10 hours. Then, neutralization, washing, and dehydration were performed 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.

[0043]

[Chemical 11]

Synthesis Example 2 To 25.0 g of methyltrichloroacetimidate, 4.0 g of glacial acetic acid was added dropwise over 30 minutes while stirring at room temperature. 1 at room temperature
After stirring for an hour, the temperature was raised to 80 ° C. and kept for 24 hours. Then, the reaction solution was poured into 300 ml of water, stirred and the precipitated crystals were collected by filtration. Recrystallize from 85% ethanol, 2,
4,6-Tris (trichloromethyl) -s-triazine was obtained.

Example 1 13.3 parts of Resin A obtained in Synthesis Example 1, 1.0 part of hexamethylol melamine hexamethyl ether as a cross-linking agent, and 2,4 obtained in Synthesis Example 2 as a photoacid generator. 0.7 part of 6-tris (trichloromethyl) -s-triazine was dissolved in 45 parts of ethyl cellosolve acetate. A resist solution was prepared by filtering the prepared solution with a 0.2 μm Teflon filter. Using a spin coater on a silicon wafer that has been cleaned by a conventional method
It was applied to a thickness of 0.8 μm. The wafer was then prebaked in an oven at 100 ° C for 20 minutes. Then
Canon Proximity Mask Aligner PLA-50 with the above coating through a chrome mask having a pattern
Far UV exposure was performed using a CM-250 mirror at 1F. After exposure, place the wafer on a hot plate at 120 ° C for 1
After heating for a minute, the exposed portion was cross-linked. This was developed with a 2.00% by weight aqueous solution of tetramethylammonium hydroxide to obtain a negative pattern. Obtain the characteristic curve of exposure dose and residual film rate 5mJ / cm ² (254nm)
Sensitivity (exposure amount at 90% residual film rate) was obtained. Further, the formed pattern was observed by an electron microscope, and it was found that a fine pattern of 0.7 μm was resolved.

Example 2 Instead of hexamethylolmelamine hexamethyl ether as a crosslinking agent, 2,6-bis (hydroxymethyl) was used.
The same procedure as in Example 1 was carried out except that -p-cresol (manufactured by Aldrich) was used. A sensitivity of 15 mJ / cm ² (254 nm) was obtained. It was also found that a 0.7 μm fine pattern was resolved.

Comparative Example 1 Similar to Example 1 except that α-phenylsulfonylacetophenone (manufactured by Tokyo Kasei) was used in place of 2,4,6-tris (trichloromethyl) -s-triazine as a photoacid generator. To obtain a negative pattern. Sensitivity is 44mJ
/ Cm ² (254 nm).

Example 3 KrF excimer laser stepper having exposure wavelength of 248 nm (NSR 1755 EX8 NA = 0.4 from Nikon Corporation)
The same procedure as in Example 1 was carried out except that the exposure was performed using 5). A sensitivity of 2.3 mJ / cm ² (248 nm) was obtained.
It was also found that a 0.5 μm fine pattern was resolved.

[0049]

As described above, the negative photoresist composition of the present invention has high sensitivity and high resolution in the exposure region of the deep ultraviolet and excimer laser sources. As a result, the resolution and the contrast can be remarkably improved in the lithography using the light source, and a highly precise fine photoresist pattern can be formed. Therefore, these compositions are required to have higher sensitivity and resolution in the future IC and ultra-L
It is very useful as a resist for manufacturing integrated circuits such as SI.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/027 (72) Inventor Naoki Takeyama 3-1, Kasugadaka, Konohana-ku, Osaka-shi, Osaka No. 98 Sumitomo Chemical Co., Ltd.

Claims (2)

[Claims] 1. An alkali-soluble resin obtained by condensing a compound represented by the following general formula (1) with an aldehyde: (In the formula, R ^{1 to} R ⁹ are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted acyl group, a halogen atom, or an —OH group. And at least one of R ^{1 to} R ⁹ is a —OH group, and has at least two hydrogen atoms at the o-position or the p-position with respect to the —OH group.) Crosslinking agent and the following general formula (2 ) A photo-acid generator represented by (In the formula, R ¹⁰ , R ¹¹ and R ¹² are each independently an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted alkenyl group, or an optionally substituted aralkyl. A group, an optionally substituted piperidino group, It represents a hydrogen atom, an optionally substituted alkyl group or an optionally substituted aryl group. However, R ¹⁰ and R ¹¹
At least one of R ¹² and R ¹² represents a mono-, di- or trihalogen-substituted methyl group. Negative photoresist composition containing a). 2. The negative photoresist composition according to claim 1, wherein the crosslinking agent is a compound represented by the following general formula (3). [Chemical 3] ¹⁸ , R ²⁰ , R ²¹ , R ²² and R ²³ each independently represent a hydrogen atom, —CH ₂ OH or —CH ₂ OR ²⁴ . R ²⁴ represents an alkyl group. )