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

Abstract

The present invention provides: a method for manufacturing a semiconductor substrate, in which a composition that is capable of forming a film having excellent embedding properties and excellent flatness is used; a composition for forming a resist underlayer film; and a method for producing a nitrogen-containing compound. This method for manufacturing a semiconductor substrate includes: a step for directly or indirectly coating a substrate with a composition for forming a resist underlayer film; a step for forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step; and a step for performing etching using the resist pattern as a mask. The composition for forming a resist underlayer film contains a nitrogen-containing compound and a solvent. The nitrogen-containing compound includes a partial structure that is represented by formula (1).　(In formula (1), Ar1 is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. Ar2 is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. Each * indicates an atomic bond with another structure in the nitrogen-containing compound.)

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 (WO 2011 / 108365).

[0004] International Publication No. 2011 / 108365

[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, 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 (hereinafter also referred to as “compound [A]”) and a solvent (hereinafter also referred to as “solvent [B]”), and the nitrogen-containing compound contains a partial structure represented by the following formula (1) (hereinafter also referred to as “partial structure (1)”). (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ２ is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound.

[0008] According to this method for producing a semiconductor substrate, by using a predetermined composition for forming a resist underlayer film in the coating step, a resist underlayer film with excellent embedding properties and flatness can be formed, and therefore a semiconductor substrate with a good pattern shape can be produced. Although the reason for this is not clear, it is presumed as follows. Since the partial structure (1) contained in the compound [A] has an NH group or a carbonyl group (CO group), the polarity of the compound [A] as a whole is high. As a result, it is difficult to form a SiON film or SiO 2 film on the surface in particular. ２ and the like. Furthermore, the NH group, carbonyl group, and tertiary amine structure of partial structure (1) each have a lone electron pair, which act as a coordinate with a metal atom (e.g., a silicon atom, a titanium atom, etc.) on the substrate surface or form a hydrogen bond with a hydroxy group of a metal oxide on the substrate surface, thereby improving the stability of compound [A] on the substrate surface. It is presumed that these combined effects enable the composition for forming a resist underlayer film to form a resist underlayer film that is excellent in embedding 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 contains a partial structure represented by the following formula (1): (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ２ is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound.

[0010] In yet another embodiment, the present invention relates to a method for producing a nitrogen-containing compound, comprising the step of reacting a compound represented by the following formula (a1) or (a2) (hereinafter also referred to as "compound [a]"), a compound represented by the following formula (b) (hereinafter also referred to as "compound [b]"), and a compound represented by the following formula (c) (hereinafter also referred to as "compound [c]"). (In formulas (a1) and (a2), Ar １ are each independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. １ are the same or different. Y is a divalent organic group having 1 to 40 carbon atoms. In formula (b), Ar ２ is a substituted or unsubstituted n alkyl group having 3 to 40 carbon atoms. １ It is an n-valent aromatic ring. １ is an integer of 1 to 4. In formula (c), R ２ is n having 1 to 40 carbon atoms ２ n is an n-valent organic group. ２ is an integer from 1 to 4.

[0011] As used herein, the term "fused ring" refers to a polycyclic structure formed by adjacent rings sharing one edge (two adjacent atoms). The term "organic group" refers to a group containing at least one carbon atom. The term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. The term "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a chain structure, including both linear hydrocarbon groups and branched hydrocarbon groups. The term "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, including both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not have to be composed solely of an alicyclic structure and may contain a chain structure as part of it). The term "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 solely of an aromatic ring structure and may contain an alicyclic structure or a chain structure as part of it).

[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] includes a partial structure represented by the following formula (1). The number of partial structures (1) in the compound [A] may be one or two or more. The composition for forming a resist underlayer film may contain one or two or more types of compound [A]. (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ２is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound.

[0022] Ar １ The aromatic ring represented by the formula (1) forms a condensed ring together with the nitrogen atom-containing 6-membered ring in the formula (1).

[0023] In the above formula (1), Ar １ Examples of the aromatic ring having 3 to 40 carbon atoms in Ar 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, and a coronene 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. １ 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, a perylene ring, and a coronene ring, more preferably a benzene ring, a naphthalene ring, or a pyrene ring, and even more preferably a benzene ring.

[0024] Ar １ may have a substituent. Examples of the substituent include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a hydroxy group (OH group), a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, an alkoxycarbonyl group such as a methoxycarbonyl group or an ethoxycarbonyl group, an alkoxycarbonyloxy group such as a methoxycarbonyloxy group or an ethoxycarbonyloxy group, an acyl group such as a formyl group, an acetyl group, a propionyl group, or a butyryl group, a cyano group, and a nitro group.

[0025] Ar ２ As the divalent aromatic ring having 3 to 40 carbon atoms in １ A group in which two hydrogen atoms have been removed from the aromatic ring having 3 to 40 carbon atoms shown in the above formula can be preferably used. ２ The aromatic ring in the formula (I) is preferably a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring or a biphenyl ring.

[0026] Ar ２ When Ar has a substituent, the substituent may be Ar １ The substituents that may be possessed by the group can be suitably employed.

[0027] The divalent organic group having 1 to 40 carbon atoms represented by X is a group in which one hydrogen atom has been removed from a monovalent organic group having 1 to 40 carbon atoms.

[0028] Examples of the monovalent organic group having 1 to 40 carbon atoms include a monovalent hydrocarbon group having 1 to 40 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the terminal of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing group, and combinations thereof.

[0029] Examples of the monovalent hydrocarbon group having 1 to 20 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, and combinations thereof.

[0030] 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 i-propyl group, an n-butyl group, a sec-butyl group, and a tert-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.

[0031] 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.

[0032] Examples of the monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms include Ar １ A group in which one hydrogen atom has been removed from the aromatic hydrocarbon ring shown as the aromatic ring in the above formula can be suitably used.

[0033] Examples of heteroatoms constituting the divalent or monovalent heteroatom-containing group 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.

[0034] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -NH-, -O-, -S-, and combinations of these groups.

[0035] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0036] X preferably contains a benzene ring, a naphthalene ring, a pyrene ring or a fluorene ring.

[0037] Ar １ , Ar ２ and X preferably has an OH group, and Ar ２ and X preferably has an OH group, thereby exhibiting good affinity to the substrate.

[0038] The compound [A] may be a low molecular weight compound containing the partial structure (1) (hereinafter also referred to as an "compound [A1]"), or may be a polymer having two or more repeating units containing the partial structure (1) (hereinafter also referred to as an "polymer [A2]"). In this specification, a "low molecular weight compound" refers to a compound that has a relatively small molecular weight compared to a "polymer" and does not have a repeating unit.

[0039] The other structure in the compound [A] other than the partial structure (1) is not particularly limited. An appropriate structure can be adopted depending on whether the compound [A] is the compound [A1] or the polymer [A2]. The other structure is preferably a hydrogen atom or a monovalent or divalent or higher organic group having 1 to 40 carbon atoms. The divalent or higher organic group having 1 to 40 carbon atoms is a group in which one or more hydrogen atoms have been removed from a monovalent organic group having 1 to 40 carbon atoms.

[0040] As the monovalent organic group having 1 to 40 carbon atoms in the other structures, the monovalent organic groups having 1 to 40 carbon atoms shown for X can be suitably used.

[0041] The other structure preferably contains an aromatic ring. １ An aromatic ring having 3 to 40 carbon atoms in the above formula can be preferably used.

[0042] When the compound [A] is a polymer [A2], one repeating unit contains the partial structure (1) and, as the other structure, a hydrogen atom or a monovalent or divalent or higher organic group having 1 to 40 carbon atoms. The polymer [A2] may have a repeating unit containing the partial structure (1) and a repeating unit not containing the partial structure (1).

[0043] The compound (A) preferably contains at least four groups selected from the group consisting of a carbonyl group, an NH group, and an OH group, more preferably contains at least two carbonyl groups and at least two NH groups, and even more preferably contains at least two carbonyl groups, at least two NH groups, and at least two OH groups.

[0044] The compound [A] may have, as a substituent, at least one group (hereinafter also referred to as "group (α)") selected from the group consisting of groups represented by the following formula (A-1) and groups represented by the following formula (A-2): This can improve the etching resistance and heat resistance of the resulting resist underlayer film. (In formulas (A-1) and (A-2), R ７ are each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. * is a bond to a carbon atom in the aromatic ring.

[0045] In the above formulas (A-1) and (A-2), R ７ As the divalent organic group having 1 to 20 carbon atoms represented by the formula (1), a group obtained by removing one hydrogen atom from a group corresponding to 1 to 20 carbon atoms among the monovalent organic groups having 1 to 40 carbon atoms represented by X in the formula (1) can be suitably used. ７ As the alkyl group, a divalent hydrocarbon group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, or a phenylene group, or a combination of these with -O-, is preferred, and a methanediyl group or a combination of a methanediyl group and -O- is more preferred.

[0046] The group (α) is Ar in the formula (1). １ , Ar ２ and preferably bonded to the aromatic ring constituting X or to the aromatic ring in the other structure.

[0047] The compound [A1] is preferably a compound represented by the following formula (1-1), (1-2) or (1-3). (In formulas (1-1), (1-2) and (1-3), R １１ａ , R １１ｂ , R １２ａ , R １２ｂ , R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. Y is a divalent organic group having 1 to 40 carbon atoms. Ar １ , Ar ２ and X have the same meaning as in the formula (1). In the formulas (1-1), (1-2) and (1-3), a plurality of Ar１ In the above formulas (1-1) and (1-3), a plurality of Ar ２ are the same or different. In the above formulas (1-2) and (1-3), multiple Xs are the same or different.

[0048] R １１ａ , R １１ｂ , R １２ａ , R １２ｂ , R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ As the monovalent organic group having 1 to 40 carbon atoms represented by the formula (1), the monovalent organic group having 1 to 40 carbon atoms represented by X in the formula (1) above can be suitably used.

[0049] As the divalent organic group having 1 to 40 carbon atoms represented by Y, a group in which one hydrogen atom has been removed from the monovalent organic group having 1 to 40 carbon atoms represented by X in the above formula (1) can be suitably used.

[0050] Y is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent chain hydrocarbon group having 1 to 12 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and even more preferably a methylene group or a biphenyl-4,4'-diyl group.

[0051] Specific examples of the compound [A1] include, but are not limited to, the following formulae (A1-1) to (A1-37).

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] The compound [A2] may be a polymer having a repeating unit represented by the following formula (2-1), (2-2), or (2-3). (In formulas (2-1), (2-2) and (2-3), R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. Y are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ , Ar ２ and X have the same meaning as in the formula (1). In the formulas (2-1), (2-2) and (2-3), a plurality of Ar １ In the above formula (2-2), a plurality of Ar ２ are the same or different from each other. In the above formula (2-3), multiple Xs are the same or different from each other.

[0061] R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ As the monovalent organic group having 1 to 40 carbon atoms represented by the formula (I), the monovalent organic groups having 1 to 40 carbon atoms shown above as other structures can be suitably used.

[0062] In the above formulas (2-2) and (2-3), as the divalent organic group having 1 to 40 carbon atoms represented by Y, Y in the above formula (1-3) can be suitably used.

[0063] Examples of the repeating units represented by the above formulae (2-1), (2-2) and (2-3) include repeating units represented by the following formulae (A2-1) to (A2-9).

[0064]

[0065]

[0066] The molecular weight of the [A] compound is preferably 600 or more, regardless of whether the [A] compound is an [A1] compound or an [A2] polymer. When the [A] compound is an [A1] compound, the lower limit of the molecular weight of the [A1] compound is more preferably 700, and even more preferably 800. The upper limit of the molecular weight of the [A1] compound is preferably 1800, and even more preferably 1500. When the [A] compound is an [A2] polymer, the lower limit of the molecular weight of the [A2] polymer is more preferably 2000, and even more preferably 2500. The upper limit of the molecular weight of the [A2] polymer is preferably 8000, and even more preferably 7000. The molecular weight of the [A1] compound is a value calculated from the structural formula. The molecular weight of the [A2] polymer is a weight average molecular weight measured by gel permeation chromatography using monodisperse polystyrene as a standard.

[0067] 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.

[0068] <Method for Producing Compound [A]> The method for producing compound [A] includes a step of reacting compound [a], compound [b], and compound [c]. In this production method, compound [A] can be produced simply and efficiently by a three-component condensation reaction of compound [a] as an isatoic anhydride, compound [b] as an aldehyde, and compound [c] as an amine.

[0069] (Compound [a]) The compound [a] is a compound represented by the following formula (a1) or (a2) (hereinafter, also referred to as "compound [a1]"). (In formulas (a1) and (a2), Ar １are each independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. １ are the same or different. Y is a divalent organic group having 1 to 40 carbon atoms.

[0070] Ar in the above formulas (a1) and (a2) １ As the aromatic ring having 3 to 40 carbon atoms in the above formula (1), Ar １ Ar in the above formula (a1) and (a2) can be suitably used. １ When Ar has a substituent, the substituent may be Ar in the above formula (1). １ The substituents that may be possessed by the group may be suitably employed.

[0071] In the above formula (a2), as the divalent organic group having 1 to 40 carbon atoms represented by Y, Y in the above formula (1-3) can be suitably used.

[0072] Specific examples of the compound [a1] include, but are not limited to, the following formulae (a1-1) to (a1-9).

[0073]

[0074] Specific examples of the compound [a2] include, but are not limited to, the following formulae (a2-1) and (a2-2).

[0075]

[0076] (Compound [b]) The compound [b] is a compound represented by the following formula (b). (In formula (b), Ar ２ is a substituted or unsubstituted n alkyl group having 3 to 40 carbon atoms. １ It is an n-valent aromatic ring. １ is an integer from 1 to 4.

[0077] Ar in the above formula (b) ２ n having 3 to 40 carbon atoms １ As the aromatic ring, Ar in the above formula (1) １ From the aromatic ring having 3 to 40 carbon atoms in １ An aromatic ring in which one hydrogen atom has been removed can be preferably used.２ When Ar has a substituent, the substituent may be Ar in the above formula (1). １ The substituents that may be possessed by the group may be suitably employed.

[0078] n １ is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0079] Specific examples of the compound [b] include, but are not limited to, those represented by the following formulae (b-1) to (b-16).

[0080]

[0081] (Compound [c]) The compound [c] is a compound represented by the following formula (c). (In formula (c), R ２ is n having 1 to 40 carbon atoms ２ n is an n-valent organic group. ２ is an integer from 1 to 4.

[0082] R ２ n having 1 to 40 carbon atoms represented by ２ The monovalent organic group may be selected from the group consisting of monovalent organic groups having 1 to 40 carbon atoms represented by X in the above formula (1) and (n ２ -1) A group in which one hydrogen atom has been removed can be preferably used.

[0083] n ２ is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0084] Specific examples of the compound [c] include, but are not limited to, the following formulae (c-1) to (c-14).

[0085]

[0086] The reaction of the [a] compound, the [b] compound, and the [c] compound 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, the [a] compound, the [b] compound, and the [c] compound can be mixed and heated to carry out a batch reaction. Depending on the reactivity of the raw materials, a sequential reaction may be carried out in which the [a] compound is reacted with the [c] compound, and then the [b] compound is reacted. The molar ratio of the reaction of the [a] compound, the [b] compound, and the [c] compound depends on the number of -CO-O-CO-NH- structures in the [a] compound, the number of CHO groups in the [b] compound, and the number of NH groups in the [c] compound. ２ The reaction temperature can be set appropriately taking into consideration the number of groups. 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 200°C, more preferably 160°C, and more preferably 140°C. The reaction temperature may be set at 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. In the case of a sequential reaction, the reaction temperature and reaction time may be set within the above-mentioned reaction temperature and reaction time ranges for each stage. An acid catalyst may be added during the reaction. The acid catalyst is not particularly limited, and known inorganic acids and organic acids can be used. After the reaction, compound [A] can be obtained through separation, purification, drying, etc. As the reaction solvent, the solvent [B] described below can be suitably used.

[0087] <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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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-methylpyrrolidone.

[0095] The solvent (B) is preferably an ester solvent or a ketone solvent, more preferably a polyhydric alcohol partial ether carboxylate solvent or a cyclic ketone solvent, and even more preferably propylene glycol monomethyl ether acetate or cyclohexanone.

[0096] 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.

[0097] [Optional Components] The composition for forming a resist underlayer film may contain optional components within a range that does not impair the effects of the present invention. Examples of optional components include an acid generator, a crosslinking agent, a surfactant, and the like. The optional components may be used alone or in combination of two or more. The content ratio 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.

[0098] [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.

[0099] [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.

[0100] 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).

[0101] 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.

[0102] 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.

[0103] 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.

[0104] [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.

[0105] The coating film may be heated in an air atmosphere or a nitrogen atmosphere. The lower limit of the heating temperature is preferably 300°C, more preferably 320°C, and even more preferably 340°C. The upper limit of the heating temperature is preferably 600°C, and more preferably 500°C. The lower limit of the heating time is preferably 15 seconds, and more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, and more preferably 600 seconds.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] [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.

[0114] 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).

[0115] 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.

[0116] 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.

[0117] 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.

[0118] [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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0125] [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.

[0126] 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.

[0127] 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.

[0128] <<Method for Producing Nitrogen-Containing Compound>> The method for producing the nitrogen-containing compound includes a step of reacting compound [a], compound [b], and compound [c]. 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.

[0129] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0130] [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.

[0131] [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.

[0132] <Synthesis of Compound [A]> In the synthesis of Compound [A], compounds (a-1) to (a-8) represented by the following formulas (a-1) to (a-8) were used as Compound [a], compounds (b-1) to (b-15) represented by the following formulas (b-1) to (b-15) were used as Compound [b], and compounds (c-1) to (c-11) represented by the following formulas (c-1) to (c-11) were used as Compound [c].

[0133]

[0134]

[0135]

[0136] <Synthesis of Compound [A]> Compounds (A-1) to (A-36) represented by the following formulas were synthesized as Compound [A] according to the procedure shown below.

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] Example 1-1 Synthesis of Compound (A-1) 20.0 g of compound (a-1), 13.0 g of compound (b-1), 25.2 g of compound (c-1), 100 g of glacial acetic acid, and 100 g of dioxane were added to a reaction vessel under a nitrogen atmosphere (molar ratio of compound (a-1), compound (b-1), and compound (c-1) of 2:2:1), and the mixture was allowed to react under reflux 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 400 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 the compound (A-1) was 825.

[0146] [Examples 1-2 to 1-11, 1-13 to 1-19, 1-21 to 1-23, 1-27 to 1-35] (Synthesis of compounds (A-2) to (A-11), (A-13) to (A-19), (A-21) to (A-23), and (A-27) to (A-35)) Compounds (A-2) to (A-11), (A-13) to (A-19), (A-21) to (A-23), and (A-27) to (A-35) 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 were used. The Mw of the obtained compounds is also shown in Table 1.

[0147] Example 1-12 (Synthesis of Compound (A-12)) 20.0 g of compound (a-1), 28.3 g of compound (b-12), 25.2 g of compound (c-1), 10.0 g of p-toluenesulfonic acid monohydrate, and 100 g of dimethylformamide were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react 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 400 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-12). The Mw of (A-12) was 1073.

[0148] [Examples 1-20, 1-24 to 1-26, 1-36] (Synthesis of compounds (A-20), (A-24) to (A-26), and (A-36)) Compounds (A-20), (A-24) to (A-26), and (A-36) were obtained as products under the same reaction conditions as in Example 1-12, except that the types and amounts of raw material compounds shown in Table 1 were used. The Mw of the obtained compounds is also shown in Table 1.

[0149] Comparative Synthesis Example 1-1 Synthesis of Polymer (x-1) 250.0 g of m-cresol, 125.0 g of 37% by mass formalin, and 2 g of anhydrous oxalic acid were added to a reaction vessel under a nitrogen atmosphere, and the mixture was reacted at 100° C. for 3 hours and at 180° C. for 1 hour. After that, unreacted monomers were removed under reduced pressure to obtain Polymer (x-1) represented by the following formula (x-1). The Mw of the obtained Polymer (x-1) was 11,000.

[0150]

[0151]

[0152] <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.

[0153] [[A] Compounds] A-1 to A-36: Compounds (A-1) to (A-36) synthesized above

[0154] [B] Solvent: B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0155] [[C] Acid Generator] C-1: A compound represented by the following formula (C-1):

[0156] [[D] Crosslinking Agent] D-1: A compound represented by the following formula (D-1):

[0157] D-2: A compound represented by the following formula (D-2):

[0158] Other components x-1: the polymer (x-1) synthesized above

[0159] [Example 2-1] 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).

[0160] Examples 2-2 to 2-49 and Comparative Example 2-1 Compositions (J-2) to (J-49) and (CJ-1) were prepared in the same manner as in Example 2-1, 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.

[0161]

[0162] <Evaluation> [Examples 3-1 to 3-49 and Comparative Example 3-1] 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.

[0163] [Filling Ability] The resist underlayer film-forming composition was applied by spin coating using a spin coater ("LITHIUS Pro Z" manufactured by Tokyo Electron Limited) onto a substrate on which a trench pattern with a depth of 65 nm and widths of 20 nm and 25 nm had been formed. The spin coater was rotated under conditions such that a substrate with a film having an average thickness of 100 nm was obtained. 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 ("S-4800" manufactured by Hitachi High-Technologies Corporation) 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 25 nm wide space pattern, and "C" (poor) when it was not embedded to the bottom of the 25 nm wide space pattern.

[0164] [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.

[0165]

[0166] 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.

[0167] 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.

[0168] 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 contains a partial structure represented by the following formula (1): (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ２ is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound.

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 contains a partial structure represented by the following formula (1): (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. ２ is a substituted or unsubstituted divalent aromatic ring having 3 to 40 carbon atoms. X is a divalent organic group having 1 to 40 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound.

4. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound contains at least four groups selected from the group consisting of a carbonyl group, an NH group, and an OH group.

5. Ar １ , Ar ２ and X has an OH group.

6. Ar ２ 4. The composition for forming a resist underlayer film according to claim 3, wherein the aromatic ring in the formula (I) is a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, or a biphenyl ring.

7. The composition for forming a resist underlayer film according to claim 3, wherein X contains a benzene ring, a naphthalene ring, a pyrene ring, or a fluorene ring.

8. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound has a molecular weight of 600 or more.

9. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound is a compound represented by the following formula (1-1), (1-2) or (1-3): (In formulas (1-1), (1-2) and (1-3), R １１ａ , R １１ｂ , R １２ａ , R １２ｂ , R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. Y is a divalent organic group having 1 to 40 carbon atoms. Ar １ , Ar ２ and X have the same meaning as in the formula (1). In the formulas (1-1), (1-2) and (1-3), a plurality of Ar １ In the above formulas (1-1) and (1-3), a plurality of Ar ２ are the same or different. In the above formulas (1-2) and (1-3), multiple Xs are the same or different.

10. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound is a polymer having a repeating unit represented by the following formula (2-1), (2-2) or (2-3): (In formulas (2-1), (2-2) and (2-3), R １３ａ , R １３ｂ , R １３ｃ and R １３ｄ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. Y are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ , Ar ２ and X have the same meaning as in the formula (1). In the formulas (2-1), (2-2) and (2-3), a plurality of Ar １ In the above formula (2-2), a plurality of Ar ２ are the same or different from each other. In the above formula (2-3), multiple Xs are the same or different from each other.

11. A composition for forming a resist underlayer film according to claim 3, wherein the content of the nitrogen-containing compound in the components other than the solvent in the composition for forming a resist underlayer film is 1 mass % or more.

12. A method for producing a nitrogen-containing compound, comprising the step of reacting a compound represented by the following formula (a1) or (a2), a compound represented by the following formula (b), and a compound represented by the following formula (c): (In formulas (a1) and (a2), Ar １ are each independently a substituted or unsubstituted aromatic ring having 3 to 40 carbon atoms. １ are the same or different. Y is a divalent organic group having 1 to 40 carbon atoms. In formula (b), Ar ２ is a substituted or unsubstituted n alkyl group having 3 to 40 carbon atoms. １ It is an n-valent aromatic ring. １ is an integer of 1 to 4. In formula (c), R ２ is n having 1 to 40 carbon atoms ２ n is an n-valent organic group. ２ is an integer from 1 to 4.

13. A method for producing a nitrogen-containing compound according to claim 12, comprising reacting a compound represented by formula (a1) or (a2) with a compound represented by formula (c) and then reacting the compound represented by formula (b).

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