JP2001022084A - Fine pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the refractive index and absorbancy index of an antireflection film and to make the antireflection film thin by selecting the kinds and contents of components constituting the antireflection film. SOLUTION: When a photoresist film laminated on a substrate by way of an organic antireflection film is imagewise exposed and developed to form a fine pattern, the refractive index and absorbancy index of the organic antireflection film are adjusted in such a way that the allowable range of film thickness which produces a variation of 0.01 in the vicinity of the minimum reflectance becomes ±0.01 μm in a graph drawn by plotting the thickness of the organic antireflection film as the x-axis and reflectance on the interface between the organic antireflection film and the photoresist film as the y-axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a photoresist film laminated on a substrate via an organic anti-reflection film, after image formation exposure, and developing the photoresist film. The present invention relates to a method for forming a fine pattern using an organic anti-reflection film which has been reduced in thickness.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and multi-layering of ICs, LSIs and liquid crystal display elements, the influence of standing waves due to exposure actinic rays has become a major obstacle when forming fine patterns by lithography. . For this reason, an organic anti-reflection film is interposed between the substrate and the photoresist layer to suppress the effect of standing waves. The demand for thinner films is increasing. Heretofore, as a method of forming an anti-reflection film, a method of forming an anti-reflection film mainly composed of an amorphous carbon film on a substrate surface by vapor deposition (Japanese Unexamined Patent Application Publication No.
No. 8248) and a method of irradiating ultraviolet rays when forming an organic antireflection film to adjust the optical characteristics of the antireflection film (Japanese Patent Application Laid-Open No. 8-37140). In such a case, it is difficult to reduce the thickness of the antireflection film required at present and to completely suppress the standing wave.

[0003]

SUMMARY OF THE INVENTION According to the present invention, the refractive index (n) and the extinction coefficient (k) of the antireflection film are adjusted by selecting the type and content of the components constituting the antireflection film. The purpose of the present invention is to reduce the thickness of the prevention film.

[0004]

Means for Solving the Problems The inventors of the present invention have found that, for a number of organic antireflection film materials having different refractive indices (n) and extinction coefficients (k), the film thickness when an antireflection film is formed; When the relationship between the reflectance at the interface between the antireflection film and the photoresist film was examined, the minimum point of the reflectance moved to the smaller thickness as the refractive index increased, and this tendency showed that the absorption coefficient was different. The present inventors have found that there is no difference, and have made the present invention based on this finding.

That is, the present invention provides a method for forming a fine pattern by subjecting a photoresist film laminated on a substrate via an organic anti-reflection film to image formation exposure and then performing development processing to form a fine pattern. In a graph in which the thickness of the antireflection film is plotted on the horizontal axis and the reflectance at the interface between the organic antireflection film and the photoresist film is plotted on the vertical axis, a fluctuation value 0.01 occurs near the minimum point of the reflectance. An object of the present invention is to provide a method for forming a fine pattern, which comprises adjusting the refractive index and the extinction coefficient of an organic antireflection film so that the allowable range of the film thickness is within ± 0.01 μm.

FIG. 1 is a model diagram for explaining the structure of the method of the present invention, wherein the thickness of the organic anti-reflection film is x, and the reflectance at the interface between the organic anti-reflection film and the photoresist film is y. It is a graph which shows the relationship at the time. In the present invention, when the minimum point of the reflectance is y ₁ and the film thickness of the organic antireflection film corresponding to y ₁ is x ₁ , the intersection points P and Q of the line Y of y ₁ +0.01 and the graph are obtained. X ₂ and x ₃ corresponding to x ± 0.
The refractive index (n) and the extinction coefficient (k) of the organic antireflection film are adjusted so as to fall within the range of 01.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate and the photoresist in the present invention can be arbitrarily selected from those conventionally used for forming fine patterns. That is, silicon can be used as the substrate, and any photoresist, whether negative or positive, can be used as long as it can be developed using an alkaline aqueous solution. Examples of such a resist include a positive resist containing a naphthoquinonediazide compound and a novolak resin,
Positive resists containing a compound that generates an acid upon exposure, a compound that decomposes by acid to increase its solubility in an aqueous alkaline solution, and a positive resist containing an alkali-soluble resin, a compound that generates an acid upon exposure, and a compound that decomposes with an acid and dissolves in an aqueous alkaline solution There is a positive resist containing an alkali-soluble resin having a group that increases, a compound that generates an acid upon exposure, a crosslinking agent, a negative resist containing an alkali-soluble resin, and the like, but not necessarily limited to these. Absent.

Next, the material for forming the organic reaction preventing film used in the present invention is not particularly limited, and it can be arbitrarily selected from those conventionally used as materials for forming an antireflection film. . Examples of such an antireflection film-forming material include those containing a high light-absorbing substance and a crosslinking agent, those containing a high light-absorbing substance and a binder resin, and those containing a high light-absorbing substance, a crosslinking agent and a binder resin. And the like.

The high light-absorbing substance used here is a benzophenone-based compound, a diphenylsulfone-based compound, a diphenylsulfoxide-based compound, a naphthalene-based compound, or an anthracene-based compound which is generally used as an ultraviolet absorber. Can be arbitrarily selected from those having a substituent capable of crosslinking with the crosslinking agent. Examples of such a benzophenone compound include 2,2.
2 ', 4,4'-tetrahydroxybenzophenone, 2
-Hydroxy-4'-dimethylaminobenzophenone,
2,4-dihydroxy-4'-dimethylaminobenzophenone, 2,4-dihydroxy-4'-diethylaminobenzophenone, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (dimethylamino) benzophenone, etc. Examples of the diphenyl sulfone-based compound include bis (2,4-dihydroxyphenyl) sulfone, bis (3,4-dihydroxyphenyl) sulfone,
Bis (3,5-dihydroxyphenyl) sulfone, bis (3,6-dihydroxyphenyl) sulfone, bis (4
-Hydroxyphenyl) sulfone, bis (3-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-)
Examples of diphenylsulfoxide-based compounds include bis (2,3-dihydroxyphenyl) sulfoxide, bis (5-chloro-
2,3-dihydroxyphenyl) sulfoxide, bis (2,4-dihydroxyphenyl) sulfoxide, bis (2,4-dihydroxy-6-methylphenyl) sulfoxide, bis (5-chloro-2,4-dihydroxyphenyl) sulfoxide, Bis (2,5-dihydroxyphenyl) sulfoxide, bis (3,4-dihydroxyphenyl) sulfoxide, bis (3,5-dihydroxyphenyl) sulfoxide, bis (2,3,4-trihydroxyphenyl) sulfoxide, bis (2 , 3,4-Trihydroxy-6-methylphenyl) sulfoxide, bis (5-chloro-2,3,4-trihydroxyphenyl)
Sulfoxide, bis (2,4,6-trihydroxyphenyl) sulfoxide, bis (5-chloro-2,4,6-
Examples of naphthalene-based compounds include 1-naphthol, 2-naphthol, naphthalene diol, naphthalene triol, and the like.
1-naphthalenemethanol, 2-naphthalenemethanol, 1- (2-naphthyl) ethanol, naphthalenecarboxylic acid, 1-naphthol-4-carboxylic acid, 1,8-naphthalenedicarboxylic acid, naphtholsulfonic acid, etc.
Examples of anthracene-based compounds include 1-hydroxyanthracene, 9-hydroxyanthracene,
2-dihydroxyanthracene, 1,5-dihydroxyanthracene, 9,10-dihydroxyanthracene,
1,2,3-trihydroxyanthracene, 1,2,2
3,4-tetrahydroxyanthracene, 1,2,3
4,5,6-hexahydroxyanthracene, 1,2,2
3,4,5,6,7,8-octahydroxyanthracene, 1-hydroxymethylanthracene, 9-hydroxymethylanthracene, 9-hydroxyethylanthracene, 9-hydroxyhexylanthracene, 9-hydroxyoctylanthracene, 9,10- Dihydroxymethylanthracene, 9-anthracenecarboxylic acid, glycidylated anthracenecarboxylic acid, glycidylated anthracenylmethylalcohol, anthracenylmethylalcohol and polycarboxylic acids such as oxalic acid, malonic acid, methylmalonic acid, ethylmalonic acid, Examples thereof include condensation products with dimethylmalonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, glutaric acid, adipic acid, and pimelic acid. These highly light-absorbing substances may be used alone or in combination of two or more.

As the crosslinking agent, those having a functional group capable of forming a crosslink between themselves or a highly absorbent substance and / or a binder resin used together by heating, for example, a hydroxyalkyl group or an alkoxyalkyl Nitrogen-containing compounds having at least two amino groups substituted with a group or both are exemplified.
Examples of such compounds include melamine, urea, guanamine, benzoguanamine, glycoluril, succinylamide, ethylene urea, and the like, in which the hydrogen atom of the amino group is substituted with a methylol group or an alkoxymethyl group or both. . These nitrogen-containing compounds are obtained by reacting melamine, urea, guanamine, benzoguanamine, glycoluril, succinylamide, ethylene urea, etc. with formalin in boiling water to form methylol, or further adding methanol, ethanol, n- It can be easily produced by reacting a lower alcohol such as propanol or isopropanol for alkoxylation.

Among these nitrogen-containing compounds, the compounds represented by the general formula

Embedded image (A in the formula represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a —NR ¹ R ² group, and R ¹ , R ² , R ³ ,
R ⁴ , R ⁵ and R ⁶ are the same or different and each represent a hydrogen atom, a methylol group or an alkoxymethyl group, but 4 to 6 R ¹ , R ² ,
At least two of R ³ , R ⁴ , R ⁵ and R ⁶ are a methylol group or an alkoxymethyl group), which is advantageous because of good crosslinking reactivity. The melamine derivative in the compound represented by the general formula preferably has an average of 3 to less than 6 methylol groups or alkoxymethyl groups per melamine ring. As such a melamine derivative, a commercially available melamine ring 1 Mx-750 in which 3.7 methoxymethyl groups are substituted on average,
Mw-30 in which 5.8 methoxymethyl groups are substituted on average per melamine ring (both manufactured by Sanwa Chemical Co., Ltd.), and benzoguanamine derivatives include Cymel series (manufactured by Mitsui Cyanamid). Also,
These compounds may be used as dimers or trimers. In the present invention, the crosslinking agent may be used alone, or two or more kinds may be used in combination.

On the other hand, examples of the binder resin include polyamic acid, polysulfone, halogenated polymer, polyacetal, acetal copolymer, α-substituted vinyl polymer, polyamic acid, polybutenesulfonic acid, and acrylic resin. Acrylic resins having at least one acrylate unit are preferred. As the acrylic resin, for example, a polymer obtained by polymerizing an alkyl acrylate such as glycidyl acrylate, methyl acrylate, ethyl acrylate, or propyl acrylate, 4- (4-hydroxyphenyl) sulfonylphenyl acrylate, and a corresponding methacrylate is preferable. .
Examples of such a polymer include polyglycidyl acrylate, polymethyl acrylate, polyethyl acrylate, poly [4- (4-hydroxyphenyl) sulfonylphenyl acrylate], a copolymer of glycidyl acrylate and methyl acrylate, and a corresponding methacrylate. Examples thereof include a polymer and a copolymer. Among these, a weight ratio of glycidyl methacrylate to methyl methacrylate of 2: 8 to 8: 2,
Particularly, a copolymer of 3: 7 to 7: 3 or poly [4- (4
-Hydroxyphenyl) sulfonylphenyl methacrylate] is advantageous in that an intermixing layer is not easily generated between the resist film and the resist film formed on the antireflection layer. Further, the above-mentioned resin, the above-mentioned high light-absorbing substance bonded via a cross-linking agent, for example, the benzophenone-based compound, diphenylsulfone-based compound, diphenylsulfoxide-based compound, naphthalene-based compound to glycidylated polymethyl methacrylate Alternatively, a compound to which an anthracene compound is bonded can be used.

The antireflection film forming material used in the present invention includes:
In addition to the above-mentioned high light-absorbing substances and crosslinking agents and binder resins, if necessary, compatible known additives such as acetic acid, oxalic acid, maleic acid, o-hydroxybenzoic acid, 3,5-dinitro acid Addition of an organic acid such as benzoic acid, 2,6-dihydroxybenzoic acid, or SAX (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.) which is commercially available as a copolymer of o-hydroxybenzoic acid and p-xylene Can be.

The antireflection film is prepared by dissolving, for example, the above-mentioned high light-absorbing substance, a cross-linking agent and a binder resin and various additives, if necessary, in an appropriate solvent to prepare a solution, and applying the solution on a substrate. It can be formed by drying. As the solvent at this time, for example, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone,
Methyl isoamyl ketone, 2-heptanone, 1,1,1
Ketones such as trimethylacetone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, or their monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl Polyhydric alcohols such as ethers and derivatives thereof, cyclic ethers such as dioxane, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, Esters such as ethyl ethoxypropionate are used. These may be used alone or as a mixture of two or more.

Further, a surfactant may be added to the antireflection film forming solution, if desired, in order to improve coating properties and prevent striation. Examples of such a surfactant include Surflon SC-103 and SR
-100 (manufactured by Asahi Glass Co., Ltd.), EF-351 (manufactured by Tohoku Fertilizer Co., Ltd.), Florard Fc-431, Florard Fc-13
5, Florard Fc-98, Florard Fc-430,
Fluorinated surfactants such as Florad Fc-176 (manufactured by Sumitomo 3M) can be used. The amount of addition in this case is 20
It is preferable to select in the range of less than 00 ppm.

Particularly preferable as the material for forming the antireflection film is a material containing a highly light-absorbing substance such as an ultraviolet absorber, a crosslinking agent and a binder resin. In this case, as a blending ratio, in the case of containing a high light-absorbing substance and a cross-linking agent, the cross-linking agent is 10 to 300 parts by weight, preferably 20 to 200 parts by weight, based on 100 parts by weight of the high light-absorbing substance. Is selected, and in the case of containing a high light-absorbing substance, a crosslinking agent and a binder resin, the binder resin 1 to 100 parts by weight of the total amount of the high light-absorbing substance and the crosslinking agent
The range is 400 parts by weight, preferably 5 to 300 parts by weight. Further, in the case of containing a high light-absorbing substance and a binder resin, 1 to 200 parts by weight of the high light-absorbing substance, preferably 5 to 1 part by weight, per 100 parts by weight of the binder resin.
It is advantageous to blend in the range of 50 parts by weight. If the mixing ratio of the high light-absorbing substance to the crosslinking agent or the binder resin is out of the above range, the effect of suppressing the reflected light from the substrate becomes insufficient.

In the present invention, an inorganic or organic acid having a sulfur-containing acid residue can be blended. Examples of the inorganic acid having a sulfur-containing acid residue include sulfuric acid, sulfurous acid, and thiosulfuric acid, with sulfuric acid being particularly preferred. On the other hand, examples of the organic acid having a sulfur-containing acid residue include an organic sulfonic acid, an organic sulfate, an organic sulfite, and the like. In particular, an organic sulfonic acid, for example, a general formula R ⁷ -X (II) (wherein of R ⁷ is a hydrocarbon group not having or having a substituent, X is a compound represented by a is) sulfonic acid group is preferable.

In the general formula (II), the hydrocarbon group of R ⁷ preferably has 1 to 20 carbon atoms. The hydrocarbon group may be a saturated or unsaturated hydrocarbon group. It may be any of a chain, a branch, and a ring. As the substituent, for example, a halogen atom such as a fluorine atom, a sulfonic acid group, a carboxyl group, a hydroxyl group,
Examples thereof include an amino group and a cyano group, and one or more of these substituents may be introduced.

The hydrocarbon group for R ⁷ is an aromatic hydrocarbon group,
For example, a phenyl group, a naphthyl group, an anthryl group and the like may be used, and among these, a phenyl group is particularly preferable. The aromatic ring of these aromatic hydrocarbon groups has 1 carbon atom.
One to twenty alkyl groups may be bonded. The hydrocarbon group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear, branched or cyclic. In addition, this aromatic ring is a halogen atom such as a fluorine atom, a sulfonic acid group,
It may be substituted with one or more substituents such as a carboxyl group, a hydroxyl group, an amino group and a cyano group. As such an organic sulfonic acid, nonafluorobutanesulfonic acid, methanesulfonic acid, dodecylbenzenesulfonic acid, or a mixture thereof is particularly preferable from the viewpoint of improving the shape of the lower portion of the resist pattern.

The above-mentioned inorganic acids and organic acids may be used alone or in combination of two or more. The amount of the crosslinking agent varies depending on the type of acid used.
It is usually selected in the range of 0.1 to 10 parts by weight, preferably 1 to 8 parts by weight based on 00 parts by weight.

In the present invention, the material for forming an antireflection film is applied on a substrate such as a silicon wafer by using a conventional application means such as a spinner, dried, and then dried at a temperature of 150 to 300 ° C. The antireflection film is formed by heating at a temperature of.

Next, a suitable photoresist film laminated via the antireflection film thus formed is (A) a phenolic hydroxyl group-containing alkali-soluble resin and a part of the hydroxyl group of the resin with respect to an acid. And at least one resin selected from alkali-insoluble resins protected by an inert substituent, (B) an acid generator, and (C) a crosslinkable compound.

Examples of the phenolic hydroxyl group-containing alkali-soluble resin of the component (A) include various novolak resins and polyhydroxystyrene resins. Examples of the novolak resin include phenol, m-cresol, p-cresol, o-cresol, 2,3-xylenol, 2,5-xylenol,
3,5-xylenol, 3,4-xylenol, 2,
A compound obtained by condensing a phenolic compound such as 3,5-trimethylphenol or 2,3,5-triethylphenol with an aldehyde such as formaldehyde, paraformaldehyde or trioxane by a conventional method in the presence of an acidic catalyst. is there. The novolak resin preferably has a weight-average molecular weight of 2,000 to 30,000. If the weight-average molecular weight is less than 2,000, the residual film ratio decreases and the resist pattern shape deteriorates.
If it exceeds 0000, the resolution deteriorates.

On the other hand, the polyhydroxystyrene resin is
Examples thereof include a homopolymer of hydroxystyrene, a copolymer of hydroxystyrene and another styrene-based monomer, and a copolymer of hydroxystyrene with acrylic acid, methacrylic acid, or a derivative thereof. Here, as other styrene monomers, for example, styrene, p-methylstyrene,
α-methylstyrene, o-methylstyrene, p-methoxystyrene, p-chlorostyrene and mixtures thereof. Examples of the derivatives of acrylic acid and methacrylic acid include, for example, methyl acrylate, ethyl acrylate, 2-hydroxyethyl acrylate, and 2-acrylic acid.
Examples thereof include hydroxypropyl, acrylamide, acrylonitrile, methacrylic acid derivatives corresponding to these, and mixtures thereof. This polyhydroxystyrene resin has a weight average molecular weight of 1,000 to 300.
When the weight average molecular weight is less than 1,000, the residual film ratio decreases and the resist pattern shape deteriorates. When it exceeds 30,000, the resolution deteriorates.

Further, as a resin which is made alkali-insoluble by protecting a part of hydroxyl groups with a substituent which is inactive to an acid,
For example, a resin in which a part of the hydroxyl group of the above-mentioned novolak resin or polyhydroxystyrene-based resin is protected with a substituent which is inactive to an acid can be used.

The term "acid-inactive substituent" means a substituent that is not changed by an acid. Examples of such a substituent include a substituted or unsubstituted benzenesulfonyl group and a substituted or unsubstituted benzenesulfonyl group. Examples include a naphthalene sulfonyl group, a substituted or unsubstituted benzenecarbonyl group, and a substituted or unsubstituted naphthalenecarbonyl group. Examples of the substituted or unsubstituted benzenesulfonyl group, benzenesulfonyl group, chlorobenzenesulfonyl group, methylbenzenesulfonyl group, ethylbenzenesulfonyl group, propylbenzenesulfonyl group, methoxybenzenesulfonyl group, ethoxybenzenesulfonyl group, propoxybenzenesulfonyl group, Examples of a substituted or unsubstituted naphthalenesulfonyl group include an acetaminobenzenesulfonyl group, and examples of a naphthalenesulfonyl group, a chloronaphthalenesulfonyl group, a methylnaphthalenesulfonyl group, an ethylnaphthalenesulfonyl group, a propylnaphthalenesulfonyl group, a methoxynaphthalenesulfonyl group Ethoxynaphthalenesulfonyl group, propoxynaphthalenesulfonyl group, and acetaminonaphthalenesulfonyl group. Examples of the substituted or unsubstituted benzenecarbonyl group and the substituted or unsubstituted naphthalenecarbonyl group include those in which the sulfonyl group in the above substituent is replaced with a carbonyl group.

The substitution rate of these acids with a substituent inert to the acid is 0.0 to the hydroxyl group of the alkali-soluble resin.
The range of 1 to 1 mol%, particularly the range of 0.08 to 0.15 mol% is preferred.

Among the phenolic hydroxyl group-containing alkali-soluble resins of the component (A), polyhydroxystyrene resins, particularly polyhydroxystyrene and copolymers of p-hydroxystyrene and styrene are preferred. Also,
As a resin that is made alkali-insoluble by protecting a part of the hydroxyl groups with an acid-inactive substituent, polyhydroxystyrene in which a part of the hydroxyl groups is replaced with an acetaminobenzenesulfonyl group has sensitivity and resolution. It is advantageous because it is excellent. These resin components may be used alone or in combination of two or more. The acid generator as the component (B) can be arbitrarily selected from compounds that generate an acid upon irradiation with actinic radiation, which are commonly used for chemically amplified resist compositions.

On the other hand, the crosslinkable compound of the component (C) can be arbitrarily selected from those conventionally used as a crosslinkable compound in a chemically amplified negative resist. Examples of such a crosslinkable compound include an amino resin having a hydroxyl group or an alkoxyl group, such as a melamine resin, a urea resin, a guanamine resin, a glycoluril-formaldehyde resin, a succinylamide-formaldehyde resin, and an ethylene urea-formaldehyde resin. Can be. These are, for example, melamine,
It is easily obtained from urea, guanamine, glycoluril, succinylamide, ethylene urea, etc. by reacting them with formalin in boiling water to form methylol or by further reacting a lower alcohol with them to alkoxylate, but commercially available products Nikarac Mx-7
50, Nikarac Mx-290, Nikarac Mx-30
(All manufactured by Sanwa Chemical Co., Ltd.) and the like.

Further, it has an alkoxyl group such as 1,3,5-tris (methoxymethoxy) benzene, 1,2,4-tris (isopropoxymethoxy) benzene, and 1,4-bis (sec-butoxymethoxy) benzene. A phenol compound having a hydroxyl group or an alkoxyl group such as a benzene compound, 2,6-dihydroxymethyl-p-cresol, and 2,6-dihydroxymethyl-p-tert-butylphenol can also be used. These crosslinkable compounds may be used alone, or 2
A combination of more than one species may be used.

Regarding the mixing ratio of each component in the negative resist layer, it is preferable that the resin of the component (A) and the crosslinkable compound of the component (C) are mixed in a weight ratio of 100: 3 to 100: 70. . If the amount of the crosslinkable compound is less than this range, the sensitivity may be insufficient.If the amount is more than this range, it is difficult to form a uniform resist layer, and the developability is also reduced, so that a good resist pattern is formed. It is difficult to obtain. From the viewpoints of sensitivity, formation of a uniform resist layer, and developability, a particularly preferable mixing ratio of the component (A) and the component (C) is 100: 5 to 100: 5 by weight.
It is selected in the range of 0.

The acid generator of the component (B) is used in an amount of 0.1 to the total weight of the components (A) and (C).
It is preferred to mix at a ratio of ３０30% by weight. If the amount of the component (B) is out of this range, an image is not easily formed, and
Developability also decreases, and it becomes difficult to obtain a good resist pattern. From the viewpoints of image forming properties and developability, this (B)
The particularly preferable compounding amount of the component is selected in the range of 1 to 20% by weight based on the total weight of the component (A) and the component (C).

In the method of the present invention, in order to laminate a photoresist film on a predetermined antireflection film, for example, the components (A), (B) and (C) are dissolved in a solvent, and a negative resist film is formed. It is preferable to prepare a solution for formation, apply the solution on the antireflection film using a conventional application means such as a spinner or a doctor knife, and dry the solution. As the solvent used for preparing the negative resist film forming solution, for example, ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, 1,1,1-trimethyl acetone, Ethylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate,
Or polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof, cyclic ethers such as dioxane, ethyl lactate, methyl acetate, ethyl acetate, acetic acid Esters such as butyl, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, and ethyl 3-ethoxypropionate can be exemplified. These may be used alone or as a mixture of two or more.

The solution for forming a negative resist film may further contain, if desired, a miscible additive such as an additional resin for improving the performance of the resist layer, a plasticizer, a stabilizer, a coloring agent, and an interface. A commonly used substance such as an activator can be added and contained.

In the method of the present invention, the thickness of the organic antireflection film formed on the substrate as described above is plotted on the horizontal axis, and the reflectance at the interface between the antireflection film and the photoresist film is determined. In the graph obtained by plotting as the vertical axis, the refractive index (n) of the antireflection film is set so that the allowable range of the film thickness that causes a variation value of 0.01 near the minimum point of the reflectance is within ± 0.01 μm. It is necessary to adjust the extinction coefficient (k).

The refractive index and the extinction coefficient of the antireflection film are adjusted, for example, by the components constituting the antireflection film, that is, the type of the high light-absorbing substance such as an ultraviolet absorber, a crosslinking agent or a binder resin, and the content ratio thereof. Can be done by changing For example, when an anthracene-based compound is used as the high light-absorbing substance, the extinction coefficient becomes larger than when a bisphenolsulfone-based compound is used,
When an acid component is added, the absorption coefficient and the refractive index tend to be higher than those not containing the acid component. On the other hand,
When the content ratio of the high light-absorbing substance is increased, the absorption coefficient tends to increase.For example, when an anthracene-based compound is used as the high light-absorbing substance, the refractive index increases when the content ratio is increased. In contrast, when a bisphenolsulfone compound is used, the refractive index tends to decrease when the content ratio is increased.

FIG. 2 shows that the refractive index (n) thus adjusted is 1.4, the extinction coefficient (k) is 0.3, 0.4,
The graph shows the relationship between the film thickness and the reflectance for the 0.5, 0.6 and 0.7 anti-reflection films, which show that the thickness is around 0.06 to 0.07 μm and 0.15 μm.
A local minimum point of the refractive index is observed in the vicinity. Next, FIG. 3 is a similar graph when the refractive index (n) is adjusted to 1.6, and FIG.
Is a similar graph when the refractive index (n) is adjusted to 1.8, FIG. 5 is a similar graph when the refractive index (n) is adjusted to 2.0, and FIG. 2 shows a similar graph when prepared at 0.2. In each of these graphs, the minimum point of the reflectance shifts toward the left side, that is, the smaller the film thickness, as the refractive index increases. In other words, the extinction coefficient (k) is 0.3 to 0.1.
In the range of 7, if the refractive index is adjusted to be large, the film thickness can be reduced within a certain allowable range. Therefore, according to the present invention, by selecting the composition of the antireflection film so as to increase the refractive index (n), it is possible to realize a thin antireflection film without any functional obstacle.

Specific examples of the composition for obtaining an antireflection film having a desired refractive index (n) and extinction coefficient (k) are shown below. (1) In the case of n = 1.6-1.65 and k = 0.5-0.6 Esterified product of polymethacrylic acid and 4,4′-dihydroxyphenylsulfone (0.83 g) / anthracene methanol (0 .83 g) / benzoguanamine (Cymer 1125) (0.83 g) / propylene glycol monomethyl ether (97.5 g) (2) When n = 1.8 and k = 0.4 4,4′-dihydroxyphenyl sulfone (2 .5g)
/ Benzoguanamine (Cymel 1125) (2.5 g)
/ Propylene glycol monomethyl ether (95.0
g) (3) When n = 1.45 and k = 0.4 Benzoguanamine (Cymel 1125) (1.0 g) /
Anthracenecarboxylic acid (1.0 g) / glycidyl methacrylic acid-methyl methacrylic acid copolymer (1.0 g)
/ Propylene glycol monomethyl ether (97.0
g).

Next, in order to form a pattern using the thus obtained resist laminate having a thinned antireflection film, a conventional lithography technique is first used to form a pattern on the negative resist layer, for example. Using a reduction projection exposure device,
After selectively irradiating an actinic ray such as deep-UV or excimer laser light through a mask pattern, a heat treatment is performed, and then this is subjected to a developing solution, for example, a 1 to 10% by weight aqueous solution of tetramethylammonium hydroxide. After developing with an alkaline aqueous solution to form a negative resist pattern on the antireflection layer, the exposed antireflection layer is etched using the negative resist pattern as a mask using a dry etching apparatus using plasma or the like. I do. Thus, a fine image faithful to the mask pattern can be obtained.

[0040]

Next, the present invention will be described in more detail by way of examples.

Example 1 Esterified product of polymethacrylic acid and 4,4'-dihydroxyphenylsulfone (0.83 g), anthracenemethanol (0.83 g), benzoguanamine (Cymel 1125) (0.83 g) and propylene glycol monomethyl A composition for forming an antireflection film comprising ether (97.5 g) was prepared. This was spin-coated on a substrate and heated at 180 ° C. for 90 seconds to form an anti-reflection film having a thickness of 0.05 μm. TDUR-DP018 [manufactured by Tokyo Ohka Kogyo Co., Ltd.], which is a chemically amplified positive photoresist, was formed on the antireflection film layer. In this case, the n value is 1.63, the k value is 0.55, and the point where the allowable range of the film thickness that causes a variation near the minimum point of the reflectance falls within ± 0.01 μm is 0.05 μm. There was a match with the actual film thickness. After exposing using a reduction projection exposure apparatus Nikon NSR-2005EX8A (manufactured by Nikon) through a mask pattern, a heat treatment is performed on a hot plate at 130 ° C. for 90 seconds, and then 2.38 wt% tetramethylammonium hydroxy The photoresist pattern was obtained by developing with an aqueous solution and washing with pure water. Observation of the obtained resist pattern by SEM (scanning electron microscope) revealed that a rectangular photoresist pattern having a pattern side wall of 0.18 μm was obtained. Further, no distortion due to the standing wave was observed on the pattern side wall.

Example 2 4,4'-dihydroxyphenylsulfone (2.5
g), benzoguanamine (Cymel 1125) (2.5
g) and propylene glycol monomethyl ether (9
5.0 g) was prepared. This is spin-coated on a substrate,
Heating was performed for 2 seconds to form an antireflection film having a thickness of 0.045 μm. TDUR-DP018 [Tokyo Ohka Kogyo Co., Ltd.] which is a chemically amplified positive photoresist on the antireflection film.
Was formed. In this case, the n value is 1.8 and the k value is 0.40
The minimum point within the allowable range ± 0.01 μm is 0.0
It was 45 μm. Reduction projection exposure apparatus Nikon NSR-2005EX8A (manufactured by Nikon Corporation) through a mask pattern
After exposure using, a heat treatment is carried out on a hot plate at 130 ° C. for 90 seconds, followed by a development treatment with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide and washing with pure water to form a photoresist pattern. Obtained. Observation of the obtained resist pattern by SEM (scanning electron microscope) revealed that the pattern side wall was 0.18 μm.
m rectangular photoresist pattern was obtained. Further, no distortion due to the standing wave was observed on the pattern side wall.

Example 3 Benzoguanamine (Cymel 1125) (1.0 g),
Anthracene carboxylic acid (1.0 g), glycidyl methacrylic acid-methyl methacrylic acid copolymer (1.0 g)
And propylene glycol monomethyl ether (97.
0g) was prepared. This was spin-coated on a substrate and heated at 180 ° C. for 90 seconds to form an antireflection film having a thickness of 0.07 μm. T which is a chemically amplified positive photoresist on the antireflection film
DUR-DP018 [manufactured by Tokyo Ohka Kogyo Co., Ltd.] was formed. In this case, the n value is 1.45, the k value is 0.40, and the minimum point within the allowable range ± 0.01 μm is 0.07 μm.
m. After exposing using a reduction projection exposure apparatus Nikon NSR-2005EX8A (manufactured by Nikon) through a mask pattern, a heat treatment is performed on a hot plate at 130 ° C. for 90 seconds, and then 2.38 wt% tetramethylammonium hydroxy The photoresist pattern was obtained by developing with an aqueous solution and washing with pure water. The obtained resist pattern is subjected to SEM (scanning electron microscope)
As a result, a rectangular photoresist pattern having a pattern side wall of 0.18 μm was obtained. Further, no distortion due to the standing wave was observed on the pattern side wall.

Example 4 Melamine (Mx-750) (1.0 g) and anthracenecarboxylic acid (0.5 g) were dissolved in 67 g of propylene glycol monomethyl ether to prepare a composition for forming an antireflection film. This is spin-coated on a substrate and
Heating was performed at 80 ° C. for 90 seconds to form an antireflection film having a thickness of 0.045 μm. TDUR-P308 [manufactured by Tokyo Ohka Kogyo Co., Ltd.], which is a chemically amplified positive photoresist, was formed on the antireflection film. The n value in this case is 1.80,
The k value is 0.60, and the point where the allowable range of the film thickness that causes the fluctuation value near the minimum point of the reflectance falls within ± 0.01 μm is 0.045 μm, which coincides with the actual film thickness. Was.
Next, this was treated in the same manner as in Example 1 to obtain a photoresist pattern. When this was observed by SEM (scanning electron microscope), a rectangular photoresist pattern having a pattern side wall of 0.15 μm was obtained, and no distortion due to a standing wave was observed on the pattern side wall.

Example 5 Polyglycidyl methacrylate (1.0 g) having a weight average molecular weight of 10,000 and 9-anthracene carboxylic acid (0.5 g) were dissolved in 60 g of propylene glycol monomethyl ether to form an antireflection film. A composition was prepared. This is applied on the substrate with a spinner,
Heating was performed at 180 ° C. for 90 seconds to form an antireflection film having a thickness of 0.06 μm. TDUR-P308 [manufactured by Tokyo Ohka Kogyo Co., Ltd.], which is a chemically amplified positive photoresist, was formed on the antireflection film. The n value in this case is 1.40,
The k value is 0.40, and the point at which the allowable range of the film thickness that causes a variation near the minimum point of the reflectance falls within ± 0.01 μm is 0.060 μm, which is consistent with the actual film thickness. Was.
Next, this was treated in the same manner as in Example 1 to form a photoresist pattern.
Of the photoresist pattern was obtained, and no distortion due to the standing wave on the pattern side wall was observed.

Comparative Example 4,4'-dihydroxyphenylsulfone (1.75
g), benzoguanamine (Cymel 1125) (1.7)
5 g) and propylene glycol monoethyl ether (96.5 g) were prepared. This is spin-coated on a substrate,
Heating was performed for 0 second to form an antireflection film layer having a thickness of 0.05 μm. TDUR-DP018 [Tokyo Ohka Kogyo Co., Ltd.] which is a chemically amplified positive photoresist on the antireflection film layer.
And exposure using a reduction projection exposure apparatus Nikon NSR-2005EX8A (manufactured by Nikon Corporation) through a mask pattern, and 90 ° C. at 130 ° C. on a hot plate.
A heat treatment was performed for 2 seconds, followed by development with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide and washing with pure water to obtain a photoresist pattern. Observation of the obtained photoresist pattern by SEM (scanning electron microscope) revealed that the pattern side wall was distorted by a standing wave on the pattern side wall, and a rectangular photoresist pattern was not obtained. When the n value and k value of this antireflection film material were measured, n = 1.80 and k =
0.40, and the minimum point within the allowable range of ± 0.01 μm was 0.11.

[Brief description of the drawings]

FIG. 1 is a model diagram for explaining a configuration of a method of the present invention.

FIG. 2 is a graph showing the relationship between the film thickness and the reflectance when n = 1.4.

FIG. 3 is a graph showing the relationship between the film thickness and the reflectance when n = 1.6.

FIG. 4 is a graph showing the relationship between the film thickness and the reflectance when n = 1.8.

FIG. 5 is a graph showing the relationship between film thickness and reflectance when n = 2.0.

FIG. 6 is a graph showing the relationship between the film thickness and the reflectance when n = 2.2.

Claims (5)

[Claims] 1. A method for forming a fine pattern by subjecting a photoresist film laminated on a substrate via an organic anti-reflection film to image formation exposure and then performing a development treatment to form a fine pattern. In a graph in which the thickness is plotted on the horizontal axis and the reflectance at the interface between the organic antireflection film and the photoresist film is plotted on the vertical axis, the allowable value of the film thickness that causes a variation value of 0.01 near the minimum point of the reflectance is shown. A method for forming a fine pattern, wherein the refractive index and the extinction coefficient of the organic antireflection film are adjusted so that the range is within ± 0.01 μm. 2. The method according to claim 1, wherein the reflectance at the minimum point is 0.01 or less. 3. The method for forming a fine pattern according to claim 1, wherein the adjustment of the refractive index and the extinction coefficient of the organic antireflection film is performed by selecting the type and content of the resin component therein. 4. The method for forming a fine pattern according to claim 1, wherein the adjustment of the refractive index and the extinction coefficient of the organic antireflection film is carried out by selecting the kind and the content ratio of the highly light-absorbing substance therein. 5. The method for forming a fine pattern according to claim 1, wherein the refractive index and the extinction coefficient of the organic antireflection film are adjusted by selecting the type and content of the thermally crosslinkable compound therein.