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

Abstract

Provided are: a resist underlayer film-forming composition capable of forming a resist underlayer film having excellent properties for suppressing resist pattern collapse; and a method for producing a semiconductor substrate. This resist underlayer film-forming composition contains a solvent and a polysiloxane having a first structural unit represented by formula (1). (In formula (1), X represents a monovalent group represented by formula (1-1). a represents an integer of 1-3. When a is 2 or more, the plurality of X's are identical or different from each other. R1 represents a monovalent organic group having 1-20 carbon atoms, a hydroxy group, or a halogen atom. b represents an integer of 0-2. When b is 2, the two R1s are identical or different from each other. Here, a+b is 3 or less.)　

Description

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

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

[0002] For pattern formation in the manufacture of semiconductor substrates, for example, a multilayer resist process is used in which a resist film laminated on a substrate via an organic underlayer film, a resist underlayer film, etc. is exposed and developed, and the resulting resist pattern is used as a mask to perform etching to form a patterned substrate (see WO 2012 / 039337 ).

[0003] International Publication No. 2012 / 039337

[0004] In recent years, semiconductor devices have become increasingly highly integrated, and the exposure light used has tended to be shorter in wavelength, moving from KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) to extreme ultraviolet (13.5 nm, hereinafter also referred to as "EUV").

[0005] As the line width of resist patterns formed by exposure to extreme ultraviolet light and development continues to become finer, resist underlayer films are required to be able to suppress the collapse of resist patterns.

[0006] An object of the present invention is to provide a composition for forming a resist underlayer film that can form a resist underlayer film that has excellent properties for suppressing collapse of a resist pattern, and a method for producing a semiconductor substrate.

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0008] In one embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a polysiloxane having a first structural unit represented by the following formula (1); and a solvent. (In the above formula (1), X is a monovalent group represented by the following formula (1-1). a is an integer of 1 to 3. When a is 2 or more, multiple Xs may be the same or different. R １is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. b is an integer of 0 to 2. When b is 2, two R １ are the same or different, provided that a + b is 3 or less.) (In the above formula (1-1), L １ is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. * is a bond to the silicon atom in the above formula (1). (i) R ２ and R ３ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, or (ii) R ２ is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ３ and R ４ represent a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which is bonded to each other together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom, or (iii) R ２ ~R ４ represent a trivalent alicyclic hydrocarbon group having 5 to 20 carbon atoms which is bonded to each other and constituted together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom.

[0009] The resist underlayer film-forming composition contains a polysiloxane having a tertiary carbon atom or a quaternary carbon atom (hereinafter also referred to as "tertiary carbon atom, etc.") in the substituent of the first structural unit. This allows for the formation of a resist underlayer film with excellent resist pattern collapse suppression properties (hereinafter also referred to as "pattern collapse suppression properties"). While the reason for this is unclear, it is presumed to be as follows. Typically, polysiloxanes are produced by a hydrolysis condensation reaction between silanol groups generated by hydrolysis of hydrolyzable groups. During this process, the hydrolysis condensation reaction is partially inhibited by the bulky substituent having a tertiary carbon atom, etc., introduced into the polysiloxane, leaving a certain amount of silanol groups remaining. As a result, it is presumed that an interaction occurs between the silanol groups of the resist underlayer film and the resist film formed thereon, resulting in excellent pattern collapse suppression properties.

[0010] In another embodiment, the present invention relates to a method for manufacturing a semiconductor substrate, comprising: a step of applying the composition for forming a resist underlayer film directly or indirectly to a substrate to form a resist underlayer film; a step of applying the composition for forming a resist film directly or indirectly to the resist underlayer film to form a resist film; a step of exposing the resist film to radiation; and a step of developing the exposed resist film to form a resist pattern.

[0011] In this production method, the composition for forming a resist underlayer film is used to form a resist underlayer film as an underlayer of a resist film, and a resist underlayer film having excellent pattern collapse suppression properties can be formed, so that high-quality semiconductor substrates can be efficiently produced.

[0012] As used herein, "polysiloxane" refers to a compound containing a siloxane bond (-Si-O-Si-). A "tertiary carbon atom" refers to a carbon atom to which three carbon atoms are bonded, and a "quaternary carbon atom" refers to a carbon atom to which four carbon atoms are bonded. An "organic group" refers to a group containing at least one carbon atom. A "bridged ring" refers to a polycyclic structure in which two or more non-adjacent carbon atoms that form a ring are linked by a linking group. A "bridgehead" refers to a carbon atom in a bridged ring to which a linking group is bonded.

[0013] The composition for forming a resist underlayer film and the method for producing a semiconductor substrate according to the embodiments of the present invention will be described in detail below.

[0014] <Composition for forming a resist underlayer film> The composition for forming a resist underlayer film according to this embodiment contains a polysiloxane having a group having a tertiary carbon atom or the like incorporated therein and a solvent. The composition may contain other optional components (hereinafter also simply referred to as "optional components") within a range that does not impair the effects of the present invention.

[0015] [Polysiloxane] The composition for forming a resist underlayer film contains a polysiloxane having a predetermined first structural unit. The composition for forming a resist underlayer film may contain one or more types of polysiloxane. The polysiloxane may contain structural units other than the first structural unit (hereinafter simply referred to as "other structural units"), as long as the effects of the present invention are not impaired. Each structural unit contained in the polysiloxane will be described below.

[0016] (First structural unit) The first structural unit is represented by the following formula (1). The polysiloxane can have one or more types of first structural units. The first structural unit has a group having a tertiary carbon atom or the like represented by X in the following formula (1), so that a resist underlayer film having excellent pattern collapse suppression properties can be formed.

[0017] (In the above formula (1), X is a monovalent group represented by the following formula (1-1). a is an integer of 1 to 3. When a is 2 or more, multiple Xs may be the same or different. R １ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. b is an integer of 0 to 2. When b is 2, two R １ are the same or different, provided that a + b is 3 or less.) (In the above formula (1-1), L １ is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. * is a bond to the silicon atom in the above formula (1). (i) R ２ and R ３are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, or (ii) R ２ is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ３ and R ４ represent a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which is bonded to each other together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom, or (iii) R ２ ~R ４ represent a trivalent alicyclic hydrocarbon group having 5 to 20 carbon atoms which is bonded to each other and constituted together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom.

[0018] In the above formula (1), R １ Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing linking group between the carbon-carbon bond of this hydrocarbon group (hereinafter also referred to as "group (α)"), a group in which some or all of the hydrogen atoms in the hydrocarbon group or the group (α) have been substituted with monovalent heteroatom-containing substituents (hereinafter also referred to as "group (β)"), and a group in which the hydrocarbon group, the group (α) or the group (β) is combined with a divalent heteroatom-containing linking group (hereinafter also referred to as "group (γ)").

[0019] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

[0020] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, isobutyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0021] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group; polycyclic alicyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group and a tetracyclododecyl group; monocyclic alicyclic unsaturated hydrocarbon groups such as a cyclopentenyl group and a cyclohexenyl group; and polycyclic alicyclic unsaturated hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group and a tetracyclododecenyl group.

[0022] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

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

[0024] Examples of the divalent heteroatom-containing linking group include -O-, -C(=O)-, -S-, -C(=S)-, -NR'-, and -SO ２ -, a group consisting of two or more of these, etc. R' is a hydrogen atom or a monovalent hydrocarbon group.

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

[0026] R １ Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0027] b is preferably 0 or 1, and more preferably 0.

[0028] In the above formula (1-1), L １ The divalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (1) is R１ Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown in the above, groups in which one hydrogen atom has been removed from groups corresponding to 1 to 10 carbon atoms can be preferably used. １ The divalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) is preferably a divalent chain hydrocarbon group having 1 to 10 carbon atoms, more preferably an alkanediyl group having 1 to 8 carbon atoms, still more preferably an alkanediyl group having 1 to 6 carbon atoms, and particularly preferably a methylene group, an ethylene group, a 1,3-propanediyl group, a 2-methyl-1,3-propanediyl group, a 2-ethyl-1,3-propanediyl group, a 1,4-butanediyl group, a 3-methyl-1,4-butanediyl group, or a 3-ethyl-1,4-butanediyl group.

[0029] In the above formula (1-1), L １ is preferably a single bond, a methylene group, an ethylene group or a 1,3-propanediyl group, and more preferably a single bond.

[0030] In the above formula (1-1), R ２ ~R ３ The monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (1) is R １ Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms in the above formula, groups corresponding to 1 to 10 carbon atoms can be suitably used.

[0031] In the above formula (1-1), R ２ ~R ３ Examples of the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include groups in which some or all of the hydrogen atoms in the monovalent hydrocarbon group having 1 to 10 carbon atoms have been substituted with halogen atoms. As the halogen atom, a fluorine atom or an iodine atom is preferred, and an iodine atom is more preferred.

[0032] In the above formula (1-1), R ４ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is １ A monovalent hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0033] In the above formula (1-1), R ３ and R ４As a divalent alicyclic hydrocarbon having 3 to 20 carbon atoms which is formed by bonding together with the carbon atoms to which they are bonded, R １ A group in which one hydrogen atom has been removed from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0034] R ３ and R ４ The halogen atom in the group in which the divalent alicyclic hydrocarbon group formed by the formula (I) is substituted with a halogen atom is preferably a fluorine atom or an iodine atom, and more preferably an iodine atom.

[0035] In the above formula (1-1), R ２ ~R ４ Examples of the trivalent alicyclic hydrocarbon group having 5 to 20 carbon atoms which is formed by bonding together with the carbon atoms to which they are bonded include a bridged alicyclic hydrocarbon group in which C in the above formula (1-1) is a bridgehead carbon. Specific examples of the bridged alicyclic hydrocarbon group include a 1-norbornyl group and a 1-adamantyl group.

[0036] R ２ ~R ４ The halogen atom in the group in which the trivalent alicyclic hydrocarbon group formed by the formula (I) is substituted with a halogen atom is preferably a fluorine atom or an iodine atom, and more preferably an iodine atom.

[0037] In the above formula (1-1), R ２ ~R ４ are each independently preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, further preferably an alkyl group having 1 to 8 carbon atoms, and particularly preferably an alkyl group having 1 to 6 carbon atoms.

[0038] Specific examples of X in the above formula (1) include structures represented by the following formulas (1-1-1) to (1-1-114) (including Si in the above formula (1)).

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] The lower limit of the content of the first structural unit in all structural units constituting the polysiloxane is preferably 0.5 mol%, more preferably 1 mol%, even more preferably 4 mol%, and particularly preferably 6 mol%. The upper limit of the content of the first structural unit is preferably 70 mol%, more preferably 60 mol%, even more preferably 50 mol%, and particularly preferably 40 mol%. By ensuring that the content of the first structural unit is within the above range, a resist underlayer film having excellent pattern collapse suppression properties can be efficiently formed.

[0047] (Second structural unit) The polysiloxane preferably has a second structural unit represented by the following formula (2) as a structural unit other than the first structural unit: When the polysiloxane has the second structural unit, the oxygen gas etching resistance of the resist underlayer film formed from the composition for forming a resist underlayer film can be improved.

[0048] (In the above formula (2), Y is a substituted or unsubstituted monovalent alkoxy group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. c is an integer of 0 to 3. When c is 2 or more, multiple Ys are the same or different.)

[0049] In the above formula (2), specific examples of the monovalent alkoxy group having 1 to 20 carbon atoms represented by Y include alkoxy groups such as methoxy, ethoxy, n-propyloxy, and isopropyloxy. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms.

[0050] In the above formula (2), Y is preferably an alkoxy group, more preferably a methoxy group.

[0051] When the polysiloxane contains the second structural unit, the lower limit of the content of the second structural unit relative to all structural units constituting the polysiloxane is preferably 20 mol%, more preferably 30 mol%, and even more preferably 35 mol%, and the upper limit of the content of the second structural unit is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%.

[0052] (Third Structural Unit) The polysiloxane may have a third structural unit represented by the following formula (3) as a structural unit other than the first structural unit: By having the third structural unit, the ability of the resist underlayer film to suppress pattern collapse can be improved.

[0053] (In the above formula (3), Z is a monovalent heteroatom-containing group having 1 to 20 carbon atoms and containing at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom. d is an integer of 1 to 3. When d is 2 or more, multiple Zs may be the same or different. R ４ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. e is an integer of 0 to 2. When e is 2, two R １ are the same or different, provided that d+e is 3 or less.

[0054] In the above formula (3), examples of the monovalent heteroatom-containing group having 1 to 20 carbon atoms represented by Z include a group containing a divalent heteroatom-containing linking group between two carbon atoms of a monovalent hydrocarbon group having 1 to 20 carbon atoms (hereinafter also referred to as "group (g)"), a group in which some or all of the hydrogen atoms in the above group (g) have been substituted with monovalent heteroatom-containing substituents (hereinafter also referred to as "group (h)"), or a group combining these.

[0055] The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by Z is R １The monovalent hydrocarbon group having 1 to 20 carbon atoms as represented by the formula (I) can be suitably employed. As the monovalent hydrocarbon group having 1 to 20 carbon atoms as represented by Z, a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a combination thereof is preferred, and an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or a combination thereof is more preferred.

[0056] The divalent heteroatom-containing linking group in Z is R １ The divalent heteroatom-containing linking group in the formula (I) can be suitably used.

[0057] The monovalent heteroatom-containing substituent in Z is R in the above formula (1). １ The monovalent heteroatom-containing substituents in the above formula (I) can be suitably employed.

[0058] Specific examples of the heteroatom contained in Z include an ether bond, a thioether bond, an ester bond, a carbonate bond, an amide bond, an epoxy structure, an acetal structure, a cyano group, and combinations thereof. Z in the above formula (3) is formed by introducing such a bond or structure into the above-mentioned monovalent hydrocarbon group having 1 to 20 carbon atoms, whether linear or cyclic. Among these, specific examples of the heteroatom contained in Z include an ether bond, a thioether bond, an epoxy structure, a cyano group, and combinations thereof.

[0059] R ４ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (1) is R １ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0060] d is preferably 1 or 2, and more preferably 1.

[0061] e is preferably 0 or 1, and more preferably 0.

[0062] Specific examples of Z in the above formula (3) include structures represented by the following formulas (3-1) to (3-14) (including Si in the above formula (1)).

[0063]

[0064] When the polysiloxane contains a third structural unit, the lower limit of the content of the third structural unit in all structural units constituting the polysiloxane is preferably 1 mol%, more preferably 4 mol%, and even more preferably 8 mol%, and the upper limit of the content of the second structural unit is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0065] The lower limit of the content of the polysiloxane in the composition for forming a resist underlayer film (the total content when multiple types of polysiloxanes are contained) is preferably 0.05 mass %, more preferably 0.1 mass %, and even more preferably 0.15 mass %, based on all components contained in the composition for forming a resist underlayer film. The upper limit of the content is preferably 5 mass %, more preferably 2 mass %, and even more preferably 1 mass %.

[0066] The polysiloxane is preferably in the form of a polymer. In this specification, the term "polymer" refers to a compound having two or more structural units, and when two or more identical structural units are consecutive in a polymer, this structural unit is also referred to as a "repeating unit." When the polysiloxane is in the form of a polymer, the lower limit of the polystyrene-equivalent weight average molecular weight (Mw) of the polysiloxane measured by gel permeation chromatography (GPC) is preferably 1,000, more preferably 1,100, and even more preferably 1,200. The upper limit of the Mw is preferably 10,000, more preferably 5,000, and even more preferably 2,500. The method for measuring the Mw of the polysiloxane is as described in the Examples.

[0067] [Method of Synthesizing Polysiloxane] Polysiloxane can be synthesized by a conventional method using monomers that provide each structural unit. For example, a monomer that provides the first structural unit and, if necessary, monomers that provide other structural units can be hydrolyzed and condensed in a solvent in the presence of a catalyst such as oxalic acid and water, and the solution containing the resulting hydrolysis and condensation product can then be purified by solvent substitution or the like in the presence of a dehydrating agent such as trimethyl orthoformate. It is believed that each monomer is incorporated into the polysiloxane regardless of its type through the hydrolysis and condensation reaction or the like. Therefore, the content ratio of the first structural unit and other structural units in the synthesized polysiloxane is usually equivalent to the ratio of the amounts of each monomer used in the synthesis reaction.

[0068] Impurities can be removed by extracting the synthesized polysiloxane with water or an organic solvent. The water or organic solvent used here is preferably a combination that separates the polysiloxane into two layers, one that dissolves the polysiloxane and one that dissolves the impurities. Examples of organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, tetrahydrofuran, toluene, hexane, heptane, ethyl acetate, cyclohexanone, methyl amyl ketone, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, t-butyl acetate, t-butyl propionate, propylene glycol mono-t-butyl ether acetate, γ-butyrolactone, methyl isobutyl ketone, cyclopentyl methyl ether, acetonitrile, and mixtures thereof. When removing acid as an impurity, a combination of water and an organic solvent is preferred. It is also possible to separate and remove highly hydrophilic and highly hydrophobic components from the synthesized polysiloxane. When removing highly hydrophilic polysiloxanes, a combination of water and an organic solvent is preferred. When removing highly hydrophobic polysiloxanes, a combination of an alcohol solvent such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, or 2-methyl-1-propanol with a hydrocarbon solvent such as toluene, hexane, or heptane is preferred.

[0069] [Solvent] The solvent is not particularly limited, and examples thereof include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, nitrogen-containing solvents, hydrocarbon-based solvents, water, etc. The composition for forming a resist underlayer film may contain one or more solvents.

[0070] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, and iso-butanol, and polyalcohol solvents such as ethylene glycol, 1,2-propylene glycol, diethylene glycol, and dipropylene glycol.

[0071] Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-butyl ketone, and cyclohexanone.

[0072] Examples of ether solvents include ethyl ether, isopropyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and tetrahydrofuran.

[0073] Examples of ester solvents include ethyl acetate, γ-butyrolactone, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, ethyl propionate, n-butyl propionate, methyl lactate, and ethyl lactate.

[0074] Examples of nitrogen-containing solvents include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0075] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms, such as n-pentane and n-hexane; and aromatic hydrocarbon solvents having 6 to 16 carbon atoms, such as toluene and xylene.

[0076] Among these, ether-based solvents or ester-based solvents are preferred, and ether-based solvents or ester-based solvents having a glycol structure are more preferred because of their excellent film-forming properties.

[0077] Examples of ether-based solvents and ester-based solvents having a glycol structure include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, etc. Among these, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and propylene glycol monoethyl ether are preferred.

[0078] The lower limit of the content of the solvent in the composition for forming a resist underlayer film is preferably 90 mass %, more preferably 92.5 mass %, and even more preferably 94 mass %, based on all components contained in the composition for forming a resist underlayer film, and the upper limit of the content is preferably 99.9 mass %, more preferably 99.5 mass %, and even more preferably 99 mass %.

[0079] (Optional Components) Examples of the optional components include a photoacid generator, a basic compound (including a base generator), an acid diffusion controller, a radical generator, a surfactant, colloidal silica, colloidal alumina, an organic polymer, etc. The composition for forming a resist underlayer film may contain one or more optional components.

[0080] When the composition for forming a resist underlayer film contains an optional component, the content of the optional component in the composition for forming a resist underlayer film can be appropriately determined depending on the type of the optional component used, and within a range that does not impair the effects of the present invention.

[0081] <Method for preparing composition for forming resist underlayer film> The method for preparing the composition for forming resist underlayer film is not particularly limited, and the composition can be prepared according to a conventional method. For example, the composition can be prepared by mixing a polysiloxane solution, a solvent, and, if necessary, optional components in a predetermined ratio, and preferably filtering the resulting mixed solution through a filter having a pore size of 0.2 μm or less.

[0082] <Method for manufacturing semiconductor substrate> The method for manufacturing a semiconductor substrate according to this embodiment includes the steps of: applying a composition for forming a resist underlayer film directly or indirectly to a substrate to form a resist underlayer film (hereinafter also referred to as a "resist underlayer film forming step"); applying a composition for forming a resist film directly or indirectly to the resist underlayer film to form a resist film (hereinafter also referred to as a "resist film forming step"); exposing the resist film to radiation (hereinafter also referred to as an "exposure step"); and developing the exposed resist film to form a resist pattern (hereinafter also referred to as a "development step"). In the resist underlayer film forming step, the above-described composition for forming a resist underlayer film is used as the composition for forming a resist underlayer film.

[0083] The method for manufacturing a semiconductor substrate may further include, as necessary, a step of forming an organic underlayer film directly or indirectly on the substrate (hereinafter also referred to as an "organic underlayer film forming step") prior to the resist underlayer film forming step.

[0084] Furthermore, after the developing step, the method may further include a step of etching the resist underlayer film using the resist pattern as a mask to form a resist underlayer film pattern (hereinafter also referred to as a "resist underlayer film pattern forming step"); a step of etching using the resist underlayer film pattern as a mask (hereinafter referred to as an "etching step"); and a step of removing the resist underlayer film pattern with a basic liquid (hereinafter referred to as a "removing step").

[0085] According to the method for manufacturing a semiconductor substrate, by using the above-mentioned composition for forming a resist underlayer film as the composition for forming a resist underlayer film in the resist underlayer film-forming composition application step, a resist pattern with excellent pattern collapse suppression properties can be formed on the resist underlayer film.

[0086] Hereinafter, each step included in the method for manufacturing a semiconductor substrate will be described, including an organic underlayer film forming step prior to the resist underlayer film forming step, and a resist underlayer film pattern forming step, etching step, and removal step after the development step.

[0087] [Organic Underlayer Film Formation Step] In this step, an organic underlayer film is formed directly or indirectly on the substrate prior to the resist underlayer film formation step. This step is an optional step. By this step, an organic underlayer film is formed directly or indirectly on the substrate.

[0088] The organic underlayer film can be formed by coating an organic underlayer film-forming composition, etc. Examples of methods for forming an organic underlayer film by coating an organic underlayer film-forming composition include a method in which the organic underlayer film-forming composition is directly or indirectly applied to a substrate, and the resulting coating film is heated or exposed to light to cure it. Examples of the organic underlayer film-forming composition that can be used include "HM8006" manufactured by JSR Corporation. The heating and exposure conditions can be appropriately determined depending on the type of organic underlayer film-forming composition used, etc.

[0089] An example of a case where an organic underlayer film is formed indirectly on a substrate is a case where an organic underlayer film is formed on a low dielectric insulating film formed on a substrate.

[0090] [Resist underlayer film forming step] In this step, a resist underlayer film is formed by directly or indirectly applying a composition for forming a resist underlayer film to a substrate. In this step, a coating film of the composition for forming a resist underlayer film is formed directly or indirectly on the substrate, and this coating film is usually heated to be cured or the like to form the resist underlayer film.

[0091] In this step, the above-described composition for forming a resist underlayer film is used as the composition for forming a resist underlayer film.

[0092] Examples of the substrate include insulating films such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane, and resin substrates. The substrate may also be a substrate patterned with wiring grooves (trenches), plug grooves (vias), and the like.

[0093] The method for applying the composition for forming a resist underlayer film is not particularly limited, and examples thereof include a rotary coating method.

[0094] Examples of the case where the composition for forming a resist underlayer film is indirectly applied to a substrate include the case where the composition for forming a resist underlayer film is applied onto another film formed on the substrate, etc. Examples of the other film formed on the substrate include an organic underlayer film formed by the organic underlayer film forming step described above, an anti-reflective film, a low-dielectric insulating film, etc.

[0095] When the coating film is heated, the atmosphere is not particularly limited, and examples thereof include air and nitrogen atmospheres. Typically, the coating film is heated in air. When the coating film is heated, the heating temperature, heating time, and other conditions can be appropriately determined. The lower limit of the heating temperature is preferably 90°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the heating temperature is preferably 550°C, more preferably 450°C, and even more preferably 300°C. The lower limit of the heating time is preferably 15 seconds, and more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, and more preferably 600 seconds.

[0096] When the composition for forming a resist underlayer film contains an acid generator, and this acid generator is a radiation-sensitive acid generator, the formation of the resist underlayer film can be promoted by combining heating and exposure. Examples of the radiation used for exposure include the same radiation as those exemplified in the exposure step described below.

[0097] The lower limit of the average thickness of the resist underlayer film formed in this step is preferably 1 nm, more preferably 3 nm, and even more preferably 5 nm. The upper limit of the average thickness is preferably 500 nm, more preferably 300 nm, and even more preferably 200 nm. The method for measuring the average thickness of the resist underlayer film is as described in the Examples.

[0098] [Resist Film Forming Step] In this step, a resist film is formed by applying a resist film-forming composition directly or indirectly to the resist underlayer film.

[0099] The method for applying the resist film-forming composition is not particularly limited, and examples thereof include a rotary coating method.

[0100] To explain this step in more detail, for example, a resist composition is applied so that the resist film to be formed has a predetermined thickness, and then the applied resist film is pre-baked (hereinafter also referred to as "PB") to volatilize the solvent in the applied film, thereby forming the resist film.

[0101] The PB temperature and PB time can be appropriately determined depending on the type of the resist film-forming composition used, etc. The lower limit of the PB temperature is preferably 30°C, more preferably 50°C. The upper limit of the PB temperature is preferably 200°C, more preferably 150°C. The lower limit of the PB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PB time is preferably 600 seconds, more preferably 300 seconds.

[0102] Examples of the resist composition include positive or negative chemically amplified resist compositions that contain a radiation-sensitive acid generator, positive resist compositions that contain an alkali-soluble resin and a quinone diazide-based photosensitizer, negative resist compositions that contain an alkali-soluble resin and a crosslinking agent, and metal-containing resist compositions that contain a metal such as tin, zirconium, or hafnium.

[0103] [Exposure Step] In this step, the resist film formed in the resist film-forming composition application step is exposed to radiation. This step generates a difference in solubility in an alkaline solution, which is a developer, between the exposed and unexposed areas of the resist film. More specifically, the solubility of the exposed areas of the resist film in an alkaline solution is increased.

[0104] The radiation used for exposure can be appropriately selected depending on the type of the resist film-forming composition used, etc. Examples include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, and particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, and KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ２ Excimer laser light (wavelength 157 nm), Kr ２ Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., also referred to as "EUV") is more preferred, and ArF excimer laser light or EUV is even more preferred. The exposure conditions can be appropriately determined depending on the type of resist film-forming composition used, etc.

[0105] Furthermore, in this process, after the exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined depending on the type of resist film-forming composition used, etc. The lower limit of the PEB temperature is preferably 50°C, more preferably 70°C. The upper limit of the PEB temperature is preferably 200°C, more preferably 150°C. The lower limit of the PEB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PEB time is preferably 600 seconds, more preferably 300 seconds.

[0106] [Development Step] In this step, the exposed resist film is developed. The development of the exposed resist film is preferably alkaline development. The exposure step causes a difference in solubility in an alkaline solution, which is a developer, between the exposed and unexposed portions of the resist film. Therefore, alkaline development removes the exposed portions, which have a relatively high solubility in an alkaline solution, thereby forming a resist pattern.

[0107] The developer used in alkaline development is not particularly limited, and known developers can be used. Examples of developers for alkaline development include alkaline aqueous solutions containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0108] In addition, examples of the developer when organic solvent development is performed include the same solvents as those exemplified as the solvents in the composition for forming a resist underlayer film described above.

[0109] In this step, washing and / or drying may be carried out after the development.

[0110] [Resist Underlayer Film Pattern Forming Step] In this step, the resist underlayer film is etched using the resist pattern as a mask to form a resist underlayer film pattern.

[0111] The etching may be either dry etching or wet etching, but dry etching is preferred.

[0112] Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the elemental composition of the resist underlayer film to be etched, and for example, CHF ３ , C.F. ４ , C ２ F ６ , C ３ F ８ , SF ６ Fluorine-based gases such as Cl ２ , BCl ３ Chlorine gases such as O２ , O ３ , H ２ Oxygen-based gases such as O, H ２ , N.H. ３ , CO, CO ２ , C.H. ４ , C ２ H ２ , C ２ H ４ , C ２ H ６ , C ３ H ４ , C ３ H ６ , C ３ H ８ , reducing gases such as HF, HI, HBr, HCl, and NO, He, N ２ Inert gases such as Ar and the like are used. These gases can also be used in combination. For dry etching of the resist underlayer film, a fluorine-based gas is usually used, and a mixture of this with an oxygen-based gas and an inert gas is preferably used.

[0113] [Etching Step] In this step, etching is performed using the resist underlayer film pattern as a mask. More specifically, etching is performed one or more times using the pattern formed on the resist underlayer film obtained in the resist underlayer film pattern forming step as a mask to obtain a patterned substrate.

[0114] When an organic underlayer film is formed on a substrate, a pattern of the organic underlayer film is formed by etching the organic underlayer film using the resist underlayer film pattern as a mask, and then a pattern is formed on the substrate by etching the substrate using this organic underlayer film pattern as a mask.

[0115] The etching may be either dry etching or wet etching, but dry etching is preferred.

[0116] Dry etching for forming a pattern on the organic underlayer film can be performed using a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the elemental composition of the resist underlayer film and the organic underlayer film to be etched. The etching gas can be suitably selected from the gases used for etching the resist underlayer film described above, and these gases can also be used in combination. An oxygen-based gas is usually used for dry etching the organic underlayer film using the resist underlayer film pattern as a mask.

[0117] Dry etching when forming a pattern on a substrate using an organic underlayer film pattern as a mask can be performed using a known dry etching apparatus. The etching gas used in dry etching can be appropriately selected depending on the elemental composition of the organic underlayer film and the substrate to be etched, and examples thereof include the same etching gases as those exemplified as the etching gases used in dry etching of the organic underlayer film. Etching may be performed multiple times using different etching gases. Note that if the resist underlayer film remains on the substrate or on the resist underlayer pattern after the substrate pattern formation step, the resist underlayer film can be removed by performing the removal step described below.

[0118] [Removal Step] In this step, the resist underlayer film pattern is removed with a basic liquid. This step removes the resist underlayer film from the substrate. Furthermore, residual resist underlayer film remaining after etching can be removed.

[0119] The basic liquid is not particularly limited as long as it is a basic solution containing a basic compound. Examples of basic compounds include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH"), tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo[5.4.0]-7-undecene, and 1,5-diazabicyclo[4.3.0]-5-nonene. Among these, ammonia is preferred from the viewpoint of avoiding damage to the substrate.

[0120] From the viewpoint of further improving the removability of the resist underlayer film, the basic liquid is preferably a liquid containing a basic compound and water, or a liquid containing a basic compound, hydrogen peroxide, and water.

[0121] The method for removing the resist underlayer film is not particularly limited as long as it is a method that can bring the resist underlayer film into contact with a basic liquid, and examples thereof include a method of immersing a substrate in a basic liquid, a method of spraying a basic liquid, and a method of applying a basic liquid.

[0122] The conditions for removing the resist underlayer film, such as temperature and time, are not particularly limited and can be appropriately determined depending on the film thickness of the resist underlayer film, the type of basic solution used, etc. The lower limit of the temperature is preferably 20°C, more preferably 40°C, and still more preferably 50°C. The upper limit of the temperature is preferably 300°C, more preferably 100°C. The lower limit of the time is preferably 5 seconds, more preferably 30 seconds. The upper limit of the time is preferably 10 minutes, more preferably 180 seconds.

[0123] In this step, after removing the resist underlayer film, washing and / or drying may be carried out.

[0124] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0125] [Measurement of Weight-Average Molecular Weight (Mw)] The weight-average molecular weight (Mw) of the polysiloxane was measured by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions: (Measurement Conditions) Eluent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection amount: 100 μL Column temperature: 40°C Detector: differential refractometer Standard material: monodisperse polystyrene

[0126] [Concentration of Polysiloxane in Solution] 0.5 g of the polysiloxane solution was baked at 250°C for 30 minutes, and the mass of the residue obtained was measured. The mass of this residue was divided by the mass of the polysiloxane solution to calculate the concentration of the polysiloxane solution (unit: mass%).

[0127] [Average Thickness of Resist Underlayer Film] The average thickness of the resist underlayer film was measured using a spectroscopic ellipsometer ("M2000D" manufactured by J.A. WOOLLAM Co., Ltd.) Specifically, the film thickness was measured at nine arbitrary positions at 5 cm intervals including the center of the resist underlayer film, and the average value of the film thicknesses was calculated to obtain the average thickness.

[0128] <Synthesis of Polysiloxane> The monomers (M-1) to (M-8), (Q-1), (P-1) to (P-4), and (N-1) to (N-4) used in the synthesis in Synthesis Examples 1-1 to 1-12 and Comparative Synthesis Examples 1-1 to 1-2 are shown below. In the following Synthesis Examples 1-1 to 1-12 and Comparative Synthesis Examples 1-1 to 1-2, mol % refers to the value for each monomer when the total number of moles of the monomers used is taken as 100 mol %.

[0129]

[0130]

[0131]

[0132] Synthesis Example 1: Synthesis of Polysiloxane (A-1) In a reaction vessel, the above compounds (M-1) and (Q-1) were dissolved in 62 parts by mass of propylene glycol monoethyl ether to a molar ratio of 30 / 70 (mol %) to prepare a monomer solution. The temperature inside the reaction vessel was heated to 60°C, and 40 parts by mass of a 9.1% by mass aqueous oxalic acid solution was added dropwise over 20 minutes while stirring. The reaction started when the dropwise addition began, and was carried out for 4 hours. After completion of the reaction, the reaction vessel was cooled to below 30°C. 550 parts by mass of propylene glycol monoethyl ether was added to the cooled reaction solution, and water, alcohols produced by the reaction, and excess propylene glycol monoethyl ether were removed using an evaporator to obtain a propylene glycol monoethyl ether solution of polysiloxane (A-1). The Mw of polysiloxane (A-1) was 1,900. The concentration of polysiloxane (A-1) in the propylene glycol monoethyl ether solution was 20.0% by mass.

[0133] [Synthesis Examples 1-2 to 1-12 and Comparative Synthesis Examples 1-1 to 1-2] Synthesis of polysiloxanes (A-2) to (A-12) and (AJ-1) to (AJ-2) Propylene glycol monoethyl ether solutions of polysiloxanes (A-2) to (A-12) and (AJ-1) to (AJ-2) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of each monomer shown in Table 1 below were used. A "-" next to a monomer in Table 1 below indicates that the corresponding monomer was not used. The Mw of the obtained polysiloxanes and their concentrations (mass%) in the solutions are also shown in Table 1 below.

[0134]

[0135] <Preparation of Composition for Forming Resist Underlayer Film> The solvents, basic compounds, and photoacid generators used in preparing compositions for forming resist underlayer films (hereinafter also simply referred to as "compositions") are shown below. In the following Examples 2-1 to 2-14 and Comparative Examples 2-1 and 2-2, unless otherwise specified, parts by mass indicate values ​​when the total mass of the components used is 100 parts by mass.

[0136] [B] Solvent B-1: Propylene glycol monoethyl ether B-2: Propylene glycol monomethyl ether acetate

[0137] [C] Basic compound C-1: a compound represented by the following formula (C-1):

[0138]

[0139] [D] Photoacid generator D-1: a compound represented by the following formula (D-1):

[0140]

[0141] Example 1 Preparation of Resist Underlayer Film-Forming Composition (J-1) 0.3 parts by mass of (A-1) as polysiloxane, 85.23 parts by mass of (B-1) as solvent (including the solvent contained in the polysiloxane solution), 9.47 parts by mass of (B-2), and 5.00 parts by mass of water were mixed, and the resulting solution was filtered through a polytetrafluoroethylene filter having a pore size of 0.2 μm to prepare a resist underlayer film-forming composition (J-1).

[0142] Examples 2-2 to 2-14 and Comparative Examples 2-1 to 2-2 Preparation of compositions (J-2) to (J-14) and (j-1) to (j-2) for forming resist underlayer films Compositions (J-2) to (J-14) for forming resist underlayer films of Examples 2 to 19 and compositions (j-1) to (j-2) for forming resist underlayer films of Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that the types and blending amounts of each component shown in Table 2 below were used.

[0143]

[0144] <Evaluation> Using the resist underlayer film-forming composition prepared above, the ability to inhibit pattern collapse was evaluated by the following method. The evaluation results are shown in Table 3 below.

[0145] <Preparation of Resist Composition for EUV Exposure> Resist composition for EUV exposure (R-1) was obtained by mixing 100 parts by mass of a polymer having a structural unit (1) derived from 4-hydroxystyrene, a structural unit (2) derived from styrene, and a structural unit (3) derived from 4-t-butoxystyrene (the proportions of the structural units were (1) / (2) / (3)=65 / 5 / 30 (mol %)), 1.0 part by mass of triphenylsulfonium trifluoromethanesulfonate as a radiation-sensitive acid generator, and 4,400 parts by mass of ethyl lactate and 1,900 parts by mass of propylene glycol monomethyl ether acetate as a solvent, and filtering the resulting solution through a filter with a pore size of 0.2 μm.

[0146] [Resistance to Collapse of Resist Pattern] An organic underlayer film forming material ("HM8006" manufactured by JSR Corporation) was applied onto a 12-inch silicon wafer by a spin coating method using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. The composition prepared above was applied onto this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a silicon-containing film with an average thickness of 20 nm. A resist composition (R-1) for EUV exposure was applied onto the silicon-containing film formed above, heated at 130°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 50 nm. Next, using an EUV scanner ("TWINSCAN" manufactured by ASML), Using a mask (NXE:3300B) (NA 0.3, sigma 0.9, quadrupole illumination), the resist film was irradiated with extreme ultraviolet light while the line width of the mask on the wafer was changed stepwise. 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. Thereafter, the substrate was developed by the puddle method using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (20°C to 25°C), followed by washing with water and drying to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Performance Imaging Co., Ltd.) was used to measure and observe the resist pattern of the evaluation substrate. The resist pattern collapse suppression was evaluated as "A" (good) when collapse of the 1:1 line and space pattern with a line width of 15 nm on the evaluation substrate was not confirmed, as "B" (fairly good) when collapse of the 1:1 line and space pattern with a line width of 15 nm on the evaluation substrate was confirmed but collapse of the 1:1 line and space pattern with a line width of 20 nm on the evaluation substrate was not confirmed, and as "C" (poor) when collapse of the 1:1 line and space pattern with a line width of 20 nm on the evaluation substrate was confirmed.

[0147]

[0148] <Evaluation> Using the resist underlayer film-forming compositions prepared above, the ability to inhibit pattern collapse was evaluated by the following method. The evaluation results are shown in Table 4 below.

[0149] <Preparation of Resist Composition (T-1)>

[0150] [Synthesis of Metal-Containing Compound] Compound (S-1), which was a metal-containing compound used in preparing resist composition (T-1), was synthesized by the following procedure. In a reaction vessel, 6.5 parts by mass of isopropyltin trichloride was added to 150 mL of 0.5 N aqueous sodium hydroxide solution while stirring, and the mixture was stirred for 2 hours. The precipitate was collected by filtration, washed twice with 50 parts by mass of water, and then dried to obtain compound (S-1). Compound (S-1) was a hydroxide oxide product (i-PrSnO) of the hydrolysis product of isopropyltin trichloride. （３／２-ｘ／２） (OH) ｘ (where 0<x<3 is the structural unit).

[0151] 2 parts by mass of the compound (S-1) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the resulting mixture was passed through an activated 4 Å molecular sieve to remove residual water, followed by filtration through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.2 μm to prepare resist composition (T-1).

[0152] [Resistance to Collapse of Resist Pattern] An organic underlayer film-forming material ("HM8006" manufactured by JSR Corporation) was applied onto a 12-inch silicon wafer by spin coating using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), and then heated at 250°C for 60 seconds to form an organic underlayer film with an average thickness of 100 nm. The resist underlayer film-forming composition prepared above was applied onto this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film with an average thickness of 5 nm. Resist composition (T-1) was applied onto this resist underlayer film by spin coating using the spin coater, and after a predetermined time had elapsed, the resist film was heated at 90°C for 60 seconds and then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 35 nm. An EUV scanner ("TWINSCAN" manufactured by ASML) was used. Using a NXE:3300B (NA 0.3, sigma 0.9, quadrupole illumination), the resist film was exposed while the line width of the mask on the wafer was changed stepwise. After exposure, the substrate was heated at 110°C for 60 seconds, and then cooled at 23°C for 60 seconds. Thereafter, 2-heptanone (20-25°C) was used as the developer, and the substrate was developed by the puddle method, followed by drying, to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Tech Corporation's "SU8220") was used to measure and observe the resist pattern of the evaluation substrate. The resist pattern collapse suppression was evaluated as "A" (good) when collapse of the 1:1 line and space pattern with a line width of 15 nm on the evaluation substrate was not confirmed, as "B" (fairly good) when collapse of the 1:1 line and space pattern with a line width of 15 nm on the evaluation substrate was confirmed but collapse of the 1:1 line and space pattern with a line width of 20 nm on the evaluation substrate was not confirmed, and as "C" (poor) when collapse of the 1:1 line and space pattern with a line width of 20 nm on the evaluation substrate was confirmed.

[0153]

[0154] As is clear from the results in Tables 3 and 4 above, the resist underlayer films formed from the compositions for forming a resist underlayer film of the Examples were superior in the ability to suppress pattern collapse compared to the resist underlayer films formed from the compositions for forming a resist underlayer film of the Comparative Examples.

[0155] According to the composition for forming a resist underlayer film and the method for producing a semiconductor substrate of the present invention, a resist underlayer film having excellent pattern collapse suppression properties can be formed, and therefore, they can be suitably used in the production of semiconductor substrates, etc.

Claims

1. A composition for forming a resist underlayer film, comprising: a polysiloxane having a first structural unit represented by the following formula (1); and a solvent: (In the above formula (1), X is a monovalent group represented by the following formula (1-1). a is an integer of 1 to 3. When a is 2 or more, multiple Xs may be the same or different. R １ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. b is an integer of 0 to 2. When b is 2, two R １ are the same or different, provided that a + b is 3 or less.) (In the above formula (1-1), L １ is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. * is a bond to the silicon atom in the above formula (1). (i) R ２ and R ３ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, or (ii) R ２ is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and R ３ and R ４ represent a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which is bonded to each other together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom, or (iii) R ２ ~R ４ represent a trivalent alicyclic hydrocarbon group having 5 to 20 carbon atoms which is bonded to each other and constituted together with the carbon atoms to which they are bonded, or a group in which the alicyclic hydrocarbon group is substituted with a halogen atom.

2. In the above formula (1-1), R ２ ~R ４ 2. The composition for forming a resist underlayer film according to claim 1, wherein is a monovalent hydrocarbon group having 1 to 10 carbon atoms.

3. In the above formula (1-1), R ２ ~R ４ 2. The composition for forming a resist underlayer film according to claim 1, wherein is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.

4. In the above formula (1-1), L １ The composition for forming a resist underlayer film according to claim 1 , wherein is a single bond.

5. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the content of the first structural unit in all structural units constituting the polysiloxane is 0.5 mol % or more and 70 mol % or less.

6. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the polysiloxane has a second structural unit represented by the following formula (2): (In the above formula (2), Y is a substituted or unsubstituted monovalent alkoxy group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. c is an integer of 0 to 3. When c is 2 or more, multiple Ys are the same or different.) 7. The composition for forming a resist underlayer film according to claim 6, wherein the content of the second structural unit in all structural units constituting the polysiloxane is 20 mol % or more and 95 mol % or less.

8. The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the first polysiloxane has a third structural unit represented by the following formula (3): (In the above formula (3), Z is a monovalent heteroatom-containing group having 1 to 20 carbon atoms and containing at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom. d is an integer of 1 to 3. When d is 2 or more, multiple Zs may be the same or different. R ４ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, or a halogen atom. e is an integer of 0 to 2. When e is 2, two R １ are the same or different, provided that d+e is 3 or less.

9. The composition for forming a resist underlayer film according to claim 8, wherein the content of the third structural unit in all structural units constituting the polysiloxane is 1 mol % or more and 30 mol % or less.

10. A method for manufacturing a semiconductor substrate, comprising: a step of forming a resist underlayer film by directly or indirectly applying the composition for forming a resist underlayer film according to any one of claims 1 to 4 to a substrate; a step of forming a resist film by directly or indirectly applying the composition for forming a resist film to the resist underlayer film; a step of exposing the resist film to radiation; and a step of developing the exposed resist film to form a resist pattern.

Images