JP3394014B2 - Alkali-soluble resin for photoresist - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkali-soluble resin used in photoresists suitable for deep ultraviolet (including excimer laser) exposure lithography.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of integrated circuits has increased, submicron pattern formation has been required. In particular, excimer laser lithography uses 64M and 256M DR
It is attracting attention because it makes it possible to manufacture AM. And with the change to such a laser light source,
In addition to the conventional properties such as heat resistance, residual film rate, and profile, the resist is required to have the following new properties. A) High sensitivity to the above light source. B) High resolution.

In view of such circumstances, so-called chemically amplified resists utilizing an acid catalyst and a chemical amplification effect have been proposed. The mechanism of action of this resist is to change the solubility of the exposed portion and the non-exposed portion in an alkali developing solution by a reaction using an acid generated from a photo-acid generator by light irradiation as a catalyst. The chemically amplified resist provides a positive or negative resist pattern by such a mechanism.

Polyvinylphenol has been often used as a resin for a chemically amplified resist. However, since polyvinylphenol has too high solubility in an alkali developing solution, a resist using it has a problem that sensitivity and resolution are insufficient.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive research mainly on polyvinylphenol resins used for chemically amplified resists, and as a result, have excellent performance by using a specific resin. It was found that a photoresist composition can be obtained, and the present invention has been completed. An object of the present invention therefore, heat resistance, residual film ratio, coating properties, while maintaining various performances profiles such as an alkali-soluble resin which can be a negative full photoresists compositions sensitivity and excellent chemical amplification type in resolution To provide.

[0006]

That is, according to the present invention, poly (p-vinylphenol) in which 10 to 35 mol% of hydroxyl groups are alkyl etherified or 5 to 30 mol% of hydroxyl groups is used.
Is an alkyl etherified hydrogenated polyvinyl phenol, and has a polystyrene-reduced weight average molecular weight in the range of 1,500 to 8,000 as determined by gel permeation chromatography (GPC) method. The present invention provides an alkali-soluble resin for negative photoresists (excluding tert-butyl etherified resins).

The partially alkyletherified polyvinylphenol is poly (p-vinylphenol), and the ratio of the alkyletherified portion of its hydroxyl groups (alkyletherification rate) is 10 to 10.
35 mol%, and more preferably, the alkyl etherification rate is 15 to 22 mol%. The partially alkyletherified hydrogenated polyvinylphenol has an alkyletherification rate of 5 to 30 mol%. In particular, the alkyl etherification rate is more preferably 8 to 20 mol%. When applying these alkali-soluble resins to the photoresist composition, it is of course possible to use both in combination. When used in combination, the mixing ratio of both is appropriately set.

The alkyl ether in these alkali-soluble resins may be linear or branched, but has 1 carbon atom.
The thing of -4 is preferable. Particularly preferred are methyl ether and ethyl ether.

Partially alkyletherified polyvinylphenols include, for example, polyvinylphenol and alkyl halides described by GN Vyas et al., Org.
It can be produced by a method of reacting according to the description of sesColl. Vol. IV, 836 (1963) and the like. The partially alkyletherified hydrogenated polyvinylphenol can be produced, for example, by a method of reacting hydrogenated polyvinylphenol and an alkyl halide according to the description of GN Vyas et al. Hydrogenated polyvinylphenol can be produced by hydrogenating polyvinylphenol according to a conventional method.

The alkali-soluble resin has a polystyrene-reduced weight average molecular weight in the range of 1,500 to 8,000 as determined by the gel permeation chromatography (GPC) method.

In applying the partially alkyletherified polyvinylphenol and / or the partially alkyletherified hydrogenated polyvinylphenol according to the present invention to a photoresist composition, together with one or both of these, Alkali-soluble resins other than those may be used in combination. Other alkali-soluble resin that can be used in combination, for example, vinylphenol resin,
Isopropenylphenol resin, copolymer of vinylphenol and styrene (ratio of vinylphenol in the copolymer is preferably 50 mol% or more), copolymer of isopropenylphenol and styrene (isophenol in the copolymer) The proportion of propenylphenol is preferably 50 mol% or more), partially t-butoxycarbonyloxylated polyvinylphenol, hydrogenated polyvinylphenol and the like. These other alkali-soluble resins,
It is used in an appropriate mixing ratio with respect to the partially alkyletherified polyvinylphenol and / or the partially alkyletherified hydrogenated polyvinylphenol as long as the effect of the present invention is not impaired.

The above alkali-soluble resin is combined with an acid generator and an acid functional compound selected from a crosslinking agent and a dissolution inhibitor to form a photoresist composition. In the case of using a crosslinking agent as the acid functional compound act on negative.

As the acid generator, sulfonic acid ester of N-hydroxyimide compound is preferably used. Specific examples of the sulfonic acid ester include compounds represented by the following general formula (I).

[0014]

[Chemical 1]

In the formula, R ¹ represents an optionally substituted arylene, alkylene or alkenylene group, and R ² represents an optionally substituted alkyl or aryl group.

In the general formula (I), the arylene group represented by R ¹ may be monocyclic or bicyclic, and specific arylene groups include phenylene and naphthylene. Suitable substituents for the arylene group include a halogen atom, a nitro group, an acetylamino group and the like. Similarly, the alkylene group may be linear or branched, and preferably has 1 to 6 carbon atoms. Particularly preferred alkylene groups are ethylene, propylene and the like. Suitable substituents on the alkylene group include:
Examples thereof include a halogen atom, a lower alkoxy group and a monocyclic aryl group. Similarly, the alkenylene group may be, for example, one having 2 to 6 carbon atoms, preferably vinylene and the like. Suitable substituents for the alkenylene group include monocyclic aryl groups and the like.

In the general formula (I), the alkyl group represented by R ² may be linear, branched or cyclic, but is preferably linear or branched C1-8.
The following are listed. Examples of suitable substituents on the alkyl group include a lower alkoxy group and the like. Similarly, the aryl group may be monocyclic or bicyclic, but monocyclic ones are preferable.

Among the sulfonates represented by the general formula (I), the compounds represented by the following general formula (II) can be mentioned as preferable ones.

[0019]

[Chemical 2]

In the formula, R ¹ has the same meaning as described above and R ^{2 '}
Represents an optionally substituted alkyl or aryl group, but when R ^{2 ′} is an alkyl or aryl group having a substituent, the substituent is not fluorine.

The sulfonic acid ester represented by the general formula (I) can be prepared, for example, by GF Jaubert, Ber. Dtsch. Chem.,
28, 360 (1895), DE Ames et al., J. Chem. Soc., 35.
18 (1955), MA Stolberg et al., J. Amer. Chem. So.
c., 79, 2615 (1957), etc. according to the following general formula (III)

[0022]

[Chemical 3]

(Wherein R ¹ has the same meaning as described above)
A cyclic N-hydroxyimide compound represented by
This is described, for example, by L. Bauer et al., J. Org. Chem., 24, 129.
According to the method described in 3 (1959), by reacting with a sulfonic acid chloride corresponding to R ² —SO ₂ Cl (wherein R ² has the same meaning as described above) under basic conditions,
It can be manufactured.

The sulfonic acid ester of the N-hydroxyimide compound corresponding to the general formula (I) or (II) can be used alone or in combination of two or more kinds. Specific examples of the sulfonic acid ester of the N-hydroxyimide compound suitable for use in combination with the alkali-soluble resin according to the present invention include the following compounds.

[0025]

[Chemical 4]

Examples of the cross-linking agent used in the negative photoresist composition include, for example, Japanese Patent Application No. 4-15009 (Japanese Patent Application Laid-Open No.
The compound having a methylol group or a methylol ether group described in JP-A 5-210239). Such a cross-linking agent having a methylol group or a methylol ether group can be used alone or in combination of two or more kinds. Examples of suitable cross-linking agents include the following compounds.

[0027]

[Chemical 5]

A preferable composition ratio in the negative photoresist composition containing a crosslinking agent is 50 to 95% by weight of an alkali-soluble resin, 1 to 20% by weight of a photoacid generator, and 1 to 30% by weight of a crosslinking agent. Is . At the negative photoresist composition, if necessary, a sensitizer may be incorporated dyes, various additives which are conventional in the art, such as adhesion improving agent.

The photoresist solution is usually the negative type described above.
Each solid content of the full photoresists composition, so that the total concentration of 10 to 50% by weight, is prepared by mixing in a solvent. Examples of the solvent used here include ethyl cellosolve acetate, methyl cellosolve acetate,
Ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethyl lactate, butyl acetate, ethyl pyruvate, 2-
Examples include heptanone, cyclohexanone, methyl isobutyl ketone, xylene and the like. These solvents may be used alone or in admixture of two or more.

[0030]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, all parts are by weight unless otherwise specified.

Example 1 10.0 g of polyvinylphenol (Maruka Linker M manufactured by Maruzen Petrochemical Co., Ltd .; weight average molecular weight 4,150) was dissolved in acetone, and then 12.0 g of potassium carbonate and 3.3 of ethyl iodide.
8 g was added and heated under reflux for 6 hours. The reaction mixture was poured into a mixed solution of 600 ml of water and 350 ml of ethyl acetate, acidified by adding hydrochloric acid, and then shaken and extracted. The organic layer was washed with water until the washing liquid became neutral, and then the solvent was distilled off under reduced pressure. The residue was dissolved in 25 ml of methanol and then poured into 1.3 liter of water. The precipitate was filtered and dried to obtain polyvinylphenol in which 18.8% of hydroxyl groups were ethyl etherified.

Examples 2 to 4 In the same manner as in Example 1 except that the amounts of ethyl iodide used were changed to 3.84 g, 3.90 g and 2.96 g, respectively, the ethyl etherification rate was 20.3%. , 21.8% and 16.7% of partially ethyl etherified polyvinylphenol were obtained.

Evaluation Example 1 13.5 parts of partially ethyl etherified polyvinyl phenol having an ethyl etherification rate of 18.8% obtained in Example 1, 1.0 part of hexamethylol melamine hexamethyl ether as a cross-linking agent and a photo-acid generator. As a solution, 1.0 part of methanesulfonic acid ester of N-hydroxysuccinimide was dissolved in 48 parts of diethylene glycol dimethyl ether.
This solution was filtered through a Teflon filter having a pore size of 0.1 μm to prepare a resist solution.

This resist solution was applied to a silicon wafer cleaned by a conventional method to a thickness of 0.7 μm using a spin coater. Then, this silicon wafer was prebaked on a hot plate at 100 ° C. for 1 minute. A KrF excimer laser stepper (manufactured by Nikon, NSR-1755 EX8A, NA = 0.4) having an exposure wavelength of 248 nm is passed through a chromium mask having a pattern on the coating film after prebaking.
5) was used for exposure. After the exposure, this wafer was heated on a hot plate at 100 ° C. for 1 minute to crosslink the exposed portion. This was developed with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide to obtain a negative pattern. As a result of observing the formed pattern with an electron microscope, a fine pattern of 0.25 μm was resolved with a good profile at an exposure dose of 42 mJ / cm ² .
No scum was observed on the wafer from which the resist layer was removed in the non-exposed area.

Evaluation Example 2 A negative type pattern was obtained in the same manner as in Evaluation Example 1 except that the partially ethyl etherified polyvinyl phenol obtained in Example 2 and having an ethyl etherification rate of 20.3% was used as the alkali-soluble resin. . As a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.25 μm was resolved with an exposure dose of 25 mJ / cm ² .

Evaluation Example 3 A negative pattern was obtained in the same manner as in Evaluation Example 1 except that the partially ethyl etherified polyvinylphenol having an ethyl etherification rate of 21.8% obtained in Example 3 was used as the alkali-soluble resin. . As a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.25 μm was resolved with an exposure dose of 20 mJ / cm ² .

Evaluation Example 4 A negative pattern was obtained in the same manner as in Evaluation Example 1 except that the partially ethyl etherified polyvinyl phenol having an ethyl etherification rate of 16.7% obtained in Example 4 was used as the alkali-soluble resin. . As a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.25 μm was resolved with an exposure dose of 29 mJ / cm ² .

Evaluation Example 5 As an alkali-soluble resin, 8.1 parts of partially ethyl etherified polyvinylphenol having an ethyl etherification rate of 20.3% obtained in Example 2 and a molar ratio of vinylphenol and styrene of 70:30 were used. Copolymer (Maruka Linker CST-70 manufactured by Maruzen Petrochemical Co., Ltd .; weight average molecular weight 1,720) 5.4
A negative pattern was obtained in the same manner as in Evaluation Example 1 except that the mixture of parts was used. As a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.25 μm was resolved with an exposure dose of 27 mJ / cm ² .

Comparative Example 1 Polyvinylphenol as an alkali-soluble resin 13.
A resist solution was prepared in the same manner as in Evaluation Example 1 except that 5 parts was used. This resist solution was applied to a silicon wafer cleaned by a conventional method to a thickness of 0.7 μm using a spin coater. Then, the silicon wafer was prebaked in an oven at 100 ° C. for 1 minute. The prebaked coating film was exposed through the patterned chrome mask using the same KrF excimer laser stepper used in Evaluation Example 1. After the exposure, this wafer was heated on a hot plate at 105 ° C. for 1 minute to crosslink the exposed portion. This was developed with a 2.0% by weight aqueous solution of tetramethylammonium hydroxide to obtain a negative pattern. As a result of observing the formed pattern with an electron microscope, only a 0.35 μm pattern could be resolved at an exposure dose of 50 mJ / cm ² .

Example 5 Hydrogenated polyvinylphenol (Marukalinker PHM-C manufactured by Maruzen Petrochemical Co .; weight average molecular weight 5,400) 10.0
After dissolving g in acetone, 12.0 g of potassium carbonate and 1.95 g of ethyl iodide were added, and the mixture was heated under reflux for 6 hours. After filtering the reaction mixture, the filtrate was poured into 2,000 ml of pH 3 acetic acid aqueous solution, and the precipitated resin was collected by filtration and dried. The dried resin was dissolved in acetone to a concentration of 20% by weight, the acetone solution and hexane were mixed at a weight ratio of 2: 1, and the mixture was further stirred at room temperature for 1 hour and then left to stand. Acetone layer is collected and deionized water is 2,000 m
The mixture was poured into 1 l, and the precipitated resin was collected by filtration and dried to obtain hydrogenated polyvinylphenol in which 15% of hydroxyl groups were ethyl etherified.

Example 6 Example 5 except that the amount of ethyl iodide was changed to 1.56 g.
In the same manner as above, a partially ethyl etherified hydrogenated polyvinyl phenol having an ethyl etherification rate of 12% was obtained.

Evaluation Example 6 13.5 parts of partially ethyl etherified hydrogenated polyvinylphenol having an ethyl etherification rate of 15% obtained in Example 5
1.0 part of hexamethylol melamine hexamethyl ether as a cross-linking agent and 1.0 part of methanesulfonic acid ester of N-hydroxysuccinimide as a photo-acid generator,
It was dissolved in 48 parts of diethylene glycol dimethyl ether. This solution was filtered through a Teflon filter having a pore size of 0.1 μm to prepare a resist solution.

This resist solution was applied to a silicon wafer washed by a conventional method to a thickness of 0.7 μm using a spin coater. Then, this silicon wafer was prebaked on a hot plate at 100 ° C. for 1 minute. The prebaked coating film was exposed through the patterned chrome mask using the same KrF excimer laser stepper used in Evaluation Example 1. After the exposure, this wafer was heated on a hot plate at 100 ° C. for 1 minute to crosslink the exposed portion. This was developed with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide to obtain a negative pattern. As a result of observing the formed pattern with an electron microscope, it was found to be 0.2 with an exposure amount of 25 mJ / cm ^2.
A 5 μm fine pattern was resolved with a good profile, and no scum was observed on the wafer from which the resist layer was removed in the unexposed area.

Evaluation Example 7 6.75 parts of partially ethyl etherified hydrogenated polyvinyl phenol having an ethyl etherification rate of 15% obtained in Example 5
6.75 parts of partially ethyl etherified polyvinylphenol having an ethyl etherification rate of 22%, 1.0 part of hexamethylol melamine hexamethyl ether as a cross-linking agent, and 0.75 part of ethanesulfonic acid ester of N-hydroxysuccinimide as a photo-acid generator. Was dissolved in 60 parts of propylene glycol monomethyl ether acetate. Thereafter, a negative pattern was obtained in the same manner as in Evaluation Example 6 except that the heating temperature of the exposed wafer was changed to 110 ° C. As a result of observing the formed pattern with an electron microscope, 13 mJ
A fine pattern of 0.25 μm was resolved with a good profile with an exposure amount of / cm ² , and no scum was observed on the wafer from which the resist layer was removed in the non-exposed area.

Evaluation Example 8 10.8 parts of partially ethyl etherified hydrogenated polyvinyl phenol having an ethyl etherification rate of 12% obtained in Example 6
2.7 parts of partially ethyl etherified polyvinylphenol having an ethyl etherification rate of 22%, 1.0 part of hexamethylol melamine hexamethyl ether as a cross-linking agent, and 0.75 part of ethanesulfonic acid ester of N-hydroxysuccinimide as a photo-acid generator. Was dissolved in 60 parts of propylene glycol monomethyl ether acetate. After that,
A negative pattern was obtained in the same manner as in Evaluation Example 7. As a result of observing the formed pattern with an electron microscope, 20 mJ / cm ²
A fine pattern of 0.25 μm was resolved with a good profile at the exposure amount of 1., and scum was not observed on the wafer from which the resist layer was removed in the non-exposed area.

The above results for the negative photoresist are summarized in Table 1. In the table, "PV" in the column of resin
"P" is an abbreviation for polyvinyl phenol.

[0047]

[Table 1]

[0048]

Industrial Applicability The alkali-soluble resin according to the present invention, which is polyvinylphenol or hydrogenated polyvinylphenol, in which a part of the hydroxyl groups is alkyl etherified, has the following properties when applied to a photoresist composition:
Not only is it excellent in various properties such as heat resistance, residual film rate, coating property, and profile, but it also exhibits high sensitivity and high resolution in the exposure region using a deep ultraviolet (including excimer laser) light source. Therefore, in lithography using the above-mentioned light source, the resolution and contrast can be remarkably improved, and a highly precise fine photoresist pattern can be formed.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuji Ueda 3-98 Kasugade, Konohana-ku, Osaka City Sumitomo Chemical Co., Ltd. (72) Inventor Hiromi Oka 3-chome, Kasugade, Konohana-ku, Osaka No. 98 Sumitomo Chemical Co., Ltd. (56) Reference JP-A-4-215662 (JP, A) JP-A-3-107160 (JP, A) JP-A-4-291259 (JP, A) JP-A 4-217251 (JP, A) JP-A-3-206458 (JP, A) JP-A-61-166544 (JP, A) JP-A-5-281730 (JP, A) JP-A-5-204157 (JP, A) A) Japanese Patent Laid-Open No. 6-83055 (JP, A) Japanese Patent Laid-Open No. 5-313371 (JP, A) Japanese Patent Laid-Open No. 5-507563 (JP, A) International Publication 92/8166 (WO, A1) (58) Field (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (2)

(57) [Claims] 1. A gel permeate comprising poly (p-vinylphenol) in which 10 to 35 mol% of hydroxyl groups are alkyl etherified or hydrogenated polyvinyl phenol in which 5 to 30 mol% of hydroxyl groups are alkyl etherified. The polystyrene-reduced weight-average molecular weight determined by solution chromatography (GPC) is in the range of 1,500 to 8,000. Negative photoresist alkali-soluble resin (provided that it is tert-butyl etherified). Excluding things.). 2. The alkali-soluble resin for a negative photoresist according to claim 1, wherein the alkyl in the alkyl ether has 1 to 4 carbon atoms.