JPH06273933A - Positive radiation sensitive resin composition and transferred pattern obtained from this - Google Patents

Abstract

PURPOSE:To obtain the resin composition which is affected by far-ultraviolet rays, electron beam. X rays, etc., and excellent in the stability until heattreatment after radiation by containing a compound having an epoxypropyl or epoxy group in a composition. CONSTITUTION:In the chemical amplification series positive radiation sensitive resin composition containing the acid forming anent which generates acid at the time of being exposed to radioactive rays, the composition is incorporated with the compd. having epoxypropyl or epoxy group. The example of the compd. having epoxypropyl or epoxy group is 1, 2-epoxy-3-phenoxypropane, 2, 3- epoxypropyl-4methoxyphenyl ether, 2, 3-epoxypropyl benzene, etc,. The chemical amplification series positive radiation sensitive resin composition is the one component type resist imparted an acid forming state in the resin by the composition. the two component type resist imparted acid-decomposition property and the the three component type resist consisting of a alkali-soluble resin, an acid-decomposition compd. and the acid forming agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive-type radiation-sensitive resin composition and a pattern obtained from it, and more particularly to deep ultraviolet rays used in the manufacture of semiconductor integrated circuits such as IC and LSI and masks. The present invention relates to a positive-type radiation-sensitive resin composition sensitive to radiation such as electron beams and X-rays, and a transfer pattern obtained from the same.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductor integrated circuits and the like, a resist is coated on a substrate such as a silicon wafer, irradiated with radiation through a mask, and further developed to form a fine pattern, and then a pattern is formed. Etching is performed on the substrate portion other than the portion. In recent years, in order to improve the performance and reliability of integrated circuits, there is an increasing demand for higher density of elements. Positive resists and negative resists are known as current resists.

As a negative resist sensitive to radiation such as deep ultraviolet rays, electron beams, and X-rays, a chloromethylated polystyrene having polystyrene as a trunk polymer or a resin composition containing chlorinated polymethylstyrene is known. In order to increase the resolution, development treatment with an alkaline aqueous solution is generally advantageous, but these compositions have high sensitivity and excellent dry etching resistance, but since the development treatment with an organic solvent is performed, the transfer pattern is distorted due to the influence of swelling. However, it has a drawback that the resolution is poor due to peeling of the film.

Polymethyl methacrylate and polyolefin sulfone are known as positive type resists. The former has excellent resolution but very low sensitivity, and the latter has high sensitivity but cannot be dry etched. Have Also U.S. Pat. No. 4,339,522 and Chemische Berichte 92,1.
Attempts have been made to utilize oxydiazo compounds such as Meldrum's acid and dimedone disclosed in 30 (1959) as a positive resist. These compositions have good resolution in an alkaline developer and have no problem with dry etching resistance, but have the disadvantage that they are unstable with respect to thermal load and sublimate during the prebaking to lose a considerable amount. is there.

As a method for solving the above problems in positive resist, a chemically amplified resist was proposed by Ito et al. Of IBM (ACS Symp. Ser., 24).
2, 11 (1984). Chemical amplification means adding a compound that generates an acid by radiation to a resist, and then polymerizing, depolymerizing, using the catalytic reaction of the acid generated by radiation.
In this method, the reaction such as desorption is promoted by heat treatment to increase the sensitivity of the resist.

The chemically amplified resist is a positive type consisting of a compound in which a hydroxyl group of polyvinylphenol resin is partially substituted with a tertiary butoxycarbonyl group and a compound which generates an acid by radiation (hereinafter referred to as an acid generator). There is known a resist and a positive resist including polyvinyl tert-butyl benzoate and an acid generator (Japanese Patent Publication No. 27660/1990).

The resist is composed of two components, a resin having an acid decomposability and an acid generator. In addition to the above, the resin, the acid decomposable compound and the acid generating compound which have the acid decomposability as a third compound. A three-component resist composed of an agent (for example, JP-A-63-250642) or a one-component resist having all the functions in the same molecule (for example, JP-A-2-2401).
14) etc.

As semiconductors have become highly integrated, there have been problems such as shortening of the irradiation wavelength and incidental light absorption of the resist at the irradiation wavelength. However, the chemically amplified resist has the above-mentioned acid-catalyzed reaction. It seemed that these problems were solved by using them. However, a chemically amplified resist is one in which an acid is generated by radiation and the reaction between the generated acid and a radiation-sensitive group (acid-decomposable group) is catalytically amplified by heat treatment. In the above, there was a problem that the acid generated between the irradiation and the heat treatment was deactivated with time.

Regarding the cause of this inactivation, the effect of amine, oxygen, water, impurities, etc. in the air is reported [J. P
photopolym. Sci. Tech. , 4,299
(1991): SPIE Vol. 1672, 24 (1
992)], but the details are still unknown. There is a demand for a stable resist that does not suffer from environmental influences after irradiation and before heat treatment.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fine processing positive resist which is sensitive to radiation such as deep ultraviolet rays, electron rays, X-rays and the like and is excellent in stability after irradiation and heat treatment. To do.

[0011]

The inventors of the present invention have accomplished the present invention as a result of intensive studies to solve the above-mentioned problems. That is, the present invention is a chemically amplified positive-working radiation-sensitive resin composition containing an acid generator that produces an acid when exposed to radiation, wherein the composition contains an epoxypropyl group or a compound having an epoxy group. Another object of the present invention is to provide a positive-type radiation-sensitive resin composition characterized by the above, and a transfer pattern obtained from this resin composition.

The positive type radiation sensitive resin of the present invention will be described in detail below. Specific examples of the compound having an epoxypropyl group and the compound having an epoxy group used in the positive-type radiation-sensitive resin composition of the present invention include 1,2-epoxy-3-phenoxypropane and 2,3-epoxypropyl. 4-methoxyphenyl ether, 2,3-epoxypropyl benzene, N- (2,3-epoxypropyl) phthalimide, 2,3-epoxypropylfurfuryl ether, 2,3-epoxypropyl methacrylate, 2,3-epoxypropylbiphenyl ether,
2,3-epoxypropyl alpha naphthyl ether, 1,2
-Epoxy octadecane, 4- (2,3-epoxyhexyloxy) phenyl 4- (decyloxy) benzoate, 2,3-epoxynorbornane, 1,4-epoxy-1,2,3,4-tetrahydronaphthalene, 3,6 −
Epoxy-1,2,3,6-tetrahydrophthalic hydride, 3,4-epoxytetrahydrothiophene-1,1-dioxide, 1,2-epoxy-5
9-cyclododecadiene, 1,8-cineole, cineolic acid, α-phenyl-α ′-(4-methoxyphenyl) ethylene oxide, α-phenyl-α-
Examples thereof include (2-hydroxyphenyl) ethylene oxide, but are not limited thereto.

As the chemically amplified positive-working radiation-sensitive resin, as described above, a one-component resist having an acid generating state and an acid decomposing performance in the resin or an alkali-soluble resin having an acid decomposing performance depending on its composition is used. There are two-component resists composed of an acid generator and three-component resists composed of an alkali-soluble resin, an acid decomposable compound and an acid generator.

For example, as a resin used in the three-component positive-working radiation-sensitive resin composition, an alkali-soluble resin that can be developed in an alkaline aqueous solution is used. Specific examples include phenol novolac resin, cresol novolac resin, and polyvinyl resin. Examples thereof include, but are not limited to, phenol, a partially nuclear hydrogenated resin of polyvinylphenol, methyl (meth) acrylate- (meth) acrylic acid copolymer, and styrene-maleic acid copolymer.

The acid-decomposable compound is a compound in which a hydroxyl group of a phenolic compound or a carboxyl group of an aromatic compound is protected with a tertiary butoxycarbonyl (t-BOC) group or a tertiary butyl group, specifically, bisphenol-A. T-BO
C compounds, tertiary butyl ester of naphthalene β-carboxylic acid, silyl ether polymer and the like can be mentioned (Semi
con News 1989 12 p. 27) is not limited to these.

Examples of the acid generator include onium salts such as sulfonium salts, iodonium salts, arsonium salts and diazonium salts, and sulfonic acid ester compounds. Specific examples of these compounds include Journal of of
PhotopolymerScience and
Technology, 2 (2), p. 283-284
(1989), it is described as a photoacid generator, but is not limited thereto.

The content ratio of each component in the present invention is, for example, in the case of a three-component resist, when the total solid content is 100 parts by weight, the alkali-soluble resin is 60 to 90 parts by weight, preferably 65 to 85 parts by weight, The acid-decomposable compound is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, and the acid generator is 0.5.
˜15 parts by weight, preferably 1.0 to 10 parts by weight, and an epoxy propyl compound or an epoxy compound is 0.0
It is 1 to 15 parts by weight, preferably 0.1 to 10 parts by weight. Examples of the resin used in the two-component positive-type radiation-sensitive resin composition before being imparted with acid decomposition performance include the alkali-soluble resin and polyvinyl benzoic acid resin used in the above-mentioned three-component resist. However, it is not limited to this. As a group that imparts acid decomposing ability,
t-BOC group, tert-butyl group, pyranyl group, silyl group,
Examples thereof include alkoxy groups, ester groups, acetal groups, and the like, but are not limited to these. As the acid generator, those mentioned in the three-component resist are used. The content ratio of each component of the two-component resist is 50 to 99.9 parts by weight, preferably 80 to 99 parts by weight, when the total solid content is 100 parts by weight, the acid-decomposable alkali-soluble resin. . Acid generator is 0.1-5
It is 0 part by weight, preferably 1 to 20 parts by weight. The amount of the acid generating component in the one-component resist is 1 with respect to the polymer.
˜50 mol%, preferably 2˜30 mol%, and the amount of acid-decomposable component is 50˜99 mol%, preferably 70˜80 mol%, based on the polymer.

The radiation-sensitive resin composition is usually used in the form of a resist solution by dissolving the above components in an organic solvent.
The solvent used at this time is ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol methyl ether acetate, (methoxypropyl)
Acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, methyl cellosolve, ethyl cellosolve, methyl isobutyl ketone, cyclohexanone, methyl lactate, ethylactate, butyl lactate and the like can be mentioned. These may be used alone or as a mixture.

The positive type radiation sensitive resin composition of the present invention comprises
Further, a spectral sensitizer, a plasticizer, a photochromic agent, a dye, an adhesion improver, a surfactant and the like can be added depending on the application.

Next, a method for forming a fine pattern using the composition thus obtained will be described. The total solid content of the composition of the present invention is dissolved in the solvent as described above to a concentration of 5 to 60%, preferably 10 to 40%, and the above additives are added if necessary, and then filtered. Then, insoluble matter is removed to obtain a photosensitive solution. This photosensitive solution is first applied on a substrate such as a silicon wafer or a chromium vapor deposition plate by a spinner or the like to obtain a uniform film.
After drying the coating film by baking at a temperature of 30 ° C., preferably 80 to 120 ° C., it is irradiated with radiation such as ultraviolet rays, electron beams, X-rays and the like, and further 70 to 130 ° C., preferably 80 to 120 ° C. Heating at the temperature of
Then, a fine pattern can be transferred onto the substrate by developing with an alkaline aqueous solution having an appropriate concentration.

The heat treatment after irradiation with radiation is a treatment for amplifying the sensitivity of the positive type radiation sensitive resin composition of the chemical amplification system, and is an essential process. If this processing temperature is lower than 70 ° C., practical sensitivity cannot be obtained, and if it exceeds 130 ° C., the transfer pattern becomes thin and a good pattern cannot be obtained.

The alkaline developer used in the positive-type radiation-sensitive resin composition of the present invention is an organic alkaline aqueous solution of tetramethylammonium hydroxide, triethylamine, triethanolamine, sodium hydroxide, potassium hydroxide or sodium carbonate. Although an inorganic alkaline aqueous solution such as sodium silicate can be used, it is preferable to use an organic alkaline aqueous solution in the semiconductor integrated circuit manufacturing process. For example, development is performed as follows. Substrates that have been heat-treated after irradiation with radiation are treated with these developers at 10 to 35 ° C, preferably 15 to 30 ° C.
It is possible to obtain a resist pattern by developing for 0.5 to 30 minutes, preferably for 1 to 10 minutes by a method such as immersion or spraying.

The positive-type radiation-sensitive resin composition of the present invention comprises
High sensitivity to radiation and high stability up to heat treatment after radiation irradiation. The transfer pattern obtained from this is
It does not swell and has excellent resolution, and also has excellent dry etching resistance and heat resistance.

[0024]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Synthesis Example 1 Acid-decomposable compound Synthesis of 3,3-bis (4-tert-butoxycarbonyloxy-3-methylphenyl) -phthalide 3,3-bis (4-hydroxy-3-methylphenyl)
Phthalide (common name: cresolphthalein) 5.43g
(15.7 mmol) and di-tert-butyl-dicarbonate 7.29 g (33.4 mmol) were dissolved in 50 ml of tetrahydrofuran. Then, after adding 3.75 g (47.5 mmol) of pyridine to this solution, 50 to 6
The reaction was carried out at 0 ° C for 5 hours. After the reaction, tetrahydrofuran was distilled off under reduced pressure, a small amount of methanol was added and the mixture was allowed to stand at -10 ° C overnight. The precipitated crystals were collected by filtration and washed with methanol to obtain the desired product. Yield 4.8g, melting point 126-129 ° C

Synthesis Example 2 Acid-decomposable compound Synthesis of tris (4-tert-butoxycarbonyloxyphenyl) tris (4-hydroxyphenyl) methane 5.0 g (1
7.1 mmol) and di-tert-butyl dicarbonate 1
1.5 g (52.7 mmol) of tetrahydrofuran 3
It was dissolved in 0 ml. Next, 5.3 g (52.4 mmol) of triethylamine was added to this solution, and the mixture was refluxed for 8 hours. The reaction solution was cooled to room temperature and poured into water to precipitate white crystals. This was collected by filtration, washed with water, and dried under vacuum to obtain 8.6 g of the desired product. Melting point 100-102 [deg.] C.

Synthesis Example 3 Epoxypropyl compound Synthesis of 2,3-epoxypropyl biphenyl ether 17.0 g (0.1 mol) of p-phenylphenol,
55.5 g (0.6 mol) of epichlorohydrin was dissolved in 13.9 g of dimethyl sulfoxide. Then, 4.25 g (0.105 mol) of sodium hydroxide was added to 10
After the addition in portions, the reaction temperature was raised as follows. 5
30 minutes at 0 ° C, 30 minutes at 60 ° C, 60 minutes at 70 ° C. After that, the mixture was concentrated under reduced pressure with an evaporator, and unreacted epichlorohydrin and dimethyl sulfoxide were distilled off. Then, 50 g of methyl isobutyl ketone (MIBK) was added, and 30
% Sodium hydroxide 1.33 g (0.01 mol) 7
The mixture was added at 0 ° C and stirred at the same temperature for 60 minutes. Then, the mixture was cooled and the MIBK layer was washed with water. Then, after liquid separation, concentration under reduced pressure,
MIBK was distilled off to obtain a product. Yield 23g. Then, the product was distilled under reduced pressure to obtain the target product. Melting point 90.5
~ 93.5 ° C

Example 1 74.5 parts by weight of m, p cresol novolac resin having a weight average molecular weight of 12,000 and the acid-decomposable compound 2 of Synthesis Example 1
3.8 parts by weight, 1.5 parts by weight of triphenylsulfonium-trifluoromethanesulfonate as an acid generator, and 0.15 of the epoxypropyl compound of Synthesis Example 3.
Part by weight was dissolved in ethyl lactate so that the concentration was 17.3%, and the resulting solution was pressure-filtered using a membrane filter having a pore size of 0.1 μm to obtain a photosensitive solution.

Next, the photosensitive solution thus obtained was placed on a chromium vapor-deposited substrate, the surface of which was subjected to a surface treatment by a known method, for 4, 5
A resist layer having a film thickness of 0.5 μm was obtained by spin coating at 00 rpm for 30 seconds and drying on a hot plate having a surface temperature of 100 ° C. for 3 minutes. Next, this resist layer was irradiated with various irradiation doses at an accelerating voltage of 20 KV using an ELS-3300 electron beam drawing apparatus manufactured by Elionix Co., Ltd. After irradiation, the substrate is taken out into the atmosphere, left in a room, heated at a constant temperature for 3 minutes on a hot plate having a surface temperature of 110 ° C., and then immersed in a 2.38% tetramethylammonium hydroxide aqueous solution for 60 seconds. The electron beam irradiation part was dissolved and removed to obtain a pattern.

Stability up to heating after irradiation was evaluated by observing and comparing with an electron microscope the pattern thus obtained and the pattern obtained by heating and developing under the above conditions immediately after electron beam irradiation. . In heating and development immediately after irradiation, 3 μC / cm ² is the optimum irradiation amount, and 1 μm, 0.
A 5 μm rectangular line pattern was obtained. The residual film rate was about 100%.

After irradiation for 1 hour, 2 hours, 4 hours, 8 hours, and 16 hours, heat treatment and development were performed, and the change in the pattern was observed with an electron microscope. Up to 8 hours after irradiation, 1 μm, 0.
There was almost no change in the line pattern of 5 μm. After 16 hours, thinning of the pattern was observed. The stability after irradiation was remarkably improved as compared with the comparative example described below.

Example 2 A photosensitive solution was obtained in the same manner as in Example 1 except that the weight average molecular weight of the cresol novolac resin in Example 1 was changed to 24,000 and the amount of the epoxypropyl compound was changed to 0.75 part by weight. It was The subsequent treatment was performed in the same manner as in Example 1. The optimum irradiation amount was 10 μC / cm ² in heating and development immediately after irradiation. There was almost no change in the lie pattern until 8 hours after irradiation.

Example 3 79.2 parts by weight of m, p cresol novolac resin having a weight average molecular weight of 10,000, and acid-decomposable compound 1 of Synthesis Example 2
6.8 parts by weight, 3.0 parts by weight of triphenylsulfonium trifluoromethanesulfonate as an acid generator,
As an epoxypropyl compound, 1.0 part by weight of N- (2,3-epoxypropyl) putalimide was dissolved in ethyl lactate so that the concentration of (Aldrich reagent) was 24.0%, and the resulting solution was dissolved in 0.1 μm. A photosensitive solution was obtained by pressure filtration using a membrane filter.

Then, the photosensitive solution thus obtained was spin-coated on a silicon wafer wafer at 4000 rpm for 30 seconds, and the solution was applied to a hot plate having a surface temperature of 100 ° C. for 9 seconds.
A resist layer having a film thickness of 1.0 μm was obtained by drying for 0 seconds. Then, the resist layer is irradiated with deep ultraviolet rays having a wavelength of 254 nm through a mask having a pattern drawn,
Immediately after irradiation, a pattern in heating and developing for 5 minutes on a hot plate having a surface temperature of 90 ° C. was compared with a pattern in heating and developing under the same conditions after standing for a certain time after irradiation. Grace
The development was performed for 2 minutes with a 2.38% tetramethylammonium hydroxide aqueous solution. The transferred pattern had a residual film rate of 95%, and was left to stand for 8 hours after irradiation and heated, and the development pattern was almost the same as the pattern immediately after irradiation and development.

Example 4 Polyvinylphenol having a weight average molecular weight of 6000 was reacted with ditertiary butyl dicarbonate by a conventional method to modify the hydroxyl group of polyvinylphenol by t-BOC to obtain a resin having acid decomposition performance. . Hydroxyl group t-B
OC conversion is the peak of carbonate group (1750 cm)
And the peak ratio of the hydroxyl group peak (3400 cm) in the infrared absorption spectrum. The conversion rate was 30 mol%. 87 parts by weight of the above resin, 10 parts by weight of diphenyliodonium trifluoromethanesulfonate as an acid generator, and 3 parts by weight of the compound of Synthesis Example 3 as an epoxypropyl compound were dissolved in ethyl lactate at a concentration of 20.0% to obtain a product. The solution was pressure-filtered using a 0.1 μm membrane filter to obtain a photosensitive solution. Next, the photosensitive solution thus obtained was spin-coated on a silicon wafer at 4000 rpm for 30 seconds to obtain a surface temperature of 10
A resist layer having a thickness of 1.0 μm was obtained by drying on a hot plate at 0 ° C. for 90 seconds. Then, a wavelength of 254 is applied to this resist layer through a patterned mask.
Immediately after the irradiation, the pattern was heated for 2 minutes on a hot plate having a surface temperature of 90 ° C., and the pattern in the development was compared with the pattern in the development after being left for a certain period of time after the irradiation. The development was carried out for 1 minute with a 2.38% tetramethylammonium hydroxide aqueous solution. The pattern after heating for 8 hours after irradiation and after development was almost the same as the pattern after heating and development immediately after irradiation.

Comparative Example 1 A photosensitive solution was prepared in the same manner as in Example 1 except that the epoxypropyl compound of Synthesis Example 3 was omitted. Then, the subsequent operations were performed in the same manner as in Example 1, and the stability up to the heat treatment after irradiation was evaluated. However, heat treatment immediately after irradiation,
The pattern obtained by development has a large film thickness and the residual film ratio is 6
The pattern profile was 0% and the pattern profile was not good.

Comparative Example 2 A photosensitive solution was prepared in the same manner as in Example 1, except that the epoxypropyl compound of Synthesis Example 3 was omitted. In Comparative Example 1, the film slippage was large and the stability could not be evaluated.
The temperature was changed to 3 minutes, and the stability after irradiation and before heat treatment was evaluated. In this condition, the residual film rate was about 100%.

The irradiation dose is 1 μC / cm ^{2 to} 10 μC / cm
Irradiation was performed in the range of up to ² , and changes in the resist pattern after development by heating immediately after irradiation and heating after a fixed time were observed and evaluated by an electron microscope. 1.6 in heating and developing immediately after irradiation
μC / cm ² was the optimum irradiation dose, and the same rectangular line patterns of 1 μm and 0.5 μm as in Example 1 were obtained.
At doses higher than this, the pattern had a taper, and the dimensional accuracy was greatly deviated with dose. After irradiation for 1 hour, heat treatment was performed, development was performed, and the pattern was observed. At the optimum irradiation dose of 1.6 μC / cm ^{2 above} ,
No pattern could be observed. Therefore, it can be seen that the stability remains within 1 hour even if the conditions are selected unless the present invention is applied. Even at an overirradiation dose of 10 μC / cm ² , only traces of 1 μm line patterns could be observed, and traces could not be observed at 0.5 μm line patterns.

[0039]

The positive-type radiation-sensitive resin composition of the present invention has high sensitivity to radiation and high stability up to heat treatment after irradiation with radiation, and the transfer pattern obtained from this composition does not swell. Excellent resolution, dry etching resistance and heat resistance.

Claims (2)

[Claims] 1. A chemically amplified positive-working radiation-sensitive resin composition containing an acid generator that generates an acid when exposed to radiation, wherein the composition contains an epoxypropyl group or a compound having an epoxy group. Positive radiation-sensitive resin composition characterized by 2. A transfer pattern obtained from the positive-type radiation-sensitive resin composition according to claim 1.