Semiconductor substrate production method and composition for forming resist underlayer film

Abstract

Provided are: a method for producing a semiconductor substrate using a composition capable of forming a film having excellent embedding properties and flatness; and a composition for forming a resist underlayer film. The method for producing a semiconductor substrate comprises: 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, and the nitrogen-containing compound comprises 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. Each ＊ is a bond with another structure in the nitrogen-containing compound.)

Description

Semiconductor substrate manufacturing method and composition for forming resist underlayer film

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

[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 that has excellent embedding properties and flatness, and a composition for forming a resist underlayer film.

[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. * 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 having excellent filling properties and flatness can be formed, and therefore a semiconductor substrate having a good pattern shape can be produced. Although the reason for this is unclear, it is presumed as follows. The partial structure (1) contained in the compound [A] has a quinoline-like structure, and contains a nitrogen atom derived from the quinoline-like structure, so that the polarity of the compound [A] as a whole is high (relatively basic). As a result, it is difficult to form a resist underlayer film, such as a SiON film or SiO film, which has a Si-OH structure (relatively acidic) on the surface. ２ The composition for forming a resist underlayer film interacts with a hydrophilic substrate on which a film or the like is provided, improving affinity. Furthermore, the composition has a robust aromatic ring structure, improving the heat resistance of the film and stabilizing it. 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. * represents a bond to another structure in the nitrogen-containing compound.

[0010] As used herein, "fused ring" refers to a polycyclic structure formed by adjacent rings sharing one edge (two adjacent atoms). "Ring assembly" refers to a polycyclic structure in which adjacent rings are bonded by a single bond. "Organic group" refers to a group containing at least one carbon atom. "Hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. "Chain hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not have to be composed only of an alicyclic structure and may contain a chain structure as part of it). The term "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure (however, it does not have to be composed solely of an aromatic ring structure, and may also contain an alicyclic structure or a chain structure as part of it).

[0011] 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. Therefore, these compositions can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0012] FIG. 10 is a schematic plan view for explaining a method for evaluating flatness.

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

[0014] <<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”).

[0015] 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.

[0016] 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").

[0017] The composition for forming a resist underlayer film used in the method for producing a semiconductor substrate and each step will be described below.

[0018] <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.

[0019] Hereinafter, each component contained in the composition for forming a resist underlayer film will be described.

[0020] <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. * represents a bond to another structure in the nitrogen-containing compound.

[0021] 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).

[0022] 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 any of a fused ring, a ring assembly, and 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.

[0023] 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.

[0024] Ar ２As 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.

[0025] 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.

[0026] Ar １ and Ar ２ It is preferable that at least one selected from the group consisting of has an OH group, which allows it to exhibit good affinity to the substrate.

[0027] 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.

[0028] 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.

[0029] Examples of the monovalent organic group having 1 to 40 carbon atoms in the other structures 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 end 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, or a combination thereof. The monovalent organic group having 1 to 40 carbon atoms also includes a cyano group and a carboxy group.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -NH-, -O-, -S-, and combinations of these groups.

[0036] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0037] The organic group as the other structure preferably contains an aromatic ring. １ The aromatic ring in the other structure may be bonded via the chain hydrocarbon group, the divalent heteroatom-containing group, or a group formed by combining these groups.

[0038] 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).

[0039] The compound [A] preferably contains at least two OH groups. When the compound [A] is a polymer [A2], it preferably contains at least two OH groups in one repeating unit. The number of OH groups is not particularly limited, and may be three, four, five, six, seven, eight, or nine or more, taking into consideration the properties of the resulting film, etc.

[0040] 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.

[0041] In the above formulas (A-1) and (A-2), R７ 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 shown in the other structures of the formula (1) above 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.

[0042] When the compound [A] has the group (α), the group (α) is at least Ar in the formula (1). １ , Ar ２ Alternatively, it is preferably bonded to an aromatic ring in the other structure.

[0043] 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 １１ｃ , R １１ｄ , R １２ａ , R １２ｂ , R １３ａ and R １３ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. X and Y are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ and Ar ２ In the above 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.)

[0044] R １１ａ , R １１ｂ , R １１ｃ , R １１ｄ , R １２ａ , R １２ｂ , R １３ａ and R １３ｂAs 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 shown in the other structures of the formula (1) above can be suitably used.

[0045] As the divalent organic group having 1 to 40 carbon atoms represented by X and Y, a group in which one hydrogen atom has been removed from the monovalent organic group having 1 to 40 carbon atoms shown in the other structure of the above formula (1) can be suitably used.

[0046] X is preferably a divalent aromatic ring group having 3 to 40 carbon atoms, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, a divalent heteroatom-containing group, or a group formed by combining these.

[0047] The divalent aromatic ring group having 3 to 40 carbon atoms represented by X is Ar in the above formula (1). １ A group in which two hydrogen atoms have been removed from an aromatic ring having 3 to 40 carbon atoms in the formula: can be suitably used. The aromatic ring in X is preferably a benzene ring, a biphenyl ring, or a 9,9-diphenylfluorene ring.

[0048] As the divalent chain hydrocarbon group having 1 to 10 carbon atoms for X, a group obtained by removing one hydrogen atom from the group corresponding to 1 to 10 carbon atoms among the monovalent chain hydrocarbon groups having 1 to 40 carbon atoms shown in the other structures above can be suitably used. As the divalent chain hydrocarbon group having 1 to 10 carbon atoms for X, a methylene group, an ethanediyl group, or a propanediyl group (propane-2,2-diyl group) is preferred.

[0049] The divalent heteroatom-containing group shown in the other structures above can be suitably used as the divalent heteroatom-containing group for X. The divalent heteroatom-containing group for X is preferably an ether bond (—O—).

[0050] Y is preferably a divalent hydrocarbon group having 6 to 20 carbon atoms, more preferably a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and even more preferably a benzenediyl 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 (A1-33).

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] The polymer [A2] preferably has 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 ２１ａ , R ２１ｂ , R ２２ａ and R ２２ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. ２２ｃ and R ２３ｃ are each independently a divalent organic group having 1 to 40 carbon atoms. X are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ and Ar ２ In the above 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.)

[0062] R ２１ａ , R ２１ｂ , R ２２ａ and R ２２ｂ 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 shown in the other structures of the formula (1) above can be suitably used.

[0063] In the above formulas (2-1) and (2-2), X in the above formula (1-1) can be suitably used as the divalent organic group having 1 to 40 carbon atoms represented by X.

[0064] 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 (A2-6).

[0065]

[0066]

[0067] 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 650, and even more preferably 700. The upper limit of the molecular weight of the [A1] compound is preferably 1500, and even more preferably 1200. 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 [A1] compound 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.

[0068] 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.

[0069] <Method for Producing Compound [A]> The method for producing compound [A] is not particularly limited as long as it can form partial structure (1) having a quinoline-like structure, and known methods can be used. This production method typically includes a step of reacting a carbon-carbon multiple bond-containing compound (hereinafter also referred to as "compound [a]"), a carbonyl group-containing aromatic compound (hereinafter also referred to as "compound [b]"), and an aniline structure-containing compound (hereinafter also referred to as "compound [c]") as raw material compounds. Compound [a] also includes compounds that generate a carbon-carbon double bond by keto-enol tautomerism. Known synthetic methods capable of forming partial structure (1) having the quinoline-like structure include the Povarov reaction, the Doebner reaction, and the Conrad-Limpach quinoline synthesis. An appropriate synthetic method can be adopted depending on the structure of the target compound [A]. In the Conrad-Limpach quinoline synthesis, the reaction can proceed without using compound [a].

[0070] (Compound [a]) The compound [a] is not particularly limited as long as it has a carbon-carbon multiple bond, i.e., a carbon-carbon double bond or a carbon-carbon triple bond. The compound [a] preferably has a vinyl group or an ethynyl group as the carbon-carbon multiple bond.

[0071] The number of carbon-carbon multiple bonds in the compound [a] is not particularly limited and may be set depending on the structure of the target compound [A]. The number of carbon-carbon multiple bonds is preferably 1, 2, or 3.

[0072] The compound [a] preferably contains an aromatic ring having 3 to 40 carbon atoms. The aromatic ring is Ar in the above formula (1). １ In the case where the aromatic ring in the compound [a] has a substituent, the substituent may be an aromatic ring having 3 to 40 carbon atoms, such as Ar in the above formula (1). １ The vinyl group or ethynyl group is preferably bonded to the aromatic ring.

[0073] When the compound [A] has an OH group, the compound [a] having an OH group may be used as a raw material compound and subjected to the reaction to introduce the OH group into the compound [A].

[0074] Specific examples of the compound [a] include, but are not limited to, compounds represented by the following formulas (a-1) to (a-14).

[0075]

[0076] (Compound [b]) The compound [b] is not particularly limited as long as it is a compound having a carbonyl group and an aromatic ring. The carbonyl group is preferably introduced as an aldehyde group or a ketone structure. The aldehyde group is preferably bonded to the aromatic ring. When the carbonyl group is introduced as a ketone structure, at least one of the structures bonded to the carbonyl group in the ketone structure is preferably the aromatic ring.

[0077] The number of aldehyde groups or ketone structures in the compound [b] is not particularly limited and may be set depending on the structure of the target compound [A]. The number of aldehyde groups or ketone structures is preferably 1, 2, or 3.

[0078] [b] The aromatic ring in the compound is Ar in the above formula (1). １ In the case where the aromatic ring in the compound [b] has a substituent, the substituent may be an aromatic ring having 3 to 40 carbon atoms, such as Ar in the above formula (1). １ The substituents that may be possessed by the group may be suitably employed.

[0079] When the compound [A] has an OH group, the compound [b] having an OH group may be used as a raw material compound and subjected to the reaction to introduce the OH group into the compound [A].

[0080] Specific examples of the compound [b] include, but are not limited to, compounds represented by the following formulas (b-1) to (b-15).

[0081]

[0082] (Compound [c]) The compound [c] is not particularly limited as long as it is a compound containing an aniline structure as a partial structure. The benzene ring in the aniline structure may form a condensed ring with another aromatic ring.

[0083] The number of aniline structures as partial structures in the compound [c] is not particularly limited and may be set depending on the structure of the target compound [A]. The number of the aniline structures is preferably 1, 2, or 3.

[0084] The compound [c] can suitably employ the other structures shown above in the compound [A] as a partial structure other than the aniline structure.

[0085] When the compound [A] has an OH group, the compound [c] having an OH group may be used as a raw material compound and subjected to the reaction to introduce the OH group into the compound [A].

[0086] Specific examples of the compound [c] include, but are not limited to, compounds represented by the following formulas (c-1) to (c-9).

[0087]

[0088] 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 are 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 [b] compound is reacted with the [c] compound, and then the [a] 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 carbon-carbon multiple bonds in the [a] compound, the number of carbonyl group-containing structures in the [b] compound, and the NH ２The 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, if necessary, the nitrogen-containing cyclic compound is aromatized with an oxidizing agent, and then the compound [A] can be obtained through separation, purification, drying, etc. As the reaction solvent, the solvent [B] described below can be suitably used.

[0089] <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.

[0090] 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.

[0091] 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.

[0092] Examples of ester-based solvents include carbonate-based solvents such as diethyl carbonate and propylene 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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 98% by mass.

[0099] [Optional Components] The composition for forming a resist underlayer film may contain optional components to the extent that the effects of the present invention are not impaired. Examples of optional components include an acid generator, a crosslinking agent, a surfactant, and an antifoaming agent. Known antifoaming agents can be used, such as alcohol antifoaming agents, phosphate ester antifoaming agents, fatty acid ester antifoaming agents, polyether antifoaming agents, and silicone antifoaming agents. Examples of fatty acid ester antifoaming 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 antifoaming agents. The optional components can 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 determined appropriately depending on the type of optional component, etc.

[0100] [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.

[0101] [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.

[0102] 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).

[0103] 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.

[0104] 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.

[0105] 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.

[0106] [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.

[0107] 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 230°C, and even more preferably 250°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 time is preferably 1,200 seconds, and more preferably 600 seconds. Heating may be performed stepwise from a low temperature to a high temperature within the heating temperature range.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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 time is preferably 10 minutes, more preferably 5 minutes, and even more preferably 2 minutes.

[0112] 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.

[0113] Ion implantation into 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 implant 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.

[0114] 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.

[0115] [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 a 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.

[0116] 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).

[0117] 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.

[0118] 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.

[0119] 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.

[0120] [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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0127] [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.

[0128] 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.

[0129] 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.

[0130] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0131] [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.

[0132] [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.

[0133] <Synthesis of Compound [A]> In the synthesis of Compound [A], compounds (a-1) to (a-13) represented by the following formulas (a-1) to (a-13) were used as Compound [a], compounds (b-1) to (b-14) represented by the following formulas (b-1) to (b-14) were used as Compound [b], and compounds (c-1) to (c-7) represented by the following formulas (c-1) to (c-7) were used as Compound [c].

[0134]

[0135]

[0136]

[0137] <Synthesis of Compound [A]> Compounds (A-1) to (A-33) as compounds [A] represented by the following formulae (A-1) to (A-33) were synthesized according to the procedure shown below.

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147] Example 1-1 (Synthesis of Compound (A-1)) In a nitrogen atmosphere, 20.0 g of compound (a-1), 17.7 g of compound (b-1), 34.2 g of compound (c-1), 10.0 g of boron trifluoride diethyl ether complex, and 200 g of tetrahydrofuran were added to a reaction vessel and reacted under reflux for 12 hours. Then, 40.0 g of 2,3-dichloro-5,6-dicyano-p-benzoquinone was added and reacted under reflux for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and the organic phase was washed with 800 g of methyl isobutyl ketone and 400 g of water. 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 800 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 819.

[0148] [Examples 1-2 to 1-25] (Synthesis of Compounds (A-2) to (A-25)) Compounds (A-2) to (A-25) 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 below were used. Mw is shown in Table 1.

[0149] Example 1-26 Synthesis of Compound (A-26) 20.0 g of compound (a-6), 13.3 g of compound (b-12), 22.3 g of compound (c-1), 55.1 g of iodine, and 300 g of dimethyl sulfoxide were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 120°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of dilute hydrochloric 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 800 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-26). The Mw of compound (A-26) was 1035.

[0150] [Example 1-27] (Synthesis of Compound (A-27)) Compound (A-27) was obtained as a product under the same reaction conditions as in Example 1-26, except that the types and amounts of raw material compounds shown in Table 1 below were used. Mw is shown in Table 1.

[0151] Example 1-28 Synthesis of Compound (A-28) In a nitrogen atmosphere, 20.0 g of compound (a-12), 21.0 g of compound (b-2), 35.3 g of compound (c-1), 10.0 g of boron trifluoride diethyl ether complex, and 200 g of tetrahydrofuran were added to a reaction vessel and reacted under reflux for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 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 800 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-28). The Mw of compound (A-28) was 847.

[0152] Example 1-29 Synthesis of Compound (A-29) 10.0 g of compound (a-13), 13.9 g of compound (b-2), 30.2 g of compound (c-5), and 200 g of diglyme were placed in a reaction vessel under a nitrogen atmosphere and reacted at 130°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 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 800 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-28). The Mw of compound (A-28) was 877.

[0153] Example 1-30 (Synthesis of Compound (A-30)) In a nitrogen atmosphere, 20.0 g of compound (b-14), 27.7 g of compound (c-5), 10.0 g of methanesulfonic acid, and 200 g of tetrahydrofuran were added to a reaction vessel and reacted under reflux for 12 hours. 23.6 g of 2,3-dichloro-5,6-dicyano-p-benzoquinone was then added and reacted under reflux for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 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 800 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-30). The Mw of compound (A-30) was 789.

[0154] Example 1-31 (Synthesis of Compound (A-31)) In a nitrogen atmosphere, 20.0 g of compound (a-1), 17.5 g of compound (b-10), 34.2 g of compound (c-1), 4.0 g of trifluoroacetic acid, and 200 g of 1,4-dioxane were added to a reaction vessel and reacted under reflux for 12 hours. Then, 40.0 g of 2,3-dichloro-5,6-dicyano-p-benzoquinone was added and reacted under reflux for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and the organic phase was washed with 800 g of methyl isobutyl ketone and 400 g of water. 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 800 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. Thereafter, the mixture was dried in a vacuum dryer at 60° C. for 12 hours to obtain compound (A-31). The Mw of compound (A-31) was 6,500.

[0155] [Examples 1-32 to 1-33] (Synthesis of compounds (A-32) to (A-33)) Compounds (A-32) to (A-33) were obtained as products under the same reaction conditions as in Example 1-31, except that the types and amounts of raw material compounds shown in Table 1 below were used. Mw is shown in Table 1.

[0156] 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.

[0157]

[0158]

[0159] <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.

[0160] [[A] Compounds] A-1 to A-33: Compounds (A-1) to (A-33) synthesized above

[0161] [B] Solvent: B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0162] [[C] Acid Generator] C-1: A compound represented by the following formula (C-1):

[0163] [[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):

[0164] Other components x-1: the polymer (x-1) synthesized above

[0165] [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).

[0166] Examples 2-2 to 2-43 and Comparative Example 2-1 Compositions (J-2) to (J-43) 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.

[0167]

[0168] <Evaluation> [Examples 3-1 to 3-43 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.

[0169] [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.

[0170] [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.

[0171]

[0172] 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.

[0173] According to the method for producing a semiconductor substrate of the present invention, a resist underlayer film is formed that not only has the ability to sufficiently fill a substrate pattern but also has excellent flatness after filling, so that a semiconductor substrate having a good pattern can be produced. The composition for forming a resist underlayer film of the present invention can form a resist underlayer film that is also excellent in both filling and flatness. Therefore, these compositions can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0174] 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. * 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. * 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 two OH groups.

5. Ar １ The composition for forming a resist underlayer film according to claim 3 , wherein is a benzene ring.

6. Ar ２ The composition for forming a resist underlayer film according to claim 3 , wherein 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 the nitrogen-containing compound has a molecular weight of 600 or more.

8. 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 １１ｃ , R １１ｄ , R １２ａ , R １２ｂ , R １３ａ and R １３ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. X and Y are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ and Ar ２ In the above 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.) 9. 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 ２１ａ , R ２１ｂ , R ２２ａ and R ２２ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. ２２ｃ and R ２３ｃ are each independently a divalent organic group having 1 to 40 carbon atoms. X are each independently a divalent organic group having 1 to 40 carbon atoms. Ar １ and Ar ２ In the above 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.) 10. 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.

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