JP2618692B2 - Resist composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resist material for fine processing of a semiconductor device, and more particularly to a pattern forming material by irradiation with far ultraviolet light, KrF excimer laser light or the like. is there.

(Prior art) When manufacturing a semiconductor device, a resist is applied to the surface of a silicon wafer to form a photosensitive film, which is irradiated with light to form a latent image, and then developed to form a negative or positive image. The image is obtained by lithography technology.

However, with the increasing integration, density, and miniaturization of semiconductor elements in ICs, LSIs, and VLSIs, a technique for forming a fine pattern of 1 μm or less is required. However,
It is extremely difficult to accurately form a pattern of 1 μm or less by a conventional method using ordinary photolithography using near ultraviolet light or visible light. At the same time, the yield is remarkably reduced. Therefore, the method using ordinary photolithography is not suitable for forming a pattern of 1 μm or less.
I can not cope.

Therefore, instead of conventional photolithography using light (ultraviolet light having a wavelength of 350 to 450 nm), a lithography technique using far ultraviolet rays, KrF excimer laser light, or the like having a shorter wavelength has been studied.

There are a wide range of requirements for the resist material, which is the center of this lithography technology, such as sensitivity, resolution, etching resistance, and storage stability. Conventionally developed materials satisfy all of these requirements. Rather, improvements in performance are strongly desired.

For example, a negative resist such as polyglycidyl methacrylate has high sensitivity, but has poor resolution and dry etching resistance, and is desired to be improved. Positive resists such as poly (methyl methacrylate) have good resolution, but are inferior in sensitivity and dry etching resistance, which is a practical problem. In addition, when a novolak-based positive photoresist used in conventional photolithography is exposed to far ultraviolet light, a good pattern cannot be formed because the resist itself absorbs too much light. Therefore, the development of a balanced new resist has been strongly desired.

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to balance the general resist characteristics such as sensitivity, resolution, etching resistance and storage stability, especially for short wavelengths. An object of the present invention is to provide a resist material suitable for lithography using far ultraviolet rays and KrF excimer laser light.

The object of the present invention (Means for Solving the Problem) is, -C benzene ring of the alkali-soluble phenolic resin = C- bond partially -CH ₂ -CH ₂ -
For deep ultraviolet or KrF excimer laser light exposure, comprising an alkali-soluble hydrogenated product converted to and a photosensitive compound, and wherein the alkali-soluble phenol resin has a structural unit represented by the following formula: This is achieved by a resist composition.

R ¹ , R ² : same or different hydrogen atom, alkyl group, aryl group, aralkyl group, alkenyl group, halogen The hydrogenated product of the alkali-soluble phenol resin used in the present invention is a hydrogenated product having a structural unit represented by the above formula. It is obtained by partially hydrogenating the union.

The monomer that provides the structural unit of the above formula used in the present invention is not particularly limited, but specific examples are o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene.
Hydroxystyrene, 3-chloro-4-hydroxystyrene, 3,5-dichloro-4-hydroxystyrene, 3-bromo-4-hydroxystyrene, 3,5-dibromo-4-hydroxystyrene, 4-chloro-3-hydroxy Styrene, 4-bromo-3-hydroxystyrene, 3-ethyl-4-hydroxystyrene, 3-propyl-4-hydroxystyrene, 3-tbutyl-4-hydroxystyrene, 3,5-diethyl-4-hydroxystyrene, 3,5-dipropyl-4-hydroxystyrene, 3,5-di-tbutyl-4-hydroxystyrene, 3-phenyl-4-hydroxystyrene, 3-naphthyl-4-hydroxystyrene, 3-benzyl-4-hydroxystyrene , 3-styryl-4-hydroxystyrene, 3,5-dibenzyl-4-hydroxys Len, 3,5-distyryl-4-hydroxystyrene, 3-vinyl-4-hydroxystyrene, 3-propenyl-4-hydroxystyrene, 4-vinyl-3-hydroxystyrene, 4-propenyl-3-hydroxystyrene, etc. Is mentioned.

The alkali-soluble resin used in the present invention may be a copolymer further containing, as a copolymer component, another monomer copolymerizable with the polymer giving the structural unit of the above formula.

The other monomer is not particularly limited, but specific examples include acrylic acid, methyl acrylate,
Acrylic acid derivatives such as ethyl acrylate, glycidyl acrylate and propyl acrylate, styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, chloromethylstyrene, maleic anhydride derivatives, vinyl acetate, vinylpyridine, acrylonitrile, etc. Is mentioned.

As the other copolymerizable monomer, the monomer providing the structural unit represented by the above formula can be used in the range of 0 to 50 mol% as long as the alkali developability is not impaired. .

The hydrogenation reaction of the alkali-soluble phenol resin can be performed by any known method, and the alkali-soluble phenol resin is dissolved in an organic solvent, and a homogeneous or heterogeneous hydrogenation catalyst is present. Below, this is achieved by introducing hydrogen. The concentration of the alkali-soluble phenol resin solution is 1 to 70% by weight.
Preferably it is 1 to 40% by weight. The solvent is not particularly limited as long as it does not adversely affect the catalyst and dissolves the resin subjected to the hydrogenation reaction. The hydrogenation catalyst used in the present invention is not particularly limited as long as it is a metal or nonmetal catalyst having the activity of a hydrogenation reaction. Specific examples include Fe, Co, Ni, Ru, Rh, Pd, Ir, Os, Pt, Cr, Te, Mn, T
i, V, Zr, Mo, W and the like. These catalysts can be used alone or in combination. Reaction temperature is 0-30
0 ° C., preferably 20 to 150 ° C. Although a temperature of 300 ° C. or higher may be acceptable, a side reaction occurs, which is not preferable in the hydrogenation reaction. The reaction hydrogen pressure ranges from atmospheric pressure to 400 kg / cm ² , preferably from 5 to 200 kg / cm ² .

After the hydrogenation reaction, the catalyst can be removed from the hydrogenation reaction resin solution by reprecipitation purification, sedimentation, centrifugation, filtration, or the like.

The photosensitive compound used in the present invention is described in "Photosensitive Polymers" (1980) by Kotaro Nagai and Hideo Inui (1980), Kodansha (Tokyo), and "Photoresist" (1975) by Deforest, McGraw-Hill Incorporated (New York). Is not particularly limited as long as it is satisfied. Specific examples thereof include 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, and 2,1-naphthoquinonediazide. -4-sulfonic acid ester, 2,1-naphthoquinonediazide-5-sulfonic acid ester, 2-diazo-cyclohexane-1,3-dione, 5-diazo-meldrum acid ester, 3-diazo-pyrrolidine-2,4- Diazoketone compounds such as dione, 3-diazo-piperidine-2,4-dione, diazophosphenylketone compound or derivatives thereof; 0-nitrobenzyl ester, 0-nitrobenzylsulfonic acid ester, 0,0-dinitrobenzyl ester, 0-nitrobenzyl compound such as 0,0-dinitrobenzylsulfonic acid ester Substances; iodonium salts, phosphonium salts, sulfonium salts,
Onium salts such as ammonium salts; monoazide compounds such as 1-azidopyrene, p-azidobenzophenone, 4'-methoxy-4-azidodiphenylamine, 4-azidobenza-2'-methoxyacetophenone, 4-azido-4'-nitrophenylazobenzene 4,4'-diazidobenzophenone, 4,4'-diazidobenzomethane, 4,4'-diazidostilbene, 4,4'-diazidochalcone, 4,4'-diazidodiphenylsulfone, 3, Bisazide compounds such as 4'-diazidodiphenylsulfone, 3,3'-diazidodiphenylsulfone, 2,6-di (4'azidobenzal) cyclohexanone, 2,6-di (4'azidobenzal) 4-methylcyclohexanone; mono Sulfonyl azide compound; bissulfonyl azide compound and the like.

The amount of these photosensitive compounds is 1 to 100 parts by weight, preferably 3 to 30 parts by weight, per 100 parts by weight of the polymer.
Parts by weight. If the amount is less than 1 part by weight, pattern formation becomes impossible, and if it exceeds 100 parts by weight, development residue tends to occur.

The resist composition of the present invention is used by dissolving the hydrogenated alkali-soluble phenol resin and the photosensitive compound in a solvent. Examples of the solvent include ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethylene glycol monomethyl ether and ethylene glycol. Examples include glycol ethers such as monoethyl ether, cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate, and aromatic hydrocarbons such as toluene and xylene. These may be used alone or in combination of two or more.

Further, the resist composition of the present invention, if necessary,
Surfactants, storage stabilizers, sensitizers, striation inhibitors and the like can also be added.

As a developing solution for the resist composition of the present invention, an aqueous alkali solution is used. Specifically, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate, and ammonia; Amines, secondary amines such as diethylamine and dipropylamine, tertiary amines such as trimethylamine and triethylamine, alcoholamines such as diethylethanolamine and triethanolamine, tetramethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide And quaternary ammonium salts such as tetraethylammonium hydroxide.

If necessary, a suitable amount of a water-soluble organic solvent such as methanol, ethanol, propanol, or ethylene glycol, a surfactant, or a dissolution inhibitor for a resin can be added to the aqueous alkali solution.

(Example) Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, parts and% are based on weight unless otherwise specified.

Synthesis Example 1 An autoclave was charged with 50 g of a vinylphenol polymer (hereinafter abbreviated as PVP) and 450 g of ethanol, and mixed well to dissolve the polymer. Then added Raney Ni4g, the inside of the system was replaced with nitrogen, a hydrogen pressure of 50 kg / cm ² cloves while maintaining the 20 ° C.
Hold for 30 minutes. Thereafter, the autoclave was placed in a warm bath at 50 ° C. and reacted for 3 hours. Raney Ni from solution after reaction
Was separated by filtration, and the reaction solution was poured into water to precipitate a polymer. Further, the obtained polymer was dissolved in ethanol and poured into water to precipitate the polymer. Next, this polymer was dissolved in dioxane and freeze-dried for 36 hours to obtain a dried polymer. The yield was 90%.

As a result of gel permeation chromatography (GPC) measurement of the above polymer, Mw was 3000, and as a result of nuclear magnetic resonance spectrum (NMR) measurement, the hydrogenation ratio was 40%. As a result of UV spectrum measurement, the transmittance of hydrogenated PVP at 250 nm was improved about twice as compared with the raw material PVP.

Synthesis Example 2 An autoclave was charged with 50 g of a copolymer of 80 mol% of vinylphenol and 20 mol% of styrene (hereinafter abbreviated as PVP / St) and 450 g of ethanol, and mixed well to dissolve the polymer. Next, 3 g of Raney Ni was added, and the inside of the system was purged with nitrogen. Then, while maintaining the temperature at 20 ° C., the hydrogen pressure was maintained at 50 kg / cm ² for 30 minutes. Then place the autoclave in a 40 ° C
Allowed to react for hours. Raney Ni is filtered off from the solution after the reaction,
The reaction solution was poured into water to precipitate a polymer. Further, the obtained polymer was dissolved in ethanol and poured into water to precipitate the polymer. Next, this polymer was dissolved in dioxane and freeze-dried for 40 hours to obtain a dried polymer. The yield was 95%.

As a result of gel permeation chromatography (GPC) measurement of the above polymer, Mw was 8000, and as a result of nuclear magnetic resonance spectrum (NMR) measurement, the hydrogenation ratio was 20%. Further, as a result of the measurement of the UV spectrum, the transmittance of the hydrogenated PVP / St at 250 nm was improved about twice as compared with the raw material PVP / St.

Example 1 100 parts of hydrogenated PVP of Synthesis Example 1, 20 parts of a quinonediazide compound in which 70% or more of the -OH groups of 2,3,4-trihydroxybenzophenone are 1,2-naphthoquinonediazide-4-sulfonic acid esters The ethyl cellosolve acetate 40
The solution was dissolved in 0 parts and filtered through a 0.1 μm Teflon filter (Millipore) to prepare a resist solution.

The resist solution was applied on a silicon wafer by a spinner, and baked at 85 ° C. for 20 minutes to form a resist film having a thickness of 0.9 μm. This wafer is irradiated with far ultraviolet light
Exposure was performed using PLA-521FA (manufactured by Canon Inc.) and a test mask. Next, development was performed with an aqueous tetramethylammonium hydroxide solution at 23 ° C. for 1 minute by an immersion method to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.4 μm was resolved. When the film thickness of the pattern was measured with a film thickness meter Alpha Step 200 (manufactured by Tenko), it was 0.8 μm.

Further, the wafer on which this pattern was formed was subjected to dry etching equipment DEM-451T (manufactured by Nidec Anelva), power 300 W, pressure 0.03 Torr, gas CF ₄ / H = 30/10, frequency
When etching was performed at 13.56 MHz, it was observed that etching was performed only where there was no pattern.

Example 2 100 parts of hydrogenated PVP / St of Synthesis Example 2, 2-diazo-
12 parts of cyclohexanone-1,3-dione was dissolved in 400 parts of ethyl cellosolve acetate, and the solution was filtered through a 0.1 μm Teflon filter to prepare a resist solution.

The resist solution was applied on a silicon wafer by a spinner, and baked at 75 ° C. for 10 minutes to form a 1.0 μm thick resist film. This wafer is irradiated with far ultraviolet light
Exposure was performed using PLA-521FA and a test mask. Next, 23 with an aqueous solution of tetramethylammonium hydroxide
The film was developed by immersion at ℃ for 1 minute to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.8 μm.

Example 3 Hydrogenated PVP (Mw600) prepared in the same manner as in Synthesis Example 1
0, hydrogenation rate 30%) 100 parts, 25 parts of 5-diazomeldrum acid are dissolved in 400 parts of ethyl cellosolve acetate, and 0.1 μm
Was filtered through a Teflon filter to prepare a resist solution.

The resist solution was applied on a silicon wafer with a spinner and baked at 70 ° C. for 10 minutes to form a 0.8 μm thick resist film. This wafer is irradiated with far ultraviolet light
Exposure was performed using PLA-521FA and a test mask. Next, 23 with an aqueous solution of tetramethylammonium hydroxide
The film was developed by immersion at ℃ for 1 minute to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.7 μm.

Example 4 100 parts of PVP, 18 parts of 0,0'-dinitrocholate and 0.02 part of a fluorinated surfactant used in Example 1 were dissolved in 400 parts of cyclohexanone, and filtered through a 0.1 μm Teflon filter to prepare a resist solution. did.

The resist solution was applied on a silicon wafer with a spinner and baked at 80 ° C. for 10 minutes to form a resist film having a thickness of 0.9 μm. This wafer is irradiated with far ultraviolet light
Exposure was performed using PLA-521FA and a test mask. Next, 23 with an aqueous solution of tetramethylammonium hydroxide
The film was developed by immersion at ℃ for 1 minute to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.7 μm.

Example 5 100 parts of hydrogenated PVP and 10 parts of diphenyliodonium tetrafluoroborate of Synthesis Example 1 were dissolved in 400 parts of ethyl cellosolve acetate, and filtered with a 0.1 μm Teflon filter to prepare a resist solution.

The resist solution was applied on a silicon wafer by a spinner, and baked at 80 ° C. for 10 minutes to form a resist film having a thickness of 1.0 μm. The wafer was exposed using an excimer laser apparatus C2926 (manufactured by Hamamatsu Photonics) filled with a krypton / fluorine gas and a test mask. Next, development was performed with an aqueous tetramethylammonium hydroxide solution at 23 ° C. for 1 minute by an immersion method to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.9 μm.

Example 6 100 parts of hydrogenated PVP of Synthesis Example 1, 19 parts of a quinonediazide compound in which 70% of the -OH group of 2,3,4-trihydroxyacetophenone is an ester of 1,2-naphthoquinonediazide-4-sulfonic acid, 0.02 parts of a fluorinated surfactant was dissolved in 400 parts of cyclohexanone, and filtered through a 0.1 μm Teflon filter to prepare a resist solution.

The resist solution was applied on a silicon wafer by a spinner, and baked at 80 ° C. for 10 minutes to form a resist film having a thickness of 1.0 μm. The wafer was exposed using an excimer laser apparatus C2926 filled with a krypton / fluorine gas and a test mask. Next, development was performed with an aqueous tetramethylammonium hydroxide solution at 23 ° C. for 1 minute by an immersion method to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.7 μm.

Example 7 Hydrogenated PVP (Mw800) prepared in the same manner as in Synthesis Example 1
0, hydrogenation rate 20%) Dissolve 100 parts, 4,4'-diazidediphenylsulfone, 12 parts and fluorine-based surfactant 0.02 parts in 400 parts of cyclohexanone, and filter with a 0.1 μm Teflon filter to prepare a resist solution. did.

The resist solution was applied on a silicon wafer by a spinner, and baked at 80 ° C. for 10 minutes to form a resist film having a thickness of 1.0 μm. This wafer was exposed using an excimer laser apparatus C2926 filled with krypton / nitrogen gas and a test mask. Next, development was performed with an aqueous tetramethylammonium hydroxide solution at 23 ° C. for 1 minute by an immersion method to obtain a negative pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, a line and space of 0.45 μm was resolved. When the film thickness of the pattern was measured by a film thickness meter Alpha Step 200, it was 0.9 μm.

Comparative Example 1 An ordinary commercially available novolak-based positive photoresist was applied on a silicon wafer with a spinner, and baked at 85 ° C. for 15 minutes to form a 1.0 μm thick resist film. The wafer was exposed using an excimer laser apparatus C2926 filled with a krypton / fluorine gas and a test mask. Next, development was performed with an aqueous tetramethylammonium hydroxide solution at 23 ° C. for 1 minute by an immersion method to obtain a positive pattern.

When the wafer on which the pattern was formed was taken out and observed with an electron microscope, it was found that the line and space of 0.55 μm had been resolved. However, the line was severely narrowed, the pattern was poor in shape, and there was a practical problem.

Comparative Example 2 100 parts of raw material PVP of hydrogenated PVP of Example 7, 12 parts of 4,4'-diazide diphenyl sulfone, fluorine-based surfactant 0.02
Was dissolved in 400 parts of cyclohexanone and filtered through a 0.1 μm Teflon filter to prepare a resist solution.

Patterning was performed in the same manner as in Example 7, and the wafer on which the pattern was formed was taken out and observed with an electron microscope. As a result, a line and space of 0.65 μm was resolved, but the shape of the pattern was defective. .

(Effect of the Invention) According to the present invention, it is possible to obtain a resist excellent in sensitivity, resolution, etching resistance, storage stability and the like, and particularly suitable for lithography using short-wavelength light.

Claims (1)

(57) [Claims] 1. An alkali-soluble phenolic resin comprising an alkali-soluble hydrogenated product obtained by partially converting a --C ＝ C-- bond of a benzene ring into --CH ₂ --CH _2- and a photosensitive compound; A resist composition for exposure to far ultraviolet rays or KrF excimer laser light, wherein the soluble phenolic resin has a structural unit represented by the following formula. R ¹ , R ² : same or different hydrogen atom, alkyl group, aryl group, aralkyl group, alkenyl group, halogen