Production method for semiconductor substrate, resist underlayer film formation composition, and production method for nitrogen-containing compound

Abstract

Provided are a production method for a semiconductor substrate that uses a composition that makes it possible to form a film that has excellent flatness and embedding properties, a resist underlayer film formation composition, and a production method for a nitrogen-containing compound. According to the present invention, a production method for a semiconductor substrate includes a step for applying a resist underlayer film formation composition directly or indirectly to a substrate, a step for forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step, and a step for performing etching that forms a mask from the resist pattern. The resist underlayer film formation composition contains a nitrogen-containing compound and a solvent. The nitrogen-containing compound is a compound represented by formula (A1), formula (A2), or formula (A3) or a polymer that has a repeating unit represented by formula (A4) or formula (A5).

Description

Manufacturing method for semiconductor substrate, composition for forming resist underlayer film, and manufacturing method for nitrogen-containing compound

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

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

[0003] Various studies have been conducted on materials used in such compositions for forming resist underlayer films (Japanese Patent No. 6923301).

[0004] Patent No. 6923301

[0005] Recently, substrates on which patterns such as trenches and holes are formed have been increasingly used, and a composition for forming a resist underlayer film is required to have embedding properties that allow it to be sufficiently embedded in the substrate pattern and flatness that allows it to form a flat film regardless of the presence or absence of a pattern.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a method for producing a semiconductor substrate using a composition capable of forming a film having excellent embedding properties and flatness, a composition for forming a resist underlayer film, and a method for producing a nitrogen-containing compound.

[0007] In one embodiment, the present invention relates to a method for producing a semiconductor substrate, the method comprising: applying a composition for forming a resist underlayer film directly or indirectly onto a substrate; forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step; and performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains a nitrogen-containing compound (hereinafter also referred to as "compound [A]") and a solvent (hereinafter also referred to as "solvent [B]"), and the nitrogen-containing compound is a compound represented by the following formula (A1), (A2), or (A3) (hereinafter also referred to as "compound [A1]"), or a polymer having a repeating unit represented by the following formula (A4) or (A5) (hereinafter also referred to as "polymer [A4]"): (In formulas (A1) to (A5), s is an integer of 1 to 4. When s is 2 or more, a plurality of R ａ , Ar and X are the same or different. ａ is a monovalent organic group having 1 to 40 carbon atoms. Each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. W １ When s is 1, 3, or 4, W is an s-valent organic group having 1 to 40 carbon atoms, and when s is 2, W is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent heteroatom-containing linking group. Each X is independently O, S, or NR'. R' is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. W ２ is a t-valent organic group having 1 to 40 carbon atoms. t is an integer of 1 to 4. When t is 2 or more, the plurality of Ar's and X's are the same or different from each other. R ｂ are each independently a monovalent organic group having 1 to 40 carbon atoms. ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. u1 and u2 are each independently an integer of 0 to 4, provided that u1+u2 is 2 or more. ｂ and X are the same or different from each other. ３１ is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent linking group containing a hetero atom. ３２and W ４ are each independently a divalent organic group having 1 to 40 carbon atoms. ｃ is a monovalent organic group having 1 to 40 carbon atoms.

[0008] According to this semiconductor substrate manufacturing method, by using a predetermined resist underlayer film-forming composition in the coating step, a resist underlayer film with excellent filling ability and flatness can be formed, thereby enabling the production of a semiconductor substrate with a good pattern shape. While the reason for this is unclear, it is presumed as follows: The compound [A] incorporates a rigid and chemically stable specific structure in which a five-membered heterocycle containing two heteroatoms and an aromatic ring are condensed, either as a monomolecular [A1] compound or as an [A2] polymer containing two of the specific structure in a repeating unit. This allows the incorporation density of the specific structure in the compound [A] to be increased, thereby improving heat resistance. As a result, it is presumed that the occurrence of voids and film shrinkage in the film during heating can be prevented, and as a result, the resist underlayer film-forming composition can form a resist underlayer film with excellent filling ability and flatness.

[0009] In another embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a nitrogen-containing compound; and a solvent, wherein the nitrogen-containing compound is a compound represented by the following formula (A1), (A2), or (A3), or a polymer having a repeating unit represented by the following formula (A4) or (A5): (In formulas (A1) to (A5), s is an integer of 1 to 4. When s is 2 or more, a plurality of R ａ , Ar and X are the same or different. ａ is a monovalent organic group having 1 to 40 carbon atoms. Each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. W １ When s is 1, 3, or 4, W is an s-valent organic group having 1 to 40 carbon atoms, and when s is 2, W is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent heteroatom-containing linking group. Each X is independently O, S, or NR'. R' is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. W２ is a t-valent organic group having 1 to 40 carbon atoms. t is an integer of 1 to 4. When t is 2 or more, the plurality of Ar's and X's are the same or different from each other. R ｂ are each independently a monovalent organic group having 1 to 40 carbon atoms. ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. u1 and u2 are each independently an integer of 0 to 4, provided that u1+u2 is 2 or more. ｂ and X are the same or different from each other. ３１ is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent linking group containing a hetero atom. ３２ and W ４ are each independently a divalent organic group having 1 to 40 carbon atoms. ｃ is a monovalent organic group having 1 to 40 carbon atoms.

[0010] In yet another embodiment, the present invention relates to a method for producing a nitrogen-containing compound, the method comprising a step of reacting a compound represented by the following formula (a1), (a2), or (a3) ​​(hereinafter also referred to as "compound [a]") with a compound represented by the following formula (b) (hereinafter also referred to as "compound [b]"): (In formulas (a1) to (a3), each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. Ar ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. １ is an s-valent organic group having 1 to 40 carbon atoms. Each X is independently O, S, or NH. s is an integer of 1 to 4. Each of u1 and u2 is independently an integer of 0 to 4, provided that u1+u2 is 2 or more. In formula (b), W ２ is a t-valent organic group having 1 to 40 carbon atoms. ｘ and R ｙ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, and t is an integer of 1 to 4.

[0011] As used herein, the term "fused ring" refers to a polycyclic structure formed by adjacent rings sharing one side (two adjacent atoms). The term "organic group" refers to a group containing at least one carbon atom.

[0012] According to the method for producing a semiconductor substrate, a resist underlayer film having excellent filling properties and flatness can be formed, thereby obtaining a semiconductor substrate having a good pattern shape. According to the composition for forming a resist underlayer film, a film having excellent filling properties and flatness can be formed. According to the method for producing a nitrogen-containing compound, a nitrogen-containing compound suitable as a component of the composition for forming a resist underlayer film can be efficiently produced. Therefore, these compounds can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0013] FIG. 10 is a schematic plan view for explaining a method for evaluating flatness.

[0014] The method for producing a semiconductor substrate, the composition for forming a resist underlayer film, and the method for producing a nitrogen-containing compound according to each embodiment of the present invention will be described in detail below. Combinations of preferred embodiments are also preferred.

[0015] <<Method for Manufacturing Semiconductor Substrate>> The method for manufacturing a semiconductor substrate includes a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate (hereinafter also referred to as a “coating step”), a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step (hereinafter also referred to as a “resist pattern forming step”), and a step of performing etching using the resist pattern as a mask (hereinafter also referred to as an “etching step”).

[0016] The method for manufacturing a semiconductor substrate may further include, as necessary, a step of heating the resist underlayer film formed in the coating step (hereinafter also referred to as a "heating step") before the resist pattern forming step.

[0017] The method for producing a semiconductor substrate may further include, as necessary, a step of forming a silicon-containing film directly or indirectly on the resist underlayer film before forming the resist pattern (hereinafter also referred to as a "silicon-containing film forming step").

[0018] The composition for forming a resist underlayer film used in the method for producing a semiconductor substrate and each step will be described below.

[0019] <Composition for forming a resist underlayer film> The composition for forming a resist underlayer film contains the compound [A] and the solvent [B]. The composition for forming a resist underlayer film may contain any optional component within a range that does not impair the effects of the present invention.

[0020] Hereinafter, each component contained in the composition for forming a resist underlayer film will be described.

[0021] <Compound [A]> The compound [A] is a compound represented by the following formula (A1), (A2), or (A3), or a polymer having a repeating unit represented by the following formula (A4) or (A5). The composition for forming a resist underlayer film may contain one or more types of compound [A]. The polymer [A4] may have one or two or more types of repeating units represented by the following formula (A4). The polymer [A5] may have one or two or more types of repeating units represented by the following formula (A5). (In formulas (A1) to (A5), s is an integer of 1 to 4. When s is 2 or more, a plurality of R ａ , Ar and X are the same or different. ａ is a monovalent organic group having 1 to 40 carbon atoms. Each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. W １ When s is 1, 3, or 4, W is an s-valent organic group having 1 to 40 carbon atoms, and when s is 2, W is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent heteroatom-containing linking group. Each X is independently O, S, or NR'. R' is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. W ２ is a t-valent organic group having 1 to 40 carbon atoms. t is an integer of 1 to 4. When t is 2 or more, the plurality of Ar's and X's are the same or different from each other. R ｂ are each independently a monovalent organic group having 1 to 40 carbon atoms. ｘis a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. u1 and u2 are each independently an integer of 0 to 4, provided that u1+u2 is 2 or more. ｂ and X are the same or different from each other. ３１ is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent linking group containing a hetero atom. ３２ and W ４ are each independently a divalent organic group having 1 to 40 carbon atoms. ｃ is a monovalent organic group having 1 to 40 carbon atoms.

[0022] In the above formula (A1), R ａ Examples of the monovalent organic group having 1 to 40 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 40 carbon atoms, a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the terminal of the hydrocarbon group (hereinafter also referred to as "group (α)"), a group in which some or all of the hydrogen atoms of the hydrocarbon group or the group (α) have been substituted with a monovalent heteroatom-containing substituent, or a group comprising a combination thereof.

[0023] Examples of the monovalent hydrocarbon group having 1 to 40 carbon atoms include a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms, or a group formed by combining these groups.

[0024] Examples of the monovalent chain hydrocarbon group having 1 to 40 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a s-butyl group, and a t-butyl group; alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0025] Examples of the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms include cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group; cycloalkenyl groups such as a cyclopropenyl group, a cyclopentenyl group and a cyclohexenyl group; bridged ring saturated hydrocarbon groups such as a norbornyl group, an adamantyl group and a tricyclodecyl group; and bridged ring unsaturated hydrocarbon groups such as a norbornenyl group and a tricyclodecenyl group.

[0026] Examples of the monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, and a fluorenyl group; and aralkyl groups such as a benzyl group and a phenethyl group.

[0027] Examples of heteroatoms constituting the divalent heteroatom-containing linking group or 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.

[0028] Examples of the divalent heteroatom-containing linking group include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ -, and combinations thereof. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

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

[0030] R ａ is preferably a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ａExamples of the aromatic ring in the above formula include aromatic hydrocarbon rings having 6 to 40 carbon atoms, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, a perylene ring, a coronene ring, and a biphenyl ring; aromatic heterocyclic rings having 3 to 40 carbon atoms, such as a triazole ring, an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring; and combinations thereof. The combination of these rings may be a fused ring, a ring assembly (a structure in which two rings are bonded by a single bond), or a spiro structure. ａ The aromatic ring is preferably at least one aromatic hydrocarbon ring selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, and a biphenyl ring, and more preferably a naphthalene ring, a pyrene ring, a fluorene ring, or a biphenyl ring.

[0031] R ａ When the aromatic ring in the formula (I) has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an amino group; an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an ethenyl group (vinyl group), an ethynyl group, or a group in which a hydrogen atom of any of these groups has been substituted with a halogen atom; an oxo group (═O); or a group in which any of these groups has been combined.

[0032] R ａ Examples of the monovalent group containing an aromatic ring having 3 to 40 carbon atoms and represented by the following formula include groups in which one hydrogen atom has been removed from the above aromatic ring.

[0033] In the above formulas (A1) to (A2) and (A4) to (A5), the aromatic ring having 3 to 40 carbon atoms in Ar is R in the above formula (A1). ａAmong these, the aromatic ring having 3 to 40 carbon atoms in Ar is preferably a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, or a biphenyl ring, and more preferably a benzene ring or a naphthalene ring.

[0034] In the above formula (A1), W １ The s-valent organic group having 1 to 40 carbon atoms represented by the formula (A1) is ａ A group in which s-1 hydrogen atoms have been removed from a monovalent organic group having 1 to 40 carbon atoms, represented by the following formula:

[0035] W １ is preferably a substituted or unsubstituted s-valent hydrocarbon group having 1 to 40 carbon atoms or a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group. １ The s-valent hydrocarbon group having 1 to 40 carbon atoms in the formula (A1) is ａ A group obtained by removing s hydrogen atoms from a hydrocarbon corresponding to the monovalent hydrocarbon group having 1 to 40 carbon atoms shown in the above formula can be suitably used. As the hydrocarbon group having 1 to 40 carbon atoms, a hydrocarbon corresponding to the monovalent chain hydrocarbon having 1 to 40 carbon atoms, an aromatic hydrocarbon corresponding to the monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms, or a combination thereof is preferred, a chain saturated hydrocarbon corresponding to the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, an aromatic hydrocarbon corresponding to the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof is more preferred, and ethane, propane, butane, benzene, naphthalene, fluorene, or a combination thereof is even more preferred. １ As the divalent heteroatom-containing linking group in the formula (A1), ａ The divalent heteroatom-containing linking group shown in the following formula can be preferably used.

[0036] W １ In the case where the s-valent hydrocarbon group having 1 to 40 carbon atoms has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0037] s is preferably an integer of 1 to 3, more preferably 2 or 3, and even more preferably 2.

[0038] W when s is 2 １ As the divalent heteroatom-containing linking group represented by the formula (A1), ａ The divalent heteroatom-containing linking group shown in the following formula can be preferably used.

[0039] In the above formulas (A1) to (A5), X is preferably O.

[0040] In the above formula (A2), W ２ The t-valent organic group having 1 to 40 carbon atoms and represented by the formula (A1) is ａ A group in which t-1 hydrogen atoms have been removed from a monovalent organic group having 1 to 40 carbon atoms, represented by the following formula:

[0041] W ２ is preferably a substituted or unsubstituted t-valent hydrocarbon group having 1 to 40 carbon atoms or a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group. ２ The t-valent hydrocarbon group having 1 to 40 carbon atoms in the formula (A1) is ａ A group obtained by removing t hydrogen atoms from a hydrocarbon corresponding to the monovalent hydrocarbon group having 1 to 40 carbon atoms shown in the above formula can be suitably used. As the hydrocarbon group having 1 to 40 carbon atoms, a hydrocarbon corresponding to the monovalent chain hydrocarbon having 1 to 40 carbon atoms, an aromatic hydrocarbon corresponding to the monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms, or a combination thereof is preferred, a chain saturated hydrocarbon corresponding to the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, an aromatic hydrocarbon corresponding to the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof is more preferred, and ethane, propane, butane, benzene, naphthalene, fluorene, or a combination thereof is even more preferred. ２ As the divalent heteroatom-containing linking group in the formula (A1), ａ The divalent heteroatom-containing linking group shown in the following formula can be preferably used.

[0042] W ２In the case where the t-valent hydrocarbon group having 1 to 40 carbon atoms has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0043] t is preferably an integer of 1 to 3, and more preferably 2 or 3.

[0044] In the above formula (A3), R ｂ The monovalent organic group having 1 to 40 carbon atoms represented by the formula (A1) is R ａ A monovalent organic group having 1 to 40 carbon atoms and represented by the following formula can be suitably used.

[0045] R ｂ are preferably each independently a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ｂ Examples of the monovalent group containing an aromatic ring having 3 to 40 carbon atoms and represented by the formula (A1) include R ａ A monovalent group containing an aromatic ring having 3 to 40 carbon atoms, as shown in the following formula, can be suitably used.

[0046] Ar ｘ As the aromatic ring having 4 to 40 carbon atoms in the above formula (A1), ａ Of the aromatic rings having 3 to 40 carbon atoms shown above, structures corresponding to 4 to 40 carbon atoms can be suitably employed.

[0047] Ar ｘ When the aromatic ring in the formula (A1) has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0048] Each of u1 and u2 is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and even more preferably 1 or 2.

[0049] In the above formulas (A4) and (A5), W ３１ , W ３２ and W ４ The divalent organic group having 1 to 40 carbon atoms represented by the formula (A1) is R ａA group in which one hydrogen atom has been removed from a monovalent organic group having 1 to 40 carbon atoms, represented by the following formula:

[0050] In the above formula (A4), W ３１ As the divalent heteroatom-containing linking group represented by the formula (A1), ａ The divalent heteroatom-containing linking group shown in the following formula can be preferably used.

[0051] W ３１ , W ３２ and W ４ are preferably each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 40 carbon atoms or a group having the above-mentioned divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group. ３１ , W ３２ and W ４ As the divalent hydrocarbon group having 1 to 40 carbon atoms in the formula (A1), R ａ A group in which one hydrogen atom has been removed from a monovalent hydrocarbon group having 1 to 40 carbon atoms, as shown in the following formula, can be preferably used. ３１ , W ３２ and W ４ are each independently preferably a group obtained by removing one hydrogen atom from the above-mentioned monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a group obtained by removing one hydrogen atom from the above-mentioned monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms, or a combination thereof; more preferably a group obtained by removing one hydrogen atom from a monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, a group obtained by removing one hydrogen atom from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof; and even more preferably an ethanediyl group, a propanediyl group, a butanediyl group, a benzenediyl group, a naphthalenediyl group, a fluorenediyl group, or a combination thereof.

[0052] W ３１ , W ３２ and W ４ When the divalent hydrocarbon group having 1 to 40 carbon atoms in the formula (A1) has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0053] In the above formula (A5), R ｃThe monovalent organic group having 1 to 40 carbon atoms represented by the formula (A1) is R ａ A monovalent organic group having 1 to 40 carbon atoms and represented by the following formula can be suitably used.

[0054] R ｃ is preferably a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ｂ Examples of the monovalent group containing an aromatic ring having 3 to 40 carbon atoms and represented by the formula (A1) include R ａ A monovalent group containing an aromatic ring having 3 to 40 carbon atoms, as shown in the following formula, can be suitably used.

[0055] R ｃ When the aromatic ring in the formula (A1) has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0056] Specific examples of the compound [A1] include, but are not limited to, the following formulae (A1-1) to (A1-15).

[0057]

[0058]

[0059]

[0060] Specific examples of the compound [A2] include, but are not limited to, the following formulae (A2-1) to (A2-6).

[0061]

[0062]

[0063] Specific examples of the compound [A3] include, but are not limited to, the following formulae (A3-1) and (A3-2).

[0064]

[0065] Specific examples of the polymer [A4] include, but are not limited to, polymers having repeating units represented by the following formulas (A4-1) to (A4-10).

[0066]

[0067]

[0068] Specific examples of the compound [A5] include, but are not limited to, the following formulae (A5-1) to (A5-10).

[0069]

[0070]

[0071]

[0072] The molecular weight of the [A] compound is preferably 500 or more, regardless of whether the [A] compound is an [A1] compound, an [A2] compound, an [A3] compound, an [A4] polymer, or an [A5] polymer. When the [A] compound is an [A1] compound, an [A2] compound, or an [A3] compound, the lower limit of the molecular weight of the [A1] compound, the [A2] compound, or the [A3] compound is more preferably 550, and even more preferably 600. The upper limit of the molecular weight is preferably 1500, and even more preferably 1200. When the [A] compound is an [A4] polymer or an [A5] polymer, the lower limit of the molecular weight of the [A4] polymer or the [A5] polymer is more preferably 1500, and even more preferably 2000. The upper limit of the molecular weight of the [A1] compound is preferably 8000, and even more preferably 7000. The molecular weight of the [A1] compound, the [A2] compound, or the [A3] compound is a value calculated from the structural formula. The molecular weight of the polymer [A4] or the polymer [A5] is a weight average molecular weight measured by gel permeation chromatography using monodisperse polystyrene as a standard.

[0073] The content of the compound [A] in the components other than the solvent in the composition for forming a resist underlayer film is preferably 1% by mass or more. The content of the compound [A] may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0074] <Method for Producing Compound [A]> The method for producing compound [A] includes a step of reacting compound [a] with compound [b]. In this production method, compound [A] can be produced simply and efficiently by a two-component cyclocondensation reaction between compound [a] having adjacent hydroxy groups, amino groups, or sulfanyl groups and an amino group, and compound [b] having an amide group.

[0075] (Compound [a]) The compound [a] is a compound represented by the following formula (a1), (a2), or (a3) ​​(hereinafter, each may be referred to as "compound [a1]" or the like). (In formulas (a1) to (a3), each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. Ar ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. １ is an s-valent organic group having 1 to 40 carbon atoms. Each X is independently O, S, or NH. s is an integer of 1 to 4. u1 and u2 are each independently an integer of 0 to 4, provided that u1 + u2 is 2 or greater.

[0076] The aromatic ring having 3 to 40 carbon atoms in Ar in the above formulas (a1) and (a2) includes R in the above formula (A1). ａ In the case where Ar in the above formulas (a1) and (a2) has a substituent, the substituent may be an aromatic ring such as R in the above formula (A1). ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0077] Ar in the above formula (a3)ｘ As the aromatic ring having 4 to 40 carbon atoms in the above formula (A1), ａ Among the aromatic rings having 3 to 40 carbon atoms shown in the above, a structure corresponding to a carbon number of 4 to 40 can be suitably adopted. ｘ When the aromatic ring in the formula (A1) has a substituent, the substituent may be R ａ The substituents that the aromatic ring in the above formula may have can be suitably employed.

[0078] In the above formula (a2), W １ The s-valent organic group having 1 to 40 carbon atoms and represented by the formula (A1) is preferably W １ An s-valent organic group having 1 to 40 carbon atoms and represented by the following formula can be suitably used.

[0079] In the above formulas (a1) to (a3), X is preferably O.

[0080] In the above formula (a2), s is preferably an integer of 1 to 3, more preferably 2 or 3, and even more preferably 2.

[0081] In the above formula (a3), u1 and u2 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2, and more preferably 1 or 2.

[0082] Specific examples of the compound [a1] include, but are not limited to, the following formulae (a1-1) to (a1-3).

[0083]

[0084] Specific examples of the compound [a2] include, but are not limited to, the following formulae (a2-1) to (a2-8).

[0085]

[0086] Specific examples of the compound [a3] include, but are not limited to, the following formulae (a3-1) and (a3-2).

[0087]

[0088] (Compound [b]) The compound [b] is a compound represented by the following formula (b). (In formula (b), W ２ is a t-valent organic group having 1 to 40 carbon atoms. ｘ and R ｙ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, and t is an integer of 1 to 4.

[0089] In the above formula (b), W ２ The t-valent organic group having 1 to 40 carbon atoms and represented by the formula (A2) is preferably W ２ A t-valent organic group having 1 to 40 carbon atoms and represented by the following formula can be suitably used.

[0090] R ｘ and R ｙ The monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (A1) is ａ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms shown in the above, groups having 1 to 10 carbon atoms can be preferably used. ｘ and R ｙ As the alkyl group, a methyl group or an ethyl group is preferred, and a methyl group is more preferred.

[0091] t is preferably an integer of 1 to 3, and more preferably 2 or 3.

[0092] Specific examples of the compound [b] include, but are not limited to, those represented by the following formulae (b-1) to (b-19).

[0093]

[0094]

[0095] The compound [b] may be commercially available or may be synthesized by reacting a carboxylic acid with thionyl chloride and then reacting it with a dialkylamine.

[0096] The reaction between compound [a] and compound [b] can be carried out in a reaction solvent, preferably under an inert gas atmosphere such as a nitrogen gas atmosphere, according to a known method. Typically, compound [a] and compound [b] can be mixed and heated to carry out a batchwise reaction. The molar ratio of compound [a] and compound [b] used in the reaction can be appropriately set, taking into consideration the number of combinations of two adjacent functional groups in compound [a] and the number of amide groups in compound [b]. The lower limit of the reaction temperature is preferably 80°C, and more preferably 100°C. The upper limit of the reaction temperature is preferably 200°C, and more preferably 180°C. The reaction temperature may be set to a temperature at which the solvent refluxes. The lower limit of the reaction time is preferably 1 hour, more preferably 2 hours, and more preferably 5 hours. The upper limit of the reaction time is preferably 36 hours, more preferably 24 hours, and more preferably 20 hours. A catalyst such as imidazole hydrochloride may be added during the reaction. After the reaction, compound [A] can be obtained through separation, purification, drying, etc. The reaction solvent can preferably be the solvent [B] described below.

[0097] The method for producing the compound [A] may further include a step of reacting 1.5 to 2.5 moles of a compound represented by formula (a1) above with 1 mole of a compound represented by formula (b) where t is 2 to produce a cyclized product (typically a unit having a benzoxazole analog at both ends), and then reacting the cyclized product with an aldehyde compound, an aldehyde equivalent, or a methylol compound (hereinafter collectively referred to as "aldehyde compound, etc."). A novolac-type polymer [A5] can be suitably produced by acid addition condensation of the cyclized product with an aldehyde compound. Furthermore, after producing the cyclized product, a substituent may be introduced into the cyclized product. For example, fluorene can be introduced as a substituent by reacting with fluorenol.

[0098] The cyclized product can be produced by the reaction of the compound [a] with the compound [b] described above.

[0099] Specific examples of the cyclized product include, but are not limited to, the following formulae (c-1) to (c-5).

[0100]

[0101] The aldehyde compound is not particularly limited, but is preferably an aromatic ring-containing aldehyde compound, an aromatic ring-containing aldehyde equivalent, or an aromatic ring-containing methylol compound. The aromatic ring in these compounds is preferably R ａ An aromatic ring having 3 to 40 carbon atoms as shown in the following formula can be suitably used.

[0102] Specific examples of the aldehyde compounds include, but are not limited to, those represented by the following formulae (d-1) to (d-9).

[0103]

[0104] The acid addition condensation of the cyclized product with an aldehyde compound or the like may be carried out according to a known method. Preferably, the reaction can be carried out in a reaction solvent under an inert gas atmosphere such as a nitrogen gas atmosphere. The lower limit of the reaction temperature is preferably 40°C, and more preferably 50°C. The upper limit of the reaction temperature is preferably 120°C, and more preferably 80°C. The reaction temperature may be set to a temperature at which the solvent refluxes. The lower limit of the reaction time is preferably 1 hour, more preferably 2 hours, and more preferably 5 hours. The upper limit of the reaction time is preferably 36 hours, more preferably 24 hours, and more preferably 20 hours. An acid catalyst may be added during the reaction. The acid catalyst is not particularly limited, and known inorganic and organic acids can be used. After the reaction, compound [A] can be obtained through separation, purification, drying, and the like. The solvent [B] described below can be suitably used as the reaction solvent.

[0105] <Solvent (B)> The solvent (B) is not particularly limited as long as it can dissolve or disperse the compound (A) and any optional components contained as needed.

[0106] Examples of the solvent (B) include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, etc. The solvent (B) can be used alone or in combination of two or more.

[0107] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0108] Examples of ester-based solvents include carbonate-based solvents such as diethyl carbonate, acetate monoester-based solvents such as methyl acetate and ethyl acetate, lactone-based solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate-based solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate-based solvents such as methyl lactate and ethyl lactate.

[0109] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, and 1-butanol, and polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0110] Examples of the ketone solvent include chain ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and cyclic ketone solvents such as cyclohexanone.

[0111] Examples of ether solvents include chain ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran and dioxane, polyhydric alcohol ether solvents such as ethylene glycol dimethyl ether, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether.

[0112] Examples of nitrogen-containing solvents include chain nitrogen-containing solvents such as N,N-dimethylacetamide and N,N-dimethylformamide, and cyclic nitrogen-containing solvents such as N-methyl-2-pyrrolidone.

[0113] The solvent (B) is preferably an ester-based solvent or a ketone-based solvent, more preferably a polyhydric alcohol partial ether carboxylate-based solvent or a cyclic ketone-based solvent, and even more preferably propylene glycol monomethyl ether acetate or cyclohexanone.

[0114] The lower limit of the content of the solvent (B) in the composition for forming a resist underlayer film is preferably 50% by mass, more preferably 60% by mass, and still more preferably 70% by mass, and the upper limit of the content is preferably 99.9% by mass, more preferably 99% by mass, and still more preferably 95% by mass.

[0115] [Optional Components] The composition for forming a resist underlayer film may contain optional components within the range that does not impair the effects of the present invention. Examples of optional components include acid generators, crosslinking agents, surfactants, dehydrating agents, acid diffusion controllers, base generators, and antifoaming agents. Specific examples of base generators include "U-CAT (registered trademark) SA1", "U-CAT (registered trademark) SA102", "U-CAT (registered trademark) SA102-50", "U-CAT (registered trademark) SA106", "U-CAT (registered trademark) SA112", "U-CAT (registered trademark) SA506", "U-CAT (registered trademark) SA603", "U-CAT (registered trademark) SA1000", "U-CAT (registered trademark) SA1102", "U-CAT (registered trademark) SA2000", and "U-CAT (registered trademark) SA603". Examples of such polyimide polymers include "U-CAT (registered trademark) 2024," "U-CAT (registered trademark) 2026," "U-CAT (registered trademark) 2030," "U-CAT (registered trademark) 2110," "U-CAT (registered trademark) 2313," "U-CAT (registered trademark) 651M," "U-CAT (registered trademark) 660M," "U-CAT (registered trademark) 18X," "TMED," "U-CAT (registered trademark) 201G," "U-CAT (registered trademark) 202," "U-CAT (registered trademark) 420A," "U-CAT (registered trademark) 130," "U-CAT 891 (registered trademark)," "POLYCAT (registered trademark) 8," "POLYCAT (registered trademark) 9," "POLYCAT (registered trademark) 12," and "POLYCAT (registered trademark) 41" (all of which are trade names manufactured by San-Apro Ltd.). As the defoaming agent, known defoaming agents can be used, including alcohol defoaming agents, phosphate ester defoaming agents, fatty acid ester defoaming agents, polyether defoaming agents, and silicone defoaming agents. Examples of fatty acid ester defoaming agents include methyl laurate, methyl palmitate, methyl stearate, propyl butyrate, butyl butyrate, ethyl isovalerate, and isobutyl propionate, with propyl butyrate and butyl butyrate being preferred. Ketone solvents such as 2-heptanone may also be used as the defoaming agent. The optional components can be used alone or in combination of two or more. The content of the optional components in the composition for forming a resist underlayer film can be appropriately determined depending on the type of the optional component, etc.

[0116] [Method for Preparing Composition] The composition for forming a resist underlayer film can be prepared by mixing the compound [A], the solvent [B], and, if necessary, any optional components in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter or the like having a pore size of 0.5 μm or less.

[0117] [Coating Step] In this step, a composition for forming a resist underlayer film is applied directly or indirectly to a 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.

[0118] The method for applying the composition for forming a resist underlayer film is not particularly limited, and can be any appropriate method such as spin coating, cast coating, roll coating, etc. This forms a coating film, and the resist underlayer film is formed by volatilization of the solvent (B).

[0119] Examples of the substrate include metal or semimetal substrates such as silicon substrates, aluminum substrates, nickel substrates, chromium substrates, molybdenum substrates, tungsten substrates, copper substrates, tantalum substrates, and titanium substrates, among which silicon substrates are preferred.The substrate may also be a substrate on which a silicon nitride film, an alumina film, a silicon dioxide film, a tantalum nitride film, a titanium nitride film, or the like is formed.

[0120] The substrate may have a pattern. The resist underlayer film-forming composition has excellent embedding properties, so even when the substrate has a pattern, it can form a good film while filling the gaps between the patterns. Examples of the pattern shape include a trench pattern, a line-and-space pattern, a hole pattern, and a pillar pattern. Examples of trench patterns and line-and-space patterns include a pattern including a recess with a width of 5 nm to 100 nm, and a pattern including a recess with a depth of 5 nm to 500 nm. Examples of hole patterns include a pattern including a hole with a diameter of 5 nm to 100 nm, and a pattern including a hole with a depth of 5 nm to 500 nm. Examples of pillar patterns include a pattern including a pillar with a width of 5 nm to 100 nm, and a pattern including a pillar with a height of 5 nm to 500 nm.

[0121] 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 a low dielectric insulating film or an organic underlayer film formed on the substrate.

[0122] [Heating Step] In this step, the coating film formed in the coating step is heated. Heating the coating film promotes the formation of the resist underlayer film. More specifically, heating the coating film promotes the volatilization of the solvent (B), etc.

[0123] The coating film may be heated in an air atmosphere or a nitrogen atmosphere. The lower limit of the heating temperature is preferably 200°C, more preferably 240°C. The upper limit of the heating temperature is preferably 600°C, more preferably 500°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.

[0124] After the coating step, the resist underlayer film may be exposed to light. After the coating step, the resist underlayer film may be exposed to plasma. After the coating step, ions may be implanted into the resist underlayer film. Exposing the resist underlayer film to light improves the etching resistance of the resist underlayer film. Exposing the resist underlayer film to plasma improves the etching resistance of the resist underlayer film. Implanting ions into the resist underlayer film improves the etching resistance of the resist underlayer film.

[0125] The radiation used to expose the resist underlayer film is appropriately selected from electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays and gamma rays; and particle beams such as electron beams, molecular beams and ion beams.

[0126] The method of exposing the resist underlayer film to plasma includes, for example, a direct method in which the substrate is placed in a gas atmosphere and plasma discharge is performed. The conditions for plasma exposure are typically a gas flow rate of 50 cc / min to 100 cc / min and a supplied power of 100 W to 1,500 W.

[0127] The lower limit of the plasma exposure time is preferably 10 seconds, more preferably 30 seconds, and even more preferably 1 minute, and the upper limit of the plasma exposure time is preferably 10 minutes, more preferably 5 minutes, and even more preferably 2 minutes.

[0128] The plasma may be, for example, H ２ Plasma is generated in an atmosphere of a mixed gas of H gas and Ar gas. ２ In addition to gas and Ar gas, CF ４ Gas and CH ４ A carbon-containing gas such as H ２ CF 4 instead of either or both of the gas and Ar. ４ Gas, NF ３ Gas, CHF ３ Gas, CO ２ Gas, CH ２ F ２ Gas, CH ４ Gas and C ４ F ８ At least one of the gases may be introduced.

[0129] Ion implantation of the resist underlayer film implants dopants into the resist underlayer film. The dopants may be selected from the group consisting of boron, carbon, nitrogen, phosphorus, arsenic, aluminum, and tungsten. The implantation energy used to energize the dopants may range from about 0.5 keV to 60 keV, depending on the type of dopant used and the desired implant depth.

[0130] The lower limit of the average thickness of the resist underlayer film formed is preferably 30 nm, more preferably 50 nm, and even more preferably 100 nm. The upper limit of the average thickness is preferably 3,000 nm, more preferably 2,000 nm, and even more preferably 500 nm. The average thickness is measured by the method described in the Examples.

[0131] [Silicon-containing film forming process] In this process, a silicon-containing film is formed directly or indirectly on the resist underlayer film formed by the coating process or the heating process.When the silicon-containing film is formed indirectly on the resist underlayer film, for example, a surface-modified film of the resist underlayer film is formed on the resist underlayer film.The surface-modified film of the resist underlayer film is, for example, a film whose contact angle with water is different from that of the resist underlayer film.

[0132] The silicon-containing film can be formed by coating a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. Examples of methods for forming a silicon-containing film by coating a silicon-containing film-forming composition include a method in which the silicon-containing film-forming composition is directly or indirectly coated onto the resist underlayer film, and the resulting coating is then cured by exposure and / or heating. Examples of commercially available silicon-containing film-forming compositions include "NFC SOG01," "NFC SOG04," and "NFC SOG080" (all manufactured by JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxynitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0133] Examples of radiation used for the exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays and gamma rays, and particle beams such as electron beams, molecular beams and ion beams.

[0134] The lower limit of the temperature when heating the coating film is preferably 90° C., more preferably 150° C., and still more preferably 200° C. The upper limit of the temperature is preferably 550° C., more preferably 450° C., and still more preferably 300° C.

[0135] The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and even more preferably 20 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm. The average thickness of the silicon-containing film is a value measured using the spectroscopic ellipsometer, similar to the average thickness of the resist underlayer film.

[0136] [Resist pattern forming step] In this step, a resist pattern is formed directly or indirectly on the resist underlayer film.Methods for carrying out this step include, for example, a method using a resist composition, a method using a nanoimprint method, a method using a self-assembling composition, etc.As the case of indirectly forming a resist pattern on the resist underlayer film, for example, a case of forming a resist pattern on the silicon-containing film, etc.

[0137] 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.

[0138] The resist composition can be applied, for example, by rotary coating, etc. The pre-baking temperature and time can be adjusted appropriately depending on the type of resist composition used.

[0139] Next, the resist film formed as above is exposed by selective irradiation with radiation. The radiation used for exposure can be appropriately selected depending on the type of radiation-sensitive acid generator used in the resist composition, and examples thereof include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, electron beams, molecular beams, and particle beams such as 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 or the like, hereinafter also referred to as "EUV") is more preferred, and KrF excimer laser light, ArF excimer laser light or EUV is even more preferred.

[0140] After the exposure, post-baking can be carried out to improve resolution, pattern profile, developability, etc. The temperature and time of this post-baking can be appropriately determined depending on the type of resist composition used, etc.

[0141] Next, the exposed resist film is developed with a developer to form a resist pattern. This development may be alkaline development or organic solvent development. In the case of alkaline development, examples of the developer include basic aqueous solutions of ammonia, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc. These basic aqueous solutions may also contain an appropriate amount of a water-soluble organic solvent, such as an alcohol, e.g., methanol or ethanol, or a surfactant. In the case of organic solvent development, examples of the developer include the various organic solvents exemplified as the solvent [B] in the composition for forming a resist underlayer film described above.

[0142] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0143] [Etching Step] In this step, etching is performed using the resist pattern as a mask. The etching may be performed once or multiple times, i.e., sequentially using the pattern obtained by etching as a mask. From the viewpoint of obtaining a pattern with a better shape, multiple times is preferred. When performing multiple etchings, for example, etching is performed sequentially in the order of the silicon-containing film, the resist underlayer film, and the substrate. Examples of etching methods include dry etching and wet etching. From the viewpoint of obtaining a better pattern shape on the substrate, dry etching is preferred. For this dry etching, a gas plasma such as oxygen plasma is used. By the above etching, a semiconductor substrate having a predetermined pattern is obtained.

[0144] Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the mask pattern, the elemental composition of the film to be etched, etc., and can be, for example, CHF ３ , C.F. ４ , C ２ F ６ , C ３ F ８ , SF ６ Fluorine-based gases such as Cl ２ , BCl ３ Chlorine gases such as O ２ , O ３ , H ２ Oxygen-based gases such as O, H ２ , CO, CO ２ , C.H. ４ , C ２ H ２ , C ２ H ４ , C ２ H ６ , C ３ H ４ , C ３ H ６ , C ３ H ８ , HF, HI, HBr, HCl, NO, NH ３ , BCl ３ reducing gases such as He, N ２and inert gases such as Ar. These gases may be used in combination. When etching a substrate using the pattern of the resist underlayer film as a mask, a fluorine-based gas is usually used.

[0145] The composition for forming a resist underlayer film contains a compound [A] and a solvent [B]. As the composition for forming a resist underlayer film, the composition for forming a resist underlayer film used in the method for producing a semiconductor substrate can be suitably used.

[0146] <<Method for Producing Nitrogen-Containing Compound>> The method for producing the nitrogen-containing compound includes a step of reacting compound [a] with compound [b]. As the method for producing the nitrogen-containing compound, a method for producing compound [A] in the composition for forming a resist underlayer film used in the method for producing a semiconductor substrate can be suitably adopted.

[0147] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0148] [Weight-average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using GPC columns (two "G2000HXL" and one "G3000HXL" columns) manufactured by Tosoh Corporation under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C, with monodisperse polystyrene as the standard.

[0149] [Average Film Thickness] The average film thickness was determined by measuring the film thickness at 9 arbitrary positions at 5 cm intervals, including the center of the resist underlayer film formed on a silicon wafer (substrate), using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"), and calculating the average of these film thicknesses.

[0150] <Synthesis of Compound [A]> In the synthesis of Compound [A], the following compounds (a-1) to (a-9) were used as Compound [a], Compounds (b-1) to (b-16) were used as Compound [b], Compounds (c-1) to (c-3) were used as cyclized products, and Compounds (d-1) to (d-7) were used as aldehyde compounds, etc. The numbers attached to the repeating units indicate the molar ratio of the repeating units.

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] <Synthesis of Compound [A]> Compounds (A-1) to (A-10), (A-18) to (A-24), and (A-31) to (A-32) as compounds [A] represented by the following formulas, and polymers (A-11) to (A-17), (A-25) to (A-30), and (A-33) to (A-34), were synthesized according to the procedures shown below.

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165] Example 1-1 (Synthesis of Compound (A-1)) In a nitrogen atmosphere, 20.0 g of compound (a-1), 23.7 g of compound (b-1), 11.0 g of imidazole hydrochloride, and 100 g of N-methyl-2-pyrrolidone were added to a reaction vessel and reacted at 160°C for 15 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 400 g of methyl isobutyl ketone and 400 g of 1% aqueous oxalic acid were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 600 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (A-1). The Mw of compound (A-1) was 705.

[0166] [Examples 1-2 to 1-10] (Synthesis of Compounds (A-2) to (A-10)) Compounds (A-2) to (A-10) were obtained as products under the same reaction conditions as in Example 1-1, except that the types and amounts of raw material compounds shown in Table 1-1 were used.

[0167] [Examples 1-11 to 1-17] (Synthesis of polymers (A-11) to (A-17)) Polymers having repeating units represented by (A-11) to (A-17) were obtained as products under the same reaction conditions as in Example 1-1, except that the types and amounts of raw material compounds shown in Table 1-1 were used.

[0168] [Examples 1-18 to 1-24] (Synthesis of compounds (A-18) to (A-24)) Compounds (A-18) to (A-24) were obtained as products under the same reaction conditions as in Example 1-1, except that the types and amounts of raw material compounds shown in Table 1-1 were used.

[0169] Example 2-1 (Synthesis of Polymer (A-25)) In a nitrogen atmosphere, 10.9 g (30 mmol) of compound (c-1), 5.19 g (28.5 mmol) of compound (d-1), and 40 g of propylene glycol monomethyl ether acetate were placed in a reaction vessel and heated to 60°C. Next, 5.17 g (30 mmol) of p-toluenesulfonic acid monohydrate was dissolved in 20 g of propylene glycol monomethyl ether acetate and slowly added dropwise to the solution, followed by stirring at 120°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 200 g of methyl isobutyl ketone and 200 g of water were added to wash the organic phase. After separating the aqueous phase, the obtained organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 500 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The polymer was then dried in a vacuum dryer at 60°C for 12 hours to obtain a polymer having a repeating unit represented by (A-25). The Mw of the polymer having a repeating unit represented by (A-25) was 3,300.

[0170] Examples 2-2 to 2-4, 2-9 to 2-10 (Synthesis of polymers (A-26) to (A-28), (A-33), and (A-34)) Polymers having repeating units represented by (A-26) to (A-28), (A-33), and (A-34) were obtained as products under the same reaction conditions as in Example 2-1, except that 30 mmol of the [c] compound shown in Table 1-2 was used instead of 30 mmol of the compound (c-1) as a cyclized product, and 28.5 mmol of the [d] aldehyde compound shown in Table 1-2 was used instead of the aldehyde compound (d-1).

[0171] [Example 2-5] (Synthesis of polymer (A-29)) Polymer (A-29) was obtained as a product under the same reaction conditions as in Example 2-1, except that 14.3 mmol of each of two [d] aldehyde compounds shown in Table 1-2 was used instead of aldehyde compound (d-1).

[0172] Example 2-6 Synthesis of Polymer (A-30) A polymer having a repeating unit represented by (A-30) was obtained as a product under the same reaction conditions as in Example 2-1, except that 30 mmol of the [c] compound shown in Table 1-2 was used instead of 30 mmol of the compound (c-1) as a cyclized product, and 28.5 mmol of the [d] aldehyde compound shown in Table 1-2 was used instead of the aldehyde compound (d-1).

[0173] Example 2-7 (Synthesis of Compound (A-31)) In a nitrogen atmosphere, 18.1 g (50 mmol) of compound (c-1), 36.4 g (200 mmol) of compound (d-4), and 200 g of diethylene glycol dimethyl ether were placed in a reaction vessel and heated to 60°C. Next, 4.81 g of methanesulfonic acid was slowly added dropwise to the solution, followed by stirring at 130°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 400 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 500 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (A-31). The Mw of compound (A-31) was 1,019.

[0174] Example 2-8 Synthesis of Compound (A-32) Compound (A-32) was obtained as a product under the same reaction conditions as in Example 2-7, except that 50 mmol of compound (c-2) was used instead of 50 mmol of compound (c-1) and 100 mmol of compound (d-5) was used instead of 200 mmol of compound (d-5).

[0175] Comparative Synthesis Example 2-1 (Synthesis of Polymer (x-1)) 2-phenylbenzoxazole (30 mmol), 1-naphthol (30 mmol), and paraformaldehyde (1.8 g, 20 mmol) were placed in a reaction vessel under a nitrogen atmosphere. Next, p-toluenesulfonic acid monohydrate (0.57 g, 3 mmol) was dissolved in 100 g of propylene glycol monomethyl ether acetate, and the solution was then placed in a flask and stirred at 90°C. Samples were taken from the polymerization reaction product at 1-hour intervals, and the reaction was completed when the weight-average molecular weight reached approximately 2,000 to 4,000. After completion of the reaction, the reaction product was placed in 300 g of distilled water and 300 g of methanol, stirred, and allowed to stand. The supernatant was removed, and the precipitate was dissolved in 100 g of propylene glycol monomethyl ether acetate. The solution was then vigorously stirred in 300 g of methanol and 300 g of distilled water, and allowed to stand. The resulting supernatant was removed again, and the precipitate was collected by suction filtration and washed several times with 200 g of methanol. The precipitate was then dried in a vacuum dryer at 60° C. for 12 hours to obtain polymer (x-1) represented by the following formula. The Mw of polymer (x-1) was 2,630.

[0176]

[0177] Comparative Synthesis Example 2-2 (Synthesis of Polymer (x-2)) Polymer (x-2) was obtained in the same manner as in Comparative Synthesis Example 2-1, except that 30 mmol of 2-phenylbenzothiazole was used instead of 30 mmol of 2-phenylbenzoxazole. The Mw of polymer (x-2) was 3,650.

[0178]

[0179]

[0180]

[0181] <Preparation of composition for forming resist underlayer film> The compound [A], the solvent [B], the acid generator [C], the crosslinking agent [D] and other components used in the preparation of the composition for forming a resist underlayer film (hereinafter also referred to as the "composition") are shown below.

[0182] [[A] Compounds] A-1 to A-34: The compounds (A-1) to (A-10), (A-18) to (A-24), and (A-31) to (A-32) synthesized above, and polymers (A-11) to (A-17), (A-25) to (A-30), and (A-33) to (A-34).

[0183] [B] Solvent: B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0184] [[C] Acid Generator] C-1: A compound represented by the following formula (C-1):

[0185] [[D] Crosslinking Agent] D-1: A compound represented by the following formula (D-1): D-2: A compound represented by the following formula (D-2):

[0186] Other components x-1: Polymer (x-1) synthesized above x-2: Polymer (x-2) synthesized above

[0187] [Example 3-1] 3 parts by mass of (A-1) as the compound [A] was dissolved in 97 parts by mass of (B-1) as the solvent [B]. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare a composition (J-1).

[0188] Examples 3-2 to 3-36 and Comparative Examples 3-1 to 3-2 Compositions (J-2) to (J-26) and (CJ-1) to (CJ-2) were prepared in the same manner as in Example 3-1, 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.

[0189]

[0190] <Evaluation> [Examples 4-1 to 4-36 and Comparative Examples 4-1 to 4-2] Using the compositions for forming resist underlayer films prepared above, embedding ability and flatness were evaluated by the following methods. The evaluation results are also shown in Table 3 below.

[0191] [Filling Ability] The resist underlayer film-forming composition was applied by spin coating using a spin coater (Tokyo Electron Limited's "LITHIUS Pro Z") on a substrate on which a trench pattern with a depth of 65 nm and widths of 20 nm and 30 nm was formed. The spin coater rotation conditions were set so as to obtain a substrate with a film having an average thickness of 100 nm. The substrate was then heated at 400°C for 90 seconds in an air atmosphere, and then cooled at 23°C for 60 seconds. The cross-sectional shape of the substrate was observed (200,000 magnification) using a scanning electron microscope (Hitachi High-Technologies Corporation's "S-4800") to evaluate filling ability. The embedding ability was evaluated as "A" (good) when the resist underlayer film was embedded to the bottom of the 20 nm wide space pattern on the substrate, "B" (fairly good) when it was not embedded to the bottom of the 20 nm wide space pattern but was embedded to the bottom of the 30 nm wide space pattern, and "C" (poor) when it was not embedded to the bottom of the 30 nm wide space pattern.

[0192] [Flatness] The composition prepared above was applied by a spin coating method using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Ltd.) onto a silicon substrate 1 having a trench pattern of 150 nm deep and 10 μm wide formed thereon, as shown in Figure 1. Next, the substrate was heated at 250°C for 60 seconds in an air atmosphere and then cooled at 23°C for 60 seconds to form a resist underlayer film 2 having an average thickness of 200 nm in the non-trench pattern area, which was then heated at 350°C for 60 seconds in an air atmosphere and then cooled at 23°C for 60 seconds to obtain a silicon substrate with a resist underlayer film. The cross-sectional shape of the silicon substrate with the resist underlayer film was observed with a scanning electron microscope ("S-4800" manufactured by Hitachi High-Technologies Corporation), and the difference (ΔFT) between the height of the resist underlayer film 2 at the center portion b of the trench pattern and the height of the non-trench pattern portion a located 5 μm from the edge of the trench pattern was used as an index of flatness. Flatness was evaluated as "A" (good) when ΔFT was less than 20 nm, "B" (fairly good) when ΔFT was 20 nm or more but less than 30 nm, and "C" (poor) when ΔFT was 30 nm or more. The height difference shown in FIG. 1 is exaggerated compared to the actual height.

[0193]

[0194] As can be seen from the results in Table 3, the compositions of the examples and the resist underlayer films formed from the compositions were also superior in embedding ability and flatness compared to the comparative examples.

[0195] According to the method for producing a semiconductor substrate of the present invention, it is possible to form a resist underlayer film that not only has sufficient embedding ability to embed a substrate pattern but also has excellent flatness after embedding. According to the composition for forming a resist underlayer film of the present invention, it is possible to form a resist underlayer film that has excellent embedding ability and flatness. According to the method for producing a nitrogen-containing compound of the present invention, it is possible to efficiently produce a nitrogen-containing compound that is suitable as a component of the composition for forming a resist underlayer film for forming a resist underlayer film. Therefore, these compounds can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0196] 1 Silicon substrate 2 Resist underlayer film

Claims

1. A method for producing a semiconductor substrate, comprising: a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step; and a step of performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains a nitrogen-containing compound and a solvent, and the nitrogen-containing compound is a compound represented by the following formula (A1), (A2), or (A3), or a polymer having a repeating unit represented by the following formula (A4) or (A5). (In formulas (A1) to (A5), s is an integer of 1 to 4. When s is 2 or more, a plurality of R ａ , Ar and X are the same or different. ａ is a monovalent organic group having 1 to 40 carbon atoms. Each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. W １ When s is 1, 3, or 4, W is an s-valent organic group having 1 to 40 carbon atoms, and when s is 2, W is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent heteroatom-containing linking group. Each X is independently O, S, or NR'. R' is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. W ２ is a t-valent organic group having 1 to 40 carbon atoms. t is an integer of 1 to 4. When t is 2 or more, the plurality of Ar's and X's are the same or different from each other. R ｂ are each independently a monovalent organic group having 1 to 40 carbon atoms. ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. u1 and u2 are each independently an integer of 0 to 4, provided that u1+u2 is 2 or more. ｂ and X are the same or different from each other. ３１ is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent linking group containing a hetero atom. ３２ and W ４ are each independently a divalent organic group having 1 to 40 carbon atoms. ｃ is a monovalent organic group having 1 to 40 carbon atoms.

2. The method for producing a semiconductor substrate according to claim 1, further comprising the step of forming a silicon-containing film directly or indirectly on the resist underlayer film before forming the resist pattern.

3. A composition for forming a resist underlayer film, comprising: a nitrogen-containing compound; and a solvent, wherein the nitrogen-containing compound is a compound represented by the following formula (A1), (A2), or (A3), or a polymer having a repeating unit represented by the following formula (A4) or (A5). (In formulas (A1) to (A5), s is an integer of 1 to 4. When s is 2 or more, a plurality of R ａ , Ar and X are the same or different. ａ is a monovalent organic group having 1 to 40 carbon atoms. Each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. W １ When s is 1, 3, or 4, W is an s-valent organic group having 1 to 40 carbon atoms, and when s is 2, W is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent heteroatom-containing linking group. Each X is independently O, S, or NR'. R' is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. W ２ is a t-valent organic group having 1 to 40 carbon atoms. t is an integer of 1 to 4. When t is 2 or more, the plurality of Ar's and X's are the same or different from each other. R ｂ are each independently a monovalent organic group having 1 to 40 carbon atoms. ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. u1 and u2 are each independently an integer of 0 to 4, provided that u1+u2 is 2 or more. ｂ and X are the same or different from each other. ３１ is a divalent organic group having 1 to 40 carbon atoms, a single bond, or a divalent linking group containing a hetero atom. ３２ and W ４ are each independently a divalent organic group having 1 to 40 carbon atoms. ｃ is a monovalent organic group having 1 to 40 carbon atoms.

4. W １ is a substituted or unsubstituted s-valent hydrocarbon group having 1 to 40 carbon atoms, or a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group.

5. R ａ 4. The composition for forming a resist underlayer film according to claim 3, wherein is a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms.

6. W ２ is a substituted or unsubstituted, t-valent hydrocarbon group having 1 to 40 carbon atoms, or a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group.

7. R ｂ The composition for forming a resist underlayer film according to claim 3, wherein each of the groups independently represents a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms.

8. W ３１ , W ３２ and W ４ are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 40 carbon atoms or a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group.

9. R ｃ 4. The composition for forming a resist underlayer film according to claim 3, wherein is a monovalent group containing a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms.

10. The composition for forming a resist underlayer film according to claim 3, wherein the aromatic ring in Ar is a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring or a biphenyl ring.

11. The composition for forming a resist underlayer film according to claim 3, wherein X is O.

12. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound has a molecular weight of 500 or more.

13. A method for producing a nitrogen-containing compound, comprising a step of reacting a compound represented by the following formula (a1), (a2), or (a3) ​​with a compound represented by the following formula (b): (In formulas (a1) to (a3), each Ar is independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. Ar ｘ is a substituted or unsubstituted aromatic ring having 4 to 40 carbon atoms. １ is an s-valent organic group having 1 to 40 carbon atoms. Each X is independently O, S, or NH. s is an integer of 1 to 4. Each of u1 and u2 is independently an integer of 0 to 4, provided that u1+u2 is 2 or more. In formula (b), W ２ is a t-valent organic group having 1 to 40 carbon atoms. ｘ and R ｙ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, and t is an integer of 1 to 4.

14. The method for producing a nitrogen-containing compound according to claim 13, further comprising the step of reacting 1.5 to 2.5 moles of the compound represented by formula (a1) with 1 mole of a compound represented by formula (b) where t is 2 to produce a cyclized product, and then reacting the cyclized product with an aldehyde compound.

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