JP2002090998A - Radiation-sensitive composition, pattern forming method and method for producing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative type radiation-sensitive composition developable with an aqueous alkali developing solution without swelling a fine pattern and excellent also in shelf stability and to provide a pattern forming method using the composition and a method for producing a semiconductor device using the composition. SOLUTION: The radiation-sensitive composition is obtained by incorporating water into a radiation sensitive composition containing at least a resin having a γ- or δ-hydroxycarboxylic acid structure and a compound which generates an acid when irradiated with active radiation.

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 for a fine processing technique in a manufacturing process of a semiconductor device and the like, and a microlithography process using the same.
And a method for manufacturing a semiconductor device or the like including the microlithography process. 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 KrF excimer laser which is a current ultraviolet light source.
The present invention relates to a negative-type radiation-sensitive composition suitable for a photolithography process using far ultraviolet rays of 20 nm or less, a pattern forming method, and a semiconductor device manufacturing 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 photosensitizers or photosensitive mechanisms, but aqueous alkali development utilizing the aqueous alkali solubility of a resin or a polymer material having a phenol structure has been industrially used. Was. 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, expectations have been growing for photolithography using an ArF excimer laser (193 nm) as a light source as a photolithography in a region where the minimum processing dimension is smaller than 0.25 μm. However, this wavelength is the absorption maximum due to the aromatic ring, and in the conventional industrially used photoresist material having a phenol structure as a main component, an exposure latent image can be formed only on the extreme 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
The use of an adamantane skeleton as a chemical structure that is transparent in the far ultraviolet region including 3 nm and can impart dry etching resistance to a resist material instead of an aromatic ring is disclosed in Japanese Patent Laid-Open No. 4-396.
65, JP-A-5-265212, and JP-A-5-80515 and JP-A-5-257.
284. In addition to these structures,
It is disclosed in JP-A-7-28237 and JP-A-8-259626 that general alicyclic structures such as tricyclodecanyl groups are effective.
Is disclosed.

A polymer having a transparent chemical structure in a far ultraviolet region including a wavelength of 193 nm of an ArF excimer laser,
With respect to the resist material which has been made aqueous alkali developable, JP-A-4-39665, JP-A-4-184345,
As disclosed in JP-A-4-226461 and JP-A-5-80515, attempts have been made to utilize the 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-8-2
59626 discloses a polymer compound in which a carboxylic acid group is added to an alicyclic structure introduced into a methacrylic acid ester side chain.

In a 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 problem that the alkali developing solution infiltrated there and swelled and a fine pattern could not be formed. 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 problem.

On the other hand, as a method for forming a non-swelling negative pattern by using a resin having a carboxylic acid structure, a γ- or δ-hydroxycarboxylic acid structure is converted into γ-lactone or γ-lactone by an acid-catalyzed reaction. Japanese Patent Application Laid-Open No. H11-109627 discloses a technique utilizing the change to a δ-lactone structure.
Seen in

[0010]

In a γ-hydroxycarboxylic acid structure or a δ-hydroxycarboxylic acid structure,
Efficient esterification in the molecule by an acid catalyst to form a lactone having a 5- or 6-membered ring structure.
As a result, the number of carboxylic acids is greatly reduced. Therefore, unlike the cross-linking reaction in which the reaction occurs between molecules and the number of carboxylic acids hardly changes between the exposed and unexposed parts, the penetration of the developer hardly occurs in the exposed and insolubilized parts, which is a problem of the prior art. There is no swelling of the pattern after development which was a point.

However, γ-hydroxy acids or δ
The -hydroxy acid structure has a problem that storage stability is low because, in a solution, intramolecular esterification gradually progresses and changes into a γ-lactone or δ-lactone structure.

A first object of the present invention is to provide a negative radiation-sensitive composition which can be developed with an aqueous alkaline developer without swelling of a fine pattern and has excellent storage stability. A second object is to provide a negative pattern forming method using such a radiation-sensitive composition.
A third object is to provide a method for manufacturing a semiconductor device using such a pattern forming method.

[0013]

In order to achieve the first object, the photosensitive composition of the present invention comprises a resin having a γ-hydroxycarboxylic acid structure or a δ-hydroxycarboxylic acid structure, and an actinic radiation. The radiation-sensitive composition containing at least a compound capable of generating an acid upon irradiation further contains water.

Γ-hydroxycarboxylic acid structure or δ
The hydroxycarboxylic acid structure causes an intramolecular esterification reaction using an acid generated from a compound which generates an acid upon irradiation with actinic radiation as a catalyst to generate a 5- or 6-membered lactone. The water generated at the same time volatilizes out of the system by heating. This reaction is an intramolecular esterification reaction,
Esterification proceeds easily and the number of carboxylic acids is greatly reduced. Therefore, unlike the cross-linking reaction in which the reaction occurs between the molecules and the amount of the carboxylic acid hardly changes between the exposed part and the unexposed part, the developer hardly penetrates into the exposed and insoluble part. As a result, it is possible to provide a photosensitive composition having no pattern swelling after development, which is a problem of the prior art.

When a γ-hydroxy acid or δ-hydroxy acid structure is made into a solution, it gradually causes an intramolecular esterification reaction to generate a γ-lactone or δ-lactone structure, and further produces water as a by-product. The intramolecular esterification reaction in this solution proceeds until a chemical equilibrium between the γ-hydroxy acid or δ-hydroxy acid, the γ-lactone or δ-lactone structure, and water is reached. Therefore, in the solution that has been adjusted and stored for a while, the amount of γ-hydroxy acid or δ-hydroxy acid is reduced as compared to when the solution was adjusted. As a result, there has been a problem that the solubility of the coating film in the aqueous alkaline developer cannot be sufficiently obtained, or a residue remains between patterns after development, and as a result, the resolution is reduced.

The reduction of the hydroxy acid structure by this intramolecular esterification reaction and the production of lactone and water are in a chemical equilibrium relationship. In the present invention, it is possible to bring the chemical equilibrium state closer to the hydroxy acid structure side by adding a large amount of water when preparing the solution. As a result, intramolecular esterification of a γ-hydroxy acid or a δ-hydroxy acid in a solution can be suppressed, and a photosensitive composition having excellent storage stability can be provided.

Further, by adding water, the polarity of the solution can be increased. As a result, the hydroxy acid structure in the solution can be stabilized, and storage stability can be improved.

The water used in the radiation-sensitive composition of the present invention is 5 to 50 parts by weight based on 100 parts by weight of the resin.
It is desirable to contain 0 parts by weight. More preferably, 5
Desirably, the content is 0 to 200 parts by weight. 5
If the amount is less than 10 parts by weight, sufficient storage stability may not be improved, and if it exceeds 500 parts by weight, the resin may not be dissolved in a solvent.

The photosensitive composition of the present invention is used by dissolving it in a solvent and spin-coating it as a solution on a substrate. At this time, any solvent may be used as long as the above components are sufficiently dissolved and a solvent capable of forming a uniform coating film by spin coating, but the higher the polarity in the solution, the more stable the hydroxy acid structure. It is desirable to use a more polar solvent. Moreover, you may use individually or in mixture of 2 or more types.

The γ-hydroxycarboxylic acid structure or δ-hydroxycarboxylic acid structure used in the photosensitive composition of the present invention is preferably a chemical structure represented by the following formula (1) or (2). .

[0021]

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[0022]

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Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ ,
R ⁷ and R ⁸ represent hydrogen or an alkyl group having 1 to 10 carbon atoms, and these alkyl groups may be connected to each other to form a cyclic alkyl group. Where R ¹ and R ³ ,
Or when R ³ and R ⁵ , or R ⁵ and R ⁷ , form a cyclic alkyl group, structurally form a 5- or 6-membered ring of γ-lactone or δ-lactone. It is more desirable because it is easy.

The carboxylic acid structure represented by the above formula (1) or (2) is desirably contained in a film forming component constituting the photosensitive composition. The film-forming component generally includes a high molecular compound having a weight average molecular weight of about 1,000 to 300,000.
An oligomer or a low molecular compound capable of forming a film may be used as long as it can be applied with a solvent. The number of the carboxylic acid structure contained in the film-forming component may be at least the amount at which the film-forming component becomes soluble in the developer used.

Here, when the carboxylic acid structure represented by the formula (1) or (2) is contained in the polymer compound and is directly contained in the main chain, it is sterically represented by the formula (1) or (2). In some cases, the carboxylic acid portion and the hydroxy group portion may be far from each other, and the lactonization reaction may not easily occur.
On the other hand, when the carboxylic acid structure represented by the formula (1) or (2) is contained in the side chain, the carboxylic acid portion and the hydroxyl group portion are hardly distant from each other in a steric manner. This is more desirable because it easily occurs and a pattern can be formed with high sensitivity.

The above-mentioned film-forming component or the photosensitive composition containing the same preferably further contains an alicyclic structure. Examples of the alicyclic structure include adamantyl, norbornane, tricyclodecane and androstane structures. These structures have high dry etching resistance,
Since it is transparent in the wavelength region of far ultraviolet light, particularly ArF excimer laser light, by including such a structure, dry etching resistance can be improved without reducing transmittance.

Examples of the compound capable of generating an acid upon irradiation with actinic radiation include onium salts such as triphenylsulfonium triflate, dimethylphenylsulfonium triflate and dimethyl-4-hydroxynaphthyl triflate, and N-trifluoromethanesulfonyloxynaphthyl. Imides, N-methanesulfonyloxynaphthylimide, N-trifluoromethanesulfonyloxysuccinimide, N-perfluorooctanesulfonyloxysuccinimide and other sulfonyloxyimides, and further include sulfonic acid esters; For example, A
It is sufficient that an acid is generated by irradiation with an rF excimer laser or the like, and the invention is not limited thereto. Further, two or more of these acid generators may be used simultaneously.

The acid generator is preferably used in an amount of 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the resin. .

Further, the photosensitive composition of the present invention contains 2-, for improving resolution, process stability and storage stability.
A basic compound such as benzylpyridine, phenylpyridine, tripentylamine, or triethanolamine, or a salt such as tetramethylammonium iodide, tetrapentylammonium chloride, or tetraethylphosphonium iodide 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.

The photosensitive composition of the present invention contains hexamethoxymethylmelamine, 1,3,4,6-tetrakis as a crosslinking agent in order to enhance the heat resistance of the formed pattern.
(Methoxymethyl) glucoururil, 1,4-dioxane-2,3-diol and the like can be contained. These crosslinking agents are desirably used in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the film forming component of the photosensitive composition.

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 one of the above-described radiation-sensitive compositions on a predetermined substrate;
Heating the substrate, irradiating the coating film with a predetermined pattern of actinic radiation, heating the substrate after irradiation with the actinic radiation, exposing the coating film to an aqueous alkali solution after heating the substrate, and not irradiating the coating with actinic radiation. The method includes a step of removing a part.

The γ- or δ-hydroxycarboxylic acid structure is changed to a γ-lactone or δ-lactone structure by an acid-catalyzed reaction, so that those soluble in an aqueous alkali developer become insoluble. As a result, a negative pattern is formed by development with an aqueous alkali. The generated γ-lactone or δ-lactone structure is not hydrolyzed by a commonly used aqueous solution of tetraalkylammonium hydroxide and is stable during development. The acid for causing the acid-catalyzed reaction is realized by using an acid generator that generates an acid upon irradiation with actinic radiation.

In the pattern forming method of the present invention, after the step of forming a coating film composed of the above-described radiation-sensitive composition on a predetermined substrate, before the step of irradiating the coating film with actinic radiation of a predetermined pattern, Preferably, the method further includes a step of heating the coating film to reduce the content of water in the coating film. The water in the coating film is volatilized by the step of heating the coating film, and the content of water is reduced, so that the γ-lactone or δ-lactone structure and water are formed from the γ-hydroxy acid or δ-hydroxy acid. The resulting intramolecular esterification reaction proceeds more efficiently.

The actinic radiation used in the present invention has a wavelength of 250 n.
m or less, and 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 usually formed into a predetermined pattern through a mask or a reticle. At this time, it is desirable to use a super-resolution technique typified by a modified illumination method or a phase shift mask because a pattern with higher resolution can be obtained.

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 are general-purpose 2.38% tetramethylammonium hydroxide aqueous solutions used in the development of i-line and g-line resists and KrF excimer laser resists, and those appropriately diluted.

The pattern forming method of the present invention desirably includes a step of heating the coating film after the step of irradiating with actinic radiation and before the step of developing with an aqueous alkaline developer. By the step of heating the coating film, the intramolecular esterification reaction for producing lactone proceeds more efficiently.

In order to achieve the third object, a method of manufacturing a semiconductor device according to the present invention comprises forming a resist pattern on a semiconductor substrate by any one of the pattern forming methods described above, and The process of etching the substrate,
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, reactive ion etching, and reactive ion beam etching, and wet etching methods. .

The substrate to be processed in the method for manufacturing a semiconductor device of the present invention is an oxide film such as a silicon dioxide film or a coatable 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.

An element, particularly a memory element, manufactured by the method for manufacturing a semiconductor device of the present invention can form a fine pattern, so that 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.
Also, the bit cost can be reduced. Therefore, a flash memory, which is a nonvolatile semiconductor memory device, or a DRAM
(Dynamic random access memory).

[0042]

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 (3b) 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] was added. Hept-2-ene 26.4 g, citraconic anhydride 25.2
g, 2,2'-Azobis (isobutyronitrile) 4.1
g and 300 g of tetrahydrofuran, and the mixture was refluxed at 70 ° C. while introducing nitrogen to carry out polymerization for 8 hours. After the polymerization, the solution was poured into 1000 ml of n-hexane, and the polymer was precipitated and dried, followed by drying with 5-methylenebicyclo [2.2.
1] 19.4 g of hept-2-ene-citraconic anhydride copolymer (3a) was obtained (yield 38%). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0044]

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In the formula, n represents an integer.

Further, when the molecular weight of this polymer in tetrahydrofuran was determined by gel permeation chromatography (GPC), the weight average molecular weight was 2,200, and the number average molecular weight was 1,600.
Met.

In a 500 ml three-necked flask were placed 3.0 g of sodium borohydride and 100 g of tetrahydrofuran, and the mixture was cooled to 0 ° C. in an ice bath under nitrogen and stirred, and 5-methylenebicyclo [2.
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. After the dropwise addition, the mixture was stirred for several hours and 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 precipitate was poured into 800 ml of n-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 (3a) was reduced to a lactone and a polymer (3b) having at least a ring-opened γ-hydroxy acid structure. ).

[0050]

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Or

[0052]

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In the formula, l and m represent integers.

<Synthesis Example 2> Synthesis of polymer (4d) having δ-hydroxy acid structure 5.0 g of androsterone and 1.5 g of pyridine were dissolved in 200 ml of tetrahydrofuran, and 1.6 g of acrylic acid chloride was added to 30 ml of tetrahydrofuran. The dissolved solution was added dropwise at 0 ° C. After the dropwise addition, the mixture was further stirred at room temperature for several hours, and the precipitated hydrochloride of pyridine was separated by filtration. 150 ml of ethyl acetate was added to the filtrate, and the mixture was washed four times with 100 ml of water. After washing with water, the organic layer was dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue crystallized. This was recrystallized from a mixed solvent of ethanol / tetrahydrofuran to obtain a white compound (4a).

[0055]

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4.0 g of the obtained monomer (4a)
Was dissolved in 40 ml of THF, and 2, 2 ′ was used as a reaction initiator.
0.19 g of azobis (isobutyronitrile) was added,
The mixture was refluxed by heating at 70 ° C. and polymerized for 6 hours. After polymerization,
The solution was poured into 500 ml of n-hexane to precipitate a polymer and dried to obtain a polymer (4b) of the monomer (4a).

[0057]

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In the formula, n represents an integer.

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 2,800 and the number average molecular weight was 2,300.

The polymer (4b) synthesized as described above
3.0 g was dissolved in 100 ml of tetrahydrofuran, and 100 ml of acetic acid and 50 ml of hydrogen peroxide were added thereto.
Stirred at 0 ° C. for several hours. After the reaction, the solvent was removed by distillation under reduced pressure, and the mixture was poured into 500 ml of water. The precipitate was separated by filtration and dried to obtain a polymer (4c) having a δ-lactone structure.

[0061]

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In the formula, n represents an integer.

The polymer (4c) synthesized as described above
2.5 g is dissolved in 100 ml of tetrahydrofuran,
Add 150 ml of 0.2N sodium hydroxide aqueous solution and add 1
Stirred for hours. An aqueous solution of hydrochloric acid was gradually added thereto to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution and extraction was performed twice, and the obtained organic layer was washed twice with 100 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate.
The mixture was poured into 00 ml, and the polymer was precipitated and dried to obtain 2.3 g of a white powdery polymer (4d). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0064]

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In the formula, l and m represent integers.

Example 1 100 parts by weight of the polymer (3b) having a γ-hydroxy acid structure synthesized in Synthesis Example 1,
3 parts by weight of the acid generator triphenylsulfonium nonaflate and 0.01 part by weight of 2-benzylpyridine were dissolved in 600 parts by weight of diacetone alcohol, and 20 parts by weight of water were further added. This was filtered using a Teflon (registered trademark) filter having a pore size of 0.20 μm to obtain a resist solution.

On a silicon substrate treated with hexamethyldisilazane, the above-mentioned resist solution was spin-coated, followed by heating at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.35 μm. This resist film was exposed through an Levenson-type phase shift mask using an ArF excimer laser stepper (ISI Microstep, NA = 0.60). After exposure, baking was performed at 100 ° 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 9 seconds. Therefore, the development was performed for 18 seconds, twice as long, and then rinsed with pure water for 15 seconds. As a result, the exposure amount 30
At mJ / cm ² , a negative 0.12 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed. When the obtained substrate with the pattern was immersed in tetrahydrofuran, the pattern was instantaneously dissolved, and it was found that no cross-linking had occurred.

Further, this resist solution was placed in a refrigerator (6 ° C.).
After storage for 7 days, little change was observed in sensitivity and resolution for 7 days, indicating that storage stability was good.

Example 2 100 parts by weight of the polymer (3b) having a γ-hydroxy acid structure synthesized in Synthesis Example 1
3 parts by weight of an acid generator triphenylsulfonium nonaflate and 0.01 parts by weight of 2-benzylpyridine were dissolved in 600 parts by weight of diacetone alcohol, and 200 parts by weight of water were further added. This was 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, the above-mentioned resist solution was spin-coated, followed by heating at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.35 μm. This resist film was exposed through an Levenson-type phase shift mask using an ArF excimer laser stepper (ISI Microstep, NA = 0.60). After exposure, baking was performed at 100 ° 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 9 seconds. Therefore, the development was performed for 18 seconds, twice as long, and then rinsed with pure water for 15 seconds. As a result, the exposure amount 30
At mJ / cm ² , a negative 0.12 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed. When the obtained substrate with the pattern was immersed in tetrahydrofuran, the pattern was instantaneously dissolved, and it was found that no cross-linking had occurred.

This resist solution was placed in a refrigerator (6 ° C.) for 1 hour.
It was found that there was no change in sensitivity and resolution even after storage for 4 days, and that storage stability was good. It was also found that storage stability was further improved as compared with a solution containing 20 parts by weight of water with respect to 100 parts by weight of the resin used in Example 1.

Example 3 100 parts by weight of the polymer having a δ-hydroxy acid structure (4d) synthesized in Synthesis Example 2 was used, and the acid generator triphenylsulfonium nonaflate 1
Parts by weight and 0.01 parts by weight of phenylpyridine were dissolved in 600 parts by weight of 1-methoxy-2-propanol, and 100 parts by weight of water were further added. This was filtered using a Teflon filter having a pore size 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 after coating, heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.35 μm. Was formed.

As in the case of the first embodiment, exposure is performed by an ArF excimer laser stepper through a phase shift mask.
A post-exposure bake was performed at 0 ° C. for 2 minutes. 23 ° C aqueous solution of tetramethylammonium hydroxide (0.048%)
When the resist film was immersed, the unexposed portion of the film was 5.0
Dissolved in seconds. Therefore, the development was performed twice as long as that for 10 seconds, followed by rinsing with pure water for 15 seconds. as a result,
At an exposure of 26 mJ / cm ² , a negative 0.12 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

The resist film was exposed through a Levenson-type phase shift mask using a KrF excimer laser stepper (NA = 0.45). After baking at 120 ° C. for 2 minutes after exposure, the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.048% by weight) at 23 ° C., and the unexposed portion of the film dissolved in 5.0 seconds. . Therefore, the development was performed twice as long as that for 10 seconds, followed by rinsing with pure water for 15 seconds. As a result, at an exposure dose of 50 mJ / cm 2, a negative 0.18 μm
An m-line and space pattern was obtained. At this time, no swelling of the pattern was observed.

This resist solution was heated at room temperature (23 ° C.).
℃) for 10 days, there is no change in sensitivity and resolution.
It was found that the storage stability was good.

<Embodiment 4> FIG. 1 shows a well-known MOS (metal-
1 shows a cross-sectional view of an (oxide-semiconductor) transistor. The transistor operates according to the voltage applied to the gate electrode 18.
The structure is such that a drain current flowing between the source electrode 16 and the drain electrode 17 is controlled.

Here, the steps for fabricating such a structure consist of dozens of steps. These steps can be broadly divided into three groups: steps up to field oxide film formation, steps up to gate formation, and final steps. You can do it. 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.

As shown in FIG. 2A, a 50 nm oxide film 22 is formed on a p-type silicon wafer 21 by a known method, and a 200 nm silicon nitride film is formed thereon by plasma CVD to form a substrate. . Example 1
A resist pattern 24 having a 0.30 μm line is formed by the materials and methods shown in FIG. 2 (FIG. 2B). After the silicon nitride film 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 as a mask again. After removing the resist (Fig. 2
(D)) A 1.2 μm field oxide film is formed in the element isolation region by selective oxidation using the silicon nitride film 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 to grow polycrystalline silicon (FIG. 2 (f)). A resist pattern of 0.12 μm line is formed on this substrate by using the pattern forming method described in the third embodiment (FIG. 2G). Using this resist pattern as a mask, the polysilicon is etched by a known method to form a gate (FIG. 2 (h)). Source,
The thin oxide film of the drain is etched, and then arsenic is diffused in the polysilicon gate, source and drain, and an oxide film is formed in the polysilicon gate, source and drain regions. The contacts for aluminum wiring to the gate, source, and drain are viewed from the opening, aluminum coating and patterning are performed, a protective film is formed, and pads for bonding are opened. 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 5 A semiconductor memory device was manufactured by using the pattern forming method shown in any one of 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 of the substrate using a known element isolation technique. Next, for example, a word line 3 having a structure in which polycrystalline Si having a thickness of 150 nm and SiO ₂ having a thickness of 200 nm is laminated.
3 is formed, and further, for example, 150 n
m ₂ SiO ₂ and anisotropically processed to form S
An iO ₂ side spacer 34 is formed. Next, the n-diffusion layer 35 is formed by a usual method. Next, as shown in FIG. 3 (b), a data line 3 made of polycrystalline Si or a refractory metal silicide or a laminated film thereof is formed through a normal process.
6 is formed. Next, as shown in FIG. 3C, a storage electrode 38 made of polycrystalline Si is formed through a normal process. After that, Ta ₂ O ₅ , Si ₃ N ₄ , SiO ₂ , BST, PZT, ferroelectric,
Alternatively, a composite film or the like is applied to form the capacitor insulating film 39. Continue with polycrystalline Si, refractory metals,
A plate electrode 40 is formed by applying a low-resistance conductor such as high-melting metal silicide or Al or Cu. Next, FIG.
As shown in (d), the 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 most of the lithography processes in the device manufacturing process, the pattern forming method described in any one of the first to third embodiments of the present invention is applied. However, the process or the pattern size that is not suitable for forming a pattern with a negative resist is not suitable. The present invention does not necessarily need to be applied to a process having a large value.
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 pattern arrangement of a memory portion of a typical pattern 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 formation of Examples 1 to 3 of the present invention was used for all except the 46 electrode extraction holes shown here. The present invention is used in processes using the minimum design rule other than the pattern formation shown here.

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 1 100 parts by weight of the polymer (3b) having a γ-hydroxy acid structure synthesized in Synthesis Example 1
2 parts by weight of an acid generator triphenylsulfonium triflate and 0.01 parts by weight of 2-benzylpyridine are dissolved in 600 parts by weight of diacetone alcohol, and filtered using a Teflon filter having a pore size of 0.20 μm without adding water. This was used as a resist solution.

The above 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 0.35 μm. This resist film was exposed through an Levenson-type phase shift mask using an ArF excimer laser stepper (ISI Microstep, NA = 0.60). After exposure, baking was performed at 100 ° 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 12 seconds. Therefore, the development was performed for 24 seconds, twice as long, and then rinsed with pure water for 15 seconds. As a result, the exposure amount 20
At mJ / cm ² , a negative 0.13 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

When this resist solution was stored in a freezer (-8 ° C.), the dissolution rate of the unexposed portion did not change for 7 days, and the sensitivity and resolution hardly changed. However, when stored in a refrigerator (6 ° C.), the time for dissolving the unexposed portion increased to 23 seconds in 3 days, making the whole less soluble, resulting in an increase in sensitivity to 15 mJ / cm ² . . However, the resolution was reduced to 0.20 μm (line and space), residues were observed between patterns, and storage stability at 6 ° C. was poor.

[0088]

EFFECT OF THE INVENTION The γ-hydroxycarboxylic acid structure or δ
A resin having a hydroxycarboxylic acid structure, and a radiation-sensitive composition containing at least a compound that generates an acid upon irradiation with actinic radiation, further containing water;
A negative-type radiation-sensitive composition that can be developed without swelling of a fine pattern in an aqueous alkaline developer and has excellent storage stability, a method of forming a pattern using the composition, and a method of manufacturing a semiconductor device using the composition. I will provide a.

[Brief description of the drawings]

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

FIG. 2 is a diagram 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 pattern layout diagram of a memory portion of a typical pattern constituting a memory element.

[Explanation of symbols]

12, 25 field oxide film, 13 source contact, 14 drain contact, 15 polycrystalline silicon, 16 source electrode, 17 drain electrode, 18 gate electrode, 19 protective film, 22 oxide film, 24 ... resist pattern, 26 ... polycrystalline silicon film, 27 ... resist pattern, 28 ... polycrystalline silicon gate, 31 ... P-type Si semiconductor substrate, 32 ... element isolation region, 33, 42 ... word line,
34 ... side spacer, 35 ... n diffusion layer, 36, 43 ...
Data lines, 38, 45: storage electrode, 39: capacitor insulating film, 40: plate electrode, 41: wiring, 44: active area, 46: electrode extraction hole.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/38 501 G03F 7/38 501 H01L 21/027 H01L 21/30 502R (72) Inventor Takashi Hattori Tokyo 1-280 Higashi-Koigakubo, Tokyo-Kokubunji-shi, Hitachi, Ltd.Central Research Laboratories Co., Ltd. 5-22-1, Mizumotocho Inside Hitachi Ultra-LII Systems Co., Ltd. (72) Inventor Toshihiko Tanaka 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 2H025 AA00 AB16 AC04 AC08 AD01 BE00 CC20 FA01 FA03 FA12 FA17 2H096 AA00 AA25 BA01 BA20 DA0 1 EA03 EA04 FA01 GA08 JA02 JA03 4J002 CF181 DE027 EV246 EV266 EV296 FD206 GP03 GQ05

Claims (10)

[Claims] (1) a γ-hydroxycarboxylic acid structure or δ-
A radiation-sensitive composition comprising a resin having a hydroxycarboxylic acid structure and at least a compound capable of generating an acid upon irradiation with actinic radiation, further comprising water. 2. The radiation-sensitive composition according to claim 1, wherein the water is contained in an amount of 5 to 500 parts by weight based on 100 parts by weight of the resin. 3. A step of forming a coating film comprising the radiation-sensitive composition according to claim 1 on a predetermined substrate, a step of heating the substrate after the formation of the coating film, and a step of forming a predetermined pattern on the coating film. A step of irradiating the substrate with an actinic radiation, a step of heating the substrate after the irradiation of the actinic radiation, and exposing the coating film to an aqueous alkali solution after the heating of the substrate to remove an unirradiated portion of the actinic radiation. Mold pattern forming method. 4. The pattern forming method according to claim 3, wherein after the step of forming the coating film comprising the radiation-sensitive composition, before the step of irradiating the coating film with actinic radiation in a predetermined pattern. And heating the coating film to reduce the water content in the coating film. 5. The pattern forming method according to claim 3, wherein the actinic radiation is far ultraviolet light having a wavelength of 250 nm or less. 6. A pattern forming method according to claim 3, wherein said active radiation is ArF excimer laser light. 7. The pattern forming method according to claim 3, wherein the active radiation of the predetermined pattern is ArF excimer laser light through a phase shift mask. 8. The pattern forming method according to claim 3, wherein said aqueous alkaline developer is an aqueous solution of tetramethylammonium hydroxide. 9. The pattern forming method according to claim 3, wherein after the step of irradiating the actinic radiation, before the step of developing a pattern on the coating film using the aqueous alkaline developer. And a step of heating the coating film. 10. A step of forming a resist pattern on a semiconductor substrate by the pattern forming method according to any one of claims 3 to 9, a step of etching the semiconductor substrate based on the resist pattern, or A method for manufacturing a semiconductor device, comprising a step of implanting ions.