JP2001235861A - Pattern forming method and method for producing semiconductor device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a negative pattern which is transparent in the far UV region of <=250 nm wavelength in exposure, does not swell while having a chemical structure with high dry etching resistance and is excellent in resolving power. SOLUTION: The pattern forming method includes a step for coating a substrate with a photosensitive composition containing a ketocarboxylic acid having a ν- or δ-ketocarboxylic acid structure and an acid generating agent which generates an acid by exposure, a step for selectively exposing the resulting coating film to make the exposed region insoluble in a developing solution and a step for developing the coating film with the developing solution. The ketocarboxylic acid in the photosensitive composition is converted to an enol lactone structure insoluble in the developing solution by the action of the acid generated from the acid generating agent in exposure. The ketocarboxylic acid in the exposed region forms the enol lactone structure insoluble in the developing solution because a carboxyl group and a ketone molecule in the same molecule cause esterification reaction under the action of the generated acid. For example, exposure with ArF excimer laser beam of 193 nm wavelength and development with an alkali solution are carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pattern and a method for manufacturing a semiconductor device using the same. The present invention relates to a negative-type pattern forming method suitable for a photolithography process using far-ultraviolet light having a wavelength of 250 nm or less such as a laser beam and a method for manufacturing a semiconductor device using the same.

[0002]

2. Description of the Related Art A photolithography technique for forming a microscopic pattern on the order of microns or submicrons in an electronic device such as a semiconductor device has played a central role in mass production fine processing technology. The recent demand for higher integration and higher density of semiconductor devices has brought many advances in fine processing technology. In particular, as the minimum processing dimension approaches the exposure wavelength, the g-line (436 nm) and i-line (365 nm)
Photolithography techniques using an rF excimer laser (248 nm) and a shorter wavelength light source have been developed.

[0003] In response to these changes in the exposure wavelength, photoresists have been developed with materials corresponding to the respective wavelengths. Conventionally, in photoresists suitable for these wavelengths,
Although the sensitizer and the sensitizing mechanism are different from each other, aqueous alkali development utilizing aqueous alkali solubility of a resin or polymer material having a phenol structure has been industrially used. These resins or polymer materials inevitably contain a large number of aromatic rings, which are also chemical structural elements that enhance 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, for example, JP-A-62-1.
There are a cross-linking type as described in 64045 and a dissolution-inhibiting type as described in JP-A-4-165359. In any case, the obtained resist pattern can form a submicron fine pattern 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 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
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, for example, use of an adamantane skeleton is disclosed in
39665, JP-A-5-265212,
Similarly, the use of a norbornane skeleton is disclosed in JP-A-5-80515.
And JP-A-5-257284.

[0007] 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. .

A polymer having a chemical structure transparent in a deep ultraviolet region including a wavelength of 193 nm of an ArF excimer laser,
Regarding the resist material which is made developable with aqueous alkali, see, for example, JP-A-4-39665 and JP-A-4-4-1.
No. 84345, JP-A-4-226461, JP-A-5-80515, etc.
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. JP-A-8-259626 discloses a polymer compound in which a carboxylic acid group is added to an alicyclic structure introduced into a methacrylic acid ester side chain.

[0009]

In the phenol structure conventionally used as an alkali-soluble group, pKa = 1
In contrast to 0.0 (phenol), these carboxylic acid structures have a low pKa = 4.8 (acetic acid) and a high acidity. Therefore, when they are used as alkali-soluble groups of the base resin, generally at the same mole fraction,
A resin having a carboxylic acid structure has a higher dissolution rate in an aqueous alkali, and a resin having a carboxylic acid structure dissolves even in a low-concentration alkaline developer in which a resin having a phenol structure does not dissolve.

When a resin having a carboxylic acid as described above is used, a carboxylic acid having a high acidity remains in a cross-linked portion when a cross-linking agent as disclosed in, for example, JP-A-62-164045 is used. For this reason, there is a disadvantage that the alkaline developer infiltrates there, swells and a fine pattern cannot be formed.

Further, as shown in, for example, Japanese Patent Application Laid-Open No. 4-165359, when a compound having a dissolution inhibiting action is formed by an acid generated by exposure, a resin having a carboxylic acid has a dissolution contrast. There was a drawback that it did not form a negative resist.

Accordingly, a first object of the present invention is to provide a pattern forming method capable of developing a fine pattern without swelling with an aqueous alkaline developer, specifically, an intramolecular esterification reaction of a material having a carboxylic acid by exposure treatment. To provide a pattern forming method capable of forming a negative pattern having excellent resolution performance.

It is a second object of the present invention to provide a method for manufacturing a semiconductor device using such a pattern forming method.

[0014]

Means for Solving the Problems In order to achieve the first object, a pattern forming method of the present invention comprises a step of forming a coating film made of a photosensitive composition on a predetermined substrate; An exposure step of insolubilizing an exposed area with a developer by selectively exposing the film, and a pattern forming method including a step of developing the exposed area with a developer, wherein the photosensitive composition has γ A photosensitive composition comprising at least one kind of ketocarboxylic acid having a -ketocarboxylic acid structure and a δ-ketocarboxylic acid structure and an acid generator that generates an acid upon exposure.

That is, in the exposure step, the ketocarboxylic acid in the exposed region of the coating film undergoes an intramolecular esterification reaction due to the action of an acid generated from the acid generator (by an acid catalyzed reaction), and the ketocarboxylic acid structure is removed. Enol-γ-lactone structure in which part or all is a carboxylic acid ester structure (5
Membered ring) or enol-δ-lactone structure (6-membered ring)
And what was soluble in the aqueous alkaline developer becomes insoluble.

That is, by the action of the acid generated from the acid generator during the exposure treatment, the carboxyl group and the ketone group of the ketocarboxylic acid undergo an esterification reaction (dehydration reaction) in the molecule, and as a result, a five-membered ring structure is formed. When it is formed, it has an enol-γ-lactone structure, and when it has a 6-membered ring structure, it has an enol-δ-lactone structure. The enol-lactone structure means a lactone structure having a double bond.

As a result, a negative pattern is formed by development with an aqueous alkali. The resulting enol-γ-lactone or enol-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 by irradiation with active actinic radiation (far ultraviolet light having a wavelength of 250 nm or less) as exposure light at the time of exposure.

Examples of this type of acid generator include onium salts such as triphenylsulfonium triflate, sulfonyloxyimides such as trifluoromethanesulfonyloxynaphthylimide, and sulfonic acid esters. Any material that generates an acid by irradiation with a certain actinic ray, for example, an ArF excimer laser (wavelength 193 nm) or the like may be used.

The ketocarboxylic acid structure for producing an enol-γ-lactone structure or an enol-δ-lactone structure by exposure as described above is preferably a γ-ketocarboxylic acid structure or a δ-ketocarboxylic acid structure. Each of these γ-ketocarboxylic acid structures or δ-ketocarboxylic acid structures can be used alone, or both can be used in a mixed state.

In a γ-ketocarboxylic acid structure or a δ-ketocarboxylic acid structure, a 5- or 6-membered ring can be formed by intramolecular esterification by an acid-catalyzed reaction at the time of exposure.
Enol lactonization readily occurs. Since this reaction is an intramolecular esterification reaction, the number of carboxylic acids is greatly reduced by the reaction at the time of exposure. Therefore, the reaction at the time of exposure occurs between molecules, and the amount of carboxylic acid is different from the conventional crosslinking reaction in which the amount of carboxylic acid hardly changes between exposed and unexposed portions. Is less likely to occur, and there is no swelling of the pattern after development, which is a problem of the prior art.

The present inventors have previously proposed a γ-hydroxy acid or δ-hydroxy acid structure as a similar structure to the above ketocarboxylic acid, and these are also γ-lactone or δ-hydroxy acid.
The lactone is produced by an acid-catalyzed reaction. However, these γ-hydroxy acid or δ-hydroxy acid structures
When made into a solution, it has low stability at room temperature and gradually changes to a γ-lactone or δ-lactone structure. Therefore, when used as a resist solution, there is a drawback that storage stability is poor if used as it is.

On the other hand, the ketocarboxylic acid having a γ-ketocarboxylic acid structure or a δ-ketocarboxylic acid structure of the present invention is stably present in a solution.

The ketocarboxylic acid having a ketocarboxylic acid structure used in the pattern forming method of the present invention preferably has a chemical structure represented by the following formula (1) or (2).

[0024]

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[0025]

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Wherein R ¹ in the formula represents an alkyl group having 1 to 10 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R
⁷ represents 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.

Particularly, in the case of a ketocarboxylic acid in which R ¹ and R ² form a cyclic alkyl group, a 5- or 6-membered ring of enol-γ-lactone or enol-δ-lactone is structurally exposed to light. Is desirable because it makes the compound less soluble in a developer.

The ketocarboxylic acid structure represented by the above formula (1) or (2) is desirably contained in a film forming component constituting the above photosensitive composition. The film-forming component generally has a weight average molecular weight of 1,000 to 300,0.
Although a high molecular compound of about 00 is mentioned, it is not limited to a high molecular compound as long as it can be applied with a solvent, and may be an oligomer or a low molecular compound capable of forming a film. The number of the ketocarboxylic 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 ketocarboxylic 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 the formula (2). Carboxylic acid moiety (-COOH) and ketone moiety in
(= CO) in some cases, and the enol lactonization reaction may be difficult to occur. Equation (1)
Alternatively, when the ketocarboxylic acid structure represented by the formula (2) is included in the side chain of the polymer compound, the carboxylic acid moiety and the ketone moiety are hardly distant from each other, so that enol lactonization easily occurs. It is more desirable because it is easy to form a pattern 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 structures of adamantyl, norbornane, tricyclodecane and androstane. These structures have high dry etching resistance and are transparent in the wavelength region of far ultraviolet light, particularly ArF excimer laser light. Therefore, by including such a structure, the transmittance of exposure light during exposure is reduced. And dry etching resistance can be improved.

That is, the resist film containing the photosensitive composition is exposed and developed to form a predetermined negative pattern,
When this is used as a resist mask for dry etching, a highly reliable and stable pattern can be transferred to a substrate because of its high resistance to etching such as plasma.

As an example of a preferred polymer compound in which the ketocarboxylic acid structure represented by the above formula (1) or (2) is contained in the side chain of the polymer compound and has an alicyclic structure,
The following equations (3) and (4) are given.

[0033]

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[0034]

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Here, R represents hydrogen or a methyl group, and n represents 1 or 2. X represents, for example, a polymethacrylic acid structure or a polynorbornene structure. And
When n = 1, it is γ-ketocarboxylic acid, and when n = 2, it is δ-ketocarboxylic acid.

These structures are desirable because they can be easily synthesized from the androstane structure as described later, and because they contain an alicyclic structure derived from the androstane structure, the dry etching resistance increases.

The ketocarboxylic acid structure represented by the above formula (3) or (4) is desirably included as a film forming component of the photosensitive composition used in the pattern forming method of the present invention. As the film-forming component, a polymer compound having a weight average molecular weight of about 1,000 to 300,000 and having the above-mentioned X as a main chain can be generally mentioned. Any oligomer or low molecular compound capable of forming a film may be used.
The number of the ketocarboxylic 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 acid generator that generates an acid upon irradiation with actinic radiation during exposure include onium salts such as triphenylsulfonium triflate, dimethylphenylsulfonium triflate and dimethyl-4-hydroxynaphthyl triflate. Sulfonyloxyimides such as N-trifluoromethanesulfonyloxynaphthylimide, N-methanesulfonyloxynaphthylimide, N-trifluoromethanesulfonyloxysuccinimide, N-perfluorooctanesulfonyloxysuccinimide, and further sulfonic acid esters and the like. Examples thereof include, but are not limited to, those that generate an acid by irradiation with an actinic ray, for example, an ArF excimer laser. These acid generators may be used as a mixture 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.

The photosensitive composition used in the pattern forming method of the present invention includes, for example, 2-benzylpyridine for improving resolution, process stability and storage stability.
Basic compounds such as tripentylamine and triethanolamine, and salts such as tetramethylammonium iodide, tetrapentylammonium chloride and tetraethylphosphonium iodide may be added. These basic compounds and salts are used in an amount of 0.01 to 1 part by weight based on the acid generator used.
It is desirable to add 00 parts by weight.

In order to enhance the heat resistance of the formed pattern, hexamethoxymethylmelamine, 1,3,4,6-tetrakis is used as a crosslinking agent.
(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.

The photosensitive composition is used by dissolving it in a solvent and spin-coating it onto a predetermined 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. The ketocarboxylic acid having the structure of the formula (1) or the formula (2) may be used alone or as a mixture of two or more.

The active actinic radiation used in the exposure step of the pattern forming method of the present invention includes far ultraviolet light having a wavelength of 250 nm or less, for example, 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 exposure step of irradiating a predetermined pattern of actinic radiation, vacuum ultraviolet light such as ArF excimer laser light is usually exposed through a predetermined mask prepared in advance, or a predetermined reticle is irradiated through a reticle. Is formed and exposed. At this time, it is desirable to use a well-known 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 developing step of the present invention is preferably an aqueous solution of a tetraalkylammonium hydroxide having 1 to 5 carbon atoms. Also, a general-purpose 2.38% tetramethylammonium hydroxide aqueous solution used for developing i-line and g-line resists and KrF excimer laser resists is suitable.

The pattern forming method of the present invention preferably includes a step of heating the coating film after the exposure step of irradiating with actinic radiation and before the step of developing using an aqueous alkaline developer. By the step of heating the coating film, the acid-catalyzed reaction for producing enol lactone proceeds more efficiently.

The pattern forming method of the present invention is not only suitable for the manufacture of semiconductor devices, but also various other electronic components and the like, such as liquid crystal display devices and printed wiring boards, which require high-definition patterns. Suitable for electronic device manufacturing process. A typical application example of a resist pattern is
It is used as a mask when selectively etching the substrate, but also as a mask when implanting ions into the substrate, and further without removing the resist pattern from the substrate, for example, as a solder resist of a wiring substrate. There are various uses such as a method of positively leaving a resist pattern as an insulating film on a substrate and a method of forming a conductive pattern by imparting conductivity to a resist (photosensitive composition).

Therefore, in order to achieve the second object, in the method of manufacturing a semiconductor device of the present invention, a resist pattern is formed on a semiconductor substrate by the above-described pattern forming method of the present invention, and the resist pattern is used as a mask. And a step of etching the substrate or a step of implanting ions into the substrate.

In other words, a method of manufacturing a semiconductor device including the step of etching the above substrate will be described as an example. A step of forming a resist pattern on at least one of an insulating film and a conductive film formed on a semiconductor substrate, Selectively etching at least one of the insulating film and the conductor film using a resist pattern as a mask, wherein the step of forming the resist pattern comprises forming a pattern capable of achieving the first object. It is characterized in that it is constituted by a method.

Examples of the etching method used in the semiconductor manufacturing method of the present invention include a so-called dry etching method such as plasma etching, reactive ion etching, reactive ion etching, and reactive ion beam etching, and a wet etching method. No.

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 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.

[0053]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a synthesis example of a compound having a ketocarboxylic acid structure, which is a main component of a photosensitive composition applied to a pattern forming method of the present invention and a method of manufacturing a semiconductor device using the same, will be described.

<Synthesis Example 1> Synthesis of polymer (1d) having δ-ketocarboxylic acid structure: The polymer represented by the formula (1d) has a side chain of the formula (2) as described later.
Which further has a ketocarboxylic acid structure of the structure represented by the formula (3).

First, 9.6 g of testosterone, 11.4 g of dicyclohexylcarbodiimide and 0.53 g of 4-pyrrolidinopyridine were dissolved in 120 g of tetrahydrofuran, and 4.6 g of methacrylic acid was added dropwise thereto.

After the dropwise addition, the mixture was stirred and reacted at room temperature for about 4 hours. The precipitated salt, dicyclohexylurea, was separated by filtration, and 250 ml of diethyl ether was added to the filtrate.
The filtrate was washed twice with 100 ml of a 5% aqueous acetic acid solution, then twice with 100 ml of a 0.5N aqueous sodium hydrogen carbonate solution, and finally twice with 100 ml of water, and the solution was dried over sodium sulfate.

After drying the solution, the sodium sulfate was filtered off,
The solution was distilled off under reduced pressure. Thereafter, recrystallization was performed with ethyl acetate to obtain 8.4 g of testosterone methacrylate represented by the following formula (1a) (yield: 70%).

[0058]

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Next, 11.7 g of β-cholestanol and 4.1 g of triethylamine were dissolved in 100 ml of THF.
Under a nitrogen stream at 0 ° C., 4.2 g of T
A 20 ml solution of HF was added dropwise.

After the dropwise addition, the mixture was stirred at room temperature for several hours, and then triethylamine hydrochloride was filtered off. 200 ml of diethyl ether was added to the filtrate, and 100 ml of a 0.5N hydrochloric acid aqueous solution was added.
Washing, then 0.5N aqueous sodium hydrogen carbonate solution 1
Washing was performed twice with 00 ml and finally twice with 100 ml of water.

After the filtrate was dried over sodium sulfate, the sodium sulfate was filtered off and the solvent was distilled off under reduced pressure. Thereafter, recrystallization was performed with ethanol, and 8.2 g of the following formula (1b) was obtained.
Β-cholestanol methacrylate was obtained (yield: 60).
%).

[0062]

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Next, 5.3 g of the synthesized testosterone methacrylate [formula (1a)], β-cholestanol methacrylate [formula (1b)] were placed in a 300 ml three-necked flask equipped with a thermometer, a cooling tube, and a nitrogen inlet tube. 6.9 g, dimethyl-2,2'-azobis (isobutyrate) 0.73 g,
150 g of tetrahydrofuran was added, and the mixture was heated to reflux at 70 ° C. while introducing nitrogen to carry out polymerization for 7 hours.

After the polymerization, the solution was poured into 1000 ml of n-hexane, and the polymer was precipitated and dried to obtain 11.6 g of testosterone methacrylate-β-cholestanol methacrylate copolymer represented by the following formula (1c). 95%).

[0065]

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Further, when the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography (GPC),
Weight average molecular weight of 15,000 Number average molecular weight of 10.0
00.

Next, the double bond of the testosterone structure was converted to a δ-ketocarboxylic acid structure by subjecting the obtained polymer [shown by the formula (1c)] to Lemieux-von Rudloff oxidation.

That is, the formula (1) is placed in a 500 ml flask.
10 g of testosterone methacrylate-β-cholestanol methacrylate copolymer, 150 ml of tetrahydrofuran and 50 ml of t-butanol shown in c) were added, and 2.5 g of potassium carbonate dissolved in 30 ml of water was added thereto.

Separately, 18 g of sodium periodate was added to water 1
The resultant was dissolved in 60 ml to prepare an aqueous solution of sodium periodate, and 40 ml of the solution was added to the above polymer solution at room temperature. Subsequently, separately adjusted potassium permanganate was added.
Of 11 g dissolved in 12 ml of water, 4 ml 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 a period of about 10 minutes.
In a minute, 60 ml of the remaining aqueous solution of sodium periodate was added dropwise. When the aqueous solution of sodium periodate was added dropwise, the remaining aqueous solution of potassium permanganate was sometimes added so that the polymer solution during the reaction remained purple-red.

After the aqueous sodium periodate solution was added dropwise, the mixture was stirred at room temperature for several hours, cooled with ice, and an aqueous sodium hydrogen sulfite solution was added until the reaction solution turned yellow. 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 was added.
After performing the extraction twice, the ether solution was washed twice with 100 ml of a 5% aqueous sodium hydrogen carbonate solution.

When the ether solution was washed with an aqueous solution of sodium hydrogen carbonate, the color of the solution turned from yellow to colorless. After washing the ether solution three times with 100 ml of water, the solution was dried with 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 8.0 g of a white powdery polymer. Obtained. According to various analytical methods, the obtained polymer has a structure in which the double bond of testosterone of the formula (1c) is oxidized and ring-opened to form a δ-ketocarboxylic acid structure represented by the following formula (1d). I understood.

[0074]

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100 parts by weight of the obtained polymer (1d) 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 and baked at 100 ° C. for 2 minutes to obtain a polymer film. When the film (thickness: 400 nm) applied on the silicon substrate was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 2.38% by weight), the interference color changed and was dissolved in 2.0 seconds, and the remaining film became zero. became. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was observed 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 2> Synthesis of compound (2b) having a δ-ketocarboxylic acid structure: The compound represented by the formula (2b) is a compound having a side chain ketocarboxylic acid represented by the formula (3), as described later. Although it has a structure, it is not a high molecular compound, but it can be circularized by exposure to light and insoluble in a developer to form a pattern.

[0078] 7.1 g of testosterone was esterified using 10.4 g of dehydrocholic acid instead of methacrylic acid used in Synthesis Example 1 above, and 13.0 g of testosterone dehydrocholic acid represented by the following formula (2a) was obtained. Obtained.

[0079]

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Using 10.0 g of the obtained testosterone dehydrocholate, Lemi shown in Synthesis Example 1 was used.
Eux-von Rudloff oxidation was similarly performed, and instead of reprecipitation with diethyl ether / n-hexane, diethyl ether was distilled off and recrystallized with ethanol to obtain the following formula (2)
6.5 g of a compound having a δ-ketocarboxylic acid structure shown in b) was obtained.

[0081]

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The resulting compound (2b) is a low molecular weight compound having a molecular weight of 673. 100 parts by weight of the compound (2b) is dissolved in 700 parts by weight of cyclohexanone, and the compound having a pore size of 0.2 μm is obtained.
m, then spin-coated and dried at 80 ° C for 2 hours.
By baking for a minute, a uniform coating film could be obtained.

A film (thickness: 300) applied on a silicon substrate
nm) was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.113% by weight) and melted in 2.0 seconds while the interference color changed, and the residual film became zero. Also,
When the dissolution was examined using a dissolution rate monitor, the dissolution was found to have occurred without swelling.

When the absorption spectrum of the film coated on the lithium fluoride substrate was measured by a vacuum ultraviolet spectrometer (manufactured by ARC), the absorbance at 193 nm was 0.20 at a film thickness of 1.0 μm. It turned out to be small.

<Synthesis Example 3> Synthesis of polymer (3e) having a γ-ketocarboxylic acid structure: The compound represented by the formula (3e) is a compound having a side chain ketocarboxylic acid represented by the formula (4), as described later. It is a polymer compound having a structure.

The β-cholestanol of Synthesis Example 1 [formula (1)
b)) instead of epiandrosterone 1
Using 8.9 g, epiandrosterone methacrylate represented by the following formula (3a) was synthesized. 4.1 g of triethylamine and 4.2 g of methacrylic acid chloride were used in accordance with the amount of epiandrosterone. As a result of recrystallizing the composition with a mixed solvent of tetrahydrofuran / n-hexane, 16.5 g of epiandrosterone methacrylate was obtained (yield 70%).

[0087]

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3.6 g of pyrrolidine dried and distilled in the presence of potassium hydroxide, 15 g of epiandrosterone methacrylate of formula (3a) synthesized here, and 0.1 g of t-butylcatechol as a polymerization inhibitor were dissolved in anhydrous benzene. Then, the mixture was heated and refluxed for about 5 hours while removing water generated under a nitrogen stream. After distilling off benzene and excess pyrrolidine under reduced pressure, the residue was recrystallized with a mixed solvent of tetrahydrofuran / n-hexane to obtain 14 g of enamine represented by the following formula (3b).
Was obtained (80% yield).

[0089]

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Under a nitrogen stream, 6.8 g of ethyl bromoacetate and 0.1 g of t-butylcatechol as a polymerization inhibitor were added to 100 ml of a dry methanol solution of 14 g of the enamine represented by the formula (3b), and the mixture was refluxed for about 8 hours. After reflux, 2
0 ml of water was added, and the mixture was further refluxed for 1 hour. Thereafter, 200 ml of water was added, and the mixture was extracted with ethyl ether. After washing with water, the ether layer was dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure.
9.0 g of a methacrylate compound having a γ-ketoester structure represented by the following formula (3c) was obtained (yield: 59).
%).

[0091]

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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 methacrylate compound represented by the formula (3c) having a γ-ketoester structure, 5.5 g of β-cholestanol methacrylate represented by the formula (1b) of Synthesis Example 1, dimethyl -2,2'-
0.68 g of azobis (isobutyrate) and 150 g of tetrahydrofuran were added, and the mixture was heated under reflux at 70 ° C. while introducing nitrogen to carry out polymerization for 7 hours. After the polymerization, the solution was poured into 1000 ml of n-hexane, the polymer was precipitated and dried, and a copolymer of methacrylic acid ester compound (3c) and β-cholestanol methacrylate (1b) represented by the following formula (3d) was added to 12 0.1 g (yield 90%).

[0093]

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Further, when the molecular weight of this polymer in terms of polystyrene was determined in gel permeation chromatography (GPC) in tetrahydrofuran,
Weight average molecular weight of 12,000 Number average molecular weight of 9000
It was 0.

11 g of the obtained copolymer (3d) was dissolved in 50 ml of tetrahydrofuran, 50 ml of a 0.1N aqueous sodium hydroxide solution was further added thereto, and the mixture was heated under reflux for 3 hours. After the reflux, a 0.1N aqueous hydrochloric acid solution was gradually added to the mixture to make it weakly acidic. Ethyl acetate was added to this solution and extraction was performed twice, and the obtained organic layer was washed twice with water. After washing, the organic layer was dried over anhydrous sodium sulfate, and after drying, the solvent was distilled off under reduced pressure and concentrated.
The precipitate was reprecipitated to give 9.5 g of a white powdery polymer. The structure of the obtained polymer was found from various analytical methods to be a polymer having a γ-ketocarboxylic acid structure represented by the following formula (3e).

[0096]

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100 parts by weight of the obtained polymer (3e) was dissolved in 600 parts by weight of diacetone alcohol to obtain a polymer having a pore size of 0.
Filtered with a 2 μm filter. Spin it on, 1
Baking was performed at 00 ° C. for 2 minutes to obtain a polymer film. When the film (film thickness 450 nm) applied on the silicon substrate was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration 2.38% by weight), the interference color changed and melted in 3.0 seconds, and the remaining film became zero. became. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was observed 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 0.27 at a film thickness of 1.0 μm. It turned out to be small.

<Synthesis Example 4> Synthesis of polymer (4d) having γ-ketocarboxylic acid structure: As described later, the polymer represented by the formula (4d) has a side chain of the formula (1)
Which have the γ-ketocarboxylic acid structure shown in (1).

First, 20.7 g of 5-norbornene-2-carboxylic acid was dissolved in 40 ml of 90% formic acid.
A 0% aqueous hydrogen peroxide solution was added, and the mixture was heated at 50 ° C. for 2 hours. After heating, the solution was cooled to room temperature, made alkaline by adding an aqueous solution of sodium hydrogen carbonate, and then extracted twice with diethyl ether. After extraction, the organic layer is washed twice with water,
Dry over anhydrous sodium sulfate. After drying, the solvent was distilled off under reduced pressure, and the residue was recrystallized from ethyl acetate-hexane.
15.2 g of the lactone shown in a) was obtained (60% yield).

[0101]

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To 14 g of the obtained lactone (4a), 0.
Add 170 ml of 5N aqueous sodium hydroxide solution and heat for 30 minutes. After cooling, one drop of phenolphthalein solution is added to this solution and the excess base is neutralized with 0.6N aqueous hydrochloric acid. 0.16 g of ruthenium dioxide hydrate was added to this solution.
, Cooled to 20 ° C., stirred vigorously, and added a solution of 1.8 g of sodium iodate in 15 ml of water, the solution turned yellow.

After the precipitation of black ruthenium dioxide precipitates, the same amount of sodium periodate solution is added. This is repeated until the yellow color of the solution does not disappear, and finally the excess oxidizing agent is decomposed with 2-propanol and the reaction solution is acidified. The reaction solution was extracted five times with ethyl acetate, the extract was neutralized with anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure, and this was further recrystallized with acetone to obtain a γ-ketocarbonate represented by the following formula (4b). 13.8 g of the acid was obtained (90% yield).

[0104]

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In the same manner as in β-cholestanol methacrylate of the formula (1b) shown in Synthesis Example 1, using the synthesized γ-keto acid (4b) instead of β-cholestanol, the following formula (4c) A methacrylate having a γ-ketocarboxylic acid structure shown in (1) was synthesized (yield 70%).

[0106]

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A thermometer, a cooling pipe and a nitrogen introduction pipe were attached.
In a 0 ml three-necked flask, 2.4 g of the synthesized methacrylate (4c) having a γ-keto acid structure, 10.7 g of β-cholestanol methacrylate (1b), and dimethyl-
0.72 g of 2,2′-azobis (isobutyrate) and 150 g of tetrahydrofuran were added, and the mixture was refluxed at 70 ° C. while introducing nitrogen to carry out polymerization for 7 hours. After polymerization,
The solution was poured into 1000 ml of n-hexane, and the polymer was precipitated and dried to obtain 12.0 g of a polymer having a γ-ketocarboxylic acid structure represented by the following formula (4d) (yield: 92).
%).

[0108]

Embedded image

Further, when the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography (GPC),
Weight average molecular weight of 11,000 Number average molecular weight of 8,000
It was 0.

100 parts by weight of the obtained polymer (4d) 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 and baked at 100 ° C. for 2 minutes to obtain a polymer film. When the film (430 nm in thickness) applied on the silicon substrate was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 2.38% by weight), it melted in 2.7 seconds while the interference color changed, and the remaining film became zero. became. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was observed 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 0.22 at a film thickness of 1.0 μm, and the absorption was It turned out to be small.

[0112]

<Example 1> Formula (1d) synthesized in Synthesis Example 1
100 parts by weight of a polymer having a δ-ketocarboxylic acid structure, triphenylsulfonium triflate 2
Parts by weight, 0.01 parts by weight of 2-benzylpyridine was dissolved in 600 parts by weight of 1-methoxy-2-propanol, and filtered using a Teflon filter having a pore size of 0.20 μm,
This was used as a resist solution constituting the photosensitive composition.

The above-mentioned resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and then heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.35 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the light transmittance at a wavelength of 193 nm was 60%.

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 was dissolved in 5 seconds. Therefore, development was performed twice as long as that for 10 seconds, followed by rinsing with pure water for 15 seconds. As a result, the exposure amount was 25 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.

That is, the formation of the pattern which became insoluble in the developing solution due to the exposure can be achieved by converting the carboxyl group and ketone present in the side chain of the polymer having the δ-ketocarboxylic acid structure of the formula (1d) from the acid generator. An esterification reaction occurs in the molecule due to the generated acid, and the δ-ketocarboxylic acid structure is changed to an enol-δ-lactone structure, which is insoluble in a developing solution. It is understood that it is not due to.

This resist solution was heated at room temperature (23 ° C.).
° C) for 7 days, there was no change in sensitivity and resolution, indicating 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: CHF ₃ flow rate 35 sccm, gas pressure 10 mTorr, RF bias power 15
0 W was used. As a result, the etch rate of this resist was 1. when the commercially available novolak resin was 1.0.
18, indicating that the dry etching resistance was high.

[0120] The above resist applied on the NaCl plate was
Similarly, ArF excimer light was irradiated at 25 mJ / cm ² , and the infrared absorption spectra before and after baking after exposure were measured by FT-1720X manufactured by Perkin Elmer. As a result, 3466 caused by carboxylic acid after post-exposure bake
It was found that the peak around 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 a structure of the polymer (1d) having a δ-ketocarboxylic acid structure, and was soluble in a developing solution (alkali) 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 the δ-hydroxycarboxylic acid in the polymer was intramolecularly dehydrated and esterified to give an enol-δ-lactone structure. As a result, the exposed portion became insoluble in the alkali developing solution, and a negative pattern was formed. The mechanism of the negative conversion at this time was not a crosslinking reaction but a large decrease in the amount of the carboxylic acid due to lactonization, so that swelling was avoided and a fine pattern could be formed.

<Embodiment 2> Equation (1d) used in Embodiment 1
100 parts by weight of a compound having a δ-ketocarboxylic acid structure represented by the formula (2b) synthesized in Synthesis Example 2 instead of the polymer having a δ-ketocarboxylic acid structure shown in Chemical Formula 2, 2 parts by weight of an acid generator, and tetrapentylammonium chloride 0.0
1 part by weight was dissolved in 600 parts by weight of cyclohexanone, and filtered using a Teflon filter having a pore size of 0.20 μm,
This was used as a resist solution constituting the photosensitive composition.

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 coating, heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.30 μm. Was formed. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 65%.

Exposure was carried out through a chromium mask using an ArF excimer laser stepper in the same manner as in Example 1, followed by baking after exposure at 100 ° C. for 2 minutes. 23 ° C. tetramethylammonium hydroxide aqueous solution (0.11
(3% by weight), the unexposed portion of the film dissolved in 3.0 seconds. Therefore, the development was carried out for about 10 times, which is about three times as long as that, followed by rinsing with pure water for 10 seconds. As a result, a negative 0.19 μm line and space pattern was obtained at an exposure dose of 30 mJ / cm ² . At this time, no swelling of the pattern was observed.

The compound having a δ-ketocarboxylic acid structure represented by the formula (2b) has a molecular weight of 67 as shown in Synthesis Example 2.
3, the resist pattern after the exposure was the same as in Example 1, except that the compound having a δ-ketocarboxylic acid structure was converted from the enol-δ by the esterification reaction between a carboxyl group in the molecule and a ketone. -A lactone structure which has become insoluble in an alkaline developer.

Further, the above resist film was etched under the conditions of Example 1. 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 Formula (1) synthesized in Synthesis Example 1
100 parts by weight of the polymer having a δ-ketocarboxylic acid structure shown in d), and δ shown in the formula (2b) synthesized in Synthesis Example 2
30 parts by weight of a compound having a ketocarboxylic acid structure, 3 parts by weight of an acid generator triphenylsulfonium nonaflate,
Dissolve 0.015 parts by weight of tetramethylammonium iodide in 600 parts by weight of diacetone alcohol,
The solution was filtered using a 0 μm Teflon filter to obtain a resist solution constituting the photosensitive composition.

The resist solution described above was spin-coated on a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, and then heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.38 μm. Was formed. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 62%.

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, development was carried out for 8 seconds, twice as long, followed by rinsing with pure water for 10 seconds. As a result, at a light exposure of 28 mJ / cm ² , a negative 0.12 μm
A 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 100 ° C. for 2 minutes after exposure, 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 4.0 seconds. .

Therefore, the development was performed twice as long as that for 8 seconds, followed by rinsing with pure water for 10 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 parts by weight of the polymer having a γ-ketocarboxylic acid structure (3e) synthesized in Synthesis Example 1, 3 parts by weight of an acid generator trifluoromethanesulfonyloxysuccinimide, 1,3,4, 10 parts by weight of 6-tetrakis (methoxymethyl) glucoururil was dissolved in 600 parts by weight of diacetone alcohol, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution constituting a photosensitive composition.

On a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, the above resist solution was spin-coated, and after coating, heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.30 μm. Was formed. The absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer.
The transmittance at 93 nm was 60%.

Exposure was performed with an ArF excimer laser stepper through a phase shift mask as in the first embodiment.
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 0.12 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. 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 1.12 when the etching rate of the coating film of a commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.

Example 5 Formula (4) synthesized in Synthesis Example 4
100 parts by weight of the polymer having a γ-ketocarboxylic acid structure shown in d), 3 parts by weight of an acid generator, dimethylphenylsulfonium triflate, and 0.015 parts by weight of tetraethylphosphonium iodide were added to 600 parts by weight of 1-methoxy-2-propanol. After dissolution, the solution was filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution constituting the photosensitive composition.

On a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, the above-mentioned resist solution was spin-coated, followed by heating at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.33 μm. Was formed. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 62%.

Exposure was performed with an ArF excimer laser stepper through a phase shift mask as in the first embodiment.
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, development is performed for 2.5 times as long as 10 times.
After that, the sample was rinsed with pure water for 10 seconds. As a result, at an exposure amount of 27 mJ / cm ² , a negative 0.12 μm
A line and space pattern was obtained. At this time, no swelling of the pattern was observed.

This resist film was subjected to an acceleration voltage of 50 kV.
The exposure of the line-and-space pattern was performed using the electron beam lithography apparatus. Baking and development after exposure were performed under the same conditions as in the ArF excimer laser exposure.
At μC / cm ² , a negative 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 dry etching resistance was high.

<Embodiment 6> This embodiment shows an example in which the present invention is applied to a pattern forming step in a semiconductor device manufacturing process. Hereinafter, a specific description will be given with reference to the drawings.

FIG. 1 is a sectional view of a well-known MOS (metal-oxide-semiconductor) transistor. The transistor has a structure in which a drain current flowing between the source electrode 16 and the drain electrode 17 is controlled by a voltage applied to the gate electrode 18.

Here, the process of forming such a structure is comprised of more than a dozen processes, which can be roughly divided into a process up to the formation of the field oxide film 12 and a process up to the formation of the silicon gate 15 of polycrystalline silicon. The process can be grouped into three processes, a final process and a final process.

Here, the steps up to the formation of the first field oxide film 12 include the step of forming a resist pattern on the silicon nitride film. The process of forming the field oxide film 12 and the subsequent process of forming the silicon gate 15 will be mainly described with reference to the process chart of FIG.

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

As shown in FIG. 2A, a 50 nm oxide film 22 is formed on a p-type silicon wafer 21 and a 200 nm silicon nitride film 2 is formed thereon by plasma CVD.
3 is formed as a substrate.

As shown in FIG. 2B, a resist pattern 24 having a 0.30 μm line is formed on the substrate by the resist solution (photosensitive composition) and the pattern forming method shown in Example 3.

As shown in FIG. 2C, using the resist pattern 24 as a mask, the silicon nitride film 23 is etched by a well-known method. Perform ion implantation (illustration omitted).

After the resist 24 is stripped off as shown in FIG. 2D, as shown in FIG. 2E, a selective oxidation using the silicon nitride film 23 as a mask causes the element isolation region to have a thickness of 1.2 μm.
Of the field oxide film 25 is formed. At this time, an oxide film 25 'is also formed on the silicon nitride film 23.

Thereafter, a gate forming step and a final step were performed according to a known method. That is, as shown in FIG. 2F, after etching the silicon nitride film 23, the gate region is oxidized (not shown), and the polycrystalline silicon 26 is grown.

As shown in FIG. 2G, a resist pattern 27 of 0.12 μm line was formed on this substrate by using the resist solution (photosensitive composition) and the pattern forming method shown in Example 1. Do.

As shown in FIG. 2H, using the resist pattern 27 as a mask, the polysilicon 26 is etched by a known method to form a silicon gate 28.

Thereafter, a thin oxide film in the source and drain regions is etched in accordance with a well-known process (not shown), and then a polycrystalline silicon gate 28 and a source and a drain are formed.
Arsenic is diffused into the drain, and an oxide film is formed in the polycrystalline silicon gate and the source and drain regions. Open contacts for aluminum wiring to gate, source, drain, perform aluminum deposition and patterning,
Further, a protective film is formed, and a pad for bonding is opened. Thus, a MOS transistor as shown in FIG. 1 was formed.

Here, an example is described in which the pattern formation of the present invention is applied to the MOS transistor manufacturing process, in particular, the field oxide film forming process and the silicon gate forming process. However, the present invention is not limited to this. It goes without saying that the present invention can be applied to other semiconductor element manufacturing methods and processes.

Example 7 A semiconductor memory device was manufactured by using the pattern forming method shown in any one of Examples 1 to 5. Hereinafter, description will be made with reference to the cross-sectional process diagram shown in FIG. FIG. 3 is a cross-sectional view showing main steps of manufacturing the device.

As shown in FIG. 3A, a P-type Si semiconductor 31 is used as a substrate, and an element isolation region 32 is formed on the surface thereof by using a known element isolation technique. Next, for example, the thickness 15
A word line 33 having a structure in which polycrystalline Si having a thickness of 0 nm and SiO ₂ having a thickness of 200 nm is stacked is formed. Further, for example, SiO ₂ having a thickness of 150 nm is deposited using a chemical vapor deposition method, and is processed anisotropically. A side spacer 34 of SiO ₂ is formed on the side wall of the word line 33. Next, the n-diffusion layer 35 is formed by a usual method.

Next, as shown in FIG. 3B, a data line 36 made of polycrystalline Si, a refractory metal silicide, or a laminated film of these is formed through ordinary steps.

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, PZT,
A ferroelectric or a composite film of these is applied to form a capacitor insulating film 39. Continue with polycrystalline Si,
Refractory metal, refractory metal silicide, or Al, C
A plate electrode 40 is formed by applying a low-resistance conductor such as u.

Next, as shown in FIG. 3D, a wiring 41 is formed through a normal process. Thereafter, a memory element was manufactured through a normal wiring forming step and a passivation step.

Although only typical manufacturing steps have been described here, other normal manufacturing steps are used. Further, the present invention can be applied even if the order of each step is changed.

As is well known, the manufacture of a memory device includes a process of forming a semiconductor device on a semiconductor substrate, a process of forming a word line,
A thin film forming process such as a process of forming a conductor thin film for forming data lines, electrodes for capacitors, and a process of forming an insulating film for interlayer insulation and capacitors for insulating between wiring layers, and patterning these thin films by etching. This is performed by repeating the pattern forming process of forming a pattern.

The process of forming a thin film and selectively etching and patterning the thin film through a predetermined resist mask pattern as described above is called a lithography process. In the steps, the pattern forming method shown in any one of Examples 1 to 5 was applied to most of the steps. However, the present invention does not necessarily need to be applied to a process where it is not suitable to form a pattern with a negative resist or a process where 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, the shape of a pattern formed by lithography will be described with reference to FIG. FIG. 4 is a plan view showing a pattern arrangement of a memory portion of a typical pattern constituting a memory element manufactured in the above embodiment.

In the figure, reference numeral 42 denotes a word line (33), 43 denotes a data line (36), 44 denotes an active area, 45 denotes a storage electrode (38), and 46 denotes a pattern of an electrode extraction hole.
Also in this example, the pattern forming methods of Examples 1 to 5 of the present invention were used for all except for the 46 electrode extraction holes shown here. The present invention is used in the process using the minimum design rule other than the pattern formation shown here.

In this embodiment, a pattern forming method capable of forming a high-definition pattern having a line and space between patterns of 0.12 to 0.19 μm is applied.
A memory element manufactured by using the present invention can significantly reduce the dimension between patterns as compared with a memory element manufactured by using a conventional method, so that an element having the same structure can be reduced. Since the number of wafers that can be manufactured from one wafer increases, and the resist pattern does not swell with a developing solution, the yield is improved.

[0169]

As described in detail above, according to the present invention, the intended object of forming a negative pattern having excellent resolution performance with a resist material having a carboxylic acid can be achieved.

That is, a photosensitive composition containing a ketocarboxylic acid having a γ- or δ-ketocarboxylic acid structure as a main component is applied as a resist solution to a substrate, which is exposed to light and developed with an aqueous alkaline developer to obtain a ketocarboxylic acid. By changing the structure to an enol lactone structure, a fine pattern can be developed without swelling, and a negative resist pattern having excellent resolution performance can be realized.

Therefore, if this resist pattern is applied as a mask pattern in various lithography steps, a high-definition pattern can be easily formed on a desired substrate.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional process diagram for forming the transistor of FIG. 1, in which the pattern forming method of the present invention is applied to a process of forming a field oxide film and a silicon gate.

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

FIG. 4 is a plan view schematically showing a pattern arrangement of a memory unit in the memory device manufactured in the process of FIG. 3;

[Explanation of symbols]

 12, 25, 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 ... oxidation 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.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroshi Shiraishi 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. (Reference) 2H025 AA02 AB16 AC04 AD01 BD02 BE00 BE07 FA17 FA40 FA41

Claims (5)

[Claims] A step of forming a coating film made of a photosensitive composition on a substrate, an exposure step of selectively exposing said coating film to insolubilize an exposed region with a developing solution; Developing with a developing solution, wherein the photosensitive composition is treated with at least one kind of ketocarboxylic acid having a γ-ketocarboxylic acid structure and a δ-ketocarboxylic acid structure to generate an acid upon exposure to light. A pattern forming method comprising a photosensitive composition containing a generator. 2. The pattern forming method according to claim 1, wherein the ketocarboxylic acid contains a ketocarboxylic acid having a chemical structure represented by the following formula (1) or (2). Embedded image Embedded image Here, R ¹ in the formula represents an alkyl group having 1 to 10 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ represent hydrogen or an alkyl group having 1 to 10 carbon atoms. . 3. An exposure step of insolubilizing an exposed area with a developer by selectively exposing the coating film,
3. The pattern forming method according to claim 1, wherein the step of exposing the exposed area with a developing solution using a deep ultraviolet light having a wavelength of 250 nm or less comprises developing with an alkali developing solution. 4. A method for manufacturing a semiconductor device, wherein the step of forming a resist pattern on a semiconductor substrate is performed by the pattern forming method according to claim 1. 5. A step of forming a resist pattern on at least one of an insulating film and a conductive film formed on a semiconductor substrate, and selectively etching at least one of the insulating film and the conductive film using the resist pattern as a mask. 4. A method of manufacturing a semiconductor device, comprising the steps of: forming a resist pattern by the pattern forming method according to claim 1;