Method for producing semiconductor substrate, and resist underlayer film-forming composition

Abstract

Provided are: a resist underlayer film-forming composition that is capable of forming a resist underlayer film that can impart excellent pattern rectangularity to a resist pattern; and a method for producing a semiconductor substrate. The method for producing a semiconductor substrate comprises: a step for directly or indirectly coating a substrate with a resist underlayer film-forming composition; a step for forming a resist film on the resist underlayer film formed by the aforementioned step for coating a resist underlayer film-forming composition; a step for exposing the resist film to radiation; and a step for developing at least the exposed resist film. The resist underlayer film-forming composition contains a polymer and a solvent. The polymer contains a repeating unit (1) having an organosulfonate anion moiety and an onium cation moiety, a repeating unit (2) represented by formula (2), and a repeating unit (3) represented by formula (3). (In formula (2), R4 is a group selected from the group consisting of groups represented by any of formulas (2-1) to (2-8).) (In formula (3), R6 is a group that contains a substructure represented by formula (3-1) or (3-2).) (In formulas (3-1) and (3-2), X1 and X2 are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. A formula in which a solid line and a broken line are combined indicates a single bond or a double bond each independently.)

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 there has been a trend toward shorter wavelength exposure light, 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 for such EUV exposure (see International Publication No. 2013 / 141015).

[0004] International Publication No. 2013 / 141015

[0005] As resist patterns formed by exposure to extreme ultraviolet light and development become increasingly finer, there is a demand for pattern rectangularity that suppresses pattern footing at the bottom of the resist film and ensures 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 that is capable of forming a resist underlayer film that can impart excellent pattern rectangularity to a resist pattern, and a method for producing a semiconductor substrate.

[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 in 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 [C]”), and the polymer contains: a repeating unit (1) having an organic sulfonate anion moiety and an onium cation moiety; a repeating unit (2) represented by the following formula (2); and a repeating unit (3) represented by the following formula (3). (In formula (2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ is a single bond or a divalent linking group. ４ 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 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 (2-1) to (2-8), R ７ is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３ is the bond to the atoms that make up the atom.) (In formula (3), R ５ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４is a single bond or a divalent linking group. ６ is a group containing a partial structure represented by the following formula (3-1) or (3-2): (In formulas (3-1) and (3-2), X １ and X ２ are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. １ Between C on the left side of the formula and X ２ and C on the right side of the formula, each independently represents a single bond or a double bond, except when formula (3-2) corresponds to formula (3-1).

[0008] 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 comprises: a repeating unit (1) having an organic sulfonate anion moiety and an onium cation moiety; a repeating unit (2) represented by the following formula (2); and a repeating unit (3) represented by the following formula (3): (In formula (2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ is a single bond or a divalent linking group. ４ 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 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 (2-1) to (2-8), R ７is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３ is the bond to the atoms that make up the atom.) (In formula (3), R ５ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４ is a single bond or a divalent linking group. ６ is a group containing a partial structure represented by the following formula (3-1) or (3-2): (In formulas (3-1) and (3-2), X １ and X ２ are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. １ Between C on the left side of the formula and X ２ and C on the right side of the formula, each independently represents a single bond or a double bond, except when formula (3-2) corresponds to formula (3-1).

[0009] In this specification, the term "number of ring members" refers to the number of atoms forming a ring, whether it is a monocyclic or polycyclic ring. For example, the number of ring members is 5 for tetrahydrofuran, 6 for benzene, 10 for adamantane, 10 for quinoline, 12 for biphenyl, and 13 for fluorene.

[0010] According to the method for producing a semiconductor substrate, a composition for forming a resist underlayer film is used, which is capable of forming a resist underlayer film that can impart excellent pattern rectangularity to a resist pattern, thereby enabling efficient production of a semiconductor substrate. The composition for forming a resist underlayer film can form a resist underlayer film that can impart excellent pattern rectangularity to 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.

[0011] 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.

[0012] <<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").

[0013] 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 that can impart excellent pattern rectangularity to a resist pattern can be formed, and therefore a semiconductor substrate having a good pattern shape can be produced.

[0014] 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.

[0015] Hereinafter, a description will be given of the composition for forming a resist underlayer film used in the method for producing a semiconductor substrate, and each step in the case where the method includes an optional organic underlayer film forming step.

[0016] <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 [C]. 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 [C], the composition for forming a resist underlayer film can form a resist underlayer film that can impart excellent pattern rectangularity to the resist pattern.

[0017] <Polymer [A]> The polymer [A] contains repeating units (1), (2), and (3). The polymer [A] may contain other repeating units in addition to these repeating units. The polymer [A] may contain one or more types of each of the repeating units (1), (2), and (3). The composition can contain one or more types of polymer [A]. The polymer [A] is preferably an acrylic polymer.

[0018] (Repeating Unit (1)) The repeating unit (1) has 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, and 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.

[0019] When the polymer (A) is an acrylic polymer, the repeating unit (1) is preferably a repeating unit represented by the following formula (1-1) or (1-2) (hereinafter, also referred to as “repeating unit (1-1)”): (In formula (1-1), R ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a divalent linking group. １ is a single bond or a divalent organic group having 1 to 40 carbon atoms. １ ＋ is a monovalent onium cation. ａ and L ２ are R in the above formula (1-1), ａ and L １ It is synonymous with Z. ２ ＋ is a monovalent group having a monovalent onium cation structure. ２is a monovalent organic group having 1 to 40 carbon atoms.

[0020] In the repeating unit (1-1), the organic sulfonate anion moiety (—R １ 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 (1-2), 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 ２ SO ３ － ) is contained as its counter ion.

[0021] In this specification, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a linear structure, and includes both linear hydrocarbon groups 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, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not have to be composed only 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 have to be composed only of an aromatic ring structure and may contain an alicyclic structure or a linear structure as part of it).

[0022] R in the above formulas (1-1) and (1-2) ａ 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.

[0023] 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, sec-butyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0024] 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.

[0025] 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.

[0026] 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, or a butyryl group, a cyano group, a nitro group, and a hydroxy group.

[0027] Among them, R ａ In terms of copolymerizability of the monomer that gives the repeating unit (1), a hydrogen atom or a methyl group is preferred.

[0028] In the above formulas (1-1) and (1-2), L １ and L ２ 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 combining these can be suitably used.

[0029] L １ and L ２ 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: １ and L ２ Preferably, the group contains a divalent aromatic ring, and more preferably contains a benzenediyl group or a naphthalenediyl group.

[0030] R in the above formula (1-1) １ The divalent organic group having 1 to 40 carbon atoms represented by the formula (1-2) is ２ Therefore, first, R in the above formula (1-2) is ２ In this specification, an "organic group" is a group having at least one carbon atom.

[0031] R in the above formula (1-2) ２ Examples of the monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 40 carbon atoms, a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the carbon chain terminal, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing substituent, and a combination thereof.

[0032] The monovalent hydrocarbon group having 1 to 40 carbon atoms includes the above-mentioned R ａ A group in which the number of carbon atoms of a monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the following formula (I) is extended to 40, can be suitably used.

[0033] 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.

[0034] 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.

[0035] Examples of the monovalent heteroatom-containing substituent include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0036] The above R ２ The organic sulfonate anion moiety containing the following is preferably represented by the following formula (p-1): ３ － ) is R ２ 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 Rｐ６ are the same or different. ＋ is a monovalent onium cation.

[0037] 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 6 or more ring members.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Examples of the aromatic heterocyclic structure having 6 or more ring members include oxygen atom-containing heterocyclic structures such as a furan structure, a pyran structure, and a benzopyran structure, and nitrogen atom-containing heterocyclic structures such as a pyridine structure, a pyrimidine structure, and an indole structure.

[0042] 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.

[0043] 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.

[0044] R ｐ１ Among 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, 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]undecane-yl group, and particularly preferred is an adamantyl group.

[0045] R ｐ２ The divalent organic group represented by the formula (1-1) is R １ Among them, divalent organic groups having 1 to 40 carbon atoms and represented by R ｐ２Examples 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.

[0046] 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.

[0047] 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.

[0048] n ｐ０ is preferably 0 or 1.

[0049] 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.

[0050] nｐ２ is more preferably an integer of 0 to 2, further preferably 0 or 1, and particularly preferably 0.

[0051] 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.

[0052] 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.

[0053] R represented by the above formula (p-1) １ Examples of the organic sulfonate anion moiety containing the formula include structures represented by the following formulae (p-1-1) to (p-1-53).

[0054]

[0055]

[0056]

[0057]

[0058] As described above, R in the above formula (1-1) １ is a divalent organic group having 1 to 40 carbon atoms represented by R ２It 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:

[0059] 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).

[0060]

[0061] In the above formula (X-1), R ａ１ , R ａ２ and R ａ３ are 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. R 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 ａ３and 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.

[0062] 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 R ｂ１ 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.

[0063] 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.

[0064] In the above formula (X-4), R ｇ１is 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 ｇ３ are 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.

[0065] 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.

[0066] 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.

[0067] Specific examples of the onium cation include, but are not limited to, structures of the following formulae (i-2-1) to (i-2-47).

[0068]

[0069]

[0070] Specific examples of the repeating unit (1-1) include repeating units represented by the following formulas (1-1-1) to (1-1-22).

[0071]

[0072]

[0073]

[0074] (In the formula, R ａ has the same meaning as the above formula (1-1).

[0075] In the above formula (1-2), R ａ and L ２ are R in the above formula (1-1), ａ and L １ The same groups as those shown below can be used.

[0076] In the above formula (1-2), Z ２ ＋ As the monovalent group having a monovalent onium cation structure represented by the formula (1-1), 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.

[0077] R ２The monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) is as already explained above.

[0078] Specific examples of the repeating unit (1-2) include repeating units represented by the following formulas (1-2-1) to (1-2-6).

[0079]

[0080]

[0081] In the formula, R ａ has the same meaning as the above formula (1-2).

[0082] The lower limit of the content of the repeating unit (1) in all repeating units constituting the polymer (A) (total when multiple types of repeating unit (1) are present) is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol%. The upper limit of the content is preferably 50 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By ensuring that the content of the repeating unit (1) falls within the above range, it is possible to impart a high level of pattern rectangularity to the resist pattern.

[0083] (Repeating Unit (2)) The repeating unit (2) is a repeating unit represented by the following formula (2).

[0084] (In formula (2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ is a single bond or a divalent linking group. ４ 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 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 １１is 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 (2-1) to (2-8), R ７ is a divalent organic group having 1 to 20 carbon atoms or a single bond. ３ is the bond to the atoms that make up the atom.)

[0085] R ３ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1-1) is ａ The groups listed as examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the above R ３ When has a substituent, the substituent is R ａ Examples of the substituent include the groups listed above.

[0086] L ３ Examples of the divalent linking group represented by the formula (1-1) include L １ Examples of the divalent linking group include the groups listed above as the divalent linking group represented by the formula: ３ Examples of the group include a single bond and —COO—. ＊ ( ＊ is R ４ is a bond to the group represented by the formula (I).) or a benzenediyl group is preferred.

[0087] In the above formulas (2-1) to (2-3) and (2-7), 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 Among the monovalent organic groups having 1 to 40 carbon atoms represented by the following formula, groups having 1 to 20 carbon atoms can be suitably used.

[0088] R ８ ~R １３are each independently preferably a hydrogen atom or a methyl group, and more preferably all are a hydrogen atom.

[0089] 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 ａ Preferably, Cy is a cycloalkane ring having 5 to 10 carbon atoms, more preferably a cyclopentane ring, a cyclohexane ring, or a cycloheptane ring.

[0090] In the above formulas (2-1) to (2-8), R ７ The divalent organic group having 1 to 20 carbon atoms represented by the above R ８ ~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:

[0091] 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.

[0092] Specific examples of the repeating unit (2) include repeating units represented by the following formulas (2-1) to (2-16).

[0093]

[0094] In the above formulas (2-1) to (2-16), R ３ is synonymous with the above formula (2).

[0095] The lower limit of the content of repeating unit (2) in all repeating units constituting the polymer [A] (the total content when multiple types are included) is preferably 1 mol%, more preferably 15 mol%, even more preferably 30 mol%, and particularly preferably 40 mol%. The upper limit of this content is preferably 80 mol%, more preferably 70 mol%, even more preferably 60 mol%, and particularly preferably 55 mol%. By keeping the content of repeating unit (3) within the above range, solvent resistance and resist pattern rectangularity can be exhibited at high levels.

[0096] (Repeating Unit (3)) The repeating unit (3) is a repeating unit represented by the following formula (3).

[0097] (In formula (3), R ５ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４ is a single bond or a divalent linking group. ６ is a group containing a partial structure represented by the following formula (3-1) or (3-2) (hereinafter, also referred to as "partial structure (3-1)" etc.). (In formulas (3-1) and (3-2), X １ and X ２ are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. １ Between C on the left side of the formula and X ２ and C on the right side of the formula, each independently represents a single bond or a double bond, except when formula (3-2) corresponds to formula (3-1).

[0098] R ５ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1-1) is ａ The groups listed as examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the above R ３ When has a substituent, the substituent is R ａ Examples of the substituent include the groups listed above.

[0099] L ４ Examples of the divalent linking group represented by the formula (1-1) include L １ Examples of the divalent linking group include the groups listed above as the divalent linking group represented by the formula: ４ Examples of the group include a single bond and —COO—. ＊ ( ＊ is R ４ is a bond to the group represented by the formula (I).) or a benzenediyl group is preferred.

[0100] The partial structure (3-1) and the partial structure (3-2) are X in the above formulas (3-1) and (3-2). １ , X ２ and represents only a partial structure consisting of two carbon atoms. １ , X ２ and the two carbon atoms are each bonded to one or more other atoms depending on the valence of each atom.

[0101] The partial structure (3-1) and the partial structure (3-2) may each constitute a part of a chain structure or a part of a cyclic structure. When the partial structure (3-1) or the partial structure (3-2) constitutes a part of a cyclic structure, the carbon-X １ The bond forms part of one ring structure, and the carbon-X ２ The bond may also be part of another ring structure.

[0102] In the above formulas (3-1) and (3-2), carbon-carbon and carbon-X １ Between or carbon-X ２ When the following formula between represents a double bond, this double bond also includes a conjugated bond when the cyclic structure exhibits aromaticity.

[0103] Specific examples of the partial structure (3-1) and the partial structure (3-2) include structures represented by the following formulas (3-1-1) to (3-1-5) or (3-2-1).

[0104]

[0105] The partial structure is preferably represented by the above formula (3-1-1), (3-1-2), (3-1-3) or (3-2-1).

[0106] In the partial structure (3-1), X １ and X ２ are preferably each independently contained as a part of a hydroxy group, a thiol group, an amino group, or a group obtained by protecting these with a protecting group. The protecting group is preferably a protecting group that is deprotected by heating (e.g., 200°C) or a group that can form a protected structure that is deprotected by heating.

[0107] Examples of the protecting group or protecting structure for the hydroxy group include an acetal structure (wherein the protecting group is, for example, an alkoxymethyl group), a cyclic acetal structure (X １ and X ２ constitute a hydroxy group), a carbonate structure (where the protecting group is, for example, an alkoxycarbonyl group), an ester structure (where the protecting group is, for example, an acyl group), a trialkylsilyl group, a benzyl group, etc.

[0108] Examples of the protecting group or protecting structure for the thiol group include a thioacetal structure (wherein the protecting group is, for example, an alkylthiomethyl group), a cyclic thioacetal structure (X １ and X ２ and a protective structure in which each of the groups constitutes a thiol group.

[0109] Examples of the protecting group or protecting structure for the amino group include a carbamate structure (protecting group: for example, an alkoxycarbonyl group, etc.) and an amide structure (protecting group: for example, an acyl group, etc.).

[0110] R ６ In the formula (2-1) to (2-8), R ７ Among these, a hydrocarbon group having 1 to 10 carbon atoms and a group formed by combining such a hydrocarbon group having 1 to 10 carbon atoms with -O- are preferred, a chain hydrocarbon group having 1 to 5 carbon atoms and a group formed by combining such a chain hydrocarbon group having 1 to 5 carbon atoms with -O- are more preferred, and a methylene group, an ethanediyl group, a group formed by combining a methylene group with -O-, and a group formed by combining an ethanediyl group with -O- are even more preferred.

[0111] Specific examples of the repeating unit (3) include repeating units represented by the following formulas (3-1) to (3-24).

[0112]

[0113]

[0114] In the above formulas (3-1) to (3-24), R ５ is synonymous with the above formula (2).

[0115] The lower limit of the content of repeating unit (3) in 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 80 mol%, more preferably 70 mol%, and even more preferably 50 mol%. By keeping the content of repeating unit (3) within the above range, high levels of solvent resistance and resist pattern rectangularity can be achieved.

[0116] The lower limit of the weight average molecular weight (Mw) 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 20000, more preferably 15000, even more preferably 12000, and particularly preferably 10000. The method for measuring the weight average molecular weight is as described in the Examples.

[0117] The polydispersity (Mw / Mn) of the polymer (A) is preferably 1 or more and 5 or less, more preferably 1 or more and 3 or less, and even more preferably 1 or more and 2 or less.

[0118] 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 %, even more preferably 0.10 mass %, and particularly preferably 0.12 mass %, based on the total mass of the polymer [A] and the solvent [C]. The upper limit of the content is preferably 3 mass %, more preferably 2 mass %, even more preferably 1 mass %, and particularly preferably 0.8 mass %, based on the total mass of the polymer [A] and the solvent [C].

[0119] The lower limit of the content of the polymer (A) in the components other than the solvent (C) 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.

[0120] [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.

[0121] 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; 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.

[0122] As the solvent used in the polymerization, the solvent [C] described below can be suitably used. These solvents used in the polymerization may be used alone or in combination of two or more kinds.

[0123] 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.

[0124] <Solvent (C)> The solvent (C) is not particularly limited as long as it can dissolve or disperse the polymer (A) and any optional components contained as needed.

[0125] Examples of the solvent (C) include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, etc. The solvent (C) can be used alone or in combination of two or more.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] Examples of the ether solvent 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.

[0131] Examples of nitrogen-containing solvents include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0132] The solvent (C) is preferably an alcohol solvent, a ketone solvent, an ether solvent, or an ester solvent, more preferably a monoalcohol solvent, a cyclic ketone solvent, a polyhydric alcohol partial ether solvent, a polyhydric alcohol partial ether carboxylate solvent, or a lactate ester solvent, and even more preferably diacetone alcohol, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or ethyl lactate.

[0133] The lower limit of the content of the solvent (C) 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.

[0134] [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 crosslinkers, acid diffusion controllers, polymers different from the polymer [A], polysiloxanes, polycarbosilanes, surfactants, acid generators (in the form of low molecules that are not bonded to the polymer), and the like. The optional components may be used alone or in combination of two or more. Examples of polymers different from the polymer [A] include polymers having repeating units represented by the following formulas (F-1) to (F-7). The Mw of the polymer is not particularly limited and is typically 5,000 to 20,000.

[0135]

[0136] [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 [C], 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.

[0137] [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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] [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 [C].

[0142] When the composition for forming a resist underlayer film is applied directly to the substrate, the organic underlayer film forming step may be omitted.

[0143] 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 (C).

[0144] 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.

[0145] 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.

[0146] [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.

[0147] 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.

[0148] 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.

[0149] (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.

[0150] (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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] (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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] The metal atom represented by M is preferably a metal atom of Group 14, more preferably tin.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] Examples of the acyloxy group represented by Y include a formyl group, an acetoxy group, an ethyryloxy 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.

[0165] 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.

[0166] 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.

[0167] L Ａ The ligand represented by the formula (I) includes a monodentate ligand and a polydentate ligand.

[0168] Examples of the monodentate ligand include a hydroxo ligand, a nitro ligand, and ammonia.

[0169] 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.

[0170] 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.

[0171] L Ａ The monovalent organic group represented by the formula (1-2) is R ２ Among the monovalent organic groups having 1 to 40 carbon atoms represented by the following formula, groups having 1 to 20 carbon atoms can be suitably used.

[0172] 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.

[0173] As a1, 1 and 2 are preferred, and 1 is more preferred.

[0174] 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.

[0175] The metal compound precursor (1) is preferably a metal halide compound, more preferably isopropyltin trichloride or benzyltin trichloride.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] (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 (C) in the composition for forming a resist underlayer film.

[0181] As the solvent (F), an ether solvent is preferred, and propylene glycol monoethyl ether is more preferred.

[0182] (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).

[0183] (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).

[0184] (Surfactant) The surfactant is a component that acts to improve the coatability, striations, etc. Examples of the surfactant 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 commercial surfactants such as KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 85 (Shin-Etsu Chemical Co., Ltd.). 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.

[0185] (Method for preparing a composition for forming a metal-containing resist film) The composition for forming a metal-containing resist film can be prepared, for example, by mixing the metal-containing compound (A), the solvent (F), and other optional components in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter with a pore size of 0.4 μm or less. The content of the metal-containing compound (A) in the components other than the solvent (F) in the composition for forming a metal-containing resist film is preferably 50 mass% or more. The lower limit of the content of the metal-containing compound (A) is more preferably 60 mass%, and even more preferably 70 mass%. On the other hand, the upper limit of the content is preferably 100 mass%, but may be 98 mass% or 95 mass%.

[0186] <Method for forming a coated film using a composition for forming a metal-containing resist film> The method for applying the composition for forming a metal-containing resist film is not particularly limited, and examples thereof include a rotary coating method.

[0187] To explain this step in more detail, for example, a composition for forming a metal-containing resist film is applied so that the metal-containing resist film to be formed has a predetermined thickness, and then the composition is pre-baked (hereinafter also referred to as "PB") to volatilize the solvent in the coated film, thereby forming a resist film.

[0188] The PB temperature and PB time can be appropriately determined depending on the type of metal-containing 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.

[0189] [Exposure Step] In this step, the resist film is exposed to radiation.

[0190] 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.

[0191] 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.

[0192] [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.

[0193] 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).

[0194] The basic liquid for alkaline development is not particularly limited, and known basic liquids can be used. Examples of basic liquids for alkaline development include aqueous alkaline solutions containing at least one alkaline compound dissolved therein, 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, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0195] Examples of organic solvent developers for use in organic solvent development include those exemplified above as the solvent [C]. Preferred organic solvent developers are ester-based solvents, ether-based solvents, alcohol-based solvents, ketone-based solvents, and / or hydrocarbon-based solvents, more preferably ketone-based solvents, and particularly preferably 2-heptanone.

[0196] 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.

[0197] The resist underlayer film-forming composition contains a polymer (A) and a solvent (C). 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.

[0198] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0199] [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.

[0200] [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.

[0201] <Synthesis of Polymer [A]> Each of the polymers [A] was synthesized according to the following procedure: The following compounds (a-1) to (a-4), compounds (b-1) to (b-15), and compounds (c-1) to (c-24) were used as monomers in the synthesis of the polymer [A].

[0202]

[0203]

[0204]

[0205]

[0206]

[0207] Synthesis Example 1-1 Synthesis of Polymer (A-1) 17 g of dimethylacetamide was placed in a reaction vessel and maintained at 80°C. A mixed solution of 3.00 g of compound (a-1), 6.35 g of compound (b-1), 5.20 g of compound (c-1), 2.62 g of dimethyl-2,2-azobis(2-methylpropionate), and 34.00 g of dimethylacetamide 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 10-fold amount of methanol and dried to obtain 13.6 g of polymer (A-1) as a white solid. The Mw of polymer (A-1) was 5,500, Mn was 3,200, and PDI was 1.7.

[0208] [Synthesis Examples 1-2 to 1-50] (Synthesis of Polymers (A-2) to (A-50)) Polymers (A-2) to (A-50) were obtained as products under the same reaction conditions as in Synthesis Example A-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.

[0209]

[0210] <Synthesis of Polymer [B]> A polymer represented by the following formula (B-1) (hereinafter also referred to as "polymer (B-1)") was synthesized according to the procedure shown below. In the following formula, the number attached to the repeating unit indicates the content (mol %) of that repeating unit.

[0211]

[0212] Synthesis Example 2-1 (Synthesis of Polymer (B-1)) 63 g of acrylic acid, 36 g of 2-ethylhexyl acrylate, and 21.2 g of dimethyl 2,2'-azobis(2-methylpropionate) were added to prepare a monomer solution. 300 g of methyl isobutyl ketone was placed in a reaction vessel under a nitrogen atmosphere, and the mixture was heated to 80°C. While stirring, the monomer solution was added dropwise over 3 hours. The start of the dropwise addition marked the start of the polymerization reaction. After the polymerization reaction was carried out for 6 hours, the mixture was cooled to 30°C or below. 300 g of propylene glycol monomethyl ether was added to the reaction solution, and the methyl isobutyl ketone was removed by concentration under reduced pressure, yielding a propylene glycol monomethyl ether solution of polymer (B-1). The Mw of polymer (B-1) was 6,500.

[0213] <Preparation of Composition> The polymer [A], polymer [B], solvent [C] and optional components used in the preparation of the composition are shown below.

[0214] [[A] Polymer] Polymers (A-1) to (A-50) synthesized above

[0215] [[B] Polymer] Polymer (B-1) synthesized above

[0216] [[C] Solvent] C-1: Propylene glycol monomethyl ether acetate C-2: Propylene glycol monomethyl ether C-3: Ethyl lactate C-4: Diacetone alcohol C-5: Cyclohexanone

[0217] [Optional Components] D-1: Compound represented by the following formula (D-1) D-2: Compound represented by the following formula (D-2) E-1: Compound represented by the following formula (E-1) F-1: Polymer having a repeating unit represented by the following formula (F-1) (Mw is 10,000) F-2: Polymer having a repeating unit represented by the following formula (F-2) (Mw is 11,000) F-3: Polymer having a repeating unit represented by the following formula (F-3) (Mw is 11,000) F-4: Polymer having a repeating unit represented by the following formula (F-4) (Mw is 10,000)

[0218]

[0219] [Example 1] 50 parts by mass of (A-1) as a polymer [A], 80,000 parts by mass of (C-1) as a solvent [C], and 2,000 parts by mass of (C-5) were dissolved in each other. 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).

[0220] Examples 2 to 54 and Comparative Example 1 Compositions (J-2) to (J-54) and (CJ-1) were prepared in the same manner as in Example 1, except that the types and amounts of each component were used as shown in Table 2. In Table 1, a "-" in the "A, B, optional components" column indicates that the corresponding component was not used.

[0221]

[0222] <Evaluation> Using the composition for forming a resist underlayer film prepared above, the rectangularity of the resist pattern was evaluated by the following method. The evaluation results are shown in Table 3 below.

[0223] <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 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.

[0224] 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).

[0225]

[0226] [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 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 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 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 solution of tetramethylammonium hydroxide (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 there was a footing on the cross section of the pattern.

[0227]

[0228] <Evaluation> Using the composition for forming a resist underlayer film prepared above, the rectangularity of the resist pattern was evaluated by the following method. The evaluation results are shown in Table 4 below.

[0229] <Preparation of Resist Composition (R-2)> [Synthesis of Compound] Compound (S-1) used in the preparation of 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).

[0230] 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).

[0231] [Pattern Rectangularity (EUV Exposure)] An organic underlayer film-forming material ("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 by a puddle method using 2-heptanone (20-25°C) 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.

[0232]

[0233] 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 the Examples were superior in pattern rectangularity compared to the resist underlayer films formed from the compositions for forming resist underlayer films of the Comparative Examples.

[0234] 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 impart excellent pattern rectangularity to a resist pattern, thereby enabling efficient production of a semiconductor substrate. The composition for forming a resist underlayer film of the present invention allows the formation of a resist underlayer film that can impart excellent pattern rectangularity to 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) having an organic sulfonate anion portion and an onium cation portion, a repeating unit (2) represented by the following formula (2), and a repeating unit (3) represented by the following formula (3): (In formula (2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ R is a single bond or a divalent linking group. ４ 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 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 (2-1) to (2-8), R ７ is a divalent organic group having 1 to 20 carbon atoms or a single bond. * is L ３ is a bond to the atoms that make up the molecule.) (In formula (3), R ５ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４ R is a single bond or a divalent linking group. ６ is a group containing a partial structure represented by the following formula (3-1) or (3-2): (In the formulas (3-1) and (3-2), X １ and X ２ are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. １ Between C on the left side of the formula and X ２ and C on the right side of the formula each independently represent a single bond or a double bond, except when formula (3-2) corresponds to formula (3-1).

2. The method for producing a semiconductor substrate according to claim 1, wherein the partial structure is represented by the following formula (3-1-1), (3-1-2), (3-1-3) or (3-2-1).

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

4. The method for producing a semiconductor substrate according to claim 3, wherein the repeating unit (1) is a repeating unit represented by the formula (1-1).

5. The method for producing a semiconductor substrate according to claim 1 or 2, wherein the resist film contains a metal.

6. The method for producing a semiconductor substrate according to claim 5, 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.

7. The method for producing a semiconductor substrate according to claim 1 or 2, wherein the content of the repeating unit (1) in all repeating units constituting the polymer is 1 mol % or more and 50 mol % or less.

8. The method for producing a semiconductor substrate according to claim 1 or 2, wherein the content of the repeating unit (2) in all repeating units constituting the polymer is 1 mol % or more and 80 mol % or less.

9. The method for producing a semiconductor substrate according to claim 1 or 2, wherein the content of said repeating unit (3) in all repeating units constituting said polymer is 1 mol % or more and 80 mol % or less.

10. The method for manufacturing a semiconductor substrate according to claim 1 or 2, wherein the radiation is an electron beam or extreme ultraviolet light.

11. A composition for forming a resist underlayer film, comprising: a polymer; and a solvent, wherein the polymer contains: a repeating unit (1) having an organic sulfonate anion moiety and an onium cation moiety; a repeating unit (2) represented by the following formula (2); and a repeating unit (3) represented by the following formula (3): (In formula (2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ R is a single bond or a divalent linking group. ４ 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 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 (2-1) to (2-8), R ７ is a divalent organic group having 1 to 20 carbon atoms or a single bond. * is L ３ is a bond to the atoms that make up the molecule.) (In formula (3), R ５ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４ R is a single bond or a divalent linking group. ６ is a group containing a partial structure represented by the following formula (3-1) or (3-2): (In the formulas (3-1) and (3-2), X １ and X ２ are each independently an oxygen atom, a sulfur atom, or a nitrogen atom. １ Between C on the left side of the formula and X ２ and C on the right side of the formula each independently represent a single bond or a double bond, except when formula (3-2) corresponds to formula (3-1).

12. The composition for forming a resist underlayer film according to claim 11, wherein the partial structure is represented by the following formula (3-1-1), (3-1-2), (3-1-3) or (3-2-1).

13. The composition for forming a resist underlayer film according to claim 11 or 12, wherein the repeating unit (1) is a repeating unit represented by the following formula (1-1) or (1-2): (In formula (1-1), R ａ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a divalent linking group. １ is a single bond or a divalent organic group having 1 to 40 carbon atoms. １ ＋ is a monovalent onium cation. ａ and L ２ are R in the above formula (1-1). ａ and L １ It is synonymous with Z. ２ ＋ R is a monovalent group having a monovalent onium cation structure. ２ is a monovalent organic group having 1 to 40 carbon atoms.

14. The composition for forming a resist underlayer film according to claim 13, wherein the repeating unit (1) is a repeating unit represented by the formula (1-1).

15. A composition for forming a resist underlayer film according to claim 11 or 12, wherein the content of the repeating unit (1) in all repeating units constituting the polymer is 1 mol % or more and 50 mol % or less.

16. A composition for forming a resist underlayer film according to claim 11 or 12, wherein the content of the repeating unit (2) in all repeating units constituting the polymer is 1 mol % or more and 80 mol % or less.

17. A composition for forming a resist underlayer film according to claim 11 or 12, wherein the content of the repeating unit (3) in all repeating units constituting the polymer is 1 mol % or more and 80 mol % or less.

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