Composition for forming resist underlayer film, method for producing semiconductor substrate, and polymer

Abstract

The present invention provides: a composition for forming a resist underlayer film with which a resist underlayer film having excellent resist pattern rectangularity can be formed; a method for producing a semiconductor substrate; and a polymer. This composition for forming a resist underlayer film contains a polymer having a group that generates radicals upon irradiation with radiation, and a solvent. The polymer preferably has at least one group that generates radicals upon irradiation with radiation, the group being selected from the group consisting of formulae (A1) to (A8).

Description

Composition for forming resist underlayer film, method for manufacturing semiconductor substrate, and polymer

[0001] The present invention relates to a composition for forming a resist underlayer film, a method for producing a semiconductor substrate, and a polymer.

[0002] 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 via a resist underlayer film such as an organic underlayer film or a silicon-containing film. In this process, the resist underlayer film is etched using the resist pattern as a mask, and the substrate is further etched using the resulting resist underlayer film pattern as a mask, thereby forming a desired pattern on the semiconductor substrate.

[0003] In recent years, semiconductor devices have become increasingly highly integrated, and the wavelength of the exposure light used has tended to be shortened from KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) to extreme ultraviolet light (13.5 nm, hereinafter also referred to as "EUV"). Various studies have been conducted on compositions for forming resist underlayer films (see International Publication No. 2013 / 141015).

[0004] International Publication No. 2013 / 141015

[0005] The resist underlayer film is required to have a resist pattern rectangularity that suppresses pattern footing at the bottom of the resist film and ensures the rectangularity of the resist pattern.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a composition for forming a resist underlayer film, a method for producing a semiconductor substrate, and a polymer that are capable of forming a resist underlayer film that exhibits excellent resist pattern rectangularity.

[0007] In one embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a polymer having a group that generates a radical upon irradiation with radiation (hereinafter also referred to as “polymer [A]”); and a solvent (hereinafter also referred to as “solvent [B]”).

[0008] In another embodiment, the present invention relates to a method for producing a semiconductor substrate, comprising: a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate; a step of forming a resist film on the resist underlayer film formed by the step of applying the composition for forming a resist underlayer film; a step of exposing the resist film to radiation; and a step of developing at least the exposed resist film, wherein the composition for forming a resist underlayer film contains a polymer having a group that generates a radical upon irradiation with radiation, and a solvent.

[0009] In still another embodiment, the present invention relates to a polymer having at least one group capable of generating a radical upon irradiation with radiation, selected from the group consisting of the following formulae (A1) to (A8): (In the above formulas (A-1) to (A-8), R １ ~R １０ and R １２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. １１ is a monovalent organic group having 1 to 20 carbon atoms. ａ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, and R ｂ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｃ R is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｄ and R ｅ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, or R ｄ and R ｅ are combined with each other to form a divalent alicyclic group having 3 to 10 carbon atoms together with the carbon atoms to which they are attached. １ are each independently a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. ｆ is a monovalent organic group having 1 to 20 carbon atoms. ｇis a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. ｇ In the formula (A7), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. ｈ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ｈ In the formula (A8), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. * indicates a bond to another part of the polymer.

[0010] The composition for forming a resist underlayer film can form a film with excellent resist pattern rectangularity. The method for producing a semiconductor substrate uses a composition for forming a resist underlayer film capable of forming a resist underlayer film with excellent resist pattern rectangularity, allowing for efficient production of semiconductor substrates. The polymer can be suitably used as a component of the composition for forming a resist underlayer film. Therefore, these can be suitably used in the production of semiconductor devices, etc.

[0011] The composition for forming a resist underlayer film, the method for producing a semiconductor substrate, and the polymer according to each embodiment of the present invention will be described in detail below. Combinations of preferred aspects in the embodiments are also preferred.

[0012] <<Composition for forming a resist underlayer film>> The composition for forming a resist underlayer film (hereinafter also referred to as the “composition”) contains a polymer (A) and a solvent (B). The composition may contain optional components as long as the effects of the present invention are not impaired.

[0013] The composition is suitable as a composition for forming an underlayer film of a resist film to be exposed to extreme ultraviolet rays. Examples of resist film-forming compositions include positive- or negative-type chemically amplified resist compositions containing a radiation-sensitive acid generator, positive-type resist compositions containing an alkali-soluble resin and a quinone diazide photosensitizer, negative-type resist compositions containing an alkali-soluble resin and a crosslinker, and metal-containing resist compositions containing metals such as tin, zirconium, and hafnium. The underlayer film formed from the composition contains groups derived from the polymer (A) that generate radicals upon irradiation with radiation. As a result, radicals are generated upon exposure to extreme ultraviolet rays or the like, which creates a sufficient difference in solubility in the interfacial region of the organic resist film on the underlayer film side and promotes insolubilization of the metal-containing resist film, thereby suppressing pattern footing at the bottom of the resist film and ensuring rectangularity of the resist pattern. The lower limit of the content of the metal or metal compound in the components other than the solvent in the metal-containing resist composition is preferably 50 mass %, more preferably 70 mass %, even more preferably 80 mass %, and particularly preferably 85 mass %. The upper limit of the content is, for example, 100 mass % or 95 mass %.

[0014] Each component contained in the composition will be described below.

[0015] <Polymer [A]> The polymer [A] has a group (hereinafter also referred to as "group (X)") that generates a radical upon irradiation with radiation. The polymer [A] can have one or more types of group (X). The composition can contain one or more types of polymer [A]. The form of the polymer [A] is not particularly limited, and may be any polymerization reactant such as an addition polymerization reactant, a polycondensation reactant, a polyaddition reactant, or an addition-condensation reactant.

[0016] Regardless of the form of the polymer [A], it is preferable that the polymer [A] has at least one group capable of generating a radical upon irradiation with radiation selected from the group consisting of the following formulae (A1) to (A8): (In the above formulas (A1) to (A8), R １ ~R １０ and R １２are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. １１ is a monovalent organic group having 1 to 20 carbon atoms. ａ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, and R ｂ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｃ R is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｄ and R ｅ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, or R ｄ and R ｅ are combined with each other to form a divalent alicyclic group having 3 to 10 carbon atoms together with the carbon atoms to which they are attached. １ are each independently a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. ｆ is a monovalent organic group having 1 to 20 carbon atoms. ｇ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. ｇ In the formula (A7), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. ｈ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ｈ In the formula (A8), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. * indicates a bond to another part of the polymer.

[0017] In the above formulas (A1) to (A2), R １ ~R １０ and R １２ As the monovalent organic group having 1 to 10 carbon atoms represented by R １１ Among the monovalent organic groups having 1 to 20 carbon atoms represented by the formula (I), groups having 1 to 10 carbon atoms can be suitably used. １１The monovalent organic group having 1 to 20 carbon atoms represented by the following formula will be explained first.

[0018] In the above formula (A1), R １１ Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (a) having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the terminal of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group or the group (a) have been substituted with a monovalent heteroatom-containing substituent, or a combination thereof.

[0019] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and combinations thereof.

[0020] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0021] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group; cycloalkenyl groups such as a cyclopropenyl group, a cyclopentenyl group and a cyclohexenyl group; bridged ring saturated hydrocarbon groups such as a norbornyl group, an adamantyl group and a tricyclodecyl group; and bridged ring unsaturated hydrocarbon groups such as a norbornenyl group and a tricyclodecenyl group.

[0022] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, anthracenyl, and pyrenyl; and aralkyl groups such as benzyl and phenethyl.

[0023] Examples of heteroatoms constituting the divalent heteroatom-containing linking group or monovalent heteroatom-containing substituent include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, halogen atoms, etc. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0024] Examples of the divalent heteroatom-containing linking group include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ - or a group combining these, etc. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0025] Examples of the monovalent heteroatom-containing substituent include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0026] In the above formula (A1), R １１ is preferably a chain hydrocarbon group having 1 to 6 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms or a substituted or unsubstituted phenyl group, and even more preferably a methyl group, an ethyl group, an n-propyl group, or a substituted or unsubstituted phenyl group. As the substituent for the phenyl group, a halogen atom, a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 6 carbon atoms, or a combination of these groups with -O- is preferred, and a fluorine atom, an iodine atom, or a glycidyloxy group is more preferred.

[0027] As mentioned above, R １ ~R １０ and R １２ As the monovalent organic group having 1 to 10 carbon atoms represented by R １１ Among the monovalent organic groups having 1 to 20 carbon atoms represented by the following formula, groups having 1 to 10 carbon atoms can be suitably used.

[0028] In the above formulas (A1) to (A2), R １ ~R ４ are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms, further preferably a hydrogen atom, a methyl group or an ethyl group, and particularly preferably a methyl group.

[0029] In the above formulas (A1) to (A2), R ５ ~R ８ are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms, still more preferably a hydrogen atom, a methyl group, or an ethyl group, and particularly preferably a hydrogen atom.

[0030] In the above formulas (A1) to (A2), R ９ ~R １０ are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms, still more preferably a hydrogen atom, a methyl group, or an ethyl group, and particularly preferably a hydrogen atom or a methyl group.

[0031] In the above formula (A2), R １２ is preferably a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 6 carbon atoms, or a combination of these groups with -O-, and more preferably a hydrogen atom or a glycidyloxy group.

[0032] In the above formula (A3), R ａ As the divalent hydrocarbon group having 1 to 20 carbon atoms in the formula (A1), R １１ A group in which one hydrogen atom has been removed from the above-mentioned monovalent hydrocarbon group having 1 to 20 carbon atoms can be suitably used.

[0033] R ａ When has a substituent, examples of the substituent include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, an alkoxycarbonyl group such as a methoxycarbonyl group or an ethoxycarbonyl group, an alkoxycarbonyloxy group such as a methoxycarbonyloxy group or an ethoxycarbonyloxy group, an acyl group such as a formyl group, an acetyl group, a propionyl group, a butyryl group, or a benzoyl group, an acyloxy group such as an acetoxy group or a benzoyloxy group, a hydroxy group, a cyano group, a nitro group, and an oxo group (═O).

[0034] Rａ As the divalent hydrocarbon group having 1 to 20 carbon atoms, an arenediyl group having 6 to 14 carbon atoms is preferred, an arenediyl group having 6 to 10 carbon atoms is more preferred, and a benzenediyl group is even more preferred.

[0035] In the above formula (A3), R ｂ The monovalent hydrocarbon group having 1 to 20 carbon atoms in the formula (A1) is R １１ The monovalent hydrocarbon group having 1 to 20 carbon atoms as described above can be suitably used.

[0036] R ｂ The monovalent hydrocarbon group having 1 to 20 carbon atoms in is preferably an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 14 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms, and even more preferably a methyl group or a phenyl group.

[0037] R ｂ When has a substituent, the substituent is R ａ The substituents that may be possessed by the group can be suitably employed.

[0038] R ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ａ As the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the formula (A1), R １１ In this case, a group in which one hydrogen atom has been removed from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms can be preferably used. ｂ The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the formula (A1) is R １１ Among these, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms represented by the formula R ａ is an arenediyl group having 6 to 14 carbon atoms, and R ｂ is preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R ａ is an arenediyl group having 6 to 10 carbon atoms, and R ｂis preferably an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R ａ is a benzenediyl group, and R ｂ More preferably, is a methyl group or a phenyl group.

[0039] In the above formula (A4), R ｃ The divalent aromatic hydrocarbon group having 6 to 20 carbon atoms in R ａ The divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms in the above formula can be preferably used. ｃ The divalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the formula (I) is preferably an arenediyl group having 6 to 14 carbon atoms, more preferably an arenediyl group having 6 to 10 carbon atoms, and even more preferably a benzenediyl group.

[0040] R ｃ When has a substituent, the substituent is R ａ The substituents that may be possessed by the group can be suitably employed.

[0041] R ｄ and R ｅ The monovalent organic group having 1 to 10 carbon atoms represented by the formula (A1) is R １ A monovalent organic group having 1 to 10 carbon atoms and represented by the following formula can be suitably used.

[0042] R ｄ and R ｅ Examples of the divalent alicyclic group having 3 to 10 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded include R １１ A group in which one hydrogen atom has been removed from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0043] R ｄ and R ｅare each preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms or form a cycloalkanediyl group having 3 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms or form a cycloalkanediyl group having 4 to 8 carbon atoms, and further preferably a methyl group, an ethyl group, or form a cyclopentanediyl group or a cyclohexanediyl group.

[0044] In the above formulas (A5) to (A8), Ar １ Examples of the aromatic ring having 3 to 20 carbon atoms in Ar include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, and a perylene ring, and heteroaromatic rings such as a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring, and combinations thereof. １ The aromatic ring is preferably a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring, and more preferably a benzene ring or a naphthalene ring.

[0045] In addition, Ar １ When the aromatic ring has a polycyclic structure, Ar １ The two bonds bonded to may both be bonded to one aromatic ring in the polycyclic structure, or one bond may be bonded to one aromatic ring in the polycyclic structure and the other bond may be bonded to another aromatic ring in the polycyclic structure.

[0046] In the above formula (A6), R ｆ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (A1) is R １１ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used. ｆ As the alkyl group, a monovalent hydrocarbon group having 1 to 10 carbon atoms is preferable, a monovalent chain hydrocarbon group having 1 to 8 carbon atoms is more preferable, an alkyl group having 1 to 6 carbon atoms is further preferable, and a methyl group or an ethyl group is particularly preferable.

[0047] In the above formula (A7), R ｇAs the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (A3), ａ A divalent hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0048] R ｇ When has a substituent, the substituent is R ａ The substituents that may be possessed by the group can be suitably employed.

[0049] R ｇ As the alkyl group, an alkanediyl group having 1 to 10 carbon atoms or a cyclohexanediyl group having 3 to 10 carbon atoms is preferred, since at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N in the above formula (A7), an alkanediyl group having 1 to 6 carbon atoms or a cyclohexanediyl group having 4 to 8 carbon atoms is more preferred, and an ethanediyl group, a propane-1,3-diyl group, a cyclopentanediyl group or a cyclohexanediyl group is even more preferred.

[0050] In the above formula (A8), R ｈ The monovalent hydrocarbon group having 1 to 20 carbon atoms in the formula (A3) is R ｂ A monovalent hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0051] R ｈ When R has a substituent, the substituent may be R ａ The substituents that may be possessed by the group can be suitably employed.

[0052] R ｈ As the alkyl group, a monovalent hydrocarbon group having 1 to 10 carbon atoms is preferable, a monovalent chain hydrocarbon group having 1 to 8 carbon atoms is more preferable, an alkyl group having 1 to 6 carbon atoms is further preferable, and a methyl group or an ethyl group is particularly preferable.

[0053] Specific examples of the group (X) represented by formula (A1) above include structures represented by formulas (A1-1) to (A1-9) below. In the formulas below, * represents a bond to another part of the polymer. The same applies to the formulas and radical generation schemes of specific examples of the group (X) represented by formulas (A2) to (A8) below.

[0054] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A1) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0055] Specific examples of the group (X) represented by the above formula (A2) include structures represented by the following formulae (A2-1) to (A2-6).

[0056] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A2) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0057] Specific examples of the group (X) represented by the above formula (A3) include structures represented by the following formulae (A3-1) to (A3-6).

[0058] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A3) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0059] Specific examples of the group (X) represented by the above formula (A4) include structures represented by the following formulae (A4-1) to (A4-6).

[0060] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A4) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0061] Specific examples of the group (X) represented by the above formula (A5) include structures represented by the following formulae (A5-1) to (A5-6).

[0062] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A5) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0063] Specific examples of the group (X) represented by the above formula (A6) include structures represented by the following formulae (A6-1) to (A6-6).

[0064] A typical specific embodiment of radical generation in the group (X) represented by the above formula (A6) is shown in the following scheme: In the following scheme, by-products produced after irradiation are omitted.

[0065] Specific examples of the group (X) represented by the above formula (A7) include structures represented by the following formulae (A7-1) to (A7-6).

[0066] The specific mode of radical generation in the group (X) represented by the above formula (A7) is exemplified by the following scheme: ｇ The following explanation will be given using an example where is an ethanediyl group. The same applies to other structures. In the following scheme, by-products produced after irradiation are omitted.

[0067] Specific examples of the group (X) represented by the above formula (A8) include structures represented by the following formulae (A8-1) to (A8-4).

[0068] The specific mode of radical generation in the group (X) represented by the above formula (A8) is exemplified by the following scheme: ｈ The following explanation will be given using the case where is a propyl group as an example. The same applies to other structures. In the following scheme, by-products produced after irradiation are omitted.

[0069] The polymer (A) is preferably an addition polymerization product obtained by a radical polymerization reaction, and more preferably an acrylic polymer.

[0070] The polymer (A) preferably has a repeating unit represented by the following formula (1) (hereinafter also referred to as “repeating unit (1)”). (In the above formula (1), R ０is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group with a valence of 1+n. X is a group that generates a radical upon irradiation with radiation. n is an integer of 1 to 5. When n is 2 or more, multiple Xs are the same or different.

[0071] R ０ The monovalent hydrocarbon group having 1 to 20 carbon atoms in the formula (A1) is R １１ The monovalent hydrocarbon group having 1 to 20 carbon atoms as described above can be suitably used.

[0072] R ０ When R has a substituent, the substituent may be R ａ The substituents that may be possessed by the group can be suitably employed.

[0073] R ０ is preferably a hydrogen atom or a methyl group.

[0074] L １ Examples of the (1+n)-valent linking group represented by the formula (1) include hydrocarbons, —COO—, —OCO—, —O—CO—O—, —CONH—, —O—, —S—, —CO—, and groups in which 1+n hydrogen atoms have been removed from a structure comprising a combination of these.

[0075] L １ The hydrocarbon in the above formula (A1) is R １１ Among these, structures corresponding to the monovalent hydrocarbon groups having 1 to 20 carbon atoms in the above formula can be preferably employed. １ The hydrocarbon in is preferably a chain hydrocarbon having 1 to 10 carbon atoms, an alicyclic hydrocarbon having 3 to 10 carbon atoms, or an aromatic hydrocarbon having 6 to 10 carbon atoms, and more preferably methane, ethane, propane, n-butane, isobutane, cyclopentane, cyclohexane, or benzene.

[0076] L １ Preferred examples of the alkyl group include methane, ethane, propane, n-butane, isobutane, cyclopentane, cyclohexane, benzene, —COO—, —OCO—, —CONH—, —O—, —CO—, and groups in which 1+n hydrogen atoms have been removed from these structures.

[0077] The group represented by the formula (1) that generates radicals upon irradiation with X-rays is preferably at least one group selected from the group consisting of the formulae (A1) to (A8) above.

[0078] n is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0079] Specific examples of monomers that provide the repeating unit (1) include compounds represented by the following formulae (aa1-1) to (aa1-11), (aa2-1) to (aa2-6), (aa3-1) to (aa3-8), (aa4-1) to (aa4-9), (aa5-1) to (aa5-12), (aa6-1) to (aa6-6), (aa7-1) to (aa7-8), and (aa8-1) to (aa8-4).

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] In the above formulae (aa1-1) to (aa1-11), (aa2-1) to (aa2-6), (aa3-1) to (aa3-8), (aa4-1) to (aa4-9), (aa5-1) to (aa5-12), (aa6-1) to (aa6-6), (aa7-1) to (aa7-8), and (aa8-1) to (aa8-4), R ０ is synonymous with the above formula (1).

[0092] The lower limit of the content of repeating unit (1) in all repeating units constituting the polymer (A) (the total content when multiple types are present) is preferably 1 mol%, more preferably 10 mol%, and even more preferably 20 mol%, and the upper limit of the content is preferably 60 mol%, more preferably 45 mol%, and even more preferably 35 mol%.

[0093] It is preferable that the polymer [A] further has a repeating unit represented by the following formula (2) (excluding the case of the above formula (1)) (hereinafter also referred to as "repeating unit (2)"). The polymer [A] may have one or more types of repeating unit (2). (In formula (2), R ３Ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３Ａ is a single bond or a divalent linking group. ４Ａ is a group selected from the group consisting of groups represented by any one of the following formulas (2-1) to (2-8): (In formulas (2-1) to (2-3), (2-7), R ８Ａ , R ９Ａ , R １０Ａ , R １２Ａ and R １３Ａ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (2-2), Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in the formula. R １１Ａ is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. ** is a bond to an atom constituting Cy. However, R １１Ａ is a single bond, R １１Ａ In formulas (2-1) to (2-8), R７Ａ is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３Ａ is the bond to the atoms that make up the atom.)

[0094] R ３Ａ As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (A1), R １１ The monovalent hydrocarbon groups having 1 to 20 carbon atoms shown in the following formula can be preferably used. ３Ａ When R has a substituent, the substituent is ａ Examples of the substituent include the groups listed above.

[0095] L ３Ａ The divalent linking group represented by the formula (1) is １ Among the groups listed as the (1+n)-valent linking group represented by the formula (I), groups in which n is 1 are exemplified. ３Ａ As the group, a single bond, -COO- ＊ ( ＊ is R ４Ａ is a bond to the group represented by the formula (I).) or a benzenediyl group is preferred.

[0096] In the above formulas (2-1) to (2-3) and (2-7), R ８Ａ ~R １３Ａ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (A1) is R １１ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0097] R ８Ａ ~R １３Ａ are each independently preferably a hydrogen atom or a methyl group, and more preferably all are a hydrogen atom.

[0098] In the formula (2-2), examples of the ring structure having 3 to 20 ring members formed together with the two carbon atoms in the formula represented by Cy include R １１ Preferably, Cy is a cycloalkane ring having 5 to 10 carbon atoms, more preferably a cyclopentane ring, a cyclohexane ring, or a cycloheptane ring.

[0099] In the above formulas (2-1) to (2-8), R ７Ａ The divalent organic group having 1 to 20 carbon atoms represented by the above R ８Ａ ~R １３Ａ A group in which one hydrogen atom has been removed from a monovalent organic group having 1 to 20 carbon atoms, represented by the following formula:

[0100] R ７Ａ As the divalent linking group, a single bond, a divalent hydrocarbon group having 1 to 10 carbon atoms, or a combination of a divalent hydrocarbon group having 1 to 10 carbon atoms and a divalent heteroatom-containing linking group is preferred. As the divalent hydrocarbon group having 1 to 10 carbon atoms, a methylene group or an ethanediyl group is preferred. As the divalent heteroatom-containing linking group, -O-, -CO-, or a combination thereof is preferred.

[0101] Specific examples of the repeating unit (2) include repeating units represented by the following formulas (2-1) to (2-16).

[0102]

[0103] In the above formulas (2-1) to (2-16), R ３A is synonymous with the above formula (2).

[0104] When the polymer [A] has a repeating unit (2), the content of the repeating unit (2) in all repeating units constituting the polymer [A] (the total content when multiple types are included) is preferably 40 mol %, more preferably 55 mol %, and even more preferably 65 mol %. The upper limit of this content is preferably 99 mol %, more preferably 90 mol %, and even more preferably 80 mol %. By setting the content of the repeating unit (2) within the above range, solvent resistance and resist pattern rectangularity can be exhibited at high levels.

[0105] The polymer [A] may contain, as other repeating units (excluding those represented by formula (1) or (2) above), repeating units containing a structure that generates acid upon exposure, such as an onium salt structure containing a sulfonate anion and a sulfonium cation, or an onium salt structure containing a sulfonate anion and an iodonium cation, a repeating unit having at least one hydroxy group, or a repeating unit having a fluorine atom. When the polymer [A] contains other repeating units, the lower limit of the content of the other repeating units (the total content when multiple types are present) relative to all repeating units constituting the polymer [A] is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol%. The upper limit of the content is preferably 20 mol%, more preferably 14 mol%, and even more preferably 10 mol%.

[0106] The lower limit of the weight-average molecular weight of the polymer (A) is preferably 2000, more preferably 3000, even more preferably 4000, and particularly preferably 5000. The upper limit of the molecular weight is preferably 15000, more preferably 12000, even more preferably 8000, and particularly preferably 7000. The method for measuring the weight-average molecular weight is as described in the Examples.

[0107] The lower limit of the content of the polymer [A] in the composition for forming a resist underlayer film is preferably 0.05 mass %, more preferably 0.1 mass %, and even more preferably 0.2 mass %, based on the total mass of the polymer [A] and the solvent [B]. The upper limit of the content is preferably 1.5 mass %, more preferably 1.0 mass %, and even more preferably 0.8 mass %, based on the total mass of the polymer [A] and the solvent [B].

[0108] The content of the polymer (A) in the components other than the solvent (B) in the composition for forming a resist underlayer film may be 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0109] [Method for Synthesizing Polymer [A]] The polymer [A] can be synthesized by radical polymerization, ionic polymerization, polycondensation, polyaddition, addition condensation, etc., depending on the type of monomer. For example, when the polymer [A] is synthesized by radical polymerization, the polymer can be synthesized by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator, etc.

[0110] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate, and dimethyl-2,2'-azobis(2-methylpropionate); and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. These radical initiators can be used alone or in combination of two or more.

[0111] As the solvent used in the polymerization, the solvent [B] described below can be suitably used. These solvents used in the polymerization may be used alone or in combination of two or more kinds.

[0112] The reaction temperature in the polymerization is usually 40° C. to 150° C., preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0113] <Solvent (B)> The solvent (B) is not particularly limited as long as it can dissolve or disperse the polymer (A) and any optional components contained as needed.

[0114] Examples of the solvent (B) include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, etc. The solvent (B) can be used alone or in combination of two or more.

[0115] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0116] Examples of ester-based solvents include carbonate-based solvents such as diethyl carbonate, acetate monoester-based solvents such as methyl acetate and ethyl acetate, lactone-based solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate-based solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate-based solvents such as methyl lactate and ethyl lactate.

[0117] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, 4-methyl-2-pentanol, and 2,2-dimethyl-1-propanol, and polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0118] Examples of the ketone solvent include chain ketone solvents such as methyl ethyl ketone, 4-methyl-2-pentanone (methyl isobutyl ketone), and 2-heptanone, and cyclic ketone solvents such as cyclohexanone.

[0119] Examples of ether solvents include chain ether solvents such as n-butyl ether, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0120] Examples of the nitrogen-containing solvent include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0121] The solvent (B) is preferably a ketone solvent, an ether solvent, or an ester solvent, more preferably a cyclic ketone solvent, a polyhydric alcohol partial ether solvent, or a polyhydric alcohol partial ether carboxylate solvent, still more preferably cyclohexanone, propylene glycol monomethyl ether, or propylene glycol monomethyl ether acetate, and particularly preferably propylene glycol monomethyl ether acetate.

[0122] [Optional Components] The composition for forming a resist underlayer film may contain optional components within a range that does not impair the effects of the present invention. Examples of optional components include a crosslinking agent, an acid generator, a dehydrating agent, an acid diffusion controller, a surfactant, a base generator, and an antifoaming agent. Specific examples of base generators include "U-CAT (registered trademark) SA1", "U-CAT (registered trademark) SA102", "U-CAT (registered trademark) SA102-50", "U-CAT (registered trademark) SA106", "U-CAT (registered trademark) SA112", "U-CAT (registered trademark) SA506", "U-CAT (registered trademark) SA603", "U-CAT (registered trademark) SA1000", "U-CAT (registered trademark) SA1102", "U-CAT (registered trademark) SA2000", and "U-CAT (registered trademark) SA603". Examples of such polyimide polymers include "U-CAT (registered trademark) 2024," "U-CAT (registered trademark) 2026," "U-CAT (registered trademark) 2030," "U-CAT (registered trademark) 2110," "U-CAT (registered trademark) 2313," "U-CAT (registered trademark) 651M," "U-CAT (registered trademark) 660M," "U-CAT (registered trademark) 18X," "TMED," "U-CAT (registered trademark) 201G," "U-CAT (registered trademark) 202," "U-CAT (registered trademark) 420A," "U-CAT (registered trademark) 130," "U-CAT 891 (registered trademark)," "POLYCAT (registered trademark) 8," "POLYCAT (registered trademark) 9," "POLYCAT (registered trademark) 12," and "POLYCAT (registered trademark) 41" (all of which are trade names manufactured by San-Apro Ltd.). As the defoaming agent, known defoaming agents can be used, including alcohol defoaming agents, phosphate ester defoaming agents, fatty acid ester defoaming agents, polyether defoaming agents, and silicone defoaming agents. Examples of fatty acid ester defoaming agents include methyl laurate, methyl palmitate, methyl stearate, propyl butyrate, butyl butyrate, ethyl isovalerate, and isobutyl propionate, with propyl butyrate and butyl butyrate being preferred. Ketone solvents such as 2-heptanone may also be used as the defoaming agent. The optional components can be used alone or in combination of two or more. The content of the optional components relative to the total mass of the polymer [A] and the optional components is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0123] [Method for preparing a composition for forming a resist underlayer film] The composition for forming a resist underlayer film can be prepared by mixing the polymer [A], the solvent [B], and, if necessary, any optional components in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter or the like having a pore size of 0.5 μm or less.

[0124] <<Method for Manufacturing Semiconductor Substrate>> The method for manufacturing a semiconductor substrate includes a step of directly or indirectly applying a composition for forming a resist underlayer film onto a substrate (hereinafter also referred to as a "resist underlayer film-forming composition applying step"), a step of forming a resist film on the resist underlayer film formed by the resist underlayer film-forming composition applying step (hereinafter also referred to as a "resist film forming step"), a step of exposing the resist film to radiation (hereinafter also referred to as an "exposure step"), and a step of developing at least the exposed resist film (hereinafter also referred to as a "development step").

[0125] According to the method for producing a semiconductor substrate, by using a predetermined composition for forming a resist underlayer film in the coating step, a resist underlayer film with excellent resist pattern rectangularity can be formed, and therefore a semiconductor substrate with a good pattern shape can be produced.

[0126] The method for producing a semiconductor substrate may further include, as necessary, a step of forming an organic underlayer film directly or indirectly on the substrate (hereinafter also referred to as an "organic underlayer film forming step") prior to the step of applying the composition for forming a resist underlayer film.

[0127] The method for producing a semiconductor substrate may further include, as necessary, a step of forming a silicon-containing film directly or indirectly on the substrate (hereinafter also referred to as a "silicon-containing film-forming step") prior to the step of applying the composition for forming a resist underlayer film.

[0128] Hereinafter, each step in the case where the optional steps of the organic underlayer film forming step and the silicon-containing film forming step are included will be described.

[0129] [Organic Underlayer Film Forming Step] In this step, an organic underlayer film is formed directly or indirectly on the substrate prior to the resist underlayer film forming composition coating step. This step is an optional step. By this step, an organic underlayer film is formed directly or indirectly on the substrate.

[0130] Examples of the substrate include insulating films such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane, and resin substrates. The substrate may also be a substrate patterned with wiring grooves (trenches), plug grooves (vias), and the like.

[0131] The organic underlayer film can be formed by coating an organic underlayer film-forming composition, etc. Examples of methods for forming an organic underlayer film by coating an organic underlayer film-forming composition include a method in which the organic underlayer film-forming composition is directly or indirectly applied to a substrate, and the resulting coating film is heated or exposed to light to cure it. Examples of the organic underlayer film-forming composition that can be used include "HM8006" manufactured by JSR Corporation. The heating and exposure conditions can be appropriately determined depending on the type of organic underlayer film-forming composition used, etc.

[0132] An example of a case where an organic underlayer film is formed indirectly on a substrate is a case where an organic underlayer film is formed on a low dielectric insulating film formed on a substrate.

[0133] [Silicon-containing film forming step] In this step, a silicon-containing film is formed directly or indirectly on a substrate.

[0134] As the substrate, the substrates exemplified in the organic underlayer film forming step can be suitably used.

[0135] The silicon-containing film can be formed by coating a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. Examples of methods for forming a silicon-containing film by coating a silicon-containing film-forming composition include a method in which the silicon-containing film-forming composition is directly or indirectly applied to a substrate, and the resulting coating film is then cured by exposure and / or heating. Examples of commercially available silicon-containing film-forming compositions include "NFC SOG01," "NFC SOG04," and "NFC SOG080" (all from JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxynitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0136] Examples of radiation used for the exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays and gamma rays, and particle beams such as electron beams, molecular beams and ion beams.

[0137] The lower limit of the temperature when heating the coating film is preferably 90° C., more preferably 150° C., and still more preferably 200° C. The upper limit of the temperature is preferably 550° C., more preferably 450° C., and still more preferably 300° C.

[0138] The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and even more preferably 15 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm. The average thickness of the silicon-containing film can be measured in the same manner as the average thickness of the resist underlayer film.

[0139] Examples of cases in which a silicon-containing film is formed indirectly on a substrate include cases in which a silicon-containing film is formed on a low dielectric insulating film or an organic underlayer film formed on a substrate.

[0140] [Resist Underlayer Film-Forming Composition Coating Step] In this step, a resist underlayer film-forming composition is coated onto the organic underlayer film formed on the substrate. The method for coating the resist underlayer film-forming composition is not particularly limited, and can be performed by any appropriate method, such as spin coating, casting coating, or roll coating. This forms a coated film, and the resist underlayer film is formed by volatilization of the solvent (B).

[0141] When the composition for forming a resist underlayer film is applied directly to the substrate, the organic underlayer film forming step may be omitted.

[0142] Next, the coating film formed by the above coating is heated. Heating the coating film promotes the formation of the resist underlayer film. More specifically, heating the coating film promotes the volatilization of the solvent (B).

[0143] The coating film may be heated in an air atmosphere or a nitrogen atmosphere. The lower limit of the heating temperature is preferably 100°C, more preferably 150°C, and still more preferably 200°C. The upper limit of the heating temperature is preferably 400°C, more preferably 350°C, and still more preferably 280°C. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, and more preferably 600 seconds.

[0144] The lower limit of the film thickness (average thickness) of the resist underlayer film formed is preferably 0.5 nm, more preferably 1 nm, and even more preferably 2 nm. The upper limit of the average thickness is preferably 15 nm, more preferably 12 nm, even more preferably 8 nm, and particularly preferably 5 nm. The average thickness is measured as described in the Examples.

[0145] [Resist film forming step] In this step, a resist film is formed on the resist underlayer film formed in the resist underlayer film forming composition applying step. The resist film may be either a coated film or a deposited film, but is preferably a coated film. The method for applying the resist film forming composition is not particularly limited, and examples thereof include a rotary coating method.

[0146] Examples of the resist film-forming composition used in this step include positive or negative chemically amplified resist compositions containing a radiation-sensitive acid generator, positive resist compositions containing an alkali-soluble resin and a quinone diazide photosensitizer, negative resist compositions containing an alkali-soluble resin and a crosslinker, and metal-containing resist film-forming compositions containing a metal such as tin, zirconium, or hafnium. Among these, compositions that are suitable for exposure to extreme ultraviolet rays are preferred, and preferred examples of the resist film-forming composition that can be used include positive or negative chemically amplified resist compositions containing a radiation-sensitive acid generator and metal-containing resist compositions containing a metal such as tin, zirconium, or hafnium.

[0147] The resist film preferably contains a metal. Such a metal-containing resist film is preferably formed from a composition for forming a metal-containing resist film.

[0148] (Composition for forming a metal-containing resist film) The composition for forming a metal-containing resist film contains a metal-containing compound (hereinafter also referred to as "metal-containing compound (A)") and a solvent (hereinafter also referred to as "solvent (F)"), and it is preferable that the content of the metal-containing compound (A) in the composition for forming a metal-containing resist film, other than the solvent (F), is 50 mass % or more. The composition for forming a metal-containing resist film may further contain other components.

[0149] (Metal-Containing Compound (A)) The metal-containing compound (A) is a compound containing a metal atom. The metal-containing compound (A) can be used alone or in combination of two or more. The metal atoms constituting the metal-containing compound (A) can be used alone or in combination of two or more. Here, the term "metal atom" refers to a concept including metalloids, i.e., boron, silicon, germanium, arsenic, antimony, and tellurium.

[0150] The metal atom constituting the metal-containing compound (A) is not particularly limited, and examples thereof include metal atoms of Groups 3 to 16. Specific examples of the metal atom include metal atoms of Group 4 such as titanium, zirconium, and hafnium, metal atoms of Group 5 such as tantalum, metal atoms of Group 6 such as chromium and tungsten, metal atoms of Group 8 such as iron and ruthenium, metal atoms of Group 9 such as cobalt, metal atoms of Group 10 such as nickel, metal atoms of Group 11 such as copper, metal atoms of Group 12 such as zinc, cadmium, and mercury, metal atoms of Group 13 such as boron, aluminum, gallium, indium, and thallium, metal atoms of Group 14 such as germanium, tin, and lead, metal atoms of Group 15 such as antimony and bismuth, and metal atoms of Group 16 such as tellurium.

[0151] The metal atoms constituting the metal-containing compound (A) preferably include a first metal atom belonging to Group 4, Group 12, or Group 14 in the periodic table and belonging to Period 4, Period 5, or Period 6. That is, the metal atom preferably includes at least one of titanium, zirconium, hafnium, zinc, cadmium, mercury, germanium, tin, and lead. Thus, when the metal-containing compound (A) includes a first metal atom, the emission of secondary electrons in the exposed areas of the resist film and the change in the solubility of the metal-containing compound (A) in the developer due to these secondary electrons are further promoted. As a result, the pattern rectangularity can be improved. The first metal atom is preferably tin or zirconium.

[0152] It is preferred that the metal-containing compound (A) further contains other atoms other than metal atoms.These other atoms include, for example, carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms, phosphorus atoms, sulfur atoms, halogen atoms, etc., and among these, carbon atoms, hydrogen atoms, and oxygen atoms are preferred.The other atoms in the metal-containing compound (A) can be used alone or in combination of two or more.

[0153] The lower limit of the content of the metal-containing compound (A) in the composition for forming a metal-containing resist film, calculated as solid content, is preferably 70 mass %, more preferably 90 mass %, and even more preferably 95 mass %. The content may be 100 mass %. Here, the solid content in the composition for forming a metal-containing resist film refers to components other than the solvent (F), which will be described later.

[0154] (Method for synthesizing metal-containing compound (A)) The metal-containing compound (A) can be obtained by, for example, subjecting a metal compound having a metal atom and a hydrolyzable group, a hydrolysate of this metal compound, a hydrolysis condensate of the metal compound, or a combination thereof to a hydrolysis condensation reaction, a ligand exchange reaction, or the like. The metal compounds can be used alone or in combination of two or more.

[0155] The metal-containing compound (A) is preferably derived from a metal compound having a metal atom and a hydrolyzable group represented by the following formula (4) (hereinafter also referred to as "metal compound precursor (1)"). By using such a metal compound precursor (1), a stable metal-containing compound (A) can be obtained.

[0156] In the above formula (4), M is a metal atom. Ａ is a ligand or a monovalent organic group having 1 to 20 carbon atoms. a1 is an integer of 0 to 6. When a1 is 2 or more, a plurality of L １ may be the same or different. Y is a monovalent hydrolyzable group. b1 is an integer of 2 to 6. Multiple Ys may be the same or different. Ａ is a ligand or organic group that does not fall under Y.

[0157] In this specification, the term "organic group" means a group containing at least one carbon atom, and the term "number of carbon atoms" means the number of carbon atoms constituting the group.

[0158] The metal atom represented by M is preferably a metal atom of Group 14, more preferably tin.

[0159] The hydrolyzable group represented by Y can be appropriately changed depending on the metal atom represented by M, and examples thereof include a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, and a substituted or unsubstituted amino group.

[0160] The substituent in the substituted or unsubstituted ethynyl group and the substituted or unsubstituted amino group represented by Y is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a chain hydrocarbon group, and still more preferably an alkyl group.

[0161] Examples of the halogen atom represented by Y include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, a chlorine atom is preferred.

[0162] Examples of the alkoxy group represented by Y include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, etc. Among these, an ethoxy group, an i-propoxy group, and an n-butoxy group are preferred.

[0163] Examples of the acyloxy group represented by Y include a formyl group, an acetoxy group, an ethyloxy group, a propionyloxy group, an n-butyryloxy group, a t-butyryloxy group, a t-amylyloxy group, an n-hexanecarbonyloxy group, an n-octanecarbonyloxy group, etc. Among these, an acetoxy group is preferred.

[0164] Examples of the substituted or unsubstituted amino group represented by Y include an amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dipropylamino group, etc. Among these, a dimethylamino group and a diethylamino group are preferred.

[0165] Hereinafter, a preferred combination of a metal atom represented by M and a hydrolyzable group represented by Y will be described. When the metal atom represented by M is tin, the hydrolyzable group represented by Y is preferably a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, and a substituted or unsubstituted amino group, and more preferably a halogen atom. When the metal atom represented by M is germanium, the hydrolyzable group represented by Y is preferably a halogen atom, an alkoxy group, an acyloxy group, and a substituted or unsubstituted amino group. When the metal atom represented by M is hafnium, zirconium, or titanium, the hydrolyzable group represented by Y is preferably a halogen atom, an alkoxy group, or an acyloxy group.

[0166] L Ａ The ligand represented by the formula (I) includes a monodentate ligand and a polydentate ligand.

[0167] Examples of the monodentate ligand include a hydroxo ligand, a nitro ligand, and ammonia.

[0168] Examples of the polydentate ligand include hydroxy acid esters, β-diketones, β-ketoesters, malonic acid diesters in which the carbon atom at the α-position may be substituted, and hydrocarbons having a π bond, or ligands derived from these compounds, and diphosphines.

[0169] Examples of the diphosphines include 1,1-bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, and 1,1'-bis(diphenylphosphino)ferrocene.

[0170] L Ａ The monovalent organic group represented by the formula (A1) is R １１ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0171] L Ａ The lower limit of the number of carbon atoms of the monovalent organic group represented by the formula (I) is preferably 2, more preferably 3. On the other hand, the upper limit of the number of carbon atoms is preferably 10, more preferably 5.１ The monovalent organic group represented by the formula (I) is preferably a substituted or unsubstituted hydrocarbon group, more preferably a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group, further preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted aralkyl group, and particularly preferably an isopropyl group or a benzyl group.

[0172] As a1, 1 and 2 are preferred, and 1 is more preferred.

[0173] b1 is preferably an integer of 2 to 4. By setting b1 to the above-mentioned value, the content of metal atoms in the metal-containing compound (A) can be increased, and the generation of secondary electrons by the metal-containing compound (A) can be more effectively promoted. As a result, the pattern rectangularity can be improved.

[0174] The metal compound precursor (1) is preferably a metal halide compound, more preferably isopropyltin trichloride or benzyltin trichloride.

[0175] Examples of methods for carrying out the hydrolysis condensation reaction of the metal compound precursor (1) include stirring the metal compound precursor (1) in water or a solvent containing water in the presence of a base such as tetramethylammonium hydroxide, which is used as needed. In this case, other compounds having hydrolyzable groups may be added as needed. The lower limit of the amount of water used in this hydrolysis condensation reaction is preferably 0.2 times by mole, more preferably 1 time by mole, and even more preferably 3 times by mole, relative to the hydrolyzable groups of the metal compound precursor (1) or the like. By setting the amount of water in the hydrolysis condensation reaction within the above range, the metal-containing compound (A) can be efficiently obtained.

[0176] In the synthesis reaction of the metal-containing compound (A), in addition to the metal compound precursor (1), L in the compound of the above formula (4) Ａ Alternatively, a compound capable of becoming a multidentate ligand represented by the formula (I) or a compound capable of becoming a bridging ligand may be added. Examples of the compound capable of becoming a bridging ligand include compounds having two or more coordinating groups such as a hydroxy group, an isocyanate group, an amino group, an ester group, and an amide group.

[0177] The lower limit of the temperature for the synthesis reaction of the metal-containing compound (A) is preferably 0° C., more preferably 10° C. The upper limit of the temperature is preferably 150° C., more preferably 100° C., and even more preferably 50° C.

[0178] The lower limit of the synthesis reaction time of the metal-containing compound (A) is preferably 1 minute, more preferably 10 minutes, and even more preferably 1 hour. The upper limit of the synthesis reaction time is preferably 100 hours, more preferably 50 hours, even more preferably 24 hours, and particularly preferably 4 hours.

[0179] (Solvent (F)) The solvent (F) is preferably an organic solvent. Specific examples of this organic solvent include the same solvents as those exemplified as the solvent (B) in the composition for forming a resist underlayer film.

[0180] As the solvent (F), an ether solvent is preferred, and propylene glycol monoethyl ether is more preferred.

[0181] (Other Optional Components) The composition for forming a metal-containing resist film may contain other optional components such as a compound that can serve as a ligand, a surfactant, and the like, in addition to the metal-containing compound (A) and the solvent (F).

[0182] (Compound that can be a ligand) Examples of the compound that can be a ligand include compounds that can be polydentate ligands or bridging ligands, and specific examples include the same compounds that can be polydentate ligands or bridging ligands as exemplified in the synthesis method for the metal-containing compound (A).

[0183] (Surfactant) The surfactant is a component that acts to improve application properties, striations, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate, as well as KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and the like, which are trade names hereinafter. 95 (all manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products Co., Ltd.), Megafac F171, F173 (all manufactured by Dainippon Ink and Chemicals, Inc.), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M Limited), Asahiguard AG710, Surflon S-382, Surflon SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.), and the like.

[0184] To explain this step in more detail, for example, a resist composition is applied so that the resist film to be formed has a predetermined thickness, and then the applied resist film is pre-baked (hereinafter also referred to as "PB") to volatilize the solvent in the applied film, thereby forming the resist film.

[0185] The PB temperature and PB time can be appropriately determined depending on the type of the resist film-forming composition used, etc. The lower limit of the PB temperature is preferably 30°C, more preferably 50°C. The upper limit of the PB temperature is preferably 200°C, more preferably 150°C. The lower limit of the PB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PB time is preferably 600 seconds, more preferably 300 seconds.

[0186] [Exposure Step] In this step, the resist film is exposed to radiation.

[0187] The radiation used for exposure can be appropriately selected depending on the type of the resist film-forming composition used, etc. Examples include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and gamma rays, and particle beams such as electron beams, molecular beams, and ion beams. Among these, electron beams or far ultraviolet light are preferred, and electron beams, KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ２ Excimer laser light (wavelength 157 nm), Kr ２ Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., also referred to as "EUV") is more preferred, and electron beam or EUV is even more preferred. The exposure conditions can be appropriately determined depending on the type of the resist film-forming composition used, etc.

[0188] Furthermore, in this process, after the exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined depending on the type of resist film-forming composition used, etc. The lower limit of the PEB temperature is preferably 50°C, more preferably 70°C. The upper limit of the PEB temperature is preferably 200°C, more preferably 150°C. The lower limit of the PEB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PEB time is preferably 600 seconds, more preferably 300 seconds.

[0189] [Development Step] In this step, at least the exposed resist film is developed. At this time, a portion of the resist underlayer film may also be developed. The development may be performed by dissolving the resist film in a developer or by volatilizing the resist film by heating or reducing pressure, depending on the type of the resist film-forming composition. This allows the formation of a resist pattern.

[0190] When the developer is used, examples of the developer include an aqueous alkaline solution (alkaline developer) and a liquid containing an organic solvent (organic solvent developer).

[0191] The basic liquid for alkaline development is not particularly limited, and a known basic liquid can be used. Examples of the basic liquid for alkaline development include an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0192] Examples of organic solvent developers for use in organic solvent development include those exemplified above as the solvent [B]. As the organic solvent developer, an ester solvent, an ether solvent, an alcohol solvent, a ketone solvent, and / or a hydrocarbon solvent is preferred, a ketone solvent is more preferred, and 2-heptanone is particularly preferred.

[0193] In this step, washing and / or drying may be performed after the development. Furthermore, etching may be performed using the resist pattern as a mask. Examples of etching methods include dry etching and wet etching.

[0194] The polymer has at least one group that generates a radical upon irradiation with radiation, the group being selected from the group consisting of the above formulae (A1) to (A8). As the polymer, the polymer (A) in the above composition for forming a resist underlayer film can be suitably used.

[0195] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0196] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured by gel permeation chromatography (detector: differential refractometer) using GPC columns (two "G2000HXL" and one "G3000HXL" columns) manufactured by Tosoh Corporation under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C, with monodisperse polystyrene as the standard.

[0197] [Average Film Thickness] The average film thickness was determined by measuring the film thickness at 9 arbitrary positions at 5 cm intervals, including the center of the resist underlayer film formed on a silicon wafer (substrate), using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"), and calculating the average of these film thicknesses.

[0198] <Synthesis of Polymer [A] and Comparative Polymer> Polymer [A] having repeating units represented by the following formulae (A-1) to (A-35) was synthesized according to the procedure shown below. Also, a comparative polymer having a repeating unit represented by the following formula (CA-1) was synthesized. In the following formulae, the number attached to each repeating unit indicates the content (mol %) of that repeating unit. The composition ratio is １３ This was confirmed by C-NMR.

[0199]

[0200]

[0201]

[0202]

[0203]

[0204]

[0205] The following compounds (a1-1) to (a1-6), (a2-1) to (a2-2), (a3-1) to (a3-4), (a4-1) to (a4-5), (a5-1) to (a5-7), (a6-1), (a7-1) to (a7-6), and (a8-1) (hereinafter also referred to as “compound (a)”)), as monomers, were used in the synthesis of polymer (A) and comparative polymer.

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215] Example A1-1 Synthesis of Polymer (A-1) 6 g of 4-methyl-2-pentanone was placed in a reaction vessel and maintained at 80°C, and a mixture of 1.69 g of compound (a5-1), 4.31 g of compound (b-1), 1.35 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 4-methyl-2-pentanone was added dropwise from a feeder over 3 hours. After completion of the dropwise addition, the mixture was stirred at 80°C for 3 hours. The resulting polymerization solution was purified by precipitation with a 5-fold amount of heptane, yielding 5.2 g of polymer (A-1) as a white solid.

[0216] [Examples A1-2 to A1-35 and Comparative Example A1-1] (Synthesis of Polymers (A-2) to (A-35) and Comparative Polymer (CA-1)) Polymers (A-2) to (A-35) and Comparative Polymer (CA-1) were synthesized in the same manner as for Polymer (A-1), except that the types and amounts of Compound [a] and Compound [b] shown in Table 1 were used. The Mw and Mn of the obtained Polymer [A] and Comparative Polymer (CA-1) are also shown in Table 1. In the table, "-" indicates that the corresponding component was not used. The same applies to the subsequent tables.

[0217]

[0218] <Preparation of Composition for Forming Resist Underlayer Film> The polymer (A), the solvent (B), and the comparative polymer (CA-1) used in preparing the composition for forming a resist underlayer film (hereinafter also referred to as "composition") are shown below.

[0219] [[A] Polymer] A-1 to A-35: Polymers (A-1) to (A-35) synthesized above

[0220] [Comparative Polymer (CA-1)] CA-1: Polymer (CA-1) synthesized above

[0221] [B] Solvent B-1: Propylene glycol monomethyl ether acetate

[0222] [Example 1-1] 100 parts by mass of (A-1) as a polymer [A] was dissolved in 20,000 parts by mass of (B-1) as a solvent [B]. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare a composition (J-1).

[0223] [Examples 1-2 to 1-35 and Comparative Example 1-1] Compositions (J-2) to (J-35) and (CJ-1) were prepared in the same manner as in Example 1-1, except that the types and amounts of each component shown in Table 2 below were used.

[0224]

[0225] <Evaluation> Using the compositions prepared above, the rectangularity of resist patterns formed by EUV exposure using chemically amplified resist compositions was evaluated by the following method. The evaluation results are shown in Table 3 below.

[0226] <Preparation of Resist Composition> Resist composition (R-1) was obtained by mixing 100 parts by mass of a polymer having a structural unit (1) derived from 4-hydroxystyrene, a structural unit (2) derived from styrene, and a structural unit (3) derived from 4-t-butoxystyrene (the proportions of the structural units were (1) / (2) / (3)=65 / 5 / 30 (mol %)), 1.0 part by mass of triphenylsulfonium trifluoromethanesulfonate as a radiation-sensitive acid generator, and 4,400 parts by mass of ethyl lactate and 1,900 parts by mass of propylene glycol monomethyl ether acetate as solvents, and filtering the resulting solution through a filter with a pore size of 0.2 μm.

[0227] [Resist pattern rectangularity (EUV exposure)] An organic underlayer film forming material (JSR Corporation's "HM8006") was applied to a 12-inch silicon wafer by a spin coating method using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. A silicon-containing film-forming composition (JSR Corporation's "NFC SOG080") was applied to this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a silicon-containing film with an average thickness of 20 nm. The composition prepared above was applied to the silicon-containing film formed above to form a resist underlayer film. The resist underlayer film formed above was heated at 250°C for 90 seconds, and then cooled at 23°C for 30 seconds to obtain a resist underlayer film with an average thickness of 5 nm. Resist composition (R-1) was applied onto the resist underlayer film formed above, heated at 130° C. for 60 seconds, and then cooled at 23° C. for 30 seconds to form a resist film with an average thickness of 50 nm. Next, the resist film was irradiated with extreme ultraviolet rays using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line and space mask with a line width of 16 nm on the wafer). After irradiation with extreme ultraviolet rays, the substrate was heated at 110°C for 60 seconds and then cooled at 23°C for 60 seconds. Thereafter, the substrate was developed by the puddle method using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (20°C to 25°C), followed by washing with water and drying to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Technologies Corporation's "SU8220") was used to measure and observe the resist pattern of the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, and as "B" (poor) when there was a footing on the cross-section of the pattern.

[0228]

[0229] <Evaluation> Using the compositions prepared above, the rectangularity of resist patterns formed by EUV exposure using the compositions for forming metal-containing resist films was evaluated by the following method. The evaluation results are shown in Table 4 below.

[0230] <Preparation of Resist Composition (R-2)> Compound (S-1) used in preparing resist composition (R-2) was synthesized according to the following procedure. In a reaction vessel, 6.5 parts by mass of isopropyltin trichloride was added to 150 mL of 0.5 N aqueous sodium hydroxide solution while stirring, and the mixture was stirred for 2 hours. The precipitate was collected by filtration, washed twice with 50 parts by mass of water, and then dried to obtain compound (S-1). Compound (S-1) was an oxide hydroxide product (i-PrSnO) of the hydrolysis product of isopropyltin trichloride. （３／２-ｘ／２） (OH) ｘ (where 0<x<3 is the structural unit).

[0231] 2 parts by mass of the compound (S-1) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the resulting mixture was passed through an activated 4 Å molecular sieve to remove residual water, followed by filtration through a filter with a pore size of 0.2 μm to prepare resist composition (R-2).

[0232] [Resist Pattern Rectangularity (EUV Exposure)] A material for forming an organic underlayer film ("HM8006" manufactured by JSR Corporation) was applied onto a 12-inch silicon wafer by spin coating using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. The resist underlayer film-forming composition prepared above was applied onto this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film with an average thickness of 5 nm. Resist composition (R-2) was applied onto this resist underlayer film by spin coating using the spin coater, and after a predetermined time had elapsed, heated at 90°C for 60 seconds and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 35 nm. The resist film was exposed to light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line and space mask with on-wafer line width of 16 nm). After exposure, the substrate was heated at 110°C for 60 seconds and then cooled at 23°C for 60 seconds. Thereafter, the substrate was developed using 2-heptanone (20 to 25°C) by a puddle method and then dried to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Tech's "CG-6300") was used to measure and observe the resist pattern of the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, and as "B" (poor) when there was footing on the cross-section of the pattern.

[0233]

[0234] As can be seen from the results in Tables 3 and 4, the resist underlayer films formed from the compositions of the Examples were superior in resist pattern rectangularity compared to the resist underlayer films formed from the compositions of the Comparative Examples.

[0235] The composition for forming a resist underlayer film of the present invention can form a film with excellent resist pattern rectangularity. The method for producing a semiconductor substrate of the present invention uses a composition for forming a resist underlayer film that can form a resist underlayer film with excellent resist pattern rectangularity, allowing for efficient production of semiconductor substrates. The polymer of the present invention can be suitably used as a component of the composition for forming a resist underlayer film. Therefore, these can be suitably used in the production of semiconductor devices, etc.

Claims

1. A composition for forming a resist underlayer film, comprising: a polymer having a group that generates a radical upon irradiation with radiation; and a solvent.

2. The composition for forming a resist underlayer film according to claim 1, wherein the polymer has at least one group selected from the group consisting of the following formulae (A1) to (A8) that generates a radical upon irradiation with radiation: (In the above formulas (A-1) to (A-8), R １ ~R １０ and R １２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. １１ is a monovalent organic group having 1 to 20 carbon atoms. ａ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, and R ｂ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｃ R is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｄ and R ｅ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, or R ｄ and R ｅ are combined with each other to form a divalent alicyclic group having 3 to 10 carbon atoms together with the carbon atoms to which they are attached. １ are each independently a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. ｆ is a monovalent organic group having 1 to 20 carbon atoms. ｇ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. ｇ In the formula (A7), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. ｈ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ｈ In the formula (A8), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. * indicates a bond to another part of the polymer.

3. The composition for forming a resist underlayer film according to claim 1, wherein the polymer has a repeating unit represented by the following formula (1): (In the above formula (1), R ０ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group with a valence of 1+n. X is a group that generates a radical upon irradiation with radiation. n is an integer of 1 to 5. When n is 2 or more, multiple Xs are the same or different.

4. The composition for forming a resist underlayer film according to claim 3, wherein X in the formula (1) is at least one group selected from the group consisting of the following formulae (A-1) to (A-8): (In the above formulas (A1) to (A8), R １ ~R １０ and R １２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. １１ is a monovalent organic group having 1 to 20 carbon atoms. ａ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, and R ｂ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｃ R is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｄ and R ｅ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, or R ｄ and R ｅ are combined with each other to form a divalent alicyclic group having 3 to 10 carbon atoms together with the carbon atoms to which they are attached. １ are each independently a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. ｆ is a monovalent organic group having 1 to 20 carbon atoms. ｇ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. ｇ In the formula (A7), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. ｈ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ｈ In the formula (A8), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. * indicates L in the formula (1). １ It is a bond with 5. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the content of the repeating unit represented by formula (1) in all repeating units constituting the polymer is 1 mol % or more.

6. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the polymer further has a repeating unit represented by the following formula (2): (In formula (2), R ３Ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３Ａ is a single bond or a divalent linking group. ４Ａ is a group selected from the group consisting of groups represented by any one of the following formulas (2-1) to (2-8): (In formulas (2-1) to (2-3), (2-7), R ８Ａ , R ９Ａ , R １０Ａ , R １２Ａ and R １３Ａ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (2-2), Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in the formula. R １１Ａ is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. ** is a bond to an atom constituting Cy. However, R １１Ａ is a single bond, R １１Ａ In formulas (2-1) to (2-8), R ７Ａ is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３Ａ is the bond to the atoms that make up the atom.) 7. The composition for forming a resist underlayer film according to any one of claims 1 to 4, which is a composition for forming an underlayer film of a resist film to be exposed to extreme ultraviolet rays.

8. The composition for forming a resist underlayer film according to claim 7, wherein the resist film contains a metal.

9. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the resist underlayer film has a film thickness of 5 nm or less.

10. A method for producing a semiconductor substrate, comprising: a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate; a step of forming a resist film on the resist underlayer film formed by the step of applying the composition for forming a resist underlayer film; a step of exposing the resist film to radiation; and a step of developing at least the exposed resist film, wherein the composition for forming a resist underlayer film contains a polymer having a group that generates a radical upon irradiation with radiation, and a solvent.

11. The method for manufacturing a semiconductor substrate according to claim 10, wherein said radiation is extreme ultraviolet radiation.

12. The method for producing a semiconductor substrate according to claim 10 or 11, wherein the resist film-forming composition contains a metal.

13. The method for producing a semiconductor substrate according to claim 10 or 11, wherein the resist underlayer film has a film thickness of 5 nm or less.

14. A polymer having at least one group that generates a radical upon irradiation with radiation, selected from the group consisting of the following formulae (A1) to (A8): (In the above formulas (A-1) to (A-8), R １ ~R １０ and R １２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. １１ is a monovalent organic group having 1 to 20 carbon atoms. ａ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, and R ｂ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ａ and R ｂ At least one selected from the group consisting of is a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｃ R is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｄ and R ｅ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, or R ｄ and R ｅ are combined with each other to form a divalent alicyclic group having 3 to 10 carbon atoms together with the carbon atoms to which they are attached. １ are each independently a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. ｆ is a monovalent organic group having 1 to 20 carbon atoms. ｇ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. ｇ In the formula (A7), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. ｈ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ｈ In the formula (A8), at least one hydrogen atom is bonded to the carbon atom at the α-position or β-position relative to N. * indicates a bond to another part of the polymer.

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