JPH11109627A - Pattern forming method and production of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a device to develop a fine pattern with an aq. alkali developer without swelling by irradiating a coating film consisting of a photosensitive comopsn. contg. a carboxylic acid structure with active chemical rays and changing the carboxylic acid structure in the irradiated part into a γ- or δ- lactone structure. SOLUTION: A coating film consisting of a photosensitive comopsn. contg. a carboxylic acid structure is formed on a substrate and irradiated with active chemical rays in a prescribed pattern drape to form a latent image. A reaction is progressed by heating the film and thereafter, the film is developed by using an aq. alkali developer so that a part or the whole of the carboxylic acid structure in the irradiated part is changed into a γ- or δ-lactone structure being a carboxylic ester structure. The carboxylic acid structure for forming the γ- or δ-lactone structure is preferably a γ- or δ-hydroxycarboxylic acid structure.

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 shorter wavelength light source 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 and a semiconductor device manufacturing method.

[0002]

2. Description of the Related Art A photolithography technique for forming a fine pattern on the order of microns or submicrons in an electronic device such as a semiconductor has played a central role in mass production fine processing technology. The recent demand for higher integration and higher density of semiconductor devices is
Many advances have been made in microfabrication technology. In particular, as the minimum processing size approaches the exposure wavelength, photolithography technology using a KrF excimer laser (248 nm) from g-line (436 nm) and i-line (365 nm) of a high-pressure mercury lamp and a shorter wavelength light source is developed. It has been. In response to these changes in the exposure wavelength, materials corresponding to the respective wavelengths of the photoresist have been developed. Conventionally, photoresists suitable for these wavelengths have different photosensitizers or photosensitive mechanisms, but aqueous alkali development utilizing the aqueous alkali solubility of a resin or a polymer material having a phenol structure has been industrially used. Was. These resins or polymer materials inevitably contain a large amount of aromatic rings, which was also a chemical structural element for improving the etching resistance in a dry etching step after the formation of a resist pattern.

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

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

On the other hand, various resist materials having high transmittance in this wavelength region and high dry etching resistance have been proposed. ArF excimer laser wavelength 19
The use of an adamantane skeleton as a chemical structure that is transparent in the far ultraviolet region including 3 nm and can impart dry etching resistance to a resist material instead of an aromatic ring is disclosed in Japanese Patent Application Laid-Open No. 4-396.
65, JP-A-5-265212, and JP-A-5-80515 and JP-A-5-257.
284. In addition to these structures,
It is disclosed in JP-A-7-28237 and JP-A-8-259626 that general alicyclic structures such as tricyclodecanyl groups are effective.
Is disclosed.

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

[0007]

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 than a resin having a carboxylic acid structure, 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, 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.

It is generally known that a carboxylic acid is converted into a carboxylic ester by an acid-catalyzed reaction with an alcohol in a solution, and this reaction is one of useful methods for synthesizing a carboxylic ester. . However, since this reaction is an equilibrium reaction, in order to advance the reaction to the ester side, it is necessary to use a large excess of alcohol and further take out by-product water out of the system. When this reaction is applied to a radiation-sensitive composition, a large excess of alcohol cannot be added while maintaining the alkali solubility of the coating film, and it is difficult to remove water generated by the reaction from the system. Therefore, esterification usually proceeds only by a few percent. As a result, the first object of the present invention was that there was a drawback that the reduction of the amount of the carboxylic acid alone did not provide a dissolution contrast sufficient to form a pattern. It is an object of the present invention to provide a method for forming a negative pattern having excellent resolution performance by using esterification of a resin having a carboxylic acid, which can be developed without performing development. A second object of the present invention is to provide a method for manufacturing a semiconductor device using such a pattern forming method.

[0010]

Means for Solving the Problems In order to achieve the first object, a pattern forming method of the present invention forms a coating film comprising a photosensitive composition containing at least a carboxylic acid structure on a predetermined substrate. By irradiating the coating film with actinic radiation in a predetermined pattern to form a latent image of a desired pattern in the coating film, heating the film to cause a reaction to proceed, and then applying an aqueous alkaline developer In the pattern forming method of developing a desired pattern in the coating film using the above, a part or all of the carboxylic acid structure of the irradiated portion of the active radiation is changed to a γ-lactone structure or a δ-lactone structure which is a carboxylic acid ester structure. It is something that depends.

[0011] The structure of these γ-lactone and δ-lactone structures is such that an alcohol which is a carboxylic acid esterification partner is formed from a compound having a carboxylic acid in the γ-position or δ-position in the molecule. Esterification by reaction occurs more easily than usual. Further, the produced ester is not hydrolyzed by a commonly used aqueous solution of tetraalkylammonium hydroxide and is stable during development.

The γ-lactone structure or δ-
As the structure of the carboxylic acid for producing the lactone structure, a γ-hydroxycarboxylic acid structure or a δ-hydroxycarboxylic acid structure is desirable. In such a structure, a five-membered or six-membered ring can be formed by intramolecular esterification by an acid-catalyzed reaction, so that esterification occurs easily.

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

[0014]

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[0015]

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Wherein R1, R2, R3, R4, R5, R6, R
7, R8 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.

Further, it is desirable that at least the carboxylic acid structure represented by the above formula (1) or (2) is contained in the polymer compound constituting the photosensitive composition.

Specifically, the resin containing at least a repeating structure selected from the following general formulas (5) to (12) has the above-mentioned structure, has a small absorption in the far ultraviolet region, and has a dry etch. It is desirable because it has resistance.

[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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Here, n in the formulas represents an integer.

The resin having at least the repeating structure represented by the above formula (5) or (6) contains a cyclic aliphatic hydrocarbon skeleton such as 5-methylenebicyclo [2.2.1] hept-2-ene. It can be obtained by subjecting a compound and maleic anhydride to a radical copolymer, reducing the maleic anhydride portion to form a lactone, and hydrolyzing and modifying it.

The resin having at least the repeating structure represented by the above formula (7) or (8) is cycloocta-
A radical copolymer of a compound containing a cyclic aliphatic hydrocarbon skeleton such as 1,5-diene and maleic anhydride is reduced, the maleic anhydride portion is reduced to lactone, which is further hydrolyzed and modified. It can be obtained by:

The resin having at least the repeating structure represented by the above formula (9) or (10) has a cyclic aliphatic hydrocarbon skeleton such as 5-ethylenebicyclo [2.2.1] hept-2-ene. It can be obtained by subjecting a compound containing the compound and maleic anhydride to a radical copolymer, reducing the maleic anhydride portion to a lactone, and further hydrolyzing and modifying it.

The resin having at least a repeating structure represented by the above formula (11) or (12) has a cyclic aliphatic hydrocarbon skeleton such as 5-vinylbicyclo [2.2.1] hept-2-ene. It can be obtained by subjecting a compound containing the compound and maleic anhydride to a radical copolymer, reducing the maleic anhydride portion to a lactone, and further hydrolyzing and modifying it.

The weight average molecular weight of these resins is
It is desirable to be 1,000 to 300,000.

Among the above-mentioned polymer compounds, those containing a repeating alicyclic structure having a carboxylic acid structure represented by the above formula (1) or (2) in the side chain are directly substituted with (1) in the main chain.
Alternatively, lactonization in an acid-catalyzed reaction is more likely to occur and higher sensitivity is more likely to be obtained, as compared with those containing a carboxylic acid structure represented by (2), and this is more preferable.

Specifically, the above formula (5) or (6) or (9) or (10) or (11) or (12)
A resin containing a repeating alicyclic structure having a carboxylic acid structure represented by the above formula (1) or (2) in the side chain, represented by the following formula, is represented by the above formula (7) or (8). A resin having a carboxylic acid structure represented by (1) or (2) directly in the main chain, as shown, is more preferable because a pattern can be formed with higher sensitivity.

When the carboxylic acid structure represented by the formula (1) or (2) is directly contained in the main chain, the carboxylic acid portion in the formula (1) or (2) is sterically far from the hydroxyl group. In some cases, the lactonization reaction does not easily occur. On the other hand, when the carboxylic acid structure represented by the formula (1) or (2) is included in a side chain, the carboxylic acid portion and the hydroxyl group portion are hardly distant from each other three-dimensionally.
Lactonization is likely to occur easily and pattern formation may be performed with high sensitivity.

The resin having the structure described above becomes a pattern-forming material by combining a compound capable of generating an acid upon irradiation with actinic radiation with 0.1 to 30 parts by weight of the resin. Examples of the compound that generates an acid upon irradiation with active actinic radiation include onium salts such as triphenylsulfonium triflate, sulfonyloxyimides such as trifluoromethanesulfonyloxynaphthylimide, and sulfonic acid esters. For example, any material that generates an acid by irradiation with an ArF excimer laser or the like may be used.

The carboxylic acid structure used in the pattern forming method of the present invention may be a chemical structure represented by the following formula (3) or (4).

[0038]

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[0039]

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Wherein R1, R2, R3, R4, R5, R6, R
7, R8 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. In the formula, X represents an acetal or ketal such as a 1-ethoxyethyl group or a tetrahydropyranyl group. In this case, since the hydroxyl group is protected by X, it is more thermally stable.

Further, at least the carboxylic acid structure represented by the above formula (3) or (4) is desirably contained in the polymer compound constituting the photosensitive composition.

Among the above-mentioned polymer compounds, those containing a repeating alicyclic structure having a carboxylic acid structure represented by the above formula (3) or (4) in the side chain are directly substituted with (3) or (3) in the main chain. It is more preferable because the lactonization in the acid-catalyzed reaction easily occurs and the sensitivity tends to be high, as compared with those containing a carboxylic acid structure represented by (4).

When the carboxylic acid structure represented by the formula (3) or (4) is directly contained in the main chain, the carboxylic acid moiety in the formula (3) or (4) is sterically substituted with the protected hydroxyl group. May be distant, and the lactonization reaction may not easily occur. Equation (3) or (4)
When the carboxylic acid structure represented by is included in the side chain,
Since the carboxylic acid portion and the protected hydroxyl group portion are hardly distant in three dimensions, lactonization can easily occur and pattern formation with high sensitivity may be possible.

The photosensitive composition containing a carboxylic acid structure used in the pattern forming method of the present invention may further contain an alicyclic structure for improving dry etching resistance. Examples of the alicyclic structure include adamantyl, norbornane, tricyclodecane and androstane structures. These structures are transparent in the far ultraviolet region and have dry etching resistance.

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

The aqueous alkaline developer used in the present invention is preferably an aqueous solution of tetraalkylammonium hydroxide having 1 to 5 carbon atoms.

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

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

The substrate processed in the method of manufacturing a semiconductor device according to the present invention may be 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.

In the present invention, the carboxylic acid is converted into a carboxylic acid ester efficiently by utilizing a highly reactive lactonization among the esterifications of the carboxylic acid by a catalytic reaction using an acid generated by exposure. be able to. Since this reaction is intramolecular esterification, cross-linking between molecules does not occur, and the amount of the carboxylic acid simply changes between the exposed portion and the unexposed portion. If the carboxylic acid and the alcohol are separate molecules, only a few percent of the carboxylic acid is esterified in the membrane by the acid-catalyzed reaction under practically applicable conditions. On the other hand, in the γ- or δ-lactonization used in the pattern forming method of the present invention, in the exposed area,
0% or more of the carboxylic acids are esterified. As a result, the dissolution rate greatly changes, and no cross-linking reaction occurs, so that swelling, which is a problem of the prior art, can be avoided, and a fine pattern can be formed.

[0051]

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

<Synthesis Example 1> Synthesis of polymer (1b) having γ-hydroxycarboxylic acid structure 5-Methylenebicyclo [2.2.1] was placed in a 500 ml three-necked flask equipped with a thermometer, a cooling tube and a nitrogen inlet tube. ] Hept-2-ene 21.2 g, maleic anhydride 19.6 g,
2,2'-azobis (isobutyronitrile) 2.56
g and 240 g of tetrahydrofuran, and heated to reflux at 70 ° C. while introducing nitrogen to carry out polymerization for 8 hours. After the polymerization, the solution was poured into 1000 ml of n-hexane, and the polymer was precipitated and dried, followed by drying with 5-methylenebicyclo [2.2.
1] Hept-2-ene-maleic anhydride copolymer (1
37.5 g of a) were obtained (92% yield). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0053]

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In the formula, n represents an integer.

When the molecular weight of this polymer in tetrahydrofuran was determined by gel permeation chromatography (GPC), the weight average molecular weight was 5,800 and the number average molecular weight was 2,500.
Met.

1.9 g of sodium borohydride and 30 g of tetrahydrofuran were placed in a 500 ml three-necked flask, cooled to 0 ° C. in an ice bath under nitrogen and stirred, and the 5-methylenebicyclo [2.
2.1] Hept-2-ene-maleic anhydride copolymer 1
A solution obtained by dissolving 0 g in 100 g of tetrahydrofuran was dropped over about 1 hour. After the dropwise addition, the mixture was stirred for several hours and left overnight.

After the solution was poured into about 300 ml of water and stirred, about 1N aqueous hydrochloric acid was gradually added to the solution to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution and extraction was performed twice, and the obtained organic layer was washed twice with 100 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate. After drying, the solvent was distilled off under reduced pressure to reduce the amount. The resulting solution was poured into 500 ml of n-hexane, and the precipitated polymer was dried to obtain 7.8 g of a white powdery polymer. Was. According to various analytical methods, the obtained polymer has a structure in which the anhydride portion of (1a) is reduced to a lactone and a polymer (1b) having at least a ring-opened γ-hydroxycarboxylic acid structure obtained by various analysis methods. I found it.

[0058]

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Or

[0060]

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In the formula, l and m represent integers.

100 parts by weight of the obtained polymer (1b) was dissolved in 600 parts by weight of cyclohexanone, and the pore size was 0.2 μm.
m. Spin it on, 100
Baking was performed at 2 ° C. for 2 minutes to obtain a polymer film. A film (570 nm thick) applied on a silicon substrate is coated with a tetramethylammonium hydroxide aqueous solution (concentration: 0.113% by weight).
When it was immersed in, it melted in 7.2 seconds while the interference color changed, and the residual film became zero. When dissolution was examined using a dissolution rate monitor, it was found that the dissolution was observed without swelling. FIG. 1 shows the relationship between the development time, which is raw data obtained using a dissolution rate monitor, and the intensity of monitor light.
FIG. 2 shows the relationship between the dissolution time and the film thickness obtained by analyzing the results.

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 0.80 at a film thickness of 1.0 μm. It turned out to be small.

<Synthesis Example 2> Synthesis of Polymer (2b) Having γ-Hydroxycarboxylic Acid Structure Instead of 21.2 g of 5-methylenebicyclo [2.2.1] hept-2-ene used in Synthesis Example 1, , Cycloocta
Radical polymerization was similarly performed using 21.6 g of 1,5-diene to obtain 38 g of cycloocta-1,5-diene-maleic anhydride copolymer (2a) (yield: 93%). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0065]

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In the formula, n represents an integer.

The molecular weight of this polymer in terms of polystyrene was such that the weight average molecular weight was 1,400, the number average molecular weight was 1,
000.

When the anhydrous portion was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1,
The structure of the obtained polymer was determined from various analytical methods (2a)
Was found to be a polymer (2b) having at least a structure in which the anhydride portion was reduced and lactonized, and a further opened γ-hydroxycarboxylic acid structure.

[0069]

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Or

[0071]

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In the formula, l and m represent an integer.

<Synthesis Example 3> Synthesis of polymer (3b) having a γ-hydroxycarboxylic acid structure In place of 21.2 g of 5-methylenebicyclo [2.2.1] hept-2-ene used in Synthesis Example 1, Similarly, radical polymerization was carried out using 24 g of 5-ethylenebicyclo [2.2.1] hept-2-ene to give 5-ethylenebicyclo [2.
2.1] 37 g of hept-2-ene-maleic anhydride copolymer (3a) was obtained (yield 86%). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0074]

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In the formula, n represents an integer.

The molecular weight of this polymer in terms of polystyrene was such that the weight average molecular weight was 3,300, the number average molecular weight was 2,
000.

The anhydride was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1.
The structure of the obtained polymer was determined by various analytical methods (3a)
Was found to be a polymer (3b) having a structure in which the anhydride portion was reduced and lactonized, and a polymer having at least a ring-opened γ-hydroxycarboxylic acid structure.

[0078]

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Or

[0080]

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In the formula, l and m represent integers.

<Synthesis Example 4> Synthesis of polymer (4b) having a γ-hydroxycarboxylic acid structure In place of 21.2 g of 5-methylenebicyclo [2.2.1] hept-2-ene used in Synthesis Example 1 , 5-vinylbicyclo [2.2.1] hept-2-ene was similarly subjected to radical polymerization to give 5-vinylbicyclo [2.2.
1] Hept-2-ene-maleic anhydride copolymer (4
26 g of a) were obtained (59% yield). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0083]

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In the formula, n represents an integer.

The molecular weight of this polymer in terms of polystyrene was such that the weight average molecular weight was 2,900, the number average molecular weight was 1,
700.

When the anhydrous portion was reduced and hydrolyzed with sodium borohydride in the same manner as in Synthesis Example 1,
The structure of the obtained polymer was determined by various analytical methods (4a)
Was found to be a polymer (4b) having at least a structure in which an anhydride portion was reduced and lactonized, and a polymer having at least a ring-opened γ-hydroxycarboxylic acid structure.

[0087]

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Or

[0089]

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In the formula, l and m represent integers.

<Synthesis Example 5> (5-1) Synthesis of lithocholic acid dimer (5a) Lithocholic acid 1 was placed in a 300 ml three-necked flask under a nitrogen stream.
1.3 g (0.030 mol), pyridine 2.4 g
(0.030 mol) and 100 m of tetrahydrofuran
1 while cooling to 0 ° C.
2.3 g of succinyl chloride dissolved in 0 ml (0.0 g
15 mol) was added dropwise. After dropping, the mixture is stirred at room temperature for 2 hours,
It was refluxed for another 2 hours. After the reflux, the precipitated black salt was filtered off, and the solution was added dropwise to 1000 ml of a 1% aqueous hydrochloric acid solution. The deposited gray precipitate was filtered by suction, washed with water, and dried to obtain 12.6 g of lithocholic acid dimer (5a).

[0092]

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Here, lithocholic acid was used as the alicyclic compound having a carboxylic acid, but deoxycholic acid, cholic acid, ursodeoxycholic acid and the like can also be used. However, since these have a plurality of alcoholic hydroxyl groups in the molecule, an oligomer is generated instead of a dimer in the reaction with dicarboxylic acid chloride. In addition, dicarboxylic acid chloride is not only succinyl chloride, but also malonic chloride, 1,3-
Any material such as adamantane dicarboxylic acid chloride can be used.

(5-2) 1- (tetrahydropyranyloxy) -2-bromoethane (5b) and 1- (tetrahydropyranyloxy) -3-bromopropane (5c)
Synthesis of 2-bromoethanol 12.5 g (0.10 mol),
12.6 g (0.15 g) of 3,4-dihydro-2H-pyran
mol) was dissolved in 200 ml of ethyl acetate, and 1.0 g of pyridinium-p-toluenesulfonate was added thereto, followed by stirring at room temperature for 4 hours. After confirming the disappearance of the alcoholic hydroxyl group in the infrared absorption spectrum,
Tetramethylammonium hydroxide 2.38 was added to the solution.
80% aqueous solution, and washed twice.
Washed twice with ml. The organic layer was dried over sodium sulfate and distilled under reduced pressure to obtain 15.7 g of 1- (tetrahydropyranyloxy) -2-bromoethane (5b).

[0095]

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Further, 1- (tetrahydropyranyloxy) -3-bromopropane (5c) was synthesized in the same manner.

[0097]

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(5-3) Synthesis of compound (5d) having a γ-hydroxycarboxylic acid structure and compound (5e) having a δ-hydroxycarboxylic acid structure Lithium diisopropylamide 2.0 in a stream of dry nitrogen.
100 ml of dry tetrahydrofuran was added to 30 ml (0.060 mol) of the M solution (commercial product), and 11.7 g (0.014 mol) of the synthesized lithocholic acid dimer (5a) was added thereto.
mol) of dry tetrahydrofuran solution at a reaction temperature of 0
The mixture was added dropwise so as not to exceed 0 ° C and stirred at 0 ° C. 5.4 g of hexamethylphosphoric triamide (0.030
mol), and the mixture was stirred at 0 ° C, and then synthesized 1- (tetrahydropyranyloxy) -2-bromoethane (5
b) 15.7 g were added quickly at 0 ° C. Although the temperature rose, the mixture was left at room temperature for 2 hours while stirring.
200 to 300 ml of an ice-cooled 5% hydrochloric acid aqueous solution was added to confirm weak acidity.
Extracted times. Thereafter, the organic layer was washed with a 3% hydrochloric acid aqueous solution 100 m.
The organic layer was washed with 100 ml of water, washed twice with 100 ml of water, and dried over sodium sulfate. After drying, the solvent was distilled off under reduced pressure, concentrated, and reprecipitated with hexane to obtain 12.1 g of a compound (5d) having a γ-hydroxycarboxylic acid structure. From various analyses, the product was found to have the following structure with some tetrahydropyranyl groups remaining.

[0099]

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In the formula, R represents hydrogen or a tetrahydropyranyl group.

Similarly, 1- (tetrahydropyranyloxy) -2-bromoethane (5b) used above was used.
, Using an equimolar amount thereof to 1- (tetrahydropyranyloxy) -3-bromopropane (5c).
A compound (5e) having a -hydroxycarboxylic acid structure was obtained. From various analyses, the product was found to have the following structure with some tetrahydropyranyl groups remaining.

[0102]

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In the formula, R represents hydrogen or a tetrahydropyranyl group.

Example 1 Polymer (1b) 100 having a γ-hydroxycarboxylic acid structure synthesized in Synthesis Example 1
Parts by weight, 2 parts by weight of an acid generator triphenylsulfonium triflate are dissolved in 600 parts by weight of cyclohexanone,
The solution was 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 then heated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.54 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 25%.

The substrate coated with the above-described resist was placed in an exposure experiment apparatus in which the inside of the apparatus was replaced with nitrogen, and a Levenson type phase shift mask formed on a quartz plate was adhered thereon. The mask was irradiated with ArF excimer laser light through the mask, and then baked after exposure at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C., the unexposed portion of the film was dissolved in 30 seconds. So the development
The cleaning was performed four times as long as 120 seconds, and then rinsed with pure water for 60 seconds. As a result, at an exposure amount of 20 mJ / cm2,
A negative 0.20 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

At this time, the obtained substrate with the pattern was
When immersed in tetrahydrofuran, the pattern was instantaneously dissolved, and it was found that no cross-linking had occurred.

The resist film was exposed through a Levenson-type phase shift mask using a KrF excimer laser stepper (NA = 0.45). After that, when post-exposure bake and development were performed under the above process conditions, an exposure of 30 mJ / cm 2 and a negative 0.
An 18 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

Further, the above-mentioned resist film (film thickness 540 nm) applied on the aluminum substrate was etched by an ECR dry etching apparatus under the following conditions.

Cl 2 flow rate 90 sccm BCl 3 flow rate 60 sccm Gas pressure 1.3 Pa RF bias power 140 W As a result, the etch rate of this resist is 1230 nm
/ Min. The etch rate of poly (methyl methacrylate) compared under the same conditions was smaller than 1580 nm / min.

[0111] The above resist applied on the NaCl plate is
Similarly, irradiation with ArF excimer light was performed at 20 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, it was found that the peak at 3300 cm -1 due to the carboxylic acid and the hydroxyl group was significantly reduced after the post-exposure bake. It was also found that the peak at 1705 cm -1 of carboxylic acid decreased and the peak at 1770 cm -1 due to lactone increased. From the intensity of these absorptions, about 72% of the carboxylic acids before exposure were
It was found that lactonization occurred after exposure.

The resist film initially had the structure of the polymer (1b) having a γ-hydroxycarboxylic 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, the structure of γ-hydroxycarboxylic acid in the polymer was intramolecularly dehydrated and esterified using the acid as a catalyst to give a γ-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 the lactonization, so that swelling was avoided and a fine pattern could be formed.

Example 2 In place of the polymer (1b) having a γ-hydroxycarboxylic acid structure used in Example 1, 100 parts by weight of the polymer (2b) synthesized in Synthesis Example 2 was synthesized in Synthesis Example 5. 30 parts by weight of the obtained compound (5d) having a γ-hydroxycarboxylic acid structure and 2 parts by weight of an acid generator, trifluoromethanesulfonyloxynaphthylimide, were dissolved in 600 parts by weight of cyclohexanone, and the pore size was 0.20.
The solution was filtered using a μm 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 coating, heat-treated at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.52 μm. Was formed. The absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer.
The transmittance at 93 nm was 60%.

An ArF excimer laser beam is irradiated through a phase shift mask in the same manner as in the first embodiment.
A bake was performed after exposure for one minute. When the resist film was immersed in an aqueous solution of tetrabutylammonium hydroxide (0.40% by weight) at 23 ° C., the unexposed portion of the film dissolved in 15 seconds. Therefore, development is performed for 60 seconds, which is 4 times the time,
Subsequently, it was rinsed with pure water for 60 seconds. As a result, the exposure amount 2
At 7 mJ / cm 2, a negative 0.22 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

Further, the above resist film (520 nm in thickness) applied on the aluminum substrate was etched by the dry etching apparatus of the ECR system under the conditions of Example 1.

As a result, the etch rate of this resist was 1090 nm / min. The etch rate of polyhydroxystyrene compared under the same conditions was about the same as 1080 nm / min.

Example 3 100 g of the polymer (1b) having a γ-hydroxycarboxylic acid structure used in Example 1 was used.
30 parts by weight of the compound having the δ-hydroxycarboxylic acid structure (5e) synthesized in Synthesis Example 5 and 3 parts by weight of the acid generator dimethylphenylsulfonium triflate were dissolved in 600 parts by weight of cyclohexanone, and the pore size was 0.20 μm.
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 then heated at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.54 μm. Was formed. The absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer.
The transmittance at 93 nm was 65%.

An ArF excimer laser beam is irradiated through a phase shift mask in the same manner as in the first embodiment.
A bake was performed after exposure for one minute. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C., the unexposed portion of the film was dissolved in 12 seconds. Therefore, the development was performed for 48 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds. As a result, a negative 0.22 μm line and space pattern was obtained at an exposure dose of 35 mJ / cm 2. At this time, no swelling of the pattern was observed.

Further, the above-mentioned resist film (film thickness 540 nm) applied on the aluminum substrate was etched by an ECR dry etching apparatus under the conditions of Example 1.

As a result, the etch rate of this resist was 1075 nm / min. The etch rate of polyhydroxystyrene compared under the same conditions was about the same as 1080 nm / min.

<Example 4> Instead of the polymer (1b) having a γ-hydroxycarboxylic acid structure used in Example 1, 100% of the polymer (3b) having a γ-hydroxycarboxylic acid structure synthesized in Synthesis Example 3 was used. 3 parts by weight of the acid generator diphenyliodonium triflate were dissolved in 600 parts by weight of cyclohexanone, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution.

The resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane in the same manner as in Example 1, and then heated at 90 ° C. for 2 minutes to form a resist film having a thickness of 0.55 μm. Was formed.

This was exposed to a line and space pattern using an electron beam lithography apparatus with an acceleration voltage of 50 kV. After exposure baking was performed at 90 ° C. for 2 minutes, a tetramethylammonium hydroxide aqueous solution (0.1
(13% by weight), the unexposed portion of the film dissolved in 20 seconds. Therefore, the development was performed four times as long as 80 seconds, followed by rinsing with pure water for 60 seconds.
As a result, at an exposure of 15 μC / cm 2, a negative 0.2
A 0 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

<Example 5> Instead of the polymer (1b) having a γ-hydroxycarboxylic acid structure used in Example 1, 100% of the polymer (4b) having a γ-hydroxycarboxylic acid structure synthesized in Synthesis Example 4 was used. 5 parts by weight of an acid generator, camphorsulfonyloxynaphthylimide, are dissolved in 600 parts by weight of cyclohexanone, and the pore size is 0.20 μm.
Then, the solution was filtered with a Teflon filter of m 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 0.52 μm. Was formed.

This resist film was exposed through a Levenson-type phase shift mask using a KrF excimer laser stepper (NA = 0.45). After baking at 90 ° C. for 2 minutes after exposure, an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C.
When the resist film was immersed in the film, the unexposed portion of the film was dissolved in 25 seconds. Therefore, the development was performed for 100 seconds, which is four times longer than that, followed by rinsing with pure water for 60 seconds. as a result,
At an exposure dose of 20 mJ / cm 2, a negative 0.18 μm line and space pattern was obtained. At this time, no swelling of the pattern was observed.

Embodiment 7 FIG. 3 shows a known MOS (metal-
1 shows a cross-sectional view of an (oxide-semiconductor) transistor. The same transistor operates according to a voltage applied to the gate electrode 38.
The structure is such that the drain current flowing between the source electrode 36 and the drain electrode 37 is controlled.

Here, the process of fabricating such a structure is comprised of more than a dozen processes, which can be roughly divided into three processes: a process up to the formation of a field oxide film, a process up to the formation of a gate, and a final process. You can do it. Here, the steps up to the first field oxide film formation (FIG. 4) include a step of forming a resist pattern on the silicon nitride film. This field oxide film was formed as in the following examples.

As shown in FIG. 4A, a 50 nm oxide film 42 is formed on a p-type silicon wafer 41 by a known method, and a 200 nm silicon nitride film is formed thereon by plasma CVD to form a substrate. . Example 1
A resist pattern 44 of 0.50 μm line is formed by the materials and methods shown in FIG. 4 (FIG. 4B). After the silicon nitride film is etched by a known method using the resist pattern as a mask (FIG. 4C), boron ions for channel stopper are implanted using the resist as a mask again. After removing the resist (Fig. 4
(D)) A 1.2 μm field oxide film is formed in the element isolation region by selective oxidation using the silicon nitride film as a mask (FIG. 4E).

Thereafter, a gate forming step and a final step were performed according to a known method. After etching the silicon nitride film, the gate is oxidized to grow polycrystalline silicon (FIG. 4F). A resist pattern of 0.20 μm line is formed on this substrate by using the pattern forming method described in the first embodiment (FIG. 4G). Using this resist pattern as a mask, the polysilicon is etched by a known method to form a gate (FIG. 4H). Source,
The thin oxide film of the drain is etched, and then arsenic is diffused in the polysilicon gate, source and drain, and an oxide film is formed in the polysilicon gate, source and drain regions. The contacts for aluminum wiring to the gate, source, and drain are viewed from the opening, aluminum coating and patterning are performed, a protective film is formed, and pads for bonding are opened. Thus, a MOS transistor as shown in FIG. 3 is formed.

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

Comparative Example 1 10 g of the 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer synthesized in Synthesis Example 1 was treated with 150 ml of methanol and 4 ml of hydrochloric acid.
The mixture was refluxed with the droplets for about 10 hours. Initially, the polymer was insoluble in methanol, but dissolved by heating reflux and became uniform. Then, after methanol was distilled off under reduced pressure,
It was redissolved in tetrahydrofuran and reprecipitated in n-hexane to obtain 10.6 g of a white powdery polymer (1c). The structure of the obtained polymer was found to be mainly the following structure containing carboxylic acid and carboxylic acid methyl ester from various analytical methods.

[0135]

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Or

[0137]

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In the formula, n represents an integer.

100 parts by weight of the polymer (1c), 1-
30 parts by weight of hydroxymethyl adamantane and 3 parts by weight of the acid generator triphenylsulfonium triflate were dissolved in 600 parts by weight of cyclohexanone, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution.

On a silicon substrate treated with hexamethyldisilazane, the above-mentioned resist solution was spin-coated, and then heat-treated at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.51 μm.

In the same manner as in Example 1, the resist film
Irradiation with rF excimer laser light was performed, followed by baking after exposure at 100 ° C. for 2 minutes, and development with an aqueous solution of tetramethylammonium hydroxide (0.113% by weight). Irradiation with an ArF excimer laser beam at an exposure dose of 300 mJ / cm 2 did not produce a pattern, and the exposed and unexposed portions of the film dissolved in 15 seconds.

The resist applied on the NaCl plate was
Similarly, an ArF excimer light is irradiated at 300 mJ / cm 2,
Infrared absorption spectra before and after exposure and after baking were measured in the same manner as in Example 1. As a result, the spectrum change before and after the exposure bake is small, and about 3
It was found that only about% esterification had occurred.

An experiment was carried out under the same conditions using the same amount of 2-adamantanol in place of the above 1-hydroxyadamantane. However, no negative reaction occurred, and the analysis by infrared absorption spectrum showed only about 3%. It was found that no esterification had occurred.

<Comparative Example 2> Polymer (1b) 100 having a γ-hydroxycarboxylic acid structure synthesized in Synthesis Example 1
3 parts by weight of triphenylsulfonium triflate and 3 parts by weight of an acid generator were dissolved in 6000 parts by weight of cyclohexanone, and filtered using a Teflon filter having a pore size of 0.20 μm to obtain a resist solution A. The above polymer (1b)
, A resist solution was prepared in the same manner using the polymer (2b) synthesized in Synthesis Example 2 to obtain a resist solution B. Further, in the same manner as in Synthesis Example 1, the 5-
Cyclo [2.2.1] hept-2-ene-anhydromaleic is obtained by using bicyclo [2.2.1] hept-2-ene instead of methylenebicyclo [2.2.1] hept-2-ene. An acid copolymer was synthesized, and it was reduced and hydrolyzed to synthesize a polymer (6a) having the following chemical formula.

[0145]

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A resist solution was prepared in the same manner using the polymer (6a) in place of the polymer (1b), and used as a resist solution C.

Here, the polymer (1
b) is a resin containing a repeating alicyclic structure having a γ-hydroxycarboxylic acid structure in the side chain, and the polymers (2b) and (6a) used in the resists B and C are directly γ-hydroxycarboxylic acid structures in the main chain. It is a resin containing a hydroxycarboxylic acid structure.

On a silicon substrate treated with hexamethyldisilazane, the above-mentioned resist solutions A, B, and C were spin-coated, and after coating, heat-treated at 100 ° C. for 2 minutes to form a film having a thickness of 0.5.
Three types of films of resists A, B and C having a thickness of 0 μm were formed.

The substrate coated with the above-described resist was put into an exposure experiment apparatus in which the inside of the apparatus was replaced with nitrogen, and irradiated with an ArF excimer laser beam while changing the exposure stepwise, and then baked after exposure at 100 ° C. for 2 minutes. Was done. 23 ° C. tetramethylammonium hydroxide aqueous solution (0.113
% By weight), the unexposed portion of the film dissolved in 20 to 30 seconds. So the development is about 4
The cleaning was performed twice as long as 120 seconds, followed by rinsing with pure water for 60 seconds.

As a result, the resist A has an exposure amount of 15 mJ.
/ Cm2, the film was negative and the remaining film thickness was almost 100%. On the other hand, the resist B had a low sensitivity, and was 80 mJ / cm 2 when the post-exposure bake was performed at 120 ° C., and became negative and the residual film thickness was about 90%. Further resist C
Then, under the condition that the post-exposure bake is 120 ° C.,
Even at mJ / cm 2, no negative conversion occurred, and a difference in sensitivity depending on the polymer structure was observed.

[0151]

According to the present invention, it is possible to develop a negative pattern with excellent resolution by using an aqueous alkali developer solution without causing swelling of the fine pattern and by esterifying a resin having a carboxylic acid.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the development time and monitor light intensity obtained using a dissolution rate monitor when a polymer coating film of Synthesis Example 1 was applied to an aqueous alkaline developer.

FIG. 2 is a graph showing a relationship between a dissolution time and a film thickness when a polymer coating film of Synthesis Example 1 is applied to an aqueous alkaline developer.

FIG. 3 is a cross-sectional view of a MOS (metal-oxide-semiconductor) transistor.

FIG. 4 is a view showing a method for forming a field oxide film and a silicon gate using the pattern forming method of the present invention.

[Explanation of symbols]

32, 45: Field oxide film, 33: Source contact, 34: Drain contact, 35: Polycrystalline silicon, 36: Source electrode, 37: Drain electrode, 38: Gate electrode, 39: Protective film, 42: Oxide film, 44 ... resist pattern, 46 ... polycrystalline silicon film, 47 ... resist pattern, 48 ... polycrystalline silicon gate.

Claims (13)

[Claims] 1. A step of forming a coating film made of a photosensitive composition containing a carboxylic acid structure on a substrate, and irradiating the coating film with actinic radiation of a predetermined pattern to form a portion of the active radiation irradiated portion. Changing the carboxylic acid structure into a γ-lactone structure or a δ-lactone structure. 2. The pattern forming method according to claim 1, wherein said carboxylic acid structure is a γ-hydroxycarboxylic acid structure or a δ-hydroxycarboxylic acid structure. 3. The pattern forming method according to claim 1, wherein the carboxylic acid structure is represented by the following formula (1) or (2):
A pattern formation method characterized by having a chemical structure represented by: Embedded image Embedded image In the formula, R1, R2, R3, R4, R5, R6, R7 and R8 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. . 4. The pattern forming method according to claim 1, wherein the carboxylic acid structure is represented by the following formula (3) or (4):
A pattern formation method characterized by having a chemical structure represented by: Embedded image Embedded image In the formula, R1, R2, R3, R4, R5, R6, R7 and R8 represent hydrogen and 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. . In the formula, X represents an acetal such as a 1-ethoxyethyl group or a tetrahydropyranyl group. 5. The pattern forming method according to claim 3, wherein the photosensitive composition contains a polymer, and at least the polymer has a carboxylic acid structure represented by the formula (1) or (2). A pattern forming method comprising: 6. The pattern forming method according to claim 5, wherein the polymer compound has a repeating alicyclic structure having a carboxylic acid structure represented by the formula (1) or (2) in a side chain. A method for forming a pattern, comprising: 7. The pattern forming method according to claim 4, wherein the photosensitive composition contains a polymer compound, and at least the polymer compound has a carboxylic acid structure represented by the formula (3) or (4). A pattern forming method comprising: 8. The pattern forming method according to claim 4, wherein the polymer compound has a repeating alicyclic structure having a carboxylic acid structure represented by the formula (3) or (4) in a side chain. A method for forming a pattern, comprising: 9. The pattern forming method according to claim 1, wherein the photosensitive composition containing a carboxylic acid structure further contains an alicyclic structure. 10. The pattern forming method according to claim 1, wherein said active actinic radiation has a wavelength of 250 nm.
A pattern forming method characterized by the following far ultraviolet light. 11. The pattern forming method according to claim 1, wherein said active actinic ray is ArF excimer laser light. 12. The pattern forming method according to claim 1, further comprising, after the step of irradiating the active actinic ray, a step of developing a pattern on the coating film using an aqueous alkaline developer. Wherein the aqueous alkaline developer is a tetraalkylammonium hydroxide aqueous solution. 13. A step of forming a resist pattern on a semiconductor substrate by the pattern forming method according to any one of claims 1 to 12, 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.