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

Abstract

Provided is a composition or the like that is used for forming an underlayer film of a metal-containing resist in electron beam or extreme ultraviolet ray lithography, that suppresses collapse of a metal-containing resist pattern, and that can form a resist underlayer film from which a fine metal-containing resist pattern can be formed. The resist underlayer film forming composition according to the present invention is used for forming an underlayer film of a metal-containing resist film in electron beam or extreme ultraviolet ray lithography, and contains a solvent and a polysiloxane compound having a first structural unit represented by formula (1).

Description

[Technical Field]

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

[0002] A multilayer resist process is sometimes used for pattern formation in the manufacture of semiconductor substrates. In the multilayer resist process, for example, a resist film laminated on a substrate via a resist underlayer film such as an organic underlayer film or a silicon-containing film is exposed and developed to obtain a resist pattern, which is then used as a mask to perform etching to form a patterned substrate (see International Publication No. 2012 / 039337).

[0003] Recently, as semiconductor devices have become increasingly highly integrated, there has been a trend toward shorter wavelength exposure light, from KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) to extreme ultraviolet (13.5 nm, EUV), in order to form finer patterns. Electron beam lithography is also sometimes used to form finer patterns. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2012 / 039337 Summary of the Invention [Problem to be solved by the invention]

[0005] In a multilayer resist process, it is necessary to be able to form a fine metal-containing resist pattern using a composition for forming a metal-containing resist film on a silicon-containing film, which is a resist underlayer film (hereinafter also referred to as a "metal-containing resist film-forming composition"). However, in conventional electron beam or extreme ultraviolet lithography, it is difficult to prevent the collapse of the metal-containing resist pattern and form a fine metal-containing resist pattern with a good shape. In particular, the finer the resist pattern formed, the more likely the collapse of the metal-containing resist pattern occurs during development, etc.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a composition for forming a resist underlayer film, which is used to form an underlayer film of a metal-containing resist in electron beam or extreme ultraviolet lithography, and which is capable of forming a resist underlayer film that can suppress collapse of the metal-containing resist pattern and form a fine metal-containing resist pattern, and a method for manufacturing a semiconductor substrate using such a composition for forming a resist underlayer film. [Means for solving the problem]

[0007] The invention made to solve the above-mentioned problems is a composition for forming a resist underlayer film used to form an underlayer film of a metal-containing resist in electron beam or extreme ultraviolet lithography, the composition for forming a resist underlayer film containing a polysiloxane compound having a first structural unit represented by the following formula (1) (hereinafter also referred to as "compound [A]") and a solvent (hereinafter also referred to as "solvent [B]"). [ka] In formula (1), X is an organic group having at least one structure selected from a hydroxy group, a carbonyl group, and an ether bond. 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. 1is a group other than X. 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.

[0008] Another invention made to solve the above-mentioned problems is a method for producing a semiconductor substrate, comprising the steps of: applying a composition for forming a resist underlayer film directly or indirectly to a substrate; applying a composition for forming a metal-containing resist film to the resist underlayer film formed in the above-mentioned step of applying the composition for forming a resist underlayer film; exposing the metal-containing resist film formed in the above-mentioned step of applying the composition for forming a metal-containing resist film to an electron beam or extreme ultraviolet light; and developing the exposed metal-containing resist film, wherein the composition for forming a resist underlayer film is the above-mentioned composition for forming a resist underlayer film. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a composition for forming a resist underlayer film, which is used for forming an underlayer film of a metal-containing resist in electron beam or extreme ultraviolet lithography, and which is capable of forming a resist underlayer film that suppresses collapse of the metal-containing resist pattern and enables the formation of a fine metal-containing resist pattern, and a method for manufacturing a semiconductor substrate using such a composition for forming a resist underlayer film. DETAILED DESCRIPTION OF THE INVENTION

[0010] The composition for forming a resist underlayer film and the method for producing a semiconductor substrate of the present invention will be described in detail below.

[0011] <Composition for forming resist underlayer film> The composition for forming a resist underlayer film contains a compound [A] and a solvent [B]. The composition for forming a resist underlayer film may contain an additive other than the compound [A] and the solvent [B] (hereinafter, also referred to as "additive [C]"), as long as the effect of the present invention is not impaired.

[0012] The composition for forming a resist underlayer film contains the compound [A] and the solvent [B], and therefore, in electron beam or extreme ultraviolet lithography, a fine metal-containing resist pattern can be formed on the metal-containing resist underlayer film, with pattern collapse suppressed.

[0013] The composition for forming a resist underlayer film has the above-mentioned effects and can therefore be suitably used as a composition for forming an underlayer film of a metal-containing resist film in electron beam or extreme ultraviolet lithography.

[0014] Hereinafter, each component contained in the composition for forming a resist underlayer film will be described.

[0015] [[A] compound] The compound [A] is a polysiloxane compound having a first structural unit (hereinafter also referred to as "structural unit (I)") represented by the following formula (1) described below. In this specification, "polysiloxane compound" means a compound containing a siloxane bond (-Si-O-Si-). The compound [A] may have structural units other than the structural unit (I) described above, as long as the effects of the present invention are not impaired. Examples of such other structural units include a second structural unit (hereinafter also referred to as "structural unit (II)") represented by the following formula (2) described below, and a third structural unit (hereinafter also referred to as "structural unit (III)") represented by the following formula (3) described below.

[0016] Each structural unit contained in the compound [A] will be explained below.

[0017] (Structural unit (I)) The structural unit (I) is a structural unit represented by the following formula (1): The compound [A] can have one or more types of structural unit (I).

[0018] [ka]

[0019] In the above formula (1), X is an organic group containing at least one structure selected from the group consisting of a hydroxy group, a carbonyl group, and an ether bond. 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. 1 is a group other than X. 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.

[0020] In this specification, the term "organic group" means a group containing at least one carbon atom, and the term "number of carbon atoms" means the number of carbon atoms constituting the group.

[0021] 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 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 a monovalent heteroatom-containing group (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 group (hereinafter also referred to as "group (γ)"). 1 The monovalent organic group having 1 to 20 carbon atoms represented by the following formula does not include a group represented by X.

[0022] In this specification, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. A "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a linear structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. An "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed only of an alicyclic structure, and may contain a linear structure as part of it. An "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and may contain a linear structure or an alicyclic structure as part of it.

[0023] 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, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0024] 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, iso-butyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0025] 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.

[0026] 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.

[0027] Examples of heteroatoms constituting the divalent or monovalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0028] Examples of the divalent heteroatom-containing group include -O-, -C(=O)-, -S-, -C(=S)-, -NR'-, and groups formed by combining two or more of these, where R' is a hydrogen atom or a monovalent hydrocarbon group.

[0029] Examples of the monovalent heteroatom-containing group include a halogen atom, a hydroxy group, a carboxy group, a cyano group, an amino group, and a sulfanyl group.

[0030] 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.

[0031] R 1 is preferably a monovalent organic group having 1 to 20 carbon atoms, more preferably a monovalent chain hydrocarbon group, a monovalent aromatic hydrocarbon group, or a monovalent group in which some or all of the hydrogen atoms of a monovalent hydrocarbon group have been substituted with a monovalent heteroatom-containing group, more preferably an alkyl group or an aryl group, and even more preferably a methyl group, an ethyl group, or a phenyl group.

[0032] b is preferably 0 or 1, and more preferably 0.

[0033] X in the above formula (1) is an organic group having at least one structure selected from the group consisting of a hydroxy group, a carbonyl group, and an ether bond.

[0034] Examples of the organic group having a hydroxy group include hydroxyalkyl groups such as a hydroxymethyl group and a hydroxyethyl group.

[0035] Examples of organic groups having a carbonyl group include organic groups having an ester bond, organic groups having a carbonate structure, organic groups having an amide bond, organic groups having an acyl group, and organic groups having a carboxylic anhydride group.

[0036] Examples of the organic group having a carbonyl group include groups represented by the following formula (1-1) and the following formula (1-2).

[0037] [ka]

[0038] In the above formula (1-1) and formula (1-2), R 2 and R 4 is a monovalent organic group having 1 to 20 carbon atoms. n is 1 or 2. When n is 2, multiple R 2 are the same or different. R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. L is a single bond or a divalent linking group. * indicates the bonding site with the silicon atom in the above formula (1).

[0039] R 2 and R 4 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R 1 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula include the same groups as those exemplified above.

[0040] R 2 and R 4 is preferably a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably a monovalent chain hydrocarbon group having 1 to 20 carbon atoms.

[0041] Examples of the divalent linking group represented by L include divalent organic groups having 1 to 20 carbon atoms. Examples of the divalent organic group having 1 to 20 carbon atoms include the above-mentioned R 1 Examples of the monovalent organic group include groups in which one hydrogen atom has been removed from the monovalent organic groups exemplified as the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula:

[0042] L is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent chain hydrocarbon group having 1 to 20 carbon atoms, and even more preferably an alkanediyl group having 1 to 20 carbon atoms. The number of carbon atoms in the group represented by L is preferably 1 to 12, more preferably 1 to 6. A more preferred form of the group represented by L is -(CH2) m - (where m is an integer of 1 to 6).

[0043] Examples of the organic group having an ether bond for X in formula (1) include a t-butoxymethyl group, a t-butoxyethyl group, and an organic group having an acetal structure.

[0044] a is preferably 1 or 2, and more preferably 1.

[0045] Examples of the structural unit (I) include structural units derived from compounds represented by the following formulas (1-1) to (1-10).

[0046] [ka]

[0047] The lower limit of the content of the structural unit (I) in the compound [A] is preferably 0.1 mol%, more preferably 1 mol%, even more preferably 2 mol%, and even more preferably 3 mol%, based on the total structural units constituting the compound [A]. The upper limit of the content of the structural unit (I) is preferably 80 mol%, more preferably 50 mol%, and even more preferably 20 mol%. By ensuring that the content of the structural unit (I) is within the above range, a fine resist pattern that has excellent cross-sectional rectangularity and is resistant to collapse can be formed when a resist pattern is formed on the resist underlayer film by electron beam or extreme ultraviolet lithography.

[0048] (Structural unit (II)) The structural unit (II) is a structural unit represented by the following formula (2): When the compound [A] has the structural unit (II), the oxygen gas etching resistance of the resist underlayer film formed from the composition for forming a resist underlayer film can be improved. The compound [A] can have one or more types of the structural unit (II).

[0049] [ka]

[0050] In the above formula (2), R 5 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 R 5 are the same or different.

[0051] R 5 Examples of the substituted or unsubstituted monovalent alkoxy group having 1 to 20 carbon atoms represented by the formula (I) include a methoxy group, an ethoxy group, and a propoxy group.

[0052] R 5 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0053] R5 As the alkoxy group, a substituted or unsubstituted monovalent alkoxy group having 1 to 20 carbon atoms is preferred, and a methoxy group or an ethoxy group is more preferred.

[0054] c is preferably 1 or 2.

[0055] When the compound [A] has the structural unit (II) as another structural unit, the lower limit of the content of the structural unit (II) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%, 60 mol%, or 70 mol%, based on the total structural units constituting the compound [A]. The upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%.

[0056] (Structural unit (III)) The structural unit (III) is a structural unit represented by the following formula (3): When the compound [A] has the structural unit (III), the storage stability and coatability of the composition for forming a resist underlayer film can be improved. The compound [A] can have one or more types of the structural unit (III).

[0057] [ka]

[0058] In the above formula (3), R 6 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. d is an integer of 1 to 3. When d is 2, R 6 are the same or different. R 7 is a substituted or unsubstituted 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 there are multiple e's, multiple R 3 are the same or different, provided that d+e is 3 or less.

[0059] R 6 Examples of the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R 1Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula:

[0060] d is preferably 1.

[0061] R 7 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0062] R 7 As the alkoxy group, a substituted or unsubstituted monovalent alkoxy group having 1 to 20 carbon atoms is preferred, and a methoxy group or an ethoxy group is more preferred.

[0063] As e, 0 or 1 is preferred.

[0064] When the compound [A] has the structural unit (III) as another structural unit, the lower limit of the content of the structural unit (III) is preferably 0.1 mol%, more preferably 1 mol%, and even more preferably 2 mol%, 3 mol%, or 5 mol%, based on the total structural units constituting the compound [A]. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%.

[0065] The lower limit of the total content of the structural units (I), (II), and (III) relative to all structural units constituting the compound [A] is preferably 80 mol%, more preferably 90 mol%, and in some cases even more preferably 95 mol% or 99 mol%. The upper limit of the total content may be 100 mol%.

[0066] The lower limit of the content of the compound [A] in the composition for forming a resist underlayer film is preferably 0.1 mass %, more preferably 0.3 mass %, and even more preferably 0.5 mass %, based on all components contained in the composition for forming a resist underlayer film, and the upper limit of the content is preferably 10 mass %, more preferably 5 mass %, even more preferably 3 mass %, and even more preferably 2 mass %.

[0067] The compound [A] 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 compound [A] is in the form of a polymer, the lower limit of the weight average molecular weight (Mw) of the compound [A] in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 1,000, more preferably 1,200, and even more preferably 1,500. The upper limit of the Mw is preferably 10,000, more preferably 5,000, and even more preferably 3,000.

[0068] In this specification, the Mw of compound [A] is a value measured by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions: Eluent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: differential refractometer Standard material: monodisperse polystyrene

[0069] The [A] compound can be synthesized by conventional methods using monomers that provide each structural unit. For example, it can be synthesized by hydrolysis and condensation of a monomer that provides structural unit (I) and, if necessary, monomers that provide other structural units in a solvent in the presence of a catalyst such as oxalic acid and water. It is believed that each monomer is incorporated into the [A] compound regardless of its type through the hydrolysis and condensation reaction. Therefore, the content ratio of structural unit (I) and other structural units in the synthesized [A] compound is usually equivalent to the ratio of the amounts of each monomer used in the synthesis reaction.

[0070] [[B] Solvent] The solvent [B] is not particularly limited, and examples thereof include alcohol solvents, ketone solvents, ether solvents, ester solvents, and nitrogen-containing solvents. The solvent [B] is usually an organic solvent. The composition for forming a resist underlayer film may contain one or more solvents [B].

[0071] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, and iso-butanol, and polyhydric alcohol solvents such as ethylene glycol, 1,2-propylene glycol, diethylene glycol, and dipropylene glycol.

[0072] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-butyl ketone, cyclohexanone, and 2-heptanone.

[0073] 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.

[0074] 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.

[0075] Examples of nitrogen-containing solvents include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

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

[0077] Examples of ether solvents having a glycol structure and ester 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 or propylene glycol monoethyl ether is preferred.

[0078] The lower limit of the content of the solvent [B] in the composition for forming a resist underlayer film is preferably 90 mass %, more preferably 92.5 mass %, and even more preferably 95 mass %, based on all components contained in the composition for forming a resist underlayer film.The upper limit of the content is preferably 99.9 mass %, more preferably 99.5 mass %, and even more preferably 99 mass %.

[0079] [[C] Additives] Examples of the additive [C] include an acid generator, a basic compound (including a base generator), a radical generator, a surfactant, colloidal silica, colloidal alumina, an organic polymer, water, etc. The composition for forming a resist underlayer film can contain one or more types of the additive [C].

[0080] When the composition for forming a resist underlayer film contains the additive [C], the content of the additive [C] in the composition for forming a resist underlayer film can be appropriately determined depending on the type of the additive [C] 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 a resist underlayer film is not particularly limited, and the composition can be prepared according to a conventional method, for example, by mixing a solution of the compound [A], a solvent [B], and, if necessary, an additive [C] 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 of manufacturing semiconductor substrate> The method for producing a semiconductor substrate includes the steps of: applying a resist underlayer film-forming composition directly or indirectly to a substrate (hereinafter also referred to as a "resist underlayer film-forming composition applying step"); applying a metal-containing resist film-forming composition directly or indirectly to the resist underlayer film formed by the resist underlayer film-forming composition applying step (hereinafter also referred to as a "metal-containing resist film-forming composition applying step"); exposing the metal-containing resist film formed by the metal-containing resist film-forming composition applying step to an electron beam or extreme ultraviolet light (hereinafter also referred to as an "exposure step"); and developing the exposed metal-containing resist film (hereinafter also referred to as a "development step"). In the method for producing a semiconductor substrate, the resist underlayer film-forming composition described above is used as the resist underlayer film-forming composition.

[0083] The method for manufacturing a semiconductor substrate may further include, as necessary, a step of heating the coating film formed in the coating step of the composition for forming a resist underlayer film (hereinafter also referred to as a "heating step") after the coating step of the composition for forming a resist underlayer film and before the coating step of the composition for forming a metal-containing resist film.

[0084] The method for producing a semiconductor substrate may further include, as necessary, a step of forming an organic underlayer film directly or indirectly on the substrate (hereinafter also referred to as an "organic underlayer film forming step") before the step of applying the composition for forming a resist underlayer film.

[0085] The method for manufacturing a semiconductor substrate may further include a step of performing etching using the formed resist pattern or the like as a mask after the developing step (hereinafter also referred to as an "etching step"). By this etching step, a fine pattern is formed on the substrate itself.

[0086] According to this method for producing a semiconductor substrate, the resist underlayer film is formed using the above-mentioned composition for forming a resist underlayer film, and exposure is performed with electron beams or extreme ultraviolet rays, so that a fine resist pattern can be formed on the metal-containing resist underlayer film. Therefore, according to this method for producing a semiconductor substrate, a semiconductor substrate on which a fine pattern is formed can be efficiently produced. Note that the "semiconductor substrate" in this production method refers to a substrate used in a semiconductor device (semiconductor element), and is not limited to a substrate made of a semiconductor material.

[0087] The size of the resist pattern and substrate pattern (pattern formed on the substrate) formed in this manufacturing method preferably has portions with line widths of 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, or 15 nm or less. The minimum line width of the formed resist pattern may be, for example, 2 nm, 5 nm, or 10 nm.

[0088] Each step of the method for manufacturing a semiconductor substrate will be described below.

[0089] [Organic lower layer film formation process] In this step, an organic underlayer film is formed directly or indirectly on a substrate, which will be described later, before the resist underlayer film-forming composition coating step, which will be described later. This step is an optional step. By this step, an organic underlayer film is formed directly or indirectly on a substrate. Note that "before the resist underlayer film-forming composition coating step" does not mean only immediately before the resist underlayer film-forming composition coating step, but also means a point upstream of the resist underlayer film-forming composition coating step. Therefore, other optional steps may be included between this step and the resist underlayer film-forming composition coating step.

[0090] The organic underlayer film can be formed, for example, by coating an organic underlayer film-forming composition. 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 coated onto a substrate, and the resulting coating film is then 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. Heating and exposure conditions can be appropriately determined depending on the type of organic underlayer film-forming composition used.

[0091] 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.

[0092] [Resist underlayer film forming composition application process] In this step, the composition for forming a resist underlayer film is applied directly or indirectly to a substrate. By this step, a coating film of the composition for forming a resist underlayer film is formed directly or indirectly on the substrate. In this step, the composition for forming a resist underlayer film described above is used as the composition for forming a resist underlayer film.

[0093] 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.

[0094] The method for applying the composition for forming a resist underlayer film is not particularly limited, and examples thereof include a rotary coating method.

[0095] 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.

[0096] [Heating process] In this step, after the step of applying the composition for forming a resist underlayer film, and before the step of applying the composition for forming a metal-containing resist film, the coating film formed in the step of applying the composition for forming a resist underlayer film is heated. This heating causes the coating film to harden, thereby forming a resist underlayer film.

[0097] The atmosphere in which the coating film is heated is not particularly limited, and examples include air and nitrogen atmospheres. Typically, the coating film is heated in air. When heating the coating film, the heating temperature, heating time, and other conditions can be determined appropriately. The lower limit of the heating temperature may be, for example, 150°C, but 200°C is preferred, and 210°C or 220°C is more preferred. By setting the heating temperature to the above lower limit or higher, amino groups can be sufficiently generated. 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, more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, more preferably 600 seconds.

[0098] When the composition for forming a resist underlayer film contains an acid generator as the additive [C], and this acid generator is an acid generator that generates an acid upon exposure, the formation of the resist underlayer film can be promoted by combining heating and exposure. Also, when the acid generator is an acid generator that generates an acid upon heating, the acid is generated by the above-mentioned heating, and the curing reaction can be promoted.

[0099] The lower limit of the average thickness of the resist underlayer film formed by this step is preferably 1 nm, more preferably 3 nm, and even more preferably 5 nm, and the upper limit of the average thickness is preferably 300 nm, more preferably 100 nm, more preferably 50 nm, and even more preferably 20 nm.

[0100] [Metal-containing resist film-forming composition coating process] In this step, a composition for forming a metal-containing resist film is applied directly or indirectly to the resist underlayer film formed in the above step, and a metal-containing resist film is formed directly or indirectly on the resist underlayer film.

[0101] The method for applying the composition for forming a metal-containing resist film is not particularly limited, and examples thereof include a rotary coating method.

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

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

[0104] The composition for forming a metal-containing resist film used in this step includes a composition for forming a metal-containing resist film that contains a compound containing a metal atom (hereinafter also referred to as "metal-containing compound [P]").

[0105] [Metal-containing resist film-forming composition] The composition for forming a metal-containing resist film contains 50% by mass or more of a metal-containing compound [P] in terms of solid content. The composition for forming a metal-containing resist film preferably further contains a solvent [Q], and may further contain other components. Because the composition for forming a metal-containing resist film contains 50% by mass or more of a metal-containing compound [P] in terms of solid content, it can form a resist film with excellent etching resistance.

[0106] ([P]metal-containing compounds) The [P] metal-containing compound is a compound containing a metal atom. The [P] metal-containing compound can be used alone or in combination of two or more. The metal atoms constituting the [P] metal-containing compound can be used alone or in combination of two or more. Here, the term "metal atom" refers to a concept that includes metalloids, i.e., boron, silicon, germanium, arsenic, antimony, and tellurium.

[0107] [P] The metal atom constituting the metal-containing compound is not particularly limited, and examples thereof include metal atoms of Groups 3 to 16. Specific examples of the metal atom include metal atoms of Group 4 such as titanium, zirconium, and hafnium, metal atoms of Group 5 such as tantalum, metal atoms of Group 6 such as chromium and tungsten, metal atoms of Group 8 such as iron and ruthenium, metal atoms of Group 9 such as cobalt, metal atoms of Group 10 such as nickel, metal atoms of Group 11 such as copper, metal atoms of Group 12 such as zinc, cadmium, and mercury, metal atoms of Group 13 such as boron, aluminum, gallium, indium, and thallium, metal atoms of Group 14 such as germanium, tin, and lead, metal atoms of Group 15 such as antimony and bismuth, and metal atoms of Group 16 such as tellurium.

[0108] The metal atoms constituting the [P] metal-containing compound preferably include a first metal atom belonging to Group 4, Group 12, or Group 14 in the periodic table and belonging to Period 4, Period 5, or Period 6. That is, the metal atom preferably includes at least one of titanium, zirconium, hafnium, zinc, cadmium, mercury, germanium, tin, and lead. Thus, the inclusion of the first metal atom in the [P] metal-containing compound further promotes the emission of secondary electrons from the exposed areas of the resist film and the change in the solubility of the [P] metal-containing compound in the developer due to these secondary electrons. As a result, pattern collapse can be more reliably suppressed. The first metal atom is preferably tin or zirconium.

[0109] The metal-containing compound [P] preferably further contains atoms other than the metal atom. Examples of the other atoms include carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms, phosphorus atoms, sulfur atoms, and halogen atoms, among which carbon atoms, hydrogen atoms, and oxygen atoms are preferred. The other atoms in the metal-containing compound [P] may be used singly or in combination of two or more.

[0110] The lower limit of the content of the metal-containing compound [P] in the radiation-sensitive composition for forming a resist film, calculated as solid content, is preferably 70 mass %, more preferably 90 mass %, and even more preferably 95 mass %. The content may be 100 mass %. Here, the solid content in the radiation-sensitive composition for forming a resist film refers to components other than the solvent [Q], which will be described later.

[0111] (Method for synthesizing [P] metal-containing compounds) The metal-containing compound [P] can be obtained by, for example, subjecting a metal compound having a metal atom and a hydrolyzable group, a hydrolyzate of this metal compound, a hydrolysis-condensation product of the metal compound, or a combination thereof to a hydrolysis-condensation reaction, a ligand exchange reaction, or the like. The metal compounds can be used singly or in combination of two or more.

[0112] The metal-containing compound [P] 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 (1)"). By using such metal compound (1), a stable metal-containing compound [P] can be obtained.

[0113] [ka]

[0114] In the above formula (4), M is a metal atom. 1 is a ligand or a monovalent organic group having 1 to 20 carbon atoms. a1 is an integer of 0 to 6. When a1 is 2 or more, multiple L 1 may be the same or different. Y is a monovalent hydrolyzable group. b1 is an integer of 2 to 6. Multiple Ys may be the same or different. 1 is a ligand or organic group that does not fall under Y.

[0115] The metal atom represented by M is preferably a first metal atom, more preferably tin.

[0116] The hydrolyzable group represented by Y can be appropriately changed depending on the metal atom represented by M, and examples thereof include a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, and a substituted or unsubstituted amino group.

[0117] The substituent in the substituted or unsubstituted ethynyl group and substituted or unsubstituted amino group represented by Y is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a chain hydrocarbon group, and even more preferably an alkyl group.

[0118] Examples of the halogen atom represented by Y include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, a chlorine atom is preferred.

[0119] Examples of the alkoxy group represented by Y include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, etc. Among these, an ethoxy group, an i-propoxy group, and an n-butoxy group are preferred.

[0120] Examples of the acyloxy group represented by Y include a formyl group, an acetoxy group, an ethyloxy group, a propionyloxy group, an n-butyryloxy group, a t-butyryloxy group, a t-amylyloxy group, an n-hexanecarbonyloxy group, an n-octanecarbonyloxy group, etc. Among these, an acetoxy group is preferred.

[0121] Examples of the substituted or unsubstituted amino group represented by Y include an amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dipropylamino group, etc. Among these, a dimethylamino group and a diethylamino group are preferred.

[0122] Preferred combinations of a metal atom represented by M and a hydrolyzable group represented by Y are described below. When the metal atom represented by M is tin, the hydrolyzable group represented by Y is preferably a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, or 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 Y is preferably a halogen atom, an alkoxy group, an acyloxy group, or a substituted or unsubstituted amino group. When the metal atom represented by M is hafnium, zirconium, or titanium, the hydrolyzable group represented by Y is preferably a halogen atom, an alkoxy group, or an acyloxy group.

[0123] L 1 The ligand represented by the formula (I) includes a monodentate ligand and a polydentate ligand.

[0124] Examples of the monodentate ligand include a hydroxo ligand, a nitro ligand, and ammonia.

[0125] Examples of the polydentate ligand include hydroxy acid esters, β-diketones, β-ketoesters, malonic acid diesters in which the carbon atom at the α-position may be substituted, and hydrocarbons having a π bond, or ligands derived from these compounds, and diphosphines.

[0126] Examples of the diphosphines include 1,1-bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl, and 1,1′-bis(diphenylphosphino)ferrocene.

[0127] L 1 Examples of the monovalent organic group represented by the formula (1) include R 1 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula: 1 The lower limit of the number of carbon atoms in the monovalent organic group represented by the formula (I) is preferably 2, more preferably 3. On the other hand, the upper limit of the number of carbon atoms is preferably 10, more preferably 5. 1 The monovalent organic group represented by the formula (I) is preferably a substituted or unsubstituted hydrocarbon group, more preferably a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group, further preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted aralkyl group, and particularly preferably an i-propyl group or a benzyl group.

[0128] As a1, 1 and 2 are preferred, and 1 is more preferred.

[0129] b1 is preferably an integer of 2 to 4. By setting b1 to the above value, the content of metal atoms in the [P] metal-containing compound can be increased, and the generation of secondary electrons by the [P] metal-containing compound can be more effectively promoted. As a result, pattern collapse can be more reliably suppressed.

[0130] The metal compound (1) is preferably a metal halide compound, more preferably isopropyltin trichloride or benzyltin trichloride.

[0131] Examples of methods for carrying out the hydrolysis and condensation reaction of metal compound (1) include stirring metal compound (1) in water or a solvent containing water in the presence of a base such as tetramethylammonium hydroxide, which is used as needed. In this case, other compounds having hydrolyzable groups may be added as needed. The lower limit of the amount of water used in this hydrolysis and condensation reaction is preferably 0.2 times by mole, more preferably 1 time by mole, and even more preferably 3 times by mole, relative to the hydrolyzable groups of metal compound (1). By setting the amount of water in the hydrolysis and condensation reaction within the above range, a [P] metal-containing compound can be easily and reliably obtained.

[0132] [P] In the synthesis reaction of the metal-containing compound, in addition to the metal compound (1), L in the compound of the above formula (4) 1 Alternatively, a compound capable of becoming a multidentate ligand represented by the formula (I) or a compound capable of becoming a bridging ligand may be added. Examples of the compound capable of becoming a bridging ligand include compounds having two or more coordinating groups such as a hydroxy group, an isocyanate group, an amino group, an ester group, and an amide group.

[0133] [P] The lower limit of the temperature for the synthesis reaction of the metal-containing compound is preferably 0°C, more preferably 10°C. The upper limit of the temperature is preferably 150°C, more preferably 100°C, and even more preferably 50°C.

[0134] The lower limit of the synthesis reaction time for the metal-containing compound [P] is preferably 1 minute, more preferably 10 minutes, and even more preferably 1 hour.The upper limit of the synthesis reaction time is preferably 100 hours, more preferably 50 hours, even more preferably 24 hours, and particularly preferably 4 hours.

[0135] ([Q] solvent) The solvent [Q] is preferably an organic solvent. Specific examples of this organic solvent include the same solvents as those exemplified as the solvent [B] in the composition for forming a resist underlayer film described above.

[0136] [Q] The solvent is preferably an alcohol solvent, more preferably a monoalcohol solvent, and even more preferably 4-methyl-2-pentanol.

[0137] [Other optional ingredients] The radiation-sensitive composition for forming a resist film may contain other optional components such as a compound that can serve as a ligand, a surfactant, and the like, in addition to the metal-containing compound [P] and the solvent [Q].

[0138] [Potential ligand compounds] Examples of the compound that can serve as the ligand include compounds that can serve as multidentate ligands or bridging ligands, and specific examples include compounds similar to the compounds that can serve as multidentate ligands or bridging ligands exemplified in the synthesis method for the [P] metal-containing compound.

[0139] [Surfactants] Surfactants are components that have the effect of improving coatability, striations, 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 products under the trade names KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and the same No. 95 (all manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products Co., Ltd.), Megafac F171, F173 (manufactured by Dainippon Ink and Chemicals, Inc.), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd.), etc.

[0140] (Method for preparing radiation-sensitive composition for forming a resist film) The radiation-sensitive composition for forming a resist film can be prepared, for example, by mixing the metal-containing compound [P] and, if necessary, other optional components such as the solvent [Q] in a predetermined ratio, and then filtering the resulting mixture through a membrane filter with a pore size of approximately 0.2 μm. When the radiation-sensitive composition for forming a resist film contains the solvent [Q], the lower limit of the solids concentration of the radiation-sensitive composition for forming a resist film is preferably 0.1% by mass, more preferably 0.5% by mass, even more preferably 1% by mass, and particularly preferably 2% by mass. Meanwhile, the upper limit of the solids concentration is preferably 50% by mass, more preferably 30% by mass, even more preferably 15% by mass, and particularly preferably 4% by mass.

[0141] [Exposure process] In this step, the metal-containing resist film formed in the above-mentioned metal-containing resist film-forming composition application step is exposed to electron beams or extreme ultraviolet rays (wavelength 13.5 nm, etc., also known as "EUV"). Specifically, the metal-containing resist film is irradiated with electron beams or extreme ultraviolet rays, for example, through a mask having a predetermined pattern. This step results in a difference in solubility in a developer between the exposed and unexposed areas of the metal-containing resist film. The exposure conditions can be appropriately determined depending on the type of metal-containing resist film-forming composition used, etc.

[0142] In this step, after the exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the metal-containing resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined depending on the type of metal-containing 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.

[0143] [Development process] In this step, the exposed metal-containing resist film is developed. Examples of developers used in this development include an alkaline aqueous solution (alkaline developer) and an organic solvent-containing solution (organic solvent developer). For example, in the case of a positive resist pattern formed using an alkaline developer, the exposed portions of the metal-containing resist film have increased solubility in an alkaline aqueous solution, and thus the exposed portions are removed by alkaline development, forming a positive resist pattern. In the case of a negative resist pattern formed using an organic solvent developer, the exposed portions of the metal-containing resist film have decreased solubility in an organic solvent, and thus the unexposed portions, which have relatively high solubility in an organic solvent, are removed by organic solvent development, forming a negative resist pattern.

[0144] Examples of alkaline aqueous solutions (alkaline developers) 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.

[0145] The lower limit of the alkaline compound content in the alkaline aqueous solution is preferably 0.1% by mass, more preferably 0.5% by mass, and even more preferably 1% by mass, and the upper limit of the content is preferably 20% by mass, more preferably 10% by mass, and even more preferably 5% by mass.

[0146] The alkaline aqueous solution is preferably a TMAH aqueous solution, more preferably a 2.38 mass % TMAH aqueous solution.

[0147] The organic solvent contained in the organic solvent-containing liquid (organic solvent developer) may be any known organic solvent used in organic solvent development, such as those exemplified as the solvent (B) in the composition for forming a resist underlayer film.

[0148] The organic solvent is preferably an ester solvent, an ether solvent, an alcohol solvent, a ketone solvent and / or a hydrocarbon solvent, more preferably a ketone solvent, and particularly preferably 2-heptanone.

[0149] The lower limit of the content of the organic solvent in the organic solvent-containing liquid is preferably 80% by mass, more preferably 90% by mass, even more preferably 95% by mass, and particularly preferably 99% by mass.

[0150] These developers may be used alone or in combination of two or more. After development, the film is generally washed and dried.

[0151] [Etching process] This process involves etching using a resist pattern or the like as a mask. Etching may be performed once or multiple times, i.e., sequentially using the pattern obtained by etching as a mask. However, multiple times is preferred from the viewpoint of obtaining a pattern with a better shape. When performing multiple etching processes, for example, if the organic underlayer film is not present, etching is performed sequentially on the resist underlayer film and then on the substrate. If the organic underlayer film is present, etching is performed sequentially on the resist underlayer film, then on the organic underlayer film, and then on the substrate. Examples of etching methods include dry etching and wet etching. Among these, dry etching is preferred from the viewpoint of obtaining a better pattern shape on the substrate. Examples of etching gases include fluorine-based gases, oxygen-based gases, and the like, which are appropriately selected depending on the materials of the mask and the layer to be etched. For example, fluorine-based gases are typically used for dry etching of a resist underlayer film (silicon-containing film) using a resist pattern as a mask, and a mixture of oxygen-based gases and inert gases is preferably used. Oxygen-based gases are typically used for dry etching of an organic underlayer film using a resist underlayer film (silicon-containing film) pattern as a mask. The substrate is dry-etched using the organic underlayer film pattern as a mask using the same gases and the like as those used in dry-etching the resist underlayer film (silicon-containing film). After the above etching, a patterned substrate having a predetermined pattern is obtained. [Example]

[0152] Examples will be described below. Note that the examples shown below are representative examples of the present invention, and should not be construed as narrowing the scope of the present invention.

[0153] In the present examples, the weight average molecular weight (Mw) of the compound [A], the concentration of the compound [A] in the solution, and the average thickness of the film were measured by the following methods.

[0154] [Measurement of weight average molecular weight (Mw)] The weight-average molecular weight (Mw) of the compound [A] was measured by gel permeation chromatography (GPC) using two GPC columns ("G2000HXL," one "G3000HXL," and one "G4000HXL") manufactured by Tosoh Corporation under the following conditions. Eluent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: differential refractometer Standard material: monodisperse polystyrene

[0155] [[A] Concentration of compound in solution] 0.5 g of the solution of the compound [A] was baked at 250°C for 30 minutes, and the mass of the residue obtained was measured. The mass of this residue was then divided by the mass of the solution of the compound [A] to calculate the concentration of the solution of the compound [A] (unit: mass %).

[0156] [Average film thickness] The average thickness of the film was measured using a spectroscopic ellipsometer (JAWOOLLAM "M2000D").

[0157] <Synthesis of Compound [A]> The monomers used in the synthesis of compound [A] (hereinafter also referred to as "monomers (M-1) to (M-13)") are shown below. In the following Synthesis Examples, Leather Synthesis Examples, and Reference Synthesis Examples, unless otherwise specified, parts by mass refer to a value where the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value where the total number of moles of the monomers used is taken as 100 mol %.

[0158] [ka]

[0159] [Synthesis Example 1] (Synthesis of Compound (A-1)) In a reaction vessel, the above-mentioned monomer (M-1) and monomer (M-4) (total 100 parts by mass) were dissolved in 53 parts by mass of propylene glycol monoethyl ether to a molar ratio of 90 / 10 (mol%) to prepare a monomer solution. The temperature inside the reaction vessel was brought to 5°C, and 49 parts by mass of a 9.1% by mass aqueous oxalic acid solution was added dropwise over 20 minutes while stirring. After the dropwise addition was completed, the reaction vessel was heated to 40°C, and the reaction was carried out for 4 hours. After the reaction was completed, 98 parts by mass of water was added, and the mixture was stirred for 1 hour. After stirring was completed, the reaction vessel was cooled to below 30°C. 375 parts by mass of propylene glycol monoethyl ether was added to the cooled reaction solution, and the 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 compound (A-1). The Mw of compound (A-1) was 1,800. The concentration of the compound (A-1) in the propylene glycol monoethyl ether solution was 10.0% by mass.

[0160] [Synthesis Examples 2 to 12 and Comparative Synthesis Examples 1 to 2] (Synthesis of Compounds (A-2) to (A-12) and Compounds (a-1) to (a-2)) Solutions of compounds (A-2) to (A-12) and compounds (a-1) to (a-2) in propylene glycol monoethyl ether were obtained in the same manner as in Synthesis Example 1, except that the types and amounts (mol %) of each monomer used were as shown in Table 1 below. The Mw of the obtained [A] compound and the concentration (mass %) of [A] compound in the propylene glycol monoethyl ether solution are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0161] [Table 1]

[0162] [Reference Synthesis Example 1] (Synthesis of Compound (a-3)) A nitrogen-purged reaction vessel was charged with 18.61 parts by mass of magnesium and 35 parts by mass of tetrahydrofuran and stirred at 20°C. Next, dibromomethane, trichloromethylsilane, and trichlorohydrosilane (total 100 parts by mass) were dissolved in 355 parts by mass of tetrahydrofuran to give a molar ratio of 50 / 15 / 35 (mol%) to prepare a monomer solution. The temperature inside the reaction vessel was brought to 20°C, and the monomer solution was added dropwise over 1 hour with stirring. The reaction was started at the end of the dropwise addition, and the mixture was reacted at 40°C for 1 hour and then at 60°C for 3 hours. After that, 213 parts by mass of tetrahydrofuran was added, and the mixture was cooled to below 10°C to obtain a polymerization reaction solution. Next, 96.84 parts by mass of triethylamine was added to this polymerization reaction solution, and 30.66 parts by mass of methanol was added dropwise over 10 minutes with stirring. The reaction was started when the dropwise addition was completed. After reacting at 20°C for 1 hour, the reaction solution was poured into 700 parts by mass of diisopropyl ether, and the precipitated salt was filtered off. Next, tetrahydrofuran, excess triethylamine, and excess methanol were removed from the filtrate using an evaporator. The resulting residue was poured into 180 parts by mass of diisopropyl ether, and the precipitated salt was filtered off. Diisopropyl ether was added to the filtrate to obtain 223 g of a diisopropyl ether solution of polycarbosilane (aa-3). The Mw of polycarbosilane (aa-3) was 700.

[0163] A reaction vessel was charged with 100 parts by mass of 223 parts by mass of the diisopropyl ether solution of polycarbosilane (aa-3) and 90 parts by mass of methanol. The temperature inside the reaction vessel was brought to 30°C, and 8 parts by mass of a 3.2% by mass aqueous oxalic acid solution was added dropwise over 20 minutes while stirring. The reaction started when the addition was completed, and the reaction was continued at 40°C for 4 hours, after which the reaction vessel was cooled to 30°C or below. Next, 99 parts by mass of diisopropyl ether and 198 parts by mass of water were added to the reaction vessel, and extraction was performed. After that, 0.26 parts by mass of oxalic acid dihydrate and 396 parts by mass of propylene glycol monomethyl ether were added to the resulting organic layer, and the water, diisopropyl ether, alcohols produced by the reaction, and excess propylene glycol monomethyl ether were removed using an evaporator. Next, 19.82 parts by mass of trimethyl orthoformate as a dehydrating agent was added to the resulting solution, and the mixture was allowed to react at 40°C for 1 hour, after which the reaction vessel was cooled to 30°C or below. 99 parts by mass of propylene glycol monomethyl ether acetate was added to the reaction vessel, and then an evaporator was used to remove the alcohols, esters, trimethyl orthoformate, and excess propylene glycol monomethyl ether acetate produced by the reaction, yielding a propylene glycol monomethyl ether acetate solution of compound (a-3). The Mw of compound (a-3) was 2,500. The concentration of this propylene glycol monomethyl ether acetate solution of compound (a-3) was 5% by mass.

[0164] [Reference Synthesis Example 2] (Synthesis of Compound (a-4)) A propylene glycol monomethyl ether acetate solution of compound (a-4) was obtained in the same manner as in Reference Synthesis Example 1 above, except that the dibromomethane, trichloromethylsilane, and trichlorohydrosilane (molar ratio: 50 / 15 / 35 (mol %), total 100 parts by mass) in Reference Synthesis Example 1 above was replaced with dibromomethane, tetrachlorosilane, trichloromethylsilane, and trichlorohydrosilane (molar ratio: 50 / 5 / 15 / 30 (mol %), total 100 parts by mass). The Mw of compound (a-4) was 2,100. The concentration of this propylene glycol monomethyl ether acetate solution of compound (a-4) was 5% by mass.

[0165] <Preparation of composition for forming resist underlayer film> The solvent [B] and the additive [C] used in the preparation of the composition for forming a resist underlayer film are shown below.

[0166] [[B] Solvent] B-1: Propylene glycol monoethyl ether B-2: Propylene glycol monomethyl ether acetate

[0167] [[C] Additives] C-1: A compound represented by the following formula (C-1): C-2: A compound represented by the following formula (C-2): C-3: A compound represented by the following formula (C-3):

[0168] [ka]

[0169] [Example 1-1] 0.5 parts by mass of (A-1) as the [A] compound (excluding the solvent), 95.5 parts by mass of (B-1) as the [B] solvent (including (B-1) as the solvent contained in the solution of the [A] compound), and 4 parts by mass of water (including the water contained in the solution of the [A] compound) were mixed, and the resulting solution was filtered through a PTFE (polytetrafluoroethylene) filter with a pore size of 0.2 μm to prepare a composition for forming a resist underlayer film (J-1).

[0170] [Examples 1-2 to 1-14, Comparative Examples 1-1 to 1-2, and Reference Examples 1-1 to 1-2] Compositions (J-2) to (J-14) and (j-1) to (j-4) were prepared in the same manner as in Example 1, except that the types and amounts of each component were used as shown in Table 2. In Table 2, "-" indicates that the corresponding component was not used.

[0171] [Table 2]

[0172] <Preparation of Composition for Forming Metal-Containing Resist Film>

[0173] [Synthesis of Compounds] Compounds (S-1) to (S-4) used for the preparation of the composition for forming a metal-containing resist film were synthesized by the following procedures.

[0174] [Synthesis Example 2-1] (Synthesis of Compound (S-1)) In a reaction vessel, while stirring 150 mL of 0.5N aqueous sodium hydroxide solution, 6.5 parts by mass of isopropyltin trichloride was added, and the reaction was carried out for 2 hours. The precipitated 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) is an oxide hydroxide product (i-PrSnO (3 / 2-x / 2) (OH) x (0 < x < 3) as a structural unit).

[0175] [Synthesis Example 2-2] (Synthesis of Compound (S-2)) In a reaction vessel, while stirring 100 mL of 0.5M aqueous tetramethylammonium hydroxide solution, 3.16 parts by mass of benzyltin trichloride was added, and the reaction was carried out for 2 hours. The precipitated precipitate was collected by filtration, washed twice with 50 parts by mass of water, and then dried to obtain Compound (S-2). Compound (S-2) is a compound having a structural unit represented by ((PhCH2)SnO 3 / 2 ).

[0176] [Synthesis Example 2-3] (Synthesis of Compound (S-3)) In a reaction vessel, 20.0 parts by mass of tetrabutoxytin (IV), 100 parts by mass of tetrahydrofuran, and 100 parts by mass of methacrylic acid were added, and the reaction was carried out at 65°C for 20 minutes. Next, 10.6 parts by mass of water was added dropwise over 10 minutes, and the reaction was carried out at 65°C for 18 hours. Next, 10.6 parts by mass of water was added dropwise over 10 minutes, and the mixture was stirred for 2 hours. 400 parts by mass of water was added to the cooled reaction liquid to obtain a precipitate. The obtained precipitate was centrifuged and then dissolved in 50 parts by mass of acetone, and 400 parts by mass of water was added to obtain a precipitate. The obtained precipitate was centrifuged and then dried to obtain compound (S-3). Compound (S-3) is a particle containing methacrylic acid and a metal oxide of tin as the main component.

[0177] [Synthesis Example 2-4] (Synthesis of Compound (S-4)) In a reaction vessel, 20.0 parts by mass of tetraisopropoxyzirconium(IV), 100 parts by mass of tetrahydrofuran, and 100 parts by mass of methacrylic acid were added, and the reaction was carried out at 65°C for 20 minutes. Next, 10.6 parts by mass of water was added dropwise over 10 minutes, and the reaction was carried out at 65°C for 18 hours. Next, 10.6 parts by mass of water was added dropwise over 10 minutes, and the mixture was stirred for 2 hours. 400 parts by mass of water was added to the cooled reaction liquid to obtain a precipitate. The obtained precipitate was centrifuged and then dissolved in 50 parts by mass of acetone, and 400 parts by mass of water was added to obtain a precipitate. The obtained precipitate was centrifuged and then dried to obtain compound (S-4). Compound (S-4) is a particle containing zirconium metal oxide as a main component and methacrylic acid.

[0178] [Preparation of Metal-Containing Resist Film-Forming Composition] [Preparation Example 2-1] Two parts by mass of the compound (S-1) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the resulting mixture was passed through an activated 4 Å molecular sieve to remove residual water, followed by filtration through a filter with a pore size of 0.2 μm to prepare a composition for forming a metal-containing resist film (K-1).

[0179] [Preparation Example 2-2] 2 parts by mass of the compound (S-2) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the resulting solution was filtered through a filter with a pore size of 0.2 μm to prepare a composition for forming a metal-containing resist film (K-2).

[0180] [Preparation Example 2-3] Two parts by mass of the compound (S-3) synthesized above, 98 parts by mass of propylene glycol monoethyl ether, and 0.2 parts by mass of N-trifluoromethanesulfonyloxy-5-norbornene-2,3-dicarboximide were mixed, and the resulting solution was filtered through a filter with a pore size of 0.2 μm to prepare a composition for forming a metal-containing resist film (K-3).

[0181] [Preparation Example 2-4] 2 parts by mass of the compound (S-4) synthesized above, 98 parts by mass of propylene glycol monoethyl ether, and 0.2 parts by mass of N-trifluoromethanesulfonyloxy-5-norbornene-2,3-dicarboximide were mixed, and the resulting solution was filtered through a filter with a pore size of 0.2 μm to prepare a composition for forming a metal-containing resist film (K-4).

[0182] <Evaluation> [Examples 2-1 to 2-29, Comparative Examples 2-1 to 2-8, and Reference Examples 1-1 to 1-2] Each of the prepared compositions for forming a resist underlayer film and each of the prepared compositions for forming a metal-containing resist film was used to evaluate the ability to inhibit collapse of the resist pattern by the following method. The evaluation results are shown in Table 3 below.

[0183] [Resist pattern collapse prevention] An organic underlayer film forming material (JSR Corporation's "HM8006") was applied to a 12-inch silicon wafer by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), followed by heating 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 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 10 nm. The metal-containing resist film forming composition shown in Table 3 below was applied to this resist underlayer film by spin coating using the spin coater. After a predetermined time had elapsed, the composition was heated at 90°C for 60 seconds and then cooled at 23°C for 30 seconds to form a metal-containing resist film with an average thickness of 35 nm. The metal-containing resist film was exposed to light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line-and-space mask with a line width of 25 nm on the wafer). After exposure, the substrate was heated at 110°C for 60 seconds and then cooled at 23°C for 60 seconds. Subsequently, the substrate was developed using 2-heptanone (20-25°C) by the puddle method and then dried to obtain an evaluation substrate on which a resist pattern was formed. A scanning electron microscope (Hitachi High-Tech's "CG-6300") was used to measure and observe the resist pattern of the evaluation substrate.

[0184] Resist pattern collapse suppression: If no collapse of the resist pattern of the 18 nm line width was confirmed, the result was "A" (very good). If the resist pattern collapse of the 18 nm line width was confirmed, but the resist pattern collapse of the 24 nm line width was not confirmed, the result was "B" (good). When collapse of the resist pattern of a line with a line width of 24 nm was confirmed, it was evaluated as "C" (poor).

[0185] [Table 3]

[0186] As is clear from the results in Table 3 above, each of the compositions for forming a resist underlayer film in the Examples had good properties for inhibiting the collapse of the resist pattern. [Industrial Applicability]

[0187] The composition for forming a resist underlayer film of the present invention can be suitably used in the production of semiconductor substrates, etc.

Claims

1. A composition for forming a resist underlayer film used to form an underlayer film of a metal-containing resist film in electron beam or extreme ultraviolet lithography, comprising: a polysiloxane compound having a first structural unit represented by the following formula (1); Solvent and Contains The metal-containing resist film is formed from a composition for forming a resist underlayer film, which contains a metal-containing compound in an amount of 50% by mass or more in terms of solid content. 【Chemistry 1】 (In formula (1), X is a hydroxyalkyl group, an organic group having a carbonate structure, an organic group having an acyl group, an organic group having a carboxylic acid anhydride group, a group represented by the following formula (1-1) or a group represented by the following formula (1-2). 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. １ is a group other than X. 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. 【Chemistry 2】 (In formula (1-1) and formula (1-2), R ２ and R ４ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. n is 1 or 2. When n is 2, multiple R ２ are the same or different. ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. L is a single bond or a divalent linking group. * indicates the bonding site with the silicon atom in the above formula (1).

2. 2. The composition for forming a resist underlayer film according to claim 1, wherein the polysiloxane compound further comprises a second structural unit represented by the following formula (2): 【Transformation 3】 (In the above formula (2), R ５ 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 R ５ are the same or different.)

3. 3. The composition for forming a resist underlayer film according to claim 1, wherein the content of the first structural unit relative to all structural units constituting the polysiloxane compound is 1 mol % or more and 40 mol % or less.

4. a step of directly or indirectly applying the composition for forming a resist underlayer film according to claim 1 to a substrate; a step of applying a composition for forming a metal-containing resist film, the composition containing a metal-containing compound in an amount of 50% by mass or more in terms of solid content, to the resist underlayer film formed in the step of applying the composition for forming a resist underlayer film; a step of exposing the metal-containing resist film formed by the metal-containing resist film-forming composition coating step to electron beams or extreme ultraviolet rays; developing the exposed metal-containing resist film; A method for manufacturing a semiconductor substrate, comprising:

5. Before the step of applying the composition for forming a resist underlayer film, A step of forming an organic underlayer film directly or indirectly on the substrate. The method for manufacturing a semiconductor substrate according to claim 4 , further comprising:

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