JP7255589B2 - Composition for forming resist underlayer film, resist underlayer film, method for forming same, and method for forming pattern - Google Patents

Description

The present invention relates to a composition for forming a resist underlayer film, a resist underlayer film, a method for forming the same, and a pattern forming method.

In the manufacture of semiconductor devices, for example, a multilayer resist process is used in which a resist pattern is formed by exposing and developing a resist film laminated on a substrate with a resist underlayer such as an organic underlayer film or a silicon-containing film interposed therebetween. . In this process, the resist underlayer film is etched using this resist pattern as a mask, and the substrate is further etched using the obtained resist underlayer film pattern as a mask, thereby forming a desired pattern on the substrate and obtaining a patterned substrate. (See JP-A-2004-177668).

JP-A-2004-177668

The resist underlayer film and the composition for forming the resist underlayer film of the present invention are the above-described organic underlayer film and the composition for forming the same. A resist underlayer film-forming composition used for forming an organic underlayer film in a multilayer resist process is required to have good coatability, and the resist underlayer film (organic underlayer film) formed is required to have excellent heat resistance and etching resistance. Excellent resistance is required. In addition, in a multilayer resist process, it is necessary to be excellent in suppressing the occurrence of defects such as cracks and peeling on the surface of the silicon-containing film, that is, to be excellent in suppressing film defects of the silicon-containing film.

The present invention has been made based on the circumstances as described above, and an object of the present invention is to provide a composition for forming a resist underlayer film capable of forming a resist underlayer film having excellent heat resistance, etching resistance and film defect suppressing properties, and a resist underlayer. An object of the present invention is to provide a film, a method for forming a resist underlayer film, and a method for forming a pattern.

（式（１）中、Ｒ^１は、置換又は非置換の炭素数１～７０のｎ価の炭化水素基である。Ｒ^３及びＲ^４は、それぞれ独立して、置換若しくは非置換の炭素数１～２０の１価の炭化水素基若しくは水素原子であるか、又はＲ^３及びＲ^４が互いに合わせられこれらが結合する窒素原子と共に構成される環員数３～２０の環構造の一部である。但し、Ｒ^１、Ｒ^３及びＲ^４の少なくとも１つは、芳香環を有し、この芳香環の炭素原子で上記式（１）中の窒素原子に結合する基である。ｎは、１～１０の整数である。ｎが２以上の場合、複数のＲ^３は同一又は異なり、複数のＲ^４は同一又は異なる。
式（２）中、Ｒ^２’は、置換若しくは非置換の炭素数１～２０の２価の炭化水素基である。Ｒ^３’は、置換若しくは非置換の炭素数１～２０の１価の炭化水素基又は水素原子である。但し、Ｒ^２’及びＲ^３’の少なくとも１つは、芳香環を有し、この芳香環の炭素原子で上記式（２）中の窒素原子に結合する基である。ｍは、１～１０の整数である。ｍが２以上の場合、複数のＲ^２’は同一又は異なり、複数のＲ^３’は同一又は異なる。）The invention made to solve the above problems is a compound having an aromatic ring and a nitrogen atom bonded to a carbon atom of this aromatic ring (hereinafter also referred to as "[A] compound"), a solvent (hereinafter referred to as "[B ] solvent”), and the above [A] compound is a composition for forming a resist underlayer film represented by the following formula (1) or (2).

(In formula (1), R ¹ is a substituted or unsubstituted n-valent hydrocarbon group having 1 to 70 carbon atoms. R ³ and R ⁴ each independently represent a substituted or unsubstituted carbon number 1 to 20 monovalent hydrocarbon groups or hydrogen atoms, or part of a 3 to 20 ring-membered ring structure in which R ³ and R ⁴ are taken together and formed together with the nitrogen atom to which they are attached; provided that at least one of R ¹ , R ³ and R ⁴ is a group having an aromatic ring and being bonded to the nitrogen atom in the above formula (1) through a carbon atom of this aromatic ring, n is 1; It is an integer of up to 10. When n is 2 or more, multiple R ³ are the same or different, and multiple R ⁴ are the same or different.
In formula (2), R ^2′ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. R ^3′ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom. However, at least one of R ^2' and R ^3' is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (2) through a carbon atom of the aromatic ring. m is an integer from 1 to 10; When m is 2 or more, multiple R ^2' are the same or different, and multiple R ^3' are the same or different. )

Another invention made to solve the above problems is a resist underlayer film formed from the composition for forming a resist underlayer film.

Still another invention, which has been made to solve the above problems, comprises the step of directly or indirectly coating a substrate with a composition for forming a resist underlayer film, wherein the composition for forming a resist underlayer film is a compound [A] and [B] a method for forming a resist underlayer film containing a solvent.

Still another invention, which has been made to solve the above problems, comprises a step of directly or indirectly coating a substrate with a composition for forming a resist underlayer film, and directly or indirectly on the resist underlayer film formed by the coating step A pattern forming method comprising a step of indirectly forming a resist pattern and a step of performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains a compound [A] and a solvent [B]. is.

The composition for forming a resist underlayer film of the present invention can form a resist underlayer film that is excellent in heat resistance, etching resistance, and film defect suppressing properties. The resist underlayer film of the present invention is excellent in heat resistance, etching resistance and film defect suppressing property. According to the method for forming a resist underlayer film of the present invention, a resist underlayer film having excellent heat resistance, etching resistance, and film defect suppressing properties can be formed. According to the pattern forming method of the present invention, a patterned substrate having a favorable pattern shape can be obtained by using such an excellent resist underlayer film. Therefore, these can be suitably used for the manufacture of semiconductor devices, etc., which are expected to be further miniaturized in the future.

<Composition for forming resist underlayer film>
The composition for forming a resist underlayer film (hereinafter also simply referred to as "composition") contains [A] compound and [B] solvent. The composition may contain optional ingredients as long as the effects of the present invention are not impaired. Each component will be described below.

<[A] compound>
[A] compound is a compound represented by the following formula (1) or the following formula (2) (hereinafter, the compound represented by formula (1) is also referred to as "[A1] compound" and is represented by formula (2) (also referred to as "[A2] compound").

In formula (1) above, R ¹ is a substituted or unsubstituted n-valent hydrocarbon group having 1 to 70 carbon atoms. R ³ and R ⁴ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom, or R ³ and R ⁴ are combined and bonded It is part of a 3- to 20-membered ring structure composed together with a nitrogen atom. However, at least one of R ¹ , R ³ and R ⁴ is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (1) through the carbon atom of this aromatic ring. n is an integer from 1 to 10; When n is 2 or more, multiple ^R3 's are the same or different, and multiple ^R4 's are the same or different.

In formula (2) above, R ^2′ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. R ^3′ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom. However, at least one of R ^2' and R ^3' is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (2) through a carbon atom of the aromatic ring. m is an integer from 1 to 10; When m is 2 or more, multiple R ^2' are the same or different, and multiple R ^3' are the same or different.

By containing the [A] compound, the composition can form a resist underlayer film that is excellent in heat resistance, etching resistance, and film defect suppressing properties. Although it is not necessarily clear why the composition has the above-described structure, it can be inferred as follows. That is, the [A] compound has an aromatic ring to which an amino group having a high electron-donating ability is bonded. The [A] compound having such a structure is easily oxidized and easily generates radical active species, and as a result, the composition for forming a resist underlayer film can form a resist underlayer film having denser crosslinks. It is considered that a resist underlayer film having excellent heat resistance, etching resistance, and film defect suppressing property can be formed.
[A1] compound and [A2] compound are described below.

[[A1] compound]
The [A1] compound is a compound represented by the above formula (1).

Examples of n-valent hydrocarbon groups having 1 to 70 carbon atoms represented by R ¹ include alkanes such as methane, ethane, propane and butane, and alkenes such as ethene, propene, butene and pentene. chain hydrocarbons, cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, adamantane, cycloalkenes such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, norbornene, etc. Hydrogen, benzene, toluene, xylene, mesitylene, naphthalene, methylnaphthalene, dimethylnaphthalene, groups obtained by removing n hydrogen atoms from hydrocarbons such as aromatic hydrocarbons having 6 to 70 carbon atoms such as arenes such as anthracene, etc. mentioned.

Examples of substituents of the n-valent hydrocarbon group include halogen atoms such as fluorine, chlorine, bromine and iodine atoms, alkoxy groups such as methoxy, ethoxy and propoxy, methoxycarbonyl and ethoxycarbonyl. Alkoxycarbonyl groups such as groups, methoxycarbonyloxy groups, alkoxycarbonyloxy groups such as ethoxycarbonyloxy groups, acyl groups such as formyl groups, acetyl groups, propionyl groups, butyryl groups, benzoyl groups, cyano groups, nitro groups, etc. be done.

R ¹ is preferably a group containing an aromatic ring (hereinafter also referred to as “group (1)”). As the aromatic ring, an aromatic carbocyclic ring is preferred. Examples of aromatic carbocyclic rings include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyrene ring, tetracene ring, pentacene ring, and fluorene ring.

As group (1), a group in which the nitrogen atom in formula (1) is bonded to the aromatic carbocyclic ring of R ¹ (hereinafter also referred to as “group (1-1)”) is preferable.

Examples of the group (1-1) include groups represented by the following formula (3).

In the above formula (3), Ar ¹ is a group obtained by removing (p+a) hydrogen atoms on an aromatic ring from an arene having 6 to 70 carbon atoms. ^RA is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group or a halogen atom. p is an integer from 0 to 20; When p is 2 or more, multiple ^RAs are the same or different. a is an integer from 1 to 10; * indicates the bonding site with the nitrogen atom in the above formula (1).

Examples of arenes having 6 to 70 carbon atoms that give Ar ¹ include benzene, naphthalene, anthracene, phenanthrene, tetracene, pyrene, biphenyl, dimethylbiphenyl, diphenylbiphenyl and fluorene.

"Organic group" refers to a group containing at least one carbon atom. The monovalent organic group having 1 to 20 carbon atoms represented by R ^A includes, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a divalent heteroatom-containing group between the carbon atoms of the hydrocarbon group. groups, and groups obtained by substituting a monovalent heteroatom-containing group for some or all of the hydrogen atoms of the hydrocarbon group and the group having a divalent heteroatom-containing group.

Divalent heteroatom-containing groups include, for example, -CO-, -CS-, -NH-, -O-, -S-, groups in which these are combined, and the like.

The monovalent heteroatom-containing group includes, for example, a hydroxy group, a sulfanyl group, a cyano group, a nitro group, a halogen atom and the like.

As p, 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is even more preferable.
As a, 1 to 5 are preferable, and 2 or 3 is more preferable.

Examples of the group (1-1) include groups represented by the following formulas.

In the above formula, each R is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. * is synonymous with the above formula (3).

Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R ³ or R ⁴ include alkanes such as methane, ethane, propane and butane, and alkenes such as ethene, propene, butene and pentene. Chain hydrocarbons of 1 to 20 carbon atoms, cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, and adamantane, and cycloalkenes such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, and norbornene, and other fatty acids having 3 to 20 carbon atoms. One hydrogen atom is removed from hydrocarbons such as aromatic hydrocarbons having 6 to 20 carbon atoms such as cyclic hydrocarbons, benzene, toluene, xylene, mesitylene, naphthalene, methylnaphthalene, dimethylnaphthalene, and arenes such as anthracene. and the like.

Examples of the substituents of the monovalent hydrocarbon group for R ³ and R ⁴ include the same groups as those exemplified as the substituents for the n-valent hydrocarbon group for R ¹ above. When the monovalent hydrocarbon group of R ³ and R ⁴ is an aromatic hydrocarbon group, the substituents include alkanes such as methane, ethane, propane and butane, and alkenes such as ethene, propene, butene and pentene. Chain hydrocarbons with 1 to 20 carbon atoms, cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, adamantane and other cycloalkanes, cyclopropene, cyclobutene, cyclopentene, cyclohexene, norbornene and other cycloalkenes with 3 to 3 carbon atoms A group obtained by removing one hydrogen atom from a hydrocarbon of 20 alicyclic hydrocarbons is preferred, and a group obtained by removing one hydrogen atom from an alkane such as methane, ethane, propane and butane is more preferred.

Examples of the 3- to 20-membered ring structure composed of R ³ and R ⁴ include an azacycloalkane structure such as an azacyclopentane structure and an azacyclohexane structure.

at least one of R ³ and R ⁴ is a substituted or unsubstituted monovalent hydrocarbon ^{having 1 to 20 carbon atoms, or R 3 and R 4 are} combined and bonded It is preferably part of a ring structure having 3 to 20 ring members formed with a nitrogen atom, and R ³ and R ⁴ are substituted or unsubstituted monovalent hydrocarbons having 1 to 20 carbon atoms, Alternatively, it is more preferable that R ³ and R ⁴ are combined with each other and be part of a 3- to 20-membered ring structure formed together with the nitrogen atom to which they are attached.

When the monovalent hydrocarbon groups of R ³ and R ⁴ are chain hydrocarbon groups or alicyclic hydrocarbon groups, unsubstituted chain hydrocarbon groups or unsubstituted alicyclic hydrocarbon groups is preferably

At least one of R ¹ , R ³ and R ⁴ has an aromatic ring and is bonded to the nitrogen atom in the above formula (1) through the carbon atom of this aromatic ring.

As a lower limit of n, 2 is preferable. As the upper limit of n, 5 is preferable, and 3 is more preferable.

Examples of [A1] compounds include compounds represented by the following formulas (i1-1) to (i1-10) (hereinafter also referred to as “compounds (i1-1) to (i1-10)”), and the like. .

Among these, compounds (i1-1) to (i1-4) are preferred.

[[A2] compound]
The [A2] compound is a compound represented by the above formula (2).

As the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^2′ , for example, among the groups exemplified as the n-valent hydrocarbon group having 1 to 70 carbon atoms for R ¹ in the above formula (1) , n is 2 and a group having 1 to 20 carbon atoms.

Examples of the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^3′ include the monovalent hydrocarbon groups having 1 to 20 carbon atoms exemplified as R ³ in the above formula (1). and the same groups as above.

The divalent hydrocarbon group for R ^2′ and the substituent for the monovalent hydrocarbon group for R ^3′ include, for example, the groups exemplified as the substituents for the n-valent hydrocarbon group for R 1 in formula (1) above. Similar groups and the like can be mentioned.

R ^2′ is preferably a substituted or unsubstituted divalent hydrocarbon group, more preferably a substituted or unsubstituted arenediyl group.
R ^3′ is preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably an unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.

At least one of R ^2' and R ^3' has an aromatic ring and is bonded to the nitrogen atom in the above formula (2) through a carbon atom of this aromatic ring.

As a lower limit of m, 2 is preferable and 3 is more preferable. The upper limit of m is preferably 6, more preferably 5.

Examples of the [A2] compound include compounds represented by the following formulas (i2-1) to (i2-5) (hereinafter also referred to as “compounds (i2-1) to (i2-5)”), and the like. .

[A] The lower limit of the molecular weight of the compound is preferably 300, more preferably 400, and even more preferably 500. The upper limit of the molecular weight is preferably 4,000, more preferably 2,000, and even more preferably 1,500. By setting the molecular weight of the compound [A] within the above range, the film defect suppressing property of the resist underlayer film can be further improved. [A] compound can be used individually by 1 type or in combination of 2 or more types. When there are two or more [A] compounds, the molecular weight of the [A] compound refers to the number average molecular weight.

[[A] compound synthesis method]
The [A] compound can be synthesized by a known method. The [A1] compound is prepared by, for example, dehydration condensation of an aldehyde compound such as 1-pyrenecarbaldehyde and an aromatic amine compound such as N,N-diethylaniline in the presence of an acid such as sulfuric acid. An aromatic secondary amine compound such as di-p-tolyl-3,3′-dimethylbenzidine and an aromatic halide such as 4-ethyliodobenzene are mixed with copper powder and a base such as potassium carbonate in the presence of 3. A method of group amino grouping, a fluorene compound such as 1,3,5-tri(fluoren-2-yl)benzene and an aldehyde compound such as N,N-dimethylaminobenzaldehyde are combined with an ammonium salt such as tetrabutylammonium bromide. and a method of dehydration condensation in the presence of a base such as sodium hydroxide. The [A2] compound is, for example, a 2- A class amino group-containing azacalixarene compound and an organic halide such as butyl iodide are synthesized in the presence of a base such as 2,6-t-butyl-4-methylpyridine by a method such as tertiary amino grouping. be able to.

[A] The upper limit of the content of hydrogen atoms constituting the compound is preferably 12.0% by mass, more preferably 11.0% by mass, and even more preferably 10.0% by mass. The lower limit of the hydrogen atom content is, for example, 0.1% by mass. By setting the content of hydrogen atoms constituting the [A] compound within the above range, the heat resistance of the resist underlayer film can be further improved. The content of hydrogen atoms constituting the [A] compound is a value calculated from the molecular formula of the [A] compound.

The lower limit of the content of the [A] compound is preferably 50% by mass, more preferably 70% by mass, and even more preferably 85% by mass with respect to all components other than the [B] solvent of the composition. The upper limit of the content ratio is, for example, 100% by mass.

The lower limit of the content of the [A] compound in the composition is preferably 1% by mass, more preferably 3% by mass, and even more preferably 5% by mass. The upper limit of the content ratio is preferably 50% by mass, more preferably 30% by mass, and even more preferably 15% by mass.

<[B] Solvent>
The [B] solvent is not particularly limited as long as it can dissolve or disperse the [A] compound and optionally contained optional components.

[B] Solvents include, for example, alcohol solvents, ketone solvents, ether solvents, ester solvents, and nitrogen-containing solvents. [B] A solvent can be used individually by 1 type or in combination of 2 or more types.

Examples of alcoholic solvents include monoalcoholic solvents such as methanol, ethanol and n-propanol, and polyhydric alcoholic solvents such as ethylene glycol and 1,2-propylene glycol.

Examples of ketone solvents include chain ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and cyclic ketone solvents such as cyclohexanone.

Examples of ether solvents include chain ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether.

Examples of ester solvents include carbonate solvents such as diethyl carbonate, acetic acid monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, diethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate. Valued alcohol partial ether carboxylate solvents, lactate ester solvents such as methyl lactate and ethyl lactate, and the like are included.

Examples of nitrogen-containing solvents include linear nitrogen-containing solvents such as N,N-dimethylacetamide and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[B] The solvent preferably contains an ester solvent or a ketone solvent. As the ester-based solvent, an ester-based solvent having a glycol structure is more preferable from the viewpoint of improving coatability.

Examples of ester solvents having a glycol structure include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate and the like. Among these, propylene glycol monomethyl ether acetate is particularly preferred.

<Optional component>
The composition may contain, as optional components, an oxidizing agent, a cross-linking agent, an acid generator, a surfactant, an adhesion aid, and the like. These arbitrary components can be used individually by 1 type or in combination of 2 or more types.

[Oxidant]
The oxidizing agent is a component that promotes cross-linking of the [A] compound by an oxidation reaction. When the composition contains an oxidizing agent, the cross-linking reaction of the [A] compound is promoted, and the hardness of the formed resist underlayer film can be further increased. An oxidizing agent can be used individually by 1 type or in combination of 2 or more types.

Examples of the oxidizing agent include oxopiperidinium salt compounds such as 4-acetamido-2,2,6,6-tetramethyl-1-oxopiperidinium trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium trifluoride, onium salt compounds such as romethanesulfonate;

When the composition contains an oxidizing agent, the upper limit of the content of the oxidizing agent is preferably 30 parts by mass, more preferably 10 parts by mass, per 100 parts by mass of the [A] compound. As a minimum of the said content, 1 mass part is preferable and 3 mass parts is more preferable.

[Crosslinking agent]
The cross-linking agent is a component that forms cross-linked bonds between components such as the [A] compound in the composition or itself forms a cross-linked structure by the action of heat or acid. When the composition contains a cross-linking agent, the hardness of the formed resist underlayer film can be increased. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

Examples of cross-linking agents include polyfunctional (meth)acrylate compounds, epoxy compounds, hydroxymethyl group-substituted phenol compounds, alkoxyalkyl group-containing phenol compounds, and compounds having an alkoxyalkylated amino group.

When the composition contains a cross-linking agent, the upper limit of the content of the cross-linking agent is preferably 100 parts by mass, more preferably 50 parts by mass, relative to 100 parts by mass of the [A] compound. As a minimum of the said content, 5 mass parts is preferable and 10 mass parts is more preferable.

[Method for preparing composition]
The composition is prepared by mixing the [A] compound, [B] solvent, and optionally optional ingredients in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter of 0.1 μm or less. can be prepared by The lower limit of the concentration of the composition is preferably 0.1% by mass, more preferably 1% by mass, still more preferably 3% by mass, and particularly preferably 5% by mass. The upper limit of the concentration is preferably 50% by mass, more preferably 30% by mass, still more preferably 20% by mass, and particularly preferably 15% by mass.

<Resist underlayer film>
The resist underlayer film is formed from the composition. Since the resist underlayer film is formed from the above composition, it is excellent in heat resistance, film defect suppressing property, and etching resistance.

<Method for Forming Resist Underlayer Film>
The method for forming the resist underlayer film includes a step of directly or indirectly coating the composition on a substrate (hereinafter also referred to as a “coating step”), and usually forming a coating film formed by the coating step. and a step of heating (hereinafter also referred to as a “heating step”).

According to the method for forming the resist underlayer film, since the above-described composition is used, the resist underlayer film having excellent heat resistance, film defect suppressing property, and etching resistance can be formed. Each step will be described below.

[Coating process]
In this step, the composition is directly or indirectly applied to the substrate.

Examples of substrates include silicon wafers and aluminum-coated wafers. Moreover, the coating method of the composition is not particularly limited, and can be carried out by an appropriate method such as spin coating, casting coating, roll coating, and the like.

[Heating process]
This step is an optional step of heating the coating film formed by the coating step.

The coating film is usually heated in the air, but may be heated in a nitrogen atmosphere. As a minimum of the heating temperature of the said coating film, 100 degreeC is preferable and 200 degreeC is preferable. As an upper limit of the heating temperature of the said coating film, 600 degreeC is preferable and 500 degreeC is preferable. The lower limit of the heating time of the coating film is preferably 15 seconds, more preferably 30 seconds. The upper limit of the heating time for the coating film is preferably 600 seconds, more preferably 300 seconds.

Before heating the coating film at a temperature of 200° C. or higher and 600° C. or lower, it may be preheated at a temperature of 60° C. or higher and 150° C. or lower. The lower limit of the heating time in preheating is preferably 10 seconds, more preferably 30 seconds. The upper limit of the heating time is preferably 300 seconds, more preferably 180 seconds.

The lower limit of the average thickness of the resist underlayer film to be formed is preferably 30 nm, more preferably 50 nm, and even more preferably 100 nm. The upper limit of the average thickness is preferably 3,000 nm, more preferably 2,000 nm, and even more preferably 500 nm.

<Pattern formation method>
The pattern forming method includes a step of directly or indirectly coating the composition on a substrate (coating step), and a step of directly or indirectly forming a resist pattern on the resist underlayer film formed by the coating step. (hereinafter also referred to as “resist pattern forming step”), and a step of performing etching using the resist pattern as a mask (hereinafter also referred to as “etching step”).

According to the pattern forming method, since the above-described resist underlayer film having excellent heat resistance, etching resistance, and film defect suppressing property is used, a patterned substrate having a favorable pattern shape can be obtained.

The pattern forming method may optionally include a step of forming a silicon-containing film directly or indirectly on the resist underlayer film (hereinafter also referred to as a "silicon-containing film forming step"). Each step will be described below.

[Coating process]
In this step, the composition is directly or indirectly applied to the substrate. The pattern forming method usually includes a step of heating the coating film formed by the coating step (hereinafter also referred to as a "heating step"). Thereby, a resist underlayer film is formed. This step is the same as the coating step in the method for forming the resist underlayer film described above.

[Heating process]
In this step, the coating film formed by the coating step may be heated. This step is the same as the heating step in the method for forming the resist underlayer film described above.

[Silicon-containing film forming step]
In this step, a silicon-containing film is formed directly or indirectly on the resist underlayer film formed in the coating step.

A silicon-containing film can be formed by coating a composition for forming a silicon-containing film, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. As a method of forming a silicon-containing film by coating a composition for forming a silicon-containing film, for example, a coating film formed by directly or indirectly coating the composition for forming a silicon-containing film on the resist underlayer film. is cured by exposure and/or heating. Commercially available products of the silicon-containing film-forming composition include, for example, "NFC SOG01", "NFC SOG04", and "NFC SOG080" (manufactured by JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxynitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) and atomic layer deposition (ALD).

Radiation used for the exposure includes, for example, visible light, ultraviolet rays, far ultraviolet rays, electromagnetic waves such as X-rays and γ-rays, and particle beams such as electron beams, molecular beams and ion beams.

The lower limit of the temperature for heating the coating film is preferably 90°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the temperature is preferably 550°C, more preferably 450°C, and even more preferably 300°C. The lower limit of the time for heating the coating film is preferably 10 seconds, more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the silicon-containing film to be formed is preferably 1 nm, more preferably 10 nm, and even more preferably 20 nm. The upper limit of the average thickness is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm.

[Resist pattern forming step]
In this step, a resist pattern is formed directly or indirectly on the resist underlayer film. Examples of a method for performing this step include a method using a resist composition.

Specifically, in the method using the resist composition, after coating the resist composition so that the resulting resist film has a predetermined thickness, the solvent in the coated film is volatilized by pre-baking. , to form a resist film.

Examples of the resist composition include a positive-type or negative-type chemically amplified resist composition containing a radiation-sensitive acid generator, a positive-type resist composition containing an alkali-soluble resin and a quinonediazide-based photosensitizer, an alkali-soluble Examples include negative resist compositions containing a resin and a cross-linking agent.

The lower limit of the concentration of the resist composition is preferably 0.3% by mass, more preferably 1% by mass. The upper limit of the concentration is preferably 50% by mass, more preferably 30% by mass. In addition, the resist composition is generally filtered through a filter having a pore size of 0.2 μm or less, for example, to form a resist film. In addition, in this step, a commercially available resist composition can be used as it is.

The method of coating the resist composition is not particularly limited, and examples thereof include spin coating. The temperature for prebaking is appropriately adjusted according to the type of resist composition used, etc., but the lower limit of the above temperature is preferably 30°C, more preferably 50°C. The upper limit of the temperature is preferably 200°C, more preferably 150°C. The lower limit of the prebaking time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds.

Next, the resist film thus formed is exposed by selective radiation irradiation. Depending on the type of radiation-sensitive acid generator used in the resist composition, the radiation used for exposure includes electromagnetic waves such as visible light, ultraviolet rays, deep ultraviolet rays, X-rays and gamma rays, electron beams, molecular beams, It is appropriately selected from particle beams such as ion beams. Among these, far ultraviolet rays are preferred, and KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), _F2 excimer laser light (wavelength 157 nm), _Kr2 excimer laser light (wavelength 147 nm), ArKr excimer laser light. (wavelength 134 nm) or extreme ultraviolet rays (wavelength 13.5 nm, etc., EUV) are more preferred, and KrF excimer laser light, ArF excimer laser light, or EUV is even more preferred.

After the exposure, post-baking can be performed to improve the resolution, pattern profile, developability, and the like. The post-baking temperature is appropriately adjusted according to the type of resist composition used, etc., but the lower limit of the above temperature is preferably 50°C, more preferably 70°C. The upper limit of the temperature is preferably 200°C, more preferably 150°C. The lower limit of post-baking time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds.

Next, the exposed resist film is developed with a developer to form a resist pattern. This development may be either alkali development or organic solvent development. Examples of the developer for alkaline development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl Diethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5 -diazabicyclo[4.3.0]-5-nonene and other basic aqueous solutions. Suitable amounts of water-soluble organic solvents such as alcohols such as methanol and ethanol, surfactants and the like can also be added to these basic aqueous solutions. In the case of organic solvent development, the developer includes, for example, various organic solvents exemplified as the [B] solvent of the composition described above.

After developing with the developer, the resist is washed and dried to form a predetermined resist pattern.

As a method for performing the resist pattern forming step, in addition to the method using the resist composition described above, a method using a nanoimprint method, a method using a self-assembled composition, and the like can also be used.

[Etching process]
In this step, etching is performed using the resist pattern as a mask. Etching may be performed once or multiple times, that is, etching may be performed sequentially using the pattern obtained by etching as a mask, but multiple times is preferable from the viewpoint of obtaining a pattern with a better shape. When etching is performed multiple times, etching is performed sequentially in the order of the silicon-containing film, the underlying film, and the substrate. Etching methods include dry etching, wet etching, and the like. Among these, dry etching is preferable from the viewpoint of improving the pattern shape of the substrate. For this dry etching, gas plasma such as oxygen plasma is used. After the etching, a patterned substrate with a predetermined pattern is obtained.

Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the mask pattern, the elemental composition of the film to be etched, _{etc. For} example, _CHF3 , _CF4 , _C2F6 , _C3F8 , _SF6. chlorine-based gases such _as Cl ₂ and BCl ₃ ; oxygen _{- based} gases such as O _{2 , O 3} and H ₂ O _; , _C2H4 , _C2H6 , _C3H4 , _C3H6 , _{C3H8 ,} HF _, HI, HBr, _HCl , _NO , _{NH3 ,} reducing gases such as _BCl3 , He, N ₂ , an inert gas such as Ar is used. These gases can also be mixed and used. When etching a substrate using the pattern of the resist underlayer film as a mask, a fluorine-based gas is usually used. For example, since the mask pattern of the resist underlayer film is used in the step of forming via holes in the silicon oxide film (interlayer insulating film) on the substrate by fluorine gas etching, it is required to have excellent fluorine gas etching resistance.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Methods for measuring various physical properties are shown below.

[Average thickness of resist underlayer film]
The average thickness of the resist underlayer film was measured using a spectroscopic ellipsometer ("M2000D" manufactured by JA WOOLLAM).

<Synthesis of [A] compound>
[A] Compounds (A-1) to (A-5) were synthesized by the following method.

[Synthesis Example 1-1]
A three-necked flask equipped with a thermometer, a condenser and a magnetic stirrer was charged with 20.0 g of 1-pyrenecarbaldehyde and 259.3 g of N,N-diethylaniline under a nitrogen atmosphere and dissolved at room temperature. 0.4 g of 96% by mass sulfuric acid was added dropwise over 30 minutes. After completion of dropping, the mixture was heated to 60° C. and reacted for 10 hours. After completion of the reaction, this reaction solution was added to a large amount of water, and then 60 g of methyl isobutyl ketone (MIBK) and 30 g of tetrahydrofuran (THF) were added for extraction. After washing with water three times, the organic phase was poured into 600 g of hexane and reprecipitated. The obtained precipitate was dried overnight at 60° C. under reduced pressure to obtain the following compound (A-1) (molecular weight: 511).

[Synthesis Example 1-2]
3.93 g of N,N'-di-p-tolyl-3,3'-dimethylbenzidine and 4.73 g of 4-ethyliodobenzene were placed in a three-necked flask equipped with a thermometer, condenser and magnetic stirrer under an argon atmosphere. , 0.1 g of copper powder, 1.38 g of potassium carbonate and 20 mL of nitrobenzene were added, stirred with argon bubbling, and refluxed for 24 hours while removing water azeotropically with nitrobenzene. After filtering the reaction solution, nitrobenzene was distilled off and the residue was purified by alumina column chromatography to obtain the following compound (A-2) (molecular weight: 601).

[Synthesis Example 1-3]
20.0 g of 2-acetylfluorene and 20.0 g of m-xylene were placed in a reactor under a nitrogen atmosphere and dissolved at 110.degree. Then, 3.14 g of dodecylbenzenesulfonic acid was added, heated to 140° C. and reacted for 16 hours. After completion of the reaction, the reaction solution was diluted with 80 g of xylene, cooled to 50° C., and poured into 500 g of methanol for reprecipitation. After the obtained precipitate was washed with toluene, the solid was collected with filter paper and dried to obtain a compound (b-1) represented by the following formula (b-1).

10.0 g of the above compound (b-1), 8.23 g of N,N-dimethylaminobenzaldehyde and 50 g of toluene were added to a reaction vessel under a nitrogen atmosphere, and after stirring, 25.2 g of a 50% by mass aqueous sodium hydroxide solution and 1.7 g of tetrabutylammonium bromide was added and reacted at 92° C. for 12 hours. After cooling the reaction solution to 50° C., 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous oxalic acid solution was added to separate and extract the liquids, and then the mixture was added to hexane for reprecipitation. The resulting precipitate was collected with filter paper and dried to obtain the following compound (A-3) (molecular weight: 964).

[Synthesis Example 1-4]
5.00 g of 2,7-di-(N,N-diphenylamino)-9H-fluorene, 3.63 g of 1-bromohexane and 50 g of toluene were added to a reaction vessel under a nitrogen atmosphere, and after stirring, 50 mass % sodium hydroxide aqueous solution and 1.7 g of tetrabutylammonium bromide were added and reacted at 92° C. for 12 hours. After cooling the reaction solution to 50° C., 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous oxalic acid solution was added to separate and extract the liquids, and the mixture was poured into hexane for reprecipitation. The resulting precipitate was collected with filter paper and dried to obtain the following compound (A-4) (molecular weight: 669).

[Synthesis Example 1-5]
10 g of 5,11,17,23-tetra-t-butyl-25,26,27,28-tetramethoxy-2,8,14,20-tetraazacalix[4]arene was placed in a reaction vessel under a nitrogen atmosphere. , 20 g of butyl iodide, 11.5 g of 2,6-t-butyl-4-methylpyridine and 100 g of N,N-dimethylacetamide were charged and reacted at 40° C. for 48 hours. After cooling, it was washed with 60 g of cyclohexanone, 40 g of MIBK, and 5% by mass hydrochloric acid water, and MIBK was distilled off, and diluted with cyclohexanone to obtain a 10% by mass solution of the following compound (A-5) (molecular weight: 933).

[Synthesis Example 2-1]
A resin represented by the following formula (a-1) was synthesized by the following method. In a reaction vessel, 250.0 g of 4-cresol, 125.0 g of 37 mass% formalin and 2 g of anhydrous oxalic acid were added under a nitrogen atmosphere, reacted at 100°C for 3 hours and at 180°C for 1 hour, and then reduced under reduced pressure. Unreacted monomers were removed to obtain a resin represented by the following formula (a-1).

<Preparation of Composition for Forming Resist Underlayer Film>
The [A] compound, [B] solvent, [C] oxidizing agent and [D] cross-linking agent used in the preparation of the composition for forming a resist underlayer film are shown below.

[[A] compound]
Examples: Compounds (A-1) to (A-5) synthesized above
Comparative example: Resin (a-1) synthesized above

[[B] solvent]
B-1: propylene glycol monomethyl ether acetate B-2: cyclohexanone

[[C] oxidizing agent]
C-1: 4-acetamido-2,2,6,6-tetramethyl-1-oxopiperidinium trifluoromethanesulfonate (compound represented by the following formula (C-1))
C-2: bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate (compound represented by the following formula (C-2))

[[D] cross-linking agent]
D-1: 1,3,4,6-tetrakis(methoxymethyl)glycoluril (compound represented by the following formula (D-1))

[Example 1-1]
[A] 10 parts by mass of (A-1) as a compound was dissolved in 90 parts by mass of (B-1) as a [B] solvent. The resulting solution was filtered through a membrane filter with a pore size of 0.1 μm to prepare a resist underlayer film-forming composition (J-1).

[Examples 1-2 to 1-10 and Comparative Example 1-1]
Compositions (J-2) to (J-10) and (CJ) for forming a resist underlayer film were prepared in the same manner as in Example 1-1, except that each component having the type and content shown in Table 1 below was used. -1) was prepared. "-" in Table 1 indicates that the corresponding component was not used.

<Formation of resist underlayer film>
[Examples 2-1 to 2-10 and Comparative Example 2-1]
The composition for forming a resist underlayer film prepared above was coated on a silicon wafer (substrate) by a spin coating method using a spin coater (“CLEAN TRACK ACT 12” available from Tokyo Electron Ltd.). Next, in an air atmosphere, after heating (baking) at the heating temperature (° C.) and heating time (sec) shown in Table 2 below, the resist underlayer film having an average thickness of 200 nm was obtained by cooling at 23° C. for 60 seconds. was formed to obtain a substrate with a resist underlayer film in which a resist underlayer film was formed on the substrate.

<Evaluation>
Using the composition for forming a resist underlayer film and the substrate with a resist underlayer film obtained above, the following items were evaluated by the following methods. The evaluation results are also shown in Table 2 below.

[Heat-resistant]
The composition for forming a resist underlayer film prepared above is applied to a silicon wafer having a diameter of 8 inches by a spin coating method, and baked at 250° C. for 60 seconds in an air atmosphere to form a resist underlayer film. Then, a substrate with a resist underlayer film was obtained. Next, the powder is collected by scraping the resist underlayer film of the substrate with the resist underlayer film, and the powder of the resist underlayer film is a container used for measurement with a TG-DTA device (“TG-DTA2000SR” by NETZSCH). was placed in a container and the mass before heating was measured. Next, using the above TG-DTA apparatus, the powder was heated to 400° C. at a heating rate of 10° C./min in a nitrogen atmosphere, and the mass of the powder at 400° C. was measured. Then, the mass reduction rate (%) was measured by the following formula, and this mass reduction rate was used as a measure of heat resistance.
M _L = {(m1−m2)/m1}×100
Here, in the above formula, _ML is the mass reduction rate (%), m1 is the mass before heating (mg), and m2 is the mass at 400°C (mg).
As for the heat resistance, the smaller the mass reduction rate of the powder used as the sample, the less the sublimate generated during heating of the resist underlayer film and the decomposition product of the resist underlayer film. That is, the smaller the mass reduction rate, the higher the heat resistance. The heat resistance is "A" (very good) when the mass reduction rate is less than 5%, "B" (good) when it is 5% or more and less than 10%, and "C" when it is 10% or more ( bad).

[Etching resistance]
The resist underlayer film on the substrate with the resist underlayer film thus obtained was etched using an etching apparatus ("TACTRAS" manufactured by Tokyo Electron Ltd.) with CF ₄ /Ar=110/440 sccm, PRESS. = 30 MT, HF RF (radio frequency power for plasma generation) = 500 W, LF RF (radio frequency power for bias) = 3000 W, DCS = -150 V, RDC (gas center flow ratio) = 50%, 30 sec. The etching rate (nm/min) was calculated from the average thicknesses of the resist underlayer films before and after. Next, the ratio to Comparative Example 2-1 was calculated based on the etching rate of Comparative Example 2-1, and used as a measure of etching resistance. The etching resistance was evaluated as "A" (good) when the ratio was 0.98 or more and less than 1.00, and as "B" (bad) when the ratio was 1.00 or more. "-" in the column of etching resistance in Table 2 indicates the evaluation criteria.

[Film Defect Suppression]
A composition for forming a silicon-containing film (“NFC SOG080” available from JSR Corporation) was applied onto the substrate with the resist underlayer film obtained above by a spin coating method, and then coated at 200° C. for 60 seconds in an air atmosphere. A silicon-containing film having an average thickness of 50 nm was formed by heating (baking) to obtain a silicon-containing film-coated substrate. After further heating (baking) the substrate with the silicon-containing film obtained above at 450° C. for 60 seconds, the surface of the silicon-containing film was observed with an optical microscope. The film defect suppression property was evaluated as "A" (good) when no cracking or peeling of the silicon-containing film was observed, and as "B" (poor) when cracking or peeling of the silicon-containing film was observed. .

As can be seen from the results in Table 2, the resist underlayer films formed from the resist underlayer film-forming compositions of Examples are excellent in heat resistance, etching resistance, and film defect suppressing properties. On the other hand, the resist underlayer film formed from the composition for forming a resist underlayer film of Comparative Example had poor heat resistance and film defect suppressing properties, and was inferior in etching resistance.

[Resist pattern formation]
A composition for forming a silicon-containing film (JSR Corporation's " NFC SOG080") was applied by a spin coating method, and then heated (baked) at 200° C. for 60 seconds in an air atmosphere to form a silicon-containing film having an average thickness of 50 nm, thereby obtaining a substrate with a silicon-containing film. Next, an ArF resist composition (“AR1682J” available from JSR Corporation) is applied onto the silicon-containing film by a spin coating method, and heated (baked) at 130° C. for 60 seconds in an air atmosphere. , a resist film having an average thickness of 200 nm was formed. Thereafter, the resist film is exposed through a 1:1 line-and-space mask pattern with a target size of 100 nm using an ArF excimer laser exposure apparatus (lens numerical aperture: 0.78, exposure wavelength: 193 nm) manufactured by Nikon Corporation. , After exposure by changing the exposure amount, heating (baking) at 130 ° C. for 60 seconds in an air atmosphere, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, at 25 ° C. for 1 minute. Developed, washed with water and dried. By observing the resist film with a scanning electron microscope ("CG-4000" by Hitachi High-Technologies Corporation), a line-and-space resist pattern with a line pattern of 200 nm pitch and a line width of 30 nm to 100 nm. was confirmed to be formed.

The composition for forming a resist underlayer film of the present invention can form a resist underlayer film that is excellent in heat resistance, etching resistance, and film defect suppressing properties. The resist underlayer film of the present invention is excellent in heat resistance, etching resistance and film defect suppressing property. According to the method for forming a resist underlayer film of the present invention, a resist underlayer film having excellent heat resistance, etching resistance, and film defect suppressing properties can be formed. According to the pattern forming method of the present invention, a patterned substrate having a favorable pattern shape can be obtained by using such an excellent resist underlayer film. Therefore, these can be suitably used for the manufacture of semiconductor devices, etc., which are expected to be further miniaturized in the future.

Claims (11)

a compound having an aromatic ring and a nitrogen atom bonded to a carbon atom of the aromatic ring;
containing a solvent and
A composition for forming a resist underlayer film, wherein the compound is represented by the following formula (1) or (2).

(In formula (1), R ¹ is a group represented by the following formula (3) . R ³ and R ⁴ each independently represent a substituted or unsubstituted monovalent C 1-20 a hydrocarbon group or a hydrogen atom (with the proviso that at least one of R ³ and R ⁴ is an unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ³ and R ⁴ is a chain carbonized When it is a hydrogen group, the chain hydrocarbon group is an alkane with one hydrogen atom removed), or R ³ and R ⁴ are combined with each other and formed with the nitrogen atom to which they are attached. It is part of a ring structure having 3 to 20 ring members, provided that at least one of R ¹ , R ³ and R ⁴ has an aromatic ring, and the carbon atom of this aromatic ring is A group bonded to a nitrogen atom, n is an integer of 2 to 10. Plural R ³ are the same or different, and plural R ⁴ are the same or different.
In formula (2), R ^2′ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. R ^3′ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom. However, at least one of R ^2' and R ^3' is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (2) through a carbon atom of the aromatic ring. m is an integer from 1 to 10; When m is 2 or more, multiple R ^2' are the same or different, and multiple R ^3' are the same or different. )

(In the formula (3), Ar ¹ is a group obtained by removing (p+a) hydrogen atoms on an aromatic ring from an arene having 6 to 70 carbon ^atoms . is an organic group, a hydroxy group, or a halogen atom, p is an integer of 0 to 20. When p is 2 or more, multiple R ^A are the same or different, and a is an integer of 1 to 10.* indicates the bonding site with the nitrogen atom in the above formula (1).) R ³ and R ⁴ in the above formula (1) are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, or R ³ and R ⁴ are combined with each other and the nitrogen atom to which they are bonded 2. The composition for forming a resist underlayer film according to claim 1 , which is a part of a ring structure having 3 to 20 ring members formed together with 3. The composition for forming a resist underlayer film according to claim 1, wherein the group represented by formula (3) is any one of the groups represented by the following formulae.

(In the above formula, each R is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. * has the same meaning as in formula (3) above.) 4. The composition for forming a resist underlayer film according to any one of claims 1 to 3 , wherein the compound has a molecular weight of 4,000 or less. 5. The composition for forming a resist underlayer film according to any one of claims 1 to 4 , wherein the content of the compound is 50% by mass or more with respect to all components other than the solvent. A resist underlayer film formed from the composition for forming a resist underlayer film according to claim 1 . A step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate,
The composition for forming a resist underlayer film is
a compound having an aromatic ring and a nitrogen atom attached to a carbon atom of the aromatic ring; and a solvent,
A method for forming a resist underlayer film in which the compound is represented by the following formula (1) or (2).

(In formula (1), R ¹ is a group represented by the following formula (3) . R ³ and R ⁴ each independently represent a substituted or unsubstituted monovalent C 1-20 a hydrocarbon group or a hydrogen atom (with the proviso that at least one of R ³ and R ⁴ is an unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ³ and R ⁴ is a chain carbonized When it is a hydrogen group, the chain hydrocarbon group is an alkane with one hydrogen atom removed), or R ³ and R ⁴ are combined with each other and formed with the nitrogen atom to which they are attached. It is part of a ring structure having 3 to 20 ring members, provided that at least one of R ¹ , R ³ and R ⁴ has an aromatic ring, and the carbon atom of this aromatic ring is A group bonded to a nitrogen atom, n is an integer of 2 to 10. Plural R ³ are the same or different, and plural R ⁴ are the same or different.
In formula (2), R ^2′ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. R ^3′ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom. However, at least one of R ^2' and R ^3' is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (2) through a carbon atom of the aromatic ring. m is an integer from 1 to 10; When m is 2 or more, multiple R ^2' are the same or different, and multiple R ^3' are the same or different. )

(In the formula (3), Ar ¹ is a group obtained by removing (p+a) hydrogen atoms on an aromatic ring from an arene having 6 to 70 carbon ^atoms . is an organic group, a hydroxy group, or a halogen atom, p is an integer of 0 to 20. When p is 2 or more, multiple R ^A are the same or different, and a is an integer of 1 to 10.* indicates the bonding site with the nitrogen atom in the above formula (1).) 8. The method of forming a resist underlayer film according to claim 1, wherein the group represented by formula (3) is any one of the groups represented by the following formulae.

(In the above formula, each R is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. * has the same meaning as in formula (3) above.) a step of directly or indirectly applying a composition for forming a resist underlayer film onto a substrate;
a step of directly or indirectly forming a resist pattern on the resist underlayer film formed by the coating step;
and a step of performing etching using the resist pattern as a mask,
The composition for forming a resist underlayer film is
a compound having an aromatic ring and a nitrogen atom attached to a carbon atom of the aromatic ring; and a solvent,
A pattern forming method wherein the compound is represented by the following formula (1) or (2).

(In formula (1), R ¹ is a group represented by the following formula (3) . R ³ and R ⁴ each independently represent a substituted or unsubstituted monovalent C 1-20 a hydrocarbon group or a hydrogen atom (with the proviso that at least one of R ³ and R ⁴ is an unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ³ and R ⁴ is a chain carbonized When it is a hydrogen group, the chain hydrocarbon group is an alkane with one hydrogen atom removed), or R ³ and R ⁴ are combined with each other and formed with the nitrogen atom to which they are attached. It is part of a ring structure having 3 to 20 ring members, provided that at least one of R ¹ , R ³ and R ⁴ has an aromatic ring, and the carbon atom of this aromatic ring is A group bonded to a nitrogen atom, n is an integer of 2 to 10. Plural R ³ are the same or different, and plural R ⁴ are the same or different.
In formula (2), R ^2′ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. R ^3′ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom. However, at least one of R ^2' and R ^3' is a group having an aromatic ring and bonding to the nitrogen atom in the above formula (2) through a carbon atom of the aromatic ring. m is an integer from 1 to 10; When m is 2 or more, multiple R ^2' are the same or different, and multiple R ^3' are the same or different. )

(In the formula (3), Ar ¹ is a group obtained by removing (p+a) hydrogen atoms on an aromatic ring from an arene having 6 to 70 carbon ^atoms . is an organic group, a hydroxy group, or a halogen atom, p is an integer of 0 to 20. When p is 2 or more, multiple R ^A are the same or different, and a is an integer of 1 to 10.* indicates the bonding site with the nitrogen atom in the above formula (1).) Before the process of forming a resist pattern,
10. The pattern forming method according to claim 9 , comprising a step of directly or indirectly forming a silicon-containing film on the resist underlayer film formed by the coating step. 11. The pattern forming method according to claim 1, wherein the group represented by formula (3) is any one of the groups represented by the following formulae.

(In the above formula, each R is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. * has the same meaning as in formula (3) above.)