Resist underlayer film-forming composition and method for manufacturing semiconductor substrate

Abstract

Provided are a resist underlayer film-forming composition with which it is possible to form a resist underlayer film having excellent solvent resistance and excellent resist pattern rectangularity, and a method for manufacturing a semiconductor substrate. The resist underlayer film-forming composition contains a polymer having a repeating unit represented by formula (1), and a solvent. (In formula (1), R1 represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. L1 represents a 1+n-valent linking group. Ar1 represents a monovalent group having an aromatic ring having 6 to 20 ring members. The aromatic ring has at least one halogen atom. n represents an integer of 1 to 3. When n is 2 or more, a plurality of the Ar1s are the same as or different from one another. L1 has at least one group (A) selected from the group consisting of a group represented by formula (2-1), a group represented by formula (2-2), a group represented by formula (2-3), a group represented by formula (2-4), a group represented by formula (2-5), a group represented by formula (2-6), a group represented by formula (2-7), and a group represented by formula (2-8).) (In formulae (2-1) to (2-8), R7 each independently represent a divalent organic group having 1 to 20 carbon atoms or a single bond. R8, R9, R10, and R13 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy represents a ring structure constituted together with two carbon atoms in formula (2-2) and having 3 to 20 ring members. R11 represents a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. R12 represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** represents a bond with an atom constituting Cy. Note that if R11 is a single bond, R11 is combined with **. * represents a bond with an atom constituting L1.)

Description

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

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

[0002] In the manufacture of semiconductor devices, for example, a multilayer resist process is used in which a resist pattern is formed by exposing and developing a resist film laminated on a substrate via a resist underlayer film such as an organic underlayer film or a silicon-containing film. In this process, the resist underlayer film is etched using the resist pattern as a mask, and the substrate is further etched using the resulting resist underlayer film pattern as a mask, thereby forming a desired pattern on the semiconductor substrate.

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

[0004] International Publication No. 2013 / 141015

[0005] The resist underlayer film is required to have solvent resistance to the solvent in the resist composition, and to have a resist pattern rectangularity that prevents 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, which is capable of forming a resist underlayer film that is excellent in solvent resistance and resist pattern rectangularity, and a method for producing a semiconductor substrate.

[0007] In one embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a polymer having a repeating unit represented by the following formula (1) (hereinafter also referred to as “polymer [A]”); and a solvent (hereinafter also referred to as “solvent [B]”). (In formula (1), R １is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group with a valence of 1+n. １ is a monovalent group having an aromatic ring with 6 to 20 ring members. The aromatic ring has at least one halogen atom. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ar １ are the same or different. １ has at least one group (A) selected from the group consisting of a group represented by the following formula (2-1), a group represented by the following formula (2-2), a group represented by the following formula (2-3), a group represented by the following formula (2-4), a group represented by the following formula (2-5), a group represented by the following formula (2-6), a group represented by the following formula (2-7), and a group represented by the following formula (2-8). (In formulas (2-1) to (2-8), R ７ are each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. ８ , R ９ , R １０ and R １３ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in formula (2-2). R １１ is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** is a bond to an atom constituting Cy. However, R １１ is a single bond, R １１ * is combined with L １ is the bond to the atoms that make up the atom.)

[0008] In another embodiment, the present invention provides 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 applying a composition for forming a resist film to the resist underlayer film formed in the step of applying the composition for forming a resist film; a step of exposing the resist film formed in the step of applying the composition for forming a resist film to radiation; and a step of developing at least the exposed resist film, wherein the composition for forming a resist underlayer film comprises: a polymer having a repeating unit represented by the following formula (1); and a solvent. (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group with a valence of 1+n. １ is a monovalent group having an aromatic ring with 6 to 20 ring members. The aromatic ring has at least one halogen atom. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ar １ are the same or different. １ has at least one group (A) selected from the group consisting of a group represented by the following formula (2-1), a group represented by the following formula (2-2), a group represented by the following formula (2-3), a group represented by the following formula (2-4), a group represented by the following formula (2-5), a group represented by the following formula (2-6), a group represented by the following formula (2-7), and a group represented by the following formula (2-8). (In formulas (2-1) to (2-8), R ７ are each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. ８ , R ９ , R １０ and R １３ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in formula (2-2). R １１ is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** is a bond to an atom constituting Cy. However, R １１is a single bond, R １１ * is combined with L １ is the bond to the atoms that make up the atom.)

[0009] The composition for forming a resist underlayer film can form a film that is excellent in solvent resistance and resist pattern rectangularity. The method for producing a semiconductor substrate uses a composition for forming a resist underlayer film that can form a resist underlayer film that is excellent in solvent resistance and resist pattern rectangularity, allowing semiconductor substrates to be produced efficiently. Therefore, these compositions can be suitably used in the production of semiconductor devices, etc.

[0010] The composition for forming a resist underlayer film and the method for producing a semiconductor substrate according to each embodiment of the present invention will be described in detail below. Combinations of preferred aspects in the embodiments are also preferred.

[0011] <<Composition for forming a resist underlayer film>> The composition for forming a resist underlayer film (hereinafter also referred to as the “composition”) contains a polymer (A) and a solvent (B). The composition may contain optional components as long as the effects of the present invention are not impaired.

[0012] This composition is suitable as a composition for forming an underlayer film of a resist film to be exposed to extreme ultraviolet radiation. Examples of resist film-forming compositions include positive- or negative-type chemically amplified resist compositions containing a radiation-sensitive acid generator, positive-type resist compositions containing an alkali-soluble resin and a quinone diazide photosensitizer, negative-type resist compositions containing an alkali-soluble resin and a crosslinker, and metal-containing resist compositions containing metals such as tin, zirconium, and hafnium. The underlayer film formed using this composition contains halogen atoms derived from the polymer [A], thereby increasing the efficiency of secondary electron generation due to absorption of extreme ultraviolet radiation. As a result, upon exposure to extreme ultraviolet radiation, a sufficient difference in solubility occurs in the interface region of the organic resist film on the underlayer film side, and the insolubilization of the metal-containing resist film is promoted, thereby suppressing pattern tailing at the bottom of the resist film and ensuring rectangularity of the resist pattern. Furthermore, since the polymer [A] contains the specific group (A), a crosslinked structure is formed in the resulting resist underlayer film, reducing its solubility in organic solvents. The lower limit of the content of the metal or metal compound in the components other than the solvent in the metal-containing resist composition is preferably 50 mass %, more preferably 70 mass %, even more preferably 80 mass %, and particularly preferably 85 mass %. The upper limit of the content is, for example, 100 mass % or 95 mass %.

[0013] Each component contained in the composition will be described below.

[0014] <Polymer [A]> The polymer [A] has a repeating unit represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"). The polymer [A] can contain one or two or more types of repeating unit (1). The polymer [A] may have a repeating unit other than the repeating unit (1). The composition can contain one or two or more types of polymer [A]. (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group with a valence of 1+n. １is a monovalent group having an aromatic ring with 6 to 20 ring members. The aromatic ring has at least one halogen atom. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ar １ are the same or different. １ has at least one group (A) selected from the group consisting of a group represented by the following formula (2-1), a group represented by the following formula (2-2), a group represented by the following formula (2-3), a group represented by the following formula (2-4), a group represented by the following formula (2-5), a group represented by the following formula (2-6), a group represented by the following formula (2-7), and a group represented by the following formula (2-8). (In formulas (2-1) to (2-8), R ７ are each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. ８ , R ９ , R １０ and R １３ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in formula (2-2). R １１ is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** is a bond to an atom constituting Cy. However, R １１ is a single bond, R １１ * is combined with L １ is the bond to the atoms that make up the atom.)

[0015] In the above formula (1), R １ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is not particularly limited, and examples thereof include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and combinations thereof.

[0016] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and neopentyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0017] 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.

[0018] 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, a pyrenyl group, a fluorenyl group, and a 9-methylidenefluorenyl group.

[0019] R １ When has a substituent, examples of the substituent include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, an alkoxycarbonyl group such as a methoxycarbonyl group or an ethoxycarbonyl group, an alkoxycarbonyloxy group such as a methoxycarbonyloxy group or an ethoxycarbonyloxy group, an acyl group such as a formyl group, an acetyl group, a propionyl group, or a butyryl group, a cyano group, and a nitro group.

[0020] Among them, R １ In terms of copolymerizability of the monomer that gives the repeating unit (1), a hydrogen atom or a methyl group is preferred.

[0021] In the above formula (1), L １Examples of the divalent linking group represented by the formula (I) include a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent heteroatom-containing group, a group having the divalent heteroatom-containing group between carbon atoms in the divalent hydrocarbon group having 1 to 20 carbon atoms, a group in which some or all of the hydrogen atoms in the hydrocarbon group have been substituted with monovalent heteroatom-containing groups, and combinations thereof.

[0022] The divalent hydrocarbon group having 1 to 20 carbon atoms includes the above-mentioned R １ A group in which one hydrogen atom has been removed from a monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by the following formula: can be suitably used. As the divalent hydrocarbon group having 1 to 20 carbon atoms, an alkanediyl group having 1 to 10 carbon atoms, an arenediyl group having 6 to 10 carbon atoms, or a combination thereof is preferred.

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

[0024] Examples of the divalent heteroatom-containing group include —CO—, —CS—, —NR′—, —O—, —S—, and —SO ２ - or a group combining these. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Preferred divalent hetero atom-containing groups are -O-, -COO-, -NH-, and -S-.

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

[0026] L １ The divalent linking group represented by the formula (I) is preferably an alkanediyl group having 1 to 10 carbon atoms, a divalent heteroatom-containing group, an arenediyl group having 6 to 10 carbon atoms, or a combination thereof, and more preferably a combination of an alkanediyl group having 1 to 10 carbon atoms and a divalent heteroatom-containing group, or a combination of an alkanediyl group having 1 to 10 carbon atoms, a divalent heteroatom-containing group, and an arenediyl group having 6 to 10 carbon atoms.

[0027] In the above formulas (2-1) to (2-8), R ７ The divalent organic group having 1 to 20 carbon atoms represented by the formula (1) is L １ A divalent linking group represented by the following formula can be preferably used.

[0028] R ７ As the alkyl group, a combination of a divalent hydrocarbon group having 1 to 10 carbon atoms and a divalent heteroatom-containing group is preferred, and a combination of a methanediyl group, an ethanediyl group, a propanediyl group, a benzenediyl group, or a combination thereof with —O—, —CO—, or a combination thereof is more preferred.

[0029] In the above formulas (2-1) to (2-3), R ８ , R ９ , R １０ , R １１ , R １２ and R １３ (Hereinafter referred to as “R ８ ~R １３ "). Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the end of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing group, or a combination thereof. The "organic group" is a group having at least one carbon atom.

[0030] R ８ ~R １３ The monovalent hydrocarbon group having 1 to 20 carbon atoms in the formula (1) is R １ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0031] R ８ ~R １３ The divalent heteroatom-containing group and the monovalent heteroatom-containing group in the formula (1) are １ A divalent heteroatom-containing group and a monovalent heteroatom-containing group in the above formula can be suitably employed.

[0032] R ８ ~R １３are preferably all hydrogen atoms.

[0033] 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 １ Preferably, Cy is a cycloalkane ring having 5 to 10 carbon atoms, more preferably a cyclopentane ring, a cyclohexane ring, or a cycloheptane ring.

[0034] Specific examples of the group represented by the above formula (2-1) include structures represented by the following formulas (2-1-1) to (2-1-10).

[0035] Specific examples of the group represented by the above formula (2-2) include structures represented by the following formulas (2-2-1) to (2-2-6).

[0036] Specific examples of the group represented by the above formula (2-3) include structures represented by the following formulas (2-3-1) to (2-3-6).

[0037] Specific examples of the group represented by the above formula (2-4) include structures represented by the following formulas (2-4-1) to (2-4-6).

[0038] Specific examples of the group represented by the above formula (2-5) include structures represented by the following formulas (2-5-1) to (2-5-6).

[0039] Specific examples of the group represented by the above formula (2-6) include structures represented by the following formulas (2-6-1) to (2-6-3).

[0040] Specific examples of the group represented by the above formula (2-7) include structures represented by the following formulas (2-7-1) to (2-7-2).

[0041] Specific examples of the group represented by the above formula (2-8) include structures represented by the following formulas (2-8-1) to (2-8-2).

[0042] In the above formula (1), L １ is preferably represented by the following formula (3-1) or (3-2). (In the above formula (3-1), Ar ２ is a 1+n valent group having an aromatic ring with 6 to 20 ring members. s1 is 0 or 1. When there are multiple s1s, the multiple s1s may be the same or different. X １ and X ２ are each independently —O—, —NH—, or —S—, provided that when s1 is 1, X ２ is —O—. X １ and X ２ If there are multiple Xs, １ and X ２ are the same or different. n has the same meaning as in the above formula (1). In the above formula (3-2), s2 is 0 or 1. X ３ is —O—, —NH—, or —S—. However, when s2 is 1, X ３ In the above formulas (3-1) and (3-2), * represents R in the above formula (1). １ is a bond to the carbon atom to which Ar is bonded. ** is a bond to the group (A). *** is a bond to the Ar １ It is a bond with

[0043] In the above formula (3-1), Ar ２ Examples of the aromatic ring having 6 to 20 ring members in Ar include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, an indene ring, and a pyrene ring, aromatic heterocyclic rings such as a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring, and combinations thereof. １ The aromatic ring is preferably a benzene ring, a naphthalene ring, an anthracene ring or a pyrene ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

[0044] Ar ２As the (1+n) valent group having an aromatic ring with 6 to 20 ring members represented by the following formula, a group in which (1+n) hydrogen atoms have been removed from the above aromatic ring with 6 to 20 ring members can be suitably used.

[0045] Ar ２ is R in the above formula (1). １ Ar may have a substituent that Ar may have. ２ When has a substituent, the substituent is preferably a halogen atom, more preferably an iodine atom.

[0046] X １ and X ２ are preferably both —O—.

[0047] n is preferably 1 or 2, and more preferably 1.

[0048] In the above formula (3-2), X ３ is preferably —O—.

[0049] In the above formula (1), Ar １ The aromatic ring having 6 to 20 ring members in the above formula (3-1) includes Ar ２ An aromatic ring having 6 to 20 ring members can be suitably used.

[0050] The aromatic ring has at least one halogen atom. The aromatic ring may have two or three halogen atoms. In this case, the multiple halogen atoms may be the same or different. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. The halogen atom is preferably an iodine atom.

[0051] Specific examples of the monomer that gives the repeating unit (1) include compounds represented by the following formulas (1-1) to (1-35).

[0052]

[0053]

[0054]

[0055] In the above formulas (1-1) to (1-35), R １is synonymous with the above formula (1).

[0056] The lower limit of the content of the repeating unit (1) in all repeating units constituting the polymer [A] (the total content when multiple types are present) is preferably 10 mol%. The lower limit of the content may be 20 mol%, 30 mol%, or 40 mol%. The upper limit of the content may be 100 mol%, i.e., the polymer [A] may be a homopolymer of the repeating unit (1). When the polymer [A] is a copolymer, the upper limit of the content of the repeating unit (1) may be 99 mol%, 95 mol%, or 90 mol%.

[0057] The polymer [A] may further have a repeating unit represented by the following formula (4) (excluding the case of the above formula (1)) (hereinafter also referred to as "repeating unit (2)"). The polymer [A] may have one or more types of repeating unit (2). (In formula (2), R ４３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４３ is a single bond or a divalent linking group. ４４ is the above group (A).

[0058] R ４３ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is １ The groups listed as examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the above R ４３ When R has a substituent, the substituent is R １ The substituents that may be possessed by the group can be suitably employed.

[0059] L ４３ The divalent linking group represented by the formula (1) is １ Examples of the divalent linking group include the groups listed above as the divalent linking group represented by the formula: ４３ As the group, a single bond, -COO- ＊ ( ＊ is R ４４ is a bond to the aryl group.) or a benzenediyl group is preferred.

[0060] Specific examples of the repeating unit (2) include repeating units represented by the following formulas (4-1) to (4-16).

[0061]

[0062] In the above formulas (4-1) to (4-16), R ４３ is the same as the above formula (4).

[0063] When the polymer [A] contains the repeating unit (2), the lower limit of the content of the repeating unit (2) relative to all repeating units constituting the polymer [A] (the total content when multiple types are included) is preferably 1 mol%, more preferably 20 mol%, and even more preferably 30 mol%. The upper limit of this content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of the repeating unit (2) within the above range, high levels of solvent resistance and resist pattern rectangularity can be achieved.

[0064] The polymer [A] may contain, as other repeating units (excluding those represented by formula (1)), repeating units containing a structure that generates acid upon exposure, such as an onium salt structure containing a sulfonate anion and a sulfonium cation, or an onium salt structure containing a sulfonate anion and an iodonium cation, a repeating unit having at least one hydroxy group, or a repeating unit having a fluorine atom. When the polymer [A] contains other repeating units, the lower limit of the content of the other repeating units (the total content when multiple types are present) relative to all repeating units constituting the polymer [A] is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%.

[0065] The lower limit of the weight-average molecular weight of the polymer (A) is preferably 2000, more preferably 3000, even more preferably 4000, and particularly preferably 5000. The upper limit of the molecular weight is preferably 15000, more preferably 12000, even more preferably 10000, and particularly preferably 8000. The method for measuring the weight-average molecular weight is as described in the Examples.

[0066] The lower limit of the polydispersity index (PDI: Mw / Mn) of the polymer (A) is usually 1, and more preferably 1.1. The upper limit of the PDI is usually 5, and preferably 3, and more preferably 2.

[0067] The lower limit of the content of the polymer [A] in the composition for forming a resist underlayer film is preferably 0.05 mass %, more preferably 0.1 mass %, even more preferably 0.15 mass %, and particularly preferably 0.2 mass %, based on the total mass of the polymer [A] and the solvent [B]. The upper limit of the content is preferably 1 mass %, more preferably 0.8 mass %, even more preferably 0.6 mass %, and particularly preferably 0.4 mass %, based on the total mass of the polymer [A] and the solvent [B].

[0068] The lower limit of the content of the polymer (A) in the components other than the solvent (B) in the composition for forming a resist underlayer film is preferably 40% by mass, more preferably 50% by mass, and even more preferably 60% by mass. The upper limit of the content is preferably 100% by mass, but may also be 90% by mass or 85% by mass.

[0069] [Method for Synthesizing Polymer [A]] The polymer [A] can be synthesized by radical polymerization, ionic polymerization, polycondensation, polyaddition, addition condensation, etc., depending on the type of monomer. For example, when the polymer [A] is synthesized by radical polymerization, the polymer can be synthesized by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator, etc.

[0070] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate, and dimethyl-2,2'-azobis(2-methylpropionate); and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. These radical initiators can be used alone or in combination of two or more.

[0071] As the solvent used in the polymerization, the solvent [B] described below can be suitably used. These solvents used in the polymerization may be used alone or in combination of two or more kinds.

[0072] 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.

[0073] <Solvent (B)> The solvent (B) is not particularly limited as long as it can dissolve or disperse the polymer (A) and any optional components contained as needed.

[0074] Examples of the solvent (B) include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, etc. The solvent (B) can be used alone or in combination of two or more.

[0075] 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.

[0076] 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.

[0077] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, 4-methyl-2-pentanol, and 2,2-dimethyl-1-propanol, and polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0078] 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.

[0079] 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.

[0080] Examples of nitrogen-containing solvents include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0081] The solvent (B) is preferably a ketone solvent, an ether solvent, or an ester solvent, more preferably a cyclic ketone solvent, a polyhydric alcohol partial ether solvent, or a polyhydric alcohol partial ether carboxylate solvent, and still more preferably cyclohexanone, propylene glycol monomethyl ether, or propylene glycol monomethyl ether acetate.

[0082] [Optional Components] The composition for forming a resist underlayer film may contain optional components within a range that does not impair the effects of the present invention. Examples of optional components include a crosslinking agent, an acid generator, a dehydrating agent, an acid diffusion controller, a surfactant, etc. The optional components may be used alone or in combination of two or more. The content of the optional components relative to the total mass of the polymer [A] and the optional components is preferably 30 mass% or less, and more preferably 20 mass% or less.

[0083] [Method for preparing a composition for forming a resist underlayer film] The composition for forming a resist underlayer film can be prepared by mixing the polymer [A], the solvent [B], and, if necessary, any optional components in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter or the like having a pore size of 0.5 μm or less.

[0084] <<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 “coating step (I)”), a step of applying a composition for forming a resist film to the resist underlayer film formed in the above-mentioned coating step of the composition for forming a resist film (hereinafter also referred to as a “coating step (II)”), a step of exposing the resist film formed in the above-mentioned coating step of the composition for forming a 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”).

[0085] According to the method for producing a semiconductor substrate, by using a predetermined composition for forming a resist underlayer film in the coating step (I), a resist underlayer film having excellent solvent resistance and resist pattern rectangularity can be formed, and therefore a semiconductor substrate having a good pattern shape can be produced.

[0086] It is preferable that the method for producing a semiconductor substrate further includes, before the coating step (II), a step of heating the resist underlayer film formed in the resist underlayer film-forming composition coating step at 200°C or higher (hereinafter also referred to as a "heating step").

[0087] The method for producing a semiconductor substrate may further include, as necessary, a step of forming a silicon-containing film directly or indirectly on the substrate (hereinafter also referred to as a "silicon-containing film-forming step") prior to the coating step (I).

[0088] Hereinafter, each step in the case where the heating step, which is a preferred step, and the silicon-containing film forming step, which is an optional step, are included will be described.

[0089] [Silicon-containing film forming step] In this step, which is carried out before the coating step (I), a silicon-containing film is formed directly or indirectly on a substrate.

[0090] Examples of the substrate include metal or semimetal substrates such as silicon substrates, aluminum substrates, nickel substrates, chromium substrates, molybdenum substrates, tungsten substrates, copper substrates, tantalum substrates, and titanium substrates, among which silicon substrates are preferred.The substrate may also be a substrate on which a silicon nitride film, an alumina film, a silicon dioxide film, a tantalum nitride film, a titanium nitride film, or the like is formed.

[0091] The silicon-containing film can be formed by coating a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. Examples of methods for forming a silicon-containing film by coating a silicon-containing film-forming composition include a method in which the silicon-containing film-forming composition is directly or indirectly applied to a substrate, and the resulting coating film is then cured by exposure and / or heating. Examples of commercially available silicon-containing film-forming compositions include "NFC SOG01," "NFC SOG04," and "NFC SOG080" (all from JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxynitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0092] Examples of radiation used for the exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays and gamma rays, and particle beams such as electron beams, molecular beams and ion beams.

[0093] The lower limit of the temperature when heating the coating film is preferably 90° C., more preferably 150° C., and still more preferably 200° C. The upper limit of the temperature is preferably 550° C., more preferably 450° C., and still more preferably 300° C.

[0094] The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and even more preferably 15 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm. The average thickness of the silicon-containing film can be measured in the same manner as the average thickness of the resist underlayer film.

[0095] Examples of cases where a silicon-containing film is formed indirectly on a substrate include cases where a silicon-containing film is formed on a low dielectric insulating film or an organic underlayer film formed on a substrate.

[0096] [Coating step (I)] In this step, the resist underlayer film-forming composition is coated on the silicon-containing film formed on the substrate.The coating method of the resist underlayer film-forming composition is not particularly limited, and can be carried out by any suitable method such as spin coating, casting coating, roll coating, etc.This forms a coating film, and the resist underlayer film is formed by the evaporation of the solvent [B].

[0097] 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 50 nm, more preferably 20 nm, even more preferably 10 nm, and particularly preferably 7 nm. The average thickness is measured according to the method described in the Examples.

[0098] When the composition for forming a resist underlayer film is applied directly to the substrate, the silicon-containing film forming step may be omitted.

[0099] [Heating Step] Next, the resist underlayer film formed in the coating step (I) is heated. Heating the resist underlayer film promotes the formation of a crosslinked structure by the specific group in the polymer (A). This step is carried out before the coating step (II).

[0100] The coating film may be heated in an air atmosphere or a nitrogen atmosphere. The lower limit of the heating temperature is 180°C, but is preferably 200°C, more preferably 210°C, and even more preferably 220°C. The upper limit of the heating temperature is preferably 400°C, more preferably 350°C, and even more preferably 280°C. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds. The upper limit of the time is preferably 800 seconds, more preferably 400 seconds, and even more preferably 200 seconds.

[0101] [Coating Step (II)] In this step, a resist film-forming composition is coated onto the resist underlayer film formed in the resist underlayer film-forming composition coating step. The method for coating the resist film-forming composition is not particularly limited, and examples thereof include a rotary coating method.

[0102] To explain this step in more detail, for example, a resist composition is applied so that the resist film to be formed has a predetermined thickness, and then the applied resist film is pre-baked (hereinafter also referred to as "PB") to volatilize the solvent in the applied film, thereby forming the resist film.

[0103] The PB temperature and PB time can be appropriately determined depending on the type of the resist film-forming composition used, etc. The lower limit of the PB temperature is preferably 30°C, more preferably 50°C. The upper limit of the PB temperature is preferably 200°C, more preferably 150°C. The lower limit of the PB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PB time is preferably 600 seconds, more preferably 300 seconds.

[0104] The resist film-forming composition used in this step is preferably a composition that is subjected to exposure to extreme ultraviolet rays, and examples thereof include positive or negative chemically amplified resist compositions that contain a radiation-sensitive acid generator, and negative metal-containing resist compositions that contain a metal such as tin, zirconium, or hafnium.

[0105] [Exposure Step] In this step, the resist film formed in the resist film-forming composition application step is exposed to radiation. This step generates a difference in solubility in a basic liquid, which is a developer, between the exposed and unexposed areas of the resist film. More specifically, the solubility of the exposed areas of the resist film in a basic liquid is increased.

[0106] The radiation used for exposure can be appropriately selected depending on the type of the resist film-forming composition used, etc. Examples include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, and particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, and 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 ArF excimer laser light or EUV is even more preferred. The exposure conditions can be appropriately determined depending on the type of resist film-forming composition used, etc.

[0107] 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.

[0108] [Development Step] In this step, the exposed resist film is developed. At this time, a part of the resist underlayer film may also be developed. Examples of the developer used in this development include an alkaline aqueous solution (alkaline developer), a liquid containing an organic solvent (organic solvent developer), etc.

[0109] 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.

[0110] Examples of organic solvent developers for use in organic solvent development include those exemplified above as the solvent [B]. As the organic solvent developer, an ester solvent, an ether solvent, an alcohol solvent, a ketone solvent, and / or a hydrocarbon solvent is preferred, a ketone solvent is more preferred, and 2-heptanone is particularly preferred.

[0111] In this step, washing and / or drying may be carried out after the development.

[0112] [Etching Step] In this step, etching is performed using the resist pattern (and resist underlayer film pattern) as a mask. The etching may be performed once or multiple times, i.e., etching may be performed sequentially using the pattern obtained by etching as a mask. From the viewpoint of obtaining a pattern with a better shape, multiple times is preferred. When etching is performed multiple times, for example, etching is performed sequentially in the order of the silicon-containing film and the substrate. Examples of etching methods include dry etching and wet etching. From the viewpoint of obtaining a better pattern shape on the substrate, dry etching is preferred. For this dry etching, for example, a gas plasma such as oxygen plasma is used. By the above etching, a semiconductor substrate having a predetermined pattern is obtained.

[0113] Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the mask pattern, the elemental composition of the film to be etched, etc., and can be, for example, CHF ３ , C.F. ４ , C ２ F ６ , C ３ F ８ , SF ６ Fluorine-based gases such as Cl ２ , BCl ３ Chlorine gases such as O ２ , O ３ , H ２ Oxygen-based gases such as O, H ２ , N.H. ３ , CO, CO ２ , C.H. ４ , C ２ H ２ , C ２ H ４ , C ２ H ６ , C ３ H ４ , C ３ H ６ , C ３ H ８ , HF, HI, HBr, HCl, NO, BCl ３ reducing gases such as He, N ２ and inert gases such as Ar. These gases may be used in combination. When etching a substrate using the pattern of the resist underlayer film as a mask, a fluorine-based gas is usually used.

[0114] After the substrate pattern is formed, if the silicon-containing film remains on the substrate, the silicon-containing film can be removed by carrying out a removal step.

[0115] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0116] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), polydispersity index (PDI: Mw / Mn)] 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.

[0117] [Average Film Thickness] The average film thickness was determined by measuring the film thickness at 9 arbitrary positions at 5 cm intervals, including the center of the resist underlayer film formed on a silicon wafer (substrate), using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"), and calculating the average of these film thicknesses.

[0118] <Synthesis of Polymer [A]> Polymer [A] having repeating units represented by the following formulae (A-1) to (A-44) was synthesized according to the procedure shown below. In the formulae, the number attached to each repeating unit indicates the content (mol %) of that repeating unit. The composition ratio is １３ This was confirmed by C-NMR.

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] <Synthesis of Monomers> The following compounds (a-1) to (a-23) were used as monomers in the synthesis of polymer (A).

[0129]

[0130]

[0131] As raw materials for synthesizing the above monomers, the following compounds (f-1) to (f-7), the following compounds (g-1) to (g-11), and the following compounds (h-1) to (h-4) were used.

[0132]

[0133]

[0134]

[0135] Synthesis Example 1-1 (Synthesis of Compound (a-1)) 5.00 g of compound (f-1), 6.24 g of compound (g-1), 0.57 g of triethylamine, and 30 g of ethanol were added to a reaction vessel and stirred at 60°C for 6 hours. Thereafter, 2.63 g of compound (h-1) and 3.92 g of potassium carbonate were added and stirred at 60°C for 8 hours. After completion of the reaction, 200 g of ultrapure water was added to obtain a precipitate. This was dissolved in 40 g of methyl ethyl ketone and purified by precipitation with a five-fold amount of heptane, obtaining 11 g of compound (a-1) as a white solid.

[0136] [Synthesis Examples 1-2 to 1-5, 1-8 to 1-14] (Synthesis of Compounds (a-2) to (a-5), and (a-8) to (a-14))] Compounds (a-2) to (a-5) and (a-8) to (a-14) were synthesized in the same manner as for compound (a-1), except that compound [f], compound [g], and compound [h] shown in Table 1 were used. The yields (%) of the obtained compounds [a] are also shown in Table 1.

[0137] Synthesis Example 1-6 Synthesis of Compound (a-6) 5.00 g of compound (f-1), 6.22 g of compound (g-3), and 30 g of ethanol were added to a reaction vessel and stirred at 60°C for 6 hours. Thereafter, 2.63 g of compound (h-1) and 3.92 g of potassium carbonate were added and stirred at 60°C for 8 hours. After completion of the reaction, 200 g of ultrapure water was added to obtain a precipitate. This was dissolved in 40 g of methyl ethyl ketone and purified by precipitation with a five-fold amount of heptane to obtain 9.7 g of compound (a-6) as a white solid.

[0138] Synthesis Example 1-7 Synthesis of Compound (a-7) 5.00 g of compound (f-1), 6.70 g of compound (g-4), 2.87 g of triethylamine, and 30 g of ethanol were added to a reaction vessel and stirred at 60°C for 6 hours. Thereafter, 2.63 g of compound (h-1) and 3.92 g of potassium carbonate were added and stirred at 60°C for 8 hours. After completion of the reaction, 200 g of ultrapure water was added to obtain a precipitate. This was dissolved in 40 g of methyl ethyl ketone and purified by precipitation with a five-fold amount of heptane, obtaining 9.7 g of compound (a-7) as a white solid.

[0139] [Synthesis Examples 1-15 to 1-23] (Synthesis of Compounds (a-15) to (a-23))] Compounds (a-15) to (a-23) were synthesized in the same manner as for compound (a-1), except that compounds [f], [g], and [h] shown in Table 1 were used. The yields (%) of the obtained compounds [a] are also shown in Table 1.

[0140]

[0141] The following compounds (b-1) to (b-4), (c-1) to (c-5), (d-1) to (d-6), and (e-1) to (e-2) were used as monomers in the synthesis of polymer [A].

[0142]

[0143]

[0144]

[0145]

[0146] Synthesis Example 2-1 Synthesis of Polymer (A-1) 6 g of 2-methoxy-1-methylethyl acetate was placed in a reaction vessel and kept at 80°C, and a mixed solution of 6.00 g of compound (a-1), 0.62 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 2-methoxy-1-methylethyl acetate 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 obtained polymerization solution was purified by precipitation with a 5-fold amount of methanol, and 5.2 g of polymer (A-1) was obtained as a white solid.

[0147] [Synthesis Examples 2-2 to 2-23] (Synthesis of Polymers (A-2) to (A-23)) Polymers (A-2) to (A-23) were synthesized in the same manner as for polymer (A-1), except that the compound [a] shown in Table 2 was used. The Mw, Mn, and PDI of the obtained polymer [A] are also shown in Table 2. In Table 2, "-" indicates that the corresponding component was not used. The same applies to the subsequent tables.

[0148] Synthesis Example 2-24 Synthesis of Polymer (A-24) 6 g of 2-methoxy-1-methylethyl acetate was placed in a reaction vessel and kept at 80°C, and a mixed solution of 4.96 g of compound (a-1), 1.04 g of compound (b-1), 0.62 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 2-methoxy-1-methylethyl acetate 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 obtained polymerization solution was purified by precipitation with a 5-fold amount of methanol, and 5.2 g of polymer (A-24) was obtained as a white solid.

[0149] [Synthesis Examples 2-25 to 2-27] (Synthesis of Polymers (A-25) to (A-27)) Polymers (A-25) to (A-27) were synthesized in the same manner as for polymer (A-24), except that the compounds [a] and [b] shown in Table 2 were used. The Mw, Mn, and PDI of the obtained polymers [A] are also shown in Table 2.

[0150] Synthesis Example 2-28 Synthesis of Polymer (A-28) 6 g of 2-methoxy-1-methylethyl acetate was placed in a reaction vessel and kept at 80°C, and a mixed solution of 4.26 g of compound (a-1), 0.67 g of compound (b-1), 1.07 g of compound (c-1), 0.72 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 2-methoxy-1-methylethyl acetate 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 obtained polymerization solution was precipitated and purified with a 5-fold amount of methanol, to obtain 5.1 g of polymer (A-28) as a white solid.

[0151] [Synthesis Examples 2-29 to 2-34] (Synthesis of Polymers (A-29) to (A-34)) Polymers (A-29) to (A-34) were synthesized in the same manner as for polymer (A-28), except that compound [a], compound [b], and compound [c] shown in Table 2 were used. The Mw, Mn, and PDI of the obtained polymer [A] are also shown in Table 2.

[0152] Synthesis Example 2-35 Synthesis of Polymer (A-35) 6 g of 2-methoxy-1-methylethyl acetate was placed in a reaction vessel and maintained at 80°C, and a mixed solution of 3.85 g of compound (a-1), 0.72 g of compound (b-1), 1.17 g of compound (c-1), 0.27 g of compound (d-1), 0.72 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 2-methoxy-1-methylethyl acetate 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 obtained polymerization solution was precipitated and purified with a 5-fold amount of methanol, to obtain 5.0 g of polymer (A-35) as a white solid.

[0153] [Synthesis Examples 2-36 to 2-41] (Synthesis of Polymers (A-36) to (A-41)) Polymers (A-36) to (A-41) were synthesized in the same manner as for polymer (A-35), except that compound [a], compound [b], compound [c], and compound [d] shown in Table 2 were used. The Mw, Mn, and PDI of the obtained polymer [A] are also shown in Table 2.

[0154] Synthesis Example 2-42 Synthesis of Polymer (A-42) 6 g of 2-methoxy-1-methylethyl acetate was placed in a reaction vessel and maintained at 80°C. A mixed solution of 1.95 g of compound (a-1), 0.92 g of compound (b-1), 1.48 g of compound (c-1), 0.35 g of compound (d-1), 1.25 g of compound (e-1), 0.99 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 2-methoxy-1-methylethyl acetate 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 obtained polymerization solution was precipitated and purified with a 5-fold amount of methanol, yielding 5.2 g of polymer (A-42) as a white solid.

[0155] [Synthesis Examples 2-43 to 2-44] (Synthesis of Polymers (A-43) to (A-44)) Polymers (A-43) to (A-44) were synthesized in the same manner as for polymer (A-42), except that compound [a], compound [b], compound [c], compound [d], and compound [e] shown in Table 2 were used. The Mw, Mn, and PDI of the obtained polymer [A] are also shown in Table 2.

[0156] <Synthesis of Polymer [x]> [Comparative Synthesis Example 1] (Synthesis of Polymer (x-1)) 3 g of dimethylacetamide was placed in a reaction vessel and maintained at 80°C, and a mixed solution of 3.00 g of 4-hydroxystyrene, 0.31 g of dimethyl-2,2-azobis(2-methylpropionate), and 6.00 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, yielding 2.50 g (yield: 75%) of polymer (x-1) represented by the following formula as a white solid. The resulting polymer (x-1) had Mw: 4500, Mn: 2800, and PDI: 1.6.

[0157]

[0158]

[0159] <Preparation of Composition> The polymer [A], polymer [E], solvent [B], acid generator [C], crosslinking agent [D], and polymer [x] used in the preparation of the composition are shown below.

[0160] [[A] Polymer] A-1 to A-44: Polymers (A-1) to (A-44) synthesized above

[0161] [[x] Polymer] x-1: Polymer (x-1) synthesized above

[0162] [B] Solvent: B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0163] [[C] Acid Generator] C-1: Compound represented by the following formula (C-1): C-2: Compound represented by the following formula (C-2): C-3: Compound represented by the following formula (C-3): C-4: Compound represented by the following formula (C-4):

[0164] [[D] Crosslinking Agent] D-1: Compound represented by the following formula (D-1) D-2: Compound represented by the following formula (D-2)

[0165] [Example 1-1] 50 parts by mass of (A-1) as the polymer [A] was dissolved in 7,900 parts by mass of (B-1) and 2,000 parts by mass of (B-2) as the solvent [B]. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare a composition (J-1).

[0166] [Examples 1-2 to 1-52 and Comparative Example 1-1] Compositions (J-2) to (J-52) and (CJ-1) were prepared in the same manner as in Example 1-1, except that the types and amounts of each component shown in Table 3 below were used.

[0167]

[0168] <Evaluation> Using the compositions prepared above, the solvent resistance and the rectangularity of the resist pattern formed by EUV exposure were evaluated by the following methods. The evaluation results are shown in Table 4 below.

[0169] [Solvent Resistance] The composition prepared above was applied to a 12-inch silicon wafer by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). Next, the wafer was heated at 250°C for 60 seconds in an air atmosphere, and then cooled at 23°C for 60 seconds to form a resist underlayer film with an average thickness of 5 nm, thereby obtaining a substrate with a resist underlayer film formed on the substrate. The obtained substrate with a resist underlayer film was immersed in cyclohexanone (23°C) for 1 minute. The average film thicknesses before and after immersion were measured. The absolute value of the value obtained by {(X-X0) / X0} x 100 was calculated, where X0 is the average thickness of the resist underlayer film before immersion and X is the average thickness of the resist underlayer film after immersion, and this was used as the film thickness change rate (%). The solvent resistance was evaluated as "A" (good) when the film thickness change rate was less than 1%, "B" (fairly good) when it was 1% or more but less than 10%, and "C" (poor) when it was 10% or more.

[0170] <Preparation of Resist Composition> Resist composition (R-1) was obtained by mixing 100 parts by mass of a polymer having a structural unit (1) derived from 4-hydroxystyrene, a structural unit (2) derived from styrene, and a structural unit (3) derived from 4-t-butoxystyrene (the proportions of the structural units were (1) / (2) / (3)=65 / 5 / 30 (mol %)), 1.0 part by mass of triphenylsulfonium trifluoromethanesulfonate as a radiation-sensitive acid generator, and 4,400 parts by mass of ethyl lactate and 1,900 parts by mass of propylene glycol monomethyl ether acetate as solvents, and filtering the resulting solution through a filter with a pore size of 0.2 μm.

[0171] [Resist pattern rectangularity (EUV exposure)] An organic underlayer film forming material (JSR Corporation's "HM8006") was applied to a 12-inch silicon wafer by a spin coating method using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. A silicon-containing film-forming composition (JSR Corporation's "NFC SOG080") was applied to this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a silicon-containing film with an average thickness of 20 nm. The composition prepared above was applied to the silicon-containing film formed above to form a resist underlayer film. The resist underlayer film formed above was heated at 250°C for 90 seconds, and then cooled at 23°C for 30 seconds to obtain a resist underlayer film with an average thickness of 5 nm. Resist composition (R-1) was applied onto the resist underlayer film formed above, heated at 130° C. for 60 seconds, and then cooled at 23° C. for 30 seconds to form a resist film with an average thickness of 50 nm. Next, the resist film was irradiated with extreme ultraviolet rays using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line and space mask with a line width of 16 nm on the wafer). After irradiation with extreme ultraviolet rays, the substrate was heated at 110°C for 60 seconds and then cooled at 23°C for 60 seconds. Thereafter, the substrate was developed by the puddle method using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (20°C to 25°C), followed by washing with water and drying to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Technologies Corporation's "SU8220") was used to measure and observe the resist pattern of the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, and as "B" (poor) when there was a footing on the cross-section of the pattern.

[0172]

[0173] <Evaluation> Using the compositions prepared above, the rectangularity of resist patterns obtained by EUV exposure was evaluated by the following method. The evaluation results are shown in Table 5 below.

[0174] <Preparation of Resist Composition (R-2)> 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 mixture was stirred 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 an oxide hydroxide product (i-PrSnO) of the hydrolysis product of isopropyltin trichloride. （３／２－ｘ／２） (OH) ｘ (where 0<x<3 is the structural unit).

[0175] 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).

[0176] [Resist 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, and then 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, the resist composition was heated at 90°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 35 nm. The resist film was exposed to light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line and space mask with on-wafer line width of 16 nm). After exposure, the substrate was heated at 110°C for 60 seconds and then cooled at 23°C for 60 seconds. Thereafter, the substrate was developed using 2-heptanone (20 to 25°C) by a puddle method and then dried to obtain an evaluation substrate on which a resist pattern had been formed. A scanning electron microscope (Hitachi High-Tech's "CG-6300") was used to measure and observe the resist pattern of the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, and as "B" (poor) when there was a footing on the cross section of the pattern.

[0177]

[0178] As can be seen from the results in Tables 4 and 5, the resist underlayer films formed from the compositions of the Examples were superior in solvent resistance and resist pattern rectangularity compared to the resist underlayer films formed from the compositions of the Comparative Examples.

[0179] The composition for forming a resist underlayer film of the present invention can form a film that is excellent in solvent resistance and resist pattern rectangularity. The method for producing a semiconductor substrate of the present invention uses a composition for forming a resist underlayer film that can form a resist underlayer film that is excellent in solvent resistance and resist pattern rectangularity, so that semiconductor substrates can be produced efficiently. Therefore, these compositions can be suitably used in the production of semiconductor devices, etc.

Claims

1. A composition for forming a resist underlayer film, comprising: a polymer having a repeating unit represented by the following formula (1); and a solvent. (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group having a valence of 1+n. １ is a monovalent group having an aromatic ring with 6 to 20 ring members. The aromatic ring has at least one halogen atom. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ar １ are the same or different. １ has at least one group (A) selected from the group consisting of a group represented by the following formula (2-1), a group represented by the following formula (2-2), a group represented by the following formula (2-3), a group represented by the following formula (2-4), a group represented by the following formula (2-5), a group represented by the following formula (2-6), a group represented by the following formula (2-7), and a group represented by the following formula (2-8). (In formulas (2-1) to (2-8), R ７ R is each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. ８ , R ９ , R １０ and R １３ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in formula (2-2). R １１ R is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** is a bond to an atom constituting Cy. However, R １１ is a single bond, R １１ combines with **. * is L １ is a bond to the atoms that make up the molecule.) 2. In the above formula (1), L １ The composition for forming a resist underlayer film according to claim 1, wherein the compound is represented by the following formula (3-1) or (3-2): (In the above formula (3-1), Ar ２ is a 1+n valent group having an aromatic ring with 6 to 20 ring members. s1 is 0 or 1. When multiple s1s are present, the multiple s1s are the same or different from each other. X １ and X ２ are each independently -O-, -NH- or -S-. However, when s1 is 1, X ２ is -O-. １ and X ２ If there are multiple Xs, １ and X ２ are the same or different. n has the same meaning as in formula (1). In formula (3-2), s2 is 0 or 1. X ３ is -O-, -NH- or -S-. However, when s2 is 1, X ３ In the above formulas (3-1) and (3-2), * represents R in the above formula (1). １ is a bond to the carbon atom to which Ar is bonded. ** is a bond to the above group (A). *** is a bond to the Ar １ It is a combination with .) 3. The composition for forming a resist underlayer film according to claim 1 or 2, wherein the content of the repeating unit represented by formula (1) in all repeating units constituting the polymer is 10 mol % or more.

4. The composition for forming a resist underlayer film according to claim 1 or 2, which is a composition for forming an underlayer film of a resist film to be exposed to extreme ultraviolet rays.

5. The composition for forming a resist underlayer film according to claim 1 or 2, wherein the resist underlayer film has a thickness of 20 nm or less.

6. The composition for forming a resist underlayer film according to claim 4, wherein the composition for forming a resist film contains a metal.

7. 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 applying a composition for forming a resist film to 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 formed in the step of applying the composition for forming a resist film to radiation; and a step of developing at least the exposed resist film, wherein the composition for forming a resist underlayer film comprises a polymer having a repeating unit represented by the following formula (1) and a solvent. (In formula (1), R １ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a linking group having a valence of 1+n. １ is a monovalent group having an aromatic ring with 6 to 20 ring members. The aromatic ring has at least one halogen atom. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ar １ are the same or different. １ has at least one group (A) selected from the group consisting of a group represented by the following formula (2-1), a group represented by the following formula (2-2), a group represented by the following formula (2-3), a group represented by the following formula (2-4), a group represented by the following formula (2-5), a group represented by the following formula (2-6), a group represented by the following formula (2-7), and a group represented by the following formula (2-8). (In formulas (2-1) to (2-8), R ７ R is each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. ８ , R ９ , R １０ and R １３ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Cy is a ring structure having 3 to 20 ring members formed together with the two carbon atoms in formula (2-2). R １１ R is a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, or a single bond. １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ** is a bond to an atom constituting Cy. However, R １１ is a single bond, R １１ combines with **. * is L １ is a bond to the atoms that make up the molecule.) 8. The method for manufacturing a semiconductor substrate according to claim 7, wherein said radiation is extreme ultraviolet radiation.

9. The method for producing a semiconductor substrate according to claim 7 or 8, wherein the resist underlayer film has a thickness of 20 nm or less.

10. The method for producing a semiconductor substrate according to claim 7 or 8, wherein the composition for forming a resist film contains a metal.