Semiconductor substrate manufacturing method and composition for forming resist underlayer film

Abstract

The present invention aims to provide a method for manufacturing a semiconductor substrate using a resist underlayer film forming composition that exhibits good pattern rectangularity and excellent storage stability, as well as a resist underlayer film forming composition. A method for manufacturing a semiconductor substrate includes: a step of directly or indirectly coating a resist underlayer film forming composition onto a substrate; a step of coating a resist film forming composition onto a resist underlayer film formed by the resist underlayer film forming composition coating step; a step of exposing the resist film formed by the resist film forming composition coating step to radiation; and a step of developing at least the exposed resist film, wherein the resist underlayer film forming composition contains a polymer, an onium salt that generates at least one polar group selected from the group consisting of carboxyl and hydroxyl groups by radiation or heat, and a solvent.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a semiconductor substrate and a composition for forming a resist underlayer film. [Previous Technology]

[0002] In the manufacture of semiconductor devices, for example, a multilayer resist process has been used. This process involves exposing and developing a resist film deposited on a substrate, such as an organic substrate or a silicon-containing substrate, to form a resist pattern. In this process, the resist substrate is etched using the resist pattern as a mask, and the substrate is then etched using the obtained resist substrate pattern as a mask, thereby forming the desired pattern on the semiconductor substrate.

[0003] In recent years, to further advance the high integration of semiconductor devices, the exposure light used has tended to be shorter wavelengths, from KrF excimer laser (248 nm) and ArF excimer laser (wavelength 193 nm) to extreme ultraviolet (13.5 nm, hereinafter also referred to as "EUV"). Various studies have been conducted on compositions used for forming resist underlayer films under such EUV exposure (see International Publication No. 2013 / 141015). [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2013 / 141015 [Summary of the Invention]

[0005] [Problem to be solved by the invention] In the process of miniaturization progressing to the level where the line width of the resist pattern formed by exposure and development of extreme ultraviolet light is less than 20 nm, the resist underlayer film requires suppressing the downward edge of the pattern at the bottom of the resist film to ensure the rectangularity of the resist pattern.

[0006] This invention is based on the facts described above, and its object is to provide a method for manufacturing a semiconductor substrate using a resist underlayer film composition that can form a resist underlayer film with good pattern rectangularity and excellent storage stability, and a resist underlayer film composition thereof. [Means for Solving the Problem]

[0007] In one embodiment of the present invention, a method for manufacturing a semiconductor substrate is provided, comprising: a step of directly or indirectly coating a resist underlayer film forming composition onto a substrate; a step of coating a resist film forming composition onto a resist underlayer film formed by the resist underlayer film forming composition coating step; a step of exposing the resist film formed by the resist film forming composition coating step to radiation; and a step of developing at least the exposed resist film, wherein the resist underlayer film forming composition comprises a polymer (hereinafter also referred to as "[A] polymer"), an onium salt (hereinafter also referred to as "[B] onium salt") that generates at least one polar group selected from the group consisting of carboxyl and hydroxyl groups by radiation or heat, and a solvent (hereinafter also referred to as "[C] solvent").

[0008] In another embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising a polymer, an onium salt which generates at least one polar group selected from the group consisting of carboxyl and hydroxyl groups by radiation or heat, and a solvent. [Effects of the Invention]

[0009] According to the method for manufacturing this semiconductor substrate, since a resist underlayer film forming composition capable of forming a resist underlayer film with good pattern rectangularity and excellent storage stability is used, a semiconductor substrate with good pattern shape can be efficiently manufactured. According to this resist underlayer film forming composition, it exhibits excellent storage stability and can form a film with good pattern rectangularity. Therefore, these are suitable for use in the manufacture of semiconductor devices that are expected to be further miniaturized in the future.

Implementation Method

[0010] Hereinafter, methods for manufacturing semiconductor substrates and compositions for forming resist underlayer films according to various embodiments of the present invention will be described in detail. Furthermore, combinations of suitable states in the embodiments are also preferred.

[0011] 《Method for Manufacturing a Semiconductor Substrate》 The method for manufacturing a semiconductor substrate includes: a step of directly or indirectly coating a composition for forming a resist underlayer film onto a substrate (hereinafter also referred to as "coating step (I)"); a step of coating a composition for forming a resist film onto a resist underlayer film formed by the coating step of the composition for forming a resist film (hereinafter also referred to as "coating step (II)"); a step of exposing the resist film formed by the coating step of the composition for forming a resist film to radiation (hereinafter also referred to as "exposure step"); and a step of developing at least the exposed resist film (hereinafter also referred to as "development step").

[0012] According to the semiconductor substrate manufacturing method, in the coating step (I), a predetermined resist underlayer film forming composition is used, thereby forming a resist underlayer film with excellent pattern rectangularity, and thus a semiconductor substrate with good pattern shape can be manufactured.

[0013] The semiconductor substrate manufacturing method may, as needed, include a step of directly or indirectly forming a silicon-containing film on the substrate before the coating step (I) (hereinafter also referred to as the "silicon-containing film forming step").

[0014] Hereinafter, the composition for forming the resist underlayer film used in the method for manufacturing the semiconductor substrate and each step including the silicon-containing film formation step as an arbitrary step will be described.

[0015] <Content for Forming Resist Underlayer Film> The composition for forming resist underlayer film (hereinafter also simply referred to as the "composition") contains [A] polymer, [B] onium salt, and [C] solvent. This composition may also contain any component without impairing the effects of the present invention. By containing [A] polymer, [B] onium salt, and [C] solvent, the composition for forming resist underlayer film can improve the preservation stability of the composition and can form a resist underlayer film with excellent pattern rectangularity. While the reason is not certain, it is speculated as follows: The composition for forming resist underlayer film contains an onium salt (i.e., [B] onium salt) as an acid generator; therefore, the acid generated from the onium salt in the resist underlayer film can suppress the lack of acid at the bottom of the resist film in the exposed portion and improve the solubility of the bottom of the resist film in the developing solution to achieve pattern rectangularity. Furthermore, at least one polar group selected from the group consisting of carboxyl and hydroxyl groups in the [B]onium salt is generated by radiation or heat during exposure or baking, thus inhibiting unexpected reactions during storage and improving the storage stability of the composition used to form the resist underlayer film. Moreover, through the polar groups generated by radiation or heat, the [B]onium salt interacts electrostatically and chemically with the [A] polymer, inhibiting excessive diffusion of the [B]onium salt in the resist film and enabling the formation of a rectangular pattern.

[0016] <[A]Polymer> As the [A] polymer, a known polymer used in the formation of the resist underlayer film may be suitably used. The composition may contain one or more [A] polymers. As the [A] polymer, an acrylic polymer is preferred.

[0017] When the polymer in [A] is an acrylic polymer, it is preferred to have a repeating unit (hereinafter also referred to as "repeating unit (1)") represented by the following formula (1). [Formula 1] (in formula (1), R1 is a hydrogen atom or a monovalent hydrocarbon group with 1 to 20 carbon atoms, substituted or unsubstituted; L1 is a single bond or a divalent linker)

[0018] The monovalent hydrocarbon group with 1 to 20 carbons represented by R1 can be, for example, a monovalent chain hydrocarbon group with 1 to 20 carbons, a monovalent alicyclic hydrocarbon group with 3 to 20 carbons, a monovalent aromatic hydrocarbon group with 6 to 20 carbons, or a combination thereof.

[0019] In this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. "Chain hydrocarbon group" refers to a hydrocarbon group that contains only a chain structure and no ring structure, including both straight-chain hydrocarbon groups and branched chain hydrocarbon groups. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure and no aromatic ring structure as its ring structure, including both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (wherein, it is not necessary to contain only an alicyclic structure; a chain structure may also be included in a portion thereof). "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as its ring structure (wherein, it is not necessary to contain only an aromatic ring structure; an alicyclic structure or a chain structure may also be included in a portion thereof).

[0020] As a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, examples include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, dibutyl, and tributyl; alkenyl groups such as vinyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0021] As a monovalent alicyclic hydrocarbon group with 3 to 20 carbon atoms, examples include: cyclopentyl, cyclohexyl and other cycloalkyl groups; cyclopropenyl, cyclopentenyl, cyclohexenyl and other cycloalkenyl groups; norbornyl, adamantyl, tricyclodecyl and other bridged cyclic saturated hydrocarbon groups; norbornyl, tricyclodecenyl and other bridged cyclic unsaturated hydrocarbon groups, etc.

[0022] As monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms, examples include: phenyl, tolyl, naphthyl, anthracene, pyrene, etc.

[0023] When R1 has a substituent, examples of substituents include: monovalent chain hydrocarbons with 1 to 10 carbon atoms; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; alkoxy groups such as methoxy, ethoxy, and propoxy; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl; alkoxycarbonyl groups such as methoxycarbonyloxy and ethoxycarbonyloxy; acetyl, acetyl, propionic, and butyryl; cyano; nitro; and hydroxyl.

[0024] R1 is preferably a hydrogen atom or a methyl group in terms of providing copolymerization of the monotonous repeating unit (1).

[0025] In the formula (1), the divalent linker represented by L1 is preferably a divalent hydrocarbon group, a carbonyl group, an oxygen atom (-O-), an imine group (-NH-) or a combination thereof.

[0026] As a divalent hydrocarbon group in L1, examples include groups formed by removing one hydrogen atom from a monovalent hydrocarbon group with 1 to 20 carbon atoms in R1.

[0027] Wherein, as L1, it is preferably a single bond, an alkyl group formed by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, an aryl group, a carbonyl group, an oxygen atom, an imine group, or a combination thereof formed by removing one hydrogen atom from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and more preferably a single bond, an alkyl group having 1 to 5 carbon atoms, an alkylphenyl group, a carbonyl group, an oxygen atom, an imine group, or a combination thereof.

[0028] As a specific example of the repeating unit (1), the repeating units represented by the following formulas (1-1) to (1-10) can be listed.

[0029] [Chemical 2]

[0030] In the formulas (1-1) to (1-10), R1 has the same meaning as in formula (1). Preferably, it is the repeating unit represented by formulas (1-1), (1-5), and (1-9).

[0031] When the [A] polymer contains repeating units (1), the lower limit of the proportion of the repeating units (1) containing sulfonic acid groups in all repeating units constituting the [A] polymer is preferably 1 mol%, more preferably 5 mol%, further preferably 10 mol%, and especially preferably 20 mol%. The upper limit of the proportion is preferably 100 mol%, more preferably 70 mol%, further preferably 40 mol%, and especially preferably 30 mol%. By setting the proportion of repeating units (1) within the above range, the rectangularity of the pattern can be well achieved. In addition, according to the above range, when an alkaline solution is used as the developer in the development step of the resist film, the resist underlayer film and the resist film can also be removed together.

[0032] [A] The polymer is preferably a repeating unit represented by the following formula (2) (hereinafter also referred to as "repeating unit (2)"). [Chemical 3] (In formula (2), R2 is a hydrogen atom or a monovalent hydrocarbon group with 1 to 20 carbon atoms, substituted or unsubstituted; L2 is a single bond or a divalent linker)

[0033] In formula (2), the monovalent hydrocarbon group with 1 to 20 carbon atoms represented by R2, whether substituted or unsubstituted, can suitably be the group shown as the monovalent hydrocarbon group with 1 to 20 carbon atoms represented by R1 in formula (1). As R2, in terms of providing copolymerization of the monomer of the repeating unit (2), it is preferably a hydrogen atom or a methyl group. When R2 has a substituent, the substituents that R1 in formula (1) may have can be suitably listed as substituents.

[0034] In the formula (2), the divalent linker represented by L2 may suitably be the group shown as the divalent linker represented by L1 in the formula (1). As L2, it is preferably a single bond, an alkyl group formed by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, an alkylene group formed by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, an aryl group formed by removing one hydrogen atom from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, more preferably a single bond, an alkyl group having 1 to 5 carbon atoms, an alkylene group having 5 to 7 carbon atoms, an phenyl group, a carbonyl group, an oxygen atom, or a combination thereof.

[0035] As a specific example of the repeating unit (2), the repeating units represented by the following formulas (2-1) to (2-8) can be listed.

[0036] [Chemical 4]

[0037] In the above formulas (2-1) to (2-8), the meaning of R2 is the same as that of formula (2).

[0038] When the [A] polymer has repeating unit (2), the lower limit of the content ratio of repeating unit (2) in all repeating units constituting the [A] polymer is preferably 10 mol%, more preferably 15 mol%, and even more preferably 20 mol. The upper limit of the content ratio is preferably 99 mol%, more preferably 90 mol%, and even more preferably 80 mol.

[0039] [A] The polymer is preferably a repeating unit represented by the following formula (3) (except for the case of the formula (2)) (hereinafter also referred to as "repeating unit (3)"). [Chemical 5] (In formula (3), R3 is a hydrogen atom or a monovalent hydrocarbon group with 1 to 20 carbon atoms, substituted or unsubstituted; L3 is a single bond or a divalent linker; R4 is a monovalent hydrocarbon group with 1 to 20 carbon atoms, substituted or unsubstituted)

[0040] In formula (3), the substituted or unsubstituted monovalent hydrocarbon groups with 1 to 20 carbon atoms represented by R3 and R4 can be suitably represented by the substituted or unsubstituted monovalent hydrocarbon groups with 1 to 20 carbon atoms represented by R1 in formula (1). As R3, in terms of providing copolymerization of the monomer of the repeating unit (3), it is preferably a hydrogen atom or a methyl group. As R4, it is preferably a monovalent chain hydrocarbon group with 1 to 15 carbon atoms, and more preferably a monovalent branched chain alkyl group with 1 to 10 carbon atoms. When R3 and R4 have substituents, the substituents that R1 in formula (1) may have can be suitably listed as substituents.

[0041] In the formula (3), the divalent linker represented by L3 may suitably be the group shown as the divalent linker represented by L1 in the formula (1). As L3, it is preferably a single bond, an alkyl group formed by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, an extended cycloalkyl group formed by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, more preferably a single bond, an alkyl group having 1 to 5 carbon atoms, an extended cycloalkyl group having 5 to 7 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, and even more preferably a single bond.

[0042] As a specific example of the repeating unit (3), the repeating units represented by the following formulas (3-1) to (3-18) can be listed.

[0043] [Chemical 6]

[0044] In the above formulas (3-1) to (3-18), the meaning of R3 is the same as that in formula (3).

[0045] When the [A] polymer has repeating unit (3), the lower limit of the content ratio of repeating unit (3) in all repeating units constituting the [A] polymer is preferably 20 mol%, more preferably 30 mol%, and even more preferably 35 mol. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol.

[0046] [A] The polymer is preferably a repeating unit represented by the following formula (4) (except for the cases of formula (1), formula (2) and formula (3)) (hereinafter also referred to as "repeating unit (4)"). [Chemical 7] (In formula (4), R5 is a hydrogen atom or a monovalent hydrocarbon group with 1 to 20 carbon atoms, substituted or unsubstituted; L4 is a single bond or a divalent linker; Ar1 ​​is a monovalent group having an aromatic ring with 6 to 20 ring members)

[0047] In this specification, the term "ring member number" refers to the number of atoms that make up the ring. For example, the ring member number of biphenyl is 12, the ring member number of naphthalene is 10, and the ring member number of fluorene is 13.

[0048] In formula (4), the monovalent hydrocarbon group with 1 to 20 carbon atoms represented by R5, whether substituted or unsubstituted, can suitably be the group shown as the monovalent hydrocarbon group with 1 to 20 carbon atoms represented by R1 in formula (1). As R5, in terms of providing copolymerization of the monomer of the repeating unit (4), it is preferably a hydrogen atom or a methyl group. When R5 has a substituent, the substituents that R1 in formula (1) may have can be suitably listed as substituents.

[0049] In the formula (4), the divalent linker represented by L4 may suitably be the group shown as the divalent linker represented by L1 in the formula (1). As L4, it is preferably a single bond, an alkyl group formed by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, an extended cycloalkyl group formed by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, more preferably a single bond, an alkyl group having 1 to 5 carbon atoms, an extended cycloalkyl group having 5 to 7 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, and even more preferably a single bond.

[0050] In the formula (4), the aromatic rings with 6 to 20 ring members in Ar1 can be, for example, aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, indene ring, and pyrene ring; aromatic heterocycles such as pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, and triazine ring, or combinations thereof. The aromatic ring of Ar1 is preferably selected from at least one aromatic hydrocarbon ring in the group consisting of benzene ring, naphthalene ring, anthracene ring, fenestration ring, pyrene ring, fluorene ring, perylene ring, and cardamom ring, more preferably benzene ring, naphthalene ring, or pyrene ring.

[0051] In the formula (4), as a monovalent group having an aromatic ring with 6 to 20 ring members represented by Ar1, it is appropriate to list groups such as those formed by removing one hydrogen atom from the aromatic ring with 6 to 20 ring members in Ar1.

[0052] In the above formula (4), the monovalent group of the aromatic ring having 6 to 20 ring members represented by Ar1 may have substituents. As the substituent in this case, the substituent exemplified when R1 of the above formula (1) has substituents may be used.

[0053] As a specific example of the repeating unit (4), the repeating units represented by the following formulas (4-1) to (4-11) can be listed.

[0054] [Chemical 8]

[0055] In equations (4-1) to (4-11), R5 has the same meaning as in equation (4). Preferably, it refers to the repeating unit represented by equations (4-1) and (4-9).

[0056] When the [A] polymer has repeating unit (4), the lower limit of the content ratio of repeating unit (4) in all repeating units constituting the [A] polymer is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol.

[0057] [A] The polymer may also have repeating units (hereinafter also referred to as "repeating units (5)") comprising at least one of the group consisting of lactone structures, cyclic carbonate structures and sulfonyl lactone structures. Examples of repeating units (5) are the repeating units represented by the following formulas (T-1) to (T-10).

[0058] [Chemical 9]

[0059] In the formula, RL1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. RL2 to RL5 are, independently, hydrogen atoms, alkyl groups with 1 to 4 carbon atoms, cyano groups, trifluoromethyl groups, methoxy groups, methoxycarbonyl groups, hydroxyl groups, hydroxymethyl groups, or dimethylamino groups. RL4 and RL5 may also be divalent alicyclic groups with 3 to 8 carbon atoms that are bonded together with each other. L2 is a single bond or a divalent linker. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0060] As a divalent alicyclic group with 3 to 8 carbon atoms formed by the combination of RL4 and RL5 and together with the bonded carbon atoms, there is no particular limitation if it is a group formed by removing two hydrogen atoms from the same carbon atom of the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon constituting the aforementioned number of carbon atoms. It can be any type of monocyclic hydrocarbon group or polycyclic hydrocarbon group. As a polycyclic hydrocarbon group, it can be any type of bridged alicyclic hydrocarbon group or condensed alicyclic hydrocarbon group, and it can also be any type of saturated hydrocarbon group or unsaturated hydrocarbon group. Furthermore, a condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in the form of multiple alicyclic rings sharing a common edge (the bond between two adjacent carbon atoms).

[0061] Among the monocyclic alicyclic hydrocarbon groups, cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl are preferred as saturated hydrocarbon groups, and cyclopentenidyl, cyclohexenidyl, cycloheptenidyl, cyclooctenidyl, and cyclodecenidyl are preferred as unsaturated hydrocarbon groups. Among the polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclic [2.2.1]heptane-2,2-diyl (norbornene-2,2-diyl), bicyclic [2.2.2]octane-2,2-diyl, and tricyclic [3.3.1.13,7]decane-2,2-diyl (adamantane-2,2-diyl). One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0062] Examples of divalent linking groups represented by L2T include: divalent linear or branched hydrocarbon groups with 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups with 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of -CO-, -O-, -NH- and -S-.

[0063] As repeating units (5), these are preferably repeating units containing lactone structures.

[0064] When the [A] polymer has repeating unit (5), the lower limit of the content ratio of repeating unit (5) in all repeating units constituting the [A] polymer is preferably 3 mol%, more preferably 8 mol%, and even more preferably 10 mol%. The upper limit of the content ratio is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol.

[0065] [A] The polymer may also have repeating units (hereinafter also referred to as "repeating units (6)") containing heteroatom-containing groups (except for repeating units corresponding to repeating units (1) to repeating units (5)). Examples of such heteroatom-containing groups include: hydroxyl, carboxyl, cyano, nitro, sulfonamide, etc. Among these, hydroxyl and carboxyl are preferred, and hydroxyl is even more preferred.

[0066] As a repeating unit (6), for example, repeating units represented by the following formula can be listed.

[0067] [Chemical 10]

[0068] In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0069] When the [A] polymer has repeating unit (6), the lower limit of the content ratio of repeating unit (6) in all repeating units constituting the [A] polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. In addition, the upper limit of the content ratio is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol.

[0070] Other repeating units may include repeating units used in polymers of resist compositions that incorporate repeating units of the structure of [B]onium salts, as described later.

[0071] The lower limit of the weight average molecular weight of polymer [A] is preferably 500, more preferably 1000, further preferably 1500, and particularly preferably 2000. The upper limit of the molecular weight is preferably 10000, more preferably 9000, further preferably 8000, and particularly preferably 7000. Furthermore, the method for determining the weight average molecular weight is based on the description in the examples.

[0072] As a lower limit for the content of polymer [A] in the composition for forming the resist underlayer film, it is preferably 1% by mass, more preferably 2% by mass, further preferably 3% by mass, and especially preferably 4% by mass, in the total mass of polymer [A], onion salt, and solvent [C]. As an upper limit for the content, it is preferably 20% by mass, more preferably 15% by mass, further preferably 12% by mass, and especially preferably 10% by mass, in the total mass of polymer [A] and solvent [C].

[0073] The lower limit of the content of polymer [A] in the composition for forming the resist underlayer film, other than solvent [C], is preferably 10% by mass, more preferably 20% by mass, further preferably 30% by mass, and especially preferably 40% by mass. The upper limit of the content is preferably 90% by mass, more preferably 80% by mass, and further preferably 70% by mass.

[0074] [[A] Polymer Synthesis Method] [A] Polymer can be synthesized by free radical polymerization, ionic polymerization, condensation polymerization, addition polymerization, addition condensation, etc., depending on the type of monomer. For example, in the case of synthesizing [A] polymer by free radical polymerization, it can be synthesized by using a free radical polymerization initiator or the like to polymerize the monomers providing each repeating unit in a suitable solvent.

[0075] Examples of free radical polymerization initiators include: azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl 2,2'-azobisisobutyrate (also known as dimethyl 2,2'-azobis(2-methylpropionic acid) ester), and other azo-based free radical initiators; peroxide-based free radical initiators such as benzoyl peroxide, tert-butyl hydroperoxide, and cumene hydroperoxide. These free radical initiators can be used alone or in combination.

[0076] The solvents used in the polymerization may suitably be the [C] solvents described later. These solvents used in the polymerization may be used alone or in combination of two or more.

[0077] The reaction temperature in the polymerization is typically 40°C to 150°C, preferably 50°C to 120°C. The reaction time is typically 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0078] <[B]onium salt> A [B]onium salt is a compound having an anionic and a cationic moiety, and having at least one polar group selected from the group consisting of carboxyl and hydroxyl groups generated by radiation or heat. Although a polar group can be generated by radiation or heat in one or both of the anionic and cationic moieties, it is preferred that the polar group be generated by radiation or heat in at least the anionic moiety of the [B]onium salt. The hydroxyl group can be either an alcoholic hydroxyl group or a phenolic hydroxyl group. The [B]onium salt can also function as a component that generates an acid by the action of heat or radiation. A [B]onium salt can be used alone or in combination of two or more.

[0079] As a [B]onium salt, examples include: strontium salt, tetrahydrothiophene onium salt, ferrophosphate salt, phosphonium salt, diazonium salt, pyridinium salt, etc. Among these, strontium salt or ferrophosphate salt is preferred.

[0080] [B] The anionic portion of the onium salt preferably has a sulfonate anion. More preferably, at least one of the groups consisting of fluorine atoms and fluorinated hydrocarbon groups is bonded to the carbon atom bonded to the sulfonate anion. With these structures, sufficient strong acid can be supplied to the bottom of the resist film, which can suppress the drooping of the pattern and further improve the rectangularity of the pattern.

[0081] The carboxyl or hydroxyl group, which is a polar group, preferably has a structure protected by a protecting group. The carboxyl or hydroxyl group is generated by deprotection through radiation or heat. There are no particular limitations on the protecting structure. In the case of a carboxyl group, ester structures can be listed; in the case of an alcoholic hydroxyl group, acetal structures, ester structures, (silyl) ether structures can be listed; and in the case of a phenolic hydroxyl group, ether structures can be listed, etc.

[0082] [B]The anionic portion of the onium salt preferably contains a ring structure. As a ring structure, a polycyclic structure is preferred, and a norbornene structure is even more preferred.

[0083] The [B]onium salt preferably has the structure represented by the following formula (c). It can be considered that by having the following structure, the diffusion length of the acid generated in the photoresist film during the exposure step of the photoresist film is appropriately shortened, and as a result, a photoresist underlayer film with excellent pattern rectangularity can be formed.

[0084] [Chemical 11]

[0085] In formula (c), Rp1 is a monovalent organic group with 1 to 40 carbon atoms. Rp2 is a divalent linker. Rp3 and Rp4 are independently hydrogen atoms, fluorine atoms, monovalent hydrocarbon groups with 1 to 20 carbon atoms, or monovalent fluorinated hydrocarbon groups with 1 to 20 carbon atoms, respectively. Rp5 and Rp6 are independently fluorine atoms or monovalent fluorinated hydrocarbon groups with 1 to 20 carbon atoms, respectively. np1 is an integer from 0 to 10. np2 is an integer from 0 to 10. np3 is an integer from 1 to 10. When np1 is 2 or more, multiple Rp2s may be the same or different. When np2 is 2 or more, multiple Rp3s may be the same or different, and multiple Rp4s may be the same or different. When np3 is 2 or more, multiple Rp5s may be the same or different, and multiple Rp6s may be the same or different. X+ is a monovalent radiosensitive linear ononium cation.

[0086] The monovalent organic group with 1 to 40 carbon atoms represented by Rp1 is not particularly limited and can be any of a chain structure, a cyclic structure, or a combination thereof. As the chain structure, examples include chain hydrocarbon groups that are saturated or unsaturated, straight-chain or branched. As the cyclic structure, examples include cyclic hydrocarbon groups that are alicyclic, aromatic, or heterocyclic. Preferably, the monovalent organic group is a monovalent chain hydrocarbon group with 1 to 20 carbon atoms that is substituted or unsubstituted, a monovalent alicyclic hydrocarbon group with 3 to 20 carbon atoms that is substituted or unsubstituted, a monovalent aromatic hydrocarbon group with 6 to 20 carbon atoms that is substituted or unsubstituted, or a combination thereof. Additionally, examples include: groups formed by substituting some or all of the hydrogen atoms in a group having a chain structure or a group having a cyclic structure with substituents; groups containing CO, CS, O, S, SO2, or NR', or a combination of two or more of these, between the carbon atoms of such groups. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0087] Examples of substituents that replace part or all of the hydrogen atoms in the organic group include: halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acetoyl groups, acetoyl groups, or groups formed by replacing the hydrogen atoms of these groups with halogen atoms; and side oxygen groups (=O).

[0088] As the monovalent chain hydrocarbon group having 1 to 20 carbon atoms, examples include straight-chain or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, or straight-chain or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms.

[0089] Examples of alicyclic hydrocarbon groups with 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclic decyl, and tetracyclic dodecyl. Furthermore, a bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0090] As the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, examples include: aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracene; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0091] Examples of heterocyclic cyclic hydrocarbon groups include groups formed by removing one hydrogen atom from an aromatic heterocyclic structure and groups formed by removing one hydrogen atom from an alicyclic heterocyclic structure. Aromatic structures with five-membered rings that possess aromaticity by introducing heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0092] Examples of the aromatic heterocyclic structures include: aromatic heterocyclic structures containing oxygen atoms such as furan, pyran, benzofuran, and benzopyran; aromatic heterocyclic structures containing nitrogen atoms such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; aromatic heterocyclic structures containing sulfur atoms such as thiophene; and aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0093] Examples of the alicyclic heterocyclic structures include: oxygen-containing alicyclic heterocyclic structures such as oxacyclopropane, tetrahydrofuran, tetrahydropyran, dioxane, and dioxane; nitrogen-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; sulfur-containing alicyclic heterocyclic structures such as thietane, thietane, and thiane; and alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiocyclopentane, and 1,3-oxathiocyclopentane.

[0094] Examples of cyclic structures include: lactone structures, cyclic carbonate structures, sulfonyl lactone structures, and structures containing cyclic acetals. Examples of such structures include those represented by formulas (H-1) to (H-11).

[0095] [Chemical 12]

[0096] In the formula, m is an integer from 1 to 3.

[0097] Two or more structures represented by formulas (H-1) to (H-11) may form a fused ring structure or a spiral ring structure with each other. Alternatively, the structures represented by formulas (H-1) to (H-11) may form a fused ring structure or a spiral ring structure with other ring structures.

[0098] Examples of divalent linking groups represented by Rp2 include: carbonyl, ether, carbonyloxy, thioether, thiocarbonyl, sulfonyl, divalent hydrocarbon, or combinations thereof. A cyclic structure as shown in Rp1 may also be present between these groups.

[0099] As the monovalent hydrocarbon group representing 1 to 20 carbon atoms, Rp3 and Rp4 can be alkyl groups having 1 to 20 carbon atoms, for example. As the monovalent fluorinated hydrocarbon group representing 1 to 20 carbon atoms, Rp3 and Rp4 can be fluorinated alkyl groups having 1 to 20 carbon atoms, for example. Rp3 and Rp4 are preferably hydrogen atoms, fluorine atoms, and fluorinated alkyl groups, more preferably fluorine atoms and perfluoroalkyl groups, and even more preferably fluorine atoms and trifluoromethyl groups.

[0100] As Rp5 and Rp6, the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms can be exemplified by fluorinated alkyl groups having 1 to 20 carbon atoms. Rp5 and Rp6 are preferably fluorine atoms and fluorinated alkyl groups, more preferably fluorine atoms and perfluoroalkyl groups, even more preferably fluorine atoms and trifluoromethyl groups, and especially preferably fluorine atoms.

[0101] As np1, it is preferably an integer from 0 to 5, more preferably an integer from 0 to 3, even more preferably an integer from 0 to 2, and especially preferably 0 and 1.

[0102] As np2, it is preferably an integer from 0 to 5, more preferably an integer from 0 to 2, and even more preferably 0 or 1, and especially preferably 0.

[0103] As np3, it is preferably an integer from 1 to 5, more preferably an integer from 1 to 4, even more preferably an integer from 1 to 3, and especially preferably 1 and 2.

[0104] The monovalent radiosensitive linear ononium cation represented by X+ is a cation that decomposes upon exposure to light. In the exposure section, the proton generated by the decomposition of this photodegradable ononium cation reacts with a sulfonate anion to produce sulfonic acid. Examples of the monovalent radiosensitive linear ononium cation represented by X+ include: cations represented by the following formula (ca) (hereinafter also referred to as "cation (ca)"), cations represented by the following formula (cb) (hereinafter also referred to as "cation (cb)"), cations represented by the following formula (cc) (hereinafter also referred to as "cation (cc)"), etc.

[0105] [Chemistry 13]

[0106] In the formula (ca), RC3, RC4, and RC5 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 having 6 to 12 carbon atoms, a -OSO2-RCC1 group or a -SO2-RCC2 group, or represent a ring structure formed by the combination of two or more of these groups. RCC1 and RCC2 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. c1, c2, and c3 are each independently an integer from 0 to 5. When there are multiple RC3 to RC5 and multiple RCC1 and RCC2, the multiple RC3 to RC5 and multiple RCC1 and RCC2 may be the same or different.

[0107] In the formula (cb), RC6 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acetyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. c4 is an integer from 0 to 7. When there are multiple RC6 groups, the multiple RC6 groups may be the same or different. In addition, the multiple RC6 groups may also represent a ring structure formed by their mutual bonding. RC7 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. c5 is an integer from 0 to 6. When there are multiple RC7 groups, the multiple RC7 groups may be the same or different. In addition, the multiple RC7 groups may also represent a ring structure formed by their mutual bonding. nc2 is an integer from 0 to 3. RC8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. nc1 is an integer from 0 to 2.

[0108] In the formula (cc), RC9 and RC10 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 12 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups having 6 to 12 carbon atoms, -OSO2-RCC3 or -SO2-RCC4, or represent a ring structure formed by the combination of two or more of these groups. RCC3 and RCC4 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 12 carbon atoms, substituted or unsubstituted alicyclic hydrocarbon groups having 5 to 25 carbon atoms, or substituted or unsubstituted aromatic hydrocarbon groups having 6 to 12 carbon atoms. c6 and c7 are independently integers from 0 to 5. When there are multiple RC9, RC10, RCC3 and RCC4, the multiple RC9, RC10, RCC3 and RCC4 may be the same or different.

[0109] The unsubstituted linear alkyl group represented by RC3, RC4, RC5, RC6, RC7, RC9 and RC10 can be exemplified by, for example, methyl, ethyl, n-propyl, n-butyl and the like.

[0110] As unsubstituted branched alkyl groups represented by RC3, RC4, RC5, RC6, RC7, RC9 and RC10, examples include: isopropyl, isobutyl, dibutyl, tributyl, etc.

[0111] The unsubstituted aromatic hydrocarbon groups represented by RC3, RC4, RC5, RC9 and RC10 can be exemplified by, for example: aryl groups such as phenyl, tolyl, xylyl, mesitylelel, naphthyl; and arylalkyl groups such as benzyl and phenethyl.

[0112] The unsubstituted aromatic hydrocarbon groups represented by RC6 and RC7 can be exemplified by, for example, phenyl, tolyl, benzyl, etc.

[0113] As a divalent organic group represented by RC8, examples include: a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (a) having a divalent heteroatom at the end of the carbon-carbon bond or the side of the bond of the hydrocarbon group, and a group obtained by removing one hydrogen atom from a group obtained by substituting part or all of the hydrogen atoms of the hydrocarbon group and the group (a) with a monovalent heteroatom.

[0114] As the monovalent hydrocarbon group having 1 to 20 carbon atoms, examples may be the same as those exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by Rp1 in formula (c).

[0115] Examples of divalent heteroatom-containing groups include: -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and groups formed by combining two or more of these. R' is a hydrogen atom or a monovalent hydrocarbon group.

[0116] As the monovalent heteroatom-containing group, examples include: halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; hydroxyl group; carboxyl group; cyano group; amino group; hydrogen sulfide group (-SH), etc.

[0117] Examples of substituents that can replace hydrogen atoms in alkyl and aromatic hydrocarbon groups include: halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl, carboxyl, cyano, nitro, alkoxy, alkoxycarbonyl, alkoxycarbonyloxy, acetyl, and acetyloxy groups. Among these, halogen atoms are preferred, and fluorine atoms are even more preferred.

[0118] Preferably, at least one of Rp1 to Rp6 in formula (c), RC3 to RC5 in formula (ca), RC6 to RC7 in formula (cb), and RC9 to RC10 in formula (cc) has a protective structure that generates a carboxyl or hydroxyl group by deprotection through radiation or heat, and more preferably, at least one of Rp1 to Rp6 in formula (c) has a protective structure that generates a carboxyl or hydroxyl group by deprotection through radiation or heat.

[0119] As the [B]onium salt represented by formula (c), examples include compounds represented by formulas (c1) to (c21) (hereinafter also referred to as "compound (c1) to compound (c21)"). In the formula, "Bu" represents "n-butyl".

[0120] [Chemistry 14]

[0121] [Chemistry 15]

[0122] [Chemistry 16]

[0123] [Chemistry 17]

[0124] The lower limit of the content of [B]onium salt in the composition for forming the resist underlayer film is preferably 1 part by mass, more preferably 3 parts by mass, and even more preferably 5 parts by mass relative to 100 parts by mass of [A] polymer. The upper limit of the content is preferably 50 parts by mass, more preferably 45 parts by mass, and even more preferably 40 parts by mass.

[0125] <[C] Solvent> There are no particular limitations on whether the [C] solvent can dissolve or disperse the [A] polymer, [B] onium salt and any other components as required.

[0126] As a solvent for [C], examples include: hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, etc. A solvent for [C] may be used alone or in combination of two or more.

[0127] As hydrocarbon solvents, examples include: aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0128] As an ester-based solvent, examples include: carbonate solvents such as diethyl carbonate; monoacetic acid ester solvents such as methyl acetate and ethyl acetate; lactone solvents such as γ-butyrolactone; polyol partial ether carboxylic acid ester solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate; lactate solvents such as methyl lactate and ethyl lactate, etc.

[0129] As an alcohol-based solvent, examples include: mono-alcohol solvents such as methanol, ethanol, n-propanol, and 4-methyl-2-pentanol; poly-alcohol solvents such as ethylene glycol and 1,2-propanediol.

[0130] As a ketone solvent, examples include: chain ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and 2-heptanone; cyclic ketone solvents such as cyclohexanone, etc.

[0131] As an ether-based solvent, examples include: chain ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran, and other polyol ether solvents; diethylene glycol monomethyl ether, propylene glycol monomethyl ether, and other polyol partial ether solvents.

[0132] Examples of nitrogen-containing solvents include: chain-like nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0133] The solvent for [C] is preferably an alcohol-based solvent, an ether-based solvent, or an ester-based solvent, more preferably a monool-based solvent, a polyol partially ether-based solvent, or a polyol partially ether carboxylic acid ester-based solvent, and even more preferably 4-methyl-2-pentanol, propylene glycol monomethyl ether, or propylene glycol monomethyl ether acetate.

[0134] The lower limit of the content of the [C] solvent in the composition for forming the resist underlayer film is preferably 50% by mass, more preferably 60% by mass, and even more preferably 70% by mass. The upper limit of the content is preferably 99.9% by mass, more preferably 99% by mass, and even more preferably 95% by mass.

[0135] [Any Components] The composition for forming the resist underlayer film may also contain any components without impairing the effects of the present invention. Examples of arbitrary components include: crosslinking agents, acid diffusion control agents, surfactants, etc. Any component may be used alone or in combination of two or more.

[0136] ([D] Crosslinking Agent) The type of [D] crosslinking agent is not particularly limited, and any known crosslinking agent can be freely selected. Preferably, at least one selected from polyfunctional (meth)acrylates, compounds containing cyclic ethers, glycoureas, diisocyanates, melamines, benzoguanamines, polyphenols, polyfunctional thiols, polysulfide compounds, and thioether compounds is used as the crosslinking agent. By including the [D] crosslinking agent in the composition, electrostatic and chemical interactions (mainly crosslinking or hydrogen bonding) with the [B]onium salt are generated, which can more effectively suppress the excessive diffusion of acid generated from the [B]onium salt into the resist film.

[0137] As a polyfunctional (meth)acrylate, there is no particular limitation if it is a compound having two or more (meth)acrylic groups. Examples include: polyfunctional (meth)acrylates obtained by reacting an aliphatic polyhydroxy compound with (meth)acrylic acid, polyfunctional (meth)acrylates modified with caprolactone, polyfunctional (meth)acrylates modified with epoxide, polyfunctional aminocarbamate (meth)acrylates obtained by reacting a hydroxyl-containing (meth)acrylate with a polyfunctional isocyanate, and polyfunctional (meth)acrylates with carboxyl groups obtained by reacting a hydroxyl-containing (meth)acrylate with an acid anhydride.

[0138] Specifically, examples include: trimethylolpropane tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerol tri(meth)acrylate, tri(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, etc.

[0139] Examples of compounds containing cyclic ethers include: 1,6-hexanediol diglycidyl ether, 3',4'-epoxycyclohexene methyl-3',4'-epoxycyclohexene carboxylate, vinylcyclohexene monooxide 1,2-epoxy-4-vinylcyclohexene, 1,2:8,9-diepoxylimonene, and other oxetane-containing compounds; 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, xylyldioxetane, 3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane, and other oxetane-containing compounds. These compounds containing cyclic ethers can be used alone or in combination of two or more.

[0140] As a glycourea class, examples include: tetrahydroxymethylglycourea, tetramethoxyglycourea, tetramethoxymethylglycourea, compounds formed by methoxymethylation of one to four hydroxymethyl groups of tetrahydroxymethylglycourea or mixtures thereof, compounds formed by acetoxymethylation of one to four hydroxymethyl groups of tetrahydroxymethylglycourea, or glycidylglycourea classes, etc.

[0141] Examples of glycidylglycerols include: 1-glycidylglycerol, 1,3-diglycidylglycerol, 1,4-diglycidylglycerol, 1,6-diglycidylglycerol, 1,3,4-triglycidylglycerol, 1,3,4,6-tetraglycidylglycerol, 1-glycidyl-3a-methylglycerol, 1-glycidyl-6a-methylglycerol, 1,3-diglycidyl-3a-methylglycerol, 1,4-diglycidyl-3a-methylglycerol, 1,6-diglycidyl-3a-methylglycerol, 1,3,4-triglycidyl-3a-methylglycerol, 1,3,4-triglycidyl-6a-methylglycerol, 1,3,4,6-tetraglycidyl-3a-methylglycerol, 1-glycidyl-3a,6 α-Dimethylglycourea, 1,3-diglycidyl-3a,6a-dimethylglycourea, 1,4-diglycidyl-3a,6a-dimethylglycourea, 1,6-diglycidyl-3a,6a-dimethylglycourea, 1,3,4-triglycidyl-3a,6a-dimethylglycourea, 1,3,4,6-tetraglycidyl-3a,6a-dimethylglycourea, 1-glycidyl Examples of glycoureas include 1,3-diglycidyl-3a,6a-diphenylglycourea, 1,4-diglycidyl-3a,6a-diphenylglycourea, 1,6-diglycidyl-3a,6a-diphenylglycourea, 1,3,4-triglycidyl-3a,6a-diphenylglycourea, and 1,3,4,6-tetraglycidyl-3a,6a-diphenylglycourea. These glycoureas can be used alone or in combination of two or more.

[0142] As diisocyanates, examples include: 2,3-toluene diisocyanate, 2,4-toluene diisocyanate, 3,4-toluene diisocyanate, 3,5-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, etc.

[0143] Examples of melamine derivatives include: melamine, monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine, monobutylol melamine, dibutylol melamine, tributylol melamine, tetrabutylol melamine, pentamethylol melamine, hexamethylol melamine, or alkylated derivatives of these methylol melamine or butylol melamine derivatives. These melamine derivatives can be used alone or in combination of two or more.

[0144] Examples of benzoguanidines include: benzoguanidines modified with four alkoxymethyl groups (alkoxyhydroxymethyl groups) (tetraalkoxymethyl benzoguanidines), such as tetramethoxymethyl benzoguanidine; benzoguanidines modified with a total of four alkoxymethyl groups (especially methoxymethyl groups) and hydroxymethyl groups; benzoguanidines modified with three or fewer alkoxymethyl groups (especially methoxymethyl groups); and benzoguanidines modified with three or fewer alkoxymethyl groups (especially methoxymethyl groups) and hydroxymethyl groups. These benzoguanidines can be used alone or in combination of two or more.

[0145] Examples of polynuclear phenols include: dinuclear phenols such as 4,4'-biphenyldiol, 4,4'-methylenebisphenol, 4,4'-ethylidenebisphenol, and bisphenol A; trinuclear phenols such as 4,4',4''-epimethylenetriphenol, 4,4'-(1-(4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl)ethylidene)bisphenol, and 4,4'-(1-(4-(1-(4-hydroxy-3,5-bis(methoxymethyl)phenyl)-1-methylethyl)phenyl)ethylidene)bis(2,6-bis(methoxymethyl)phenol); and polyphenols such as phenolic varnishes. These polynuclear phenols can be used alone or in combination of two or more.

[0146] A polyfunctional thiol compound is a compound having two or more thiol groups in one molecule. Examples of such compounds include: 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 2,3-dimercapto-1-propanol, dithioerythritol, 2,3-dimercaptosuccinic acid, and 1,2-benzenediol. 1,2-Phenylacetylene, 1,3-Phenylacetylene, 1,3-Phenylacetylene, 1,4-Phenylacetylene, 3,4-Dimercaptotoluene, 4-Chloro-1,3-Phenylacetylene, 2,4,6-Trimethyl-1,3-Phenylacetylene, 4,4'-Thiodiphenol, 2-Hexylamino-4,6-Dimercapto-1,3,5-Triazine, 2-Diethylamino-4,6-Dimercapto-1,3,5-Triazine, 2-Cyclohexylamino-4,6-Dimercapto-1,3, Compounds containing two thiol groups, such as 5-triazine, 2-di-n-butylamino-4,6-dimercapto-1,3,5-triazine, ethylene glycol bis(3-mercaptopropionate), butanediol dimercaptoacetate, ethylene glycol dimercaptoacetate, 2,5-dimercapto-1,3,4-thiadiazole, 2,2'-(ethylenedithio)diethanethiol, and 2,2-bis(2-hydroxy-3-mercaptopropoxyphenylpropane); 1,2,6-hexanetriol trimercaptoacetate, 1,3,5-trithiotrimer Compounds containing three thiol groups, such as cyanic acid, trimethylolpropane tris(3-mercaptopropionate), and trimethylolpropane trimercaptoacetate; and compounds containing four or more thiol groups, such as pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(2-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyrooxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. These polyfunctional thiols can be used alone or in combination of two or more.

[0147] When the composition for forming the resist underlayer film contains a [D] crosslinking agent, the lower limit of the content of the [D] crosslinking agent is preferably 1 part by mass, more preferably 2 parts by mass, and even more preferably 3 parts by mass relative to 100 parts by mass of the [A] polymer. The upper limit of the content is preferably 60 parts by mass, more preferably 50 parts by mass, and even more preferably 40 parts by mass.

[0148] ([E] Acid Diffusion Control Agent) [E] Acid diffusion control agent is a component that captures acids and cations. [E] Acid diffusion control agent can be used alone or in combination of two or more.

[0149] The aforementioned [E] acid diffusion control agent can be divided into compounds that are radioactive and compounds that are not radioactive.

[0150] The non-radioactive compound is preferably a basic compound. Examples of such basic compounds include hydroxide compounds, carboxylic acid ester compounds, amine compounds, imine compounds, amide compounds, etc. More specifically, examples include primary to tertiary aliphatic amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, nitrogen-containing compounds having a carbamate group, amide compounds, amide imine compounds, etc., among which nitrogen-containing compounds having a carbamate group are preferred.

[0151] In addition, the alkaline compound may also be Troger's base; hindered amines such as diazabicycloundecene (DBU) and diazabicyclononene (DBM); ionic quenchers such as tetrabutylammonium hydroxide (TBAH) and tetrabutylammonium lactate.

[0152] Examples of the primary aliphatic amines include: ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, dibutylamine, tert-butylamine, pentylamine, tert-pentylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, tetraethylenepentamine, etc.

[0153] Examples of the secondary aliphatic amines include: dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-dibutylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, di-dodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, N,N-dimethyltetraethylenepentamine, etc.

[0154] Examples of the tertiary aliphatic amines include: trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-dibutylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tri-dodecylamine, tricerylamine, N,N,N',N'-tetramethylmethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyltetraethylenepentamine, etc.

[0155] Examples of the aromatic amines and heterocyclic amines include: aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, N,N-dimethyltoluidine, and other aniline derivatives; diphenyl(p-toluyl)amine; methyldiphenylamine; triphenylamine; phenylenediamine; naphthylamine; diaminonaphthalene; pyrrole derivatives such as pyrrole, 2H-pyrrole, 1-methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole; oxazole derivatives such as oxazole and isoxazole; thiazole derivatives such as thiazole and isothiazole; imidazole derivatives such as imidazole, 4-methylimidazole, and 4-methyl-2-phenylimidazole; pyrazole derivatives; furazolidone derivatives; pyrroline derivatives such as pyrroline and 2-methyl-1-pyrroline; pyrrolidine derivatives such as pyrrolidine, N-methylpyrrolidine, pyrrolidone, and N-methylpyrrolidone; imidazoline derivatives. Compounds; imidazoline derivatives; pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 4-pyrrolididine, 2-(1-ethylpropyl)pyridine, aminopyridine, dimethylaminopyridine, etc.; pyridazine derivatives; pyrimidine derivatives; pyrazine derivatives; pyrazine derivatives; pyrazoline derivatives; pyrazole Pyridine derivatives; piperidine derivatives; piperazine derivatives; morpholine derivatives; indole derivatives; isoindole derivatives; 1H-indazole derivatives; indoleline derivatives; quinoline, 3-quinoline carboxynitrile, and other quinoline derivatives; isoquinoline derivatives; phosphonoline derivatives; quinazoline derivatives; quinoxaline derivatives; phthalazine derivatives; purine derivatives; pteridine derivatives; carbazole derivatives; phenidine derivatives; acridine derivatives; phenidine derivatives; 1,10-phenidine derivatives; adenine derivatives; adenosine derivatives; guanine derivatives; guanosine derivatives; uracil derivatives; uridine derivatives, etc.

[0156] Examples of nitrogen-containing compounds having a carboxyl group include: aminobenzoic acid; indole carboxylic acid; nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycine-leucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, methoxyalanine, and other amino acid derivatives.

[0157] Examples of nitrogen-containing compounds having a sulfonic group include 3-pyridine sulfonic acid and p-toluenesulfonic acid pyridinium.

[0158] Examples of nitrogen-containing compounds having hydroxyl groups, nitrogen-containing compounds having hydroxyphenyl groups, and alcoholic nitrogen-containing compounds include: 2-hydroxypyridine, aminocresol, 2,4-quinolinediol, 3-indole methanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine, triisopropanolamine, 2,2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4- Amino-1-butanol, 4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidone, 3-piperidinyl-1,2-propanediol, 3-pyrrolidinyl-1,2-propanediol, 8-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidone ethanol, 1-aziridinyl ethanol, N-(2-hydroxyethyl)phthalimide, N-(2-hydroxyethyl)isonicotinamide, etc.

[0159] Examples of nitrogen-containing compounds having carbamate groups include: N-(tert-butoxycarbonyl)-L-propanic acid, methyl N-(tert-butoxycarbonyl)-L-propanate, (S)-(-)-2-(tert-butoxycarbonylamino)-3-cyclohexyl-1-propanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-methyl-1-butanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-phenylpropanol, and (S)-(-)-2-(tert-butoxycarbonylamino)-3-phenylpropanol. , (R)-(+)-2-(tert-butoxycarbonylamino)-3-phenyl-1-propanol, (S)-(-)-2-(tert-butoxycarbonylamino)-3-phenyl-1-propanol, (R)-(+)-2-(tert-butoxycarbonylamino)-1-propanol, (S)-(-)-2-(tert-butoxycarbonylamino)-1-propanol, N-(tert-butoxycarbonyl)-L-aspartic acid 4-benzyl ester, N-(tert-butoxycarbonyl)-O-benzyl-L-threonine, (R)-(+)-1-(tert-butoxycarbonyl)-2-tert-butoxycarbonyl)-3-phenyl-1-propanol Butyl-3-methyl-4-imidazolidineone, (S)-(-)-1-(tert-butoxycarbonyl)-2-tert-butyl-3-methyl-4-imidazolidineone, N-(tert-butoxycarbonyl)-3-cyclohexyl-L-propanediol methyl ester, N-(tert-butoxycarbonyl)-L-cysteine ​​methyl ester, N-(tert-butoxycarbonyl)ethanolamine, N-(tert-butoxycarbonyl)ethylenediamine, N-(tert-butoxycarbonyl)-D-glucosamine, Nα-(tert-butoxycarbonyl)-L-glutamine, 1-(tert-butoxycarbonyl)imidazolium, N-(tert-butoxycarbonyl)imidazolium N-(tert-butoxycarbonyl)-L-isoleucine, N-(tert-butoxycarbonyl)-L-isoleucine methyl ester, N-(tert-butoxycarbonyl)-L-leucine alcohol, Nα-(tert-butoxycarbonyl)-L-lysine, N-(tert-butoxycarbonyl)-L-methionine, N-(tert-butoxycarbonyl)-3-(2-naphthyl)-L-alanine, N-(tert-butoxycarbonyl)-L-phenylalanine, N-(tert-butoxycarbonyl)-L-phenylalanine methyl ester, N-(tert-butoxycarbonyl)-D-proline aldehyde (N-(tert-butoxycarbonyl)-L-isoleucine)(carbonyl)-D-prolinal), N-(tert-butoxycarbonyl)-L-proline, N-(tert-butoxycarbonyl)-L-proline-N'-methoxy-N'-methylamide, N-(tert-butoxycarbonyl)-1H-pyrazole-1-carboxymidane, (S)-(-)-1-(tert-butoxycarbonyl)-2-pyrrolidinemethanol, (R)-(+)-1-(tert-butoxycarbonyl)-2-pyrrolidinemethanol, 1-(tert-butoxycarbonyl)3-[4-(1- [Pyrroleyl]-L-alanine, N-(tert-butoxycarbonyl)-L-serine, N-(tert-butoxycarbonyl)-L-serine methyl ester, N-(tert-butoxycarbonyl)-L-threonine, N-(tert-butoxycarbonyl)-p-toluenesulfonamide, N-(tert-butoxycarbonyl)-S-triphenylmethyl-L-cysteine, Nα-(tert-butoxycarbonyl)-L-tryptophan, N-(tert-butoxycarbonyl)-L-tyrosine, N-(tert-butoxycarbonyl)-L-tyrosine methyl ester, N-(tert-butoxycarbonyl)-L-valine, N-(tert-butoxycarbonyl)-L-valine methyl ester, N-(tert-butoxycarbonyl)-L-valine alcohol, N-(3-hydroxypropyl)carbamate tert-butyl ester, N-(6-aminohexyl)carbamate tert-butyl ester, carbamate tert-butyl ester, hydrazine carbamate tert-butyl ester, N-(benzyloxy)carbamate tert-butyl ester, 4-benzyl-1-piperazinic acid tert-butyl ester, (1S,4S)-(-)-2,5-diazabicyclo[2.2.1]heptane- 2-Carboxylic acid tert-butyl ester, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester, (S)-(-)-4-methoxy-2,2-dimethyl-3-oxazolidinecarboxylic acid tert-butyl ester, [R-(R*,S*)]-N-[2-hydroxy-2-(3-hydroxyphenyl)-1-methylethyl]carbamate tert-butyl ester, 4-oxo-1-piperidinecarboxylic acid tert-butyl ester, 1-pyrrolic carboxylic acid tert-butyl ester, 1-pyrrolic carboxylic acid tert-butyl ester, (tetrahydro-2-oxo-3-furanyl)carbamate tert-butyl ester, etc.

[0160] Examples of the acetamide compounds include: methylamine, N-methylmethylamine, N,N-dimethylmethylamine, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzylamine, 1-cyclohexylpyrrolidone, etc.

[0161] Examples of the acetimine compounds include phthalimide, succinimide, and maleimide.

[0162] In addition, the radioactive compounds can be divided into compounds that decompose and lose their acid diffusion control ability by radiation (radiodecomposition compounds) and compounds that are generated by radiation and gain acid diffusion control ability (radiogenerating compounds).

[0163] The radiodegradable compound is preferably a sulfonate or carboxylate of a radiodegradable cation. The sulfonic acid in the sulfonate is preferably a weak acid, more preferably a sulfonic acid having a hydrocarbon group with 1 to 20 carbon atoms and the hydrocarbon group being fluorine-free. Examples of such sulfonic acids include alkyl sulfonic acids, benzene sulfonic acids, and 10-camphor sulfonic acid. The carboxylic acid in the carboxylate is preferably a weak acid, more preferably a carboxylic acid with 1 to 20 carbon atoms. Examples of such carboxylic acids include formic acid, acetic acid, propionic acid, tartaric acid, succinic acid, cyclohexylcarboxylic acid, benzoic acid, and salicylic acid. The radiodegradable cation in the carboxylate is preferably an ononium cation, and examples of such ononium cations include monium cations and strontium cations.

[0164] The radiogenic compound is preferably a compound that produces a base by exposure (radiosensitive linear base generator), and more preferably a nitrogen-containing organic compound that produces an amine group.

[0165] Examples of the radiosensitive linear base generating agents include compounds described in Japanese Patent Application Publication Nos. 4-151156, 4-162040, 5-197148, 5-5995, 6-194834, 8-146608, 10-83079 and European Patent No. 622682.

[0166] In addition, as the radiosensitive linear base generator, examples include compounds containing carbamate groups (carbamate bonds), compounds containing acetoxyimine groups, ionic compounds (anion-cation complexes), and compounds containing acetoxyimine groups, etc., preferably compounds containing carbamate groups (carbamate bonds), compounds containing acetoxyimine groups, and ionic compounds (anion-cation complexes).

[0167] Furthermore, as a radiosensitive linear base generator, it is preferable to be a compound having an intramolecular ring structure. Examples of such ring structures include: benzene, naphthalene, anthracene, xanthone, thioxanthone, anthraquinone, fluorene, etc.

[0168] Examples of radiosensitive linear base generators include: 2-nitrobenzylcarbamate, 2,5-dinitrobenzylcyclohexylcarbamate, N-cyclohexyl-4-methylphenylsulfonamide, 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate, etc.

[0169] When the composition for forming the resist underlayer film contains an [E] acid diffusion control agent, the lower limit of the content of the [E] acid diffusion control agent is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass relative to 100 parts by mass of the [A] polymer. The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 20 parts by mass.

[0170] [Preparation method of composition for forming resist underlayer film] The composition for forming resist underlayer film can be prepared by mixing [A] polymer, [B] onium salt, [C] solvent and any other components as needed in a predetermined proportion, preferably by filtering the obtained mixture using a membrane filter with a pore size of 0.5 μm or less.

[0171] [Silicone film formation step] In this step, which is performed before the coating step (I), a silicon film is formed directly or indirectly on the substrate.

[0172] Examples of substrates include silicon substrates, aluminum substrates, nickel substrates, chromium substrates, molybdenum substrates, tungsten substrates, copper substrates, tantalum substrates, titanium substrates, and other metal or semi-metal substrates, among which silicon substrates are preferred. The substrate may also be a substrate on which a silicon nitride film, an aluminum oxide film, a silicon dioxide film, a tantalum nitride film, a titanium nitride film, etc., are formed.

[0173] Silicon-containing films can be formed by coating with a silicon-containing film forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. For example, methods for forming silicon-containing films by coating with a silicon-containing film forming composition include directly or indirectly coating the silicon-containing film forming composition onto a substrate, and then exposing and / or heating the formed coating film to harden it. Commercially available silicon-containing film forming compositions include, for example, "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 using chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0174] The radiation used in the exposure can be, for example, 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.

[0175] The lower limit of the temperature for heating the coating film is preferably 90°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the temperature is preferably 550°C, more preferably 450°C, and even more preferably 300°C.

[0176] 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 of the average thickness 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.

[0177] As an example of indirectly forming a silicon-containing film on a substrate, a silicon-containing film can be formed on a low-dielectric insulating film or an organic underlayer film formed on a substrate.

[0178] [Coating Step (I)] In this step, a composition for forming a resist underlayer film is coated onto the silicon-containing film formed on the substrate. The coating method for the composition for forming the resist underlayer film is not particularly limited; for example, suitable methods such as spin coating, cast coating, or roll coating can be used. This forms a coating film, and the resist underlayer film is formed by the evaporation of the [C] solvent.

[0179] Furthermore, when the composition for forming a resist underlayer film is directly applied to the substrate, the silicon-containing film formation step can be omitted.

[0180] Next, the coating film formed by the coating is heated. Heating the coating film can promote the formation of the resist underlayer film. More specifically, heating the coating film can promote the volatilization of [C] solvent, etc.

[0181] The heating of the coating film can be carried out in an atmospheric environment or in a nitrogen environment. The lower limit of the heating temperature is preferably 100°C, more preferably 150°C, and even more preferably 200°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 heating time is preferably 1,200 seconds, more preferably 600 seconds.

[0182] The lower limit of the average thickness of the formed resist underlayer film is preferably 0.5 nm, more preferably 1 nm, and even more preferably 2 nm. The upper limit of the average thickness is 100 nm, preferably 50 nm, more preferably 20 nm, and even more preferably 10 nm. Furthermore, the method for measuring the average thickness is based on the description in the embodiments.

[0183] [Coating Step (II)] In this step, a resist film forming composition is coated onto the resist underlayer film formed by the resist underlayer film forming composition coating step. There are no particular limitations on the coating method of the resist film forming composition, for example, spin coating method, etc.

[0184] To explain this step in more detail, for example, by pre-baking (hereinafter also referred to as "PB") after applying the resist composition in such a way that the formed resist film becomes a predetermined thickness, the solvent in the coated film evaporates, thereby forming a resist film.

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

[0186] Examples of resist film forming compositions used in this step include: positive or negative chemically amplified resist compositions containing a radiosensitive linear acid generator; positive resist compositions containing an alkali-soluble resin and a quinone diazide-based photosensitive agent; negative resist compositions containing an alkali-soluble resin and a crosslinking agent; and metal-containing resist compositions containing metals such as tin and zirconium.

[0187] [Exposure Step] In this step, the resist film formed by the resist film forming composition coating step is exposed to radiation.

[0188] The radiation used in the exposure can be appropriately selected according to the type of resist film forming composition used. 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, far ultraviolet light is preferred, and more preferably KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F2 excimer laser light (wavelength 157 nm), Kr2 excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., also known as "EUV"), and even more preferably ArF excimer laser light or EUV. In addition, the exposure conditions can be appropriately determined according to the type of resist film forming composition used.

[0189] In addition, in this step, after the exposure, in order to improve the performance of the resist film such as resolution, pattern outline, and developability, a post-exposure baking (hereinafter also referred to as "PEB") can be performed. The PEB temperature and PEB time can be appropriately determined according to the type of resist film forming composition used. 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.

[0190] [Developing Step] In this step, the exposed resist film is developed. At this time, a portion of the resist underlayer film may also be developed. Examples of developing solutions used in this development include alkaline aqueous solutions (alkaline developing solutions) and liquids containing organic solvents (organic solvent developing solutions).

[0191] There are no particular limitations on the alkaline solution used for alkaline development, and known alkaline solutions can be used. Examples of alkaline solutions for alkaline development include aqueous solutions containing at least one of the following alkaline compounds: sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl diethylamine, ethyl dimethylamine, triethanolamine, tetramethyl ammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous solution of TMAH is preferred, and a 2.38% by mass aqueous solution of TMAH is more preferred.

[0192] As the organic solvent developer for developing organic solvents, examples include substances that are the same as those exemplified above as [C] solvents. As the organic solvent developer, ester-based solvents, ether-based solvents, alcohol-based solvents, ketone-based solvents and / or hydrocarbon-based solvents are preferred, ketone-based solvents are more preferred, and 2-heptanone is particularly preferred.

[0193] In this step, cleaning and / or drying may also be performed after development.

[0194] [Etching Step] In this step, etching is performed using the resist pattern (and the resist underlayer film pattern) as a mask. The number of etching operations can be one or multiple times; that is, etching can be performed sequentially using the pattern obtained by etching as a mask. From the viewpoint of obtaining a better pattern shape, multiple etching operations are preferred. In the case of multiple etching operations, for example, etching can be performed sequentially in the order of the silicon film and the substrate. Examples of etching methods include dry etching and wet etching. From the viewpoint of obtaining a better shape for the substrate pattern, dry etching is preferred. In this dry etching, gas plasmas such as oxygen plasma can be used. A semiconductor substrate with a predetermined pattern can be obtained through this etching.

[0195] As dry etching, a known dry etching apparatus can be used, for example. The etching gas used in dry etching can be appropriately selected based on the mask pattern, the elemental composition of the film being etched, etc. Examples include: fluorine-based gases such as CHF3, CF4, C2F6, C3F8, and SF6; chlorine-based gases such as Cl2 and BCl3; oxygen-based gases such as O2, O3, and H2O; reducing gases such as H2, NH3, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HF, HI, HBr, HCl, NO, NH3, and BCl3; and inert gases such as He, N2, and Ar. These gases can also be mixed. When etching the substrate using the pattern of the resist underlayer as a mask, fluorine-based gases are typically used.

[0196] Furthermore, if there is a silicon-containing film remaining on the substrate after the substrate pattern is formed, the silicon-containing film can be removed by performing the removal steps described later.

[0197] 《Resist Underlayer Film Formation Composition》 This resist underlayer film formation composition contains [A] a polymer, [B] an onionium salt, and [C] a solvent. This resist underlayer film formation composition can be suitably used in the semiconductor substrate manufacturing method. [Example]

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

[0199] [Weight Average Molecular Weight (Mw)] The Mw of the polymer was determined by gel permeation chromatography (GPC) using Tosoh (stock) gel permeation chromatography (GPC) columns (two "G2000HXL" and one "G3000HXL") under analytical conditions of flow rate: 1.0 mL / min, dissolution solvent: tetrahydrofuran, and column temperature: 40°C, using monodisperse polystyrene as a standard (detector: differential refractometer).

[0200] [Average film thickness] The average film thickness was determined by measuring the film thickness at any 9 points with a spacing of 5 cm, including the center, on the resist substrate using a spectroelelometric meter (JA WOOLLAM's "M2000D"). The average film thickness was calculated as the average of these film thicknesses.

[0201] <[A] Synthesis of Polymers> The polymers represented by the following formulas (A-1) to (A-2) are synthesized by the following procedure (hereinafter also referred to as "Polymer (A-1) to Polymer (A-2)").

[0202] [Chemical 18]

[0203] In the formulas (A-1) to (A-2), the numbers marked for each repeating unit indicate the proportion (mol%) of that repeating unit.

[0204] [Synthesis Example 1] (Synthesis of Polymer (A-1)) 36 g of 4-ethoxystyrene and 64 g of ethylhexyl methacrylate were dissolved in 130 g of 1-methoxy-3-propanol, and 10 g of dimethyl 2,2'-azobis(2-methylpropionic acid) was added to prepare a monolithic solution. 70 g of 1-methoxy-3-propanol was added to a reaction vessel under nitrogen atmosphere, and the mixture was heated to 80°C. The monolithic solution was added dropwise over 3 hours with stirring. The start of the dropwise addition was set as the start time of the polymerization reaction. After 6 hours of polymerization, the mixture was cooled to below 30°C. 180 g of methanol, 48.1 g of triethylamine, and 8.6 g of water were added to the reaction solution, and the mixture was heated to 70°C. The mixture was stirred and reacted for 6 hours, after which the mixture was cooled to below 30°C. 300 g of methyl isobutyl ketone and 1000 g of 5% oxalic acid solution were added for liquid-liquid extraction, followed by reprecipitation in hexane. After removing the supernatant by decantation, 300 g of propylene glycol monomethyl ether acetate was added, and the mixture was concentrated under reduced pressure to obtain a propylene glycol monomethyl ether acetate solution of polymer (A-1). The Mw of polymer (A-1) was 3,600.

[0205] [Synthesis Example 2] (Synthesis of Polymer (A-2)) A monolithic solution was prepared by adding 43 g of 1-ethylcyclopentyl methacrylate, 33 g of 3-hydroxytricyclo(3.3.1.13,7)decane-1-yl methacrylate, 24 g of 2-oxotetrahydrofuran-3-yl methacrylate, and 16.2 g of dimethyl 2,2'-azobis(2-methylpropionic acid) ester. 300 g of methyl isobutyl ketone was added to a reaction vessel under nitrogen atmosphere, and the mixture was heated to 80°C. The monolithic solution was added dropwise over 3 hours with stirring. The start of the dropwise addition was set as the start time of the polymerization reaction. After 6 hours of polymerization, the mixture was cooled to below 30°C. 300 g of propylene glycol monomethyl ether acetate was added to the reaction solution, and the methyl isobutyl ketone was removed by vacuum concentration to obtain a propylene glycol monomethyl ether acetate solution of polymer (A-2). The Mw of polymer (A-2) is 6,600.

[0206] <Preparation of the composition> The following shows the [A] polymer, [B] onium salt, [C] solvent and [D] crosslinking agent used in the preparation of the composition.

[0207] [[A] Polymer] The synthesized polymers (A-1) to (A-2)

[0208] [[B]onium salts] Examples B-1 to B-13: Compounds represented by the following formulas (B-1) to (B-13) Comparative Examples b-1 to b-2: Compounds represented by the following formulas (b-1) to (b-2)

[0209] [Chemical 19]

[0210] [Chemical 20]

[0211] [Chemical 21]

[0212] [Chemical 22]

[0213] [[C] Solvent] C-1: Propylene glycol monomethyl ether acetate C-2: 4-Methyl-2-pentanol

[0214] [[D] Crosslinking agent] D-1: The compound represented by the following formula (D-1) D-2: The compound represented by the following formula (D-2)

[0215] [Chemical 23]

[0216] [Example 1] 100 parts by mass of (A-1) as polymer [A], 30 parts by mass of (B-1) as ononium salt [B], and 30 parts by mass of (D-1) as crosslinking agent [D] were dissolved in a mixed solvent of 1100 parts by mass of (C-1) and 200 parts by mass of (C-2) as solvent [C]. The obtained solution was filtered using a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0217] [Examples 2 to 15 and Comparative Examples 1 to 2] Except for using the types and amounts of each component shown in Table 1 below, compositions (J-2) to (J-15) and compositions (CJ-1) to (CJ-2) were prepared in the same manner as in Example 1.

[0218] [Table 1] Composition [A] Polymer [B] Onion salt [D] Crosslinking agent [C]solvent type content (by weight) type content (by weight) type content (by weight) type content (by weight) Example 1 J-1 A-1 100 B-1 30 D-1 30 C-1 / C-2 1100 / 200 Example 2 J-2 A-2 100 B-1 30 D-1 30 C-1 / C-2 1100 / 200 Example 3 J-3 A-1 100 B-1 30 D-2 30 C-1 / C-2 1100 / 200 Example 4 J-4 A-1 100 B-2 30 D-1 30 C-1 / C-2 1100 / 200 Example 5 J-5 A-1 100 B-3 30 D-1 30 C-1 / C-2 1100 / 200 Example 6 J-6 A-1 100 B-4 30 D-1 30 C-1 / C-2 1100 / 200 Example 7 J-7 A-1 100 B-5 30 D-1 30 C-1 / C-2 1100 / 200 Example 8 J-8 A-1 100 B-6 30 D-1 30 C-1 / C-2 1100 / 200 Example 9 J-9 A-1 100 B-7 30 D-1 30 C-1 / C-2 1100 / 200 Example 10 J-10 A-1 100 B-8 30 D-1 30 C-1 / C-2 1100 / 200 Example 11 J-11 A-1 100 B-9 30 D-1 30 C-1 / C-2 1100 / 200 Example 12 J-12 A-1 100 B-10 30 D-1 30 C-1 / C-2 1100 / 200 Example 13 J-13 A-1 100 B-11 30 D-1 30 C-1 / C-2 1100 / 200 Example 14 J-14 A-1 100 B-12 30 D-1 30 C-1 / C-2 1100 / 200 Example 15 J-15 A-1 100 B-13 30 D-1 30 C-1 / C-2 1100 / 200 Comparative Example 1 CJ-1 A-1 100 b-1 30 D-1 30 C-1 / C-2 1100 / 200 Comparative Example 2 CJ-2 A-1 100 b-2 30 D-1 30 C-1 / C-2 1100 / 200

[0219] <Evaluation> The prepared composition was used, and the preservation stability and rectangularity of the resist pattern were evaluated by the following methods. The evaluation results are shown in Table 2 below.

[0220] [Storage Stability] The prepared composition was coated on a 12-inch silicon wafer using a spin coater (Tokyo Electron Inc.'s "CLEAN TRACK ACT12") at 1,500 rpm for 30 seconds. The resulting coated film was then heated at 90°C for 60 seconds to form a resist underlayer film. The composition for forming the resist underlayer film on the same day (T=0) is defined as "resist underlayer film (a0)", and the composition for forming the resist underlayer film stored at 60°C for two days (T=2) is defined as "resist underlayer film (a1)". The average thickness of the resist underlayer film (a0) is defined as T0, and the average thickness of the resist underlayer film (a1) is defined as T1. The film thickness change rate (%) is calculated using the following formula and is used as an indicator of storage stability. Film thickness change rate (%) = (|T1-T0| / T0)×100 Regarding storage stability, a film thickness change rate of less than 10% is rated as "A" (good), and a film thickness change rate of more than 10% is rated as "B" (poor).

[0221] <Preparation of EUV Exposure Resist Composition> The EUV exposure resist composition (R-1) is obtained by mixing 100 parts by mass of a polymer having repeating units (1) derived from 4-hydroxystyrene, repeating units (2) derived from styrene and repeating units (3) derived from 4-tert-butoxystyrene (the content ratio of each repeating unit is (1) / (2) / (3)=65 / 5 / 30 (moles)), 1.0 parts by mass of triphenylsyl trifluoromethanesulfonate as a radiosensitive linear acid generator, 4,400 parts by mass of ethyl lactate as a solvent and 1,900 parts by mass of propylene glycol monomethyl ether acetate, and filtering the obtained solution using a filter with a pore size of 0.2 μm.

[0222] [Patterned Rectangularity (EUV Exposure)] An organic underlayer film forming material (JSR HM8006) was applied to a 12-inch silicon wafer using a spin coater (Tokyo Electron's Clean Track Act 12) 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 NFC SOG080) was then applied to the 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 prepared composition was coated onto the formed silicon-containing film, 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. An EUV exposure resist composition (R-1) was coated onto the formed resist underlayer film, 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. Subsequently, the resist film was irradiated with extreme ultraviolet light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, Sigma 0.9, quadrupole illumination, 1-to-1 line and space mask with a linewidth of 16 nm on the wafer)). After irradiation with extreme ultraviolet light, the substrate was heated at 110°C for 60 seconds, and then cooled at 23°C for 60 seconds. Subsequently, a 2.38% by mass tetramethylammonium hydroxide aqueous solution (20°C–25°C) was used for development by the immersion method, followed by rinsing with water and drying to obtain an evaluation substrate with a resist pattern. The length of the resist pattern on the evaluation substrate was measured and observed using a scanning electron microscope (Hitachi High-technologies, Ltd.'s "SU8220"). Regarding pattern rectangularity, a rectangular cross-sectional shape was rated "A" (good), a pattern with a sloping hem was rated "B" (slightly good), and a pattern with residue (defects) was rated "C" (poor).

[0223] [Table 2] Composition Preservation stability Rectangularity of the pattern Example 1 J-1 A A Example 2 J-2 A A Example 3 J-3 A A Example 4 J-4 A A Example 5 J-5 A A Example 6 J-6 A A Example 7 J-7 A A Example 8 J-8 A A Example 9 J-9 A B Example 10 J-10 A B Example 11 J-11 A B Example 12 J-12 A B Example 13 J-13 A B Example 14 J-14 A B Example 15 J-15 A A Comparative Example 1 CJ-1 A C Comparative Example 2 CJ-2 B C

[0224] As shown in Table 2, the composition for forming the resist underlayer film of the embodiment exhibits good storage stability. Furthermore, compared to the resist underlayer film formed by the composition for forming the resist underlayer film of the comparative example, the resist underlayer film formed by the composition for forming the resist underlayer film of the embodiment demonstrates superior pattern rectangularity. [Industrial Applicability]

[0225] According to the semiconductor substrate manufacturing method of the present invention, since a resist underlayer film forming composition capable of forming a resist underlayer film with excellent pattern rectangularity and excellent storage stability is used, a semiconductor substrate can be manufactured efficiently. The resist underlayer film forming composition according to the present invention provides good storage stability and can form a film with excellent pattern rectangularity. Therefore, these are suitable for use in the manufacture of semiconductor devices that are expected to be further miniaturized in the future.

Claims

1. A method for manufacturing a semiconductor substrate, comprising: The step of directly or indirectly coating a resist underlayer film onto a substrate to form a composition; The process includes: applying a resist film forming composition to a resist underlayer film formed by the resist underlayer film forming composition coating step; exposing the resist film formed by the resist film forming composition coating step to radiation; and developing at least the exposed resist film, wherein the resist underlayer film forming composition comprises: a polymer, an onium salt that generates at least one polar group selected from the group consisting of carboxyl and hydroxyl groups by radiation or heat, and a solvent, wherein the onium salt is a strontium salt and the anionic portion of the onium salt has a sulfonate anion.

2. The method for manufacturing a semiconductor substrate as claimed in claim 1, wherein the radiation is extreme ultraviolet light.

3. A method for manufacturing a semiconductor substrate as claimed in claim 1 or claim 2, wherein in the step of developing the exposed resist film, a portion of the resist underlayer film is further developed.

4. A method for manufacturing a semiconductor substrate as claimed in claim 1 or claim 2, wherein the developing solution used in the step of developing the exposed resist film is an alkaline solution.

5. The method for manufacturing a semiconductor substrate as described in claim 1 or claim 2, further comprising, prior to the step of coating the composition for forming the resist underlayer film: The step of forming a silicon-containing film directly or indirectly on a substrate.

6. A composition for forming a resist underlayer film, comprising: a polymer, an onium salt having at least one polar group selected from the group consisting of carboxyl and hydroxyl groups generated by radiation or heat, and a solvent, wherein the onium salt is a strontium salt and the anionic portion of the onium salt has a sulfonate anion.

7. The resist underlayer film forming composition as claimed in claim 6, wherein the polar group is generated in at least the anionic portion of the onium salt by radiation or heat.

8. The resist underlayer film forming composition as claimed in claim 6, wherein at least one of the groups selected from fluorine atoms and fluorinated hydrocarbon groups is bonded to the carbon atom bonded by the sulfonate anion.

9. The resist underlayer film forming composition as claimed in any one of claims 6 to 8, wherein the anionic portion of the onium salt comprises a ring structure.

10. The resist underlayer film forming composition as claimed in any one of claims 6 to 8, wherein the resist underlayer film forming composition further comprises a crosslinking agent.

11. A composition for forming a resist underlayer film as claimed in any one of claims 6 to 8, wherein the polymer has a repeating unit represented by the following formula (3); (in formula (3), R3 is a hydrogen atom, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, substituted or unsubstituted; L3 is a single bond or a divalent linker; R4 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, substituted or unsubstituted).

12. A composition for forming a resist underlayer film as claimed in any one of claims 6 to 8, wherein the polymer has a repeating unit represented by the following formula (4) (except in the case of formula (3); (in formula (4), R5 is a hydrogen atom, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, substituted or unsubstituted; L4 is a single bond or a divalent linker; Ar1 ​​is a monovalent group having 6 to 20 ring members, substituted or unsubstituted).