JPH10282671A - Pattern forming method and production of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a pattern excellent in resolution by using a specified high molecular material having solubility in water-based alkali at the time of developing with a water-based alkaline developer. SOLUTION: A coating film comprising a photosensitive compsn. is formed on a specified substrate, and the coating film is irradiated with active chemical rays according to a specified pattern to form a latent image of the desired pattern in the coating film. Then the desired pattern is developed in the coating film by using a water-based alkaline developer. In this method, the development in the water-based alkaline developer is carried out by using a high molecular material having the solubility of the chemical structure expressed by one of formulae I to VIII in water-based alkali, which exists in the film substantially after forming the latent image. In formulae I to VIII, R is an alkyl group such as methyl group, ethyl group and 2-propyl group, or a cyclic alkyl group such as cyclohexanethyl group, norbornanemethyl group and adamantanemethyl group, or a cyclic alkyl group having a hydroxyl group such as 4- hydroxymethyltricyclo[5.2.1.0<2.6> ]decanyl-8-methyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a microlithography process using a photosensitive composition and a method for manufacturing a semiconductor device or the like including the microlithography process.

[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 a 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. However, aqueous alkali development utilizing the aqueous alkali solubility of a resin or a polymer material having a phenolic hydroxyl group is industrially required. Has been used for 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.

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

[0005] Polymethyl methacrylate (PMMA) or the like is known as a resist polymer material having a high transmittance at a wavelength of 193 nm of an ArF excimer laser, but it cannot be used for aqueous alkali development which is industrially advantageous. Also, dry etching resistance and sensitivity are far from practicality.

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. 4-39665.
Similarly, the use of a norbornane skeleton is disclosed in JP-A-5-80515 and JP-A-5-257284. In addition to these structures, it is disclosed in Japanese Patent Application Laid-Open Publication No. H11-157572 that general alicyclic structures such as a tricyclodecanyl group are effective.
7-28237 and JP-A-8-259626.

JP-A-8-82925 states that a compound having a terpenoid skeleton such as a menthyl group is transparent in a far ultraviolet region including a wavelength of 193 nm and can impart dry etching resistance to a resist material. Japanese Patent Application Laid-Open No. 8-15865 discloses that for the same purpose, the dry etching resistance can be enhanced by mixing a substituted androstane compound with a composition using a polymer matrix which does not always have high dry etch resistance.

A polymer having a chemical structure transparent in a deep ultraviolet region including a wavelength of 193 nm of an ArF excimer laser,
Regarding a resist material which enables aqueous alkali developability, see JP-A-4-39665, JP-A-4-184345, JP-A-4-184345.
226461, as disclosed in 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 having a carboxylic acid group added to an alicyclic structure introduced into a methacrylic ester side chain. All of them enable aqueous alkali development by utilizing a carboxylic acid structure in a side chain of a vinyl polymerizable polymer such as acrylic acid or methacrylic acid ester.

Hitherto, high performance resist materials which can be developed with aqueous alkali have utilized the properties of phenolic polymers such as novolak resins which are insoluble in water and soluble in aqueous alkali. That is, when the surface of the polymer coating film having a phenolic hydroxyl group comes into contact with an aqueous alkali solution used for a developer, the hydroxyl group is ionized into a phenolate anion and eluted into the aqueous alkali solution. At this time, the developer does not substantially penetrate into the inside of the coating film that is not in contact with the developer, and the ionized surface layer is sequentially dissolved.

In a resist material utilizing this property, a pattern can be formed by providing the presence or absence of the above-mentioned aqueous alkali solubility by a chemical reaction induced by active actinic rays such as ultraviolet rays and electron beams. Since the ionized surface layer is dissolved sequentially during the development process, the residual coating portion of the resist film does not substantially penetrate the developing solution, so that deformation such as swelling due to the developing solution does not occur, and a high-resolution pattern is formed. Can be formed.

The present inventors have conducted intensive studies on the aqueous alkali solubility of various vinyl polymerizable polymers having a carboxylic acid structure in the side chain. However, it was difficult to find the dissolution characteristic of the surface layer which was sequentially eluted.

[0012]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a chemical composition which is transparent in a deep ultraviolet region including a wavelength of 193 nm of an ArF excimer laser and has a high dry etching resistance, while being resistant to an aqueous alkaline developer. Accordingly, it is an object of the present invention to provide a pattern forming method having excellent resolution performance by utilizing a polymer material having a dissolving property in which a surface layer is sequentially eluted. A second object is to provide a method for manufacturing a semiconductor device using such a pattern forming method.

[0013]

Means for Solving the Problems In order to achieve the first object, the pattern forming method of the present invention comprises forming a coating film of a photosensitive composition on a predetermined substrate, and forming the coating film on the coating film. A pattern for forming a latent image of a desired pattern in the coating film by irradiating active actinic radiation in a predetermined pattern, and then developing the desired pattern in the coating film using an aqueous alkaline developer In the formation method, the development with an aqueous alkali developer is substantially equivalent to the solubility in an aqueous alkali based on the chemical structure represented by any one of the following chemical formulas (1) to (8) in the coating film after formation of the latent image. It is as if by.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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Wherein R is a methyl group, an ethyl group, 2
Alkyl groups such as -propyl group, or cyclic alkyl groups such as cyclohexaneethyl group, norbornanemethyl group, adamantanemethyl group, or 4-hydroxymethyltricyclo [5.2.1.0 ^2,6 ] decanyl-8-
Methyl group, 1-hydroxymethylcyclohexane-4-
It represents at least one group selected from a cyclic alkyl group having a hydroxyl group such as a methyl group.

R is preferably a cyclic alkyl group or a cyclic alkyl group having a hydroxyl group, rather than a mere alkyl group, because dry etching resistance is improved. This is desirable because the absorption in the region, especially at 193 nm, is reduced.

The structure represented by the above chemical formulas (1) and (2) is
Radical copolymerization of a compound having a cyclic aliphatic hydrocarbon skeleton such as -methylenebicyclo [2.2.1] hept-2-ene and maleic anhydride, and the maleic anhydride portion is modified by esterification with an alcohol. It is obtained by doing.

The structure represented by the above chemical formulas (3) and (4) is obtained by radically copolymerizing a compound having a cyclic aliphatic hydrocarbon skeleton such as cycloocta-1,5-diene with maleic anhydride to form a copolymer thereof. It is obtained by esterifying and modifying the maleic acid moiety with an alcohol.

The structure represented by the above chemical formulas (5) and (6)
Radical copolymerization of maleic anhydride with a compound having a cyclic aliphatic hydrocarbon skeleton such as ethylenebicyclo [2.2.1] hept-2-ene, and esterification of the maleic anhydride portion with an alcohol for modification. It is obtained by doing.

The structure represented by the above chemical formulas (7) and (8)
Radical copolymerization of a compound having a cyclic aliphatic hydrocarbon skeleton such as -vinylbicyclo [2.2.1] hept-2-ene and maleic anhydride, and the maleic anhydride portion is modified by esterification with an alcohol. It is obtained by doing.

As the alcohol used for the above modification, aliphatic alcohols such as methanol, ethanol and 2-propanol are preferable, and cyclohexaneethanol, norbornanemethanol, and 1-hydroxyl-ethanol are preferable since the dry etching resistance is further improved. Cycloaliphatic alcohols such as adamantanol, or 4,8-bis (hydroxymethyl) tricyclo [5.2.1.0
^2,6 ] decane and cycloaliphatic diols such as 1,4-bis (hydroxymethyl) cyclohexane are preferred.

These compounds containing a cyclic aliphatic hydrocarbon skeleton and the aliphatic alcohol used for modifying the maleic anhydride copolymer may be used as a mixture of two or more kinds. Further, the maleic anhydride portion in the copolymer may not be completely esterified with alcohol. However, since the structure of the maleic anhydride portion has an absorption in the far ultraviolet region including 193 nm, it is preferable that the structure be modified by esterification as much as possible.

The active actinic radiation used in the pattern forming method of the present invention includes ultraviolet light, far ultraviolet light such as KrF excimer laser light, 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.

When the active actinic ray used in the pattern forming method of the present invention is an 193 nm ArF excimer laser, those having the structures of the above-mentioned chemical formulas (1) to (4) are preferable because of their smaller absorption at that wavelength. .

The pattern forming method of the present invention comprises a step of forming a latent image of a desired pattern in a coating film by irradiating actinic radiation, and a step of forming a desired pattern in the coating film using an aqueous alkaline developer. A step of heating the coating film may be included between the step of developing.

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, and reactive ion beam etching, and wet etching methods.

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

In the pattern forming method of the present invention, the development with the aqueous alkaline developer is substantially based on the chemical structure represented by the above-mentioned chemical formulas (1) to (8) in the coating film after forming the latent image. And The structure inducing the alkali developability is based on one unit of the cyclic aliphatic hydrocarbon skeleton.
It has one unit of carboxylic acid structure nearby. Therefore, it has a structure in which hydrophobic portions and hydrophilic portions are alternately arranged, or a structure in which the hydrophilicity and the hydrophobicity are well-balanced one to one.

In particular, in the structures represented by the chemical formulas (1), (2) and (5) to (8), portions of the cyclic aliphatic hydrocarbon skeleton are connected to form a polymer compound. From the carboxylic acid, and is similar to the structure of a novolak resin conventionally used. As a result, as seen in the polymer coating having a phenolic hydroxyl group, the carboxyl group on the surface is ionized upon contact with the aqueous alkali solution used for the developer and eluted into the aqueous alkali solution. At this time, the developer does not substantially penetrate into the inside of the coating film which is not in contact with the developer due to the balance of the polarity, and the ionized surface layer is sequentially dissolved.

In a resist material utilizing this property, it is possible to form a pattern by providing the presence or absence of the above-mentioned aqueous alkali solubility by a chemical reaction induced by active actinic rays such as far ultraviolet rays and electron beams. Here, since the surface layer ionized in the developing process is sequentially dissolved, the permeation of the developing solution does not substantially occur in the remaining coating portion of the resist film. Therefore, a high-resolution pattern can be formed without deformation such as swelling due to the developer.

In the chemical structures represented by the chemical formulas (1) to (8), the structure of the acid anhydride is modified by esterification, so that the alkyl group portion of the ester can further impart dry etching resistance. In addition, the dissolution rate can be controlled to some extent by the height of the portion.

[0040]

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> Norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2
-Synthesis thermometer of ene-maleic anhydride copolymer (A),
In a 500 ml three-necked flask equipped with a cooling tube and a nitrogen inlet tube, 5-methylenebicyclo [2.2.1] hept-2-
21.2 g of ene, 19.6 g of maleic anhydride, 2.56 g of 2,2'-azobis (isobutyronitrile) and 240 g of tetrahydrofuran (THF) were added, and the mixture was heated to reflux at 70 ° C. while introducing nitrogen for 8 hours. Polymerization was performed. After polymerization,
The solution was poured into 1000 ml of n-hexane to precipitate a polymer, and the polymer was dried to obtain 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (9).
7.5 g were obtained (92% yield). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

[0042]

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

This 5-methylenebicyclo [2.2.1]
10 g of a hept-2-ene-maleic anhydride copolymer was dissolved in 80 g of tetrahydrofuran to obtain norbornane-2-ene.
50 g of methanol and 6 drops of hydrochloric acid were added, and the mixture was refluxed under heating for about 30 hours. Thereafter, the solution was reprecipitated twice with n-hexane to obtain 13.8 g of a white powdery polymer (A). It was found from various analytical methods that the structure of the obtained polymer was mainly a structure of the following chemical formula (10) or (11) containing a carboxylic acid and an ester.

[0045]

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[0046]

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100 parts by weight of the obtained polymer (A) 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. When the film (480 nm in thickness) applied on the silicon substrate was immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119% by weight), the interference color changed and was dissolved in 12 seconds, and the remaining film became zero. . When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

FIG. 1 shows the relationship between the development time, which is the raw data obtained using the dissolution rate monitor, and the intensity of the 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 0.51 at a film thickness of 1.0 μm. It turned out to be small.

Further, a film (film thickness 7) applied on an aluminum substrate
70 nm) 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 was 1120 nm / s.
Under the same conditions, the etch rate of poly (methyl methacrylate) was smaller than 1580 nm / s, and was equivalent to the etch rate of poly (p-hydroxystyrene) of 1080 nm / s.

<Synthesis Example 2> Synthesis of 1-ethoxyethylated [norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer] (B) 12 g of polymer (A), 4.4 g of ethyl vinyl ether
Was dissolved in 200 ml of THF, and 0.60 g of pyridinium p-toluenesulfonate was added, followed by stirring at room temperature for several hours. After confirming the progress of the reaction by an infrared absorption spectrum, 300 ml of ethyl acetate was added, and the organic layer was washed three times with 100 ml of a saline solution. After washing, the organic layer was dried over anhydrous sodium sulfate. After drying, the solvent was distilled off under reduced pressure to reduce
The polymer was poured into hexane (600 ml), and the precipitated polymer was dried and dried with 1-ethoxyethylated [norbornane-2-methanol modified 5-methylenebicyclo [2.2.1] hept-.
8.2 g of 2-ene-maleic anhydride copolymer] (B) was obtained. The structure of the obtained polymer was found to be mainly the structure of the following chemical formula (12) or (13) from various analytical methods.

[0053]

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<Synthesis Example 3> Synthesis of methanol-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (C) 5-methylenebicyclo [2] synthesized in Synthesis Example 1 .2.
1] 14 g of hept-2-ene-maleic anhydride copolymer
Was heated to reflux with 200 ml of methanol and 6 drops of hydrochloric acid for about 10 hours. At first, the polymer was insoluble in methanol, but dissolved by heating reflux and became uniform. Thereafter, methanol was distilled off under reduced pressure, then redissolved in tetrahydrofuran and reprecipitated in n-hexane to obtain 18.5 g of a white powdery polymer (C). It was found from various analytical methods that the structure of the obtained polymer was mainly a structure of the following chemical formula (14) or (15) containing a carboxylic acid and an ester.

[0056]

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As shown in Synthesis Example 1, when the obtained polymer was used as a coating film and dipped in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119%), the interference color was changed for 12.5 seconds. And the remaining film became 0. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

When the absorption spectrum of the coating film was measured as shown in Synthesis Example 1, it was found that the absorbance at 193 nm was 0.83 at a film thickness of 1.0 μm. Further, when the film applied on the aluminum substrate was dry-etched under the same conditions as in Synthesis Example 1, the etch rate was 12
It was 80 nm / s. The etch rate of poly (methyl methacrylate) under the same conditions was 1580 nm / s, which was smaller.

Synthesis Example 4 Modified with 4,8-bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane 5
-Methylenebicyclo [2.2.1] hept-2-ene-
Synthesis of maleic anhydride copolymer] (D) In the same manner as in Synthesis Example 1, 5-methylenebicyclo was prepared using 4,8-bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane. [2.2.1] Modification of a hept-2-ene-maleic anhydride copolymer (chemical formula (9)) was performed. After the reaction, after reprecipitation with n-hexane, the polymer was reprecipitated again with diethyl ether. The structure of the obtained polymer (D) was determined by the following chemical formula (16) from various analytical methods.
Or it turned out that the structure of (17) is main.

[0061]

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[0062]

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As shown in Synthesis Example 1, when a polymer was formed into a coating film and immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119%), it melted in 25 seconds while changing the interference color, and the residual film was formed. It became 0. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

When the absorption spectrum of the coating film was measured as shown in Synthesis Example 1, it was found that the absorbance at 193 nm was 0.39 at a film thickness of 1.0 μm. Further, when the film applied on the aluminum substrate was subjected to dry etching under the same conditions as in Synthesis Example 1, the etching rate was 11
00 nm / s.

<Synthesis Example 5> Synthesis of cyclohexaneethanol-modified cycloocta-1,5-diene-maleic anhydride copolymer (E) 5-methylenebicyclo [2.2.1] used in Synthesis Example 1
Instead of 21.2 g of hept-2-ene, cycloocta-
Similarly, radical polymerization was carried out using 21.6 g of 1,5-diene to obtain 38 g of a cycloocta-1,5-diene-maleic anhydride copolymer (18) (yield: 93%). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

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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), the weight average molecular weight was 1.400 and the number average molecular weight was 1,000.

In the same manner as in Synthesis Example 1, the cycloocta-1,5-diene-maleic anhydride copolymer (18) was modified using cyclohexaneethanol. The structure of the obtained polymer (E) was determined by the following chemical formula (1) from various analyses.
It turned out that the structure of 9) or (20) is main.

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As shown in Synthesis Example 1, when a polymer was formed into a coating film and immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119%), it melted in 6.9 seconds while changing the interference color. The membrane became zero. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

When the absorption spectrum of the coating film was measured as shown in Synthesis Example 1, it was found that the absorbance at 193 nm was 0.42 at a film thickness of 1.0 μm. Further, when the film applied on the aluminum substrate was subjected to dry etching under the same conditions as in Synthesis Example 1, the etching rate was 11
70 nm / s.

<Synthesis Example 6> Synthesis of 1,4-cyclohexanedimethanol-modified 5-ethylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (F) Used in Synthesis Example 1 5-methylenebicyclo [2.2.1]
Radical polymerization was similarly performed using 24 g of 5-ethylenebicyclo [2.2.1] hept-2-ene instead of 21.2 g of hept-2-ene to obtain 5-ethylenebicyclo [2.
2.1] 37 g of hept-2-ene-maleic anhydride copolymer (21) was obtained (86% yield). Various analyzes revealed that the structure of the obtained polymer was mainly the structure of the following chemical formula.

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When the molecular weight of this polymer in terms of polystyrene was examined in gel permeation chromatography (GPC) in tetrahydrofuran, the weight average molecular weight was 3,300 and the number average molecular weight was 2,000.

In the same manner as in Synthesis Example 1, modification of 5-ethylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (29) with 1,4-cyclohexanedimethanol was carried out. went. The structure of the obtained polymer (F) was found to be mainly the structures of the following chemical formulas (22) and (23) from various analytical methods.

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As shown in Synthesis Example 1, when a polymer was formed into a coating film and immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119%), the polymer melted in 7.2 seconds while changing the interference color. The membrane became zero. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

When the absorption spectrum of the coating film was measured as shown in Synthesis Example 1, it was found that the absorbance at 193 nm was 1.43 at a film thickness of 1.0 μm. Further, when the film applied on the aluminum substrate was subjected to dry etching under the same conditions as in Synthesis Example 1, the etching rate was 11
It was 50 nm / s.

<Synthesis Example 7> 1-adamantanol-modified 5
Synthesis of -vinylbicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (G) 5-Methylenebicyclo [2.2.1] used in Synthesis Example 1
Instead of 21.2 g of hept-2-ene, 24-g of 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 (2
26 g of 4) was obtained (59% yield). The following structures were found to be the main structures of the obtained polymer from various analytical methods.

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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), the weight average molecular weight was 2,900 and the number average molecular weight was 1,700.

In the same manner as in Synthesis Example 1, the 5-vinylbicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (24) was modified using 1-adamantanol. Various analyzes revealed that the structure of the obtained polymer (G) was mainly the structure of the following chemical formula (25) or (26).

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As shown in Synthesis Example 1, when a polymer was formed into a coating film and immersed in an aqueous solution of tetramethylammonium hydroxide (concentration: 0.119%), it melted in 40 seconds while changing the interference color, and the residual film was formed. It became 0. When the dissolution was examined using a dissolution rate monitor, it was found that the dissolution was achieved without swelling.

When the absorption spectrum of the coating film was measured as shown in Synthesis Example 1, it was found that the absorbance at 193 nm was 3.11 at a film thickness of 1.0 μm. Further, when the film applied on the aluminum substrate was subjected to dry etching under the same conditions as in Synthesis Example 1, the etching rate was 11
00 nm / s.

<Example 1> 1-ethoxyethylated norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (B) synthesized in Synthesis Example 2 100 parts by weight) and 5 parts by weight of an acid generator, trimethylsulfonium 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 80 ° C. for 2 minutes to form a resist film having a thickness of 0.50 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 53%, indicating high transparency.

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 mask in which a pattern of chromium was drawn on a quartz plate was adhered to the substrate.
Irradiate ArF excimer laser light through the mask,
Thereafter, post-exposure baking was performed at 80 ° C. for 2 minutes. Development was performed using an aqueous solution of tetramethylammonium hydroxide (0.119).
% By weight) at 23 ° C. for 120 seconds, followed by rinsing with pure water for 60 seconds. As a result, when the exposure amount was 30 mJ / cm ² , only the exposed portion of the resist film was dissolved and removed in the developing solution, and a positive 0.25 μm line and space pattern was obtained.

The above resist coated on the NaCl plate was
Similarly, an ArF excimer laser beam was irradiated at 30 mJ / cm ² , and infrared absorption spectra before and after exposure and after baking after exposure were measured by FT-1720X manufactured by PerkinElmer. As a result, it was found that the 1-ethoxyethyl group was removed by the exposure, and the carboxylic acid was regenerated. It was also found that the reaction occurred 100% after the exposure, and hardly changed in the post-exposure bake. This is because trifluoromethanesulfonic acid is generated from the acid generator trimethylsulfonium triflate by ArF excimer laser exposure, and the acid is used as a catalyst to produce norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] having a carboxyl group. This shows that the structure of the hept-2-ene-maleic anhydride copolymer (A) was regenerated.

The resist film has a structure of 1-ethoxyethylated norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (B). It was insoluble. The acid generated by the exposure removes the 1-ethoxyethyl group and forms a carboxyl-containing norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2.
-An ene-maleic anhydride copolymer (A) was obtained, and the exposed portion was dissolved in an alkali developing solution to form a positive pattern.

The acid generator used here is not limited to trimethylsulfonium triflate.
Onium salts, sulfonic esters, sulfonyloxyimides, and the like which generate an acid by ArF excimer laser exposure may be used, and those having a small light absorption at 193 nm are desirable.

The carboxyl group of the polymer compound of the present invention, such as the norbornane-2-methanol-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (A) The protecting group in place of the 1-ethoxyethyl group used to render the compound not alkali-soluble may be any as long as the carboxyl group can be regenerated by an acid-catalyzed reaction, and the tetrahydropyranyl used in the following Example 2 is used. Acetal such as a group, ketal, ester such as a t-butyl group, and the like can be used.

Example 2 Using the polymer (C) synthesized in Synthesis Example 3 and using 3,4 dihydropyran instead of ethyl vinyl ether used in Synthesis Example 2, Synthesis Example 2
[Methanol-modified 5-methylenebicyclo [2.2.1] hept-
100 parts by weight of 2-ene-maleic anhydride copolymer] and 5 parts by weight of an acid generator N- (trifluoromethanesulfonyloxy) succinimide were dissolved in 600 parts by weight of cyclohexanone, and a resist solution was prepared in the same manner as in Example 1. .

On a silicon substrate treated with hexamethyldisilazane, the above-mentioned resist solution was spin-coated, followed by heating at 80 ° C. for 2 minutes to form a resist film having a thickness of 0.45 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 55%, indicating that the film was highly transparent.

An ArF excimer laser beam was irradiated through a mask in the same manner as in Example 1. Thereafter, baking was performed after exposure at 80 ° C. for 2 minutes. The development was carried out using an aqueous solution of tetramethylammonium hydroxide (0.119% by weight) at 23 ° C. for 120 minutes.
After that, the sample was rinsed with pure water for 60 seconds. As a result, when the exposure amount was 20 mJ / cm ² , only the exposed portion of the resist film was dissolved and removed in the developing solution, and the positive type 0.30 μm
A line and space pattern was obtained.

Example 3 Using the polymer (E) synthesized in Synthesis Example 5, 1-ethoxyethylated [cyclohexaneethanol-modified 5-methylenebicyclo [2.2.1] synthesized in the same manner as in Synthesis Example 2. [Hept-2-ene-maleic anhydride copolymer] 100 parts by weight and acid generator dimethylphenylsulfonium triflate 5 parts by weight were dissolved in cyclohexanone 600 parts by weight, and a resist solution was prepared in the same manner as in Example 1.

The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and heated at 80 ° C. for 2 minutes to form a resist film having a thickness of 0.47 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 48%, indicating that the film was highly transparent.

An ArF excimer laser beam was irradiated through a mask in the same manner as in Example 1. Thereafter, baking was performed after exposure at 80 ° C. for 2 minutes. The development was carried out using an aqueous solution of tetramethylammonium hydroxide (0.119% by weight) at 23 ° C. for 120 minutes.
After that, the sample was rinsed with pure water for 60 seconds. As a result, when the exposure amount was 25 mJ / cm ² , only the exposed portion of the resist film was dissolved and removed in the developing solution, and a positive 0.25 μm
A line and space pattern was obtained.

Example 4 4,8-Synthesized in Synthesis Example 4
Bis (hydroxymethyl) tricyclo [5.2.1.0
^2,6 ] decane-modified 5-methylenebicyclo [2.2.1]
Hept-2-ene-maleic anhydride copolymer (D) 10
0 parts by weight, 20 parts by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ERL-4221 manufactured by Union Carbide) and 5 parts by weight of dimethylphenylsulfonium triflate were dissolved in 600 parts by weight of cyclohexanone. Example 1
A resist solution was prepared in the same manner as described above.

The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and heated at 80 ° C. for 2 minutes to form a resist film having a thickness of 0.42 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 53%, indicating high transparency.

An ArF excimer laser beam was irradiated through a phase shift mask in the same manner as in Example 1. Thereafter, baking was performed at 100 ° C. for 2 minutes after exposure. Development was performed using an aqueous solution of tetramethylammonium hydroxide (0.119% by weight).
This was carried out at 3 ° C. for 80 seconds, followed by rinsing with pure water for 60 seconds. As a result, when the exposure amount was 250 mJ / cm ² , only the unexposed portions of the resist film were dissolved and removed in the developing solution, and a negative 0.20 μm line and space pattern was obtained.

In this resist, 4,8-bis (hydroxymethyl) tricyclo [5.
2.1.0 ^2,6 ] decane-modified 5-methylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (D) shows alkali solubility, so that the resist film is not exposed. Parts dissolve during development. On the other hand, in the exposed part, the acid generated from the acid generator dimethylphenylsulfonium triflate caused 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate at the time of baking after exposure to the base resin. It reacts and becomes insoluble in alkali, and as a result, a negative pattern is formed.

The acid generator used here is not limited to dimethylphenylsulfonium triflate, but may be an onium salt, a sulfonic acid ester, a sulfonyloxyimide or the like which generates an acid by ArF excimer laser exposure. It is preferable that the light absorption at 193 nm is small.

The 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate used for the negative mold is not limited to the above, and any reaction related to the base resin may be caused by the generated acid. It is only required to cause the alkali solubility and reduce the alkali solubility. Further, those having a small light absorption at 193 nm are desirable.

<Example 5> The 4,8-bis (hydroxymethyl) tricyclo [5.2.1.0 used in Example 4 was used.
^2,6 ] decane-modified 5-methylenebicyclo [2.2.1]
Instead of the hept-2-ene-maleic anhydride copolymer (D), 1,4-cyclohexanedimethanol-modified 5-ethylenebicyclo [2.2.1] hept-2-ene- synthesized in Synthesis Example 6 A resist solution was prepared using the maleic anhydride copolymer (F) and using 5 parts by weight of triphenylsulfonium triflate instead of 5 parts by weight of dimethylphenylsulfonium triflate as an acid generator.

The resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and heated at 80 ° C. for 2 minutes to form a resist film having a thickness of 0.50 μm. This was exposed to a fine pattern using a KrF excimer laser stepper (NA 0.45).
After the exposure, baking was performed at 100 ° C. for 2 minutes. The development was performed with an aqueous solution of tetramethylammonium hydroxide (0.119% by weight) at 23 ° C. for 90 seconds, followed by rinsing with pure water for 60 seconds. As a result, when the exposure amount was 200 mJ / cm ² , only the unexposed portion of the resist film was dissolved and removed in the developing solution, and a negative 0.35 μm line and space pattern was obtained.

<Example 6> The 4,8-bis (hydroxymethyl) tricyclo [5.2.1.0 used in Example 4 was used.
^2,6 ] decane-modified 5-methylenebicyclo [2.2.1]
Instead of the hept-2-ene-maleic anhydride copolymer (D), the adamantanol-modified 5-synthetic compound synthesized in Synthesis Example 7 was used.
Ethylenebicyclo [2.2.1] hept-2-ene-maleic anhydride copolymer (G) was used, and N-
A resist solution was prepared using 5 parts by weight of (trifluoromethanesulfonyloxy) naphthylimide.

The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and heated at 80 ° C. for 2 minutes to form a resist film having a thickness of 0.53 μm. This was exposed to a fine pattern using a KrF excimer laser stepper (NA 0.45).
After the exposure, baking was performed at 100 ° C. for 2 minutes. The development was performed with an aqueous solution of tetramethylammonium hydroxide (0.119% by weight) at 23 ° C. for 100 seconds, followed by rinsing with pure water for 60 seconds. As a result, when the exposure amount was 240 mJ / cm ² , only the unexposed portion of the resist film was dissolved and removed in the developing solution, and a negative 0.35 μm line and space pattern was obtained.

<Embodiment 7> FIG. 3 shows a well-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 steps of fabricating such a structure consist of dozens of steps. These steps can be roughly divided into three steps: a step up to formation of a field oxide film, a step up to gate formation, and a final step. can do. Here, the process up to the first field oxide film formation (FIG. 4) includes:
A step of forming a resist pattern on the silicon nitride film is included. 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 43 is formed thereon by plasma CVD. I do. A resist pattern 44 having a 0.50 μm line is formed on this substrate by the material and method described in the first embodiment (FIG. 4B). After the silicon nitride film 43 is etched by a known method using this resist pattern as a mask [FIG. 4C], boron ions for channel stopper are implanted using the resist 44 as a mask again. After removing the resist 44 (FIG. 4D), a 1.2 μm field oxide film 45 is formed in the element isolation region by selective oxidation using the silicon nitride film 43 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 43, the gate is oxidized to grow polycrystalline silicon 44 (FIG. 4F). A resist pattern 47 of 0.25 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 46 is etched by a known method to form a gate 48 (FIG. 4H).

Hereinafter, although not shown, the thin oxide film of the source and drain is etched, and then arsenic is diffused in the polycrystalline silicon gate and the source and drain to form an oxide film in the polycrystalline silicon gate and the source and drain regions. I do. The contacts for the aluminum wiring to the gate, source, and drain are viewed from the opening, aluminum deposition and patterning are performed, a protective film is formed, and pads for bonding are opened. Thus, the MOS shown in FIG.
A type transistor is formed.

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

[0118]

According to the present invention, by using a polymer compound having one unit of a carboxylic acid structure in the vicinity with respect to one unit of the cyclic aliphatic hydrocarbon skeleton, the compound is transparent in the far ultraviolet region, and Since dry etching resistance is increased and the surface layer has a dissolving property of being sequentially eluted with an aqueous alkaline developer, a pattern having excellent resolution performance can be formed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the development time of a polymer coating film of Synthesis Example 1 and the intensity of monitor light.

FIG. 2 is a graph showing the relationship between the dissolution time and the film thickness of a polymer coating film of Synthesis Example 1.

FIG. 3 is a cross-sectional view of a MOS 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, 43 .., A silicon nitride film, 44, a resist pattern, 46, a polycrystalline silicon film, 47, a resist pattern, 48, a polycrystalline silicon gate.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Ryoko Yamanaka 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Keiko Hattori 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi Central Research Laboratory

Claims (7)

[Claims] 1. A step of forming a coating film made of a photosensitive composition on a predetermined substrate, and irradiating the coating film with active actinic radiation in a predetermined pattern to form a latent image of a desired pattern in the coating film. And a step of developing a desired pattern in the coating film using an aqueous alkali developing solution, wherein the development with the aqueous alkali developing solution is substantially performed after the formation of the latent image. The following chemical formulas (1) and (2) in the coating film
Wherein R represents at least one group selected from an alkyl group, a cyclic alkyl group, and a cyclic alkyl group having a hydroxyl group, based on aqueous alkali solubility based on the chemical structure represented by ). Embedded image Embedded image 2. A step of forming a coating film made of a photosensitive composition on a predetermined substrate, and irradiating the coating film with active actinic radiation in a predetermined pattern to form a latent image of a desired pattern in the coating film. And a step of developing a desired pattern in the coating film using an aqueous alkali developing solution, wherein the development with the aqueous alkali developing solution is substantially performed after the formation of the latent image. The following chemical formulas (3) and (4) in the coating film
Wherein R represents at least one group selected from an alkyl group, a cyclic alkyl group, and a cyclic alkyl group having a hydroxyl group, based on aqueous alkali solubility based on the chemical structure represented by ). Embedded image Embedded image 3. A step of forming a coating film comprising a photosensitive composition on a predetermined substrate, and irradiating the coating film with active actinic radiation in a predetermined pattern to form a latent image of a desired pattern in the coating film. And a step of developing a desired pattern in the coating film using an aqueous alkali developing solution, wherein the development with the aqueous alkali developing solution is substantially performed after the formation of the latent image. The following chemical formulas (5) and (6) in the coating film
Wherein R represents at least one group selected from an alkyl group, a cyclic alkyl group, and a cyclic alkyl group having a hydroxyl group, based on aqueous alkali solubility based on the chemical structure represented by ). Embedded image Embedded image 4. A step of forming a coating film made of a photosensitive composition on a predetermined substrate, and irradiating the coating film with active actinic radiation in a predetermined pattern to form a latent image of a desired pattern in the coating film. And a step of developing a desired pattern in the coating film using an aqueous alkali developing solution, wherein the development with the aqueous alkali developing solution is substantially performed after the formation of the latent image. The following chemical formulas (7) and (8) in the coating film
Characterized by aqueous alkali solubility based on the chemical structure represented by the formula: Embedded image Embedded image 5. The method for forming a pattern according to claim 1, wherein R in formulas (1) to (8) is selected from the group consisting of:
Is a cycloaliphatic hydrocarbon and a cycloaliphatic hydrocarbon having a hydroxyl group. 6. A method for forming a pattern according to claim 1, wherein a step of forming a latent image of a desired pattern in said coating film by irradiating with an active actinic ray; A step of heating the coating film between the step of developing a desired pattern in the coating film using the method. 7. A step of forming a resist pattern on a semiconductor substrate by the pattern forming method according to claim 1, a step of etching the semiconductor substrate based on the resist pattern, or a step of ion etching. A method of manufacturing a semiconductor device, comprising: