JPH0962008A - Composition for forming resist pattern and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of the dimensional precision of various patterns in a pattern forming process by incorporating a specified compd. or polymer or the compd. and polymer. SOLUTION: A compd. (a) having at least one pair of acidic and basic groups each capable of forming a stable inner salt in one molecule and/or a polymer (b) having at least one pair of acidic and basic groups each capable of forming a stable inner salt in one molecule is incorporated. The acidic group of each of the compd. (a) and the polymer (b) is, e.g. carboxylic acid, sulfonic acid, sulfinic acid, sulfenic acid or arom. hydroxyl and the basic group is, e.g. amino or imino. A combination of a carboxylic acid or sulfonic acid group with an amino groups especially preferable.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composition for forming a fine resist pattern in lithography and a method for forming a resist pattern.

[0002]

2. Description of the Related Art In recent years, with the high integration and high density of semiconductor circuits, there has been a demand for higher accuracy of pattern dimensions in a pattern forming process. The fine pattern forming method includes
A method called lithography for exposing a resist in a desired pattern shape to obtain a resist image is generally used. However, there are various precision deterioration factors in lithography, and their resolution is required. Listed below are specific causes of accuracy deterioration. (1) The accuracy of the resist image deteriorates due to the reflected light from the substrate, which deforms the dimensions and pattern shape. In particular, KrF excimer laser (248 nm),
This is a precision deterioration phenomenon that appears remarkably in optical lithography using an ArF excimer laser (193 nm) or the like. (2) The accuracy of the resist image is deteriorated due to contamination of the chemically amplified resist from the environment, which also deforms the size and pattern shape, and is particularly remarkable in the case of a positive type. (3) Accuracy deterioration due to charge-up (charging) in EB lithography, which changes the position and dimensions. Various measures have been proposed for these deterioration factors.

Regarding deterioration of the dimensional accuracy of a resist image due to interference of reflected light from a substrate, a multilayer resist (Japanese Patent Laid-Open No. 51-51) is used.
-10775, etc.), ARC (antireflection film formed under resist) method (JP-A-59-93448), ARCOR (antireflection film formed over resist) method (JP-A-62-62520). Gazette) etc. have been proposed.

Regarding the deterioration of the pattern shape of the resist image due to contamination of the chemically amplified resist from the environment, a method of forming a cover film on the resist (Proc. SPIE,
1925, 31, 1993), a method for cleaning the environment in which a resist is used (Microlithograp)
hy World, Dec. 1992, 7, 1992;
Proc. SPIE, 1925, 318, 1993; P
rc. SPIE, 2438, 599, 1995), a method of adding a base to a resist, and the like have been proposed.

Further, with respect to the deterioration of the position accuracy and the pattern dimension accuracy due to the charge-up of EB lithography,
Method for forming conductive film on resist (Japanese Patent Laid-Open No. 05-22
No. 6238) has been proposed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition for preventing deterioration of the various pattern dimensional accuracy in a pattern forming process and a pattern forming method using the same.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to further improve the accuracy deterioration of the pattern dimension due to the various causes described above, and as a result, have at least one pair of acidic group and basic group in the molecule. It has been found that the use of the compound (a) and / or the polymer (b), which have a stable salt in the molecule and have a large amount, can significantly improve the accuracy of the resist pattern.

That is, the first aspect of the present invention is to provide a compound (a) and / or a compound having at least a pair of an acidic group and a basic group in the molecule and capable of forming a stable salt in the molecule. Alternatively, for forming a resist pattern, which has at least a pair of an acidic group and a basic group in the molecule and contains a polymer (b) capable of forming a stable salt in the molecule. It relates to a composition.

The second aspect of the present invention relates to a chemically amplified resist composition containing the compound (a) and / or the polymer (b) according to claim 1, 2, 3, 4 or 5. .

The third aspect of the present invention is to A step of applying a resist (3) on the substrate (1) or on the film (2) formed on the substrate (1), and B. Claims 1, 2, 3,
A step of applying a film (4) comprising the composition according to 4 or 5 on the resist (3), and then performing heat treatment; Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern;
A step of removing the film (4) and developing the resist (3) to reveal a latent image pattern.

The fourth aspect of the present invention is to A film (4) comprising the composition according to claim 1, 2, 3, 4 or 5 is applied onto the substrate (1) or onto the film (2) formed on the substrate (1). Then, a step of performing heat treatment, and B. A step of applying a resist (3) on the film (4), and C. Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern; A step of developing the resist (3) to reveal a latent image pattern, and a method of forming a resist pattern.

Examples of the acidic group of the compound (a) and the polymer (b) include a carboxylic acid group, a sulfonic acid group, a sulfinic acid group, a sulfenic acid group and an aromatic hydroxyl group. ) And the basic group of the polymer (b) include an amino group, an imino group and the like. Among these, it is particularly preferable that the acidic group is a carboxylic acid group or a sulfonic acid group and the basic group is an amino group.

Further, as the bonding positions of these acidic group and basic group, those present on the same carbon or adjacent carbons are more preferably used so that both salts can easily form a salt. As the resist used in the third and fourth aspects of the present invention, a chemically amplified resist is particularly preferably used. Also,
When the resist used is a chemically amplified resist, a step of heat-treating the resist is usually added between steps B and C.

As the compound (a), those having the structural formulas of the following general formulas (1) to (7) are preferably used.

Embedded image (In the formula, R ^{1 to} R ⁵ are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. Is a group independently selected from the group consisting of groups, at least one of R ^{1 to} R ⁵ is an acidic group, and R ^{6 to} R ¹¹ are hydrogen, a straight or branched chain having 1 to 4 carbon atoms. It is a group independently selected from an alkyl group and a linear or branched alkoxy group having 1 to 4 carbon atoms, X is an acidic group, R ^{12 to} R ³⁶ are hydrogen, and a direct group having 1 to 4 carbon atoms. A chain or branched alkyl group, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and a halogen group, each independently selected from the group consisting of R ¹² to ³⁶ At least one is an acidic group.) Specific examples include the following.

The substituted aminobenzoic acids include aminobenzoic acids such as o-aminobenzoic acid, m-aminobenzoic acid and p-aminobenzoic acid, methoxyaminobenzoic acid, ethoxyaminobenzoic acid, n-propoxyaminobenzoic acid, iso-propoxyaminobenzoic acid, n-butoxyaminobenzoic acid, sec-butoxyaminobenzoic acid, t
-Alkoxy group-substituted aminobenzoic acids such as butoxyaminobenzoic acid, methylaminobenzoic acid, ethylaminobenzoic acid, n-propylaminobenzoic acid, iso-propylaminobenzoic acid, n-butylaminobenzoic acid, sec
-Butylaminobenzoic acid, t-butylaminobenzoic acid and other alkyl group-substituted aminobenzoic acids, hydroxy group-substituted aminobenzoic acids, nitro group-substituted aminobenzoic acids,
Examples thereof include halogen group-substituted aminobenzoic acids such as fluoroaminobenzoic acid, chloroaminobenzoic acid, and bromaminobenzoic acid. Among them, o-substituted compounds are particularly preferably used.

The aminobenzene sulfonic acids include o
-Aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, methoxyaminobenzenesulfonic acid, ethoxyaminobenzenesulfonic acid, n-propoxyaminobenzenesulfonic acid, is
Alkoxy group-substituted aminobenzene sulfonic acids such as o-propoxyaminobenzenesulfonic acid, n-butoxyaminobenzenesulfonic acid, sec-butoxyaminobenzenesulfonic acid, t-butoxyaminobenzenesulfonic acid, methylaminobenzenesulfonic acid, ethylaminobenzene Sulfonic acid, n-propylaminobenzenesulfonic acid, iso-propylaminobenzenesulfonic acid,
Alkyl group-substituted aminobenzene sulfonic acids such as n-butylaminobenzenesulfonic acid, sec-butylaminobenzenesulfonic acid and t-butylaminobenzenesulfonic acid, hydroxy group-substituted aminobenzenesulfonic acid, nitro group-substituted aminobenzenesulfonic acid, fluoro Examples include aminobenzenesulfonic acids such as halogen-substituted aminobenzenesulfonic acids such as aminobenzenesulfonic acid, chloroaminobenzenesulfonic acid, and bromoaminobenzenesulfonic acid.
-Substitutes are preferably used.

In addition, glycine, D, L-glutamic acid, D, L-glutathione, D, L-glycylglycine, D, L-alanine, γ-aminobutyric acid, γ-aminocapton, D, L-arginic acid, D, L-aspartic acid, D, L-citrulline, D, L-tryptophan,
D, L-threonine, D, L-arginine, D, L-cystine, D, L-histidine, D, L-oxyproline, D, L-isoleucine, D, L-leucine, D, L
-Lysine, D, L-methionine, D, L-ornithine,
Α-amino acids such as D, L-phenylalanine, D, L-phenylglycine, D, L-proline, D, L-serine, D, L-tyrosine, D, L-valine and their carboxylic acid groups are sulfonates. Α-Aminosulfonic acids substituted with an acid group are preferably used.

Further, amphoteric surfactants such as carboxybetaine type, sulfobetaine type, aminocarboxylic acid type, aminosulfonic acid type and imidazoline type are also preferably used.

Specific examples of the polymer (b) have at least one pair of acidic group and basic group in the molecule, and these acidic group and basic group can form a salt in the molecule. There is no particular limitation as long as it contains a repeating unit, but a compound having the structure of the compound (a) as a repeating unit is preferable. Among them, general formulas (8) to (1
A polymer containing at least 10 mol% of the repeating unit represented by 1) is preferably used.

Embedded image (In the formula, R ^{37 to} R ⁴² are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. A group independently selected from the group consisting of groups, at least one of R ^{37 to} R ⁴² is an acidic group, R ^{43 to} R ⁴⁸ are hydrogen,
It is a group independently selected from the group consisting of linear or branched alkyl groups having 1 to 4 carbon atoms. )

These polymers (b) contain 5 wt% or less of residual monomers, 10 wt% or less of oligomers having an average weight molecular weight of 1100 or less, and 10 wt% of residual salts, acids or bases.
The following are preferred. If these impurities are further reduced, the conductivity and solubility of the polymer will be improved and PE
D stability is also improved. The PED stability means that in lithography, the resist pattern image is not deformed in the elapsed time from the exposure to the baking of the resin, and the accuracy of the resist is good. From these viewpoints, the residual monomer content is 3 wt% or less and the oligomer content is 5% or less.
Less than 5% by weight of residual salts, acids and bases are preferred, less than 1% by weight of residual monomers and 2% of oligomers
% Or less, more preferably 2 wt% or less of residual salt, acid or base, 0.5 wt% or less of residual monomer, 1 of oligomer.
It is more preferable that the content of the residual salt, the acid, and the base is 1 wt% or less and the wt% or less.

The composition containing the compound (a) and / or the polymer (b) can be used as a mixture with the binder polymer (c) in order to improve the adhesion to the substrate and the film forming property. .

As the binder polymer (c), those having compatibility with the above (a) and (b) can be mentioned first. For example, a water-soluble polymer compound can be exemplified. Examples of the water-soluble polymer compound include polyvinyl alcohols such as polyvinyl alcohol, polyvinyl formal, and polyvinyl butyral, polyacrylic amides, poly (N-methylolacrylic amide), polyacrylic amides such as polyacrylic amide methylpropanesulfonic acid. , Polyvinylpyrrolidones, water-soluble alkyd resin, water-soluble melamine resin, water-soluble urea resin,
Water-soluble phenol resin, water-soluble epoxy resin, water-soluble polybutadiene resin, water-soluble acrylic resin, water-soluble urethane resin, water-soluble acrylic / styrene copolymer resin, water-soluble vinyl acetate / acrylic copolymer resin, water-soluble polyester resin, water-soluble Styrene / maleic acid copolymer resin, water-soluble fluororesin and copolymers thereof.

Further, as another example of the binder polymer (c), a polymer compound which forms an emulsion in an aqueous system can be mentioned. Examples of this include water-based alkyd resin, water-based melamine resin, water-based urea resin, water-based phenol resin, water-based epoxy resin, water-based polybutadiene resin,
Water-based acrylic resin, water-based urethane resin, water-based acrylic /
Styrene copolymer resin, water-based vinyl acetate resin, water-based vinyl acetate / acrylic copolymer resin, water-based polyester resin, water-based styrene / maleic acid copolymer resin, water-based acrylic / silica resin, water-based fluororesin and copolymers of these. To be

On the other hand, there is also one which is used as the binder polymer (c) in a form dissolved in an organic solvent. Examples of the polymer compound include acrylic or methacrylic resin, polyester resin, ethylene resin, propylene resin, vinyl acetate resin, vinyl chloride resin, ethylene-vinyl acetate resin, ethylene-vinyl chloride resin, fluororesin and these. And the like.

As the binder polymer (c), in the case of the compound (a) and the polymer (b) which are soluble in water, a water-soluble polymer compound and a polymer compound which forms an emulsion in a water system are preferably used. In the case of the compound (a) and / or the polymer (b) soluble in an organic solvent, an organic solvent type polymer compound is used. In general, the resist is often developed with an alkaline aqueous solution, and therefore a water-soluble polymer compound is the most preferable of these. These compounds (a)
The polymer (b) and the polymer (b) may be used alone, or two or more kinds may be mixed and used at an arbitrary ratio.

The ratio of the compound (a) and the polymer (b) to the binder is 10% of the compound (a) and the polymer (b).
The binder is preferably 0 to 9000 parts by weight, more preferably 0 to 5000 parts by weight, and 0 to 1 part by weight with respect to 0 parts by weight.
000 parts by weight is more preferable.

Additives such as surfactants, storage stabilizers and anti-striation agents can be used in these compositions, if necessary.

Further, the compound (a) and the polymer (b) have the effect of improving the pattern accuracy even if they are directly added to the chemically amplified resist.

Examples of the chemically amplified resist used include a resin that reacts in the presence of an acid to become alkali-soluble and a compound that generates an acid upon irradiation with ionizing radiation or a compound that promotes the generation of an acid (acid generator). And a solvent, or a compound having a function of acid-acting with an alkali-soluble resin to make it insoluble in an alkali and losing its function in the presence of an acid, an acid generator and a solvent as main components. And the like.

The effects of using each compound (a) and polymer (b) alone with the binder polymer (c) are shown in Table 1 below.

[Table 1] * ¹ : The effect of improving the accuracy of the resist image by preventing the reflected light from the substrate * ² : The effect of improving the accuracy of the resist image by preventing the contamination of the chemically amplified resist from the environment * ³ : The registration by preventing the charge-up in the EB lithography Stroke image accuracy improvement effect ◎: Significant effect ○: Effective ×: No effect

The embodiments of the present invention will be listed below. Compound (a) having at least one pair of acidic group and basic group in one molecule and capable of forming a stable salt in the molecule, and / or at least one pair of acidic group and base in the molecule A composition for forming a resist pattern, which comprises a polymer (b) having a functional group and capable of forming a stable salt in the molecule. 2. The resist pattern forming composition as described in 1 above, wherein the acidic group is a sulfonic acid group or a carboxylic acid group, and the basic group is an amino group. 3. The resist pattern forming composition as described in 1 above, wherein the bonding positions of the acidic group and the basic group are the same carbon or adjacent carbons. 4. The resist pattern forming composition as described in 1 above, wherein the compound (a) is at least one compound represented by the following general formulas (1) to (7).

Embedded image (In the formula, R ^{1 to} R ⁵ are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. Is a group independently selected from the group consisting of groups, at least one of R ^{1 to} R ⁵ is an acidic group, and R ^{6 to} R ¹¹ are hydrogen, a straight or branched chain having 1 to 4 carbon atoms. It is a group independently selected from an alkyl group and a linear or branched alkoxy group having 1 to 4 carbon atoms, X is an acidic group, R ^{12 to} R ³⁶ are hydrogen, and a direct group having 1 to 4 carbon atoms. A chain or branched alkyl group, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and a halogen group, which are independently selected from the group consisting of R ^{12 to} R ³⁶ At least one of which is an acidic group.) 5 The polymer (b) is mainly represented by the following general formula (8) to
The resist pattern-forming composition as described in 1 above, which has at least one repeating unit represented by (11).

[Chemical 6] (In the formula, R ^{37 to} R ⁴² are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. Is a group independently selected from the group consisting of groups, at least one of R ^{37 to} R ⁴² is an acidic group, R ^{43 to} R ⁴⁸ are hydrogen,
It is a group independently selected from the group consisting of linear or branched alkyl groups having 1 to 4 carbon atoms. ) 6 The polymer (b) contains 5 wt% or less of residual monomers,
10 wt% oligomer with an average weight molecular weight of 1100 or less
The resist pattern forming composition as described in the above item 1, 2, 3, 4 or 5, wherein the total amount of residual salt, acid and base is 10 wt% or less. 7. The aforementioned items 1, 2 containing a binder polymer (c),
The composition for forming a resist pattern according to 3, 4, 5 or 6. 8. The resist pattern forming composition as described in 7 above, wherein the compound (a) and / or the polymer (b) and the binder polymer (c) are all dissolved in water. 9. The resist pattern forming composition as described in 7 above, wherein the compound (a) and / or the polymer (b) and the binder polymer (c) all form an emulsion in an aqueous system. 10. The resist pattern forming composition as described in 7 above, wherein the compound (a) and / or the polymer (b) and the binder polymer (c) are all dissolved in an organic solvent. [11] A chemically amplified resist composition comprising the compound (a) and / or the polymer (b) according to the above item [1], [2], [3], [5], or [6]. 12 A. A step of applying a resist (3) on the substrate (1) or on the film (2) formed on the substrate (1), and B. A step of applying a film (4) made of the composition of claim 1, 2, 3, 4 or 5 on the resist (3), and then performing heat treatment; Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern; A step of removing the film (4) and developing the resist (3) to reveal a latent image pattern. 13 A. A film (4) comprising the composition according to claim 1, 2, 3, 4 or 5 is applied onto the substrate (1) or onto the film (2) formed on the substrate (1). Then, a step of performing heat treatment, and B. A step of applying a resist (3) on the film (4), and C. Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern; A step of developing the resist (3) to reveal a latent image pattern, and a method of forming a resist pattern. (14) A method for forming a resist pattern, wherein the resist according to (12) or (13) above is a chemically amplified resist. 15. A method for forming a resist pattern, which comprises adding a step of heat-treating a resist between the step B and the step C according to the above 12 or 13.

[0032]

EXAMPLES The present invention will be described below in greater detail by giving Examples, but the present invention is not limited to the following Examples.

Example 1 [Case of using the polymer (b)] 3-amino-4-methoxybenzenesulfonic acid 100 m
mol at 25 ° C. with stirring in a 4 mol / liter trimethylamine aqueous solution, and ammonium peroxodisulfate 1
A 00 mmol aqueous solution was added dropwise. After the dropwise addition was completed, the reaction product was further stirred at 25 ° C. for 12 hours, filtered by a centrifugal filter, washed with methyl alcohol and dried to obtain 12 g of a polymer powder having the following repeating unit. This had a volume resistance of 12.0 Ωcm.

[Chemical 7] (In the formula, X≈0.5)

10 g of the obtained polymer was suspended in a 1 mol / liter methanol solution of sulfuric acid for 30 minutes, desalted, filtered, and washed with methyl alcohol to obtain 8 g of a desalted polymer. The volume resistance of this product is 3.0 Ωcm
Met. The residual monomer contained in the desalted polymer was 3-amino-4-methoxybenzenesulfonic acid in an amount of 0.1 wt%, and the trimethylamine sulfate as a by-product salt was in an amount of 0.5 wt%. Trimethylamine forming a salt with a sulfonic acid group, which is an acidic group, is 1.0 w
It was t%. 3 parts by weight of the polymer was dissolved in 100 parts by weight of water with stirring at room temperature to prepare a conductive composition. The solution thus obtained was applied on a glass substrate by a spin coating method, and dried at 100 ° C. A film having a smooth surface resistance value of 1.0 × 10 ⁵ Ω / □ having a film thickness of 0.1 μm was obtained.

As a result of the measurement, the number average molecular weight was 150,00.
0, weight average molecular weight 190,000, Z average molecular weight 21
50,000, dispersity MW / MN 1.5, MZ / MW
1.3. 3 parts by weight of this polymer was dissolved in 100 parts by weight of water with stirring at room temperature to prepare a forming composition.

Example 2 [Case of using compound (a)] 2 parts by weight of o-aminobenzenesulfonic acid and 2 parts by weight of polyvinyl alcohol (saponification number: 89%, degree of polymerization: 500) were added to 100 parts by weight of water at room temperature. The mixture was stirred and dissolved to prepare a forming composition.

Example 3 [Case of using the compound (a)] 2 parts by weight of D-arginic acid and 2 parts by weight of polyvinyl alcohol (saponification number: 89%, degree of polymerization: 500) were dissolved in 100 parts by weight of water with stirring at room temperature. Then, a forming composition was prepared.

Example 4 A pattern was formed by the following method using the compositions of Examples 1 to 3 thus obtained. An electron beam chemical amplification type positive resist having a film thickness of 0.5 μm is applied by a spin coating method to a wafer substrate on which an oxide film 5000 Å is formed on the gate step process to form a resist film. The resist is a two-component positive resist consisting of a partially t-BOC (tert-butoxycarbonyl) -modified polyvinylphenol resin and an acid generator. 11 on the hot plate
Prebaking was performed at 0 ° C. for 100 seconds. Then, the composition for improving the pattern accuracy is applied on the resist by 0.10 μm.
Spin coating at 100 ℃ on a hot plate
Prebaking was performed for 100 seconds. The evaluation substrates coated with the compositions of Examples 1 to 3 were each subjected to an acceleration voltage of 30 kV,
Hole patterning was performed by electron beam irradiation with an electron beam exposure amount of 8 μC / cm ² . After the exposure is completed, baking is performed on a hot plate at 95 ° C. for 100 seconds. During this time, the time until baking was changed from 1 minute to 2 hours. Then, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 2 minutes using a spin developer, and then rinsed with pure water. At the same time as this development, each overcoat film can be peeled off.

Comparative Example 1 As Comparative Example 1, a sample in which the pattern forming composition was not applied to the substrate prepared in the same manner as in Example 4 was prepared.

Comparative Example 2 As Comparative Example 2, polyvinyl alcohol (saponification number 89
%, Polymerization degree 500) 3 parts by weight was dissolved in 100 parts by weight of water with stirring at room temperature to prepare a coating agent. This coating agent was applied on the substrate prepared in the same manner as in Example 4 by 0.15 μm.
m.

Comparative Example 3 As Comparative Example 3, 3 parts by weight of poly-acrylamidomethylpropanesulfonic acid (PAMPS) was dissolved in 100 parts by weight of water with stirring at room temperature to prepare a coating agent. This coating agent was formed on the substrate prepared in the same manner as in Example 4 by adding 0.
It was formed with a film thickness of 15 μm.

COMPARATIVE EXAMPLE 4 In Comparative Examples 1 to 3, the evaluation substrates were each subjected to an acceleration voltage of 30 k.
Hole patterning was performed by electron beam irradiation at V and an electron beam exposure amount of 8 μC / cm ² . After the exposure was completed, baking was performed on a hot plate at 95 ° C. for 100 seconds. During this time, the time until baking was changed from 1 minute to 30 minutes. Then, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 2 minutes using a spin developer, and then rinsed with pure water. At the same time as this development, each overcoat film can be peeled off.

Example 5 PED [exposure to post-exposure baking (PEB)] A change of 0.2 μm holes due to a difference in time was observed. In the case of using the overcoat films of Examples 1 to 3, the pattern variation was within 5% even after 2 hours. It was confirmed that although the solution was acidic, it had little effect on the resist pattern and had a high PED stabilizing effect. FIG. 1 shows an SEM photograph immediately after exposure for pattern formation after overcoating a resist with the composition of Example 1 in Example 4. Figure 2 shows the SEM photograph after baking 2 hours after exposure.
It was shown to. No change was observed in the shape of the contact hole immediately after the exposure and after the completion of baking 2 hours later.

Comparative Example 5 As in Example 5, changes in 0.2 μm holes due to differences in PED (exposure to PEB) time were observed. When the PED time was set to 5 minutes, the pattern (hole type) without the overcoat film (Comparative Example 1) was 25% smaller than the pattern with 1 minute. After being left for another 30 minutes, the surface was not dissolved in the developing solution and the pattern could not be resolved. FIG. 3 shows a SEM photograph of Comparative Example 1 immediately after exposure, and FIG. 4 shows a photograph after 30 minutes. In the case of using PVA for the coating film (Comparative Example 2), the surface was hardly dissolved by PED for 30 minutes. The trace of the pattern was slightly visible, and the resolution was not reached. It can be seen that the PED stabilizing film is insufficient. When PAMPS acid was used for the overcoat (Comparative Example 3), the resist film thickness after development was reduced by 40% with respect to the film thickness at the time of coating, and became 0.3 μm. It seems that the acid in the coating film promoted the positive reaction and dissolved during development. It can be seen that the effect on the resist is great.

Example 6 The effect of preventing misalignment due to electrification of the composition prepared in Example 1 was investigated. The gate step was evaluated by measuring the alignment accuracy of the hole pattern. With the resist alone (the substrate of Comparative Example 1), a positional deviation of 0.15 μm at maximum due to charging occurred. When the composition prepared in Example 1 was used, the shift amount was 0.05 μm at maximum.

Example 7 The overcoat film formed from the composition of Example 1 was effective as an antistatic film. That is, the same resist as in Example 4 was formed to a thickness of 1 μm on a quartz substrate having a thickness of 1 mm. The composition of Example 1 was overcoated with a thickness of 0.05 μm and the composition was not overcoated to form a pattern under the same conditions as in Example 4, and the antistatic effect thereof was examined. The results are shown in FIGS. When the composition of Example 1 was used (FIG. 5), a pattern as designed without misalignment and dimensional error was formed, but when there was no overcoat (FIG. 6), significant misalignment and dimensional error were observed. Was done.

Example 8 The antistatic effect of the chemically amplified negative and the effect on the resist were evaluated. Using the composition for pattern formation prepared in Example 1, a pattern was formed by the following method. A chemically amplified negative resist (SAL-601; manufactured by Shipley) having a film thickness of 2.0 μm is applied on a silicon wafer substrate by a spin coating method to form a resist film. Prebaking was performed on a hot plate at 115 ° C. for 100 seconds. Then, the composition for improving pattern accuracy of Example 1 was spin-coated on the resist to a film thickness of 0.05 μm, and prebaked at 80 ° C. for 100 seconds on a hot plate. Accelerating voltage 3
Patterning was carried out by patterning 2.0 μm lines and spaces by electron beam irradiation on the entire surface of the chip at 0 kV and an electron beam exposure amount of 25 μC / cm ² . After the exposure is completed, baking is performed on a hot plate at 85 ° C. for 100 seconds. Then, the resist is developed with a 4.1 wt% tetramethylammonium hydroxide aqueous solution for 5 minutes using a spin developer. Simultaneously with this development, the conductive film was peeled off and rinsed with pure water. I confirmed the line connection in the field connection. A shift of 0.2 μm occurred between the fields only with the resist, whereas it was within 0.04 μm when the composition of Example 1 was used. From this, it can be seen that the composition of the present invention is an overcoat material having an antistatic effect without affecting the pattern.

Comparative Example 6 As a comparative example, a sulfonic acid group-substituted polyisothianaphthene (synthesized by the method disclosed in Japanese Patent Application Laid-Open No. 07-41756) was used as an overcoat film on the same resist in an amount of 0.05.
A film having a thickness of μm was applied and baked in the same manner. Pattern formation was performed by the same method as in Example 8. Even when sulfonic acid group-substituted polyisothianaphthene was used, the gap between the fields was within 0.04 μm, and the antistatic effect was confirmed. However, due to the influence of the acid in the overcoat film, the resist was crosslinked and many of the patterns were short-circuited, resulting in poor resolution.

Example 9 An electron beam chemical amplification type positive resist was applied. Using the composition for pattern formation prepared in Example 1, a pattern was formed by the following method. A chemically amplified positive resist having a film thickness of 0.7 μm is applied on the wafer substrate having the oxide film 5000 Å formed thereon by spin coating to form a resist film. Prebaking was performed on a hot plate at 130 ° C. for 100 seconds. Then, the conductive composition for pattern formation of Example 1 was spin-coated on the resist to a film thickness of 0.10 μm, and prebaked at 130 ° C. for 100 seconds on a hot plate. And acceleration voltage 30kV, electron beam exposure 8μ
Hole patterning was performed by electron beam irradiation at C / cm ² . After the exposure is completed, use a hot plate at 95 ° C.
Bake for 100 seconds. Then, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 2 minutes using a spin developer, and then rinsed with pure water. By using the overcoat film, positional deviation due to charging can be prevented, and at the same time, even when the time from exposure to PEB is 2 hours, the insolubilized layer is not formed and a highly accurate pattern can be formed.
At the same time as this development, the conductive film can be peeled off.

Example 10 A PED stabilizing film was applied to an excimer chemically amplified positive resist. Using the composition for pattern formation prepared in Example 1, a pattern was formed by the following method. A chemically amplified positive resist having a film thickness of 0.7 μm is applied on the wafer substrate having the oxide film 5000 Å formed thereon by spin coating to form a resist film. The resist is a three-component positive resist whose main resin is vinylphenol. Prebaking was performed on a hot plate at 100 ° C. for 100 seconds. Then, the composition for an overcoat film was spin-coated on the resist to a film thickness of 0.10 μm, and prebaked at 100 ° C. for 100 seconds on a hot plate. Exposure with KrF excimer light is performed. Exposure 30m
Hole patterning was performed at J / cm ² . After the exposure is completed, baking (PEB) is performed on a hot plate at 95 ° C. for 100 seconds. Then, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 1 minute using a spin developer, and then rinsed with pure water. At the same time as this development, the coat film can be peeled off. By using the overcoat film, it was possible to form a highly accurate pattern without forming an insolubilized layer even when the time from the start of exposure to PEB was 2 hours.

Example 11 Excimer chemical amplification system negative resist (XP8, Shipley Co.)
9131) Applied as an overcoat antireflection film. Example 1
A pattern was formed by the following method using the composition for pattern formation prepared in the above, to which a polyethylene glycol-based surfactant was added. A chemically amplified negative resist for excimer light having a thickness of 0.8 μm is formed on a wafer substrate on which a metal substrate for wiring is formed by a spin coating method.
89131) is applied to form a resist film. Prebaking was performed on a hot plate at 100 ° C. for 100 seconds. Then, the composition for an overcoat film was spin-coated on the resist as an overcoat antireflection film to a film thickness of 0.10 μm, and prebaked at 100 ° C. for 100 seconds on a hot plate. Exposure with KrF excimer light is performed.
The hole pattern was formed under the condition of the exposure amount of 50 mJ / cm ² . After the exposure is completed, baking (PEB) is performed on a hot plate at 95 ° C. for 100 seconds. Then, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 1 minute using a spin developer, and then rinsed with pure water. At the same time as this development, the coat film can be peeled off. By using the overcoat film, the influence of reflection, which is a problem of short wavelength light, was suppressed, and highly precise pattern formation was possible.

Example 12 An antistatic agent was applied to an electron beam chemically amplified negative resist on a mask substrate. Using the composition for pattern formation prepared in Example 1, a pattern was formed by the following method.
Chemically amplified negative resist (Hitachi Kasei RE4210N) with a film thickness of 0.5 μm on a mask substrate by spin coating.
-21) was applied to form a resist film, and prebaking was performed on a hot plate at 110 ° C. for 100 seconds. The conductive composition for forming a pattern is formed on the resist by 0.0
8 μm on a hot plate by spin coating with a film thickness of 5 μm
Prebaking was performed at 0 ° C. for 100 seconds. Then, patterning was performed by electron beam irradiation at an acceleration voltage of 20 kV and an electron beam exposure amount of 10 μC / cm ² . After the exposure is finished,
The upper antistatic film is peeled off by washing with water. 30 by dropping pure water
Second wash, then spin off at 4000 rpm for 30 seconds,
The water was dried. As a post-exposure bake of the resist, a hot plate is used to bake at 105 ° C. for 8 minutes. Next, the resist was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 5 minutes using a spin developer, and then rinsed with pure water. At the same time as this development, the conductive film can be peeled off. Despite being on the mask substrate
The gap due to charge-up has been reduced. Furthermore, it was confirmed that the upper antistatic film formed a good pattern without adversely affecting the shape and resolution of the resist pattern.

Example 13 A halftone mask was applied. Using the composition for pattern formation prepared in Example 1, a pattern was formed by the following method. Chromium oxide 100Å is formed on a quartz substrate to form a halftone max substrate. A 0.4 μm-thick chemically amplified negative resist was applied on the mask substrate by a spin coating method to form a resist film, and prebaking was performed on a hot plate at 110 ° C. for 100 seconds. Then, the conductive composition for pattern formation was spin-coated on the resist to a film thickness of 0.05 μm, and prebaked at 110 ° C. for 100 seconds on a hot plate. Patterning was performed by electron beam irradiation at an acceleration voltage of 20 kV and an electron beam exposure amount of 10 μC / cm ² . After the exposure is completed, baking is performed on a hot plate at 95 ° C. for 8 minutes. Then, the resist is developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution using a spin developer. At the same time as this development, the conductive film can be peeled off. The development was performed by a dip method for 2 minutes and then rinsed with pure water. Despite being on the mask substrate, the deviation due to charge-up was reduced. Furthermore, it was confirmed that the upper antistatic film formed a good pattern without adversely affecting the shape and resolution of the resist pattern.

Application as an Antistatic Film to Example 14 [Non-Chemically Amplified Positive Resist] A material obtained by adding a surfactant (polyoxyethylene octyl phenyl ether) to the composition for pattern formation prepared in Example 1 was used. A pattern was formed by the following method. Formed Al 8000Å, and further polysilicon 1
An acrylic resist (OEBD-1) having a film thickness of 1.8 μm was formed on a wafer substrate having a thickness of 000 Å by spin coating.
00 Tokyo Ohka Co., Ltd.) is applied to form a resist film.
Prebaking was performed on a hot plate at 80 ° C. for 100 seconds. Then, the conductive composition for pattern formation was spin-coated on the resist to a film thickness of 0.05 μm, and prebaked at 80 ° C. for 100 seconds on a hot plate. Then, patterning was performed by electron beam irradiation at an accelerating voltage of 30 kV and an electron beam exposure amount of 70 μC / cm ² . Rinse with pure water for 50 seconds using a spin developer to remove the antistatic film, and then develop the resist with MIBK. Despite the thick resist film thickness and high exposure dose, the deviation due to charge-up was reduced. Furthermore, it was confirmed that the upper antistatic film formed a good pattern without adversely affecting the shape and resolution of the resist pattern.

Application as an Antistatic Film to Example 15 [Non-Chemical Amplification Novolak] The composition for pattern formation prepared in Example 1 was used to form a pattern by the following method. A film thickness of 1.5μ is spin-coated on a wafer with an oxide film of 7000Å.
m novolak-based resist (manufactured by OFPR Tokyo Ohka) is applied to form a resist film. 1 on the hot plate
Baking was performed at 00 ° C. for 100 seconds. Then, the resist composition was spin-coated with a film thickness of 0.05 μm, and prebaked at 80 ° C. for 100 seconds on a hot plate. Acceleration voltage 40kV, electron beam exposure 80μ
A pattern was formed by electron beam irradiation at C / cm ² .
After developing with tetramethylammonium hydroxide 2.38 wt% for 50 seconds using a spin developer,
Pure and rinsed. During this development, the antistatic film can be peeled off at the same time. It was confirmed that the displacement caused by the charge-up was reduced.

Example 16 [Addition to chemically amplified positive resist] 0.05 parts of o-aminobenzenesulfonic acid was added to 100 parts by weight of the chemically amplified positive resist used in Example 4.
Parts by weight was added. When a pattern was formed by the same method as in Comparative Example 5, the hole pattern diameter of the non-added one was reduced by 25% at the PED time of 5 minutes.
With the addition of aminobenzene sulfonic acid, the hole pattern diameter decreased by 25% when left for 30 minutes. Thus, the addition of o-aminobenzenesulfonic acid improved the PED stability.

[0057]

By using the resist pattern accuracy improving composition and the resist pattern accuracy improving method of the present invention in the lithographic technique, it is possible to form a highly precise fine pattern, and thereby to improve the yield in semiconductor manufacturing. improves. The composition for improving the accuracy of the resist pattern has the ability to prevent light reflection in photolithography by itself, and by blending it with a resist, particularly a chemically amplified resist, or by using it as a layer overlaid with a resist layer. It exhibits anti-reflection and anti-static properties, and also prevents chemically amplified resists from being contaminated from the environment. As a result, resist image deformation and misalignment are prevented, greatly improving resist accuracy. did.

[Brief description of drawings]

FIG. 1 shows S immediately after exposure for micropattern formation by the method of Example 4 using the composition of Example 1
An EM photograph is shown.

FIG. 2 shows an SEM photograph taken after baking the one shown in FIG. 1 for 2 hours after exposure.

FIG. 3 shows S immediately after exposure for micropattern formation by the method of Example 4 using the composition of Comparative Example 1
An EM photograph is shown.

FIG. 4 shows an SEM photograph taken after baking of FIG. 3 for 2 hours after exposure.

FIG. 5 is a photograph showing an antistatic effect when an overcoat layer of Example 6 is provided.

FIG. 6 is a photograph showing the effect of charging in the case where there was no overcoat layer in Example 6.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01L 21/027 H01L 21/30 502R 569F (72) Inventor Masami Yuasa Oguro Town, Tsurumi Ward, Yokohama City, Kanagawa Prefecture 10-1 Nitto Chemical Industry Co., Ltd. Central Research Institute (72) Inventor Masashi Uzawa 10-1 Daikokucho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Nitto Chemical Industry Co., Ltd. Central Research Institute (72) Inventor Keiko Yano Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi FUJITSU LIMITED (72) Inventor Takashi Maruyama 1015 Kamikotanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Kanagawa Prefecture Within Fujitsu Limited (72) Inventor Keiji Watanabe 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Stock Association The inner

Claims (8)

[Claims] 1. A compound (a) having at least one pair of acidic group and basic group in the molecule and capable of forming a stable salt in the molecule, or at least one pair of acidic group in the molecule. And a polymer (b) having a basic group and capable of forming a stable salt in the molecule, or containing the compound (a) and the polymer (b). A composition for resist pattern formation. 2. The resist pattern forming composition according to claim 1, wherein the acidic group is a sulfonic acid group or a carboxylic acid group, and the basic group is an amino group. 3. The resist pattern forming composition according to claim 1, wherein the bonding positions of the acidic group and the basic group are the same carbon or adjacent carbons. 4. The compound (a) is represented by the following general formula (1) to
The resist pattern-forming composition according to claim 1, which is at least one compound represented by (7). Embedded image (In the formula, R ^{1 to} R ⁵ are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. Is a group independently selected from the group consisting of groups, at least one of R ^{1 to} R ⁵ is an acidic group, and R ^{6 to} R ¹¹ are hydrogen, a straight or branched chain having 1 to 4 carbon atoms. It is a group independently selected from an alkyl group and a linear or branched alkoxy group having 1 to 4 carbon atoms, X is an acidic group, R ^{12 to} R ³⁶ are hydrogen, and a direct group having 1 to 4 carbon atoms. A chain or branched alkyl group, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and a halogen group, which are independently selected from the group consisting of R ^{12 to} R ³⁶ At least one of which is an acidic group.) 5. The resist pattern forming composition according to claim 1, wherein the polymer (b) has at least one repeating unit represented by the following general formulas (8) to (11). Embedded image (In the formula, R ^{37 to} R ⁴² are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, a hydroxyl group, a nitro group and halogen. Is a group independently selected from the group consisting of groups, at least one of R ^{37 to} R ⁴² is an acidic group, R ^{43 to} R ⁴⁸ are hydrogen,
It is a group independently selected from the group consisting of linear or branched alkyl groups having 1 to 4 carbon atoms. ) 6. The compound (a) or polymer (b) according to claim 1, 2, 3, 4 or 5, or the compound (a) and the polymer (b). Chemically amplified resist composition. 7. A. A step of applying a resist (3) on the substrate (1) or on the film (2) formed on the substrate (1), and B. A compound (a) having at least one pair of acidic group and basic group in the molecule and capable of forming a stable salt in the molecule, or at least one pair of acidic group and basic group in the molecule. For forming a resist pattern, which has a polymer (b) which is capable of forming a stable salt in the molecule, or contains the compound (a) and the polymer (b). A step of applying a film (4) made of the composition on the resist (3), and then performing heat treatment; Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern; D. A step of removing the film (4) and developing the resist (3) to reveal a latent image pattern. 8. A. On the substrate (1) or on the film (2) formed on the substrate (1), there are at least one pair of acidic group and basic group in the molecule, and these are stable in the molecule. Compound (a) capable of forming a salt or polymer (b) having at least a pair of acidic group and basic group in the molecule and capable of forming a stable salt in the molecule Alternatively, a step of applying a film (4) made of a resist pattern forming composition containing the compound (a) and the polymer (b), and then performing heat treatment, and B. Applying a resist (3) on the film (4), and C. Exposing the resist (3) with ionizing radiation that penetrates the film (4) to form a latent image pattern; D. A step of developing the resist (3) to reveal a latent image pattern, and a method of forming a resist pattern.