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

Abstract

Provided are: a composition for forming a resist underlayer film, said composition making it possible to form a resist underlayer film having excellent resist pattern rectangularity; and a method for manufacturing a semiconductor substrate. This composition for forming a resist underlayer film contains a polymer and a solvent. The polymer has a group including at least one hydroxy group selected from the group consisting of formulae (A1) to (A4). (In formulae (A1) to (A4), at least one of Re and Rf is a hydrogen atom. In formula (A4), at least one hydrogen atom is bonded to at least one carbon atom at the β-position of the oxygen atom of OH.)

Description

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

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

[0002] In semiconductor substrate manufacturing, a multilayer resist process is used to form patterns by exposing and developing a resist film that has been laminated on a substrate via a resist underlayer film such as an organic underlayer film or a silicon-containing film. In this process, the resist pattern is used as a mask to etch the resist underlayer film, and the substrate is further etched using the resulting resist underlayer film pattern as a mask, thereby forming a desired pattern on the semiconductor substrate. Various studies have been conducted on compositions for forming resist underlayer films (see International Publication No. 2013 / 141015).

[0003] International Publication No. 2013 / 141015

[0004] In recent years, semiconductor devices have become even more highly integrated, and the exposure light used is tending to be shortened from KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) to extreme ultraviolet light (13.5 nm, hereinafter also referred to as "EUV"). Furthermore, in EUV lithography, metal-containing resist films are increasingly being used instead of organic resist films.

[0005] As the line width of resist patterns becomes finer, pattern rectangularity is required for the underlayer film used for resists to ensure the rectangular shape of the resist pattern.

[0006] The present invention has been made based on the circumstances described above, and its objective is to provide a resist underlayer film formation composition capable of forming a resist underlayer film with excellent resist pattern rectangularity, and a method for manufacturing a semiconductor substrate.

[0007] In one embodiment, the present invention relates to a composition for forming a resist underlayer film, which contains a polymer (hereinafter also referred to as "[A] polymer") and a solvent (hereinafter also referred to as "[B] solvent"), and the polymer has a group containing at least one hydroxy group selected from the group consisting of the following formulas (A1) to (A4) (hereinafter also referred to as "group (X)"). (In the above formulas (A1) to (A4), ２ , ２ , ２ , ｆ , １ , ｅ , ,

[0008] , R ａ２ and R ｂ are each independently a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ａ１ and R ｂ are combined with each other to form a ring structure having 3 to 20 carbon atoms together with the two carbon atoms to which they are attached. R ｃ and R ｄ are each independently a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ｃ and R ｄ are combined with each other to form a ring structure having 3 to 20 carbon atoms together with the carbon atom to which they are attached. Ar １ is a divalent aromatic ring having 3 to 20 carbon atoms, which may be substituted or unsubstituted. R ｅ and R ｆ are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group or a hydrogen atom. However, at least one of R ｅ and R ｆ is a hydrogen atom. Cy １ is a ring structure having 3 to 20 ring members, which is formed together with the two carbon atoms in the formula (A3). Ar ２ is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. Cy ２ is a substituted or unsubstituted alicyclic ring having 4 to 20 carbon atoms, which is formed together with the two carbon atoms in the formula (A4) constituting the aromatic ring of Ar ２ . However, at least one hydrogen atom is bonded to at least one carbon atom at the β-position of the oxygen atom of OH in the formula (A4). * is a bond to another part of the above polymer, respectively.)

[0008] In other embodiments, the present invention relates to a method for manufacturing a semiconductor substrate, comprising the steps of: coating a resist underlayer film forming composition directly or indirectly onto a substrate; forming a resist film on the resist underlayer film formed by the resist underlayer film forming composition coating step; exposing the resist film to radiation; and developing at least the exposed resist film, wherein the resist underlayer film forming composition contains a polymer and a solvent, and the polymer has a group containing at least one hydroxyl group selected from the group consisting of the following formulas (A1) to (A4). (In the above formulas (A1) to (A4), R ａ１ , R ａ２ and R ｂ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ａ１ and R ｂ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the two carbon atoms to which they are bonded. ｃ and R ｄ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ｃ and R ｄ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the carbon atoms to which they are bonded. １ R is a substituted or unsubstituted divalent aromatic ring having 3 to 20 carbon atoms. ｅ and R ｆ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a hydrogen atom. However, R ｅ and R ｆ At least one of them is a hydrogen atom. １ This is a ring structure with 3 to 20 members, formed together with the two carbon atoms in formula (A3). ２ This is a substituted or unsubstituted aromatic ring with 3 to 20 carbon atoms. ２ Ar ２It is a substituted or unsubstituted alicyclic ring with 4 to 20 carbon atoms, formed together with the two carbon atoms in formula (A4) that constitute the aromatic ring. However, at least one hydrogen atom is bonded to at least one carbon atom at the β position of the oxygen atom of the OH group in formula (A4). * indicates a bond with another part of the polymer.

[0009] The resist underlayer film formation composition allows for the formation of a film with excellent resist pattern rectangularity. The semiconductor substrate manufacturing method utilizes a resist underlayer film formation composition capable of forming a resist underlayer film with excellent resist pattern rectangularity, enabling efficient semiconductor substrate manufacturing. Therefore, these can be suitably used in the manufacture of semiconductor devices and the like.

[0010] The following describes in detail the resist underlayer film formation compositions and semiconductor substrate manufacturing methods according to each embodiment of the present invention. Preferred combinations of embodiments are also preferred.

[0011] Composition for forming a resist underlayer film The composition for forming a resist underlayer film (hereinafter also referred to as "the composition") contains [A] a polymer and [B] a solvent. The composition may contain optional components as long as they do not impair the effects of the present invention.

[0012] According to this composition, it is possible to form a resist underlayer film with excellent resist pattern rectangularity. Although the reason for this is not clear, it is presumed to be as follows: The group (X) of the polymer [A] contained in this composition generates water when exposed to heat, light, acid, etc. As a result, the underlayer film obtained with this composition generates water when exposed to extreme ultraviolet light or when the film is heated, creating a sufficient difference in solubility in the interface region on the underlayer side of the organic resist film, and in particular promoting the insolubilization of metal-containing resist films, thereby suppressing pattern trailing at the bottom of the resist film and ensuring the rectangularity of the resist pattern.

[0013] The following describes each component contained in the composition.

[0014] <[A] Polymer> The [A] polymer has a group (X). The [A] polymer may have one or more groups (X). The composition may contain one or more [A] polymers. The form of the [A] polymer is not particularly limited and may be any polymerization reaction such as an addition polymerization reaction, polycondensation reaction, polyaddition reaction, or addition-condensation reaction.

[0015] Group (X) is a group containing at least one hydroxyl group selected from the group consisting of the following formulas (A1) to (A4). (In the above formulas (A1) to (A4), R ａ１ , R ａ２ and R ｂ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ａ１ and R ｂ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the two carbon atoms to which they are bonded. ｃ and R ｄ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ｃ and R ｄ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the carbon atoms to which they are bonded. １ R is a substituted or unsubstituted divalent aromatic ring having 3 to 20 carbon atoms. ｅ and R ｆ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a hydrogen atom. However, R ｅ and R ｆ At least one of them is a hydrogen atom. １ This is a ring structure with 3 to 20 members, formed together with the two carbon atoms in formula (A3). ２ This is a substituted or unsubstituted aromatic ring with 3 to 20 carbon atoms. ２ Ar ２It is a substituted or unsubstituted alicyclic ring with 4 to 20 carbon atoms, formed together with the two carbon atoms in formula (A4) that constitute the aromatic ring. However, at least one hydrogen atom is bonded to at least one carbon atom at the β position of the oxygen atom of the OH group in formula (A4). * indicates a bond with another part of the polymer.

[0016] R ａ１ , R ａ２ and R ｂ Examples of monovalent organic groups having 1 to 20 carbon atoms represented by include monovalent hydrocarbon groups having 1 to 20 carbon atoms, a group (a) having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the terminal end of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group or group (a) are replaced with a monovalent heteroatom-containing substituent, or combinations thereof.

[0017] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.

[0018] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0019] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic cycloalkyl groups such as cyclopentyl and cyclohexyl groups; monocyclic cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl groups; polycyclic saturated hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, pinanyl, caranyl, and bornanyl groups; and polycyclic unsaturated hydrocarbon groups such as norborneyl and tricyclodecenyl groups.

[0020] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, anthracenyl, and pyrenyl groups; and aralkyl groups such as benzyl and phenethyl groups.

[0021] Examples of heteroatoms that constitute a divalent heteroatom-containing linking group or a monovalent heteroatom-containing substituent include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0022] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ -Or groups that combine these. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0023] Examples of monovalent heteroatom-containing substituents include hydroxyl groups, sulfanyl groups, cyano groups, amino groups, nitro groups, and halogen atoms.

[0024] R ａ１ , R ａ２ and R ｂ The above organic groups in are preferably C1-C10 alkyl groups, C1-C10 alkoxy groups, C6-C14 aryl groups, or cyano groups, more preferably C1-C5 alkyl groups, C1-C5 alkoxy groups, C6-C10 aryl groups, or cyano groups, and even more preferably methyl groups, ethyl groups, methoxy groups, ethoxy groups, phenyl groups, or cyano groups. Among these, R ａ１ , R ａ２ and R ｂ A hydrogen atom or a methyl group is preferred as the element.

[0025] R ａ１ and R ｂ When these are combined with each other, the resulting ring structure with 3 to 20 carbon atoms, formed together with the two carbon atoms to which they are bonded, is R ａ１ Examples include structures corresponding to monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, as shown in the above. Among them, R ａ１ and R ｂThe resulting ring structure having 3 to 20 carbon atoms is preferably a cycloalkane having 3 to 10 carbon atoms, more preferably a monocyclic cycloalkane having 3 to 8 carbon atoms, and even more preferably cyclopentane or cyclohexane.

[0026] R ｃ and R ｄ As a monovalent organic group having 1 to 20 carbon atoms, R ａ１ Monovalent organic groups having 1 to 20 carbon atoms, such as those represented by the formulas shown, can be suitably used.

[0027] R ｃ and R ｄ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, which is R ａ１ and R ｂ The above-mentioned ring structure having 3 to 20 carbon atoms, formed by this, can be suitably adopted.

[0028] R ｃ and R ｄ For example, it is either a hydrogen atom or R ｃ and R ｄ It is preferable that these are combined to form cyclopentane or cyclohexane.

[0029] Ar １ Examples of divalent aromatic rings having 3 to 20 carbon atoms in Ar include groups obtained by removing two hydrogen atoms from an aromatic ring having 3 to 20 carbon atoms. Examples of the above aromatic rings having 3 to 20 carbon atoms include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, and perylene rings, heteroaromatic rings such as furan rings, pyrrole rings, thiophene rings, phosphole rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, and triazine rings, or combinations thereof. １ The aromatic ring is preferably a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

[0030] Ar １When it has a substituent, examples of the substituent include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, an alkoxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonyl group, an alkoxycarbonyloxy group such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an acyl group such as a formyl group, an acetyl group, a propionyl group, a butyryl group, a benzoyl group, an acyloxy group such as an acetoxy group, a benzoyloxy group, a hydroxy group, a cyano group, a nitro group, an oxo group (=O), and the like.

[0031] R ｅ and R ｆ As the monovalent organic group having 1 to 20 carbon atoms represented by, R ａ１ etc., a monovalent organic group having 1 to 20 carbon atoms represented by can be preferably adopted. R ｅ and R<� ｆ As the above organic group in, an alkyl group having 1 to 10 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms is more preferable, and a methyl group and an ethyl group are even more preferable. Among them, as the group other than the hydrogen atom in R ｅ and R ｆ a hydrogen atom, a methyl group or a hydroxy group is preferable, and a hydrogen atom or a methyl group is more preferable.

[0032] Cy １ As the ring structure having 3 to 20 ring members formed together with two carbon atoms in the formula (A3) represented by, the structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms shown in R ａ１ etc. can be mentioned.

[0033] As the above ring structure, an aliphatic heterocyclic structure can also be adopted. Examples of the aliphatic heterocyclic structure include an oxygen atom-containing aliphatic heterocyclic structure such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, dioxane, etc.; a nitrogen atom-containing aliphatic heterocyclic structure such as aziridine, pyrrolidine, piperidine, piperazine, etc.; a sulfur atom-containing aliphatic heterocyclic structure such as thietane, thiolane, thiane, etc.; an aliphatic heterocyclic structure containing a plurality of types of heteroatoms such as morpholine, 1,2-oxathiolane, 1,3-oxathiolane, etc.; an oxygen atom-containing aromatic heterocyclic structure such as furan, benzofuran, etc.; a nitrogen atom-containing aromatic heterocyclic structure such as pyrrole, pyrazole, triazine, etc.; a sulfur atom-containing aromatic heterocyclic structure such as thiophene, etc.; an aromatic heterocyclic structure containing a plurality of types of heteroatoms such as oxazole, isothiazole, thiazine, etc.; and the like.

[0034] The above aliphatic heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal structure or a combination thereof.

[0035] Cy １ The above ring structure having 3 to 20 ring members represented by Cy may have a substituent. As the substituent of Cy １ preferably, a substituent that Ar １ can have can be adopted.

[0036] Cy １ As the above ring structure having 3 to 20 ring members represented by Cy, a monocyclic or polycyclic cycloalkane having 3 to 20 carbon atoms is preferable, a monocyclic or polycyclic cycloalkane having 3 to 12 carbon atoms is more preferable, and cyclopentane, cyclohexane, pinane, bornane, norbornane are even more preferable.

[0037] Ar ２ As the aromatic ring having 3 to 20 carbon atoms in Ar １ preferably, the above divalent aromatic ring having 3 to 20 carbon atoms in Ar ２ can be adopted. As the aromatic ring of Ar

[0038] Ar ２ If it has substituents, the substituents are Ar １ The substituents that it may have can be suitably adopted.

[0039] Cy ２ As for alicyclic rings with 4 to 20 carbon atoms, R ａ１ Examples include structures corresponding to C4-C20 monovalent alicyclic hydrocarbon groups with C3-C20, as shown in the above. ２ As the alicyclic ring having 4 to 20 carbon atoms, cycloalkanes having 3 to 10 carbon atoms are preferred, monocyclic cycloalkanes having 3 to 8 carbon atoms are more preferred, and cyclopentane and cyclohexane are even more preferred.

[0040] Cy ２ If it has substituents, the substituents are Ar １ The substituents that it may have can be suitably adopted.

[0041] Note that the bond between the two carbon atoms in formula (A4) is Ar ２ This also includes π-conjugated bonds that constitute part of the aromatic ring.

[0042] Specific examples of the group (X) represented by the above formula (A1) include, for example, the structure represented by the following formula.

[0043]

[0044] Specific examples of the group (X) represented by the above formula (A2) include, for example, the structure represented by the following formula.

[0045]

[0046] Specific examples of the group (X) represented by the above formula (A3) include, for example, the structure represented by the following formula.

[0047]

[0048] Specific examples of the group (X) represented by the above formula (A4) include, for example, the structure represented by the following formula.

[0049]

[0050] The specific mode of water generation in group (X) is shown in the following scheme, using group (X) represented by the above formula (A1) as a representative example. The same applies to other groups (X).

[0051]

[0052] It is presumed that the above scheme proceeds through the action of heat, light, acid, or a combination thereof, which causes the hydroxyl group and the hydrogen atom bonded to the α-carbon of the carbon atom to which the hydroxyl group is bonded (hereinafter also called "OH carbon") to be eliminated as water, or the hydroxyl group and protons in the system to associate and are eliminated as water, and in response, the β-hydrogen is abstracted by association with water in the system, and the electron that was bonded to the β-hydrogen shifts to the side bonded to the OH carbon.

[0053] [A] The polymer is preferably an addition polymerization product obtained by a radical polymerization reaction, and more preferably an acrylic polymer.

[0054] [A] The polymer preferably has repeating units represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"). (In the above formula (1), R ０ L is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １ X is a 1+n valence linking group or single bond. X is a group (X) containing the hydroxyl group described above. n is an integer from 1 to 5. If n is 2 or greater, multiple Xs are either identical or different from each other.

[0055] R ０ In this, the monovalent hydrocarbon group having 1 to 20 carbon atoms is R in the above formulas (A1) to (A4). ａ１ The monovalent hydrocarbon groups having 1 to 20 carbon atoms, as shown above, can be suitably adopted.

[0056] R ０ If it has substituents, the substituent is Ar of formula (A2) above. １ The substituents that can be present can be suitably adopted.

[0057] R０ A hydrogen atom or a methyl group is preferred as the element.

[0058] L １ Examples of 1+n valency linking groups represented by include hydrocarbons, -COO-, -OCO-, -O-CO-O-, -CONH-, -NHCO-, -O-, -S-, -CO-, or groups obtained by removing hydrogen atoms from structures that combine these, resulting in an overall 1+n valency.

[0059] L １ The hydrocarbons in this case are R in the above formulas (A1) to (A4). ａ１ Structures corresponding to the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown above can be suitably adopted. In particular, L １ The hydrocarbons in this product are preferably chain hydrocarbons having 1 to 10 carbon atoms, alicyclic hydrocarbons having 3 to 10 carbon atoms, aromatic hydrocarbons having 6 to 10 carbon atoms, or combinations thereof, with methane, ethane, propane, n-butane, isobutane, cyclopentane, cyclohexane, benzene, or combinations thereof being more preferred.

[0060] L １ Preferably, the groups are methane, ethane, propane, n-butane, isobutane, benzene, -COO-, -OCO-, -CONH-, -O-, -CO-, or a combination thereof, from which 1+n hydrogen atoms have been removed, or a single bond.

[0061] n is preferably an integer between 1 and 4, more preferably an integer between 1 and 3, even more preferably 1 or 2, and particularly preferably 1.

[0062] Specific examples of monomers that provide a repeating unit (1) include compounds represented by the following formula.

[0063]

[0064]

[0065]

[0066]

[0067] In the above formula, R０ This is equivalent to equation (1) above.

[0068] [A] The lower limit of the content of repeating unit (1) in the total number of repeating units constituting the polymer (the total content if there are multiple types) is preferably 3 mol%, more preferably 10 mol%, and even more preferably 20 mol%. The upper limit of the above content may be 100 mol%, 80 mol%, 60 mol%, 50 mol%, or 40 mol%.

[0069] [A] The polymer preferably further has repeating units represented by the following formula (2) (which are different from the case of formula (1) above) (hereinafter also referred to as "repeating unit (2)"). [A] The polymer may have one or more types of repeating units (2). (In formula (2), R ３Ａ L is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３Ａ R is a single bond or a divalent linking group. ４Ａ (This group is selected from the group consisting of groups represented by any of the following formulas (2-1) to (2-8).) (In formulas (2-1) to (2-3), (2-7), R ８Ａ , R ９Ａ , R １０Ａ , R １２Ａ and R １３Ａ Each of these is independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (2-2), Cy is a ring structure with 3 to 20 members, formed together with the two carbon atoms in the formula. １１Ａ is a hydrogen atom, a monovalent organic group with 1 to 20 carbon atoms, or a single bond. ** is a bond with an atom constituting Cy. However, R １１Ａ If it is a single bond, R １１Ａ It combines with **. In equations (2-1) to (2-8), R ７Ａ * is a divalent organic group or single bond having 1 to 20 carbon atoms. ３Ａ (This is a bonding bond with the constituent atoms.)

[0070] R ３ＡAs a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formulas (A1) to (A4), R ａ１ Monovalent hydrocarbon groups having 1 to 20 carbon atoms, as shown in the above, can be suitably used. ３Ａ If it has substituents, the substituents are Ar in formula (A2) above. １ The groups listed as substituents are examples of this.

[0071] L ３Ａ The divalent linking group represented by is L in formula (1) above. １ Examples include groups where n is 1 among the groups listed as 1+n valence linking groups represented by L. ３Ａ As a single bond, -COO- ＊ ( ＊ R ４Ａ It is a bonding bond with ) or a benzenediyl group is preferred.

[0072] In the above equations (2-1) to (2-3) and (2-7), R ８Ａ ~R １３Ａ As a monovalent organic group having 1 to 20 carbon atoms represented by the above formula (A1), R １１ A monovalent organic group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0073] R ８Ａ ~R １３Ａ Each of these is preferably a hydrogen atom or a methyl group, and more preferably both are hydrogen atoms.

[0074] In formula (2-2) above, the ring structure with 3 to 20 members, which is formed together with the two carbon atoms in the formula represented by Cy, is as follows: In formula (A1) above, R １１ A ring structure corresponding to a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably adopted. As Cy, a cycloalkane ring having 5 to 10 carbon atoms is preferred, and a cyclopentane ring, cyclohexane ring, or cycloheptane ring is more preferred.

[0075] In the above equations (2-1) to (2-8), R ７Ａ As a divalent organic group having 1 to 20 carbon atoms represented by the above R ８Ａ ~R １３ＡA monovalent organic group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably used, with one hydrogen atom removed.

[0076] R ７Ａ Preferred linkages include single bonds, divalent hydrocarbon groups having 1 to 10 carbon atoms, or combinations of divalent hydrocarbon groups having 1 to 10 carbon atoms and divalent heteroatom-containing linkages. Preferred divalent hydrocarbon groups having 1 to 10 carbon atoms include methylene groups and ethanediyl groups. Preferred divalent heteroatom-containing linkages include -O-, -CO-, or combinations thereof.

[0077] Specific examples of repeating units (2) include, for example, the repeating unit represented by the following formula.

[0078]

[0079] In the above formula, R ３A This is equivalent to equation (2) above.

[0080] When polymer [A] has repeating units (2), the lower limit of the content of repeating units (2) in the total repeating units constituting polymer [A] (total content if multiple types are included) is preferably 20 mol%, more preferably 30 mol%, and even more preferably 40 mol%. The upper limit of the above content is preferably 95 mol%, more preferably 85 mol%, and even more preferably 80 mol%. By setting the content of repeating units (2) within the above range, a high level of resist pattern rectangularity can be achieved.

[0081] [A] The polymer may have other repeating units (different from formula (1) or (2) above), such as an onium salt structure containing a sulfonate anion and a sulfonium cation, an onium salt structure containing a sulfonate anion and an iodonium cation, or other repeating units that generate acid upon exposure, a repeating unit having a phenolic hydroxyl group, a repeating unit having a fluorine atom or an iodine atom, or a repeating unit having an acid-dissociable group. An "acid-dissociable group" is a group that substitutes a hydrogen atom, such as a carboxyl group, a phenolic hydroxyl group, an alcoholic hydroxyl group, or a sulfo group, and dissociates upon the action of an acid. Examples of repeating units having an acid-dissociable group include a repeating unit having a tertiary alkyl ester moiety, a repeating unit having a structure in which an aromatic group and an aliphatic group are bonded to the secondary carbon constituting the secondary alkyl ester moiety, a repeating unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a repeating unit having an acetal bond. [A] If the polymer contains other repeating units, the lower limit of the proportion of other repeating units to the total repeating units constituting the polymer (the total proportion if there are multiple types) may be 2 mol%, 5 mol%, or 8 mol%. The upper limit of the above proportion may be 90 mol%, 85 mol%, or 80 mol%.

[0082] [A] The lower limit of the weight-average molecular weight (Mw) of the polymer is preferably 2000, more preferably 3000, and even more preferably 4000. The upper limit of the molecular weight is preferably 15000, more preferably 12000, and even more preferably 10000. The method for measuring the weight-average molecular weight is as described in the examples.

[0083] [A] The lower limit of the number-average molecular weight (Mn) of the polymer is preferably 1000, more preferably 2000, and even more preferably 3000. The upper limit of the molecular weight is preferably 12000, more preferably 8000, and even more preferably 5000. The method for measuring the number-average molecular weight is as described in the examples.

[0084] The lower limit of the content of polymer [A] in the resist underlayer film forming composition is preferably 0.05% by mass, more preferably 0.1% by mass, and even more preferably 0.2% by mass, based on the total mass of polymer [A] and solvent [B]. The upper limit of the above content is preferably 1.5% by mass, more preferably 1.0% by mass, and even more preferably 0.8% by mass, based on the total mass of polymer [A] and solvent [B].

[0085] The content of the polymer [A] in the components other than the solvent [B] in the resist underlayer film forming composition may be 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass.

[0086] [Method for synthesizing polymers A] Polymers A can be synthesized by radical polymerization, ionic polymerization, polycondensation, polyaddition, addition condensation, etc., depending on the type of monomer. For example, when synthesizing polymer A by radical polymerization, the monomers that give each repeating unit can be polymerized in a suitable solvent using a radical polymerization initiator, etc.

[0087] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2'-azobisisobutyrate, and dimethyl-2,2'-azobis(2-methylpropionate); and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. These radical initiators can be used individually or in combination of two or more.

[0088] The solvent used in the polymerization described above can preferably be the solvent [B] described later. These solvents used in polymerization may be used individually or in combination of two or more.

[0089] The reaction temperature in the polymerization described above is usually 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is usually 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0090] <[B] Solvent> The [B] solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer and any optional components contained therein as needed.

[0091] [B] Examples of solvents include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, and nitrogen-containing solvents. [B] Solvents can be used individually or in combination of two or more.

[0092] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0093] Examples of ester solvents include carbonate solvents such as diethyl carbonate, acetic acid monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate solvents such as diethylene glycol acetate monomethyl ether and propylene glycol acetate monomethyl ether, and lactate ester solvents such as methyl lactate and ethyl lactate.

[0094] Examples of alcohol-based solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, 4-methyl-2-pentanol, and 2,2-dimethyl-1-propanol, and polyhydric alcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0095] Examples of ketone solvents include linear ketone solvents such as methyl ethyl ketone, 4-methyl-2-pentanone (methyl isobutyl ketone), and 2-heptanone, as well as cyclic ketone solvents such as cyclohexanone.

[0096] Examples of ether-based solvents include linear ether solvents such as n-butyl ether, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0097] Examples of nitrogen-containing solvents include linear nitrogen-containing solvents such as N,N-dimethylacetamide and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0098] [B] As the solvent, ether-based solvents or ester-based solvents are preferred, polyhydric alcohol partial ether-based solvents or polyhydric alcohol partial ether carboxylate-based solvents are more preferred, and propylene glycol monomethyl ether and propylene glycol acetate monomethyl ether are even more preferred.

[0099] [Optional Components] The resist underlayer film forming composition may contain optional components as long as they do not impair the effects of the present invention. Examples of optional components include crosslinking agents, acid generators, base generators, dehydrating agents, acid diffusion control agents, surfactants, and defoaming agents. Specific examples of base generators include, for example, "U-CAT® SA1", "U-CAT® SA102", "U-CAT® SA102-50", "U-CAT® SA106", "U-CAT® SA112", "U-CAT® SA506", "U-CAT® SA603", "U-CAT® 1000", "U-CAT® 1102", "U-CAT® 2000", "U-CAT® 2024", "U-CAT® 2026", "U-CAT® 2030", "U-CAT (Registered Trademark) Examples include "Trademark 2110", "U-CAT (Registered Trademark) 2313", "U-CAT (Registered Trademark) 651M", "U-CAT (Registered Trademark) 660M", "U-CAT (Registered Trademark) 18X", "TMED", "U-CAT (Registered Trademark) 201G", "U-CAT (Registered Trademark) 202", "U-CAT (Registered Trademark) 420A", "U-CAT (Registered Trademark) 130", "U-CAT (Registered Trademark) 891", "POLYCAT (Registered Trademark) 8", "POLYCAT (Registered Trademark) 9", "POLYCAT (Registered Trademark) 12", and "POLYCAT (Registered Trademark) 41" (all are product names, manufactured by Sunapro Co., Ltd.). As for defoaming agents, known defoaming agents can be used, including alcohol defoaming agents, phosphate ester defoaming agents, fatty acid ester defoaming agents, polyether defoaming agents, and silicone defoaming agents. Examples of fatty acid ester defoaming agents include methyl laurate, methyl palmitate, methyl stearate, propyl butyrate, butyl butyrate, ethyl isovalerate, and isobutyl propionate, with propyl butyrate and butyl butyrate being preferred. Ketone solvents such as 2-heptanone may also be used as defoaming agents. Optional components can be used individually or in combination of two or more. The content ratio of the optional components in the resist underlayer film forming composition can be appropriately determined depending on the type of optional component.

[0100] [Method for preparing a composition for forming a resist underlayer film] The resist underlayer film forming composition can be prepared by mixing [A] polymer, [B] solvent, and optionally any other components in a predetermined ratio, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.5 μm or less.

[0101] 《Method for Manufacturing a Semiconductor Substrate》 The method for manufacturing the semiconductor substrate includes a step of directly or indirectly coating a resist underlayer film forming composition onto a substrate (hereinafter also referred to as the "resist underlayer film forming composition coating step"), a step of forming a resist film on the resist underlayer film formed by the resist underlayer film forming composition coating step (hereinafter also referred to as the "resist film forming step"), a step of exposing the resist film with radiation (hereinafter also referred to as the "exposure step"), and a step of developing at least the exposed resist film (hereinafter also referred to as the "development step").

[0102] According to the semiconductor substrate manufacturing method, by using a predetermined resist underlayer film formation composition in the coating step, a resist underlayer film with excellent resist pattern rectangularity can be formed, thereby enabling the manufacture of a semiconductor substrate with a good pattern shape.

[0103] The method for manufacturing the semiconductor substrate may further include, if necessary, a step of forming an organic underlayer film directly or indirectly on the substrate before the resist underlayer film formation composition coating step (hereinafter also referred to as the "organic underlayer film formation step").

[0104] The method for manufacturing the semiconductor substrate may further include, if necessary, a step of forming a silicon-containing film on the substrate directly or indirectly (hereinafter also referred to as the "silicon-containing film formation step") prior to the resist underlayer film formation composition coating step.

[0105] The following describes each step when the optional steps of forming an organic underlayer film and forming a silicon-containing film are included.

[0106] [Organic Underlayer Formation Process] In this process, an organic underlayer is formed directly or indirectly on the substrate before the resist underlayer formation composition coating process described above. This process is optional. Through this process, an organic underlayer is formed directly or indirectly on the substrate.

[0107] Examples of substrates include insulating films such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane, as well as resin substrates. Furthermore, the substrate may be one that has been patterned with features such as wiring trenches and plug grooves (vias).

[0108] An organic underlayer can be formed by coating with an organic underlayer-forming composition. Methods for forming an organic underlayer by coating with an organic underlayer-forming composition include, for example, directly or indirectly coating a substrate with the composition and then curing the resulting coating by heating or exposure. Examples of organic underlayer-forming compositions include JSR Corporation's "HM8006". The heating and exposure conditions can be appropriately determined depending on the type of organic underlayer-forming composition used.

[0109] Examples of cases where an organic underlayer film is indirectly formed on a substrate include forming the organic underlayer film on a low-dielectric insulating film formed on the substrate.

[0110] [Silicon-containing film formation process] In this process, a silicon-containing film is formed on the substrate either directly or indirectly.

[0111] As the substrate, the substrate exemplified in the organic underlayer film formation process described above can be suitably used.

[0112] Silicon-containing films can be formed by coating with a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. Methods for forming silicon-containing films by coating with a silicon-containing film-forming composition include, for example, directly or indirectly coating a substrate with the silicon-containing film-forming composition and then curing the resulting coating by exposure and / or heating. 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 oxidizite films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD). Heating and exposure conditions can be appropriately determined depending on the type of silicon-containing film-forming composition used.

[0113] Examples of cases where a silicon-containing film is indirectly formed on a substrate include forming a silicon-containing film on a low-dielectric insulating film or an organic underlayer film formed on the substrate.

[0114] [Coating Process for Resist Underlayer Formation Composition] In this process, the resist underlayer formation composition is coated onto the silicon-containing film formed on the substrate. The coating method for the resist underlayer formation composition is not particularly limited and can be carried out by any suitable method, such as rotary coating, casting coating, or roll coating. A coating film is formed as a result, and the resist underlayer is formed by the volatilization of the solvent [B].

[0115] Furthermore, if the resist underlayer film formation composition is applied directly to the substrate, the above-mentioned organic underlayer film formation step and silicon-containing film formation step may be omitted.

[0116] Next, the coating film formed by the above coating process is heated. Heating the coating film promotes the formation of the resist underlayer film. More specifically, heating the coating film promotes the volatilization of solvent [B], etc.

[0117] The above-mentioned coating film may be heated in an atmospheric environment or in a nitrogen atmosphere. The lower limit of the heating temperature is preferably 100°C, more preferably 150°C, and even more preferably 180°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, and even more preferably 600 seconds.

[0118] The lower limit of the film thickness (average thickness) of the resist underlayer film formed is preferably 0.5 nm, more preferably 1 nm, and even more preferably 2 nm. The upper limit of the average thickness is preferably 15 nm, more preferably 12 nm, even more preferably 8 nm, and particularly preferably 5 nm. The method for measuring the average thickness is as described in the examples.

[0119] [Resist Film Formation Process] In this process, a resist film is formed on the resist underlayer film formed by the resist underlayer film forming composition coating process described above. The resist film is preferably formed using the resist film forming composition. The resist film may be either a coated film or a deposited film, but it is preferably a coated film. There are no particular limitations on the coating method of the resist film forming composition, and examples include rotary coating.

[0120] Examples of resist film-forming compositions used in this process include positive or negative type chemically amplified resist compositions containing a radiation-sensitive acid generator, positive type resist compositions containing an alkali-soluble resin and a quinone diazide-based photosensitive agent, negative type resist compositions containing an alkali-soluble resin and a crosslinking agent, and metal-containing resist film-forming compositions containing metals such as tin, zirconium, and hafnium. Among these, compositions subjected to exposure to extreme ultraviolet light are preferred as resist film-forming compositions, and positive or negative type chemically amplified resist compositions containing a radiation-sensitive acid generator, and metal-containing resist compositions containing metals such as tin, zirconium, and hafnium can be suitably used.

[0121] The above-mentioned resist film preferably contains a metal. Such a metal-containing resist film is preferably formed using a metal-containing resist film forming composition.

[0122] (Composition for forming metal-containing resist films) The composition for forming metal-containing resist films contains a metal-containing compound (hereinafter also referred to as "metal-containing compound (A)") and a solvent (hereinafter also referred to as "solvent (F)"), and it is preferable that the content ratio of the metal-containing compound (A) to the components other than solvent (F) in the above metal-containing resist film forming composition is 50% by mass or more. The above metal-containing resist film forming composition may further contain other components.

[0123] (Metal-containing compound (A)) Metal-containing compound (A) is a compound containing metal atoms. Metal-containing compound (A) can be used alone or in combination of two or more types. Furthermore, the metal atoms constituting metal-containing compound (A) can be used alone or in combination of two or more types. Here, "metal atom" is a concept that includes metalloids, namely boron, silicon, germanium, arsenic, antimony, and tellurium.

[0124] The metal atoms constituting the metal-containing compound (A) are not particularly limited, and examples include metal atoms from groups 3 to 16. Specific examples of the above metal atoms include, for example, group 4 metal atoms such as titanium, zirconium, and hafnium; group 5 metal atoms such as tantalum; group 6 metal atoms such as chromium and tungsten; group 8 metal atoms such as iron and ruthenium; group 9 metal atoms such as cobalt; group 10 metal atoms such as nickel; group 11 metal atoms such as copper; group 12 metal atoms such as zinc, cadmium, and mercury; group 13 metal atoms such as boron, aluminum, gallium, indium, and thallium; group 14 metal atoms such as germanium, tin, and lead; group 15 metal atoms such as antimony and bismuth; and group 16 metal atoms such as tellurium.

[0125] The metal atoms constituting the metal-containing compound (A) may include a first metal atom belonging to Group 4, Group 12, or Group 14 of the periodic table, and belonging to Period 4, Period 5, or Period 6. That is, the metal atoms may include at least one of titanium, zirconium, hafnium, zinc, cadmium, mercury, germanium, tin, and lead. In this way, the inclusion of a first metal atom in the metal-containing compound (A) promotes the emission of secondary electrons in the exposed area of ​​the resist film and the change in the solubility of the metal-containing compound (A) in the developer due to these secondary electrons. As a result, the rectangularity of the pattern can be improved. Tin or zirconium is preferred as the first metal atom.

[0126] The metal-containing compound (A) preferably further contains atoms other than metal atoms. Examples of these other atoms include carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms, phosphorus atoms, sulfur atoms, halogen atoms, etc., with carbon atoms, hydrogen atoms, and oxygen atoms being preferred among these. The other atoms in the metal-containing compound (A) can be used individually or in combination of two or more types.

[0127] The lower limit of the content of the metal-containing compound (A) in the metal-containing resist film-forming composition, calculated on a solid content basis, is preferably 70% by mass, more preferably 90% by mass, and even more preferably 95% by mass. The above content may also be 100% by mass. Here, the solid content in the metal-containing resist film-forming composition refers to components other than the solvent (F) described later.

[0128] (Method for synthesizing metal-containing compound (A)) Metal-containing compound (A) can be obtained, for example, by performing a hydrolysis condensation reaction, ligand exchange reaction, etc., on a metal compound having a metal atom and a hydrolyzable group, a hydrolysate of this metal compound, a hydrolysis condensate of the above metal compound, or a combination thereof. The above metal compounds can be used individually or in combination of two or more.

[0129] The metal-containing compound (A) is preferably derived from a metal compound having a metal atom and a hydrolyzable group represented by the following formula (4) (hereinafter also referred to as "metal compound precursor (1)"). By using such a metal compound precursor (1), a stable metal-containing compound (A) can be obtained.

[0130] In the above formula (4), M is a metal atom. Ａ is a ligand or a monovalent organic group having 1 to 20 carbon atoms. a1 is an integer from 0 to 6. If a1 is 2 or more, multiple L １ Q may be the same or different. Q is a monovalent hydrolyzable group. b1 is an integer from 2 to 6. Multiple Qs may be the same or different. Note that L Ａ This is a ligand or organic group that does not correspond to Q.

[0131] The metal atom represented by M is preferably a metal atom of Group 14, and more preferably tin.

[0132] The hydrolyzable group represented by Q can be appropriately changed in accordance with the metal atom represented by M, but examples include substituted or unsubstituted ethynyl groups, halogen atoms, alkoxy groups, alkylcarbonyloxy groups, substituted or unsubstituted amino groups, etc.

[0133] The substituents in the substituted or unsubstituted ethynyl group and the substituted or unsubstituted amino group represented by Q are preferably monovalent hydrocarbon groups having 1 to 20 carbon atoms, more preferably linear hydrocarbon groups, and even more preferably alkyl groups.

[0134] Examples of halogen atoms represented by Q include fluorine, chlorine, bromine, and iodine atoms. Among these, chlorine atoms are preferred.

[0135] Examples of alkoxy groups represented by Q include methoxy, ethoxy, n-propoxy, i-propoxy, and n-butoxy groups. Among these, ethoxy, i-propoxy, and n-butoxy groups are preferred.

[0136] Examples of alkylcarbonyloxy groups represented by Q include acetoxy group, ethylcarbonyloxy group, propylcarbonyloxy group, n-butylcarbonyloxy group, t-butylcarbonyloxy group, t-amylcarbonyloxy group, n-hexylcarbonyloxy group, and n-octylcarbonyloxy group. Among these, the acetoxy group is preferred.

[0137] Examples of substituted or unsubstituted amino groups represented by Q include amino groups, methylamino groups, dimethylamino groups, diethylamino groups, and dipropylamino groups. Among these, dimethylamino groups and diethylamino groups are preferred.

[0138] The following describes preferred combinations of a metal atom represented by M and a hydrolyzable group represented by Q. When the metal atom represented by M is tin, the hydrolyzable group represented by Q is preferably a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an alkylcarbonyloxy group, and a substituted or unsubstituted amino group, with a halogen atom being more preferred. When the metal atom represented by M is germanium, the hydrolyzable group represented by Q is preferably a halogen atom, an alkoxy group, an alkylcarbonyloxy group, and a substituted or unsubstituted amino group. When the metal atom represented by M is hafnium, zirconium, or titanium, the hydrolyzable group represented by Q is preferably a halogen atom, an alkoxy group, or an alkylcarbonyloxy group.

[0139] L Ａ Ligands represented by this include monodentate ligands and polydentate ligands.

[0140] Examples of the monodentate ligands mentioned above include hydroxo ligands, nitro ligands, and ammonia.

[0141] Examples of the polydentate ligands mentioned above include hydroxy acid esters, β-diketones, β-ketoesters, malonic acid diesters in which the α-carbon atom may be substituted, hydrocarbons having a π bond, ligands derived from these compounds, and diphosphines.

[0142] Examples of the above-mentioned diphosphines include 1,1-bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, and 1,1'-bis(diphenylphosphino)ferrocene.

[0143] L Ａ The monovalent organic group represented by is R in the above formulas (2-1) to (2-8). ７ Monovalent organic groups having 1 to 20 carbon atoms, as shown above, can be suitably used.

[0144] L Ａ The lower limit of the number of carbon atoms in the monovalent organic group represented by is preferably 2, and more preferably 3. On the other hand, the upper limit of the number of carbon atoms is preferably 10, and more preferably 8. Ａ The monovalent organic group represented by is preferably a substituted or unsubstituted hydrocarbon group, more preferably a substituted or unsubstituted linear hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group, even more preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted aralkyl group, and particularly preferably an isopropyl group or a benzyl group.

[0145] For a1, 1 and 2 are preferred, with 1 being more preferred.

[0146] For b1, an integer between 2 and 4 is preferred. By setting b1 to the above value, the proportion of metal atoms in the metal-containing compound (A) can be increased, and the generation of secondary electrons by the metal-containing compound (A) can be more effectively promoted. As a result, the rectangularity of the pattern can be improved.

[0147] As the metal compound precursor (1), a metal halide compound is preferred, and isopropyltin trichloride or benzyltin trichloride is more preferred.

[0148] A method for carrying out a hydrolysis condensation reaction with a metal compound precursor (1) includes, for example, stirring the metal compound precursor (1) in water or a water-containing solvent in the presence of a base such as tetramethylammonium hydroxide, which can be used as needed. In this case, other compounds having hydrolyzable groups may be added as needed. The lower limit of the amount of water used in this hydrolysis condensation reaction is preferably 0.2 moles, more preferably 1 mole, and even more preferably 3 moles, relative to the hydrolyzable groups present in the metal compound precursor (1). By setting the amount of water in the hydrolysis condensation reaction within the above range, a metal-containing compound (A) can be efficiently obtained.

[0149] In the synthesis reaction of the metal-containing compound (A), in addition to the metal compound precursor (1), L in the compound of formula (4) above is also present. Ａ Compounds that can act as polydentate ligands or crosslinking ligands, etc., represented by the formula, may be added. Examples of compounds that can act as crosslinking ligands include compounds having two or more coordinating groups such as hydroxyl groups, isocyanate groups, amino groups, ester groups, and amide groups.

[0150] The lower limit of the temperature for the synthesis reaction of the metal-containing compound (A) is preferably 0°C, more preferably 10°C. The upper limit of the above temperature is preferably 150°C, more preferably 100°C, and even more preferably 50°C.

[0151] The lower limit of the time for the synthesis reaction of the metal-containing compound (A) is preferably 1 minute, more preferably 10 minutes, and even more preferably 1 hour. The upper limit of the above time is preferably 100 hours, more preferably 50 hours, even more preferably 24 hours, and particularly preferably 4 hours.

[0152] (Solvent (F)) An organic solvent is preferred as solvent (F). Specific examples of this organic solvent include, for example, those similar to those exemplified as solvent [B] in the above-mentioned underlayer film-forming composition for metal-containing resist films.

[0153] As the solvent (F), an ether-based solvent is preferred, and propylene glycol monoethyl ether is more preferred.

[0154] (Other optional components) In addition to the metal-containing compound (A) and solvent (F), the metal-containing resist film forming composition may also contain other optional components such as ligands and surfactants.

[0155] (Compounds that can act as ligands) Examples of compounds that can act as ligands include compounds that can act as polydentate ligands or bridging ligands, and specifically include those similar to the compounds that can act as polydentate ligands or bridging ligands exemplified in the synthesis method of metal-containing compound (A).

[0156] (Surfactants) Surfactants are components that improve the applicability, striation, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate, as well as the following trade names: KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. Examples include 95 (Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (all from Tochem Products Co., Ltd.), Megafac F171, F173 (both from Dainippon Ink and Chemicals, Inc.), Florard FC430, FC431 (both from Sumitomo 3M Co., Ltd.), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all from Asahi Glass Co., Ltd.).

[0157] (Method for preparing a composition for forming a metal-containing resist film) A composition for forming a metal-containing resist film can be prepared, for example, by mixing a metal-containing compound (A) and a solvent (F) with other optional components in a predetermined ratio, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.4 μm or less. It is preferable that the content of the metal-containing compound (A) in the components other than the solvent (F) in the above metal-containing resist film forming composition is 50% by mass or more. The lower limit of the content of the metal-containing compound (A) is more preferably 60% by mass, and even more preferably 70% by mass. On the other hand, the upper limit of the above content is preferably 100% by mass, but may also be 98% by mass or 95% by mass.

[0158] To explain this resist film formation process in more detail, when the resist film is formed using a metal-containing resist film forming composition, for example, after coating the metal-containing resist film forming composition so that the metal-containing resist film to be formed has a predetermined thickness, the solvent in the coated film is evaporated by pre-baking (hereinafter also referred to as "PB"), thereby forming the metal-containing resist film.

[0159] The PB temperature and PB time can be appropriately determined depending on the type of metal-containing resist film forming composition used. The lower limit of the PB temperature is preferably 30°C, and more preferably 50°C. The upper limit of the PB temperature is preferably 200°C, and more preferably 150°C. The lower limit of the PB time is preferably 10 seconds, and more preferably 30 seconds. The upper limit of the PB time is preferably 600 seconds, and more preferably 300 seconds.

[0160] [Exposure Process] In this process, the resist film is exposed to radiation.

[0161] The radiation used for exposure can be appropriately selected depending on 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, electron beams or far ultraviolet light are preferred, and electron beams or KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ２Excimer laser light (wavelength 157 nm), Kr ２ Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, also known as "EUV") is more preferred, and electron beams or EUV are even more preferred. Furthermore, the exposure conditions can be appropriately determined according to the type of resist film-forming composition used, etc.

[0162] Furthermore, in this process, after exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined according to the type of resist film forming composition used. The lower limit of the PEB temperature is preferably 50°C, and more preferably 70°C. The upper limit of the PEB temperature is preferably 200°C, and more preferably 150°C. The lower limit of the PEB time is preferably 10 seconds, and more preferably 30 seconds. The upper limit of the PEB time is preferably 600 seconds, and more preferably 300 seconds.

[0163] [Development Process] In this process, at least the exposed resist film is developed. At this time, a portion of the underlying resist film may also be developed. Depending on the type of resist film forming composition, development may be by dissolution in a developer solution, by volatilization by heating or reduced pressure, or by etching. This allows a resist pattern to be formed.

[0164] Examples of developers used when employing the above-mentioned developer include alkaline aqueous solutions (alkaline developer) and organic solvent-containing solutions (organic solvent developer).

[0165] The basic solution for alkaline development is not particularly limited, and known basic solutions can be used. Examples of basic solutions for alkaline development include alkaline aqueous solutions in which at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. Among these, aqueous TMAH is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0166] Examples of organic solvent developers used in organic solvent development include those similar to those exemplified as solvent [B] above. Preferred organic solvents include ester solvents, ether solvents, alcohol solvents, ketone solvents and / or hydrocarbon solvents, with ketone solvents being more preferred, and 2-heptanone being particularly preferred.

[0167] Etching methods include dry etching and wet etching. Dry etching using hydrogen bromide or the like is preferred as the etching method.

[0168] In this process, washing and / or drying may be performed after development as described above. Furthermore, etching may be performed using the resist pattern as a mask. The above-described method can be suitably used as the etching method.

[0169] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0170] [Weight-average molecular weight (Mw), number-average molecular weight (Mn)] The Mw and Mn of the polymers were measured by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as the standard, under analytical conditions of Tosoh Corporation's GPC columns (two "G2000HXL" columns and one "G3000HXL" column), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C.

[0171] [Average film thickness] The average film thickness was determined by measuring the film thickness at nine arbitrary points at 5 cm intervals, including the center of the resist underlayer film formed on a silicon wafer (substrate), using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"). The average of these film thicknesses was then calculated.

[0172] <Synthesis of Polymer [A] and Comparative Polymer> Polymers [A] having repeating units represented by the following formulas (A-1) to (A-32) were synthesized according to the procedure shown below. A comparative polymer having repeating units represented by the following formula (CA-1) was also synthesized. In the following formulas, the numbers attached to each repeating unit indicate the content percentage (mol%) of that repeating unit. The composition ratio is １３ Confirmed via C-NMR.

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179]

[0180]

[0181] The following monomers (a1-1) to (a1-13) (hereinafter also referred to as "[a1] compound"), (a2-1) to (a2-5) (hereinafter also referred to as "[a2] compound"), (a3-1) to (a3-4) (hereinafter also referred to as "[a3] compound"), (b-1) to (b-4) (hereinafter also referred to as "[b] compound"), and (c-1) to (c-2) (hereinafter also referred to as "[c] compound"), and (d-1) to (d-2) (hereinafter also referred to as "[d] compound") were used in the synthesis of the [A] polymer and the comparative polymer.

[0182]

[0183]

[0184]

[0185]

[0186] [Synthesis Example 1-1] (Synthesis of Compound (a1-1)) 150 mL of acetonitrile, 10.62 g of methacrylic acid, 20.00 g of (1S,2S,3R,5S)-(+)-2,3-pinanediol (or (1R,2R,3S,5R)-(-)-2,3-pinanediol), and 2.87 g of 4-dimethylaminopyridine were added to a reaction vessel and stirred at room temperature until dissolved, then the mixture was placed in an ice bath. 24.77 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added, and the mixture was stirred at room temperature for 3 hours. 300 ml of diisopropyl ether was added to the reaction mixture and mixed, then washed with 100 ml of 2M hydrochloric acid aqueous solution, 100 ml of 2.5% ammonia aqueous solution, and 100 ml of saturated sodium bicarbonate solution. The organic layer was concentrated, the residue was purified by silica gel column chromatography, and crystallized on hexane to obtain the white solid compound (a1-1).

[0187] [Synthesis Example 1-2] (Synthesis of Compound (a1-2)) 150 mL of acetonitrile, 18.28 g of 4-vinylbenzoic acid, 20.00 g of (1S,2S,3R,5S)-(+)-2,3-pinanediol (or (1R,2R,3S,5R)-(-)-2,3-pinanediol), and 2.87 g of 4-dimethylaminopyridine were added to a reaction vessel and stirred at room temperature until dissolved, then the mixture was bathed in ice. 24.77 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added, and the mixture was stirred at room temperature for 3 hours. 300 ml of diisopropyl ether was added to the reaction mixture and mixed, then washed with 100 ml of 2M hydrochloric acid aqueous solution, 100 ml of 2.5% ammonia aqueous solution, and 100 ml of saturated sodium bicarbonate solution. The organic layer was concentrated, the residue was purified by silica gel column chromatography, and crystallized on hexane to obtain compound (a1-2) as a white solid.

[0188] [Synthesis Examples 1-3 to 1-12] (Synthesis of compounds (a1-3) to (a1-12)) Compounds (a1-3) to (a1-12) were synthesized in the same manner as compound (a1-1), except that the corresponding alcohol compound was used instead of (1S,2S,3R,5S)-(+)-2,3-pinanediol.

[0189] [Synthesis Example 1-13] (Synthesis of Compound (a1-13)) Compound (a1-13) was synthesized in the same manner as compound (a1-1), except that 2-(2-(((2-hydroxy-2,6,6-trimethylbicyclo[3.1.1]heptan-3-yl)oxy)carbonyl)-4-vinylphenoxy)acetic acid was used instead of 4-vinylbenzoic acid.

[0190] [Synthesis Examples 2-1, 2-3 to 2-5] (Synthesis of compound (a2-1)) Compounds (a2-1), (a2-3) to (a2-5) were synthesized in the same manner as compound (a1-1), except that the corresponding alcohol compound was used instead of (1S,2S,3R,5S)-(+)-2,3-pinanediol.

[0191] [Synthesis Example 2-2] (Synthesis of Compound (a2-2)) 20 mL of water and 20.00 g of methyl [(3,4-epoxycyclohexane)-1-yl]methyl methacrylate were added to a reaction vessel and stirred at 60°C for 4 hours. 100 mL of ethyl acetate was added to the aqueous solution after the reaction and stirred, and the aqueous layer was removed. The extraction procedure was repeated twice from the removed aqueous layer, and the resulting organic layers were combined and concentrated. The residue was purified by silica gel column chromatography to obtain compound (a2-2) as a colorless liquid.

[0192] [Synthesis Example 3-1] (Synthesis of Compound (a3-1)) 200 mL of dichloromethane, 20.00 g of 1,3-bis(α-hydroxyisopropyl)benzene, and 15.63 g of triethylamine were added to a reaction vessel and stirred at room temperature until dissolved, then the mixture was bathed in ice. 12.92 g of methacrylate chloride was added, and the mixture was stirred at room temperature for 3 hours. The reaction mixture was washed with 100 ml of saturated ammonium chloride aqueous solution, 100 ml of 2.5% ammonia aqueous solution, and 100 ml of saturated sodium bicarbonate aqueous solution. The organic layer was concentrated, and the residue was purified by silica gel column chromatography to obtain compound (a3-1) as a colorless liquid.

[0193] [Synthesis Example 3-2] (Synthesis of Compound (a3-2)) 150 mL of tetrahydrofuran, 20.00 g of 4-(3-acetylphenyl)propane-2-yl methacrylate, and 21.00 g of anhydrous cerium(III) chloride were added to a reaction vessel and stirred at room temperature for 10 minutes, then bathed in ice. 12.32 ml of ethylmagnesium bromide (13% tetrahydrofuran solution) was added dropwise, and the mixture was stirred at room temperature for 3 hours. The reaction mixture was washed with 100 ml of saturated ammonium chloride aqueous solution and 100 ml of pure water. The organic layer was concentrated, and the residue was purified by silica gel column chromatography to obtain compound (a3-2) as a colorless liquid.

[0194] [Synthesis Example 3-3] (Synthesis of Compound (a3-3)) 300 mL of tetrahydrofuran and 20.00 g of 4-vinylbenzaldehyde were added to a reaction vessel and stirred at room temperature for 10 minutes, then the mixture was placed in an ice bath. 6.65 ml of methylmagnesium bromide (12% tetrahydrofuran solution) was added dropwise, and the mixture was stirred at room temperature for 3 hours. 600 ml of diisopropyl ether was added to the reaction mixture and washed with 300 ml of 2 M hydrochloric acid aqueous solution and 300 ml of pure water. After concentrating the organic layer, the residue was purified by vacuum distillation to obtain compound (a3-3) as a colorless liquid.

[0195] [Synthesis Example 3-4] (Synthesis of Compound (a3-4)) 300 mL of tetrahydrofuran and 20.00 g of 4-vinylbenzaldehyde were added to a reaction vessel and stirred at room temperature for 10 minutes, then bathed in ice. 6.65 ml of ethylmagnesium bromide (13% tetrahydrofuran solution) was added dropwise, and the mixture was stirred at room temperature for 3 hours. 600 ml of diisopropyl ether was added to the reaction mixture and washed with 300 ml of 2 M hydrochloric acid aqueous solution and 300 ml of pure water. After concentrating the organic layer, the residue was purified by vacuum distillation to obtain compound (a3-4) as a colorless liquid.

[0196] [Synthesis Example 2-1] (Synthesis of Polymer (A-1)) 6 g of 4-methyl-2-pentanone was placed in a reaction vessel and maintained at 80°C. A mixture of 2.03 g of compound (a1-1), 3.97 g of compound (c-1), 1.35 g of dimethyl-2,2-azobis(2-methylpropionate), and 12.00 g of 4-methyl-2-pentanone was added dropwise from a feeder over 3 hours. The mixture was then stirred at 80°C for 3 hours. The resulting polymerization solution was precipitated and purified with five times the volume of heptane to obtain 5.5 g of polymer (A-1) as a white solid.

[0197] [Synthesis Examples 2-2 to 2-32 and Comparative Synthesis Example 2-1] (Synthesis of Polymers (A-2) to (A-32) and Comparative Polymer (CA-1)) Polymers (A-2) to (A-32) and comparative polymer (CA-1) were synthesized in the same manner as polymer (A-1), except that the types and amounts of compound [a], compound [b], compound [c], and compound [d] shown in Table 1 were used. The Mw and Mn of the obtained polymers [A] and comparative polymer (CA-1) are also shown in Table 1. In the table, "-" indicates that the corresponding component was not used. The same applies to the following tables.

[0198]

[0199] <Preparation of composition for forming a resist underlayer film> The following describes the polymers, solvents, comparative polymers (CA-1), acid generators, crosslinking agents, and additives used in the preparation of the composition for forming a resist underlayer film (hereinafter also referred to as "the composition").

[0200] [A Polymer] A-1 to A-32: The polymers synthesized above (A-1) to (A-32)

[0201] [Comparative Polymer (CA-1)] CA-1: The polymer synthesized above (CA-1)

[0202] [B Solvent] B-1: Propylene glycol monomethyl ether acetate B-2: Propylene glycol monomethyl ether

[0203] [C] Acid Generators C-1: Compound represented by the following formula (C-1) C-2: Compound represented by the following formula (C-2) C-3: Compound represented by the following formula (C-3)

[0204]

[0205] [D] Crosslinking agent: D-1: Compound represented by the following formula (D-1)

[0206]

[0207] [E] Additives E-1: Compound represented by the following formula (E-1) E-2: Compound represented by the following formula (E-2) E-3: Compound represented by the following formula (E-3) E-4: Compound represented by the following formula (E-4) E-5: Compound represented by the following formula (E-5) E-6: Compound represented by the following formula (E-6)

[0208]

[0209] [Example 1-1] [A] 100 parts by mass of (A-1) as a polymer was dissolved in [B] 6,000 parts by mass of (B-1) and 14,000 parts by mass of (B-2) as solvents. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0210] [Examples 1-2 to 1-40 and Comparative Example 1-1] Compositions (J-2) to (J-40) and (CJ-1) were prepared in the same manner as in Example 1-1, except that the components used were of the types and in the amounts shown in Table 2 below.

[0211]

[0212] <Evaluation> Using the compositions prepared above, the rectangularity of the resist patterns obtained by EUV exposure using the metal-containing resist film formation composition (hereinafter also referred to as "resist composition") was evaluated by the following method. The evaluation results are shown in Tables 3 and 4 below.

[0213] <Preparation of Resist Composition (R-1)> Compound (S-1) used in the preparation of resist composition (R-1) was synthesized by the following procedure. In a reaction vessel, 6.5 parts by mass of isopropyltin trichloride was added while stirring 150 mL of 0.5 N aqueous sodium hydroxide solution, and the mixture was stirred for 2 hours. The precipitated material was filtered off, washed twice with 50 parts by mass of water, and then dried to obtain compound (S-1). Compound (S-1) is the oxidized hydroxide product (i-PrSnO) of the hydrolysis product of isopropyltin trichloride. （３／２-ｘ／２） (OH) ｘ (The structural units were defined as 0 < x < 3).

[0214] Two parts by mass of the synthesized compound (S-1) were mixed with 98 parts by mass of propylene glycol monoethyl ether. The resulting mixture was then filtered to remove residual water using an activated 4 Å molecular sieve, and then filtered through a 0.2 μm pore size filter to prepare the resist composition (R-1).

[0215] [Rectangular Resist Pattern (EUV Exposure; Organic Solvent Development)] An organic underlayer film with an average thickness of 100 nm was formed on a 12-inch silicon wafer by applying an organic underlayer film formation material (HM8006 from JSR Corporation) using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited) by rotary coating, followed by heating at 250°C for 60 seconds. The above-prepared resist underlayer film formation composition was applied to this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film with an average thickness of 5 nm. A resist composition (R-1) was applied to this resist underlayer film by rotary coating using the above-prepared spin coater, and after a predetermined time had elapsed, heated at 90°C for 60 seconds and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 35 nm. The resist film was exposed using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadruple pole illumination, wafer-mounted 1:1 line-and-space mask with a line width of 16 nm)). After exposure, the substrate was heated at 110°C for 60 seconds, then cooled at 23°C for 60 seconds. Subsequently, it was developed using the paddle method with 2-heptanone (20-25°C) and dried to obtain an evaluation substrate with a resist pattern formed on it. A scanning electron microscope (Hitachi High-Tech Corporation's "CG-6300") was used to measure and observe the resist pattern on the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) if the cross-sectional shape of the pattern was rectangular, and "B" (poor) if there was a hem in the cross-section of the pattern.

[0216]

[0217] [Rectangular Resist Pattern (EUV Exposure; Dry Etching Development)] An organic underlayer film formation material (HM8006 from JSR Corporation) was applied to a 12-inch silicon wafer by a rotary coating method using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. The resist underlayer film formation composition prepared above was applied to this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film with an average thickness of 5 nm. The resist composition (R-1) was applied to this resist underlayer film by a rotary coating method using the spin coater, and after a predetermined time had elapsed, heated at 90°C for 60 seconds and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 35 nm. The resist film was exposed using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadruple pole illumination, wafer-mounted 1:1 line-and-space mask with a line width of 16 nm)). After exposure, the substrate was heated at 110°C for 60 seconds, then cooled at 23°C for 60 seconds. Subsequently, an evaluation substrate with a resist pattern was obtained by developing it with hydrogen bromide. A scanning electron microscope (Hitachi High-Tech Corporation's "CG-6300") was used to measure and observe the resist pattern on the evaluation substrate. The rectangularity of the resist pattern was evaluated as "A" (good) if the cross-sectional shape of the pattern was rectangular, and "B" (poor) if there was a drooping edge in the cross-section of the pattern.

[0218]

[0219] As can be seen from the results in Tables 3 and 4, the resist underlayer film formed from the composition of the example showed superior resist pattern rectangularity compared to the resist underlayer film formed from the composition of the comparative example.

[0220] The resist underlayer film formation composition of the present invention makes it possible to form a film with excellent resist pattern rectangularity. The semiconductor substrate manufacturing method of the present invention uses a resist underlayer film formation composition capable of forming a resist underlayer film with excellent resist pattern rectangularity, thus enabling efficient manufacturing of semiconductor substrates. Therefore, these can be suitably used in the manufacture of semiconductor devices and the like.

Claims

Polymers and solvent and It contains, A resist underlayer film forming composition wherein the polymer has a group containing at least one hydroxyl group selected from the group consisting of the following formulas (A1) to (A4). (In the above formulas (A1) to (A4), R ａ１ , R ａ２ and R ｂ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ａ１ and R ｂ These atoms can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the two carbon atoms to which they are bonded. R ｃ and R ｄ are each independently a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ｃ and R ｄ are combined with each other to form a ring structure having 3 to 20 carbon atoms together with the carbon atoms to which they are attached. Ar １ This is a substituted or unsubstituted divalent aromatic ring having 3 to 20 carbon atoms. R ｅ and R ｆ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a hydrogen atom. However, R ｅ and R ｆ At least one of them is a hydrogen atom. Cy １ This is a ring structure with 3 to 20 members, formed together with the two carbon atoms in formula (A3). Ar ２ This is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. Cy ２ Ar ２ It is a substituted or unsubstituted alicyclic ring with 4 to 20 carbon atoms, formed together with the two carbon atoms in formula (A4) that constitute the aromatic ring. However, at least one hydrogen atom is bonded to at least one carbon atom at the β position of the oxygen atom of OH in formula (A4). * indicates a bonding site with other parts of the polymer described above. 　 The resist underlayer film forming composition according to claim 1, wherein the polymer has repeating units represented by the following formula (1). (In the above formula (1), R ０ This is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, either substituted or unsubstituted. L １ This is a 1+n valence linking group or single bond. X is a group containing the hydroxyl group described above. 　 n is an integer between 1 and 5. If n is 2 or greater, multiple X values ​​are either identical or distinct from each other. 　 The polymer composition for forming a resist underlayer film according to claim 1 or claim 2 further has a repeating unit represented by the following formula (2). (In formula (2), R ３Ａ This is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, either substituted or unsubstituted. L ３Ａ It is a single bond or a divalent linking group. R ４Ａ (This group is selected from the group consisting of groups represented by any of the following formulas (2-1) to (2-8).) (In formulas (2-1) to (2-3), (2-7), R ８Ａ , R ９Ａ , R １０Ａ , R １２Ａ and R １３Ａ Each of these is independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (2-2), Cy is a ring structure with 3 to 20 members, formed together with the two carbon atoms in the formula. １１Ａ is a hydrogen atom, a monovalent organic group with 1 to 20 carbon atoms, or a single bond. ** is a bond with an atom constituting Cy. However, R １１Ａ If it is a single bond, １１Ａ It combines with **. In equations (2-1) to (2-8), R ７Ａ * is a divalent organic group or single bond having 1 to 20 carbon atoms. ３Ａ (This is a bonding bond with the constituent atoms.) 　 A composition for forming an underlayer of a resist film that is subjected to exposure with extreme ultraviolet light, as described in claim 1 or claim 2. 　 The resist underlayer film forming composition according to claim 4, wherein the resist film contains a metal. 　 The resist film is formed by a metal-containing resist film forming composition, the metal-containing resist film forming composition contains a metal-containing compound and a solvent, and the proportion of the metal-containing compound in the metal-containing resist film forming composition other than the solvent is 50% by mass or more, according to claim 5, for forming a resist underlayer film. 　 The resist underlayer film forming composition according to claim 1 or claim 2, which is a composition for forming a resist underlayer film with a film thickness of 5 nm or less. 　 A step of coating a resist underlayer film formation composition directly or indirectly onto a substrate, A step of forming a resist film on the resist underlayer film formed by the above resist underlayer film formation composition coating step, The process involves exposing the above-mentioned resist film with radiation, At least the process of developing the exposed resist film and Includes, The above resist underlayer film forming composition, Polymers and, solvent and It contains, A method for producing a semiconductor substrate, wherein the polymer has a group containing at least one hydroxyl group selected from the group consisting of the following formulas (A1) to (A4). (In the above formulas (A1) to (A4), R ａ１ , R ａ２ and R ｂ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ａ１ and R ｂ These atoms can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the two carbon atoms to which they are bonded. R ｃ and R ｄ Each of these is independently either a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom, or R ｃ and R ｄ These can be combined with each other to form a ring structure with 3 to 20 carbon atoms, along with the carbon atoms to which they are bonded. Ar １ This is a substituted or unsubstituted divalent aromatic ring having 3 to 20 carbon atoms. R ｅ and R ｆ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a hydrogen atom. However, R ｅ and R ｆ At least one of them is a hydrogen atom. Cy １ This is a ring structure with 3 to 20 members, formed together with the two carbon atoms in formula (A3). Ar ２ This is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. Cy ２ Ar ２ It is a substituted or unsubstituted alicyclic ring with 4 to 20 carbon atoms, formed together with the two carbon atoms in formula (A4) that constitute the aromatic ring. However, at least one hydrogen atom is bonded to at least one carbon atom at the β position of the oxygen atom of OH in formula (A4). * indicates a bonding site with other parts of the polymer described above. 　 The method for manufacturing a semiconductor substrate according to claim 8, wherein the resist film is formed by a metal-containing resist film forming composition, the metal-containing resist film forming composition contains a metal-containing compound and a solvent, and the proportion of the metal-containing compound in the metal-containing resist film forming composition other than the solvent is 50% by mass or more. 　 A method for manufacturing a semiconductor substrate according to claim 8 or claim 9, wherein the radiation is extreme ultraviolet light. 　 The method for manufacturing a semiconductor substrate according to claim 8 or claim 9, wherein the thickness of the resist underlayer film is 5 nm or less.

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