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 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 (i-1) or formula (i-2). (In formulae (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4-40 carbon atoms. Ra is a hydrogen atom or a monovalent organic group having 1-20 carbon atoms. Each * is a bond with another structure in the nitrogen-containing compound. n is an integer from 0 to 2.)

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, the method comprising: applying a composition for forming a resist underlayer film directly or indirectly to a substrate; forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step; and performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains a nitrogen-containing compound (hereinafter also referred to as "compound [A]") and a solvent (hereinafter also referred to as "solvent [B]"), and the nitrogen-containing compound contains a partial structure represented by the following formula (i-1) or formula (i-2) (hereinafter also referred to as "partial structure (i-1)" or the like, or, without distinguishing between the two, also referred to as "partial structure (i)" or the like). (In formulas (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound. n is an integer of 0 to 2.

[0008] According to this semiconductor substrate manufacturing method, by using a predetermined composition for forming a resist underlayer film in the coating step, a resist underlayer film with excellent filling ability and flatness can be formed, thereby enabling the production of a semiconductor substrate with a good pattern shape. While the reason for this is unclear, it is presumed as follows: Since the partial structure (i) contained in the compound [A] has a structurally flexible alicyclic structure, the solubility of the compound [A] as a whole is higher than that of aromatic imides. Meanwhile, since the partial structure (i) has a rigid structure compared to a chain structure such as maleimide, the heat resistance of the compound [A] as a whole is higher. Thus, it is presumed that the combined effect of solubility and heat resistance, properties that have traditionally been difficult to achieve together, enables the composition for forming a resist underlayer film to form a resist underlayer film with excellent filling ability and flatness.

[0009] In another embodiment, the present invention relates to a composition for forming a resist underlayer film, comprising: a nitrogen-containing compound; and a solvent, wherein the nitrogen-containing compound includes a partial structure represented by the following formula (i-1) or formula (i-2): (In formulas (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound. n is an integer of 0 to 2.

[0010] In yet another embodiment, the present invention relates to a method for producing a nitrogen-containing compound, comprising: reacting a compound represented by the following formula (a1) or (a2) (hereinafter also referred to as "compound [a]") with a compound represented by the following formula (b) (hereinafter also referred to as "compound [b]") to produce an amic acid compound: (In formulas (a1) and (a2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. In formula (b), R ｂ is a substituted or unsubstituted organic group having 1 to 40 carbon atoms and a valence of m, where m is an integer of 1 to 4.

[0011] As used herein, the term "fused ring" refers to a polycyclic structure formed by adjacent rings sharing one 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 Producing Semiconductor Substrate>> The method for producing a semiconductor substrate includes a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate (hereinafter also referred to as a "coating step"), a step of directly or indirectly forming a resist pattern 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 (i-1) or formula (i-2). The number of partial structures (i) in the compound [A] may be one or more. The composition for forming a resist underlayer film may contain one or more types of compound [A]. (In formulas (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. R ａis a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound. n is an integer of 0 to 2.

[0022] The alicyclic structure in Cy forms a fused ring with the five-membered imide ring in formula (i-1) above, or contains two carbon atoms in the amic acid structure in formula (i-2) above. The amic acid structure in formula (i-2) is dehydrated to obtain the imide ring in formula (i-1) above.

[0023] Examples of the alicyclic structure of Cy having 4 to 40 carbon atoms include a monocyclic or polycyclic aliphatic hydrocarbon structure having 4 to 40 carbon atoms, a structure in which some of the carbon atoms constituting the ring of the monocyclic or polycyclic aliphatic hydrocarbon structure having 4 to 40 carbon atoms are substituted with a divalent heteroatom-containing group, and a structure combining these. The combined form may be a fused ring structure, a ring assembly structure in which two adjacent rings are bonded by a single bond, or a spiro ring structure in which two adjacent rings share one carbon atom.

[0024] Examples of the monocyclic or polycyclic aliphatic hydrocarbon structure having 4 to 40 carbon atoms include a monocyclic or polycyclic cycloalkane structure, a monocyclic or polycyclic cycloalkene structure, and the like. Preferred examples of the monocyclic cycloalkane structure include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring. Preferred examples of the polycyclic cycloalkane structure include bridged ring structures such as a norbornane ring, an adamantane ring, a tricyclodecane ring, and a tetracyclododecane ring. Examples of the monocyclic cycloalkene structure include monocyclic cycloalkenyl groups such as a cyclopropene ring, a cyclobutene ring, a cyclopentene ring, and a cyclohexene ring. Examples of the polycyclic cycloalkene structure include a norbornene ring, a tricyclodecene ring, and a tetracyclododecene ring.

[0025] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -O-, -S-, and -SO ２ -, -NR'-, or a group formed by combining two or more of these. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0026] Cy may have a substituent. Examples of the substituent include a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a carboxy group, a hydroxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group. Examples of the alkyl group include a linear or branched alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. Examples of the fluorinated alkyl group include a linear or branched fluorinated alkyl group having 1 to 8 carbon atoms, such as a trifluoromethyl group or a pentafluoroethyl group. Examples of the alkoxy group include a linear or branched alkoxy group having 1 to 8 carbon atoms, such as a methoxy group, an ethoxy group, or a propoxy group. Examples of the alkoxycarbonyl group include a linear or alicyclic alkoxycarbonyl group having 2 to 16 carbon atoms, such as a methoxycarbonyl group, a butoxycarbonyl group, or an adamantylmethyloxycarbonyl group. Examples of alkoxycarbonyloxy groups include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethyloxycarbonyloxy. Examples of acyl groups include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, benzoyl, and acryloyl. Examples of acyloxy groups include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as acetyloxy, propionyloxy, benzoyloxy, and acryloyloxy.

[0027] The substituent of Cy may also be an aromatic ring structure fused with the alicyclic structure of Cy. Examples of the aromatic ring 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 heterocycles 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. 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, a coronene ring, and a biphenyl ring, more preferably a benzene ring, a naphthalene ring, a pyrene ring, a fluorene ring, a biphenyl ring, or a combination thereof, and even more preferably a benzene ring.

[0028] In terms of heat resistance, the alicyclic structure in Cy preferably contains at least one bridged structure selected from the group consisting of -O-, -S-, -CO- and an alkanediyl group having 1 to 10 carbon atoms.

[0029] The alicyclic structure in Cy preferably contains an unsaturated bond in terms of crosslinkability.

[0030] The alicyclic structure of Cy is preferably a cyclopentane structure, a cyclohexane structure, a cyclohexene structure, a norbornane structure, a norbornene structure, a bicyclo[2.2.2]octane structure, a bicyclo[2.2.2]oct-2-ene structure, a structure in which some of the carbon atoms constituting these ring structures are substituted with -O-, -S- or -CO-, or a structure formed by combining these structures.

[0031] R ａExamples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 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.

[0032] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and combinations thereof.

[0033] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0034] As the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a group in which one hydrogen atom has been removed from a structure in which the monocyclic or polycyclic aliphatic hydrocarbon structure having 4 to 40 carbon atoms shown in Cy above corresponds to a structure having 3 to 20 carbon atoms can be suitably used.

[0035] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0036] 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.

[0037] As the divalent heteroatom-containing group, the divalent heteroatom-containing groups shown above for Cy can be suitably employed.

[0038] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0039] R ａ R is preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms or an aralkyl group having 6 to 10 carbon atoms, and even more preferably a methyl group, an ethyl group, an n-propyl group, or a benzyl group. ａ As the substituent of , the above-mentioned substituents that Cy may have can be suitably adopted.

[0040] The compound [A] may be a low molecular weight compound containing the partial structure (i) (hereinafter also referred to as an "[A1] compound"), or may be a high molecular weight compound having two or more repeating units containing the partial structure (i) (hereinafter also referred to as an "[A2] polymer"). In this specification, a "low molecular weight compound" refers to a compound that has a relatively small molecular weight compared to a "high molecular weight compound" and does not have a repeating unit.

[0041] The other structure in the compound [A] other than the partial structure (i) 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 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.

[0042] In the other structures, the monovalent organic group having 1 to 40 carbon atoms includes R ａ A group in which the monovalent organic group having 1 to 20 carbon atoms shown in the above formula is extended to have 40 carbon atoms can be suitably used.

[0043] The other structure preferably contains an aromatic ring, and the aromatic rings shown as the substituents of Cy can be suitably used as the aromatic ring.

[0044] When the compound [A] is a polymer [A2], one repeating unit contains the partial structure (i) 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 (i) and a repeating unit not containing the partial structure (i).

[0045] The compound [A1] is preferably a compound represented by the following formula (A1-1), formula (A1-2), formula (A1-3) or formula (A1-4). (In formulas (A1-1) to (A1-4), R １２ａ , R １２ｂ , R ２２ａ and R ２２ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. １ is a g-valent organic group having 1 to 40 carbon atoms. ２ is an organic group having 1 to 40 carbon atoms and a valence of h. g and h are each independently an integer of 1 to 4. Cy and R ａ Cy and R have the same meanings as those in the formulae (i-1) and (i-2). ａ When there are a plurality of Cy and R ａ are the same or different.)

[0046] R １２ａ , R １２ｂ , R ２２ａ and R ２２ｂ 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 in other structures of the compound (A) can be suitably used.

[0047] X １ As the g-valent organic group having 1 to 40 carbon atoms represented by the formula (I), a group in which (g-1) hydrogen atoms have been removed from the monovalent organic group having 1 to 40 carbon atoms shown in the other structures of the compound [A] can be suitably used.

[0048] X ２ As the h-valent organic group having 1 to 40 carbon atoms represented by the formula (I), a group in which (h-1) hydrogen atoms have been removed from the monovalent organic group having 1 to 40 carbon atoms shown in the other structures of the compound [A] can be suitably used.

[0049] g and h each independently represent preferably an integer of 1 to 3, and more preferably 1 or 2.

[0050] Specific examples of the compound [A1] include, but are not limited to, those represented by the following formulae (A1-1-1) to (A1-1-12), (A1-2-1) to (A1-2-11), (A1-3-1) to (A1-3-2), and (A1-4-1) to (A1-4-2).

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058] The polymer [A2] preferably has a repeating unit represented by the following formula (A2-1), formula (A2-2), formula (A2-3), formula (A2-4) or formula (A2-5). (In formulas (A2-1) to (A2-5), Y １１ , Y １２ , Y １４ and Y １５ are each independently a divalent organic group having 1 to 40 carbon atoms. １３ is a single bond or a divalent organic group having 1 to 40 carbon atoms. ２３ is a monovalent organic group having 1 to 40 carbon atoms. Ar is a divalent group having an aromatic ring having 3 to 40 carbon atoms. Cy and R ａ Cy and R have the same meanings as those in the formulae (i-1) and (i-2). ａ When there are a plurality of Cy and R ａ are the same or different.)

[0059] Y １１ ~Y １５ and R ２３As the divalent organic group having 1 to 40 carbon atoms represented by the formula (I), 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 structures above can be suitably used.

[0060] As the aromatic ring having 3 to 40 carbon atoms in Ar, the aromatic rings shown in the other structures above can be suitably used.

[0061] Examples of repeating units that the polymer [A2] may have include repeating units represented by the following formulae (A2-1-1) to (A2-1-3), (A2-2-1) to (A2-2-2), (A2-3-1) to (A2-3-3), (A2-4-1) to (A2-4-2), and (A2-5-1) to (A2-5-2).

[0062]

[0063]

[0064]

[0065] The molecular weight of the [A] compound is preferably 500 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 540, and even more preferably 580. 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 2500, and even more preferably 3000. The upper limit of the molecular weight of the [A1] compound is preferably 10000, and even more preferably 8000. 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.

[0066] 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.

[0067] <Method for Producing Compound [A]> The method for producing compound [A] includes a step of reacting compound [a] with compound [b] to produce an amic acid compound. The production method may include a step of further reacting the produced amic acid compound.

[0068] (Amic Acid Compound Formation Step) In this production method, the compound [A] can be produced simply and efficiently by a ring-opening addition reaction between the compound [a] as an acid anhydride and the compound [b] as an amine. Since the compound [A] here is an amic acid compound, the partial structure (i-2) (R in the above formula (i-2)) ａ The resulting compound has a hydrogen atom.

[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), Cy represents a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms.)

[0070] As the alicyclic structure having 4 to 40 carbon atoms in Cy in the above formulas (a1) and (a2), the alicyclic structure having 4 to 40 carbon atoms in Cy in the above formula (i-1) can be suitably used. As the substituent in the case where Cy in the above formulas (a1) and (a2) has a substituent, the substituent which Cy in the above formula (i-1) can have can be suitably used.

[0071] The compound [a] also includes a polymerized form of the compound [a].

[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) to (a2-8).

[0075]

[0076] (Compound [b]) The compound [b] is a compound represented by the following formula (b). (In formula (b), R ｂ is a substituted or unsubstituted organic group having 1 to 40 carbon atoms and a valence of m, where m is an integer of 1 to 4.

[0077] R ｂ As the m-valent organic group having 1 to 40 carbon atoms represented by the formula (I), a group in which (m-1) hydrogen atoms have been removed from a monovalent organic group having 1 to 40 carbon atoms shown in the other structures of the compound [A] can be suitably used.

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

[0079] The compound [b] also includes a polymerized form of the compound [b].

[0080] Specific examples of the compound [b] include, but are not limited to, those represented by the following formulae (b-1) to (b-18).

[0081]

[0082]

[0083] The reaction of compound [a] with compound [b] can be carried out in a reaction solvent, preferably under an inert gas atmosphere such as a nitrogen gas atmosphere, according to a known method. Typically, compound [a] and compound [b] can be mixed and heated to react batchwise. The molar ratio of the reaction of compound [a], compound [b], and compound [c] depends on the number of acid anhydride structures in compound [a] and the number of NH in compound [b]. ２The reaction temperature can be set appropriately taking into consideration the number of groups. The lower limit of the reaction temperature is preferably 30°C, and more preferably 35°C. The upper limit of the reaction temperature is preferably 70°C, and more preferably 50°C. The lower limit of the reaction time is preferably 30 minutes, and more preferably 1 hour. The upper limit of the reaction time is preferably 8 hours, and more preferably 4 hours. After the reaction, the compound [A] (amic acid compound) can be obtained, if necessary, through separation, purification, drying, etc. As the reaction solvent, the solvent [B] described below can be suitably used.

[0084] (Dehydration cyclization reaction step) The production method may further include a step of carrying out a dehydration cyclization reaction of the amic acid compound. This forms an imide ring, and compound [A] having partial structure (i-1) can be obtained. When the dehydration cyclization reaction step is included, the reaction can be carried out in a solution containing the amic acid compound.

[0085] The dehydration cycloaddition reaction of the amic acid compound can be accelerated by heating, adding a dehydration cycloaddition promoter, or a combination of heating and adding a dehydration cycloaddition promoter. Amines can be used as the dehydration cycloaddition promoter, and a mixture of acetic anhydride and an amine can be preferably used. Examples of amines include aromatic amines such as pyridine, piperidine derivatives such as 1-methylpiperidine, and aliphatic amines such as trialkylamines. As the aliphatic amine, trialkylamines are more preferred, and triethylamine and diisopropylethylamine are even more preferred.

[0086] The lower limit of the reaction temperature is preferably 40°C, and more preferably 60°C. The upper limit of the reaction temperature is preferably 200°C, and more preferably 150°C. The lower limit of the reaction time is preferably 1 hour, and more preferably 2 hours. The upper limit of the reaction time is preferably 12 hours, and more preferably 10 hours. After the reaction, the compound [A] (imide ring-containing compound) can be obtained, if necessary, through separation, purification, drying, etc.

[0087] (Nucleophilic Reaction Step) The production method may further include a step of carrying out a nucleophilic reaction between the amic acid compound and a halogenated hydrocarbon, instead of the cyclodehydration reaction step. This step provides a protected compound (R ａ It is possible to produce a compound (A) having a partial structure (i-2) in which is a hydrocarbon group.

[0088] The hydrocarbon in the halogenated hydrocarbon is R ａ Suitable examples of the halogenated hydrocarbon include halogenated alkanes and aralkyl halides, and more preferred are iodomethane, 1-bromobutane, and benzyl bromide.

[0089] The lower limit of the reaction temperature is preferably 40°C, and more preferably 60°C. The upper limit of the reaction temperature is preferably 120°C, and more preferably 100°C. The lower limit of the reaction time is preferably 1 hour, and more preferably 2 hours. The upper limit of the reaction time is preferably 12 hours, and more preferably 6 hours. After the reaction, compound [A] (a protected form of the carboxy group of the amic acid compound) can be obtained, if necessary, through separation, purification, drying, etc.

[0090] <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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] [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.

[0101] [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.

[0102] [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.

[0103] 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).

[0104] 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.

[0105] 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.

[0106] 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.

[0107] [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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 ２CF 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.

[0114] 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.

[0115] 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.

[0116] [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.

[0117] 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).

[0118] 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.

[0119] 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.

[0120] 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.

[0121] [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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0128] [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.

[0129] 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 Cl２ , 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 ２ and 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.

[0130] 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.

[0131] <<Method for Producing Nitrogen-Containing Compound>> The method for producing the nitrogen-containing compound includes a step of reacting a compound represented by the following formula (a1) or (a2) with a compound represented by the following formula (b) to produce an amic acid compound. As the method for producing the nitrogen-containing compound, a method for producing the compound (A) in the composition for forming a resist underlayer film used in the method for producing a semiconductor substrate can be suitably used.

[0132] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0133] [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.

[0134] [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.

[0135] <Raw Material Compounds for Compound [A]> The following compounds (a-1) to (a-11) and the following compounds (b-1) to (b-15) were used in the synthesis of Compound [A].

[0136]

[0137]

[0138]

[0139] <Synthesis of [a-9]> Under a nitrogen atmosphere, 72 g of anhydrous toluene, 72 g of anhydrous ethyl acetate, 79.0 g of nadic anhydride, and 2.3 g of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were added to a vessel and heated to 80°C to obtain a feed monomer solution. Separately, 0.706 g of palladium(II) bis(dicyclohexylisopropylphosphine)diacetate was dissolved in 4 mL of anhydrous toluene and 4 mL of anhydrous ethyl acetate and poured into the reaction vessel. Concurrently with this pouring into the reaction vessel, the above-measured feed monomer solution was added at a rate that maintained a constant level of unreacted monomer throughout the polymerization reaction (36 hours). After the addition of the monomer was stopped, the polymerization reaction mixture was stirred for an additional hour and then cooled to room temperature. Ethyl acetate was added to the reaction solution, and the unreacted monomer was removed by liquid-liquid extraction. The gaseous phase was then concentrated, activated carbon was added, and the mixture was stirred for 1 hour, followed by filtration to remove residual palladium. The polymer solution was then precipitated in excess heptane, filtered, and dried in a vacuum oven to obtain compound [a-9], which had a Mw of 7,600.

[0140] <Synthesis of Compound [b-13]> 29.1 g of 2,7-dihydroxynaphthalene, 27.5 g of 4-nitrobenzaldehyde, and 185.0 g of 1-butanol were added to a reaction vessel under a nitrogen atmosphere and heated to 80°C to dissolve. A solution of 10.4 g of p-toluenesulfonic acid monohydrate in 1-butanol (15.0 g) was added to the reaction vessel, and the mixture was heated to 115°C and reacted for 15 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 200 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 concentrated, and the residue was added dropwise to 500 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The precipitate was then dissolved in 150 g of tetrahydrofuran, and 150 g of ethanol and 15.0 g of palladium carbon (5% palladium, aqueous) were added. The mixture was reacted at 60°C for 4 hours under a hydrogen gas atmosphere. After the reaction was completed, activated carbon was added to the reaction solution, which was stirred for 1 hour and then filtered to remove residual palladium. The resulting solution was concentrated, 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 200 g of heptane. The precipitate was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (b-13). The Mw of (b-13) was 4,650.

[0141] <Synthesis of Compound [A]> Compounds (A-1) to (A-27) were synthesized as Compound [A] according to the following procedure. In the formulas below, the values ​​attached to the repeating units are molar ratios.

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] Example 1-1 Synthesis of Compound (A-1) Under a nitrogen atmosphere, 20.0 g of compound (b-1) was added to 80 g of N-methyl-2-pyrrolidone in a reaction vessel to form a homogeneous solution at 40°C. Then, 16.0 g of compound (a-1) previously dissolved in 80 g of N-methyl-2-pyrrolidone was slowly added dropwise, and the reaction was carried out at an internal temperature of 40°C for 2 hours. Subsequently, 18.9 g of diisopropylethylamine was added to the resulting solution, and 14.9 g of acetic anhydride was slowly added dropwise thereto. The reaction was then carried out at 80°C for 4 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 400 g of 4-methyltetrahydropyran 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 200 g of a 7 / 3 (v / v) methanol / water solution to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 200 g of methanol. Then, it was dried in a vacuum dryer at 60° C. for 12 hours to obtain compound (A-1). Mw of (A-1) was 703.

[0150] [Examples 1-2 to 1-21, 1-25 to 1-27] (Synthesis of compounds (A-2) to (A-21), (A-25) to (A-27)) Compounds (A-2) to (A-21), (A-25) to (A-27) 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. Mw is also shown in Table 1. In the table, "-" indicates that the corresponding component was not used. The same applies to the subsequent tables.

[0151] [Example 1-22] (Synthesis of Compound (A-22)) In a nitrogen atmosphere, 20.0 g of compound (b-5) was added to 80 g of N-methyl-2-pyrrolidone in a reaction vessel to form a homogeneous solution at 40°C. Then, 12.3 g of compound (a-1) previously dissolved in 80 g of N-methyl-2-pyrrolidone was slowly added dropwise, and the reaction was carried out at an internal temperature of 40°C for 2 hours. Subsequently, 14.6 g of diisopropylethylamine was added to the resulting solution, and 16.0 g of iodomethane was slowly added dropwise. The reaction was carried out at 80°C for 4 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 400 g of 4-methyltetrahydropyran 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 200 g of a 7 / 3 (v / v) methanol / water solution to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 200 g of methanol. Then, it was dried in a vacuum dryer at 60° C. for 12 hours to obtain compound (A-22). Mw of (A-22) was 889.

[0152] Example 1-23 Synthesis of Compound (A-23) Compound (A-23) was obtained as a product under the same reaction conditions as in Example 1-22, except that 19.3 g of benzyl bromide was used instead of iodomethane.

[0153] [Example 1-24] (Synthesis of Compound (A-24)) In a nitrogen atmosphere, 20.0 g of compound (b-2) was added to 80 g of N-methyl-2-pyrrolidone in a reaction vessel to form a homogeneous solution at 40°C. Then, 9.57 g of compound (a-6) previously dissolved in 80 g of N-methyl-2-pyrrolidone was slowly added dropwise, and the reaction was carried out at an internal temperature of 40°C for 2 hours. Subsequently, 15.0 g of diisopropylethylamine was added to the resulting solution, and 15.9 g of 1-bromobutane was slowly added dropwise. The reaction was carried out at 80°C for 4 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 400 g of 4-methyltetrahydropyran 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 200 g of a 7 / 3 (v / v) methanol / water solution to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 200 g of methanol. Then, it was dried in a vacuum dryer at 60° C. for 12 hours to obtain compound (A-24). Mw of (A-24) was 4,600.

[0154] 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.

[0155]

[0156] Comparative Synthesis Example 1-2 (Synthesis of Compound (x-2)) 120 g of N-methyl-2-pyrrolidone was added to 4.54 g of 3,3'-diaminobenzidine and 20.66 g of 4-ethynylphthalic anhydride, and the mixture was allowed to react for 3 hours at an internal temperature of 40°C under a nitrogen atmosphere. 4.75 g of pyridine was added to the resulting solution, and 14.72 g of acetic anhydride was added dropwise, followed by a reaction at an internal temperature of 60°C for 4 hours. After completion of the reaction, the mixture was cooled to room temperature, and 300 g of methyl isobutyl ketone was added. The organic layer was washed with 100 g of a 3% aqueous nitric acid solution, and then washed five times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 100 g of tetrahydrofuran was added to the residue to form a homogeneous solution, which was then crystallized with 300 g of hexane. The precipitated crystals were separated by filtration, washed twice with 200 g of hexane, and then recovered. The recovered crystals were dried under vacuum at 70°C to obtain (x-2).

[0157]

[0158]

[0159] <Preparation of composition for forming resist underlayer film> [A] Compound, [B] solvent, [C] acid generator, [D] crosslinker and other components used in preparing a composition for forming a resist underlayer film (hereinafter also referred to as "composition") are shown below.

[0160] [[A] Compounds] A-1 to A-27: Compounds (A-1) to (A-27) 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: Polymer (x-1) synthesized above x-2: Polymer (x-2) 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 2-37 and Comparative Examples 2-1 to 2-2 Compositions (J-2) to (J-37) and (CJ-1) to (CJ-2) were prepared in the same manner as in Example 2-1, except that the types and amounts of each component shown in Table 2 below were used.

[0167]

[0168] <Evaluation> [Examples 3-1 to 3-37 and Comparative Examples 3-1 to 3-2] Using the compositions for forming resist underlayer films prepared above, embedding ability and flatness were evaluated by the following methods. The evaluation results are also shown in Table 3 below.

[0169] [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.

[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, 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.

[0174] 1 Silicon substrate 2 Resist underlayer film

Claims

1. A method for manufacturing 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 (i-1) or formula (i-2): (In formulas (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound. n is an integer of 0 to 2.

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 (i-1) or formula (i-2): (In formulas (i-1) and (i-2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bond to another structure in the nitrogen-containing compound. n is an integer of 0 to 2.

4. The composition for forming a resist underlayer film according to claim 3, wherein the alicyclic structure in Cy contains at least one bridged structure selected from the group consisting of -O-, -S-, -CO- and an alkanediyl group having 1 to 10 carbon atoms.

5. The composition for forming a resist underlayer film according to claim 3, wherein the alicyclic structure in Cy contains an unsaturated bond.

6. R ａ 4. The composition for forming a resist underlayer film according to claim 3, wherein is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.

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

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 (A1-1), (A1-2), (A1-3) or (A1-4): (In formulas (A1-1) to (A1-4), R １２ａ , R １２ｂ , R ２２ａ and R ２２ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. １ is a g-valent organic group having 1 to 40 carbon atoms. ２ is an organic group having 1 to 40 carbon atoms and a valence of h. g and h are each independently an integer of 1 to 4. Cy and R ａ Cy and R have the same meanings as those in the formulae (i-1) and (i-2). ａ When there are a plurality of Cy and R ａ are the same or different.) 9. The composition for forming a resist underlayer film according to claim 3, wherein the nitrogen-containing compound has a repeating unit represented by the following formula (A2-1), (A2-2), (A2-3), (A2-4) or (A2-5): (In formulas (A2-1) to (A2-5), Y １１ , Y １２ , Y １４ and Y １５ are each independently a divalent organic group having 1 to 40 carbon atoms. １３ is a single bond or a divalent organic group having 1 to 40 carbon atoms. ２３ is a monovalent organic group having 1 to 40 carbon atoms. Ar is a divalent group having an aromatic ring having 3 to 40 carbon atoms. Cy and R ａ Cy and R have the same meanings as those in the formulae (i-1) and (i-2). ａ When there are a plurality of Cy and R ａ 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.

11. A method for producing a nitrogen-containing compound, comprising the step of reacting a compound represented by the following formula (a1) or (a2) with a compound represented by the following formula (b) to produce an amic acid compound: (In formulas (a1) and (a2), Cy is a substituted or unsubstituted alicyclic structure having 4 to 40 carbon atoms. In formula (b), R ｂ is a substituted or unsubstituted organic group having 1 to 40 carbon atoms and a valence of m, where m is an integer of 1 to 4.

12. The method for producing a nitrogen-containing compound according to claim 11, further comprising a step of carrying out a dehydration cyclization reaction of the amic acid compound.

13. The method for producing a nitrogen-containing compound according to claim 11, further comprising the step of carrying out a nucleophilic reaction of said amide acid compound with a halogenated hydrocarbon.

Images