JP2001255655A - Pattern forming method, method for producing semiconductor device and photosensitive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a negative type pattern which is transparent in the far UV region including 193 nm wavelength of ArF excimer laser light, does not swell while having such a chemical structure as to ensure high dry etching resistance and has superior resolution. SOLUTION: The negative type pattern which does not swell in aqueous alkali development and has high resolution is formed by using a reaction in which part or the whole of a γ- or δ-alkoxycarboxylic acid structure is converted to a lactone structure by an acid catalyzed reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlithography process using a photosensitive composition, which is a fine processing technique in a manufacturing process of a semiconductor device or the like, and a method of manufacturing a semiconductor device or the like including the microlithography process. More specifically, a negative type suitable for a photolithography process using a deep ultraviolet light having a wavelength of 220 nm or less, such as an ArF excimer laser beam, which is a line source having a shorter wavelength than a high pressure mercury lamp or a KrF excimer laser, which is a current ultraviolet light source. The present invention relates to a pattern forming method, a method for manufacturing a semiconductor device, and a photosensitive composition used for the 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 cross-linking type such as JP-A-4-165359
And a dissolution inhibiting type such as In any case, a submicron fine pattern can be formed without swelling.

[0005] 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 having a minimum processing dimension 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 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.

[0008]

In the phenol structure conventionally used as an alkali-soluble group, pKa =
In contrast to 10.0 (phenol), these carboxylic acid structures have a low value of pKa = 4.8 (acetic acid),
High acidity. 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 alkaline developer infiltrated there and swelled to form no 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.

A first object of the present invention is to provide a negative pattern forming method which can be developed without swelling of a fine pattern in an aqueous alkaline developer and which has excellent resolution performance by esterification of a material having a carboxylic acid. Is to provide. A second object of the present invention is to provide a method for manufacturing a semiconductor device using such a pattern forming method. Further, a third object of the present invention is to provide a photosensitive composition used in such a method for forming a pattern or a method for manufacturing a semiconductor device.

[0011]

In order to achieve the above-mentioned object of the present invention, a method for forming a pattern according to the present invention is directed to a method for forming a photosensitive composition comprising a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure on a predetermined substrate. A step of forming a coating film composed of a composition, and irradiating the coating film with actinic radiation of a predetermined pattern to change the carboxylic acid structure of the irradiated portion of the actinic radiation to a γ-lactone structure or a δ-lactone structure. And a step of causing

The γ- or δ-alkoxycarboxylic acid structure changes to a γ-lactone or δ-lactone structure by an acid-catalyzed reaction. Thereby, what was soluble in the aqueous alkaline developer becomes insoluble. As a result, a negative pattern is formed by development with an aqueous alkali. Generated γ
The -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. Compounds that generate an acid upon irradiation with such actinic radiation include onium salts such as triphenylsulfonium triflate, sulfonyloxyimides such as trifluoromethanesulfonyloxynaphthylimide, and sulfonate esters. Any material may be used as long as it generates an acid by irradiation with a line, for example, an ArF excimer laser.

The above γ-alkoxycarboxylic acid structure or δ-alkoxycarboxylic acid structure can be used alone or in a mixed state. In a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure, a dealcoholation reaction is caused by an acid catalyst, and intramolecular esterification is performed to form a 5- or 6-membered lactone. In this reaction, 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 exposed and unexposed parts, the penetration of the developing solution into the exposed and insolubilized parts is unlikely to occur, which is a problem of the prior art. There is no swelling of the pattern after development which was a point.

As a similar structure, the γ-hydroxy acid or δ-hydroxy acid structure also generates γ-lactone or δ-lactone by an acid-catalyzed reaction. However, γ-
The hydroxy acid or δ-hydroxy acid structure has a drawback that when it is made into a solution, its stability is low particularly at room temperature, and it gradually changes to a γ-lactone or δ-lactone structure. On the other hand, the γ-alkoxycarboxylic acid structure or δ-alkoxycarboxylic acid structure is stably present even in a solution.

The carboxylic acid structure used in the pattern forming method of the present invention has the following chemical formula (1) or (2)
It is desirable that the chemical structure represented by Here, in the formula, 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 the alkyl groups are connected to each other. May form a cyclic alkyl group. In the formula, R ⁹ represents an alkyl group having 1 to 5 carbon atoms.

[0017]

Embedded image

[0018]

Embedded image

In particular, when either R ¹ and R ³ , or R ³ and R ⁵ , or R ⁵ and R ⁷ form a cyclic alkyl group, γ-lactone or δ-lactone is structurally present. Is more preferable because a 5- or 6-membered ring of the formula (1) is easily formed.

Further, it is desirable that at least the carboxylic acid structure represented by the chemical formula (1) or (2) is contained in the film-forming component constituting the photosensitive composition. The film-forming component generally has a weight average molecular weight of 1,000.
A polymer compound having a molecular weight of about 0 to 300,000 may be used. However, the polymer compound may be an oligomer or a low molecular compound capable of forming a film, as long as it can be coated 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.

When the carboxylic acid structure represented by the above formula (1) or (2) is contained in the polymer compound and is directly contained in the main chain, the carboxylic acid structure is stereoscopically expressed in the above formula (1) or (2). In some cases, the carboxylic acid portion and the alkoxy group portion may be distant, and the lactonization reaction may not easily occur. On the other hand, when the carboxylic acid structure represented by the above chemical formula (1) or (2) is included in the side chain, the carboxylic acid portion and the alkoxy group portion are hardly distant from each other in a steric manner, so that the lactonization occurs. This is more preferable because it easily occurs and a pattern can be formed with high sensitivity.

The above 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.
Since these structures have high dry etching resistance and are 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.

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

When irradiating a predetermined pattern of actinic radiation in the present invention, 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 preferable 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 for developing 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 acid-catalyzed dealcoholization reaction that produces lactone proceeds more efficiently.

In order to achieve the object of the present invention, a method of manufacturing a semiconductor device according to the present invention comprises forming a resist pattern on a semiconductor substrate by any of the pattern forming methods described above, And 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 method of manufacturing a semiconductor device according to 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 of manufacturing a semiconductor device according to 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.

As described above, the photosensitive composition of the present invention comprises a compound having a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure as an alkali-soluble group, and a compound capable of generating an acid upon irradiation with actinic radiation. It is intended to include at least.

The carboxylic acid structure is desirably contained in a film forming component constituting the photosensitive composition. The film-forming component generally has a weight average molecular weight of 1,000 to 3,
Although a high molecular compound of about 000 is mentioned, it is not limited to a high molecular compound as long as it can be coated with a solvent, and may be an oligomer or a low molecular compound capable of forming a film. 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.

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, sulfonyloxyimides such as N-methanesulfonyloxynaphthylimide, N-trifluoromethanesulfonyloxysuccinimide, N-perfluorooctanesulfonyloxysuccinimide, and sulfonate 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. These acid generators may be used in combination of two or more.

The acid generator is preferably used in an amount of 0.1 to 50 parts by weight, and more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the film-forming component of the photosensitive composition. It is more preferable to use it.

Further, the photosensitive composition of the present invention has two components for improving resolution, process stability and storage stability.
-Basic compounds such as benzylpyridine, phenylpyridine, tripentylamine, triethanolamine,
Salts such as tetramethylammonium iodide, tetrapentylammonium chloride and 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 hexamethoxymethyl melamine, 1,3,4,6-tetrakis (methoxymethyl) glucoluril and 1,3,4,6-tetrakis (methoxymethyl) glucoluril in order to enhance the heat resistance of the formed pattern. 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.

The photosensitive composition of the present invention is used by dissolving it in a solvent and spin-coating it on a substrate as a solution. At this time, any solvent may be used as long as the above components are sufficiently dissolved and a uniform coating film can be formed by spin coating, and they may be used alone or as a mixture of two or more.

[0038]

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 (3c) having γ-methoxycarboxylic acid structure 5-Methylenebicyclo [2.2] was placed in a 500 ml three-necked flask equipped with a thermometer, a cooling tube and a nitrogen inlet tube. .1] 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 to precipitate a polymer, which was dried and dried with 5-methylenebicyclo [2.2.
1] 19.4 g of hept-2-ene-citraconic anhydride copolymer (3a) was obtained (yield 38%).

The structure of the obtained polymer was found to be mainly the structure of the following chemical formula (3a) from various analytical methods (where n represents an integer).

[0041]

Embedded image

When the molecular weight of this polymer in tetrahydrofuran was measured 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, 3.0 g of sodium borohydride and 100 g of tetrahydrofuran were placed, cooled to 0 ° C. by an ice bath, and stirred under nitrogen to obtain 5-methylenebicyclo [2. 2.
1] Hept-2-ene-citraconic anhydride copolymer 1
A solution of 7.4 g 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 above 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 to this solution and extraction was performed twice, and the obtained organic layer was washed three times with 150 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate, and the solvent was further reduced by distillation under reduced pressure. The residue 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 obtained polymer has a structure in which the anhydride portion of the chemical formula (3a) has been reduced to form a lactone, and a compound having at least a ring-opened γ-hydroxy acid structure. It was found to be a polymer represented by the chemical formula (3b) shown in Chemical formula 6 or Chemical formula 7 (wherein, l and m represent integers).

[0046]

Embedded image

[0047]

Embedded image

Next, 6.0 g of sodium hydroxide was added to 10 parts of water.
9.2 g of the polymer (3b) was dispersed in 0 ml of the solution, and 13.2 g of dimethyl sulfate was added dropwise at room temperature. After the dropwise addition, the solution was heated to reflux and reacted for 5 hours.
In about 30 minutes after the heating was started, the polymer was changed from the dispersed state to the uniform state.

After the reaction, 200 ml of water was added, and about 0.
A 5N hydrochloric acid aqueous solution was gradually added to make the solution weakly acidic at about pH 4. 120 ml of ethyl acetate and 60 ml of tetrahydrofuran were added to this solution, and the mixture was extracted twice, and the obtained organic layer was washed three times with 150 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The solvent was reduced and poured into 700 ml of n-hexane. The precipitated polymer was dried to obtain 7.9 g of a milky white powdery polymer. From various analyses, the structure of the obtained polymer was found to be a polymer having a γ-methoxy acid structure and having the chemical formula (3c) shown in Chemical formula 8 or Chemical formula 9 (wherein, 1 and m are integers) Represents).

[0050]

Embedded image

[0051]

Embedded image

100 parts by weight of the obtained polymer (3c) was dissolved in 600 parts by weight of diacetone alcohol, and the pore size was adjusted to 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.

The film (film thickness 410 nm) applied on the substrate is coated with an aqueous solution of tetramethylammonium hydroxide (concentration 2.
(38% by weight), it melted in 5.2 seconds while the interference color changed, and the residual film became zero. In addition, when the solubility was examined using a dissolution rate monitor, it was found that the dissolution occurred sequentially from the surface formation without swelling. When immersed in a diluted aqueous solution of tetramethylammonium hydroxide (concentration: 0.113% by weight), no dissolution occurred.

When the absorption spectrum of the film coated on the lithium fluoride substrate was measured with a vacuum ultraviolet spectrometer (manufactured by ARC), the absorbance at 193 nm was 0.75 at a film thickness of 1.0 μm. It turned out to be small.

<Synthesis Example 2> Synthesis of polymer (4c) having γ-ethoxycarboxylic acid structure Polymerization was carried out 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 give 5-methylene. 37.5 g of bicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (4a) was obtained (yield: 92).
%).

The structure of the obtained polymer was found to be mainly the structure of the chemical formula (4a) shown in the following formula 10 from various analytical methods (where n represents an integer). In addition, 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.

[0057]

Embedded image

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 (4).
Chemical formula (4b) represented by chemical formula (4b) having a structure in which the anhydride portion of a) is reduced and lactonized, and which has at least a ring-opened γ-hydroxy acid structure.
(Wherein l and m represent integers).

[0059]

Embedded image

[0060]

Embedded image

Next, 6.0 g of sodium hydroxide was added to 10 parts of water.
In a 0 ml solution, 10.0 g of the polymer (4b) was dispersed, and 17.3 g of diethyl sulfate was added dropwise at room temperature. After the dropwise addition, the solution was heated to reflux and reacted for 5 hours.
In about 30 minutes after the heating was started, the polymer was changed from the dispersed state to the uniform state.

After the reaction, 200 ml of water was added, and about
A 5N hydrochloric acid aqueous solution was gradually added to make the solution weakly acidic at about pH 4. 120 ml of ethyl acetate and 60 ml of tetrahydrofuran were added to this solution, and the mixture was extracted twice, and the obtained organic layer was washed three times with 150 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate, and the solvent was further reduced by distillation under reduced pressure. The residue was poured into 700 ml of n-hexane, and the precipitated polymer was dried to obtain 8.9 g of a milky white powdery polymer. According to various analytical methods, the structure of the obtained polymer was represented by the chemical formula (4) having a γ-ethoxy acid structure shown in Chemical formula 13 or Chemical formula 14.
c) (wherein l and m represent integers).

[0063]

Embedded image

[0064]

Embedded image

100 parts by weight of the obtained polymer (4c) was dissolved in 600 parts by weight of diacetone alcohol, and the pore size was adjusted to 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.

A film applied on the substrate (film thickness 470 nm)
Was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.113% by weight) and dissolved 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,
The dissolution rate could not be measured.

When the absorption spectrum of the film coated on the lithium fluoride substrate was measured with a vacuum ultraviolet spectrometer (manufactured by ARC), the absorbance at 193 nm was 0.82 at a film thickness of 1.0 μm. It turned out to be small.

Synthesis Example 3 Synthesis of Polymer (5e) Having δ-Methoxycarboxylic Acid Structure 9.6 g of testosterone, 11.4 g of dicyclohexylcarbodiimide and 0.53 g of 4-pyrrolidinopyridine were dissolved in 120 g of tetrahydrofuran. 4.6 g of methacrylic acid was dripped there. After the dropwise addition, the mixture was stirred at room temperature for about 4 hours to react, and then the precipitated salt, dicyclohexylurea, was separated by filtration and 250 ml of diethyl ether was added to the filtrate.
And the filtrate is washed twice with 100 ml of a 5% aqueous acetic acid solution, and then with 100 ml of a 0.5N aqueous sodium hydrogen carbonate solution.
After washing twice with 100 ml of water at the end,
The solution was dried over sodium sulfate. After drying the solution, sodium sulfate was filtered off and the solution was distilled off under reduced pressure. Then, recrystallization was performed with ethyl acetate to obtain 8.4 g of testosterone methacrylate (5a) (yield: 70%).

A thermometer, a cooling pipe and a nitrogen introduction pipe were attached.
In a 0 ml three-necked flask, 8.0 g of the synthesized testosterone methacrylate (5a), 0.48 g of dimethyl-2,2'-azobis (isobutyrate), and 150 g of tetrahydrofuran were placed, and heated to 70 ° C. while introducing nitrogen. And polymerized for 7 hours. After polymerization, n-hexane 10
The solution was poured into 100 ml of the solution, and the polymer was precipitated and dried. The testosterone polymethacrylate (5b, n
7.6 g was obtained (95% yield).

[0070]

Embedded image

When the molecular weight of this polymer in terms of polystyrene was examined in gel permeation chromatography (GPC) in tetrahydrofuran, the weight average molecular weight was 8,000 and the number average molecular weight was 6,000.

Next, the obtained polymer was subjected to Lemieux.
The double bond of the testosterone structure was converted to a δ-ketocarboxylic acid structure by -von Rudoff oxidation. 7.5 g of testosterone polymethacrylate (5b) and 150 m of tetrahydrofuran are placed in a 500 ml flask.
l, 50 ml of t-butanol was added, and a solution obtained by dissolving 3.75 g of potassium carbonate in 30 ml of water was added thereto. Separately,
Dissolve 27g of sodium periodate in 160ml of water,
An aqueous sodium periodate solution was prepared, of which 40
ml was added to the previous polymer solution at room temperature.

Subsequently, 4 ml of a separately prepared solution of 0.165 g of potassium permanganate dissolved in 12 ml of water was added to the above polymer solution at room temperature. Next, 60 ml of the remaining aqueous solution of sodium periodate was added dropwise over about 10 minutes, and 60 ml of the remaining aqueous solution of sodium periodate was added dropwise over the next 30 minutes. When the aqueous solution of sodium periodate was dropped, the remaining aqueous solution of potassium permanganate was sometimes added so that the polymer solution during the reaction remained purple.

After the aqueous solution of sodium periodate was added dropwise, the mixture was stirred at room temperature for several hours, cooled with ice, and an aqueous solution of sodium hydrogen sulfite was added until the brown reaction solution became purple. Further, a 1N aqueous solution of sulfuric acid was added to the solution to make the solution acidic to about pH 3. Diethyl ether was added to the reaction solution, and 100 ml
After extraction three times, the ether solution was washed twice with 100 ml of a 5% aqueous sodium bisulfite solution. The ether solution became purple to colorless when washed with an aqueous solution of sodium hydrogen sulfite. After washing the ether solution three times with 100 ml of water, the solution was dried over magnesium sulfate.

After drying, the magnesium sulfate was filtered off, the solvent was distilled off under reduced pressure and concentrated to about 100 ml, then poured into 500 ml of n-hexane, and the precipitated polymer was dried to obtain 7.0 g of a white powdery polymer. Obtained. According to various analytical methods, the structure of the obtained polymer is represented by the chemical formula (5c, n is an integer) represented by Chemical Formula 16 in which the double bond of testosterone (5b) is oxidized to open the ring to form a δ-ketocarboxylic acid structure. ).

[0076]

Embedded image

Next, 6.8 g of the obtained polymer (5c) was obtained.
Was dissolved in 100 ml of tetrahydrofuran, and a solution prepared by dissolving 0.68 g of sodium borohydride in 10 ml of water was added dropwise at room temperature. After the dropwise addition, the mixture was stirred for several hours, 100 ml of water was added, and a 0.5N aqueous hydrochloric acid solution was further added to add p.
It was made weakly acidic to about H4. Thereafter, 100 ml of ethyl acetate and 50 ml of tetrahydrofuran were added to this solution, and extraction was performed twice. After extraction, the organic layer was washed three times with 100 ml of water, dried over sodium sulfate, filtered to remove sodium sulfate, further distilled off the solvent under reduced pressure, concentrated to about 100 ml, and then diluted with about 300 ml of n-hexane. , And the precipitated polymer was dried to obtain 6.0 g of a white powdery polymer. Polymers obtained by various analytical methods have a δ-hydroxy acid structure in which the ketone structure of (5c) is reduced.
The polymer was found to be a polymer having the chemical formula (5d, n represents an integer) shown in FIG.

[0078]

Embedded image

Next, 3.0 g of sodium hydroxide was added to 20 parts of water.
5.5 g of the polymer (5d) was dispersed in 0 ml of the solution, and 4.6 g of dimethyl sulfate was added dropwise thereto at room temperature.
After the dropwise addition, the solution was heated to reflux and reacted for 8 hours. In about 30 minutes after the heating was started, the polymer was changed from the dispersed state to the uniform state.

After the reaction, about 0.5N aqueous hydrochloric acid was gradually added to the reaction solution to make it weakly acidic at about pH 4. 120 ml of ethyl acetate and 60 ml of tetrahydrofuran were added to this solution, and the mixture was extracted twice, and the obtained organic layer was washed three times with 150 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate, and the solvent was further distilled off under reduced pressure. The residue was poured into 400 ml of n-hexane, and the precipitated polymer was dried to obtain 5.0 g of a milky white powdery polymer. The structure of the obtained polymer was determined from various analytical methods according to the chemical formula (5e, n represents an integer) having a δ-methoxycarboxylic acid structure shown in Chemical formula 18.
Was found to be a polymer.

[0081]

Embedded image

100 parts by weight of the obtained polymer (5e) was dissolved in 600 parts by weight of 1-methoxy-2-propanol and filtered with a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a polymer film. The film applied on the substrate (film thickness 40
(0 nm) was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 2.38% by weight). In addition, when the solubility was examined using a dissolution rate monitor, it was found that the substance was dissolved without swelling.

When the absorption spectrum of the film coated on the lithium fluoride substrate was measured with a vacuum ultraviolet spectrometer (manufactured by ARC), the absorbance at 193 nm was 0.25 at a film thickness of 1.0 μm. It turned out to be small.

<Synthesis Example 4> Synthesis of compound (6e) having δ-methoxycarboxylic acid structure Esterification of 7.1 g of testosterone using 10.4 g of dehydrocholic acid instead of methacrylic acid used in Synthesis Example 3. As a result, 13.0 g of testosterone dehydrocholate of the chemical formula (6a) shown in Chemical formula 19 was obtained.

[0085]

Embedded image

Using 12.5 g of the obtained testosterone dehydrocholate (6a), the Lemieux-von Rudoff oxidation shown in Synthesis Example 3 was carried out in the same manner, and instead of reprecipitation with diethyl ether / n-hexane. Then, diethyl ether was distilled off, and the residue was recrystallized from ethanol to obtain 10.7 g of a compound (6b) having a δ-ketocarboxylic acid structure shown in Chemical formula 20.

[0087]

Embedded image

Next, 10.0 g of the compound having a δ-ketocarboxylic acid structure (6b) was reduced with sodium borohydride in the same manner as in Synthesis Example 3 to obtain a compound having the δ-hydroxy acid structure shown in Chemical Formula 21. Compound (6c) 8.
5 g were obtained.

[0089]

Embedded image

Further, using 8.0 g of the compound (6c) having a δ-hydroxycarboxylic acid structure, methyl etherification with dimethyl sulfate was carried out in the same manner as in Synthesis Example 3 to obtain a δ-methoxycarboxylic acid structure shown in Chemical formula 22. The obtained compound (6d) (7.4 g) was obtained.

[0091]

Embedded image

Example 1 100 parts by weight of the polymer having a γ-methoxycarboxylic acid structure (3c) synthesized in Synthesis Example 1, 2 parts by weight of an acid generator triphenylsulfonium triflate, 0.01 part by weight of 2-benzylpyridine Was dissolved in 600 parts by weight of diacetone alcohol, and the pore size was 0.20.
Filtration was performed using a μm Teflon filter 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.

ArF excimer laser stepper (ISI
The resist film was exposed to light through a Levenson-type phase shift mask using 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 8 seconds. Therefore, the development was performed for 16 seconds, twice as long, and then rinsed with pure water for 15 seconds.

As a result, a negative 0.12 μm line and space pattern was obtained at an exposure dose of 25 mJ / cm ² . At this time, no swelling of the pattern was observed. In addition,
When the obtained substrate having the pattern was immersed in tetrahydrofuran, the pattern was instantaneously dissolved, and it was found that no cross-linking had occurred. It was also found that this resist solution had no change in sensitivity and resolution even when stored in a refrigerator (6 ° C.) for 14 days, and had good storage stability.

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 1.22 when the commercially available novolak resin was 1.0, indicating that the resist had sufficiently high dry etching resistance for practical use.

The resist applied on the NaCl plate was
Similarly, irradiation with ArF excimer light was performed at 25 mJ / cm ² , and infrared absorption spectra before and after baking after exposure were measured by FT-1720X manufactured by Perkin Elmer. As a result, after the post-exposure bake, 346
It was found that the peak around 6 cm ^-1 was greatly reduced. It was also found that the peak at 1712 cm ^-1 due to lactone had increased.

The resist film initially had the structure of the polymer (3c) having a γ-methoxycarboxylic 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 structure of γ-methoxycarboxylic acid in the polymer undergoes a de-methanol reaction in the molecule to esterify it, resulting in a γ-lactone structure. As a result, the exposed portion became insoluble in the alkali developing solution, and a negative pattern was formed. At this time, the mechanism of the negative mold was not a crosslinking reaction but a large decrease in the amount of the carboxylic acid due to the lactonization, so that no swelling occurred and a fine pattern could be formed.

<Example 2> In place of the polymer (3c) having a γ-methoxycarboxylic acid structure used in Example 1, 100% of the compound (4c) having a γ-ethoxycarboxylic acid structure synthesized in Synthesis Example 2 was used. Parts by weight, 3 parts by weight of an acid generator triphenylsulfonium nonaflate and 0.01 parts by weight of tetrapentylammonium chloride are dissolved in 600 parts by weight of cyclohexanone, and filtered using a Teflon (registered trademark) filter having a pore size of 0.20 μm, A resist solution was used.

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 0.30 μm. Was formed.

Exposure was carried out through a chromium mask using an ArF excimer laser stepper in the same manner as in Example 1, and then baking was carried out at 100 ° C. for 2 minutes. 23 ° C. tetramethylammonium hydroxide aqueous solution (0.11
(3% by weight), the unexposed portion of the film dissolved in 10 seconds. Therefore, the development was carried out for about 20 times, which is twice as long as that, followed by rinsing with pure water for 15 seconds.
As a result, at an exposure amount of 40 mJ / cm ² , a negative type 0.1
A 6 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed. It was also found that this resist solution had no change in sensitivity and resolution even when stored in a refrigerator (6 ° C.) for 14 days, and had good storage stability.

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 1.25, assuming that the etching rate of a commercially available novolak resin coating film was 1.0, indicating that the dry etching resistance was high.

Example 3 The polymer (5e) having a δ-methoxycarboxylic acid structure synthesized in Synthesis Example 3 was added to 100
Parts by weight, 3 parts by weight of an acid generator, triphenylsulfonium triflate, and 0.015 parts by weight of phenylpyridine.
It was dissolved in 600 parts by weight of methoxy-2-propanol 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 after the coating, the resist solution was heated 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. 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 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, a negative 0.12 μm line and space pattern was obtained at an exposure dose of 28 mJ / cm ² . At this time, no swelling of the pattern was observed. It was also found that this resist solution had no change in sensitivity and resolution even when stored in a refrigerator (6 ° C.) for 14 days, and had good storage stability.

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 (2.38% by weight) at 23 ° C., and the unexposed portion of the film was 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, a negative 0.18 μm line and space pattern was obtained at an exposure dose of 50 mJ / cm ² . At this time, no swelling of the pattern was observed. This resist solution showed no change in sensitivity and resolution even when stored at room temperature (23 ° C.) for 7 days, indicating that storage stability was good.

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 1.23 when the etching rate of a commercially available novolak resin coating film was 1.0, indicating that the dry etching resistance was high.

Example 4 100 g of the polymer (3c) having a γ-methoxycarboxylic acid structure synthesized in Synthesis Example 1 was used.
Parts by weight, 3 parts by weight of an acid generator, trifluoromethanesulfonyloxysuccinimide, and 10 parts by weight of 1,3,4,6-tetrakis (methoxymethyl) glucoluril are dissolved in 600 parts by weight of diacetone alcohol, and the pore size is 0.20 μm.
It was filtered using a Teflon filter of m 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 after coating, heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.30 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. 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 5.0 seconds. Therefore, the development was performed twice as long as that for 10 seconds, followed by rinsing with pure water for 10 seconds.

As a result, a negative 0.13 μm line and space pattern was obtained at an exposure amount of 35 mJ / cm ² . At this time, no swelling of the pattern was observed. It was also found that this resist solution had no change in sensitivity and resolution even when stored in a refrigerator (6 ° C.) for 14 days, and had good storage stability.

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 1.20 when the etching rate of a coating film of a commercially available novolak resin was 1.0, indicating that the resist had sufficiently high dry etching resistance for practical use. .

Example 5 100 g of the polymer (3c) having a γ-methoxycarboxylic acid structure synthesized in Synthesis Example 1 was used.
Parts by weight, 20 parts by weight of the compound having a δ-methoxycarboxylic acid structure (6d) synthesized in Synthesis Example 4, 3 parts by weight of an acid generator dimethylphenylsulfonium triflate, 0.015 parts by weight of tetraethylphosphonium iodide, and diacetone alcohol Dissolved in 600 parts by weight, pore size 0.20μm
And filtered using a Teflon filter 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 the application, heat-treated at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.33 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. 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 was dissolved in 4.0 seconds. Therefore, the development was performed for 2.5 seconds, 10 seconds, followed by rinsing with pure water for 10 seconds.

As a result, a negative 0.13 μm line and space pattern was obtained at an exposure dose of 27 mJ / cm ² . At this time, no swelling of the pattern was observed. It was also found that this resist solution had no change in sensitivity and resolution even when stored in a refrigerator (6 ° C.) for 14 days, and had good storage stability.

The resist film was exposed to a line and space pattern using an electron beam lithography apparatus with an acceleration voltage of 50 kV. Baking and development after exposure were performed under the same conditions as in the ArF excimer laser exposure.
/ Cm ² , a negative type 0.13 μm line and space pattern was obtained. 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 1.18, when the etching rate of a commercially available novolak resin coating film was 1.0,
It was found that the film had sufficiently high dry etching resistance for practical use.

Embodiment 6 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.

The process of forming such a structure comprises over a dozen steps, which can be broadly summarized as three steps, ie, a step up to formation of a field oxide film, a step up to gate formation, and a final step.
They can be divided into groups. 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.

By 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 is formed thereon by plasma CVD to form a substrate.

A resist pattern 24 having a 0.30 μm line was formed on the substrate by using the material and method described in the first embodiment.
Is formed (FIG. 2B). This resist pattern 24
After the silicon nitride film 23 is etched by a known method using the mask as a mask (FIG. 2C), boron ion implantation for a channel stopper is performed again using the resist 24 as a mask.

After removing the resist 24 (FIG. 2)
(D)) 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. That is, after etching the silicon nitride film 23, the gate is oxidized to grow the polycrystalline silicon 26 (FIG. 2 (f)). A resist pattern 27 having a 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 27 as a mask, the polycrystalline silicon 26 is etched by a known method to form a gate 28 (FIG. 2 (h)).

In the following steps, although not shown, the thin oxide film of the source and the drain is etched, and then arsenic is diffused into the polycrystalline silicon gate and the source and the drain.
An oxide film is formed on the polycrystalline silicon gate and the source and drain regions. Open contacts for aluminum wiring to the gate, source, and drain, perform aluminum deposition and patterning, further form a protective film, and open pads for bonding.

As described above, the MOS transistor shown in FIG. 1 is formed. Here, a method of forming a field oxide film has been particularly described for a MOS transistor. However, it is needless to say that the present invention is not limited to this, but can be applied to other semiconductor element manufacturing methods and processes.

Embodiment 7 A semiconductor memory device was manufactured by using the pattern forming method described in any of Embodiments 1 to 5 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, a word line 33 having a structure in which, for example, polycrystalline Si having a thickness of 150 nm and SiO ₂ having a thickness of 200 nm is laminated is formed, and further, for example, SiO ₂ having a thickness of 150 nm is deposited by using a chemical vapor deposition method. Then, a side spacer 34 of SiO ₂ is formed on the side wall of the word line.

Next, an 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 high melting point 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 method described in any one of Embodiments 1 to 3 of the present invention was applied to most of the processes. However, a process not suitable for forming a pattern with a negative resist was used. It is not always necessary to apply the present invention 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 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,
5 is a storage electrode, and 46 is a pattern of an electrode extraction hole.
Also in this example, the pattern forming methods of Examples 1 to 3 of the present invention were used for all steps except for 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 were 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.

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, and the whole became difficult to dissolve. As a result, the sensitivity was increased to 15 mJ / cm ² . However, it was found that the resolution was reduced to 0.14 μm (line and space) and the storage stability was poor at 6 ° C.

[0140]

According to the present invention, by using lactonization of a resin having an alkoxycarboxylic acid structure, even in a photolithography process using far ultraviolet rays having a wavelength of 220 nm or less, development can be performed without swelling of a fine pattern with an aqueous alkali developer. A negative pattern forming method with excellent image performance can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a MOS transistor.

FIG. 2 is a sectional view showing a transistor forming process according to one embodiment of the present invention.

FIG. 3 is a sectional view illustrating a manufacturing process of a semiconductor memory device according to an embodiment of the present invention;

FIG. 4 is a plan view showing a typical pattern arrangement of a memory section of 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 line, 38, 45 storage electrode, 39 insulating film for capacitor, 40 plate electrode, 41 wiring, 44
... active area, 46 ... electrode extraction hole.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Shiraishi 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 2H025 AA02 AA08 AB16 AC04 AC08 AD01 BD02 BE00 BE07 BE10 CB43 FA12 FA17 FA41 2H096 AA25 BA01 BA06 EA03 EA05 FA01 GA09 HA23 HA30

Claims (13)

[Claims] 1. A step of forming a coating film comprising a photosensitive composition containing a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure on a substrate, and irradiating the coating film with actinic radiation of a predetermined pattern. Changing the carboxylic acid structure of the irradiated portion of the actinic radiation to a γ-lactone structure or a δ-lactone structure. 2. The method for forming a pattern according to claim 1, wherein the γ-alkoxycarboxylic acid or δ-alkoxycarboxylic acid structure has a chemical structure represented by the following chemical formula (1) or (2): 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. Wherein R ⁹ is
Which represents an alkyl group having 1 to 5 carbon atoms). Embedded image Embedded image 3. The pattern forming method according to claim 2, wherein the photosensitive composition contains a polymer compound, and at least the polymer compound has a carboxylic acid structure represented by the chemical formula (1) or (2). A pattern forming method comprising: 4. The pattern forming method according to claim 1, wherein the photosensitive composition containing a carboxylic acid structure further contains an alicyclic structure. 5. The pattern forming method according to claim 1, 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 1, wherein the actinic radiation is ArF excimer laser light. 7. The pattern forming method according to claim 1, 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 1, further comprising, after the step of irradiating the actinic ray, developing a pattern on the coating film using an aqueous alkaline developer. A method for forming a pattern, wherein the aqueous alkaline developer is an aqueous solution of tetraalkylammonium hydroxide. 9. The pattern forming method according to claim 8, wherein after the step of irradiating the actinic radiation, before the step of developing the pattern on the coating film using the aqueous alkaline developer, A method for forming a pattern, comprising a step of heating a 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 1 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. 11. A photosensitive composition comprising at least a compound having a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure as an alkali-soluble group, and a compound capable of generating an acid upon irradiation with active actinic radiation. . 12. The photosensitive composition according to claim 11, wherein the compound having a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure as the alkali-soluble group further contains an alicyclic structure. Photosensitive composition. 13. The photosensitive composition according to claim 11, wherein the compound having a γ-alkoxycarboxylic acid structure or a δ-alkoxycarboxylic acid structure as the alkali-soluble group is a high molecular compound. Photosensitive composition.