JP2016145849A - Composition for forming resist underlay film containing trihydroxynaphthalene novolac resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a resist underlay film, which has heat resistance and wiggling resistance of a pattern to be used for a lithographic process in manufacturing a semiconductor device.SOLUTION: The composition for forming a resist underlay film for lithography comprises a polymer having a structural unit of formula (1). In formula (1), A represents a hydroxy group-substituted naphthylene group derived from polyhydroxynaphthalene and having 3 hydroxy groups; and B represents a monovalent condensed aromatic hydrocarbon cyclic group in which 2 to 4 benzene rings are condensed.SELECTED DRAWING: None

Description

  The present invention relates to a resist underlayer film forming composition for lithography effective at the time of processing a semiconductor substrate, a resist pattern forming method using the resist underlayer film forming composition, and a method for manufacturing a semiconductor device.

  Conventionally, in the manufacture of semiconductor devices, fine processing by lithography using a photoresist composition has been performed. In the fine processing, a thin film of a photoresist composition is formed on a substrate to be processed such as a silicon wafer, and irradiated with actinic rays such as ultraviolet rays through a mask pattern on which a semiconductor device pattern is drawn, and developed. This is a processing method for etching a substrate to be processed such as a silicon wafer using the obtained photoresist pattern as a protective film. However, in recent years, the degree of integration of semiconductor devices has increased, and the actinic rays used tend to be shortened from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). Accordingly, the influence of diffuse reflection of active rays from the substrate and standing waves has been a serious problem. Therefore, a method of providing an antireflection film (Bottom Anti-Reflective Coating, BARC) between the photoresist and the substrate to be processed has been widely studied.

  In the future, as the miniaturization of the resist pattern proceeds, there arises a problem of resolution and a problem that the resist pattern collapses after development, and it is desired to reduce the thickness of the resist. For this reason, it is difficult to obtain a resist pattern film thickness sufficient for substrate processing, and not only the resist pattern but also the resist underlayer film formed between the resist and the semiconductor substrate to be processed functions as a mask during substrate processing. The process to have it has become necessary. Unlike conventional resist underlayer films with high etch rate (fast etching speed) as resist underlayer films for such processes, compared to resist underlayer films and resists for lithography, which have a selectivity of dry etching rate close to that of resist There has been a demand for a resist underlayer film for lithography having a low dry etching rate selection ratio and a resist underlayer film for lithography having a low dry etching rate selection ratio compared to a semiconductor substrate.

  As a polymer used in the resist underlayer film forming composition, a novolak resin of dihydroxynaphthalene and benzaldehyde or naphthaldehyde is disclosed (see Patent Document 1).

  As a polymer used in the resist underlayer film forming composition, a polyhydroxybenzene novolak resin is disclosed (see Patent Document 2).

JP2009-229666 International Patent Application WO2012 / 176767 Pamphlet

  An object of the present invention is to provide a resist underlayer film forming composition for use in a lithography process for manufacturing a semiconductor device. In addition, the present invention does not cause intermixing with the resist layer, provides an excellent resist pattern, and has a dry etching rate selection ratio close to that of the resist. An object of the present invention is to provide a resist underlayer film for lithography having a ratio and a resist underlayer film for lithography having a low dry etching rate selection ratio as compared with a semiconductor substrate. In addition, the present invention can also provide the ability to effectively absorb the reflected light from the substrate when using irradiation light having a wavelength of 248 nm, 193 nm, 157 nm or the like for fine processing. Furthermore, this invention is providing the formation method of the resist pattern using the resist underlayer film forming composition. And the resist underlayer film forming composition for forming the resist underlayer film which also has heat resistance is provided.

As a first aspect of the present invention, the formula (1):

(In the formula (1), A is a hydroxy group-substituted naphthylene group derived from polyhydroxynaphthalene, has 3 hydroxy groups, and B is a monovalent condensed aromatic carbonized with 2 to 4 benzene rings condensed. A composition for forming a resist underlayer film for lithography comprising a polymer containing a unit structure of a hydrogen ring group),
As a second aspect, the resist underlayer film forming composition according to the first aspect, wherein A is a hydroxy-substituted naphthylene group derived from trihydroxynaphthalene,
As a third aspect, the resist underlayer film forming composition according to the first aspect or the second aspect, in which the condensed aromatic hydrocarbon ring group of B is a naphthalene ring group, an anthracene ring group, or a pyrene ring group,
As a fourth aspect, the condensed aromatic hydrocarbon ring group of B has a halogen group, hydroxyl group, nitro group, amino group, carboxyl group, carboxylic acid ester group, nitrile group, or a combination thereof as a substituent. The resist underlayer film forming composition according to any one of the first aspect to the third aspect,
As a fifth aspect, the resist underlayer film forming composition according to any one of the first aspect to the fourth aspect, further including a crosslinking agent,
As a sixth aspect, the resist underlayer film forming composition according to any one of the first aspect to the fifth aspect, further comprising an acid and / or an acid generator,
As a seventh aspect, a resist underlayer film obtained by applying and baking the resist underlayer film forming composition according to any one of the first to sixth aspects on a semiconductor substrate,
As an eighth aspect, the resist underlayer film forming composition according to any one of the first to sixth aspects is applied on a semiconductor substrate and baked to form a lower layer film. Forming a resist pattern;
As a ninth aspect, a step of forming an underlayer film on the semiconductor substrate with the resist underlayer film forming composition according to any one of the first to sixth aspects, a step of forming a resist film thereon, light or A method of manufacturing a semiconductor device, comprising: a step of forming a resist pattern by electron beam irradiation and development; a step of etching the lower layer film with a resist pattern; and a step of processing a semiconductor substrate with a patterned lower layer film;
As a tenth aspect, a step of forming an underlayer film on the semiconductor substrate with the resist underlayer film forming composition according to any one of the first to sixth aspects, a step of forming a hard mask thereon, and further thereon A step of forming a resist film on the substrate, a step of forming a resist pattern by light and electron beam irradiation and development, a step of etching a hard mask with the resist pattern, a step of etching the lower layer film with a patterned hard mask, and A manufacturing method of a semiconductor device including a step of processing a semiconductor substrate with a patterned underlayer film, and, as an eleventh aspect, described in the tenth aspect, wherein the hard mask is formed by an inorganic coating or inorganic deposition. It is a manufacturing method.

With the resist underlayer film forming composition of the present invention, a good resist pattern shape can be formed without causing intermixing between the upper layer portion of the resist underlayer film and the layer coated thereon.

  The resist underlayer film forming composition of the present invention can be imparted with the ability to efficiently suppress reflection from the substrate, and can also have an effect as an antireflection film for exposure light.

  With the resist underlayer film forming composition of the present invention, the dry etching rate selectivity close to the resist, the dry etching rate selectivity lower than that of the resist, and the dry etching rate selectivity lower than that of the semiconductor substrate are excellent. A resist underlayer film can be provided.

  In order to prevent the resist pattern from collapsing after development with the miniaturization of the resist pattern, the resist is thinned. In such a thin film resist, the resist pattern is transferred to the lower layer film by an etching process, the substrate processing is performed using the lower layer film as a mask, or the resist pattern is transferred to the lower layer film by an etching process, and further to the lower layer film. There is a process in which the process of transferring the transferred pattern to the lower layer film using a different gas composition is repeated to finally process the substrate. The resist underlayer film and the composition for forming the resist of the present invention are effective for this process. When a substrate is processed using the resist underlayer film of the present invention, a processed substrate (for example, a thermal silicon oxide film on the substrate, silicon nitride) Film, polysilicon film, etc.) having sufficient etching resistance.

  The resist underlayer film of the present invention can be used as a planarizing film, a resist underlayer film, a resist layer antifouling film, or a film having dry etch selectivity. This makes it possible to easily and accurately form a resist pattern in a lithography process for manufacturing a semiconductor.

  A resist underlayer film formed by the resist underlayer film forming composition according to the present invention is formed on a substrate, a hard mask is formed thereon, a resist film is formed thereon, a resist pattern is formed by exposure and development, and dry etching is performed. There is a process in which the resist pattern is transferred to a hard mask by the above, the resist pattern transferred to the hard mask by dry etching is transferred to the resist underlayer film, and the semiconductor substrate is processed by the resist underlayer film. When dry etching is performed with a dry etching gas, the pattern formed by the resist underlayer film of the present invention is a pattern excellent in pattern bending resistance (anti-wiggling).

  In this process, the hard mask may be formed by a coating composition containing an organic polymer or inorganic polymer (silicon polymer) and a solvent, or by vacuum deposition of an inorganic substance. In the vacuum deposition of an inorganic material (for example, silicon nitride oxide), the deposited material is deposited on the resist underlayer film surface. At this time, the temperature of the resist underlayer film surface rises to around 400 ° C. In the present invention, since the polymer used is a polymer containing many benzene-based unit structures, the heat resistance is extremely high, and thermal degradation does not occur even when deposits are deposited.

  The present invention is a resist underlayer film forming composition for lithography comprising a polymer containing a unit structure of formula (1).

  The polymer can be used as a novolak resin obtained by condensing trihydroxynaphthalene and an aldehyde.

In the present invention, the resist underlayer film forming composition for lithography includes the polymer and a solvent. And it can contain a crosslinking agent and an acid, and can contain additives, such as an acid generator and surfactant, as needed. The solid content of this composition is 0.1 to 70% by mass, or 0.1 to 60% by mass. The solid content is the content ratio of all components excluding the solvent from the resist underlayer film forming composition. The polymer is contained in a solid content in a proportion of 1 to 100% by mass, or 1 to 99.9% by mass, or 50 to 99.9% by mass, or 50 to 95% by mass, or 50 to 90% by mass. Can do.
The polymer used in the present invention has a weight average molecular weight of 600 to 1,000,000, or 600 to 200,000, 600 to 100,000, or 600 to 10,000, or 1000 to 5000, or 1500 to 3000.

  In formula (1), A is a hydroxy group-substituted naphthylene group derived from polyhydroxynaphthalene, and B is a monovalent condensed aromatic hydrocarbon ring group in which 2 to 4 benzene rings are condensed.

  The condensed aromatic hydrocarbon ring group of B can be a naphthalene ring group, an anthracene ring group, or a pyrene ring group. A naphthalene ring group and a pyrene ring group can be preferably used. A pyrene ring group can be preferably used.

  Examples of the unit structure of the above formula (1) can be exemplified below.

  In this invention, the novolak resin containing the repeating unit structure of Formula (1) which condensed trihydroxynaphthalene and aldehyde can be used as a polymer.

  The aldehyde is an aldehyde having a condensed aromatic hydrocarbon ring group such as naphthalene, anthracene, or pyrene, and examples thereof include naphthaldehyde, anthracene carboxaldehyde, and pyrene carboxaldehyde.

In this reaction, the aldehyde can be reacted at a ratio of 0.1 to 10 mol, preferably 0.8 to 2.2 mol, and more preferably 1.0 mol with respect to 1 mol of the phenol.
Examples of the acid catalyst used in the condensation reaction include mineral acids such as sulfuric acid, phosphoric acid and perchloric acid, organic sulfonic acids such as p-toluenesulfonic acid and p-toluenesulfonic acid monohydrate, formic acid and oxalic acid. Carboxylic acids such as are used. The amount of the acid catalyst used is variously selected depending on the type of acids used. Usually, it is 0.001-10000 mass parts with respect to 100 mass parts of the total of the said phenols and aldehyde, Preferably, it is 0.01-1000 mass parts, More preferably, it is 0.1-100 mass parts.
The above condensation reaction is carried out without a solvent, but is usually carried out using a solvent. Any solvent that does not inhibit the reaction can be used. Examples thereof include cyclic ethers such as tetrahydrofuran and dioxane. In addition, if the acid catalyst used is a liquid such as formic acid, it can also serve as a solvent.
The reaction temperature during the condensation is usually 40 ° C to 200 ° C. The reaction time is variously selected depending on the reaction temperature, but is usually about 30 minutes to 50 hours.
The weight average molecular weight Mw of the polymer obtained as described above is usually 600 to 1,000,000, or 600 to 200,000, 600 to 100,000, or 600 to 10,000, or 1000 to 5000, or 1500 to 3000.
The said polymer can mix and use another polymer within 30 mass% in all the polymers.

These polymers include polyacrylic acid ester compounds, polymethacrylic acid ester compounds, polyacrylamide compounds, polymethacrylamide compounds, polyvinyl compounds, polystyrene compounds, polymaleimide compounds, polymaleic anhydrides, and polyacrylonitrile compounds.
Examples of the raw material monomer for the polyacrylate compound include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthryl methyl acrylate, phenyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2,2,2-trifluoroethyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate , Tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 2-methoxybutyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, 8 -Ethyl-8-tricyclodecyl acrylate, 5-acryloyloxy-6-hydroxynorbornene-2-carboxyl-6-lactone, and the like.

The raw material monomers for the polymethacrylic acid ester compound include ethyl methacrylate, normal propyl methacrylate, normal pentyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthryl methyl methacrylate, phenyl methacrylate, 2-phenylethyl methacrylate, 2 -Hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,2-trichloroethyl methacrylate, methyl acrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, normal lauryl methacrylate Normal stearyl methacrylate , Methoxydiethylene glycol methacrylate, methoxy polyethylene glycol methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, tert-butyl methacrylate, isostearyl methacrylate, normal butoxyethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 2-methyl-2- Adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, 2-propyl-2-adamantyl methacrylate, 2-methoxybutyl-2-adamantyl methacrylate, 8-methyl-8-tricyclodecyl methacrylate, 8-ethyl-8-tricyclo Decyl methacrylate, 5-methacryloyloxy-6-hydroxynorbornene-2-carboxylic 6-lactone, and 2,2,3,3,4,4,4-heptafluoro-butyl methacrylate, and the like.
Examples of the acrylamide compound include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-benzylacrylamide, N-phenylacrylamide, and N, N-dimethylacrylamide.

Examples of the raw material monomer of the polymethacrylic acid amide compound include methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, N-benzyl methacrylamide, N-phenyl methacrylamide, and N, N-dimethyl methacrylamide. .
Examples of the raw material monomer for the polyvinyl compound include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether.
Examples of the raw material monomer for the polystyrene compound include styrene, methylstyrene, chlorostyrene, bromostyrene, and hydroxystyrene.
Examples of the raw material monomer for the polymaleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

  These polymers are produced by dissolving an addition polymerizable monomer and an optionally added chain transfer agent (10% or less based on the mass of the monomer) in an organic solvent, and then adding a polymerization initiator to perform a polymerization reaction. Thereafter, it can be produced by adding a polymerization terminator. The addition amount of the polymerization initiator is 1 to 10% with respect to the mass of the monomer, and the addition amount of the polymerization terminator is 0.01 to 0.2% by mass. Examples of the organic solvent used include propylene glycol monomethyl ether, propylene glycol monopropyl ether, ethyl lactate, cyclohexanone, methyl ethyl ketone, and dimethylformamide, chain transfer agents such as dodecane thiol and dodecyl thiol, and polymerization initiators such as azo Examples thereof include bisisobutyronitrile and azobiscyclohexanecarbonitrile, and examples of the polymerization terminator include 4-methoxyphenol. The reaction temperature is appropriately selected from 30 to 100 ° C., and the reaction time is appropriately selected from 1 to 48 hours.

The resist underlayer film forming composition of the present invention can contain a crosslinking agent component. Examples of the cross-linking agent include melamine type, substituted urea type, or polymer type thereof. Preferably, a cross-linking agent having at least two cross-linking substituents, methoxymethylated glycoluril, butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzogwanamine, butoxymethylated benzogwanamine, Compounds such as methoxymethylated urea, butoxymethylated urea, methoxymethylated thiourea, or methoxymethylated thiourea. Moreover, the condensate of these compounds can also be used.

Moreover, as the crosslinking agent, a crosslinking agent having high heat resistance can be used. As the crosslinking agent having high heat resistance, a compound containing a crosslinking-forming substituent having an aromatic ring (for example, a benzene ring or a naphthalene ring) in the molecule can be preferably used.
Examples of this compound include a compound having a partial structure of the following formula (2) and a polymer or oligomer having a repeating unit of the following formula (3).
In formula (2), R ₁₀ and R ₁₁ are each a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, n10 is an integer of 1 to 4, and n11 is 1 To (5-n10), and (n10 + n11) represents an integer of 2 to 5.
In Formula (3), R ₁₂ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ₁₃ is an alkyl group having 1 to 10 carbon atoms, n12 is an integer of 1 to 4, and n13 is 0. To (4-n12), and (n12 + n13) represents an integer of 1 to 4. The oligomer and polymer can be used in the range of 2 to 100 or 2 to 50 repeating unit structures.
These alkyl groups and aryl groups can exemplify the above alkyl groups and aryl groups.

The compounds of formula (2) and formula (3), polymers and oligomers are exemplified below.

The above compounds can be obtained as products of Asahi Organic Materials Co., Ltd. and Honshu Chemical Industry Co., Ltd. For example, among the above crosslinking agents, the compound of the formula (3-21) can be obtained as Asahi Organic Materials Co., Ltd., trade name TM-BIP-A.
The addition amount of the crosslinking agent varies depending on the coating solvent to be used, the base substrate to be used, the required solution viscosity, the required film shape, etc., but is 0.001 to 80% by mass with respect to the total solid content, preferably It can be used at 0.01 to 50 mass%, more preferably 0.05 to 40 mass%. These cross-linking agents may cause a cross-linking reaction by self-condensation, but when a cross-linkable substituent is present in the above-mentioned polymer of the present invention, it can cause a cross-linking reaction with those cross-linkable substituents.
In the present invention, as a catalyst for promoting the crosslinking reaction, p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid It is possible to mix acidic compounds such as acids or / and thermal acid generators such as 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and other organic sulfonic acid alkyl esters. I can do it. A compounding quantity can be 0.0001-20 mass% with respect to a total solid, Preferably it is 0.0005-10 mass%, Preferably it can be 0.01-3 mass%.

In the coating type lower layer film forming composition for lithography of the present invention, a photoacid generator can be added in order to match the acidity with the photoresist coated on the upper layer in the lithography process. Preferred photoacid generators include, for example, onium salt photoacid generators such as bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, and phenyl-bis (trichloromethyl) -s. -Halogen-containing compound photoacid generators such as triazine, and sulfonic acid photoacid generators such as benzoin tosylate and N-hydroxysuccinimide trifluoromethanesulfonate. The said photo-acid generator is 0.2-10 mass% with respect to the total solid, Preferably it is 0.4-5 mass%.

In addition to the above, further light absorbers, rheology modifiers, adhesion aids, surfactants, and the like can be added to the resist underlayer film material for lithography of the present invention as necessary.
Examples of further light absorbers include commercially available light absorbers described in “Technical dye technology and market” (published by CMC) and “Dye Handbook” (edited by the Society of Synthetic Organic Chemistry), such as C.I. I. Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114 and 124; C.I. I. Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72 and 73; C.I. I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; I. Disperse Violet 43; C.I. I. Disperse Blue 96; C.I. I. Fluorescent Brightening Agents 112, 135 and 163; C.I. I. Solvent Orange 2 and 45; C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49; I. Pigment Green 10; C.I. I. Pigment Brown 2 etc. can be used suitably. The above light-absorbing agent is usually blended at a ratio of 10% by mass or less, preferably 5% by mass or less, based on the total solid content of the resist underlayer film material for lithography.

  The rheology modifier mainly improves the fluidity of the resist underlayer film forming composition, and improves the film thickness uniformity of the resist underlayer film and the fillability of the resist underlayer film forming composition inside the hole, particularly in the baking process. It is added for the purpose of enhancing. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; Mention may be made of maleic acid derivatives such as normal butyl maleate, diethyl maleate and dinonyl maleate, oleic acid derivatives such as methyl oleate, butyl oleate and tetrahydrofurfuryl oleate, or stearic acid derivatives such as normal butyl stearate and glyceryl stearate. it can. These rheology modifiers are usually blended at a ratio of less than 30% by mass with respect to the total solid content of the resist underlayer film material for lithography.

The adhesion assistant is added mainly for the purpose of improving the adhesion between the substrate or the resist and the resist underlayer film forming composition, and preventing the resist from peeling particularly during development. Specific examples include chlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, chloromethyldimethylchlorosilane, trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane, Alkoxysilanes such as enyltriethoxysilane, hexamethyldisilazane, N, N'-bis (trimethylsilyl) urea, silazanes such as dimethyltrimethylsilylamine, trimethylsilylimidazole, vinyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ- Silanes such as aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, benzotriazole, benzimidazole , Indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, mercaptopyrimidine, etc., 1,1-dimethylurea, 1,3-dimethylurea, etc. And urea or thiourea compounds. These adhesion assistants are usually blended in a proportion of less than 5% by mass, preferably less than 2% by mass, based on the total solid content of the resist underlayer film material for lithography.

  In the resist underlayer film material for lithography of the present invention, a surfactant can be blended in order to further improve the applicability to surface unevenness without generating pinholes or installations. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene nonyl Polyoxyethylene alkyl allyl ethers such as phenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Sorbitan fatty acid esters such as rate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sol Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as tan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, EFTTOP EF301, EF303, EF352 (Trade name, manufactured by Tochem Products Co., Ltd.), MegaFuck F171, F173, R-30 (trade name, manufactured by Dainippon Ink Co., Ltd.), Florard FC430, FC431 (trade name, manufactured by Sumitomo 3M Limited) Fluorine surfactants such as Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (trade name, manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341 (Shin-Etsu) Mention may be made of the academic Kogyo Co., Ltd.), and the like. The blending amount of these surfactants is usually 2.0% by mass or less, preferably 1.0% by mass or less, based on the total solid content of the resist underlayer film material for lithography of the present invention. These surfactants may be added alone or in combination of two or more.

In the present invention, the solvent for dissolving the polymer and the crosslinking agent component, the crosslinking catalyst and the like include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-hydroxypropionic acid Ethyl, 2-hydroxy-2 Ethyl methyl propionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, pyruvate Methyl, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate and the like can be used. These organic solvents are used alone or in combination of two or more.
Furthermore, high boiling point solvents such as propylene glycol monobutyl ether and propylene glycol monobutyl ether acetate can be mixed and used. Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, cyclohexanone and the like are preferable for improving the leveling property.

  The resist used in the present invention is a photoresist or an electron beam resist.

  As the photoresist applied to the upper part of the resist underlayer film for lithography in the present invention, either negative type or positive type can be used, and a positive type photoresist composed of a novolak resin and 1,2-naphthoquinonediazide sulfonic acid ester, depending on the acid. Chemically amplified photoresist comprising a binder having a group that decomposes to increase the alkali dissolution rate and a photoacid generator, a low molecular weight compound and photoacid that increases the alkali dissolution rate of the photoresist by decomposition with an alkali-soluble binder and acid Chemically amplified photoresist comprising a generator, comprising a binder having a group that decomposes with acid to increase the alkali dissolution rate, a low-molecular compound that decomposes with acid to increase the alkali dissolution rate of the photoresist, and a photoacid generator Chemically amplified photoresist with Si atoms in the skeleton That there is a photoresist or the like, for example, Rohm & Hearts Co., Ltd., and trade name APEX-E.

  The electron beam resist applied on the upper part of the resist underlayer film for lithography in the present invention, for example, generates an acid by irradiation with a resin containing an Si-Si bond in the main chain and an aromatic ring at the terminal and an electron beam. A composition comprising an acid generator or a composition comprising a poly (p-hydroxystyrene) having a hydroxyl group substituted with an organic group containing N-carboxyamine and an acid generator that generates an acid upon irradiation with an electron beam It is done. In the latter electron beam resist composition, the acid generated from the acid generator by electron beam irradiation reacts with the N-carboxyaminoxy group of the polymer side chain, and the polymer side chain decomposes into a hydroxyl group to show alkali solubility and an alkali developer. To form a resist pattern. Acid generators that generate acid upon irradiation with electron beams are 1,1-bis [p-chlorophenyl] -2,2,2-trichloroethane and 1,1-bis [p-methoxyphenyl] -2,2,2. -Halogenated organic compounds such as trichloroethane, 1,1-bis [p-chlorophenyl] -2,2-dichloroethane, 2-chloro-6- (trichloromethyl) pyridine, triphenylsulfonium salts, diphenyliodonium salts, etc. Examples thereof include sulfonic acid esters such as onium salts, nitrobenzyl tosylate, and dinitrobenzyl tosylate.

As a resist developer having a resist underlayer film formed using the resist underlayer film material for lithography of the present invention, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, etc. Inorganic amines, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, dimethylethanolamine and triethanolamine Alcohol aqueous solutions such as alcohol amines, quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, and cyclic amines such as pyrrole and piperidine can be used. Furthermore, an appropriate amount of an alcohol such as isopropyl alcohol or a nonionic surfactant may be added to the alkaline aqueous solution. Of these, preferred developers are quaternary ammonium salts, more preferably tetramethylammonium hydroxide and choline.

Next, the resist pattern forming method of the present invention will be described. A spinner, a coater, etc. are suitably used on a substrate (for example, a transparent substrate such as a silicon / silicon dioxide coating, a glass substrate, an ITO substrate) used for manufacturing a precision integrated circuit device. After applying the resist underlayer film forming composition by a simple coating method, it is baked and cured to form a coating type underlayer film. Here, the film thickness of the resist underlayer film is preferably 0.01 to 3.0 μm. Moreover, as conditions for baking after application | coating, it is 0.5 to 120 minutes at 80-350 degreeC. Then, directly or on the resist underlayer film, if necessary, coat one or several layers of coating material on the resist underlayer film, then apply the resist, and irradiate with light or electron beam through a predetermined mask. A good resist pattern can be obtained by developing, rinsing and drying. If necessary, post-irradiation heating (PEB: Post Exposure Bake) can be performed. Then, the resist underlayer film where the resist has been developed and removed by the above process is removed by dry etching, and a desired pattern can be formed on the substrate.
The exposure light in the photoresist is actinic radiation such as near ultraviolet, far ultraviolet, or extreme ultraviolet (for example, EUV, wavelength 13.5 nm), for example, 248 nm (KrF laser light), 193 nm (ArF laser light), Light having a wavelength such as 157 nm (F ₂ laser light) is used. The light irradiation can be used without particular limitation as long as it is a method capable of generating an acid from a photoacid generator, and the exposure amount is 1 to 2000 mJ / cm ² , or 10 to 1500 mJ / cm ² , or 50. According to ~ 1000 mJ / cm ² .
Moreover, the electron beam irradiation of an electron beam resist can be performed using an electron beam irradiation apparatus, for example.

In the present invention, a step of forming the resist underlayer film on the semiconductor substrate with the resist underlayer film forming composition, a step of forming a resist film thereon, a step of forming a resist pattern by light or electron beam irradiation and development, a resist pattern Thus, a semiconductor device can be manufactured through a step of etching the resist underlayer film and a step of processing the semiconductor substrate with the patterned resist underlayer film.
In the future, as the miniaturization of the resist pattern proceeds, there arises a problem of resolution and a problem that the resist pattern collapses after development, and it is desired to reduce the thickness of the resist. For this reason, it is difficult to obtain a resist pattern film thickness sufficient for substrate processing, and not only the resist pattern but also the resist underlayer film formed between the resist and the semiconductor substrate to be processed functions as a mask during substrate processing. The process to have it has become necessary. Unlike conventional high-etch-rate resist underlayer films, the resist underlayer film for lithography, which has a selection ratio of dry etching rates close to that of resist, is selected as a resist underlayer film for such processes, and a lower dry etching rate than resist. There has been a growing demand for a resist underlayer film for lithography having a higher ratio and a resist underlayer film for lithography having a lower dry etching rate selection ratio than a semiconductor substrate. Further, such a resist underlayer film can be provided with an antireflection ability, and can also have a function of a conventional antireflection film.

  On the other hand, in order to obtain a fine resist pattern, a process of making the resist pattern and the resist underlayer film narrower than the pattern width at the time of developing the resist during dry etching of the resist underlayer film has begun to be used. Unlike the conventional high etch rate antireflection film, a resist underlayer film having a selectivity of a dry etching rate close to that of the resist has been required as a resist underlayer film for such a process. Further, such a resist underlayer film can be provided with an antireflection ability, and can also have a function of a conventional antireflection film.

  In the present invention, after forming the resist underlayer film of the present invention on the substrate, directly or on the resist underlayer film as needed, after forming one to several layers of coating material on the resist underlayer film, A resist can be applied. As a result, the pattern width of the resist becomes narrow, and even when the resist is thinly coated to prevent pattern collapse, the substrate can be processed by selecting an appropriate etching gas.

  That is, a step of forming the resist underlayer film on the semiconductor substrate with the resist underlayer film forming composition, and forming a hard mask by a coating material containing a silicon component or the like or a hard mask (for example, silicon nitride oxide) on the semiconductor substrate. A step of forming a resist film thereon, a step of forming a resist pattern by light and electron beam irradiation and development, a step of etching the hard mask with a halogen-based gas using the resist pattern, and a patterned hard mask Thus, a semiconductor device can be manufactured through a step of etching the resist underlayer film with an oxygen-based gas or a hydrogen-based gas and a step of processing a semiconductor substrate with a halogen-based gas with the patterned resist underlayer film.

  When considering the effect as an antireflection film, the resist underlayer film forming composition for lithography of the present invention has a light absorption site incorporated into the skeleton, so there is no diffused material in the photoresist during heating and drying. Moreover, since the light absorption site has a sufficiently large light absorption performance, the effect of preventing reflected light is high.

  The composition for forming a resist underlayer film for lithography of the present invention has high thermal stability, can prevent contamination of the upper layer film by decomposition products during baking, and can provide a margin for the temperature margin of the baking process. is there.

  Furthermore, the resist underlayer film material for lithography according to the present invention has a function of preventing reflection of light depending on process conditions, and further prevents the interaction between the substrate and the photoresist, or a material or photoresist used for the photoresist. The film can be used as a film having a function of preventing an adverse effect on a substrate of a substance generated during exposure.

(Preparation of raw materials) Synthesis of trihydroxynaphthalene In a 500 ml eggplant flask, 15.0 g (86.1 mmol) of 5-hydroxy-1,4-naphthoquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), 150 g of ethyl acetate (manufactured by Kanto Chemical), 29.9 g (129.2 mmol) of sodium dithionite (manufactured by Kanto Kagaku) dissolved in 150 g of pure water was added and stirred at 25 ° C. for 20 hours. The aqueous phase was removed from the reaction solution, washed with pure water, and then ethyl acetate was removed with an evaporator to obtain 14.29 g (81.1 mmol) of 1,4,5-trihydroxynaphthalene as a brown solid. Got as.
¹ H-NMR (500 MHz, DMSO-d ₆ ): 6.55 ppm (d, 1 H), 6.65 ppm (d, 1 H), 6.71 ppm (d, 1 H), 7.22 ppm (t, 1 H), 7 .50 ppm (d, 1H), 9.33 ppm (s, 1H), 10.32 ppm (s, 1H), 10.69 ppm (s, 1H)

Synthesis example 1
In a 50 ml eggplant flask, 0.90 g of 1,4,5-trihydroxynaphthalene, 0.78 g of 1-naphthaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.061 g of methanesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), propylene glycol 2.63 g of monomethyl ether was added. Thereafter, the mixture was heated to 0 ° C. and stirred at reflux for about 14 hours. After completion of the reaction, the reaction mixture was diluted with 3.00 g of tetrahydrofuran (manufactured by Kanto Chemical), and the precipitate was removed by filtration. The solution was dropped into the collected hexane solution and reprecipitated. The obtained precipitate was suction filtered, and the filtrate was dried under reduced pressure at 85 ° C. overnight. And 1.26g of 1,4,5-trihydroxynaphthalene resin of amber powder was obtained. The obtained polymer corresponded to Formula (1-11). The weight average molecular weight measured in terms of polystyrene by GPC was Mw 2,200, and the polydispersity Mw / Mn was 1.75.

Synthesis example 2
In a 50 ml eggplant flask, 0.88 g of 1,4,5-trihydroxynaphthalene, 1.62 g of 1-pyrenecarboxaldehyde (manufactured by Aldrich), 10.52 g of 1,4-dioxane (manufactured by Kanto Chemical), one p-toluenesulfonic acid Hydrate (Tokyo Chemical Industry Co., Ltd.) 0.14g was put. Thereafter, the mixture was heated to 110 ° C. and stirred at reflux for about 16 hours. After completion of the reaction, the reaction mixture was diluted with 5.26 g of tetrahydrofuran (manufactured by Kanto Chemical), and the precipitate was removed by filtration. The solution was dropped into the collected hexane solution and reprecipitated. The obtained precipitate was suction filtered, and the filtrate was dried under reduced pressure at 85 ° C. overnight. And 1.48g of 1,4,5-trihydroxynaphthalene resin of amber powder was obtained. The obtained polymer corresponded to Formula (1-41). The weight average molecular weight Mw measured in terms of polystyrene by GPC was 1,500, and the polydispersity Mw / Mn was 1.54.

Synthesis example 3
In a 50 ml eggplant flask, 0.84 g of 1,4,5-trihydroxynaphthalene, 0.81 g of 1-pyrenecarboxaldehyde (manufactured by Aldrich), 0.55 g of 1-naphthaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.), 1,4- 7.31 g of dioxane (manufactured by Kanto Chemical) and 0.14 g of p-toluenesulfonic acid monohydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) were added. Thereafter, the mixture was heated to 110 ° C. and stirred at reflux for about 16 hours. After completion of the reaction, the reaction mixture was diluted with 4.74 g of tetrahydrofuran (manufactured by Kanto Chemical), and the precipitate was removed by filtration. The solution was dropped into the recovered methanol / water mixed solution and reprecipitated. The obtained precipitate was suction filtered, and the filtrate was dried under reduced pressure at 85 ° C. overnight. And 1.28g of 1,4,5-trihydroxynaphthalene resin of amber powder was obtained. The obtained polymer corresponded to Formula (1-46). The weight average molecular weight Mw measured in terms of polystyrene by GPC was 2,500, and the polydispersity Mw / Mn was 1.67.

Comparative Synthesis Example 1
In a 100 ml eggplant flask, 11.21 g of 1,5-dihydroxynaphthalene, 5.48 g of 1-naphthaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.), 45.04 g of 1,4-dioxane (manufactured by Kanto Chemical), one p-toluenesulfonic acid 1.34 g of hydrate (Tokyo Chemical Industry Co., Ltd.) was added. Thereafter, the mixture was heated to 110 ° C. and stirred at reflux for about 23 hours. After completion of the reaction, the reaction mixture was diluted with 22.5 g of tetrahydrofuran (manufactured by Kanto Chemical), and the precipitate was removed by filtration. The solution was dropped into the recovered methanol / water mixed solution and reprecipitated. The obtained precipitate was suction filtered, and the filtrate was dried under reduced pressure at 85 ° C. overnight. And 8.03g of 1,5-dihydroxynaphthalene resin of amber powder was obtained. The obtained polymer corresponded to Formula (3-1). The weight average molecular weight Mw measured in terms of polystyrene by GPC was 1,900, and the polydispersity Mw / Mn was 1.35.

Comparative Synthesis Example 2
In a 200 ml three-necked flask, 10.09 g of phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd.), 18.42 g of 1-pyrenecarboxaldehyde (manufactured by Aldrich), 49.61 g of 1,4-dioxane (manufactured by Kanto Chemical), p-toluenesulfone 4.56 g of acid monohydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added. Thereafter, the mixture was heated to 110 ° C. and stirred at reflux for about 5 hours. After completion of the reaction, the reaction mixture was diluted with 24.80 g of tetrahydrofuran (manufactured by Kanto Chemical), and the precipitate was removed by filtration. The collected filtrate was dropped into a methanol / water mixed solution and reprecipitated. The obtained precipitate was suction filtered, and the filtrate was dried under reduced pressure at 85 ° C. overnight. And 25.26g of phloroglucinol resin of the brown powder was obtained. The obtained polymer corresponded to Formula (3-2). The weight average molecular weight Mw measured by GPC in terms of polystyrene was 2,800, and the polydispersity Mw / Mn was 2.18.

Example 1
Forming a resist underlayer film for use in a lithography process with a multilayer film by dissolving in 1 g of the resin obtained in Synthesis Example 1 in 1.15 g of propylene glycol monomethyl ether acetate, 1.15 g of propylene glycol monomethyl ether and 9.19 g of cyclohexanone A solution of the composition was prepared.
Example 2
Forming a resist underlayer film for use in a lithography process with a multilayer film by dissolving in 1 g of the resin obtained in Synthesis Example 2 in 1.15 g of propylene glycol monomethyl ether acetate, 1.15 g of propylene glycol monomethyl ether and 9.19 g of cyclohexanone A solution of the composition was prepared.
Example 3
Forming a resist underlayer film for use in a lithography process with a multilayer film by dissolving in 1 g of the resin obtained in Synthesis Example 3 in 1.15 g of propylene glycol monomethyl ether acetate, 1.15 g of propylene glycol monomethyl ether and 9.19 g of cyclohexanone A solution of the composition was prepared.

Comparative Example 1
1 g of cresol novolak resin (commercial product, weight average molecular weight 4000) was dissolved in 10.34 g of propylene glycol monomethyl ether and 2.59 g of cyclohexanone to prepare a solution of a resist underlayer film forming composition used in a lithography process using a multilayer film. .
Comparative Example 2
Lithium-based lithography by dissolving 2 g of the resin (Formula 3-1) obtained in Comparative Synthesis Example 1 in 9.19 g of propylene glycol monomethyl ether acetate, 9.19 g of propylene glycol monomethyl ether, and 4.59 g of cyclohexanone. A resist underlayer film forming composition solution used in the process was prepared.
Comparative Example 3
In 1 g of the resin (Formula 3-2) obtained in Comparative Synthesis Example 2, 1034 g of propylene glycol monomethyl ether and 2.59 g of cyclohexanone are dissolved to prepare a solution of a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Measurement of optical parameters)
The resist underlayer film solutions prepared in Examples 1 to 3 and Comparative Example 1 were applied onto a silicon wafer using a spin coater. A resist underlayer film (film thickness 0.05 μm) was formed on a hot plate at 400 ° C. for 2 minutes (in Comparative Example 1, 205 ° C. for 1 minute). These resist underlayer films were measured for refractive index (n value) and optical extinction coefficient (also called k value, attenuation coefficient) at a wavelength of 193 nm using a spectroscopic ellipsometer. The results are shown in Table 1.

[Table 1]
Table 1 Refractive index n and optical extinction coefficient k
―――――――――――――――――――――――――――――――
n k
(193 nm)
Example 1 250 ° C. Firing Film 1.41 0.33
Example 1 Fired film at 400 ° C. 1.39 0.43
Example 2 240 degreeC baking film 1.57 0.49
Example 2 Fired film at 400 ° C. 1.43 0.48
Example 3 240 ° C. fired film 1.48 0.45
Example 3 Fired film at 400 ° C. 1.42 0.46
Comparative Example 1 400 ° C. Firing Film 1.53 0.42
―――――――――――――――――――――――――――――――

(Elution test for photoresist solvent)
The resist underlayer film forming composition solutions prepared in Examples 1 to 3 were applied on a silicon wafer using a spin coater. Baking was performed on a hot plate at 240 ° C. for 1 minute or at 400 ° C. for 2 minutes to form a resist underlayer film (film thickness 0.20 μm). The resist underlayer film was subjected to an immersion test in a solvent used for the resist, such as ethyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and cyclohexanone.
It was confirmed that the films obtained by baking the solutions of Examples 1 to 3 at 240 ° C. for 1 minute were insoluble in these solvents.

(Measurement of dry etching rate)
The following etchers and etching gases were used to measure the dry etching rate.
RIE-10NR (manufactured by Samco): CF ₄
The resist underlayer film forming composition solutions prepared in Examples 1 to 3 and Comparative Example 1 were applied on a silicon wafer using a spin coater. (Comparative Example 1 was baked at 205 ° C. for 1 minute to form a resist underlayer film (film thickness: 0.20 μm). CF ₄ gas was used as an etching gas. Used to measure the dry etching rate.
Moreover, the coating film was formed on the silicon wafer using the solution of the comparative example 1 using the spin coater. The dry etching rate was measured using CF ₄ gas as an etching gas, and compared with the dry etching rates of the resist underlayer films of Examples 1 to 3. The results are shown in Table 2. The speed ratio (1) is a dry etching speed ratio of (each dry etching speed of the resist underlayer film used in Examples 1 to 3) / (dry etching speed of Comparative Example 1).

[Table 2] Dry etching rate ratio -----------
Example 1 250 ° C. Firing Film Speed Ratio (1) 1.01
Example 1 400 ° C. Firing Film Speed Ratio (1) 1.03
Example 2 240 ° C. Firing Film Speed Ratio (1) 1.04
Example 2 400 ° C. Firing Film Speed Ratio (1) 0.97
Example 3 240 ° C. fired film speed ratio (1) 0.97
Example 3 400 ° C. Firing Film Speed Ratio (1) 1.01
――――――――――――――――――――――――――――――――――

(Measurement of pattern bending resistance)
The solutions of the resist underlayer film forming compositions prepared in Examples 2 to 3 and Comparative Examples 2 to 3 were each applied onto a silicon wafer with a silicon oxide film using a spin coater. A resist underlayer film (film thickness 200 nm) was formed by baking on a hot plate at 240 ° C. for 1 minute or 400 ° C. for 2 minutes. A silicon hard mask forming composition solution (polyorganosiloxane solution) was applied on the resist underlayer film and baked at 240 ° C. for 1 minute to form a silicon hard mask layer (polyorganosiloxane condensate, film thickness 45 nm). A resist solution was applied thereon and baked at 100 ° C. for 1 minute to form a resist layer (film thickness 120 nm). Exposure was performed using a mask at a wavelength of 193 nm, post-exposure heating PEB (1 minute at 105 ° C.) was performed, and development was performed to obtain a resist pattern. Thereafter, dry etching was performed with a fluorine-based gas (component is CF ₄ ), and the resist pattern was transferred to a hard mask. Thereafter, dry etching was performed with an oxygen-based gas (component is O ₂ ), and the resist pattern was transferred to the resist underlayer film. Thereafter, dry etching was performed with a fluorine-based gas (component is C ₄ F ₈ ) to remove the silicon oxide film on the silicon wafer. Each pattern shape at that time was observed with an electron microscope.

As the pattern width narrows, irregular pattern bending called wiggling is likely to occur. However, the above-described steps are performed using the resist underlayer film forming composition of the above-described embodiment, and pattern wiggling occurs. The starting pattern width was observed with an electron microscope.
Since the processing of the substrate based on the faithful pattern becomes impossible due to the occurrence of pattern bending, it is necessary to process the substrate with the pattern width (limit pattern width) immediately before the occurrence of the pattern bending. The narrower the limit pattern width at which pattern bending starts to occur, the finer the substrate can be processed.
A length-measuring scanning electron microscope (manufactured by Hitachi, Ltd.) was used for measuring the resolution. The measurement results are shown in Table 3.

[Table 3]
Table 3 Limit pattern width at which pattern bending starts to occur (fired at 240 ° C. for 2 minutes)
――――――――――――――――――――――――――――――――――――
(When the resist underlayer film forming composition of Example 2 is used) 38.5 nm
(When the resist underlayer film forming composition of Example 3 is used) 36.0 nm
(When the resist underlayer film forming composition of Comparative Example 2 is used) 39.5 nm
――――――――――――――――――――――――――――――――――――

[Table 4]
Table 4 Limit pattern width at which pattern bending starts to occur (firing at 400 ° C. for 2 minutes)
――――――――――――――――――――――――――――――――――――
(When the resist underlayer film forming composition of Example 2 is used) 38.4 nm
(When the resist underlayer film forming composition of Example 3 is used) 36.2 nm
(When the resist underlayer film forming composition of Comparative Example 2 is used) 38.2 nm
(When the resist underlayer film forming composition of Comparative Example 3 is used) 40.8 nm
――――――――――――――――――――――――――――――――――――

Unlike the conventional high etch rate antireflection film, the resist underlayer film material used in the lithography process using the multilayer film of the present invention is close to the photoresist or has a lower dry etching rate selection ratio than the photoresist. It is possible to provide a resist underlayer film that has a lower dry etching rate selection ratio and can also have an effect as an antireflection film. It was also found that the lower layer film material of the present invention has heat resistance capable of forming a hard mask on the upper layer by vapor deposition. Further, even when the firing temperature is low, it is difficult to generate pattern bending, and a good pattern can be obtained. With a pattern width of at least around 36 nm, a good pattern without bending can be obtained.

Claims (11)

Formula (1):

(In the formula (1), A is a hydroxy group-substituted naphthylene group derived from polyhydroxynaphthalene, has 3 hydroxy groups, and B is a monovalent condensed aromatic carbonized with 2 to 4 benzene rings condensed. A composition for forming a resist underlayer film for lithography, comprising a polymer comprising a unit structure of a hydrogen ring group. The resist underlayer film forming composition according to claim 1, wherein A is a hydroxy-substituted naphthylene group derived from trihydroxynaphthalene. The resist underlayer film forming composition according to claim 1, wherein the condensed aromatic hydrocarbon ring group of B is a naphthalene ring group, an anthracene ring group, or a pyrene ring group. The condensed aromatic hydrocarbon ring group of B has a halogen group, a hydroxyl group, a nitro group, an amino group, a carboxyl group, a carboxylic acid ester group, a nitrile group, or a combination thereof as a substituent. Item 4. The resist underlayer film forming composition according to any one of Items 3 above. The resist underlayer film forming composition according to any one of claims 1 to 4, further comprising a crosslinking agent. The resist underlayer film forming composition according to any one of claims 1 to 5, further comprising an acid and / or an acid generator. A resist underlayer film obtained by applying the resist underlayer film forming composition according to claim 1 onto a semiconductor substrate and baking the composition. A method for forming a resist pattern, which is used for manufacturing a semiconductor, comprising a step of applying the resist underlayer film forming composition according to any one of claims 1 to 6 on a semiconductor substrate and baking the composition to form an underlayer film. . A step of forming a lower layer film on the semiconductor substrate with the resist underlayer film forming composition according to any one of claims 1 to 6, a step of forming a resist film thereon, light or electron beam irradiation, A method for manufacturing a semiconductor device, comprising: a step of forming a resist pattern by development; a step of etching the lower layer film with a resist pattern; and a step of processing a semiconductor substrate with a patterned lower layer film. A step of forming an underlayer film with the resist underlayer film forming composition according to any one of claims 1 to 6 on a semiconductor substrate, a step of forming a hard mask thereon, and further forming a resist film thereon A step of forming a resist pattern by irradiation and development of light or electron beam, a step of etching a hard mask with the resist pattern, a step of etching the lower layer film with a patterned hard mask, and a patterned lower layer A method for manufacturing a semiconductor device, comprising a step of processing a semiconductor substrate with a film. The manufacturing method according to claim 10, wherein the hard mask is formed by an inorganic coating or an inorganic vapor deposition.