JP2566169B2 - Positive resist composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a positive resist composition, and more specifically, a positive resist for microfabrication required for manufacturing semiconductor devices, magnetic bubble memory devices, integrated circuits, and the like. The present invention relates to a resist composition.

(Prior Art) When manufacturing a semiconductor, 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, which is then developed to form a negative or positive image. A semiconductor element is formed by a lithographic technique.

Conventionally, as a resist composition for forming a semiconductor element, a negative resist composed of cyclized polyisoprene and a bisazide compound has been known. However, since this negative resist is developed with an organic solvent, it has a large swelling and a limited resolution, so that it has a drawback that it cannot be applied to the production of highly integrated semiconductors. On the other hand, in contrast to this negative resist composition, the positive resist composition is considered to be sufficiently compatible with high integration of semiconductors because of its excellent resolution.

At present, the positive resist composition generally used in this field comprises a novolac resin and a quinonediazide compound.

However, conventional positive resist compositions have not always obtained satisfactory results in various characteristics such as sensitivity, resolution, residual film rate, heat resistance, and storage stability, and improvement in performance is strongly desired. . In particular, sensitivity is important for improving the productivity of semiconductors, and there is a strong demand for higher sensitivity of positive resist compositions. For this purpose, various compounds are added in addition to the novolak resin and the quinonediazide compound, which are base components of the positive resist composition. Examples of compounds added for the purpose of increasing the sensitivity, that is, sensitizers, include nitrogen heterocyclic compounds such as halogenated benzotriazole derivatives (JP-A-58-3764).
1) and cyclic acid anhydrides (Japanese Patent Publication No. 56-30850). However, the addition of these sensitizers eliminates the difference in solubility between the exposed and unexposed areas, and as a result, the residual film rate decreases and the resolution deteriorates, and the plasticizing effect of the novolak resin by the sensitizer is reduced. Therefore, there arises a problem that the heat resistance is lowered.

(Objects to be Solved by the Invention) The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to have various properties such as sensitivity, resolution, residual film rate, heat resistance, and storage stability. A high-sensitivity positive resist composition suitable for fine processing is provided.

(Means for Solving the Problems) This object of the present invention is directed to an alkali-soluble phenolic resin, 4- (1,1-bis (4-hydroxyphenyl) ethyl) -α, α-dimethylbenzyl-4-phenol quinonediazide. Sulfonic acid ester and general formula (I)
This is achieved by a positive resist composition containing a compound represented by

R _{1 to} R ₆ ; same or different, hydrogen, halogen, alkyl group or alkoxy group R ₇ , R ₈ ; same or different, hydrogen, alkyl group or hydroxyalkyl group n = 1, 2, 3 or 4 As the alkali-soluble phenol resin used in, for example, condensation reaction products of phenols and aldehydes, condensation reaction products of phenols and ketones, vinylphenol-based polymers, isopropenylphenol-based polymers, these And a hydrogenation reaction product of a phenol resin.

Specific examples of the phenols used here include phenol, cresol, xylenol, ethylphenol,
Examples include monohydric phenols such as propylphenol, butylphenol, and phenylphenol, and polyhydric phenols such as resorcinol, pyrocatechol, hydroquinone, bisphenol A, and pyrogallol.

Specific examples of aldehydes used here include formaldehyde, acetaldehyde, benzaldehyde, terephthalaldehyde and the like.

Specific examples of the ketones used here include acetone, methyl ethyl ketone, diethyl ketone, diphenyl ketone, and the like.

These condensation reactions can be carried out by a conventional method such as bulk polymerization or solution polymerization.

The vinylphenol polymer is selected from vinylphenol homopolymers and copolymers of vinylphenol and copolymerizable components. Specific examples of the copolymerizable component include acrylic acid derivative, methacrylic acid derivative, styrene derivative, maleic anhydride, maleic imide derivative, vinyl acetate, acrylonitrile and the like.

The isopropenylphenol-based polymer is selected from isopropenylphenol homopolymers and copolymers with a component copolymerizable with isopropenylphenol. Specific examples of the copolymerizable component include acrylic acid derivative, methacrylic acid derivative, styrene derivative, maleic anhydride, maleic imide derivative, vinyl acetate, acrylonitrile and the like.

The hydrogenation reaction of these phenol resins can be carried out by any known method, and the phenol resin is dissolved in an organic solvent and hydrogen is introduced in the presence of a homogeneous or heterogeneous hydrogenation catalyst. Can be achieved by doing.

As these alkali-soluble phenol resins, those whose molecular weight distribution is controlled by reprecipitation separation or the like can be used. Further, although these phenol resins may be used alone, two or more kinds may be mixed and used.

The positive resist composition of the present invention, if necessary, in order to improve developability, storage stability, heat resistance, etc., for example, a copolymer of styrene and acrylic acid, methacrylic acid or maleic anhydride, A copolymer of an alkene and maleic anhydride, a vinyl alcohol polymer, a vinyl pyrrolidone polymer, rosin, shellac and the like can be added. The amount of addition is 100 above alkali-soluble phenol resin
The amount is 0 to 50 parts by weight, preferably 5 to 20 parts by weight.

The photosensitizer used in the present invention is not particularly limited as long as it is a quinonediadiosulfonic acid ester of 4- (1,1-bis (4-hydroxyphenyl) ethyl) -α, α-dimethylbenzyl-4-phenol. Not something.
As specific examples thereof, the ester moiety is 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,1 Examples include compounds such as naphthoquinonediazide-4-sulfonic acid ester, 2,1-naphthoquinonediazide-5-sulfonic acid ester, and sulfonic acid esters of other quinonediazide derivatives.

The photosensitizer in the present invention can be synthesized by an esterification reaction of a quinonediazide sulfonic acid compound, and is described in “Photosensitive Polymer” by Mototaro Nagamatsu and Hideo Inui (198
0) It can be synthesized according to a conventional method described in Kodansha (Tokyo).

The sensitizers in the present invention may be used alone, or two or more kinds may be mixed and used. The compounding amount of the photosensitizer is 1 to 100 parts by weight, preferably 3 to 40 parts by weight, based on 100 parts by weight of the resin. If it is less than 1 part by weight, it becomes impossible to form a pattern, and if it exceeds 100 parts by weight, residual images tend to remain.

The sensitizer used in the present invention is not particularly limited as long as it is a compound represented by the general formula (I).

Specific examples of the compound represented by formula (I) include the following.

The sensitizer in the present invention may be used alone,
You may use it in mixture of 2 or more types. The compounding amount of the sensitizer is 100 parts by weight or less, preferably 2 to 50 parts by weight, based on 100 parts by weight of the resin. If the amount of the additive exceeds 100 parts by weight, the residual film rate will be drastically reduced and pattern formation will be difficult.

The positive resist composition of the present invention is used by dissolving it in a solvent. As the solvent, ketones such as acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol are used. , Alcohols such as cyclohexanol, ethylene glycol methyl ether, ethylene glycol diethyl ether, ethers such as dioxane, ethylene glycol monomethyl ether,
Alcohol ethers such as ethylene glycol monoethyl ether, propyl formate, butyl formate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl lactate, esters such as ethyl lactate, cellosolve acetate, Cellosolve esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate, propylene glycols such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether. , Diethylene glycol monomethyl ether, diethylene glycol Over monoethyl ether, diethylene glycol such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, halogenated hydrocarbons such as trichlorethylene, toluene, aromatic hydrocarbons such as xylene, dimethylacetamide,
Examples thereof include polar solvents such as dimethylformamide and N-methylacetamide. You may use these individually or in mixture of 2 or more types.

The positive resist composition of the present invention may contain, if necessary, compatible additives such as a surfactant, a storage stabilizer, a sensitizer, a striation inhibitor, a plasticizer, and an antihalation agent. Can be.

As a developer for the positive 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, ethylamine, propylamine, and the like are used. Primary amines, secondary amines such as diethylamine and dipropylamine, tertiary amines such as trimethylamine and triethylamine, diethylethanolamine,
Alcohol amines such as triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide, and trimethylhydroxyethylammonium hydroxide. Can be

Furthermore, if necessary, an appropriate amount of a water-soluble organic solvent such as methanol, ethanol, propanol, or ethylene glycol, a surfactant, a storage stabilizer, a resin dissolution inhibitor, etc. can be added to the above alkaline aqueous solution.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples.

Comparative Example 1 m-cresol and p-cresol were mixed at a molar ratio of 4: 6, formalin was added to the mixture, and 100 parts by weight of a novolak resin obtained by condensation by an ordinary method using an oxalic acid catalyst, 2 7 of 3,3,4,4'-tetrahydroxybenzophenone
28% by weight of a quinonediazide compound, 5% of which is an ester of 1,2-naphthoquinonediazide-5-sulfonic acid, is dissolved in 350 parts by weight of ethyl cellosolve acetate and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter to obtain a resist solution. Was prepared.

The resist solution was applied onto a silicon wafer with a coater and baked at 100 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer is a g-line stepper
Exposure was performed using NSR-1505G6E (manufactured by Nikon Corporation, NA = 0.54) and a test reticle. Next, it was developed by a 2.38% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 1 minute by the paddle method to obtain a positive pattern.

The sensitivity was evaluated to be 120 mJ / cm ² , and the film thickness of the pattern was measured to be 1.12 μm by a film thickness meter Alphastep 200 (manufactured by Tenko Co.).

Comparative Example 2 m-Cresol, p-cresol and 3,5-xylenol were mixed at a molar ratio of 50:20:30, formalin was added to the mixture, and condensed by an ordinary method using an oxalic acid catalyst. 100 parts by weight of novolak resin, 28% by weight of quinonediazide compound in which 95% of 2,3,4,4'-tetrahydroxybenzophenone is an ester of 1,2-naphthoquinonediazide-5-sulfonic acid dissolved in 360% by weight of ethyl lactate Then 0.1 μm
A PTFE filter was used to prepare a resist solution.

The resist solution was coated on a silicon wafer with a coater and then baked at 90 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer is g-line stepper NS
Exposure was performed using the R-1505G6E and a test reticle.
Then, this wafer was subjected to PEB at 110 ° C. for 60 seconds and then developed with a 2.38% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 1 minute by a paddle method to obtain a positive pattern.

As a result of taking out and evaluating the patterned wafer, the sensitivity was 160 mJ / cm ² , and the film thickness meter Alpha Step 2
The residual film thickness measured at 00 was 1.13 μm.

Example 1 100 parts by weight of novolak resin obtained by mixing m-cresol and p-cresol at a molar ratio of 7: 3, adding formalin thereto, and condensing by a conventional method using an oxalic acid catalyst, Tris 90% of Phenol PA (Mitsui Petrochemical)
35 parts by weight of a quinonediazide compound, which is an ester of 1,2-naphthoquinonediazide-5-sulfonic acid, and 7 parts by weight of a sensitizer represented by the formula (20) were dissolved in 350 parts by weight of ethyl cellosolve acetate, and filtered with a 0.1 μm PTFE filter. A resist solution was prepared by filtration.

The resist solution was applied onto a silicon wafer with a coater and baked at 100 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer is an i-line stepper
Exposure was performed using a NSR-1505i6A (manufactured by Nikon Corporation, NA = 0.45) and a test reticle. Next, this wafer is 110 ℃
After PEB for 60 seconds at 23 ° C., a positive pattern was obtained by developing with a 2.38% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 1 minute by the paddle method.

When the patterned wafer was taken out and the sensitivity was evaluated, it was 140 mJ / cm ² , and when observed with an electron microscope, 0.40 μm lines and spaces were resolved. The film thickness of the pattern was 1.15 μm when measured with a film thickness meter Alpha Step 200.

Example 2 Copolymer of vinylphenol and styrene (molar ratio 5:
5) 100 parts by weight, Trisphenol PA (Mitsui Petrochemical)
36 parts by weight of a quinonediazide compound, 90% of which is an ester of 1,2-naphthoquinonediazide-5-sulfonic acid, (3
A resist solution was prepared by dissolving 5 parts by weight of the sensitizer represented by the formula (0) in 320 parts by weight of diglyme and filtering with a 0.1 μm PTFE filter.

The resist solution was applied onto a silicon wafer with a coater and baked at 100 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer is an i-line stepper
Exposure was performed using NSR-1505i6A and a test reticle. Then, PEB the wafer at 110 ° C. for 60 seconds, and then 2.38
% Tetramethylammonium hydroxide aqueous solution 23
Developed by paddle method at ℃ for 1 minute to obtain positive pattern.

When the wafer on which the pattern was formed was taken out and the sensitivity was evaluated, it was 90 mJ / cm ² , and when observed by an electron microscope, 0.50 μm lines and spaces were resolved. The film thickness of the pattern was 1.12 μm when measured with a film thickness meter Alpha Step 200.

Example 3 100 parts by weight of novolak resin obtained by mixing m-cresol and p-cresol at a molar ratio of 5: 5, adding formalin thereto, and condensing by a conventional method using an oxalic acid catalyst. 9 of 3,3,4,4'-tetrahydroxybenzophenone
14 parts by weight of a quinonediazide compound, 5% of which is an ester of 1,2-naphthoquinonediazide-5-sulfonic acid, and 90% of trisphenol PA (manufactured by Mitsui Petrochemicals) is an ester of 1,2-naphthoquinonediazide-4-sulfonic acid. Was dissolved in 380 parts by weight of ethyl lactate and filtered with a 0.1 μm PTFE filter to prepare a resist solution.

The resist solution was applied onto a silicon wafer with a coater and baked at 100 ° C. for 90 seconds to form a resist film having a thickness of 1.17 μm. This wafer is an i-line stepper
Exposure was performed using NSR-1505i6A and a test reticle. Then, PEB the wafer at 110 ° C. for 60 seconds, and then 2.38
23% with an aqueous solution of tetramethylammonium hydroxide
Developed by paddle method at ℃ for 1 minute to obtain positive pattern.

When the patterned wafer was taken out and the sensitivity was evaluated, it was 120 mJ / cm ² , and when observed by an electron microscope, 0.40 μm lines and spaces were resolved. The film thickness of the pattern was 1.14 μm when measured with a film thickness meter Alpha Step 200.

(Effects of the Invention) Since the positive resist composition of the present invention is excellent in sensitivity, resolution, residual film rate, heat resistance, storage stability, etc., it is particularly useful for fine processing of 1 μm or less.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-10646 (JP, A) JP 60-237439 (JP, A) JP 63-88546 (JP, A) JP 1- 105243 (JP, A) JP 62-227144 (JP, A) JP 60-189739 (JP, A) JP 57-86830 (JP, A) JP 3-48249 (JP, A)

Claims (1)

(57) [Claims] 1. An alkali-soluble phenolic resin, 4- (1,
1-bis (4-hydroxyphenyl) ethyl) -α, α
-A positive resist composition comprising a quinonediazide sulfonic acid ester of dimethylbenzyl-4-phenol and a compound represented by the general formula (I). R1 to R6; same or different, hydrogen, halogen, alkyl group or alkoxy group R7, R8; same or different, hydrogen, alkyl group or hydroxyalkyl group n = 1, 2, 3 or 4