Semiconductor substrate production method and composition for forming resist underlayer film

Abstract

Provided are a semiconductor substrate production method and a composition for forming a resist underlayer film that make it possible to form a resist underlayer film capable of exhibiting excellent pattern rectangularity and pattern defect suppression when forming a resist pattern. The semiconductor substrate production method comprises: a step in which a substrate is directly or indirectly coated with the composition for forming a resist underlayer film; a step in which a resist film is formed on the resist underlayer film formed by the step in which coating is performed with the composition for forming a resist underlayer film; a step in which the resist film is exposed to radiation; and a step in which at least the exposed resist film is developed. The composition for forming a resist underlayer film contains a polymer and a solvent. The polymer includes a repeating unit (1) represented by formula (1). (In formula (1), R1 represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1-20 carbon atoms. L1 represents a single bond or a divalent linking group. R2 is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium.)

Description

Semiconductor substrate manufacturing method and composition for forming resist underlayer film

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

[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 in such EUV exposure (see JP 2023-94359 A).

[0004] JP 2023-94359 A

[0005] As resist patterns formed by exposure to extreme ultraviolet light and development continue to become finer, there is a demand for pattern rectangularity, which ensures rectangularity of the resist pattern by suppressing pattern footing at the bottom of the resist film, as well as pattern defect suppression, which suppresses the occurrence of residue defects in 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 method for producing a semiconductor substrate and a composition for forming a resist underlayer film, which are capable of forming a resist underlayer film that can exhibit excellent pattern rectangularity and pattern defect suppression properties during resist pattern formation.

[0007] In one embodiment, the present invention relates to a method for producing a semiconductor substrate, the method 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 (hereinafter also referred to as "polymer [A]") and a solvent (hereinafter also referred to as "solvent [B]"), and the polymer contains a repeating unit (1) represented by the following formula (1): (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a single bond or a divalent linking group. ２ is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium (hereinafter also referred to as "specific metal atom").

[0008] This method for producing a semiconductor substrate allows the formation of a resist underlayer film that exhibits excellent pattern rectangularity and pattern defect suppression during resist pattern formation. While the reason for this is unclear, it is presumed as follows. For example, when a resist underlayer film-forming composition containing a polymer having a hydrophilic moiety is applied to a substrate having a hydrophobic surface, if the influence of the difference in physical properties between the resist underlayer film-forming composition and the substrate cannot be ignored, the polymer may aggregate, reducing the dispersibility of each component, including the polymer, in the coated film. This can result in variations in the performance required of the resist underlayer film depending on the location, and the desired effects of the resist underlayer film may not be achieved. In this method for producing a semiconductor substrate, a polymer containing a repeating unit (1) containing a specific metal atom is used in the resist underlayer film-forming composition, making the polymer relatively rigid and reducing the mobility of the polymer, thereby preventing polymer aggregation and allowing for good dispersion of each component. Furthermore, the introduction of a metal atom improves affinity with the substrate, resulting in improved coatability. It is presumed that the above-mentioned effects are achieved as a result of the combined effects of these actions.

[0009] In another embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a polymer; and a solvent, wherein the polymer contains a repeating unit (1) represented by the following formula (1): (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a single bond or a divalent linking group. ２ is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium.

[0010] As used herein, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed solely of a linear structure, including both linear and branched hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, including both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not necessarily have to be composed solely of an alicyclic structure, and may contain a linear structure as part of it). The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure (however, it does not necessarily have to be composed solely of an aromatic ring structure, and may contain an alicyclic structure or a linear structure as part of it). The term "organic group" as used herein refers to a group having at least one carbon atom. The term "number of ring members" as used herein refers to the number of atoms constituting the ring. For example, a biphenyl ring has 12 ring members, a naphthalene ring has 10 ring members, and a fluorene ring has 13 ring members.

[0011] According to the method for producing a semiconductor substrate, a composition for forming a resist underlayer film is used that can form a resist underlayer film that can exhibit excellent pattern rectangularity and suppress pattern defects during resist pattern formation, allowing for efficient production of semiconductor substrates. The composition for forming a resist underlayer film can form a resist underlayer film that can exhibit excellent pattern rectangularity and suppress pattern defects during resist pattern formation. Therefore, these compositions can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0012] Hereinafter, the method for producing a semiconductor substrate and the composition for forming a resist underlayer film according to each embodiment of the present invention will be described in detail. In the embodiments, a combination of preferred aspects is also preferred.

[0013] <<Method for Manufacturing Semiconductor Substrate>> The method for manufacturing a semiconductor substrate includes a step of applying a composition for forming a resist underlayer film directly or indirectly to 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").

[0014] According to the method for producing a semiconductor substrate, by using a predetermined composition for forming a resist underlayer film in the resist underlayer film-forming composition application step, a resist underlayer film can be formed that can exhibit excellent pattern rectangularity and pattern defect suppression properties during resist pattern formation, and therefore a semiconductor substrate with a good pattern shape can be produced.

[0015] 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.

[0016] 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.

[0017] Hereinafter, a resist underlayer film-forming composition used in the method for producing a semiconductor substrate, and each of the optional steps of the organic underlayer film-forming step and the silicon-containing film-forming step will be described.

[0018] <Composition for forming a resist underlayer film> The composition for forming a resist underlayer film (hereinafter also referred to as "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. By containing the polymer [A] and the solvent [B], the composition for forming a resist underlayer film can form a resist underlayer film that can exhibit excellent pattern rectangularity and pattern defect suppression during resist pattern formation.

[0019] <Polymer [A]> The polymer [A] contains a repeating unit (1). The polymer [A] may contain other repeating units in addition to these repeating units. The polymer [A] may have one or more types of repeating unit (1). The composition can contain one or more types of polymer [A]. The polymer [A] is preferably an acrylic polymer.

[0020] (Repeating Unit (1)) The repeating unit (1) is represented by the following formula (1). (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a single bond or a divalent linking group. ２ is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium.

[0021] R １ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

[0022] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group; alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0023] 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.

[0024] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group.

[0025] R １ 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, or a butyryl group, a cyano group, a nitro group, and a hydroxy group.

[0026] R １ In terms of copolymerizability of the monomer that gives the repeating unit (1), a hydrogen atom or a methyl group is preferred.

[0027] L １ Suitable divalent linking groups include, for example, divalent hydrocarbon groups, -CO-, -O-, -S-, -CO-, -NR'-, and combinations thereof, where R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0028] L １ The divalent hydrocarbon group in R １ A group in which one hydrogen atom has been removed from a monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the following formula: １The divalent hydrocarbon group in is preferably a divalent chain hydrocarbon group or a divalent aromatic hydrocarbon group, and more preferably a methylene group, an ethanediyl group, a propanediyl group, a benzenediyl group, or a naphthalenediyl group.

[0029] L １ Examples of the divalent linking group represented by the formula: ＊ , a propanediyl group, a benzenediyl group, or a combination thereof is preferred. * represents R in the above formula (1). ２ It is the connecting hand on the side.

[0030] R ２ The monovalent group containing a specific metal atom represented by the formula (I) is not particularly limited as long as it contains a specific metal atom, and examples thereof include monovalent organic groups containing a specific metal atom and having 1 to 20 carbon atoms. Examples of monovalent organic groups containing 1 to 20 carbon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups having a divalent heteroatom-containing linking group between carbon atoms in the hydrocarbon group or at the end of the hydrocarbon group, groups in which some or all of the hydrogen atoms in the hydrocarbon group have been substituted with monovalent heteroatom-containing substituents, and combinations thereof.

[0031] The monovalent hydrocarbon group having 1 to 20 carbon atoms includes the above-mentioned R １ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0032] 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.

[0033] 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.

[0034] Examples of the monovalent heteroatom-containing substituent include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0035] The specific metal atom is preferably incorporated into the organic group by substituting one or more carbon atoms constituting the organic group. In this case, it should be understood that the number of bonds to the specific metal atom of the organic group is determined depending on the valence of the specific metal atom.

[0036] R ２ The specific metal atom in １ It is preferably directly bonded to

[0037] R ２ is preferably a group represented by the following formula (a): (In formula (a), M is a silicon atom, zinc atom, aluminum atom, germanium atom, tin atom, titanium atom, zirconium atom, or hafnium atom. R ２ａ is a monovalent organic group having 1 to 20 carbon atoms. ２ａ If there are multiple R ２ａ are each independently a monovalent organic group having 1 to 20 carbon atoms, or a plurality of R ２ａ Two of them are combined with each other to form a ring structure together with the M to which they are attached. k is the value obtained by subtracting 1 from the valence value of the atom represented by M. * is L １ It is a bond with

[0038] M is preferably a silicon atom or a tin atom.

[0039] R ２ａ The monovalent organic group having 1 to 20 carbon atoms represented by the above R ２ A monovalent organic group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0040] R ２ａ The ring structure formed when a plurality of R １A structure in which one of the ring-constituting carbon atoms of a ring structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the formula (I) above is substituted with M can be preferably employed. The divalent heteroatom-containing linking group may be present between carbon atoms of the ring structure.

[0041] R ２ａ is preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. １ The alkyl group shown in the above can be preferably used. Examples of the alkoxy group include alkoxy groups having 1 to 10 carbon atoms, such as a methoxy group, an ethoxy group, and a propoxy group. When the alkyl group or alkoxy group has a substituent, the substituent may be any of the groups shown in the above R １ The substituents that may be possessed by the group may be suitably employed.

[0042] R ２ａ is preferably a substituted or unsubstituted alkyl group, more preferably an unsubstituted linear alkyl group, and further preferably a methyl group, an ethyl group, an n-propyl group, or an n-butyl group.

[0043] Specific examples of compounds that provide the repeating unit (1) include compounds represented by the following formulas (1-1) to (1-16).

[0044] (In the formula, Me represents a methyl group and Et represents an ethyl group. The same applies hereinafter.)

[0045] The lower limit of the content of the repeating unit (1) in all repeating units constituting the polymer (total content when multiple types of repeating unit (1) are present) is preferably 1 mol%. The lower limit of the content may be 3 mol%, 5 mol%, 8 mol%, or 10 mol%. The upper limit of the content is preferably 90 mol%, more preferably 60 mol%, even more preferably 50 mol%, and particularly preferably 40 mol%. By setting the content of the repeating unit (1) within the above range, the composition can exhibit excellent pattern rectangularity and pattern defect suppression during resist pattern formation.

[0046] (Repeating Unit (2)) The polymer [A] preferably further contains a repeating unit (2) having an organic sulfonate anion moiety and an onium cation moiety. The organic sulfonate anion moiety and the onium cation moiety form an onium salt structure, which generates an acid (sulfonic acid) upon exposure. The form in which the organic sulfonate anion moiety and the onium cation moiety are contained is not particularly limited. The organic sulfonate anion moiety may be bonded to the polymer chain of the polymer [A] and the onium cation moiety may be contained as its counter ion, or the onium cation moiety may be bonded to the polymer chain of the polymer [A] and the organic sulfonate anion moiety may be contained as its counter ion.

[0047] When the polymer (A) is an acrylic polymer, the repeating unit (2) is preferably a repeating unit represented by the following formula (2-1) or (2-2) (hereinafter, also referred to as “repeating unit (2-1)”): (In formula (2-1), R ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２ is a divalent linking group. ３ is a single bond or a divalent organic group having 1 to 40 carbon atoms. １ ＋ is a monovalent onium cation. ａ and L ３are R in the above formula (2-1), ａ and L ２ It is synonymous with Z. ２ ＋ is a monovalent group having a monovalent onium cation structure. ４ is a monovalent organic group having 1 to 40 carbon atoms.

[0048] In the repeating unit (2-1), the organic sulfonate anion moiety (-R ３ SO ３ - ) is bonded to the polymer chain (side chain) of the polymer [A], and the onium cation moiety (Z １ ＋ In the repeating unit (2-2), an onium cation moiety (-Z ２ ＋ ) is bonded to the polymer chain (side chain) of the polymer [A], and the organic sulfonate anion moiety (R ４ SO ３ - ) is contained as its counter ion.

[0049] R in the above formulas (2-1) and (2-2) ａ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is １ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0050] R ａ When R has a substituent, the substituent is R １ The substituents that may be possessed by the group may be suitably employed.

[0051] Among them, R ａ In view of the copolymerizability of the monomer that gives the repeating unit (2), a hydrogen atom or a methyl group is preferred.

[0052] In the above formulas (2-1) and (2-2), L ２ and L ３ As the divalent linking group represented by the formula (I), for example, a divalent hydrocarbon group, —COO—, —OCO—, —O—CO—O—, —CONH—, —O—, —S—, —CO—, or a group formed by combining these can be suitably used.

[0053] L ２ and L ３ The divalent hydrocarbon group in R ａ Among these, groups in which one hydrogen atom has been removed from a monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the following formula: ２ and L ３ Preferably, the group contains a divalent aromatic ring, and more preferably contains a benzenediyl group or a naphthalenediyl group.

[0054] R in the above formula (2-1) ３ The divalent organic group having 1 to 40 carbon atoms represented by the formula (2-2) is R ４ Therefore, first, R in the above formula (2-2) is ４ The monovalent organic group having 1 to 40 carbon atoms and represented by the following formula will be described.

[0055] R in the above formula (2-2) ４ The monovalent organic group having 1 to 40 carbon atoms represented by the formula (1) is R ２ A group in which the number of carbon atoms of the monovalent organic group having 1 to 20 carbon atoms shown in the above formula (I) is extended to 40 can be suitably used.

[0056] The above R ４ The organic sulfonate anion moiety containing the sulfonate ion (SO ) is preferably represented by the following formula (p-1): ３ - ) is R ４ Corresponds to. (In the above formula (p-1), R ｐ１ is a monovalent group containing a ring structure having 5 or more ring members. ｐ２ is a divalent organic group. ｐ３ and R ｐ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ｐ５ and R ｐ６ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.ｐ０ is an integer from 0 to 2. ｐ１ is an integer from 0 to 10. ｐ２ is an integer from 0 to 10. ｐ３ is an integer from 0 to 10. ｐ０ +n ｐ１ +n ｐ２ +n ｐ３ is an integer between 1 and 30. ｐ１ If there are two or more R ｐ２ are the same or different. ｐ２ If there are two or more R ｐ３ are the same or different, and multiple R ｐ４ are the same or different. ｐ３ If there are two or more R ｐ５ are the same or different, and multiple R ｐ６ are the same or different. ＋ is a monovalent onium cation.

[0057] R ｐ１ Examples of the monovalent group containing a ring structure represented by the formula (I) include a monovalent group containing an alicyclic structure having 5 or more ring members, a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, a monovalent group containing an aromatic ring structure having 6 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 5 or more ring members.

[0058] Examples of the alicyclic structure having 5 or more ring members include: monocyclic cycloalkane structures such as a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure; monocyclic cycloalkene structures such as a cyclopentene structure, a cyclohexene structure, a cycloheptene structure, a cyclooctene structure, and a cyclodecene structure; polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure; and polycyclic cycloalkene structures such as a norbornene structure and a tricyclodecene structure.

[0059] Examples of the aliphatic heterocyclic structure having 5 or more ring members include: lactone structures such as a pentanolactone structure, a hexanolactone structure, and a norbornanelactone structure; sultone structures such as a pentanosultone structure, a hexanosultone structure, and a norbornanesultone structure; oxygen atom-containing heterocyclic structures such as an oxacyclopentane structure, an oxacycloheptane structure, and an oxanorbornane structure; nitrogen atom-containing heterocyclic structures such as an azacyclopentane structure, an azacyclohexane structure, and a diazabicyclooctane structure; and sulfur atom-containing heterocyclic structures such as a thiacyclopentane structure, a thiacyclohexane structure, and a thianorbornane structure.

[0060] Examples of the aromatic ring structure having six or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, and an anthracene structure.

[0061] Examples of the aromatic heterocyclic structure having 5 or more ring members include oxygen atom-containing heterocyclic structures such as a furan structure and a benzofuran structure, and nitrogen atom-containing heterocyclic structures such as a pyridine structure, a pyrimidine structure and an indole structure.

[0062] R ｐ１ The lower limit of the number of ring members of the ring structure may be 6, preferably 7, more preferably 8, even more preferably 9, and particularly preferably 10. On the other hand, the upper limit of the number of ring members is preferably 15, more preferably 14, even more preferably 13, and particularly preferably 12.

[0063] R ｐ１ Some or all of the hydrogen atoms in the ring structure may be substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, and oxo group (=O). Among these, hydroxy group and alkoxy group are preferred.

[0064] R ｐ１Among these, preferred are monovalent groups containing an alicyclic structure having 5 or more ring members and monovalent groups containing an aliphatic heterocyclic structure having 5 or more ring members, more preferred are monovalent groups containing an alicyclic structure having 6 or more ring members and monovalent groups containing an aliphatic heterocyclic structure having 6 or more ring members, even more preferred are monovalent groups containing an alicyclic structure having 9 or more ring members and monovalent groups containing an aliphatic heterocyclic structure having 9 or more ring members, and even more preferred are an adamantyl group, a hydroxyadamantyl group, a norbornane lactone-yl group, a norbornane sultone-yl group and a 5-oxo-4-oxatricyclo[4.3.1.13,8]undecan-yl group, with an adamantyl group being particularly preferred.

[0065] R ｐ２ The divalent organic group represented by the formula (2-1) is R ３ Among them, divalent organic groups having 1 to 40 carbon atoms and represented by R ｐ２ Examples of the divalent organic group represented by R include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, or a group formed by combining these groups. ｐ２ The divalent linking group represented by the formula (I) is preferably a carbonyloxy group, a sulfonyl group, an alkanediyl group, or a cycloalkanediyl group, more preferably a carbonyloxy group or a cycloalkanediyl group, still more preferably a carbonyloxy group or a norbornanediyl group, and particularly preferably a carbonyloxy group.

[0066] R ｐ３ and R ｐ４ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (R) include an alkyl group having 1 to 20 carbon atoms. ｐ３ and R ｐ４ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｐ３ and R ｐ４ As the alkyl group, a hydrogen atom, a fluorine atom and a fluorinated alkyl group are preferred, a fluorine atom and a perfluoroalkyl group are more preferred, and a fluorine atom and a trifluoromethyl group are even more preferred.

[0067] R ｐ５ and R ｐ６ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a fluorinated alkyl group having 1 to 20 carbon atoms. ｐ５ and R ｐ６ As the alkyl group, a fluorine atom and a fluorinated alkyl group are preferred, a fluorine atom and a perfluoroalkyl group are more preferred, a fluorine atom and a trifluoromethyl group are further preferred, and a fluorine atom is particularly preferred.

[0068] n ｐ０ is preferably 0 or 1.

[0069] n ｐ１ is preferably an integer of 0 to 5, more preferably an integer of 0 to 3, even more preferably an integer of 0 to 2, and particularly preferably 0 or 1.

[0070] n ｐ２ is more preferably an integer of 0 to 2, further preferably 0 or 1, and particularly preferably 0.

[0071] n ｐ３ is preferably an integer of 0 to 5, more preferably an integer of 1 to 4, even more preferably an integer of 1 to 3, and particularly preferably 1 or 2. ｐ３ By making n equal to or greater than 1, the strength of the acid generated from the compound of formula (p-1) can be increased, and as a result, the rectangularity of the resist pattern can be further improved. ｐ３ The upper limit of is preferably 4, more preferably 3, and even more preferably 2.

[0072] In the above formula (p-1), n ｐ０ +n ｐ１ +n ｐ２ +n ｐ３ is an integer between 1 and 30. ｐ０ +n ｐ１ +n ｐ２ +n ｐ３ The lower limit of n is preferably 2, more preferably 4. ｐ０ +n ｐ１ +n ｐ２ +n ｐ３ The upper limit of is preferably 20, more preferably 10.

[0073] R ４ Examples of the organic sulfonate anion moiety represented by the formula (p-1) above include structures represented by the following formulae (p-1-1) to (p-1-53):

[0074]

[0075]

[0076]

[0077]

[0078] As described above, R in the above formula (2-1) ３ is a divalent organic group having 1 to 40 carbon atoms represented by R in the above formula (2-2). ４ It corresponds to a structure in which one hydrogen atom or fluorine atom has been removed from a monovalent organic group having 1 to 40 carbon atoms, represented by the following formula:

[0079] Above Z １ ＋ Examples of the monovalent onium cation represented by the formula (X-1) include radiolytic onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, such as sulfonium cation, tetrahydrothiophenium cation, iodonium cation, phosphonium cation, diazonium cation, and pyridinium cation. Among these, sulfonium cation or iodonium cation is preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0080]

[0081] In the above formula (X-1), R ａ１ , R ａ２ and R ａ３are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or -OSO ２ -R Ｐ , -SO ２ -R Ｑ or -S-R Ｔ or a ring structure formed by combining two or more of these groups. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. Ｐ , R Ｑ and R Ｔ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R ａ１ ~R ａ３ and R Ｐ , R Ｑ and R Ｔ If there are multiple R ａ１ ~R ａ３ and R Ｐ , R Ｑ and R Ｔ may be the same or different.

[0082] In the above formula (X-2), R ｂ１ is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. ｋ is 0 or 1. ｋ When is 0, k4 is an integer from 0 to 4, and n ｋ When is 1, k4 is an integer from 0 to 7. ｂ１ If there are multiple R ｂ１ may be the same or different, and multiple Rｂ１ may represent a ring structure formed by combining with each other. ｂ２ is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. Ｃ is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R ｂ２ If there are multiple R ｂ２ may be the same or different, and multiple R ｂ２ may represent a ring structure formed by combining with each other, and q is an integer of 0 to 3. ＋ The ring structure containing the following may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton.

[0083] In the above formula (X-3), R ｃ１ , R ｃ２ and R ｃ３ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0084] In the above formula (X-4), R ｇ１ is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. ｋ２ is 0 or 1. ｋ２ When is 0, k10 is an integer from 0 to 4, and n ｋ２ When is 1, k10 is an integer from 0 to 7. ｇ１ If there are multiple R ｇ１ may be the same or different, and multiple R ｇ１ may represent a ring structure formed by combining with each other. ｇ２ and R ｇ３are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R ｇ２ and R ｇ３ If there are multiple R ｇ２ and R ｇ３ may be the same or different.

[0085] In the above formula (X-5), R ｄ１ and R ｄ２ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. R ｄ１ and R ｄ２ If there are multiple R ｄ１ and R ｄ２ may be the same or different.

[0086] In the above formula (X-6), R ｅ１ and R ｅ２ are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0087] Specific examples of the onium cation include, but are not limited to, structures of the following formulae (i-2-1) to (i-2-47).

[0088]

[0089]

[0090] Specific examples of the repeating unit (2-1) include repeating units represented by the following formulas (2-1-1) to (2-1-30).

[0091]

[0092]

[0093]

[0094]

[0095] (In the formula, R ａ has the same meaning as the above formula (2-1).

[0096] In the above formula (2-2), R ａ and L ３ are R in the above formula (2-1), ａ and L ２ The same groups as those shown below can be used.

[0097] In the above formula (2-2), Z ２ ＋ Examples of the monovalent group having a monovalent onium cation structure represented by the formula (2-1) include Z １ ＋ A group in which one hydrogen atom has been removed from a monovalent onium cation represented by the following formula can be suitably used.

[0098] R ４ The monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) is as already explained above.

[0099] Specific examples of the repeating unit (2-2) include repeating units represented by the following formulas (2-2-1) to (2-2-6).

[0100]

[0101]

[0102] In the formula, R ａ has the same meaning as the above formula (2-2).

[0103] When the polymer [A] contains a repeating unit (2), the lower limit of the content of the repeating unit (2) in all repeating units constituting the polymer [A] (total content when multiple types of repeating unit (2) are present) is preferably 1 mol %, more preferably 3 mol %, and even more preferably 5 mol %. The upper limit of the content is preferably 30 mol %, more preferably 25 mol %, and even more preferably 15 mol %. By setting the content of the repeating unit (2) within the above range, it is possible to impart high levels of pattern rectangularity and pattern defect suppression to the resist pattern.

[0104] (Repeating Unit (3)) The polymer (A) may contain a repeating unit (3) represented by the following formula (3).

[0105] (In formula (2), R ３１ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３１ is a single bond or a divalent linking group. ４１ is a group selected from the group consisting of groups represented by any one of the following formulas (3-1) to (3-8): (In formulas (3-1) to (3-3), (3-7), R ８ , R ９ , R １０ , R １２ and R １３ 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 １１ 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 １１ is a single bond, R １１ In formulas (3-1) to (3-8), R ７ is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３１ is the bond to the atoms that make up the atom.)

[0106] R ３１ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is１ A monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula can be preferably used. ３１ When R has a substituent, the substituent is R １ Examples of the substituent include the groups listed above.

[0107] L ３１ The divalent linking group represented by the formula (1) is １ Examples of the divalent linking group include the groups listed above as the divalent linking group represented by the formula: ３１ As the group, a single bond, -COO- ＊ ( ＊ is R ４１ is a bond to the group represented by the formula (I).) or a benzenediyl group is preferred.

[0108] In the above formulas (3-1) to (3-3) and (3-7), R ８ , R ９ , R １０ , R １１ , R １２ and R １３ (Hereinafter referred to as “R ８ ~R １３ ") is a monovalent organic group having 1 to 20 carbon atoms, such as R ２ The monovalent organic groups having 1 to 20 carbon atoms shown in the following formula can be suitably used.

[0109] R ８ ~R １３ are each independently preferably a hydrogen atom or a methyl group, and more preferably all are a hydrogen atom.

[0110] In the formula (3-2), 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 １ Preferably, Cy is a cycloalkane ring having 5 to 10 carbon atoms, more preferably a cyclopentane ring, a cyclohexane ring, or a cycloheptane ring.

[0111] In the above formulas (3-1) to (3-8), R ７ The divalent organic group having 1 to 20 carbon atoms represented by the above R８ ~R １３ 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:

[0112] R ７ 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.

[0113] Specific examples of the repeating unit (3) include repeating units represented by the following formulas (3-1) to (3-16).

[0114]

[0115] In the above formulas (3-1) to (3-16), R ３１ is the same as the above formula (3).

[0116] When the polymer [A] contains the repeating unit (3), the lower limit of the content of the repeating unit (3) relative to all repeating units constituting the polymer [A] (the total content when multiple types are included) is preferably 1 mol%, more preferably 20 mol%, and even more preferably 30 mol%. The upper limit of this content is preferably 90 mol%, more preferably 85 mol%, and even more preferably 80 mol%. By setting the content of the repeating unit (3) within the above range, solvent resistance and resist pattern rectangularity can be exhibited at high levels.

[0117] (Repeating Unit (4)) The polymer [A] may contain a repeating unit (4) having a hydroxy group (excluding the repeating units (1) to (3)). The hydroxy group also includes a structure in which the hydroxy group is protected with a protecting group. The protecting group is preferably a protecting group that can be deprotected by heating (e.g., 200°C) or a group that can form a protecting structure that can be deprotected by heating.

[0118] Examples of the protecting group or protecting structure for a hydroxy group include an acetal structure (protecting group: for example, an alkoxymethyl group), a cyclic acetal structure, a carbonate structure (protecting group: for example, an alkoxycarbonyl group), an ester structure (protecting group: for example, an acyl group), a trialkylsilyl group, and a benzyl group.

[0119] Specific examples of the repeating unit (4) include repeating units represented by the following formulas (4-1) to (4-12).

[0120]

[0121] In the above formulas (4-1) to (4-12), R ５１ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0122] R ５１ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is １ A monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula can be preferably used. ５１ When R has a substituent, the substituent is R １ Examples of the substituent include the groups listed above.

[0123] The lower limit of the weight-average molecular weight of the polymer (A) is preferably 5,000, more preferably 10,000, and even more preferably 15,000. The upper limit of the molecular weight is preferably 45,000, more preferably 40,000, and even more preferably 35,000. The method for measuring the weight-average molecular weight is as described in the Examples.

[0124] The lower limit of the content of the polymer [A] in the composition for forming a resist underlayer film is preferably 0.01 mass %, more preferably 0.05 mass %, still more preferably 0.10 mass %, and particularly preferably 0.20 mass %, based on the total mass of the polymer [A] and the solvent [B]. The upper limit of the content is preferably 5 mass %, more preferably 3 mass %, and still more preferably 2 mass %, based on the total mass of the polymer [A] and the solvent [B].

[0125] The lower limit of the content of the polymer (A) in the components other than the solvent (B) in the composition for forming a resist underlayer film is preferably 50% by mass, more preferably 60% by mass, and even more preferably 70% by mass, and the upper limit of the content may be 100% by mass, 98% by mass, or 95% by mass.

[0126] [Method for Synthesizing Polymer [A]] The polymer [A] can be synthesized by radical polymerization, ionic polymerization, etc. For example, when the polymer [A] is synthesized by radical polymerization, the polymer can be synthesized by polymerizing monomers that provide each repeating unit in an appropriate solvent using a radical polymerization initiator or the like.

[0127] 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), and dimethyl 2,2'-azobisisobutyrate (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.

[0128] 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.

[0129] 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.

[0130] <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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, 4-methyl-2-pentanol, and diacetone alcohol, and polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0135] Examples of the ketone solvent include chain ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and 2-heptanone, and cyclic ketone solvents such as cyclohexanone.

[0136] Examples of ether solvents include chain ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran, polyhydric alcohol ether solvents such as diethylene glycol dimethyl ether, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0137] 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.

[0138] The solvent (B) is preferably an ether-based solvent or an ester-based solvent, more preferably a monoalcohol-based solvent, a polyhydric alcohol partial ether-based solvent, or a polyhydric alcohol partial ether carboxylate-based solvent, and even more preferably propylene glycol monomethyl ether or propylene glycol monomethyl ether acetate.

[0139] The lower limit of the content of the solvent (B) in the composition for forming a resist underlayer film is preferably 90% by mass, more preferably 97% by mass, and still more preferably 98% by mass, and the upper limit of the content is preferably 99.99% by mass, and more preferably 99.95% by mass.

[0140] [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 crosslinker, an acid diffusion controller, a surfactant, an acid generator (in the form of a low molecule that is not bound to a polymer), 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) SA300". 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 may be used alone or in combination of two or more.

[0141] [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.

[0142] [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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] [Silicon-containing film forming step] In this step, which is carried out before the resist underlayer film forming composition coating step, a silicon-containing film is formed directly or indirectly on a substrate.

[0147] 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).

[0148] 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.

[0149] 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.

[0150] 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.

[0151] Examples of the case where a silicon-containing film is formed indirectly on a substrate include the case where a silicon-containing film is formed on a low dielectric insulating film formed on a substrate or on the organic underlayer film.

[0152] [Resist Underlayer Film Forming Composition Coating Step] In this step, a resist underlayer film forming composition is coated onto the silicon-containing film formed on the substrate. The method for coating the resist underlayer film forming composition is not particularly limited, and can be carried out 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].

[0153] When the composition for forming a resist underlayer film is applied directly to the substrate, the organic underlayer film forming step and the silicon-containing film forming step may be omitted.

[0154] 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).

[0155] 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.

[0156] The lower limit of the 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 6 nm. The average thickness is measured as described in the Examples.

[0157] [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.

[0158] Examples of the resist film-forming composition used in this step include positive or negative chemically amplified resist compositions that contain a radiation-sensitive acid generator, positive resist compositions that contain an alkali-soluble resin and a quinone diazide-based photosensitizer, negative resist compositions that contain an alkali-soluble resin and a crosslinking agent, and metal-containing resist film-forming compositions that contain a metal such as tin, zirconium, or hafnium.

[0159] The resist film preferably contains a metal. Such a resist film can be formed using a composition for forming a metal-containing resist film. The composition for forming a metal-containing resist film contains at least a metal-containing compound and a solvent. The lower limit of the content of the metal-containing compound in the components other than the solvent in the composition for forming a metal-containing resist film is preferably 50% by mass, more preferably 70% by mass, even more preferably 80% by mass, and particularly preferably 85% by mass. The upper limit of the content is, for example, 100% by mass or 95% by mass.

[0160] [Exposure Step] In this step, the resist film is exposed to radiation.

[0161] 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.

[0162] 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.

[0163] [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. Depending on the type of resist film-forming composition, the development may be performed by dissolving the resist film in a developer, by volatilizing the resist film by heating or reducing pressure, or by etching. This allows the formation of a resist pattern.

[0164] 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).

[0165] 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.

[0166] 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.

[0167] Examples of the etching method include dry etching, wet etching, etc. In the case of a metal-containing resist film-forming composition, dry etching using hydrogen bromide or the like is preferred.

[0168] In this step, after the development, washing and / or drying may be performed. Furthermore, etching may be performed using the resist pattern as a mask. Examples of the etching method include dry etching and wet etching.

[0169] The resist underlayer film-forming composition contains a polymer (A) and a solvent (B). As the resist underlayer film-forming composition, the resist underlayer film-forming composition used in the method for producing a semiconductor substrate can be suitably used.

[0170] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0171] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity index (PDI)] The Mw and Mn of the polymer were measured by gel permeation chromatography (detector: differential refractometer) using Tosoh Corporation's GPC columns (two "G2000HXL" columns and one "G3000HXL" column) under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40° C., with monodisperse polystyrene as the standard. The PDI was calculated from the determined Mw and Mn.

[0172] [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, using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"), and calculating the average of these film thicknesses.

[0173] <Synthesis of Polymer [A]> Each of the polymers [A] was synthesized according to the following procedure: Compounds (a-1) to (a-6), compounds (b-1) to (b-8), compounds (c-1) to (c-6), and compounds (d-1) to (d-5) were used as monomers represented by the following formulas in the synthesis of the polymer [A].

[0174]

[0175]

[0176]

[0177]

[0178]

[0179] Synthesis Example 1-1 Synthesis of Polymer (A-1) 15 g of cyclohexanone was placed in a reaction vessel and maintained at 80°C. A mixture of 0.47 g of compound (a-1), 17.4 g of compound (b-8), 7.37 g of compound (c-1), 2.09 g of dimethyl-2,2-azobis(2-methylpropionate), and 19.79 g of cyclohexanone 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 hexane and dried to obtain 13.3 g of polymer (A-1) as a white solid. The Mw of polymer (A-1) was 22,000, Mn was 6,700, and PDI was 3.3.

[0180] [Synthesis Examples 1-2 to 1-26] (Synthesis of Polymers (A-2) to (A-26) and (CA-1)) Polymers (A-2) to (A-26) and (CA-1) were obtained as products under the same reaction conditions as in Synthesis Example 1-1, except that the monomers and blending ratios (mol %) shown in Table 1 below were used. The Mw, Mn and PDI of the obtained polymers are shown in Table 1.

[0181]

[0182] <Preparation of Composition for Forming Resist Underlayer Film> [A] Polymer, comparative polymer, [B] solvent, [C] acid generator, and [D] crosslinking agent used in the preparation of the composition for forming the resist underlayer film are shown below.

[0183] [[A] Polymer] Polymers (A-1) to (A-26) synthesized above

[0184] [Comparative Polymer] Polymer (CA-1) synthesized above

[0185] [B] Solvents: B-1: Propylene glycol monomethyl ether acetate B-2: Propylene glycol monomethyl ether

[0186] [[C] Acid Generator] C-1: A compound represented by the following formula (C-1): C-2: A compound represented by the following formula (C-2): C-3: A compound represented by the following formula (C-3):

[0187]

[0188] [D] Crosslinking agent D-1: A compound represented by the following formula (D-1) D-2: A compound represented by the following formula (D-2)

[0189]

[0190] [Example 1-1] 99 parts by mass of (A-1) as a polymer [A] and 1 part by mass of (C-1) as an acid generator [C] were dissolved in 6,930 parts by mass of (B-1) as a solvent [B] and 2,970 parts by mass of (B-2). The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0191] Examples 1-2 to 1-32 and Comparative Example 1-1 Compositions (J-2) to (J-32) and (CJ-1) were prepared in the same manner as in Example 1-1, except that the types and amounts of each component were used as shown in Table 2. In Table 1, "-" indicates that the corresponding component was not used.

[0192]

[0193] Examples 2-1 to 1-32 and Comparative Example 2-1 Evaluation Using the compositions for forming resist underlayer films prepared above, the rectangularity and defect suppression ability of resist patterns were evaluated by the following methods. The evaluation results are shown in Table 3 below.

[0194] <Preparation of Resist Composition (R-1)> Resist composition (R-1) was prepared by mixing 100 parts by mass of resin (r-1), 20 parts by mass of acid generator (H-1), 50 mol % of acid diffusion controller (G-1) relative to the acid generator (H-1), and 7,700 parts by mass of propylene glycol monomethyl ether acetate and 3,300 parts by mass of propylene glycol monomethyl ether as solvents, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0195] Resin (r-1) was a polymer containing 50 mol % of repeating units derived from the following monomers (M-1) and (M-2), respectively, and had an Mw of 6,400 and an Mw / Mn of 1.50. The compounds shown below were used as the acid generator (H-1) and the acid diffusion controller (G-1).

[0196]

[0197] [Pattern Rectangularity] An organic underlayer film-forming material ("HM8006" manufactured by JSR Corporation) was applied to a 12-inch silicon wafer by a spin coating method 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 having an average thickness of 100 nm. A silicon-containing film-forming composition ("NFC SOG080" manufactured by JSR Corporation) 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 having an average thickness of 20 nm. The resist underlayer film-forming composition prepared above was applied to the silicon-containing film formed above, heated at 250°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film having 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 on-wafer line width of 26 nm). 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 tetramethylammonium hydroxide solution (20°C to 25°C), washed with water, and dried to obtain an evaluation substrate on which a 1:1 line and space resist pattern with a line width of 26 nm 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 pattern rectangularity was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, and as "B" (poor) when residue was present on the cross-section of the pattern.

[0198] [Pattern Defect Suppression] Fifteen images were obtained at 250,000 times magnification using a scanning electron microscope ("CG-4000" manufactured by Hitachi High-Technologies Corporation) for five locations in total, namely the center of an evaluation substrate on which the above-mentioned 1:1 line and space resist pattern with a line width of 26 nm had been formed and positions 5 cm apart horizontally and vertically from the center of the substrate. Images were evaluated as "A" (good) if no scum (residue) was present, and as "B" (poor) if scum was present.

[0199]

[0200] Examples 3-1 to 3-32 and Comparative Example 3-1 Evaluation Using the resist underlayer film-forming compositions prepared above, the rectangularity and defect suppression ability of the resist pattern were evaluated by the following methods. The evaluation results are shown in Table 4 below.

[0201] <Preparation of Resist Composition (R-2)> [Synthesis of Compound] 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 reaction was carried out for 2 hours. The precipitate that formed 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 a hydroxide oxide product (i-PrSnO) of the hydrolysis product of isopropyltin trichloride. （３／２-ｘ／２） (OH) ｘ (where 0<x<3 is the structural unit).

[0202] 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).

[0203] [Pattern Rectangularity] 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 25 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 (20-25°C) by a puddle method and then dried to obtain an evaluation substrate on which a 1:1 line and space resist pattern with a line width of 25 nm was formed. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-6300") was used to measure and observe the resist pattern of the evaluation substrate. The pattern rectangularity 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.

[0204] [Suppression of Pattern Defects] Images were obtained at a magnification of 250,000 times using a scanning electron microscope ("CG-4000" manufactured by Hitachi High-Technologies Corporation) for a total of five locations, namely the center of the evaluation substrate on which the above-mentioned 1:1 line and space resist pattern with a line width of 25 nm was formed and positions 5 cm apart horizontally and vertically from the center of the substrate. Images were evaluated as "A" (good) if no scum (residue) was present, and as "B" (poor) if scum was present.

[0205]

[0206] As can be seen from the results in Tables 3 and 4, the resist underlayer films formed from the compositions for forming resist underlayer films of Examples were superior in pattern rectangularity and pattern defect suppression ability compared to the resist underlayer films formed from the compositions for forming resist underlayer films of Comparative Examples.

[0207] According to the method for producing a semiconductor substrate of the present invention, a composition for forming a resist underlayer film is used, which is capable of forming a resist underlayer film that can exhibit excellent pattern rectangularity and pattern defect suppression when forming a resist pattern, so that semiconductor substrates can be produced efficiently. The composition for forming a resist underlayer film of the present invention can form a resist underlayer film that can exhibit excellent pattern rectangularity and pattern defect suppression when forming a resist pattern. Therefore, these compositions can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. 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 and a solvent, and the polymer contains a repeating unit (1) represented by the following formula (1): (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a single bond or a divalent linking group. ２ is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium.

2. The method for producing a semiconductor substrate according to claim 1, wherein the polymer further comprises a repeating unit (2) having an organic sulfonate anion moiety and an onium cation moiety.

3. The method for producing a semiconductor substrate according to claim 2, wherein the repeating unit (2) is a repeating unit represented by the following formula (2-1) or (2-2): (In formula (2-1), R ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２ is a divalent linking group. ３ is a single bond or a divalent organic group having 1 to 40 carbon atoms. １ ＋ is a monovalent onium cation. ａ and L ３ are R in the above formula (2-1), ａ and L ２ It is synonymous with Z. ２ ＋ is a monovalent group having a monovalent onium cation structure. ４ is a monovalent organic group having 1 to 40 carbon atoms.

4. The method for producing a semiconductor substrate according to any one of claims 1 to 3, wherein the resist film contains a metal.

5. The method for producing a semiconductor substrate according to claim 4, wherein the resist film is formed from a composition for forming a metal-containing resist film, the composition for forming a metal-containing resist film contains a metal-containing compound and a solvent, and the content of the metal-containing compound in the components other than the solvent in the composition for forming a metal-containing resist film is 50 mass % or more.

6. The method for producing a semiconductor substrate according to any one of claims 1 to 3, wherein the content of the repeating unit (1) in all repeating units constituting the polymer is 1 mol % or more and 90 mol % or less.

7. The method for producing a semiconductor substrate according to claim 2 or 3, wherein the content of the repeating unit (2) in all repeating units constituting the polymer is 1 mol % or more and 30 mol % or less.

8. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 3, wherein the radiation is an electron beam or extreme ultraviolet light.

9. A composition for forming a resist underlayer film, comprising: a polymer; and a solvent, wherein the polymer contains a repeating unit (1) represented by the following formula (1): (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a single bond or a divalent linking group. ２ is a monovalent group containing an atom selected from the group consisting of silicon, zinc, aluminum, germanium, tin, titanium, zirconium, and hafnium.

10. The composition for forming a resist underlayer film according to claim 9, wherein the polymer further comprises a repeating unit (2) having an organic sulfonate anion moiety and an onium cation moiety.

11. The composition for forming a resist underlayer film according to claim 10, wherein the repeating unit (2) is a repeating unit represented by the following formula (2-1) or (2-2): (In formula (2-1), R ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ２ is a divalent linking group. ３ is a single bond or a divalent organic group having 1 to 40 carbon atoms. １ ＋ is a monovalent onium cation. ａ and L ３ are R in the above formula (2-1), ａ and L ２ It is synonymous with Z. ２ ＋ is a monovalent group having a monovalent onium cation structure. ４ is a monovalent organic group having 1 to 40 carbon atoms.

12. The composition for forming a resist underlayer film according to any one of claims 9 to 11, wherein the content of the repeating unit (1) in all repeating units constituting the polymer is 1 mol % or more and 90 mol % or less.

13. A composition for forming a resist underlayer film according to claim 10 or 11, wherein the content of the repeating unit (2) in all repeating units constituting the polymer is 1 mol % or more and 30 mol % or less.

14. R ２ The composition for forming a resist underlayer film according to any one of claims 9 to 11, wherein is a group represented by the following formula (a): (In formula (a), M is a silicon atom, zinc atom, aluminum atom, germanium atom, tin atom, titanium atom, zirconium atom, or hafnium atom. R ２ａ is a monovalent organic group having 1 to 20 carbon atoms. ２ａ If there are multiple R ２ａ are each independently a monovalent organic group having 1 to 20 carbon atoms, or a plurality of R ２ａ Two of them are combined with each other to form a ring structure together with the M to which they are attached. k is the value obtained by subtracting 1 from the valence value of the atom represented by M. * is L １ It is a bond with 15. The composition for forming a resist underlayer film according to claim 14, wherein M is a silicon atom or a tin atom.

16. R ２ａ The composition for forming a resist underlayer film according to claim 14, wherein is a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group.

17. R ２ａ The composition for forming a resist underlayer film according to claim 14, wherein is a substituted or unsubstituted alkyl group.

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