JP2000292924A - Radiation sensitive composition and pattern forming method, and manufacture of semiconductor apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation sensitive composition having a chemical structure transparent to ArF excimer laser beams having a wavelength of 193 nm and high in resistance to dry etching, and a method for forming a negative pattern free from swelling and high in resolution and superior in developability by using an aqueous developing solution of widely used tetramethylammonium hydroxide. SOLUTION: This radiation sensitive composition contains as the base resin of a resist a polymer having a γ-hydroxyacid structure synthesized by reducing and opening a ring of at least one part of the acid anhydride of a copolymer comprising at least 2 kinds of monomers of a nonconjugated cyclic diene of 5-methylenebicyclo[2,2,1]hepto-2-ene, and citraconic acid anhydride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive composition used in microfabrication technology in a manufacturing process of a semiconductor device and the like, a microlithography process using the same, and a method of manufacturing a semiconductor device and the like including the microlithography process. About. More specifically, a wavelength 2 of ArF excimer laser light or the like, which is a shorter wavelength light source than a high-pressure mercury lamp or a KrF excimer laser, which is a current ultraviolet light source, is used.
The present invention relates to a negative-type radiation-sensitive composition, a pattern forming method, and a semiconductor device manufacturing method suitable for a photolithography process using far ultraviolet rays of 20 nm or less, particularly a lithography process using a super-resolution technique such as a phase shift method.

[0002]

2. Description of the Related Art A photolithography technique for forming a fine pattern on the order of microns or submicrons in an electronic device such as a semiconductor has played a central role in mass production fine processing technology. The recent demand for higher integration and higher density of semiconductor devices is
Many advances have been made in microfabrication technology. In particular, as the minimum processing size approaches the exposure wavelength, photolithography technology using a KrF excimer laser (248 nm) from g-line (436 nm) and i-line (365 nm) of a high-pressure mercury lamp and a shorter wavelength light source is developed. It has been. In response to these changes in the exposure wavelength, materials corresponding to the respective wavelengths of the photoresist have been developed.

Conventionally, photoresists suitable for these wavelengths have different sensitizers or photosensitive mechanisms. However, aqueous alkali development using the aqueous alkali solubility of a resin or polymer material having a phenol structure is industrially required. Has been used. These resins or polymer materials inevitably contain a large amount of aromatic rings, which was also a chemical structural element for improving the etching resistance in a dry etching step after the formation of a resist pattern.

A negative resist using such a resin having a phenol structure is disclosed in JP-A-62-1640.
45 and a dissolution inhibiting type as disclosed in JP-A-4-165359. In any case, a submicron fine pattern can be formed without swelling.

In recent years, ArF has been used as a photolithography in a region where the minimum processing size is smaller than 0.25 μm.
Expectations for photolithography using an excimer laser (193 nm) as a light source are increasing. However, this wavelength is the absorption maximum due to the aromatic ring, and in a photoresist material having a phenol structure as a main component which has been conventionally used industrially, an exposure latent image can be formed only on the very surface of the photoresist film, It was difficult to form a fine resist pattern by aqueous alkali development.

On the other hand, various resist materials having high transmittance in this wavelength region and high dry etching resistance have been proposed. ArF excimer laser wavelength 19
As a chemical structure which is transparent in a far ultraviolet region including 3 nm and can impart dry etching resistance to a resist material, use of an adamantane skeleton in place of an aromatic ring is disclosed in Japanese Patent Application Laid-Open No. 4-3966.
5, Japanese Patent Application Laid-Open No. 5-265212, and Japanese Patent Application Laid-Open Nos. 5-80515 and 5-2572 similarly disclose the use of a norbornane skeleton.
84. In addition to these structures, it is disclosed in JP-A-7-28237 and JP-A-8-259626 that general alicyclic structures such as a tricyclodecanyl group are effective.

As for a resist material which is made of a polymer having a chemical structure transparent in a far ultraviolet region including a wavelength of 193 nm of an ArF excimer laser and which can be developed with aqueous alkali,
As disclosed in JP-A-4-39665, JP-A-4-184345, JP-A-4-226461, JP-A-5-80515, etc., attempts have been made to utilize a carboxylic acid structure of acrylic acid or methacrylic acid. . In these, the aqueous alkali solubility of the portion dissolved in the developer in aqueous alkali development depends on the carboxylic acid structure of acrylic acid or methacrylic acid. Also, JP-A-8-259
No. 626 discloses a polymer compound in which a carboxylic acid group is added to an alicyclic structure introduced into a methacrylic ester side chain.

In the phenol structure conventionally used as an alkali-soluble group, pKa = 10.0 (phenol), whereas in these carboxylic acid structures, pKa is
The value is low at Ka = 4.8 (acetic acid) and the acidity is high. Therefore, when they are used as the alkali-soluble groups of the base resin, the resin having a carboxylic acid structure generally has a higher dissolution rate in an aqueous alkali at the same mole fraction, and has a lower dissolution rate than the resin having a phenol structure. The resin having a carboxylic acid structure dissolves even in an alkaline developer having a high concentration.

When a resin having a carboxylic acid as described above is used, if a crosslinking agent as disclosed in JP-A-62-164045 is used, a carboxylic acid having a high acidity remains in a crosslinked portion. There was a drawback that the alkali developer infiltrated there and swelled to form a fine pattern. In addition, when a compound having a dissolution inhibiting action is formed by an acid generated upon exposure as disclosed in JP-A-4-165359, a resin having a carboxylic acid does not provide a dissolution contrast and does not produce a negative resist. There was a disadvantage.

On the other hand, a method for forming a non-swelling negative pattern using a resin having a carboxylic acid structure is disclosed in Japanese Patent Application No. 9-210360.
-Hydroxy acid structures are known which utilize the fact that they are converted into γ-lactone or δ-lactone structures by an acid-catalyzed reaction.

[0011]

Problems to be Solved by the Invention Japanese Patent Application No. 9-21036
In the method for forming a pattern using a resin having a γ- or δ-hydroxy acid structure, the resin used therein is a non-conjugated resin such as 5-methylenebicyclo [2.2.1] hept-2-ene. It is synthesized by radical copolymerization of a cyclic diene and maleic anhydride, reducing the maleic anhydride portion to lactone, and hydrolyzing and modifying it. However, because of its high hydrophilicity, this resin is 2.38% by weight, a standard developer used in microlithography processes using conventional g-line, i-line and KrF excimer laser resists. The tetramethylammonium hydroxide aqueous solution has a disadvantage that the developer concentration is too high and high resolution cannot be obtained.

A first object of the present invention is to use the esterification reaction of .gamma.-hydroxycarboxylic acid and to use 2.38% by weight of tetramethylammonium hydroxide which is a general-purpose standard developer without swelling. An object of the present invention is to provide a negative-type radiation-sensitive composition having excellent resolution performance capable of developing a fine pattern.

A second object of the present invention is to provide a method for forming a negative pattern using such a radiation-sensitive composition. Further, a third object of the present invention is to provide a method for manufacturing a semiconductor device using such a pattern forming method.

[0014]

In order to achieve the first object, the radiation-sensitive composition of the present invention comprises a copolymer comprising at least two kinds of monomers, a non-conjugated cyclic diene and a citraconic anhydride. At least a part of the acid anhydride portion of the above (1), which contains at least a polymer having a γ-hydroxy acid structure synthesized by reducing and opening a ring, and an acid generator.

Citraconic anhydride has a structure in which one hydrogen atom in the double bond of maleic anhydride is substituted with a methyl group. Therefore, the copolymer formed from citraconic anhydride is hydrophobic in structure by the amount of the methyl group. This increases the solubility of the polymer having a γ-hydroxy acid structure derived from the copolymer,
This is considered to be the reason for making it suitable for a 2.38% by weight aqueous solution of tetramethylammonium hydroxide.

The resin as described above can be obtained by subjecting a non-conjugated cyclic diene and citraconic anhydride to a radical copolymer, reducing the anhydride portion to form a lactone, and hydrolyzing and modifying the lactone. . The weight average molecular weight of these resins is desirably 1,000 to 300,000.

As the non-conjugated cyclic diene, 5-methylenebicyclo [2.2.1] hept-2-ene, cycloocta-1,5-diene, 5-ethylenebicyclo [2.
2.1] Hept-2-ene, 5-vinylbicyclo [2.
2.1] hept-2-ene and the like, but are not limited thereto.

A γ-hydroxy acid structure synthesized by reducing and ring-opening at least a part of an acid anhydride portion of a copolymer comprising at least two kinds of monomers of a non-conjugated cyclic diene and a citraconic anhydride is used. The acid generator is preferably used in an amount of 0.1 to 50 parts by weight, more preferably 0.5 to 2 parts by weight, based on the weight of the polymer.
The range is 0 parts by weight.

Examples of the acid generator include onium salts such as triphenylsulfonium triflate, dimethylphenylsulfonium triflate, dimethyl-4-hydroxynaphthyl triflate, N-trifluoromethanesulfonyloxynaphthylimide, and N-methanesulfonyloxynaphthylimide. , N-trifluoromethanesulfonyloxysuccinimide, sulfonyloxyimides such as N-perfluorooctanesulfonyloxysuccinimide, and furthermore, sulfonic acid esters and the like, and active actinic radiation such as ArF excimer laser irradiation. What is necessary is just to generate | occur | produce an acid, and it is not limited to these. Further, two or more of these acid generators may be used at the same time.

Further, the radiation-sensitive composition of the present invention has a composition for improving resolution, process stability and storage stability.
Basic compounds such as 2-benzylpyridine, tripentylamine and triethanolamine, and salts such as tetramethylammonium iodide and tetrapentylammonium chloride may be added. It is desirable to add 0.01 to 100 parts by weight of these basic compounds and salts to the acid generator used.

Further, the radiation-sensitive composition of the present invention may contain a compound having an alicyclic structure for improving dry etching resistance and transmittance. Examples of the alicyclic structure include adamantyl, norbornane, tricyclodecane and androstane structures. These structures are transparent in the deep ultraviolet region and have dry etching resistance.

In order to achieve the second object, the pattern forming method of the present invention comprises a step of forming a coating film comprising any of the above-described radiation-sensitive compositions on a substrate, A step of irradiating the pattern with active actinic radiation, a step of heating the substrate after irradiation with actinic radiation, and a step of exposing the coating film to an aqueous alkali solution after heating the substrate to remove the unirradiated portions of the actinic radiation. It is.

The actinic radiation used in the present invention has a wavelength of 250.
Far ultraviolet light of nm or less, particularly vacuum ultraviolet light such as ArF excimer laser light. Note that an electron beam, EUV, X-ray, or the like can also be used.

In the present invention, when irradiating a predetermined pattern of actinic radiation, vacuum ultraviolet light such as ArF excimer laser light is formed into a predetermined pattern through a usual mask or reticle. In this case, it is more preferable that the mask be a phase shift mask since a pattern with high resolution can be obtained. As the phase shift mask, there are a Levenson type, an outrigger type, a halftone type, a shifter edge type, and the like, but any phase shift mask may be used.

The aqueous alkaline developer used in the present invention is preferably an aqueous solution of a tetraalkylammonium hydroxide having 1 to 5 carbon atoms. Also suitable is a general-purpose 2.38% by weight aqueous solution of tetramethylammonium hydroxide that has been used for developing i-line and g-line resists and KrF excimer laser resists.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a resist pattern on a semiconductor substrate by any one of the above-described pattern forming methods; Process of etching
Alternatively, the method includes a step of implanting ions into the substrate.

Examples of the etching method used in the semiconductor manufacturing method of the present invention include dry etching methods such as plasma etching, reactive ion etching, and reactive ion beam etching, and wet etching methods.

The substrate to be processed in the semiconductor device manufacturing method of the present invention is an oxide film such as a silicon dioxide film or a coating glass film formed by a CVD method or a thermal oxidation method, or a nitride film such as a silicon nitride film. Is mentioned. In addition, various metal films such as aluminum and its alloys, tungsten, and polycrystalline silicon can be used.

[0029] Since elements formed by the method of manufacturing a semiconductor device of the present invention, particularly memory elements, can be formed with a fine pattern, the degree of integration can be increased. Therefore, since the elements can be made small, the number of elements that can be obtained from one wafer increases, and the yield improves.

In the present invention, by utilizing lactonization having high reactivity among esterification of carboxylic acids, conversion of carboxylic acid to carboxylic acid ester can be efficiently performed by a catalytic reaction using an acid generated by exposure. Can be. Since this reaction is intramolecular esterification, cross-linking between molecules does not occur, and the amount of the carboxylic acid simply changes between the exposed portion and the unexposed portion. If the carboxylic acid and the alcohol are separate molecules, only a few percent of the carboxylic acid is esterified in the membrane by the acid-catalyzed reaction under practically applicable conditions. On the other hand, in the reaction for converting γ-hydroxy acid into γ-lactone used in the pattern forming method of the present invention,
In the exposed part, 30% or more of the carboxylic acid can be esterified. Further, the produced ester is not hydrolyzed by a commonly used aqueous solution of tetraalkylammonium hydroxide and is stable during development. Therefore, the dissolution rate greatly changes, and since no cross-linking reaction occurs, swelling can be avoided and a fine pattern can be formed.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. First, prior to the examples, synthetic examples of the materials used in the present invention will be described.

<Synthesis Example 1> Synthesis of polymer (1b) having γ-hydroxy acid structure In a 500 ml three-necked flask equipped with a thermometer, a cooling tube and a nitrogen inlet tube, 5-methylenebicyclo [2.2] .
1] 26.4 g of hept-2-ene, 25.2 g of citraconic anhydride, 4.1 g of 2,2′-azobis (isobutyronitrile), 300 g of tetrahydrofuran, and 70 ° C. while introducing nitrogen , And the polymerization was carried out for 8 hours. After the polymerization, the solution was poured into 1000 ml of n-hexane to precipitate the polymer, which was dried to obtain 19.4 g of 5
-Methylenebicyclo [2.2.1] hept-2-ene-
A citraconic anhydride copolymer (1a) was obtained (yield 38).
%).

The structure of the obtained polymer was found to be mainly the structure of Chemical Formula 1 from various analytical methods. Here, in the formula, n represents an integer. In addition, when the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography (GPC), the weight average molecular weight was 2,200 and the number average molecular weight was 1,600.

[0034]

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A 500 ml three-necked flask was charged with 3.0 g of sodium borohydride and 100 g of tetrahydrofuran, cooled to 0 ° C. in an ice bath, and stirred under nitrogen to synthesize 5-methylenebicyclo [2] as described above. .
2.1] A solution of 17.4 g of hept-2-ene-citraconic anhydride copolymer in 120 g of tetrahydrofuran was added dropwise over about 1 hour. Stir for several hours after dropping,
Left overnight.

After the solution was poured into about 300 ml of water and stirred, about 1N aqueous hydrochloric acid was gradually added to the solution to make it weakly acidic at about pH 4. About 200 ml of ethyl acetate
Was added and extraction was performed twice, and the obtained organic layer was added to 150 ml.
Of water three times. After washing, the organic layer was dried over anhydrous sodium sulfate, and after drying, the solvent was removed by distillation under reduced pressure.
The mixture was poured into 800 ml of hexane, and the precipitated polymer was dried to obtain 13.8 g of a white powdery polymer.

According to various analytical methods, the structure of the obtained polymer was determined to be a structure in which the anhydride portion of (1a) was reduced to form a lactone, and a compound having at least a ring-opened γ-hydroxy acid structure. The polymer of Formula 3 (1
b). Where l and m
Represents an integer.

[0038]

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[0039]

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100 parts by weight of the obtained polymer (1b) was dissolved in 600 parts by weight of diacetone alcohol to obtain a polymer having a pore size of 0.
Filtered with a 2 μm filter. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a polymer film. When the coating film (410 nm in thickness) was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 2.38% by weight), the interference color changed and dissolved in 8.2 seconds.
The remaining film became zero. In addition, when the solubility was examined using a dissolution rate monitor, it was found that they were sequentially dissolved from the surface without swelling. In addition, the diluted tetramethylammonium hydroxide aqueous solution (concentration: 0.113% by weight)
When immersed, no dissolution occurred.

The absorption spectrum of the film obtained by coating the above-mentioned polymer solution on a lithium fluoride substrate was measured by a vacuum ultraviolet spectroscope (manufactured by ARC). The absorbance at 193 nm was 0.80 at a film thickness of 1.0 μm. Yes, it was found that the absorption was small.

<Synthesis Example 2> Synthesis of polymer (2b) having γ-hydroxy acid structure 5-methylenebicyclo [2.2.1] used in Synthesis Example 1
Instead of hept-2-ene, cycloocta-1,5-
Radical polymerization was carried out in the same manner as in Synthesis Example 1 using 24.3 g of diene to obtain 16.3 g of cycloocta-1,5-diene-citraconic anhydride copolymer (2a) (yield 3).
3%). The structure of the obtained polymer was found to be mainly the structure of Chemical Formula 4 from various analytical methods. Where n
Represents an integer. As for the molecular weight of this polymer in terms of polystyrene, the weight average molecular weight was 1,700 and the number average molecular weight was 1,200.

[0043]

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When the anhydrous portion was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1,
The structure of the obtained polymer was determined from various analytical methods (2a)
Was found to be a polymer (2b) of formula (5) or (6) having at least a structure in which the anhydride portion was reduced and lactonized, and at least a ring-opened γ-hydroxy acid structure. Here, l and m represent an integer.

[0045]

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[0046]

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<Synthesis Example 3> Synthesis of Polymer (3b) Having γ-Hydroxy Acid Structure 5-Methylenebicyclo [2.2.1] used in Synthesis Example 1
Radical polymerization was carried out in the same manner as in Synthesis Example 1 except that 27.0 g of 5-ethylenebicyclo [2.2.1] hept-2-ene was used instead of hept-2-ene, and 16.0 g of 5-
Ethylenebicyclo [2.2.1] hept-2-ene-citraconic anhydride copolymer (3a) was obtained (yield: 30).
%). The structure of the obtained polymer was found to be mainly the structure of Chemical Formula 7 from various analytical methods. Here, n represents an integer. The molecular weight of this polymer in terms of polystyrene was 2,200 as the weight average molecular weight and 1,700 as the number average molecular weight.

[0048]

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The anhydrous portion was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1.
The structure of the obtained polymer was determined by various analytical methods (3a)
Was found to be a polymer (3b) of Formula 8 or 9 having at least a structure in which the anhydride portion was reduced and lactonized, and at least a ring-opened γ-hydroxy acid structure. Here, l and m represent an integer.

[0050]

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[0051]

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<Synthesis Example 4> Synthesis of polymer (4b) having γ-hydroxy acid structure 5-methylenebicyclo [2.2.1] used in Synthesis Example 1
Radical polymerization was carried out in the same manner as in Synthesis Example 1 using 27.0 g of 5-vinylbicyclo [2.2.1] hept-2-ene instead of hept-2-ene, and 17.1 g of 5-
Vinyl bicyclo [2.2.1] hept-2-ene-citraconic anhydride copolymer (4a) was obtained (yield: 32).
%). The structure of the obtained polymer was found to be mainly the structure of Chemical Formula 10 from various analytical methods. Where n
Represents an integer. The polystyrene-equivalent molecular weight of this polymer was 2,000 in weight average molecular weight and 1,500 in number average molecular weight.

[0053]

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The anhydride was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1.
The structure of the obtained polymer was determined by various analytical methods (4a)
Was found to be a polymer (4b) of formula (11) or formula (12) having at least a structure in which the anhydride portion was reduced and lactonized, and at least a ring-opened γ-hydroxy acid structure. Here, l and m represent an integer.

[0055]

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[0056]

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Example 1 100 parts by weight of the polymer (1b) having a γ-hydroxy acid structure synthesized in Synthesis Example 1
3 parts by weight of an acid generator, triphenylsulfonium triflate, was dissolved in 600 parts by weight of diacetone alcohol, and filtered using a Teflon (registered trademark) filter having a pore size of 0.20 μm to obtain a resist solution.

The resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.30 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 43%.

ArF excimer laser stepper (NA =
0.60), the resist film was exposed through a Levenson-type phase shift mask. After exposure, 1
A post-exposure bake was performed at 00 ° C. for 2 minutes. Then 23 ° C
Of tetramethylammonium hydroxide aqueous solution (2.
(38% by weight), the unexposed portion of the film dissolved in 10 seconds. Therefore, development was carried out for 40 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds.
As a result, when the exposure amount was 62 mJ / cm ² ,
A μm line and space pattern was obtained. On this occasion,
No swelling of the pattern was observed. Also, when the obtained substrate with the pattern was immersed in tetrahydrofuran,
The pattern dissolved instantaneously, indicating that no crosslinking had occurred.

Further, regarding the above resist film, CHF
Etching was performed using a parallel plate type reactive ion etching apparatus using _three gases. The conditions were a CHF ₃ flow rate of 35 sccm, a gas pressure of 10 mTorr, and an RF bias power of 150 W. As a result, the etch rate of this resist was 1.21 in comparison with a commercially available novolak resin of 1.0, and it was found that the resist had sufficiently high dry etching resistance without practical problems. In addition, when the resist film was coated and heated at 160 ° C. for 2 minutes instead of 100 ° C., the etch rate ratio was 1.15, and it was found that the dry etching resistance was further increased.

The above resist applied on the NaCl plate is
ArF excimer light was irradiated at 62 mJ / cm ² , and infrared absorption spectra before and after baking after exposure were measured.
As a result, it was found that the peak at 3300 cm ^-1 due to the carboxylic acid and the hydroxyl group was significantly reduced after the post-exposure bake. It was also found that the peak at 1735 cm ^-1 of carboxylic acid decreased and the peak at 1780 cm ^-1 caused by lactone increased. From the intensity of these absorptions, about 70% of the carboxylic acid that was
Was found to be lactonized after exposure.

The resist film initially had the structure of the polymer (1b) having a γ-hydroxy acid structure, and was alkali-soluble by the carboxylic acid. ArF excimer laser exposure generated trifluoromethanesulfonic acid from the acid generator triphenylsulfonium triflate. During the post-exposure bake, using the acid as a catalyst, the γ-
The structure of the hydroxy acid is esterified by intramolecular dehydration, and γ
Resulting in the structure of the lactone. As a result, the exposed portion was 2.3
It became insoluble in 8% by weight of an alkali developing solution, and a negative pattern was formed. The mechanism of the negative conversion at this time was not a crosslinking reaction but a large decrease in the amount of carboxylic acid due to lactonization, so that a fine pattern could be formed without swelling.

Example 2 Instead of the polymer (1b) having a γ-hydroxy acid structure used in Example 1, 100 parts by weight of the polymer (2b) synthesized in Synthesis Example 2 was used, and an acid generator trifluoromethanesulfonyl was used. 2 parts by weight of oxynaphthylimide was dissolved in 600 parts by weight of diacetone alcohol, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution.

On a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, the above-mentioned resist solution was spin-coated, and after coating, heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.33 μm. Formed. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 60%.

Exposure was performed through a chromium mask using an ArF excimer laser stepper in the same manner as in Example 1, followed by baking after exposure at 100 ° C. for 2 minutes. An aqueous solution of tetramethylammonium hydroxide at 2.degree.
(% By weight), the unexposed portion of the film was dissolved in 8 seconds. Therefore, development takes 3 times as long as 4 times
This was performed for 2 seconds, and then rinsed with pure water for 60 seconds. As a result, a negative 0.18 μm line and space pattern was obtained at an exposure dose of 70 mJ / cm ² . At this time, no swelling of the pattern was observed.

Further, with respect to the above resist film, Example 1
Etching was performed under the following conditions. As a result, the etch rate of this resist was 1.30 when the etching rate of a coating film of a commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.

Example 3 100 parts by weight of the polymer (1b) having a γ-hydroxy acid structure used in Example 1
Acid generator dimethylphenylsulfonium triflate 3
Parts by weight, 0.15 parts by weight of 2-benzylpyridine was dissolved in 600 parts by weight of diacetone alcohol, and the pore size was 0.20 μm.
The solution was filtered using a Teflon filter of m to obtain a resist solution.

On a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, the above-mentioned resist solution was spin-coated, followed by heating at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.33 μm. Was formed. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 50%.

Exposure was performed using an ArF excimer laser stepper through a Levenson-type phase shift mask in the same manner as in Example 1, followed by baking after exposure at 90 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (2.38% by weight) at 23 ° C., the unexposed portion of the film dissolved in 8 seconds. Therefore, the development was performed for 32 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds. As a result, a negative 0.125 μm line and space pattern was obtained at an exposure amount of 85 mJ / cm ² . At this time, no swelling of the pattern was observed.

Example 4 In place of the polymer (1b) having a γ-hydroxy acid structure used in Example 1, 100 parts by weight of the polymer (3b) having a γ-hydroxy acid structure synthesized in Synthesis Example 3 was used. Then, 5 parts by weight of an acid generator, diphenyliodonium triflate, and 0.25 parts by weight of tetramethylammonium iodide were dissolved in 400 parts by weight of diacetone alcohol, and filtered using a Teflon filter having a pore diameter of 0.20 μm to obtain a resist solution.

The resist solution described above was spin-coated on a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, and then heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.55 μm. Was formed.

This was exposed to a line and space pattern using an electron beam lithography apparatus with an acceleration voltage of 50 kV. After exposure baking at 100 ° C for 2 minutes,
Of tetramethylammonium hydroxide aqueous solution (2.
(38% by weight), the unexposed portion of the film dissolved in 15 seconds. Therefore, development was performed for 60 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds.
As a result, at an exposure amount of 10 μC / cm ² , a negative 0.18
A μm line and space pattern was obtained. On this occasion,
No swelling of the pattern was observed.

Further, with respect to the above resist film, Example 1
Etching was performed under the following conditions. As a result, the etch rate of this resist was 1.33 when the etching rate of the coating film of a commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.

<Example 5> Instead of the polymer (1b) having a γ-hydroxy acid structure used in Example 1, 100 parts by weight of the polymer (4b) having a γ-hydroxy acid structure synthesized in Synthesis Example 4 was used. Then, 5 parts by weight of an acid generator, camphorsulfonyloxynaphthylimide, was dissolved in 500 parts by weight of diacetone alcohol, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution.

The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, and then heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.52 μm. Was formed.

The resist film was exposed through a Levenson-type phase shift mask using a KrF excimer laser stepper (NA = 0.45). After baking at 90 ° C. for 2 minutes after exposure, the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (2.38% by weight) at 23 ° C., and the unexposed portion of the film dissolved in 12 seconds. Therefore, the development was performed for 48 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds. As a result, a negative 0.18 μm line and space pattern was obtained at an exposure amount of 20 mJ / cm ² . At this time, no swelling of the pattern was observed.

Further, with respect to the above resist film, Example 1
Etching was performed under the following conditions. As a result, the etch rate of this resist was 1.35 when the etching rate of a coating film of a commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.

<Embodiment 6> FIG. 1 shows a well-known MOS (metal-
1 shows a cross-sectional view of an (oxide-semiconductor) transistor. In the figure, 12 is a field oxide film, 13 is a source contact, 14 is a drain contact, 15 is polycrystalline silicon, 16 is a source electrode, 17 is a drain electrode, 18 is a gate electrode, and 19 is a protective film. The transistor is
The voltage applied to the gate electrode 18 causes the source electrode 16
And the drain current flowing between the drain electrodes 17 is controlled.

Here, the steps for fabricating such a structure consist of dozens of steps. These steps can be roughly divided into three steps: a step up to the formation of a field oxide film, a step up to the formation of a gate, and a final step. Can be divided. Here, the process up to the first field oxide film formation (FIG. 2) includes a process of forming a resist pattern on the silicon nitride film. This field oxide film was formed as in the following examples.

According to a known method, as shown in FIG.
A 50 nm oxide film 22 is formed on a mold silicon wafer 21, and a 200 nm silicon nitride film 23 is formed thereon by plasma CVD to form a substrate. A resist pattern 24 having a 0.30 μm line is formed on the substrate by using the material and the method described in the second embodiment (FIG. 2B). After the silicon nitride film 23 is etched by a known method using the resist pattern as a mask (FIG. 2C), boron ions for channel stopper are implanted using the resist pattern 24 as a mask again. After removing the resist (FIG. 2D), a 1.2 μm field oxide film 25 is formed in the element isolation region by selective oxidation using the silicon nitride film 23 as a mask (FIG. 2E).

Thereafter, a gate forming step and a final step were performed according to a known method. After etching the silicon nitride film, the gate is oxidized and polycrystalline silicon 26 is grown (FIG. 2F). A resist pattern 27 having a 0.12 μm line is formed on the substrate by using the pattern forming method described in the first embodiment (FIG. 2G). Using this resist pattern 27 as a mask, polycrystalline silicon 2 is formed by a known method.
6 is formed to form a gate 28 (FIG. 2).
(H)).

Although not shown below, the thin oxide film of the source and drain is etched, arsenic is diffused in the polycrystalline silicon gate and the source and drain, and an oxide film is formed in the polycrystalline silicon gate and the source and drain regions. Form. Open contacts for aluminum wiring to the gate, source, and drain, perform aluminum coating and patterning, further form a protective film, and open pads for bonding. Thus, a MOS transistor as shown in FIG. 1 is formed.

Here, regarding the MOS transistor,
In particular, a method for forming a field oxide film has been described. However, it is needless to say that the present invention is not limited to this, but can be applied to other semiconductor device manufacturing methods and processes.

Example 7 A semiconductor memory device was manufactured by using the pattern forming method shown in Examples 1 to 3 of the present invention. FIG. 3 is a cross-sectional view showing main steps of manufacturing the device.

As shown in FIG. 3A, a P-type Si semiconductor 31 is used as a substrate, and an element isolation region 32 is formed on the surface thereof by using a known element isolation technique. Next, for example, thickness 1
A word line 33 having a structure in which 50 nm of polycrystalline Si and 200 nm of SiO ₂ are laminated is formed, and further, for example, 150 nm of SiO ₂ is deposited using a chemical vapor deposition method, and is processed anisotropically. Side spacers 3 of SiO ₂ on side walls of word lines
4 is formed. Next, the n diffusion layer 35 is formed by a usual method. Next, as shown in FIG. 3B, a data line 36 made of polycrystalline Si, a refractory metal silicide, or a laminated film of these is formed through a normal process.

Next, as shown in FIG. 3C, a storage electrode 38 made of polycrystalline Si is formed through a normal process. Then, Ta ₂ O ₅ , Si ₃ N ₄ , SiO ₂ , BST, PZ
T, ferroelectric, or a composite film of these,
The capacitor insulating film 39 is formed. Continue with polycrystalline S
i, refractory metal, refractory metal silicide, or A
A plate electrode 40 is formed by applying a low-resistance conductor such as l or Cu.

Next, as shown in FIG. 3D, a wiring 41 is formed through a normal process. Next, a memory element was manufactured through a normal wiring forming step and a passivation step. Note that, here, only typical manufacturing steps have been described, but other than this, ordinary manufacturing steps were used. Further, the present invention can be applied even if the order of each step is changed.

In the lithography process in the device manufacturing process, the pattern forming materials and the methods described in the first to third embodiments of the present invention are applied to almost all processes. The present invention is not necessarily applied to a process in which the size of the pattern is large. For example, the present invention was not applied to a conductive hole forming step in a passivation step or a pattern formation in an ion implantation mask forming step.

Next, a pattern formed by lithography will be described. FIG. 4 shows a typical pattern arrangement of a memory unit constituting a manufactured memory element. 42 is a word line,
43 is a data line, 44 is an active area, 45 is a storage electrode, and 46 is a pattern of an electrode extraction hole. Also in this example, the pattern forming materials and the methods of Examples 1 to 3 of the present invention were used for all except the formation of the electrode extraction hole 46 shown here. In addition to the pattern formation shown here, the present invention was used in the process using the minimum design rule.

In the device manufactured by using the present invention, the size between the patterns could be reduced as compared with the device manufactured by using the conventional method. Therefore, the device having the same structure could be reduced. The number of wafers that can be manufactured from one wafer has increased, and the yield has improved.

Comparative Example 1 Synthesis of Polymer (5b) Having γ-Hydroxy Acid Structure Polymerization was performed using maleic anhydride instead of citraconic anhydride used in Synthesis Example 1. 21.2 g of 5-methylenebicyclo [2.2.1] hept-2-ene and 19.6 g of maleic anhydride were polymerized with 2.56 g of 2,2′-azobis (isobutyronitrile) to obtain 37.5 g. Of 5
-Methylenebicyclo [2.2.1] hept-2-ene-
A maleic anhydride copolymer (5a) was obtained (yield 92).
%). The structure of the obtained polymer was found to be mainly the structure of Chemical Formula 13 from various analytical methods.

Here, in the formula, n represents an integer. Further, when the molecular weight of this polymer in terms of polystyrene was examined, the weight average molecular weight was 5,800 and the number average molecular weight was 2,
500.

[0093]

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When the anhydride portion was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1, the structure of the obtained polymer was determined by various analytical methods according to (5).
It was found that the anhydride portion of a) was a reduced lactonized structure and that it was a polymer (5b) of Formula 14 or Formula 15 having at least a ring-opened γ-hydroxy acid structure. Here, in the formula, l and m represent integers.

[0095]

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[0096]

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100 parts by weight of the obtained polymer (5b) was dissolved in 600 parts by weight of diacetone alcohol to obtain a polymer having a pore size of 0.
Filtered with a 2 μm filter. Spin it on, 10
Baking was performed at 0 ° C. for 2 minutes to obtain a polymer film.

The film (film thickness 470) applied on the silicon substrate
nm) was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.113% by weight). The solution melted in 6.2 seconds while the interference color changed, and the residual film became zero. Next, when the film was immersed in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide, the film was instantaneously dissolved, and the dissolution rate could not be measured.

100 parts by weight of the polymer (5b) and 3 parts by weight of an acid generator, triphenylsulfonium triflate, were dissolved in 600 parts by weight of diacetone alcohol.
The solution was filtered using a 20 μm Teflon filter to obtain a resist solution. The above resist solution is spin-coated on the silicon substrate treated with hexamethyldisilazane,
Heat treatment was performed at 0 ° C. for 2 minutes to form a resist film having a thickness of 0.40 μm.

In the same manner as in Example 1, the resist film was exposed through an ArF excimer laser stepper (NA = 0.60) through a mask. After exposure, a post-exposure bake was performed at 90 ° C. for 2 minutes. Subsequently, the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C.
Dissolved in 2 seconds. Therefore, development takes 48 times as long as that time.
Rinsing with pure water for 60 seconds. As a result, a negative 0.17 μm line and space pattern was obtained at an exposure dose of 24 mJ / cm ² . At this time, no swelling of the pattern was observed.

Next, the resist film exposed and baked after the exposure under the above conditions was developed with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide, and the unexposed portion of the film was instantaneously dissolved. Development was performed for 10 seconds, followed by rinsing with pure water for 60 seconds. As a result, the exposure amount is 30 m
At J / cm ² , a negative 0.30 μm line and space pattern was obtained, but a pattern smaller than that could not be resolved.

[0102]

According to the present invention, 2.38% by weight of general-purpose
By developing with a tetramethylammonium hydroxide aqueous solution, a high-resolution pattern could be formed without swelling the fine pattern. ArF with high dry etching resistance
A negative radiation-sensitive composition suitable for excimer laser lithography, a pattern forming method using the same, and a method for manufacturing a semiconductor device using the same were provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a MOS (metal-oxide-semiconductor) transistor.

FIG. 2 is a cross-sectional view showing a method for forming a field oxide film and a silicon gate using the pattern forming method of the present invention.

FIG. 3 is a cross-sectional view illustrating a process of a method of manufacturing a semiconductor memory device using the pattern forming method of the present invention.

FIG. 4 is a plan view showing a typical pattern arrangement of a memory unit constituting a memory element.

[Explanation of symbols]

12 ... field oxide film, 13 ... source contact, 1
4 ... Drain contact, 15 ... Polycrystalline silicon, 16
... source electrode, 17 ... drain electrode, 18 ... gate electrode, 19 ... protective film, 22 ... oxide film, 23 ... silicon nitride film, 24 ... resist pattern, 25 ... field oxide film,
26 ... polycrystalline silicon film, 27 ... resist pattern, 28
... polycrystalline silicon gate, 31 ... P-type Si semiconductor substrate,
32 element isolation regions, 33, 42 word lines, 34 side spacers, 35 n diffusion layers, 36, 43 data lines 38, 45 storage electrodes, 39 insulating films for capacitors, 40 plate electrodes, 41: wiring, 44: active area, 46: electrode extraction hole.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 236/20 C08F 236/20 5F046 C08K 5/36 C08K 5/36 C08L 45/00 C08L 45/00 47 / 00 47/00 G03F 7/20 502 G03F 7/20 502 521 521 7/32 7/32 7/38 501 7/38 501 H01L 21/027 H01L 21/30 502R 569E (72) Inventor Yoshiyuki Yokoyama Yoshiyuki Kokubunji, Tokyo 1-280 Higashi Koigakubo, Hitachi, Ltd., Central Research Laboratory, Hitachi, Ltd. (72) Inventor Hiroaki Oizumi 1-280 Higashi Koikekubo, Kokubunji, Tokyo, Japan No. 280 F-term in Hitachi Central Research Laboratory, Ltd. (Reference) 2H025 AA02 AA04 AA09 AB 16 AC04 AC08 AD01 BE00 BE10 CB11 CB41 CB43 CB45 FA12 FA17 FA39 FA41 2H096 AA25 BA06 EA03 EA05 FA01 GA09 HA11 HA30 2H097 CA13 CA17 FA02 HB03 JA02 JA03 LA10 4J002 BH021 BK001 BL021 EV236 EV246 EV296 FD206 GP03 BA03 4 HB25 HB63 JA38 5F046 BA08 CA04 CB17 JA04 JA22 LA12

Claims (9)

[Claims] 1. A γ-hydroxy acid synthesized by reducing and ring-opening at least a part of an acid anhydride portion of a copolymer comprising at least two kinds of monomers, a non-conjugated cyclic diene and a citraconic anhydride. A radiation-sensitive composition comprising at least a polymer having a structure and an acid generator. 2. The radiation-sensitive composition according to claim 1, wherein the non-conjugated cyclic diene is 5-methylenebicyclo [2.2.1] hept-2-ene. . 3. The radiation-sensitive composition according to claim 1, wherein the acid generator is used in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the polymer having a γ-hydroxy acid structure. A radiation-sensitive composition, comprising: 4. A step of forming a coating film comprising the radiation-sensitive composition according to claim 1 on a substrate, a step of irradiating the coating film with an actinic ray of a predetermined pattern, A method for forming a negative-type pattern, comprising: a step of heating a substrate after irradiation with radiation; and exposing the coating film to an aqueous alkali solution after heating the substrate to remove a non-irradiated portion of active radiation. 5. The pattern forming method according to claim 4, wherein said active actinic ray is far ultraviolet light having a wavelength of 250 nm or less. 6. The pattern forming method according to claim 4, wherein said active actinic ray is ArF excimer laser light. 7. The pattern forming method according to claim 4, wherein the active actinic radiation of the predetermined pattern is ArF excimer laser light through a phase shift mask. . 8. The pattern forming method according to claim 4, wherein said alkaline aqueous solution is a tetraalkylammonium hydroxide aqueous solution. 9. A step of forming a resist pattern on a semiconductor substrate by the pattern forming method according to claim 4, a step of etching the semiconductor substrate based on the resist pattern, or a step of ion etching. A method of manufacturing a semiconductor device, comprising: