TW201504766A - Resist underlayer film forming composition - Google Patents

Abstract

To provide a novel composition for forming a resist underlayer film. A composition for forming a resist underlayer film, said composition containing a solvent and a polymer that has a constitutional unit that can be represented by formula (1). (1) (In formula (1), X1 represents a C6 - 20 divalent organic group that has at least one aromatic ring that may be substituted with a halogeno group, a nitro group, an amino group, or a hydroxy group; and X2 represents either a methoxy group or a C6 - 20 organic group that has at least one aromatic ring that may be substituted with a halogeno group, a nitro group, an amino group, or a hydroxy group).

Description

Photoresist underlayer film forming composition

The present invention relates to a photoresist underlayer film forming composition for a lithography process. A composition of a photoresist underlayer film which is used to form a high-hardness and which is not easily formed by a photoresist pattern formed by a lithography process.

In the manufacture of semiconductor devices, microfabrication is performed by a lithography process. In the lithography process, when the photoresist layer on the substrate is exposed by an ultraviolet laser such as a KrF excimer laser or an ArF excimer laser, the surface of the substrate is caused by the ultraviolet laser reflection. The problem caused by the wave cannot form a pattern of a photoresist pattern having a desired shape. In order to solve this problem, a photoresist underlayer film (antireflection film) is provided between the substrate and the photoresist layer. Further, as a composition for forming a photoresist underlayer film, a phenol resin is known. For example, Patent Document 1 and Patent Document 2 disclose a photoresist underlayer film forming material containing a resin having a repeating unit obtained by phenolating a compound having a bisphenol group. Further, Patent Document 3 discloses an anti-rotation coating prevention A reflective film composition comprising a polymer having three or more condensed aromatic rings in a main chain of the polymer.

Further, it is known that a photoresist film of at least two layers is formed by forming a thin film of a photoresist layer which is required to be miniaturized with a photoresist pattern, and the photoresist film is used as a mask material. . Examples of the material for forming at least two layers include an organic resin (for example, an acrylic resin, a phenol resin), a ruthenium resin (for example, an organic polysiloxane), and an inorganic ruthenium compound (for example, SiON or SiO ₂ ). When the pattern formed by the above-described organic resin layer is dry-etched as a mask, the pattern must have etching resistance to an etching gas (for example, fluorocarbon). As a composition for forming such an organic resin layer, for example, Patent Document 4 discloses a composition containing a polymer containing a heterocyclic aromatic moiety.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-259249

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2007-316282

[Patent Document 3] Japanese Patent Publication No. 2010-528334

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2007-017976

However, when the photoresist pattern is formed on the substrate to be processed by the above-described lithography process and etching process, the pattern width is formed. The degree is narrow, and there is a problem that the pattern is easily deformed. Specifically, in the case of the underlayer film of the photoresist used as the mask material in the case of processing the substrate for etching purposes, the pattern formed of the organic resin layer has a phenomenon of causing left and right bending.

The present invention is an invention for solving the above problems. That is, the present invention is a photoresist underlayer film forming composition comprising a polymer and a solvent, wherein the polymer has a structural unit represented by the following formula (1), (wherein X ¹ represents a divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring which may be substituted with a halogen group, a nitro group, an amine group or a hydroxyl group, and X ² means a halogen group, A nitro group, an amine group or a hydroxy group having 6 to 20 carbon atoms or a methoxy group having at least one aromatic ring.

Examples of the "halogen group" described above and below include a chlorine group and a bromine group. Examples of the "divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring" as described above and below include, for example, a stretching phenyl group, a stretching phenyl group, a stretching triphenyl group, a stretching group, and an anthracene group. Base, stretch base, stretch a group (base represented by the following formula (a-1) and the following formula (a-2)), a carbazole group (base represented by the following formula (b)), and the following formula (c) The base of the expression (where n is 0 or 1). Examples of the above-mentioned "organic group having 6 to 20 carbon atoms having at least one aromatic ring" include, for example, a phenyl group, a biphenyl group, a triphenylene group, a fluorenyl group, a naphthyl group, an anthracenyl group, an anthracenyl group, and an oxazole. The group represented by the following formula (d-1) and the following formula (d-2) (wherein n represents 0 or 1).

The polymer may further have a structural unit represented by the following formula (2). (wherein X ¹ represents a divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring which may be substituted with a halogen group, a nitro group, an amine group or a hydroxyl group, and R ³ represents a phenyl group or a naphthyl group. , fluorenyl, fluorenyl, thienyl or pyridyl, R ⁴ represents a hydrogen atom, a phenyl group or a naphthyl group, and when R ³ and R ⁴ are each a phenyl group, R ³ and R ⁴ may be bonded to the same The same carbon atom of the bond together forms an anthracene ring).

The photoresist underlayer film forming composition of the present invention may further contain at least one of a crosslinking agent, an acidic compound, a thermal acid generator, and a surfactant as an optional component.

The photoresist underlayer film formed by using the photoresist underlayer film forming composition of the present invention has high hardness, and the wiggling of the pattern formed in the lithography process can be suppressed by applying the photoresist underlayer film.

[Best Mode for Carrying Out the Invention]

The polymer having the structural unit represented by the above formula (1) is contained in the photoresist underlayer film forming composition of the present invention as the polymerization. The structural unit of the object is, for example, a structural unit represented by the following formula (1-1) to formula (1-10).

Further, the structural unit represented by the above formula (2) is, for example, a structural unit represented by the following formula (2-1).

The weight average molecular weight of the polymer contained in the photoresist underlayer film forming composition of the present invention is, for example, 2,000 to 10,000 in terms of a standard polystyrene.

The polymer is an acid catalyst such as a sulfonic acid compound, which is a biphenol compound having two hydroxyphenyl groups, an aromatic compound or a heterocyclic compound, and an aromatic aldehyde or an aromatic ketone required for the reaction. It can be synthesized by carrying out a polymerization reaction in the presence of it. As the "biphenol compound having two hydroxyphenyl groups" used for the synthesis of the above polymer, for example, 3,3',5,5'-tetramethoxymethyl-4,4'-dihydroxyl linkage is exemplified. benzene. Examples of the "aromatic compound" used in the synthesis of the above polymer include benzene, naphthalene, anthracene, anthracene, anthracene, and m-biphenylene. Examples of the "heterocyclic compound" used in the synthesis of the above polymer include carbazole. Examples of the "aromatic aldehyde" used for the synthesis of the above polymer include furfural, pyridinecarboxaldehyde, benzaldehyde, naphthaldehyde, furfural, phenanthrene, salicylaldehyde, phenylacetaldehyde, and 3-benzene. Propionaldehyde, tolualdehyde, (N,N-dimethylamino)benzaldehyde, ethoxylated benzaldehyde, 1-oxime Formaldehyde (1-pyrenecarboxaldehyde), anisaldehyde. Further, examples of the "aromatic ketone"-based diaryl ketone used for the synthesis of the polymer include diphenyl ketone, phenyl naphthyl ketone, dinaphthyl ketone, phenyl tolyl ketone, and xylene. Ketone, 9-fluorenone. The phenolic compound to be used in the synthesis of the polymer is not limited to one type of compound, and two or more kinds thereof may be used. The aromatic compound, the heterocyclic compound, the aromatic aldehyde and the aromatic ketone are not limited to one type. Two or more kinds of compounds can also be used.

The photoresist underlayer film forming composition of the present invention may further contain a crosslinking agent. The crosslinking agent is preferably a crosslinkable compound having at least two crosslinks to form a substituent. For example, a melamine-based compound, a substituted urea-based compound, and a phenol-based compound having a substituent such as a methylol group or a methoxymethyl group to form a substituent may be mentioned. Specifically, a compound such as methoxymethylated acetylene urea or methoxymethylated melamine may, for example, be tetramethoxymethylacetylene urea, tetrabutoxymethylacetylene urea or hexamethoxymethyl. Melamine. Further, examples of the substituted urea compound include tetramethoxymethylurea and tetrabutoxymethylurea. Examples of the phenolic compound include tetrahydroxymethylbiphenol, tetramethoxymethylbiphenol (TMOM-BP), and tetramethoxymethylbisphenol.

As the crosslinking agent, a compound having at least two epoxy groups can also be used. As such a compound, for example, ginseng (2,3-epoxypropyl)isocyanate, 1,4-butanediol diepoxypropyl ether, 1,2-epoxy group -4-(epoxyethyl)cyclohexane, glycerol triepoxypropyl ether, diethylene glycol diepoxypropyl ether, 2,6-diepoxypropyl phenylepoxypropyl ether, 1, 1,3-para [p-(2,3-epoxypropoxy)phenyl]propane, 1,2- Dicyclopropyl propyl cyclohexanedicarboxylate, 4,4'-methylenebis(N,N-diepoxypropylaniline), 3,4-epoxycyclohexylmethyl-3,4 - Epoxycyclohexane carboxylate, trimethylolethane triepoxypropyl ether, bisphenol-A-diglycidyl ether, Epolide [registered trademark] GT-401 manufactured by Daicel Same as GT-403, GT-301, GT-302, Ceroxide [registered trademark] 2021, same 3000, Mitsubishi Chemical Co., Ltd., 1001, 1002, 1003, 1004, 1007, 1009, 1010, 828, 807 152, 154, 180S75, 871, 872, EPPN201, 202, EOCN-102, 103S, 104S, 1020, 1025, 1027, Nagase ChemteX (shares) made by Nippon Chemical Co., Ltd. Denacol [registered trademark] EX-252, same as EX-611, with EX-612, with EX-614, with EX-622, with EX-411, with EX-512, with EX-522, with EX-421, with EX-313, with EX-314, with EX-321, BASF JAPAN (share) CY175, CY177, CY179, CY182, CY184, CY192, DIC (share) Epiclon 200, same 400, same 7015, same 835LV Same as 850CRP. As the compound having at least two epoxy groups, an epoxy group having an amine group can also be used. Examples of such an epoxy resin include YH-434 and YH-434L (Nippon Chemical Co., Ltd.).

As the crosslinking agent, a compound having at least two blocked isocyanate groups can also be used. Examples of such a compound include Takenate [registered trademark] B-830 manufactured by Mitsui Chemicals Co., Ltd., and B-870N, and VESTANAT [registered trademark] B1358/100 manufactured by Evonik Degussa Co., Ltd.

As the crosslinking agent, a compound having at least two vinyl ether groups can also be used. Examples of such a compound include bis(4-(vinyloxymethyl)cyclohexylmethyl)pentanesuccinate, tris(ethylene glycol) divinyl ether, and divinyl adipate. , diethylene glycol divinyl ether, 1,2,4- cis (4-vinyloxybutyl) trimellitate, 1,3,5-gin (4-vinyloxybutyl) Pyromellitate, bis(4-(vinyloxy)butyl)paraphthalate, bis(4-(vinyloxy)butyl)isodecanoate, ethylene glycol divinyl ether, 1,4-butanediol divinyl ether, butanediol divinyl ether, tetraethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, three Hydroxymethylethane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol triethylene Ethyl ether and cyclohexane dimethanol divinyl ether.

One type of various crosslinking agents selected from these may be added, and two or more types may be added in combination. The content ratio of the crosslinking agent is, for example, 2% by mass to 60% by mass based on the solid content of the solvent to be described later from the photoresist underlayer film forming composition of the present invention.

The photoresist underlayer film forming composition of the present invention may further contain an acidic compound. The acidic compound functions as a catalyst for promoting a crosslinking reaction, and examples thereof include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate, salicylic acid, camphorsulfonic acid, 5- Sulfonic acid compounds and carboxylic acid compounds of sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, etc. A mineral acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid. Can replace the above acid compound Or a thermal acid generator together with the above acidic compound. The thermal acid generator also functions as a catalyst for promoting the crosslinking reaction, and examples thereof include a fourth-order ammonium salt of trifluoromethanesulfonic acid. One type of the acidic compound and the thermal acid generator may be added, and two or more types may be added in combination. The content ratio of the acidic compound or the thermal acid generator is, for example, 0.1% by mass to 20% by mass based on the solid content of the solvent to be described later from the photoresist underlayer film forming composition of the present invention.

The photoresist underlayer film forming composition of the present invention may further contain a surfactant. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl sulfonyl ether, polyoxyethylene hexadecyl ether, and polyoxyethylene oleyl ether. Polyoxyethylene alkyl aryl ether, polyoxyethylene ‧ polyoxypropylene block copolymer, sorbitan monolaurate Sorbitol fatty acid esters such as sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate , polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitol A nonionic surfactant such as a polyoxyethylene sorbitan fatty acid ester such as an alcoholic anhydride tristearate, Eftop [registered trademark] EF301, EF303, and EF352 (manufactured by Mitsubishi Materials Corporation) Megafac [registered trademark] F171, with F173, with R-30, with R-30-N, with R-40, with R-40-LM (DIC) ), Fluorad FC430, FC431 (Sumitomo 3M (share) system), Asahiguide [registered trademark] AG710, Surflon [registered trademark] S-382, same as SC101, with SC102, with SC103, with SC104, with SC105, with SC106 (asahi (product)), fluorine-based surfactant, organic polyoxyalkylene polymer KP341 ( Shin-Etsu Chemical Industry Co., Ltd.). One type of the surfactant selected from these may be added, or two or more types may be added in combination. The content ratio of the surfactant is, for example, 0.01% by mass to 5% by mass based on the solid content of the solvent to be described later from the photoresist underlayer film forming composition of the present invention.

The photoresist underlayer film forming composition of the present invention can be prepared by dissolving the above components in a suitable solvent, and is used in a uniform solution state. Examples of such a solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, and propylene glycol monomethyl ether. , propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, methyl cyproterone acetate, ethyl cyproterone acetate, toluene, xylene, methyl ethyl Ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropanoate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3- Methyl methyl butyrate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, acetone Ester, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrole Pyridone. These organic solvents may be used alone or in combination of two or more. The ratio of the solid content of the organic solvent removed from the above composition is, for example, 0.5% by mass to 30% by mass, preferably 0.8% by mass to 15% by mass.

Coating and baking the photoresist underlayer film forming composition of the present invention The baking step is performed on a substrate (for example, a germanium wafer, and the germanium wafer may be coated with a tantalum oxide film, a tantalum nitride film, a tantalum oxide film, or a metal film of aluminum or tungsten). The composition is applied by a suitable coating method such as a spin coater or an applicator, and then it is carried out by baking using a heating means such as a hot plate. In terms of baking conditions, it may be suitably selected from a baking temperature of from 100 ° C to 400 ° C and a baking time of from 0.3 minutes to 10 minutes.

An organic polysiloxane film is formed on the first photoresist underlayer film formed by the above steps as a second photoresist underlayer film, and a photoresist pattern is formed thereon. The second photoresist underlayer film may be an SiON film or a SiN film formed by a vapor deposition method such as CVD or PVD. Further, an antireflection film (BARC) may be formed on the second photoresist underlayer film as the third photoresist underlayer film, and the third photoresist underlayer film may be a photoresist shape correction film having no antireflection energy. In the step of forming the aforementioned photoresist pattern, exposure is performed by forming a mask for a specified pattern or by direct drawing. As the exposure source, for example, a g line, an i line, a KrF excimer laser, an ArF excimer laser, an EUV, an electron line can be used. After exposure, Post Exposure Bake can be performed as needed. Thereafter, development is carried out by a developing solution (for example, 2.38 mass% aqueous solution of tetramethylammonium hydroxide), and a rinse liquid or pure water is further injected to remove the used developer. Thereafter, the photoresist pattern is dried and the adhesion to the substrate is improved, followed by baking.

The etching step performed after the formation of the photoresist pattern is performed by dry etching. The etching gas used for the dry etching is, for example, CHF ₃ , CF ₄ , or C ₂ F ₆ for the second photoresist lower layer film (organic polyoxyalkylene film), and the lower layer for the photoresist of the present invention. The first photoresist underlayer film formed of the film formation composition may, for example, be O ₂ , N ₂ O or NO ₂ , and for the surface having a step or a concave portion and/or a convex portion, for example, CHF ₃ may be mentioned. , CF ₄ , C ₂ F ₆ . Further, these gases may be used after mixing argon, nitrogen or carbon dioxide.

[Examples]

Hereinafter, the present invention will be described by way of Synthesis Examples and Examples, but the present invention is not limited by the following description.

The weight average molecular weight and polydispersity shown in the following Synthesis Example 1 to Synthesis Example 3, Comparative Synthesis Example 1 and Comparative Synthesis Example 2 are obtained by gel permeation chromatography (hereinafter, abbreviated as GPC in the present specification). The measurement results. The measurement system used a GPC system manufactured by Tosoh Co., Ltd., and the measurement conditions were as follows.

GPC pipe column: TSKgel SuperMultipore [registered trademark] Hz-N (Dongcao (share))

Column temperature: 40 ° C

Solvent: tetrahydrofuran (THF)

Flow rate: 0.35ml/min

Standard sample: polystyrene (Dongcao (share))

(Synthesis Example 1)

3,3',5,5'-tetramethoxymethyl-4,4'-dihydroxybiphenyl (hereinafter, abbreviated as TMOM-BP in the present specification) (23.83 g, 0.066) was added to a 200 mL four-necked flask. Mol, Honshu Chemical Industry Co., Ltd.) (27.00g, 0.134mol, manufactured by Tokyo Chemical Industry Co., Ltd.), p-toluenesulfonic acid monohydrate (0.53g, 0.003mol, manufactured by Tokyo Chemical Industry Co., Ltd.), and then placed with 1,4-oxane (119.84) g. Kanto Chemical Co., Ltd.), stirred, and heated until the reflux was confirmed, dissolved and started to polymerize. After 6 hours, it was allowed to cool to 60 ° C, and then reprecipitated in methanol (1000 g, manufactured by Kanto Chemical Co., Ltd.). The obtained precipitate was filtered and dried using a vacuum dryer at 60 ° C for 12 hours to obtain a polymer having the objective of the following formula (3) (hereinafter, abbreviated as TMOM in the present specification) -Py) 28.6g. The obtained TMOM-Py had a weight average molecular weight of 2,600 in terms of polystyrene measured by GPC.

(Synthesis Example 2)

TMOM-BP (2.21g, 0.006mol, manufactured by Honshu Chemical Industry Co., Ltd.), carbazole (5.00g, 0.030mol) was added to a 100 mL four-necked flask. , Tokyo Chemical Industry Co., Ltd.), 1-pyrenecarboxaldehyde (5.76 g, 0.025 mol, manufactured by Sigma-Aldrich Co., Ltd.), p-toluenesulfonic acid monohydrate (0.89 g, 0.006 mol, Tokyo Chemical Industry Co., Ltd.) (manufactured by the company), 1,4-oxane (25.75 g, manufactured by Kanto Chemical Co., Ltd.) was placed, stirred, and the temperature was raised until the reflux was confirmed, and the polymerization was started. After 7 hours, it was allowed to cool to 60 ° C, and then reprecipitated in methanol (1000 g, manufactured by Kanto Chemical Co., Ltd.). The obtained precipitate was filtered, and dried at 60 ° C for 12 hours using a vacuum dryer to obtain a polymer having the following two structural units represented by the following formula (4) (hereinafter, abbreviated in the present specification) For TMOM-Cz-PCA) 6.3g. The weight average molecular weight of the obtained TMOM-Cz-PCA measured by GPC in terms of polystyrene was 8,900.

(Synthesis Example 3)

To a 200 mL four-necked flask, TMOM-BP (13.93 g, 0.038 mol, manufactured by Honshu Chemical Industry Co., Ltd.), naphthalene (10.00 g, 0.078 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), p-toluenesulfonic acid monohydrate was added. (0.31 g, 0.002 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), and then placed 1,4-oxane (56.56 g, manufactured by Kanto Chemical Co., Ltd.), stirred, and heated until the reflux was confirmed to dissolve. And start to aggregate. After 5 hours, it was allowed to cool to 60 ° C, and then reprecipitated in methanol (1000 g, manufactured by Kanto Chemical Co., Ltd.). The obtained precipitate was filtered, and dried at 60 ° C for 12 hours using a vacuum dryer to obtain a polymer having the objective of the following formula (5) (hereinafter, abbreviated as TMOM in the present specification) -Na) 5.9 g. The obtained TMOM-Na had a weight average molecular weight of 5,000 in terms of polystyrene measured by GPC.

(Comparative Synthesis Example 1)

Add carbazole (6.69 g, in a 100 mL four-necked flask under nitrogen) 0.040 mol, manufactured by Tokyo Chemical Industry Co., Ltd., 9-fluorenone (7.28 g, 0.040 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), p-toluenesulfonic acid monohydrate (0.76 g, 0.0040 mol, Tokyo Chemical Industry Co., Ltd.) In the system), 1,4-oxane (6.69 g, manufactured by Kanto Chemical Co., Ltd.) was placed, stirred, and heated to 100 ° C to dissolve and start polymerization. After 24 hours, it was allowed to cool to 60 ° C, and then chloroform (34 g, manufactured by Kanto Chemical Co., Ltd.) was added to dilute it, and it was reprecipitated in methanol (168 g, manufactured by Kanto Chemical Co., Ltd.). The obtained precipitate was filtered, and dried at 80 ° C for 24 hours using a vacuum dryer to obtain 9.37 g of a polymer having a structural unit represented by the following formula (6). The obtained polymer had a weight average molecular weight of 2,800 in terms of polystyrene as measured by GPC.

(Example 1)

To a solution of 20 g of the polymer obtained in Synthesis Example 1, a mixed surfactant of 0.06 g of Megafac R-30 (manufactured by DIC Co., Ltd.) was dissolved in 80 g of cyclohexanone to prepare a solution. Thereafter, filtration was carried out using a polyethylene microfilter having a pore size of 0.10 μm, and a polyethylene microfilter having a pore diameter of 0.05 μm was further used. Filtration was carried out to prepare a composition for forming a photoresist film for a lithography process composed of a multilayer film.

(Example 2)

To 20 g of a polymer obtained in Synthesis Example 2, 0.06 g of Megafac R-30 (manufactured by DIC Co., Ltd.) was mixed with a surfactant, and dissolved in 80 g of cyclohexanone to prepare a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a photoreceptor underlayer film formed by a multilayer film. Things.

(Example 3)

To 20 g of a polymer obtained in Synthesis Example 3, 0.06 g of Megafac R-30 (manufactured by DIC Co., Ltd.) was mixed with a surfactant, and dissolved in 80 g of cyclohexanone to prepare a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a photoreceptor underlayer film formed by a multilayer film. Things.

(Comparative Example 1)

To a mixture of 20 g of a polymer obtained in Synthesis Example 1 and 0.06 g of Megafac R-30 (manufactured by DIC Co., Ltd.), which was mixed with a surfactant, was dissolved in 80 g of cyclohexanone to prepare a solution. Thereafter, filtration was carried out using a polyethylene microfilter having a pore size of 0.10 μm, and further, a microfiltration of polyethylene having a pore diameter of 0.05 μm was further used. The device is filtered to form a composition for forming a photoresist film for a lithography process composed of a multilayer film.

(Comparative Example 2)

For the comparison of 20 g of the polymer obtained in Synthesis Example 1, 3.0 g of TMOM-BP (manufactured by Honshu Chemical Co., Ltd.) and 0.6 g of pyridinium p-toluenesulfonate as a catalyst were mixed as a crosslinking agent. 0.06 g of Megafac R-30 (manufactured by DIC Co., Ltd.) was dissolved in 80 g of cyclohexanone to prepare a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a photoreceptor underlayer film formed by a multilayer film. Things.

(Measurement of hardness of film)

The photoresist underlayer film forming compositions prepared in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 were applied onto a tantalum wafer using a spin coater. The coated wafer was baked on a hot plate at 240 ° C for 1 minute or at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness 0.25 μm). These photoresist underlayer films were measured for hardness by using a nanoindenter apparatus G200 (manufactured by Agilent Technologies). The results are shown in Table 1.

From the results of Table 1 above, it was found that the photoresist underlayer film formed by baking the film under the photoresist of Examples 1 to 3 of the present invention and baked at 400 ° C for 2 minutes was compared. The photoresist underlayer film (Examples 1 to 3) of the present invention has high hardness after the photoresist underlayer film formed by using the photoresist underlayer film of Comparative Example 1 and Comparative Example 2 and baked under the same conditions. .

(Solution test for photoresist solvent)

The photoresist underlayer film forming compositions prepared in Examples 1 to 3 and Comparative Example 1 were applied onto a tantalum wafer, respectively, using a spin coater. The coated wafer was baked on a hot plate at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness 0.25 μm). This photoresist underlayer film was immersed in a solvent (ethyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or cyclohexanone) used for the photoresist, and it was confirmed that it was insoluble in these solvents.

(measurement of optical parameters)

The photoresist underlayer film forming compositions prepared in Examples 1 to 3 were respectively applied onto a tantalum wafer using a spin coater. The coated wafer was baked on a hot plate at 240 ° C for 1 minute or at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness 0.05 μm). These resistive underlayer films were measured using a spectroscopic elliptical thickness gauge to measure the refractive index (n value) at a wavelength of 193 nm and the optical absorptivity (k value, also referred to as an attenuation coefficient). The results are shown in Table 2.

(Measurement of heat resistance)

The photoresist underlayer film forming compositions prepared in Examples 1 to 3 were respectively applied onto a tantalum wafer using a spin coater. The coated wafer was baked on a hot plate at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness 0.2 μm). These photoresist underlayer films were scraped from the tantalum wafer to obtain a powder. The thermal weight reduction of the obtained powder body at 400 ° C was measured using TG/DTA (TG-DTA2010SR manufactured by BRUKER Co., Ltd.). The results are shown in Table 3.

(Measurement of dry etching speed)

The etcher and etching gas used for the measurement of the dry etching rate are as follows.

Etch: RIE-10NR (made by Samco)

Etching gas: CF ₄

The photoresist underlayer film forming compositions prepared in Examples 1 to 3 were respectively applied onto a tantalum wafer using a spin coater. The coated wafer was baked on a hot plate at 240 ° C for 1 minute or at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness 0.25 μm). Next, the dry etching rate of the underlying film of these photoresists was measured using CF ₄ gas as an etching gas. Further, a solution of a phenol novolac resin (a commercially available product, a weight average molecular weight Mw measured by polystyrene in terms of polystyrene of 2000 and a polydispersity Mw/Mn of 2.5) obtained by a GPC was applied onto a tantalum wafer using a spin coater. The phenol phenol resin film (film thickness: 0.25 μm) was formed by baking at 205 ° C for 1 minute on a hot plate. Next, CF ₄ gas as an etching gas was used, and the dry etching rate of the phenol phenol resin film was measured. When the dry etching rate of the phenol phenol resin film was set to 1.00, the dry etching rate of the photoresist underlayer film formed by the photoresist underlayer film forming compositions prepared in Examples 1 to 3 was calculated as the dry etching rate ratio. The results are shown in Table 4. The smaller the dry etching rate ratio, the higher the etching resistance to CF ₄ gas.

Dry etching rate ratio = (dry etching rate of photoresist underlayer film) / (dry etching rate of phenol novolak film)

(Confirmation of the width of the curved pattern)

The photoresist underlayer film forming compositions prepared in Examples 1 to 3 and Comparative Example 2 were applied onto a tantalum wafer with a hafnium oxide film, respectively, using a spin coater. The coated wafer was baked on a hot plate at 400 ° C for 2 minutes to form a photoresist underlayer film (film thickness: 200 nm). A conventional hard mask forming composition containing polyoxyalkylene was applied onto the underlayer film of the photoresist, and baked at 240 ° C for 1 minute to form a hard mask layer (film thickness: 45 nm). Further, a photoresist solution (PAR855 S90 (manufactured by Sumitomo Chemical Co., Ltd.)) was applied thereon, and baked at 100 ° C for 1 minute to form a photoresist layer (film thickness: 120 nm). This photoresist layer was exposed to light at a wavelength of 193 nm using a mask, and subjected to post-exposure heating (PEB at 105 ° C for 1 minute), followed by development to obtain a photoresist pattern. Thereafter, dry etching is performed using a fluorine-based gas (component is CF ₄ ), and the photoresist pattern is transferred to the hard mask layer. Next, dry etching is performed using an oxygen-based gas (component is O ₂ ), and the photoresist pattern is transferred to the photoresist underlayer film. Thereafter, dry etching is performed using a fluorine-based gas (component is C ₄ F ₈ ) to remove the cerium oxide film on the germanium wafer. Finally, an electron microscope was used to observe the shape of the pattern obtained separately.

As the width of the pattern is narrowed, it is easy to produce a curvature of an irregular pattern called wiggling. Therefore, the above-described pattern is formed by using the photoresist underlayer film forming composition prepared in the above-described Embodiments 1 to 3. In the type forming step, it was observed by an electron microscope that the resulting pattern had begun to appear to be wigling. When a pattern wagling occurs, the substrate cannot be processed based on a faithful pattern. Therefore, the substrate width (bound pattern width) before the curvature (wavy) of the pattern is generated machining. The boundary pattern width of the wiggling of the pattern is started to be generated, and the narrower the value, the finer substrate processing can be performed. The measurement of the resolution was performed using a length-measuring scanning electron microscope (manufactured by Hitachi High-Technologies). The measurement results are shown in Table 5.

In the lithographic process photoresist underlayer film formed of a multilayer film of the present invention, a photoresist underlayer film which can also serve as an antireflection film can be provided. Further, the photoresist underlayer film forming composition of the present invention is known It has heat resistance in which a hard mask can be formed by a CVD method on its upper layer. Further, even in the case where the width of the pattern is reduced, it is less likely to cause wiggling of the pattern and a good pattern can be obtained, and a pattern having a pattern width of at least about 50 nm is obtained as a good pattern in which no bending occurs.

Claims (6)

A photoresist underlayer film forming composition comprising a polymer and a solvent, wherein the polymer has a structural unit represented by the following formula (1), (wherein X ¹ represents a divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring which may be substituted with a halogen group, a nitro group, an amine group or a hydroxyl group, and X ² means a halogen group, A nitro group, an amine group or a hydroxy group having 6 to 20 carbon atoms or a methoxy group having at least one aromatic ring. The photoreceptor underlayer film forming composition of claim 1, wherein in the above formula (1), the divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring is a phenyl group, a biphenyl group, Extending a triphenyl, anthracenyl, anthranyl, anthracenyl, anthracenyl, carbazolyl or a group represented by the following formula (c): wherein n represents 0 or 1; At least one aromatic ring having 6 to 20 carbon atoms, an organic group phenyl group, a biphenyl group, a triphenylene group, a fluorenyl group, a naphthyl group, an anthracenyl group, an anthracenyl group, an oxazolyl group, or the following formula (d) -1) or a group represented by the following formula (d-2) (wherein n represents 0 or 1; The photoresist underlayer film forming composition according to claim 1 or claim 2, wherein the polymer system further has a structural unit represented by the following formula (2), (wherein X ¹ is synonymous with the definition described in claim 1; R ³ represents a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, a thienyl group or a pyridyl group, and R ⁴ represents a hydrogen atom, a phenyl group or a naphthalene group; Further, when R ³ and R ⁴ are each represented as a phenyl group, R ³ and R ⁴ may form an anthracene ring together with the same carbon atom to which they are bonded. The photoresist underlayer film forming composition according to any one of claims 1 to 3, further comprising a surfactant. The photoresist underlayer film forming composition according to any one of claims 1 to 4, further comprising a crosslinking agent. The photoresist underlayer film forming composition according to any one of claims 1 to 5, further comprising an acidic compound and/or an acid generator.