JPH08305022A - Coating composition for improving performance of lithography and pattern forming method using the coating composition - Google Patents

Abstract

PURPOSE: To provide a coating compsn. for improving performances of lithography and to provide a pattern forming method using the coating compsn. CONSTITUTION: This coating compsn. is an alkali compsn. to be applied on the upper surface of a quinonediazide photoresist compsn. coating film. The coating compsn. is applied on the upper surface of a quinonediazide photoresist compsn. coating film formed on a substrate, irradiated with light to transfer a latent image of a pattern, then heat-treated and developed. Thereby, only by coating one kind of surface coating compsn., a good pattern can easily be formed having resolution, good shape and focal depth of the transferred pattern and little changes in the dimension of the transferred pattern without depending on the coating film thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for improving performance in lithography and a pattern forming method using the coating composition.

[0002]

2. Description of the Related Art In recent years, the fine processing technology (photolithography technology) used for manufacturing integrated circuits has been remarkably improved in processing accuracy. For example, in a dynamic random access memory (DRAM), submicron processing is possible. Has been established as a mass production level technology. For submicron processing, as an exposure light source,
Light having a short wavelength such as g-line (436 nm), i-line (365 nm), and KrF excimer laser light (248 nm) is used, and the photoresist composition used is
Various high performance photoresist coating compositions have been proposed.

The properties required for the above photoresist coating composition (pattern forming method) are not only higher resolution, but also the transfer pattern shape is more rectangular and favorable, and There is a demand for a high-performance photoresist coating composition (pattern forming method) having characteristics such as a large depth of focus. To achieve such purpose,
In advance, a method of transferring a pattern after subjecting the photoresist coating composition to an alkali treatment, or a method of applying a photobleaching material on the photoresist composition coating film to improve the effective contrast of projected light is proposed. (Semicon NEWS, 8 , vol 12, 60)
(1988)).

In order to further reduce the dimensional variation of the transferred pattern due to the coating film thickness, a transparent film having a refractive index different from that of the photoresist composition coating film is formed on the photoresist composition coating film to apply the photoresist composition. Using the interference of the phase difference between the light reflected from the upper surface of the film and the light that has passed through the upper surface of the photoresist composition coating film and is reflected by the newly coated film having a different refractive index, the above-mentioned film A method of reducing the influence of internal multiple reflection to improve dimensional controllability has been proposed (JP-A-60-149130, JP-A-62-62520, JP-A-62-62521, JP-A-62-62521, Kaihei 5-188598, etc.).

However, in the case of the method of subjecting the coating film to alkali treatment, the entire surface of the coating film is subjected to alkali treatment, so that even an exposed portion which originally does not require alkali treatment is subjected to alkali treatment, and as a result, development of scum or the like occurs. There is a problem that the residue will occur. Further, in the case of a method using a coating film having a low refractive index, only an acidic composition is known as a composition that achieves a low refractive index (1.45 or less) that is significant in the process. Therefore, the present situation is that no method has been proposed that can reduce the dimensional variation of the pattern and at the same time improve the pattern shape.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to achieve a high resolution by a simple method of applying only one type of surface coating composition. The shape and depth of focus of the transfer pattern is good,
Moreover, it is an object of the present invention to provide a pattern forming method in which a change in transfer pattern dimension due to a coating film thickness is small and a good result is obtained.

[0007]

That is, the first aspect of the present invention
The gist of is a coating composition used by coating on the upper surface of a quinonediazide-based photoresist composition coating film, which is a coating composition for improving performance in lithography characterized by being alkaline, The gist of item 2 is that the above coating composition is applied on the upper surface of the quinonediazide photoresist composition coating film applied on the substrate, light is projected to transfer the pattern latent image, and then heat treatment is performed, followed by development. The present invention resides in a pattern forming method characterized by performing

The present invention will be described in detail below. The present invention can be applied to both the conventionally known negative type and positive type comprising a quinonediazide type photoresist coating composition, but is particularly suitable for a positive type photoresist coating composition. A quinonediazide-based positive photoresist coating composition generally contains an alkali-soluble resin, a quinonediazide compound, and a solvent. Examples of the alkali-soluble resin include novolac resin, polyhydroxystyrene or its derivative, styrene-maleic anhydride copolymer, and the like, and novolak resin, polyhydroxystyrene or its derivative are preferable. Novolak resin is
It can be obtained by heating polycondensation of a hydroxy aromatic compound and a carbonyl compound in the presence of an acidic catalyst.

As the above-mentioned hydroxy aromatic compound,
For example, phenol, o-cresol, m-cresol, p-cresol, 3-ethylphenol, 2,5-
Phenols which may be substituted with an alkyl group or an aryl group such as xylenol, 3,5-xylenol and phenylphenol; alkoxy or allyloxyphenols such as 2-methoxyphenol, 4-methoxyphenol and 4-phenoxyphenol; Naphthols which may be substituted with an alkyl group such as α-naphthol, β-naphthol and 3-methyl-α-naphthol;
3-dihydroxybenzene, 1,3-dihydroxy-2
-Methylbenzene, 1,2,3-trihydroxybenzene, 1,3,5-trihydroxybenzene, 1,2,3
Examples thereof include polyhydroxybenzenes which may be substituted with an alkyl group such as trihydroxy-5-methylbenzene.

Examples of the carbonyl compound include aliphatic aldehydes such as formaldehyde, paraformaldehyde and acetaldehyde; aromatic aldehydes such as benzaldehyde and hydroxybenzaldehyde; and alkyl ketones such as acetone. Examples of the above-mentioned acidic catalyst include hydrochloric acid, sulfuric acid, oxalic acid and the like.

Examples of polyhydroxystyrene include polymers such as 4-hydroxystyrene, 3-methyl-4-hydroxystyrene and 3-chloro-4-hydroxystyrene. Examples of the polyhydroxystyrene derivative include copolymers of the above polyhydroxystyrene and other components, and as the other components, styrene,
Styrene derivatives such as 4-methylstyrene and stilbene;
Ethylene derivatives such as ethylene and propylene; maleic acid derivatives such as maleic acid, 2-methylmaleic acid, N- (4-hydroxyphenyl) maleimide; acrylic acid,
Examples thereof include acrylic acid derivatives such as methacrylic acid, ethyl acrylate, and ethyl methacrylate.

The above novolak resin, polyhydroxystyrene or its derivative may be reduced with hydrogen or the like, if necessary, in order to lower the absorption in the short wavelength region, and as long as it does not adversely affect the present invention. Alternatively, the aromatic ring may have a substituent such as a halogen atom, a nitro group, or an ester group. In addition, part of the phenolic hydroxyl group is t
-Esterified products such as butyloxycarbonate and acetate; may be substituted as etherified products such as methyl ether, trimethylsilyl ether, and tetrahydropyranyl ether.

The optimum weight average molecular weight of the alkali-soluble resin is usually 2,000 to 30,000, preferably 3,000.
~ 20,000. It is also possible to use a resin from which the low molecular weight components have been removed from the above resin by fractional precipitation or the like, or a resin having a broad molecular weight distribution by mixing two or more kinds of resins having different molecular weights.

The quinonediazide compound is usually
1,2-benzoquinonediazide-4-sulfonic acid,
1,2-naphthoquinonediazide-4-sulfonic acid,
Examples thereof include orthoquinonediazide compounds such as esters or amides such as 1,2-naphthoquinonediazide-5-sulfonic acid, and specifically, polyhydroxyalkyl compounds such as glycerin and pentaerythritol, novolac resins, bisphenol A, 4,4. ′, 4 ″ -trihydroxyphenylmethane, gallic acid ester, quercetin,
Polyhydroxy aromatic compounds such as morin and polyhydroxybenzophenone, and 1,2-benzoquinonediazide-4
-Sulfonic acid, 1,2-naphthoquinonediazide-4-
Esters such as sulfonic acid and 1,2-naphthoquinonediazide-5-flufonic acid may be mentioned. Among these, esters of phenol compounds are particularly preferable. Also,
Photosensitizers containing usually two or more, preferably three or more orthoquinonediazide groups in one molecule are preferred.

As the solvent, ethyl acetate, butyl acetate,
Carboxylic acid esters such as γ-butyrolactone; ethylene glycol methyl ether, ethylene glycol ethyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether and other glycol ethers; ethylene glycol ethyl ether acetate, propylene Glycol ether alkyl carboxylic acid esters such as glycol methyl ether acetate and propylene glycol methyl ether propionate; hydroxyalkyl carboxylic acid esters such as methyl lactate and ethyl lactate; methyl 3-methoxypropionate, methyl 3-ethoxypropionate, Ethyl 3-ethoxypropionate, 2-methyl-
Alkoxyalkylcarboxylic acid esters such as methyl 3-methoxypropionate and ethyl 2-methyl-3-ethoxypropionate; pyruvate esters such as methyl pyruvate and ethyl pyruvate; ketones such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone Examples thereof include a single solvent or a mixed solvent of two or more kinds.

In the quinonediazide positive type photoresist coating composition, the concentration of the alkali-soluble resin is usually 1 to 30% by weight, and the concentration of the quinonediazide compound is usually 0.01 to 15% by weight. The ratio of the quinonediazide compound to the alkali-soluble resin is usually 0.001 to 1.0 times by weight. The quinonediazide-based positive photoresist coating composition includes a coatability improving agent for improving coatability, a light-absorbing material for reducing the influence of irregularly reflected light from the substrate, and a sensitizer for improving sensitivity. Additives can be added.

The coating composition for improving performance in lithography of the present invention is used by coating it on the upper surface of a coating film of the above quinonediazide photoresist composition. Then, if it is alkaline, it may be dissolved in either an organic solvent or an aqueous medium, but there is no mixing with the quinonediazide-based photoresist composition coating film coated in the lower layer, and the photolithography is performed with an aqueous developer. The water-soluble coating composition is preferable from the viewpoint that it is a preferred embodiment that development, dissolution, and removal are performed simultaneously with the resist coating film.

As the aqueous medium, water that may contain an organic solvent that may be mixed with water, such as methanol, ethanol, and isopropanol, which may be substituted with a fluorine atom, is used. However, from the viewpoint of preventing mixing,
The amount of the organic solvent to be mixed is preferably as small as possible, and the amount of the organic solvent is usually 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less as a ratio to the total medium.

The coating composition of the present invention usually contains a film forming material. As such a film-forming material, water-soluble ones are preferably used from the same viewpoints as described above, and specific film-forming materials include polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, and polyvinylmethyl. Water-soluble polymers such as ether and pullulan are mentioned. A part or all of these film forming materials may be replaced with a water-soluble fluorine compound described later. The amount of the film-forming material used is usually 0.1 to the total coating composition.
It is 20% by weight, preferably 1 to 10% by weight. Since many of these film forming materials have a refractive index of 1.5 or more, it is preferable that the amount used is small. The method of substituting a part of the film forming material with a fluorine compound is a preferred embodiment for lowering the refractive index described later.

The alkalinity of the coating composition of the present invention is usually 7.1 to 14, preferably 8 to 13, and more preferably 8.5 to 1 in terms of pH of the coating composition liquid.
It is 2.5. The alkalinity can be adjusted with an organic amine such as an aqueous solution of tetramethylammonium hydroxide.

It is essential that the coating composition of the present invention is alkaline as described above. The reason why good results can be obtained by making it alkaline is that the quinonediazide compound undergoes a coupling reaction with an alkali-soluble resin of a phenolic compound under alkaline conditions, resulting in a reduced solubility in a developing solution. The progress of the above coupling reaction depends on conditions such as the strength of alkalinity and the ambient temperature.

Therefore, since the optimum alkalinity varies depending on the conditions of the photolithography process, such as the baking process, it is necessary to comprehensively consider them. For example, if the alkaline conditions are too strong, the dissolution rate of the exposed part in the developing solution cannot be increased sufficiently after the exposure, and undeveloped residue such as scum occurs, and if the alkaline conditions are too weak, the It is difficult to achieve the object of the invention.

Even better results are obtained if a photosensitive acid-generating compound is added to the coating composition of the present invention. That is, as described above, in the alkali treatment, the undeveloped portion such as scum may occur in the exposed portion, but this is because the exposed portion, which is originally not preferable in the prior art, is alkali-treated. This is because the suitable range of condition setting is narrow. On the other hand, if a photosensitive acid generating compound is added to the coating composition of the present invention, the exposed portion of the coating composition can be changed to acid after exposure, and as a result, the alkali treatment of the exposed portion can be performed. It is mitigated and the residual development such as scum is improved.

As the photosensitive acid generating compound, a compound containing a polyhalogenated hydrocarbon group, an onium salt compound,
Examples thereof include sulfonic acid ester compounds and sulfone compounds. Among them, water-soluble compounds having a water-soluble group in the molecule are preferably used.

Specific examples of the water-soluble photosensitive acid generating compound include diphenyliodonium hexafluorophosphonate, diphenyliodonium trifluoromethanesulfonate, triphenylsulfonium bromide,
Triphenylsulfonium hexafluorophosphonate, triphenylsulfonium trifluoromethanesulfonate, diphenyl- (4-methoxyphenyl)
Sulfonium trifluoromethanesulfonate, tris (4-methoxyphenyl) sulfonium trifluoromethanesulfonate, diphenyl- (4- (phenylthio) phenyl) sulfonium trifluoromethanesulfonate, diphenyl- (4- ( Phenylthio) phenyl) sulfonium hexafluorophosphonate, dimethyl- (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, 2-naphthoylmethyltetramethylenesulfonium trifluoromethanesulfonate and other onium salts; benzenesulfone Examples thereof include acid amides, p-toluenesulfonic acid amides, sulfonic acid amides such as benzenesulfonic acid hydrazide, and the like.

The mixing ratio of the photosensitive acid generating compound is as a mixing ratio with respect to the total amount of the components excluding the solvent of the coating composition.
Usually 0.005 to 0.2 times by weight, preferably 0.01 to
It is 0.1 times the weight. The amount of the photosensitive acid generating compound added is determined in consideration of the pH of the coating composition liquid, and is adjusted so that the exposed portion can be acidified after exposure.

Further, in the coating composition of the present invention, the refractive index of the coating film with respect to the projected light wavelength is [m ^0.5 ] when the refractive index of the lower layer photoresist composition coating film is represented by [m].
If the composition of the coating composition of the present invention is set to an odd multiple of λ / 4, and the projection light wavelength is set to λ, the effect of the multiple reflection in the film is reduced. This is preferable because it can be performed.

The preferred refractive index of the coating film formed from the coating composition of the present invention is 1.25 to 1.1 because the refractive index of a conventional photoresist composition coating film is usually 1.6 to 1.7.
It is set to 3. However, in practice, it is very difficult to obtain such a coating film having a low refractive index, and therefore, a practically suitable range is 1.3 to 1.45. According to the coating film having such a refractive index, the reflected light intensity is reduced due to the interference effect, and the dimensional controllability of the coating film thickness of the photoresist composition coating film is improved.

A fluorine-containing compound is effective as a material for achieving the above low refractive index coating film, and it is preferable to add a water-soluble fluorine-containing compound to the coating composition of the present invention. As a preferable water-soluble fluorine-containing compound, a water-soluble fluorine compound described in Japanese Patent Application No. 7-64132 already filed by the present applicant, that is, 1
Examples include the below-mentioned water-soluble fluorine compound which is solid at 20 ° C. and / or the below-mentioned water-soluble fluorine compound which is liquid at 20 ° C. and has a boiling point of 100 ° C. or higher at 1 atm. In particular, the use of these mixtures makes it possible to reduce the amount of the film-forming material such as polyacrylic acid used and to obtain the coating film having a low refractive index of 1.45 or less. The amount of the fluorine-containing compound used is usually 0.1 to 20% by weight, and preferably 1 to 10% by weight, based on the entire coating composition, like the film forming material.

The above-mentioned water-soluble fluorine compound which is solid at 1 atmosphere and 20 ° C. is preferably a water-soluble fluorine compound which is solid at 1 atmosphere and 25 ° C., and more preferably has a boiling point of 150 ° C. or more at 1 atmosphere. Preferably 2
A compound having a temperature of 00 ° C or higher, most preferably 250 ° C or higher. The term "water-soluble" as used herein means that it is usually dissolved in 0.1% by weight or more, preferably 1% by weight or more in the above aqueous medium under the condition of 1 atm and 20 ° C.

Examples of the above water-soluble fluorine compound include perfluoroalkylsulfonic acid and perfluoroalkylcarboxylic acid having a carbon number of usually 3 to 30, preferably 5 to 20. As another example, carbon number is usually 8
To 40, preferably 9 to 20, perfluoroalkylbenzenesulfonic acid, perfluoroalkyloxybenzenesulfonic acid, perfluoroalkylbenzenecarboxylic acid, and perfluoroalkyloxybenzenecarboxylic acid. Still other examples include perfluoroalkyl polyether sulfonic acids and perfluoroalkyl polyether carboxylic acids having usually 4 to 1000 carbon atoms, preferably 4 to 500 carbon atoms. These fluorine-containing acid compounds are used as free acids,
Ammonium salt, mono optionally substituted with fluorine
It is used in the form of a tetraalkylammonium salt or the like, and may be used as a mixture of two or more kinds.

Specific examples of the above-mentioned fluorine-containing acid compound include perfluorobutane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorodecane sulfonic acid, perfluorobutanoic acid, perfluoroadipic acid, and perfluoroadipic acid. Fluorooctanoic acid, perfluoroazelic acid, perfluorosebacic acid, perfluoro-1,10-decanedicarboxylic acid, perfluoroheptaoxybenzenesulfonic acid,
Perfluoro (2-ethoxyethane) sulfonic acid, perfluoroalkyl polyether sulfonic acid (for example, a product "Nafio" manufactured by EI duPont).
n ”), perfluoro-2,5-dimethyl-3,6-dioxanonanoic acid, perfluoro-2,5,8-trimethyl-3,6,9-trioxadodecanoic acid, perfluoroalkyl polyether dicarboxylic acid, etc. Is mentioned.
Further, specific examples of other solid water-soluble fluorine compounds include 2,2,3,3,4,4-hexafluoropentane-1,5-diol, 2,2,3,3,4,4,4. 5,5
Examples include fluoroalkyl alcohols such as -octafluorohexane-1,6-diol, and fluorinated surfactants manufactured by Mitsubishi Materials Corporation, such as "EF-121" (trade name).

On the other hand, the water-soluble fluorine compound which is liquid at 1 atm 20 ° C. and has a boiling point of 100 ° C. or more at 1 atm is preferably liquid at 1 atm 10 ° C. and boiling at 1 atm. Is 100 ° C. or higher, more preferably 150 ° C. or higher, and more preferably 200 ° C. or higher. Here, the term "water-soluble" means that it is usually 0.1 in the above aqueous medium under the condition of 1 atm and 20 ° C.
It means to dissolve by weight% or more, preferably 1% by weight or more.

As the above-mentioned water-soluble fluorine compound, for example, acidic compounds such as trifluoromethanesulfonic acid and heptafluorobutanoic acid can be used. However, since these acidic compounds suppress corrosion of equipment and the like, a large amount thereof is used. It is preferred to avoid using From this point of view, the water-soluble fluorine compound is preferably a neutral compound. Examples of the neutral water-soluble fluorine compound include compounds represented by the following chemical formula.

[0035]

Embedded image R ₁ — (R ₂ —O) _m — (CX ₂ ) _n —CX (OH) —CX ₂ (OH)

In the above chemical formula, R ₁ represents a fluorine-containing alkyl group, R ₂ represents a fluorine-containing alkylene group, X represents a hydrogen atom or a fluorine atom, and these may be the same or different. . m and n represent the integer of 0-5.

Specific examples of the neutral water-soluble fluorine compound represented by the above chemical formula include 3- (2-perfluorohexyl) ethoxy-1,2-dihydroxypropane and the like, which are similar compounds. Perfluoroalkyl alcohol ethylene oxide adducts such as α-perfluorononenyl-ω-methoxypolyoxyethylene and its terminal alkyl ether compounds cause peeling of the transferred pattern after exposure / development, which is not preferable. .

Other neutral water-soluble fluorine compounds include
2,2,3,3-tetrafluoropropanol, 2,
2,3,3,4,4-hexafluorobutanol, 2,
Fluoroalkyl alcohols such as 2,3,3,4,4,5,5-octafluoropentanol, and fluorochemical surfactants manufactured by Sumitomo 3M Limited, for example, the product "FC
-171 "(perfluoroalkylalkoxylate)," FC-430 "(fluorinated alkyl ester)
Etc.

The above fluorine compounds may be used alone or in combination with 2
It is used as a mixture of one or more kinds, and particularly, the use as a mixture of a compound having a boiling point of 1 atm of 100 ° C or more and 200 ° C or less and a compound having a boiling point of 200 ° C or more gives preferable results.

The above-mentioned solid or liquid water-soluble fluorine compound is a compound in which a hydrogen atom of an alkyl group is substituted with a fluorine atom, and the fluorine substitution ratio is preferably higher, usually 50%, preferably 70%. % Or more.

The water-soluble fluorine compound is used by adding it to the above film-forming material. And although the addition may be one kind, for example, the solid fluorine compound and the liquid fluorine compound are in a weight ratio of usually 10: 1 to 1:20, preferably 5: 1 to 1:10. By mixing and using them, a coating film having a low refractive index can be favorably formed without using a film forming material.

If the coating composition of the present invention contains a compound whose absorbance of the coating film with respect to the wavelength of the projection light is reduced by the projection of the projection light, the exposed portion and the unexposed portion in the photoresist coating film are included. This is preferable because the contrast of light with and is improved and high resolution is obtained. The decrease rate of absorbance is usually 10% or more as the decrease rate before and after complete change,
It is preferably 30% or more, more preferably 50% or more.

As the above-mentioned compound for reducing absorbance, α-
Carboxy-N-methyl nitrone, α- (p- (dimethylamino) phenyl) -N- (4-carboxyphenyl) nitrone, α- (p- (diethylamino) phenyl) -N- (4-carboxyphenyl) nitrone, α-
(P- (dimethylamino) phenyl) -N- (2-methyl-4-carboxyphenyl) nitrone, α- (p-
(Diethylamino) phenyl) -N- (2-methyl-4)
-Carboxyphenyl) nitrone, α- (p- (dimethylamino) styryl) -N- (4-carboxyphenyl) nitrone, α- (p- (diethylamino) styryl) -N- (4-carboxyphenyl) nitrone, α −
(P- (dimethylamino) styryl) -N- (2-methyl-4-carboxyphenyl) nitrone, α- (p-
(Diethylamino) styryl) -N- (2-methyl-4)
-Carboxyphenyl) nitrone and the like.

The mixing ratio of the compound for reducing absorbance is usually 0.01 to 0.5 times by weight, preferably 0.1 to 0.4 times by weight, based on the total amount of the components excluding the solvent of the coating composition. .

As a pattern forming method using a coating film of the coating composition of the present invention, basically, a conventional quinonediazide-based positive photoresist in which a coating film such as a protective film is formed on the upper surface of the photoresist coating film is used. A method similar to the case can be adopted. Specifically, the following procedure can be adopted.

First, a quinonediazide-based positive photoresist composition is applied to a substrate and then prebaked (1) to evaporate the remaining solvent. Then, the coating composition of the present invention is applied onto the coating film of the quinonediazide-based positive photoresist composition and then prebaked (2) to evaporate the remaining solvent. It is also possible to omit the pre-bake (1) and simultaneously evaporate the solvent of the coating film in each step in the pre-bake (2).
Can be omitted.

Next, exposure is performed to form a pattern latent image. Exposure can be performed by g-line, i-line, excimer laser light, etc., and the coating composition of the present invention can correspond to all these exposure wavelengths. Of course, the material and the like are optimized with respect to the exposure wavelength. Then, after exposure, baking is performed, and then development is performed to form a pattern. As a developing solution, an organic amine aqueous solution is usually used, and tetramethylammonium hydroxide and /
Alternatively, an aqueous solution of choline is preferably used. Further, prior to contact with the developing solution, the coating film of the coating composition of the present invention may be dissolved and removed with water, and then the quinonediazide positive photoresist coating film may be contacted with the developing solution.

[0048]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist.

(Preparation example A of surface coating composition) Salt obtained by neutralizing heptadecafluorooctane sulfonic acid with tetramethylammonium hydroxide (neutralization ratio 100%).
6 g, 2.4 g of 3- (2-tridecafluorohexyl) ethoxy-1,2-dihydroxypropane and 0.6 g of 2-naphthoylmethyltetramethylene sulfonium trifluoromethane sulfonate were dissolved in 96 g of water. Furthermore, the pH of the composition solution was adjusted to 10 with tetramethylammonium hydroxide. 0.2 of this solution
A surface coating composition A was prepared by filtering with a μm filter.

(Preparation Example B for Surface Coating Composition) Preparation Example A for surface coating composition except that the 2-naphthoylmethyltetramethylene sulfonium trifluoromethanesulfonate was not used in Preparation Example A for surface coating composition. Surface coating composition B was prepared in the same manner.

(Preparation Example C for Surface Coating Composition) In Preparation Example A for surface coating composition, the neutralization ratio with tetramethylammonium hydroxide was changed to 95%, and the pH of the composition solution was changed.
A surface coating composition C was prepared in the same manner as in the surface coating composition preparation example A except that the value was changed to 3.5.

(Preparation Example D of surface coating composition) Salt obtained by neutralizing heptadecafluorooctane sulfonic acid with tetramethylammonium hydroxide (neutralization ratio 100%).
0 g, 3- (2-tridecafluorohexyl) ethoxy-1,2-dihydroxypropane 4.0 g, 2-naphthoylmethyltetramethylenesulfonium trifluoromethanesulfonate 0.7 g, α- [p- (dimethyl Amino) phenyl] -N- (4-carboxyphenyl)
2.0 g of nitrone was added to 91 g of water, and the pH of the composition solution was adjusted to 1 with tetramethylammonium hydroxide.
It was adjusted to 0 and dissolved. This solution was filtered with a 0.2 μm filter to prepare a surface coating composition D.

Examples 1-2 and Comparative Examples 1-2 quinonediazide positive photoresist (trade name: MCPRi6600) manufactured by Mitsubishi Chemical Co., Ltd. was spin-coated on four 5-inch silicon wafers, respectively, and further,
Surface coating composition A to three silicon wafers among them
C is applied to each, and the mixture is placed on a hot plate at 70 ° C for 6
The coated film was dried by heating and baking for 0 seconds (Examples 1 and 2).
And Comparative Example 1). The coating thickness of photoresist is about 1μ
m, the coating thickness of the surface coating composition was about 670Å.

Next, it was exposed with an i-line stepper manufactured by Nikon (trade name: NSR1755i7A), exposed on a hot plate at 120 ° C. for 90 seconds and then baked, and further,
After rinsing and removing the surface coating composition with water, paddle development was performed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide aqueous solution. The pattern shape and the like were observed with an exposure amount that gives an L & S (ratio of line width to space width) of 0.5 μm of 1: 1. One of the four silicon wafers was exposed and developed without applying the surface coating composition (Comparative Example 2).

As a result, in the case of Example 1 in which the surface coating composition A was used for exposure and development, the resolution was good with rectangularity up to 0.34 μm and there was no scum. In the case of Example 2 in which the surface coating composition B was used for exposure and development, the rectangularity of the pattern was well resolved up to 0.35 μm, but some scum was generated.
On the other hand, in the case of Comparative Example 1 in which the surface coating composition C was used for exposure and development, the resolution was only up to 0.36 μm, and the rectangularity was also inferior to the case of Example 1. Further, in the case of Comparative Example 2 in which exposure and development were performed without using the surface coating composition, the resolution was up to 0.36 μm, but the rectangularity was inferior to that in Example 1.

When the depth of focus was measured, the case where the surface coating composition A was used was the widest, and it was almost the same as the case where the surface coating composition B was used and the case where the surface coating composition was not used. Yes, it was inferior to the case of using the surface coating composition A.

Example 3 and Comparative Example 3 Using quinonediazide positive photoresist (trade name: MCPRi6600) manufactured by Mitsubishi Chemical Corporation and surface coating composition A, a plurality of sheets were prepared in the same manner as in Example 1. Each operation from coating to baking is performed on the wafer, and the photoresist coating film thickness is 10,000 to 12,000Å at intervals of about 100Å.
And the coating thickness of the surface coating composition A is 670Å
A coating film was formed so as to become (Example 3). A wafer having a photoresist coating film formed thereon was prepared for comparison in the same manner as above except that the surface coating composition was not applied (Comparative Example 3).

Then, in the same manner as in Example 1, the operations from exposure to development were carried out. The finished line width of a 0.5 μm mask pattern image at the same exposure amount was measured by an electron microscope. As a result, the change in the finished line width with respect to the change in the film thickness of the photoresist coating film was observed in Example 3 in which the surface coating composition A was used for the exposure and development, without using the surface coating composition. Was much better than Comparative Example 3 in which

Example 4 and Comparative Example 4 A quinonediazide positive photoresist (trade name: MCPRi6600) manufactured by Mitsubishi Chemical Corporation and a surface coating composition D were used, and the coating film thickness of the surface coating composition D was 640Å. Each operation from exposure to development was carried out in the same manner as in Example 1 except that the above was changed (Example 4). Further, a wafer on which a photoresist coating film was formed in the same manner except that the surface coating composition was not applied was prepared for comparison (Comparative Example 4). The resolution, the rectangularity of the pattern, the depth of focus, and the dependence of the pattern size on the photoresist coating film thickness are all the results of Example 4 in which the surface coating composition D was used for exposure and development. The result was better than Comparative Example 4 in which exposure and development were performed without using it.

[0060]

According to the present invention described above, the transfer pattern shape and the depth of focus are excellent at a high resolution by a simple method of applying only one type of surface coating composition, and In addition, a change in transfer pattern dimension due to the coating film thickness is small, and a pattern having a good result can be formed.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03F 7/38 511 G03F 7/38 511 H01L 21/027 H01L 21/30 502R

Claims (6)

[Claims] 1. A coating composition for improving performance in lithography, which is a coating composition used by coating on the upper surface of a coating film of a quinonediazide-based photoresist composition. 2. The coating composition according to claim 1, which is water-soluble. 3. A photosensitive acid generating compound is contained therein.
Or the coating composition according to 2. 4. The coating composition according to claim 1, which contains a fluorine compound. 5. The coating composition according to any one of claims 1 to 4, which contains a compound whose absorbance of the coating composition coating film with respect to the wavelength of the projected light is reduced by the projection of the projected light. 6. A quinonediazide-based photoresist composition coating film coated on a substrate is coated with the coating composition according to claim 1 and projected with light to transfer a pattern latent image. Then, the pattern forming method is characterized by performing heat treatment and then developing.