Semiconductor substrate manufacturing method, composition, polymer, and polymer manufacturing method

Abstract

The purpose of the present invention is to provide: a method for manufacturing a semiconductor substrate using a composition from which a film having excellent etching resistance, heat resistance, and bending resistance can be formed; a composition; a polymer; and a method for producing a polymer. This method for manufacturing a semiconductor substrate comprises: a step for applying a resist underlayer film-forming composition directly or indirectly to a substrate; a step for forming resist patterns directly or indirectly on the resist underlayer film formed in the application step; and a step for performing etching using the resist patterns as masks, wherein the resist underlayer film-forming composition contains a solvent and a polymer having a repeating unit represented by formula (1). (In formula (1), Ar1 is a divalent group having an aromatic ring with 5-40 membered rings. R0 is a group represented by formula (1-1) or (1-2).) (In formula (1-1) or (1-2), X1 and X2 are each independently a group represented by formula (i), (ii), (iii), or (iv). * is a dangling bond to the carbon atom in formula (1). Ar2, Ar3, and Ar4 are each independently a substituted or unsubstituted aromatic ring with 6-20 membered rings, which forms a condensed ring structure together with adjacent two carbon atoms in formulae (1-1) and (1-2).) (In formula (i), R1 and R2 are each independently a hydrogen atom or a C1-C20 monovalent organic group.　In formula (ii), R3 is a hydrogen atom or a C1-C20 monovalent organic group. R4 is a C1-C20 monovalent organic group.　In formula (iii), R5 is a C1-C20 monovalent organic group.　In formula (iv), R6 is a hydrogen atom or a C1-C20 monovalent organic group.)

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a semiconductor substrate, a composition, a polymer, and a method for manufacturing a polymer. [Background technology]

[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 (see JP 2004-177668 A).

[0003] Various studies have been conducted on materials used in such compositions for forming resist underlayer films (see International Publication No. 2011 / 108365). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-177668 [Patent Document 2] International Publication No. 2011 / 108365 Summary of the Invention [Problem to be solved by the invention]

[0005] In a multilayer resist process, the organic underlayer film serving as the resist underlayer film is required to have etching resistance, heat resistance, and bending resistance.

[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 etching resistance, heat resistance, and bending resistance, a composition, a polymer, and a method for producing a polymer. [Means for solving the problem]

[0007] In one embodiment, the present invention provides a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step; a step of performing etching using the resist pattern as a mask; Including, The composition for forming a resist underlayer film, A polymer having a repeating unit represented by the following formula (1) (hereinafter also referred to as "polymer [A]"), solvent (hereinafter also referred to as "[B] solvent") The present invention relates to a method for manufacturing a semiconductor substrate, comprising the steps of: [ka] (In formula (1), Ar 1 is a divalent group having an aromatic ring with 5 to 40 ring members. 0 is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2 are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (1). Ar 2 , Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

[0008] In this specification, "number of ring members" refers to the number of atoms constituting a ring. For example, a biphenyl ring has 12 ring members, a naphthalene ring has 10 ring members, and a fluorene ring has 13 ring members. A "fused ring structure" refers to a structure in which adjacent rings share one edge (two adjacent atoms). An "organic group" refers to a group containing at least one carbon atom.

[0009] In another embodiment, the present invention provides A polymer having a repeating unit represented by the following formula (1): Solvent and The present invention relates to a composition comprising: [ka] (In formula (1), Ar 1 is a divalent group having an aromatic ring with 5 to 40 ring members. 0 is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (1). Ar 2 , Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

[0010] In yet another embodiment, the present invention provides The present invention relates to a polymer having a repeating unit represented by the following formula (1): [ka] (In formula (1), Ar 1 is a divalent group having an aromatic ring with 5 to 40 ring members. 0 is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2 are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (1). Ar 2, Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

[0011] In one embodiment, the present invention provides A step of reacting a compound having an aromatic ring with 5 to 40 ring members (hereinafter also referred to as "compound [a]") with a compound represented by the following formula (4-1), (4-2), (4-3) or (4-4) (hereinafter also referred to as "compound [b]"). The present invention relates to a method for producing a polymer comprising the steps of: [ka] (In formula (4-1), R 0a is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2 are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (4-1). Ar 2 , Ar 3 and Ar4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. [ka] (In formula (4-2), R 0a is the same as in formula (4-1) above. x1 and R x2 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. [ka] (In formula (4-3), R 0a is the same as in formula (4-1) above. x3 is a divalent hydrocarbon group having 1 to 10 carbon atoms. [ka] (In formula (4-4), R 0a´ is R in the above formula (4-1). 0a It is a divalent organic group with one less hydrogen atom than R x4 is a monovalent hydrocarbon group having 1 to 10 carbon atoms. [Effects of the Invention]

[0012] According to the method for producing a semiconductor substrate, a resist underlayer film having excellent etching resistance, heat resistance, and bending resistance is formed, thereby enabling the production of a good semiconductor substrate. According to the composition, a film having excellent etching resistance, heat resistance, and bending resistance can be formed. The polymer can be suitably used as a component of a composition for forming a resist underlayer film. The method for producing a polymer can efficiently produce a polymer suitable as a component of a composition for forming a resist underlayer film. Therefore, these can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a schematic plan view for explaining a method for evaluating bending resistance. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, the method for manufacturing a semiconductor substrate, the composition, the polymer, and the method for manufacturing a polymer according to each embodiment of the present invention will be described in detail.

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

[0016] According to the method for producing a semiconductor substrate, by using the composition described below as a composition for forming a resist underlayer film in the coating step, a resist underlayer film having excellent etching resistance, heat resistance, and bending resistance can be formed, and therefore a semiconductor substrate having a good pattern shape can be produced.

[0017] The method for manufacturing a semiconductor substrate may further include, if necessary, a step of heating the resist underlayer film formed in the coating step at 300°C or higher (hereinafter also referred to as a "heating step") before the resist pattern forming step.

[0018] 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 formed by the coating step or the heating step (hereinafter also referred to as a "silicon-containing film forming step").

[0019] The composition used in the method for producing a semiconductor substrate and each step will be described below.

[0020] <Composition> The composition as a composition for forming a resist underlayer film contains a polymer [A] and a solvent [B]. The composition may contain optional components as long as the effects of the present invention are not impaired.

[0021] The composition contains the polymer [A] and the solvent [B], and thus can form a film having excellent etching resistance, heat resistance, and bending resistance. Therefore, the composition can be used as a composition for forming a film. More specifically, the composition can be suitably used as a composition for forming a resist underlayer film in a multilayer resist process.

[0022] Each component contained in the composition will be described below.

[0023] <[A] Polymer> The polymer [A] has a repeating unit represented by the following formula (1): The composition may contain one or more types of polymer [A]. [ka] (In formula (1), Ar 1 is a divalent group having an aromatic ring with 5 to 40 ring members. 0is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2 are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (1). Ar 2 , Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

[0024] In the above formula (1), Ar 1 Examples of the aromatic ring having 5 to 40 ring members in the above Ar include aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, phenalene ring, phenanthrene ring, pyrene ring, fluorene ring, perylene ring, and coronene ring, and aromatic heterocycles such as furan ring, pyrrole ring, thiophene ring, phosphole ring, pyrazole ring, oxazole ring, isoxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, and triazine ring, and combinations thereof. 1The 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, and more preferably a benzene ring, a naphthalene ring, or a pyrene ring.

[0025] In the above formula (1), Ar 1 As the divalent group having an aromatic ring with 5 to 40 ring members represented by the formula: 1 Suitable examples include groups in which two hydrogen atoms have been removed from an aromatic ring having 5 to 40 ring members.

[0026] In the above formulas (i), (ii), (iii) and (iv), R 1 , R 2 , R 3 , R 4 , R 5 and R 6 Examples 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 carbon chain terminal, 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.

[0027] 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.

[0028] In this specification, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a linear structure, and includes 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, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not have to be composed only of an alicyclic structure and may contain a linear structure as part of it). 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 only of an aromatic ring structure and may contain an alicyclic structure or a linear structure as part of it).

[0029] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0030] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 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.

[0031] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group.

[0032] 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.

[0033] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -NH-, -O-, -S-, and combinations of these groups.

[0034] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0035] In the above formulas (1-1) and (1-2), Ar 2 , Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). 2 , Ar 3 and Ar 4 The aromatic ring having 6 to 20 ring members in the above formula (1) is Ar 1 Among the aromatic rings having 5 to 40 ring members in the above, aromatic rings having 6 to 20 ring members are preferred.

[0036] Ar 2 , Ar 3 and Ar 4 may have a substituent. Examples of the substituent include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, 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.

[0037] The above Ar 1has preferably at least one group selected from the group consisting of a hydroxy group, a group represented by the following formula (2-1), and a group represented by the following formula (2-2) as a substituent, which can improve the etching resistance and heat resistance of the resulting resist underlayer film. [ka] (In formulas (2-1) and (2-2), 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.

[0038] In the above formulas (2-1) and (2-2), R 7 The divalent organic group having 1 to 20 carbon atoms represented by the formula (i), (ii), (iii), and (iv) includes R 1 , R 2 , R 3 , R 4 , R 5 and R 6 Examples of such a group include a group in which one hydrogen atom has been removed from a monovalent organic group in the above formula. 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 thereof with -O-, is preferred, and a methanediyl group or a combination of a methanediyl group and -O- is more preferred.

[0039] Examples of the repeating unit represented by the above formula (1) include repeating units represented by the following formulae (1-1) to (1-32).

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] Among these, the repeating units represented by the above formulae (1-1) to (1-11) and (1-25) to (1-32) are preferred.

[0047] The polymer [A] may further have a repeating unit represented by the following formula (3). [ka] (In formula (3), Ar 5 is a divalent group having an aromatic ring with 5 to 40 ring members. 1 is a hydrogen atom or a monovalent organic group having 1 to 60 carbon atoms (provided that R 0 Excluding groups that fall under the following.

[0048] Ar 5 The aromatic ring having 5 to 40 ring members in the above formula (1) is Ar 1 An aromatic ring having 5 to 40 ring members in the above formula can be suitably used.

[0049] Ar 5 As the divalent group having an aromatic ring with 5 to 40 ring members represented by the formula: 5 Suitable examples include groups in which two hydrogen atoms have been removed from an aromatic ring having 5 to 40 ring members.

[0050] R 1The monovalent organic group having 1 to 60 carbon atoms represented by the formula (1) is R 0 Examples of such groups include monovalent hydrocarbon groups having 1 to 60 carbon atoms, groups having a divalent heteroatom-containing group between the carbon atoms of the hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with monovalent heteroatom-containing groups, and combinations thereof. These groups include the groups represented by R 1 , R 2 , R 3 , R 4 , R 5 and R 6 The groups exemplified as constituent groups of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula (I) can be suitably used, and the groups having up to 60 carbon atoms can be used.

[0051] Examples of the repeating unit represented by the above formula (3) include repeating units represented by the following formulas (3-1) to (3-8).

[0052] [ka]

[0053] The lower limit of the weight-average molecular weight of the polymer [A] is preferably 500, more preferably 1000, even more preferably 1500, and particularly preferably 2000. The upper limit of the molecular weight is preferably 10000, more preferably 8000, even more preferably 6000, and particularly preferably 5000. The method for measuring the weight-average molecular weight is as described in the Examples.

[0054] The upper limit of the content of hydrogen atoms relative to all atoms constituting the polymer [A] is preferably 5.5% by mass, more preferably 5.2% by mass, even more preferably 5.0% by mass, and particularly preferably 4.8% by mass. The lower limit of the content is, for example, 0.1% by mass. By setting the content of hydrogen atoms relative to all atoms constituting the polymer [A] within the above range, the bending resistance of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved. The content of hydrogen atoms relative to all atoms constituting the polymer [A] is a value calculated from the molecular formula of the polymer [A].

[0055] The lower limit of the content of the polymer [A] in the composition is preferably 2% by mass, more preferably 4% by mass, even more preferably 5% by mass, and particularly preferably 6% by mass, based on the total mass of the polymer [A] and the solvent [B]. The upper limit of the content is preferably 30% by mass, more preferably 25% by mass, even more preferably 20% by mass, and particularly preferably 18% by mass, based on the total mass of the polymer [A] and the solvent [B].

[0056] <[A] Method for producing polymer> The method for producing the polymer [A] includes a step of reacting the compound [a] with the compound [b]. 1 and the compound [a] as a precursor to give R 0 The novolak-type polymer [A] can be produced simply and efficiently by acid addition condensation of a precursor aldehyde or an aldehyde derivative with a compound [b] to give the polymer [A].

[0057] ([a] compound) The compound [a] has an aromatic ring having 5 to 40 ring members. The aromatic ring having 5 to 40 ring members is Ar in the above formula (1). 1 The compound [a] may preferably have an aromatic ring having 5 to 40 ring members as a substituent. 1 It is preferable that the aryl group has the group shown as a substituent in the formula:

[0058] ([b] compound) The [b] compound is represented by the following formula (4-1), (4-2), (4-3) or (4-4) (hereinafter, the compounds represented by formulas (4-1), (4-2), (4-3) and (4-4) are also referred to as the "[b1] compound", the "[b2] compound", the "[b3] compound" and the "[b4] compound", respectively). [ka] (In formula (4-1), R 0a is a group represented by the following formula (1-1) or (1-2): [ka] (In formulas (1-1) and (1-2), X 1 and X 2 are each independently a group represented by the following formula (i), (ii), (iii) or (iv). * is a bond to the carbon atom in the above formula (4-1). Ar 2 , Ar 3 and Ar 4 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formulas (1-1) and (1-2). [ka] (In formula (i), R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. 4 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iii), R 5 is a monovalent organic group having 1 to 20 carbon atoms. In formula (iv), R 6 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. [ka] (In formula (4-2), R 0ais the same as in formula (4-1) above. x1 and R x2 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. [ka] (In formula (4-3), R 0a is the same as in formula (4-1) above. x3 is a divalent hydrocarbon group having 1 to 10 carbon atoms. [ka] (In formula (4-4), R 0a´ is R in the above formula (4-1). 0a It is a divalent organic group with one less hydrogen atom than R x4 is a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0059] [b1] In the compound, R 0a As the R in the above formula (1), 0 The groups shown below can be preferably employed.

[0060] [b2] In the compound, R x1 and R x2 The monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (i), (ii), (iii), and (iv) above includes R 1 , R 2 , R 3 , R 4 , R 5 and R 6 Among monovalent hydrocarbon groups having 1 to 20 carbon atoms, those having 1 to 10 carbon atoms, represented by the following formula, can be suitably used.

[0061] [b3] In the compound, R x3 As the divalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula [b2], R x1 and R x2 Suitable examples include groups in which one hydrogen atom has been removed from a monovalent hydrocarbon group having 1 to 10 carbon atoms, represented by the following formula:

[0062] [b4] In the compound, R 0a´ As the R in the above formula (1), 0 A divalent group having one less hydrogen atom than the group shown as R can be suitably used. x4 As the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula [b2], R x1 and R x2 A monovalent hydrocarbon group having 1 to 10 carbon atoms and represented by the following formula can be suitably used.

[0063] The addition condensation of compound [a] and compound [b] can be carried out according to known methods, preferably under an inert gas atmosphere such as a nitrogen gas atmosphere. The lower limit of the reaction temperature for the addition condensation is preferably 50°C, preferably 70°C, and more preferably 80°C. The upper limit of the reaction temperature is preferably 200°C, preferably 160°C, and more preferably 150°C. The lower limit of the reaction time is preferably 1 hour, preferably 2 hours, and more preferably 5 hours. The upper limit of the reaction time is preferably 36 hours, preferably 24 hours, and more preferably 20 hours. The acid catalyst is not particularly limited, and known inorganic acids and organic acids can be used. After the addition condensation, polymer [A] can be obtained through separation, purification, drying, etc. The solvent [B] described below can be suitably used as the reaction solvent.

[0064] Furthermore, for example, modification of the fluorene moiety can be carried out by Knoevenagel condensation of the fluorene moiety with an aldehyde containing the desired structure under basic conditions.

[0065] <[B] Solvent> The solvent (B) is not particularly limited as long as it can dissolve or disperse the polymer (A) and any optional components contained as needed.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, and n-propanol, and polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0070] 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.

[0071] Examples of ether solvents include chain ether solvents such as n-butyl ether, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether.

[0072] Examples of the nitrogen-containing solvent include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0073] The solvent (B) is preferably an ester solvent or a ketone solvent, more preferably a polyhydric alcohol partial ether carboxylate solvent or a cyclic ketone solvent, and even more preferably propylene glycol monomethyl ether acetate or cyclohexanone.

[0074] The lower limit of the content of the solvent [B] in the composition is preferably 50% by mass, more preferably 60% by mass, and even more preferably 70% by mass, and the upper limit of the content is preferably 99.9% by mass, more preferably 99% by mass, and even more preferably 95% by mass.

[0075] [Optional ingredients] The composition may contain optional components within the range that does not impair the effects of the present invention. Examples of optional components include an acid generator, a crosslinking agent, a surfactant, etc. The optional components may be used alone or in combination of two or more. The content ratio of the optional components in the composition may be appropriately determined depending on the type of optional component, etc.

[0076] [Method for preparing the composition] The composition can be prepared by mixing the polymer [A], the solvent [B], and, if necessary, any optional components in a predetermined ratio, and then filtering the resulting mixture preferably through a membrane filter or the like having a pore size of 0.5 μm or less.

[0077] [Coating process] In this step, the 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 is the composition described above.

[0078] 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, casting coating, roll coating, etc. This forms a coating film, and the resist underlayer film is formed by volatilization of the solvent [B].

[0079] 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.

[0080] An example of the case where the composition for forming a resist underlayer film is indirectly applied to a substrate is the case where the composition for forming a resist underlayer film is applied onto a silicon-containing film, which will be described later, formed on the substrate.

[0081] [Heating process] 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 evaporation of the solvent [B].

[0082] 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 350°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.

[0083] 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.

[0084] 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.

[0085] The resist underlayer film can be exposed to plasma, for example, by a direct method in which the substrate is placed in a gas atmosphere and plasma discharge is performed. The plasma exposure conditions are typically a gas flow rate of 50 cc / min to 100 cc / min and a power supply of 100 W to 1,500 W.

[0086] 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 is preferably 10 minutes, more preferably 5 minutes, and even more preferably 2 minutes.

[0087] The plasma is generated in an atmosphere of a mixed gas of, for example, H2 gas and Ar gas. Furthermore, in addition to H2 gas and Ar gas, a carbon-containing gas such as CF4 gas or CH4 gas may be introduced. Instead of either or both of H2 gas and Ar gas, at least one of CF4 gas, NF3 gas, CHF3 gas, CO2 gas, CH2F2 gas, CH4 gas, and C4F8 gas may be introduced.

[0088] 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 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.

[0089] 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 as described in the Examples.

[0090] [Silicon-containing film formation 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.

[0091] 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 coated film is then cured by exposure and / or heating. Examples of commercially available silicon-containing film-forming compositions that can be used 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).

[0092] 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.

[0093] The lower limit of the temperature when heating the coating film is preferably 90°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the temperature is preferably 550°C, more preferably 450°C, and even more preferably 300°C.

[0094] 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.

[0095] [Resist pattern formation process] 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.An example of a case where a resist pattern is formed indirectly on the resist underlayer film is, for example, a case where a resist pattern is formed on the silicon-containing film.

[0096] Examples of the resist composition include a positive or negative chemically amplified resist composition that contains a radiation-sensitive acid generator, a positive resist composition that contains an alkali-soluble resin and a quinone diazide-based photosensitizer, and a negative resist composition that contains an alkali-soluble resin and a crosslinking agent.

[0097] 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.

[0098] Next, the resist film formed 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 include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, and particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, and KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F2 excimer laser light (wavelength 157 nm), Kr2 excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., hereinafter also referred to as "EUV") is more preferred, and KrF excimer laser light, ArF excimer laser light, or EUV is even more preferred.

[0099] 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.

[0100] 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 aqueous basic solutions of ammonia, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc. These aqueous basic 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 above as the solvent [B] of the composition.

[0101] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0102] [Etching process] 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.

[0103] 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 examples thereof include fluorine-based gases such as CHF3, CF4, C2F6, C3F8, and SF6; chlorine-based gases such as Cl2 and BCl3; oxygen-based gases such as O2, O3, and H2O; reducing gases such as H2, NH3, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HF, HI, HBr, HCl, NO, NH3, and BCl3; and inert gases such as He, N2, and Ar. These gases can also be used in combination. When etching a substrate using a resist underlayer film pattern as a mask, a fluorine-based gas is usually used.

[0104] 《Composition》 The composition contains a polymer [A] and a solvent [B]. As the composition, the composition used in the method for producing a semiconductor substrate can be suitably used.

[0105] Polymer The polymer has a repeating unit represented by the above formula (1). As the polymer, the polymer [A] in the composition used in the above method for producing a semiconductor substrate can be suitably used.

[0106] <<Method for producing polymer>> The method for producing the polymer includes a step of reacting compound [a] with compound [b]. As the method for producing the polymer, the method for producing polymer [A] in the composition used in the method for producing a semiconductor substrate can be suitably adopted. [Example]

[0107] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0108] [Weight average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using Tosoh GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C, with monodisperse polystyrene as the standard.

[0109] [Average thickness of resist underlayer film] The average thickness of the resist underlayer film was determined by measuring the film thickness at nine arbitrary positions at 5 cm intervals, including the center of the resist underlayer film, using a spectroscopic ellipsometer (JAWOOLLAM's "M2000D"), and calculating the average of these film thicknesses.

[0110] <Synthesis of Polymer [A]> Polymers having repeating units represented by the following formulae (A-1) to (A-24) and (x-1) to (x-2) (hereinafter also referred to as "polymer (A-1)") were synthesized by the following procedure.

[0111] [Example 1-1] (Synthesis of Polymer (A-1)) A reaction vessel was charged with 20.0 g of 1-hydroxypyrene, 19.8 g of 2-fluorenecarboxaldehyde, and 90.0 g of 1-butanol under a nitrogen atmosphere and heated to 80°C to dissolve the components. A solution of 4.3 g of p-toluenesulfonic acid monohydrate in 10.0 g of 1-butanol was added to the reaction vessel, which was then 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 using an evaporator, 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-1) represented by the following formula (A-1). The Mw of polymer (A-1) was 2,300.

[0112] [ka]

[0113] [Example 1-2] (Synthesis of Polymer (A-2)) A reaction vessel was charged with 5.0 g of polymer (A-1), 25.0 g of methyl isobutyl ketone, 12.5 g of methanol, and 6.2 g of tetramethylammonium hydroxide (25% aqueous solution). The mixture was stirred at room temperature under a nitrogen atmosphere for several minutes to dissolve polymer (A-1). 2.0 g of propargyl bromide was added, and the mixture was heated from room temperature to 50°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-2) represented by the following formula (A-2). The Mw of polymer (A-2) was 2,700.

[0114] [ka]

[0115] [Example 1-3] (Synthesis of Polymer (A-3)) 5.0 g of polymer (A-1), 40.0 g of cyclopentyl methyl ether, 1.2 g of tetramethylammonium bromide, and 8.8 g of 50% aqueous NaOH solution were added to a reaction vessel and stirred under a nitrogen atmosphere at room temperature for several minutes to dissolve polymer (A-1). 6.6 g of propargyl bromide was added, and the mixture was heated from room temperature to 90°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-3) represented by the following formula (A-3). The Mw of polymer (A-3) was 3,100.

[0116] [ka]

[0117] [Example 1-4] (Synthesis of Polymer (A-4)) Polymer (A-4) corresponding to the following formula (A-4) was obtained by carrying out the reaction under the same conditions as in [Example 1-3], except that 4.4 g of propargyl bromide and 5.4 g of bromomethylpyrene were added instead of 6.6 g of propargyl bromide. w was 3,600.

[0118] [ka]

[0119] [Example 1-5] (Synthesis of Polymer (A-5)) A reaction vessel was charged with 3.0 g of polymer (A-1), 30.0 g of methyl isobutyl ketone, 20.0 g of tetrahydrofuran, 1.5 g of m-ethynylbenzaldehyde, and 0.7 g of tetrabutylammonium bromide under a nitrogen atmosphere and stirred for several minutes. Next, 5.6 g of tetramethylammonium hydroxide (25% aqueous solution) was slowly added dropwise at room temperature. After the addition was complete, the reaction was continued for another 12 hours at room temperature. After the reaction was complete, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The resulting mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-5) represented by the following formula (A-5). The Mw of the polymer (A-5) was 3,700.

[0120] [ka]

[0121] Examples 1-6 to 1-11 (Synthesis of Polymers (A-6) to (A-11)) Instead of 1.5 g of m-ethynylbenzaldehyde, various aldehydes such as 2.9 g of 1-pyrenecarboxaldehyde, 2.3 g of biphenyl-4-carboxaldehyde, 1.6 g of 4-fluorobenzaldehyde, 2.0 g of piperonal, 1.7 g of 4-formylbenzonitrile, and 2.1 g of 3,4,5-trihydroxybenzaldehyde were used, and the reaction was carried out under the same conditions as in [Example 1-5], to obtain polymers (A-6) to (A-11) corresponding to the following formulae.

[0122] [ka]

[0123] [Examples 1-12 to 1-13] (Synthesis of Polymers (A-12) to (A-13)) The reaction was carried out under the same conditions as in Example 1-1, except that 10.0 g of 1-hydroxypyrene was replaced with 4.3 g of phenol and 6.6 g of naphthol, to obtain the corresponding polymers (A-12) and (A-13). The Mw of polymer (A-12) was 2,900. The Mw of polymer (A-13) was 2,300.

[0124] [ka]

[0125] [Example 1-14] (Synthesis of Polymer (A-14)) A reaction vessel was charged with 15.0 g of 1-hydroxypyrene, 6.7 g of 2-fluorenecarboxaldehyde, 6.3 g of biphenyl-4-carboxaldehyde, and 80.0 g of 1-butanol under a nitrogen atmosphere and heated to 80°C to dissolve. A solution of 3.3 g of p-toluenesulfonic acid monohydrate in 5.0 g of 1-butanol 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 100 g of methyl isobutyl ketone and 200 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The polymer was then dried in a vacuum dryer at 60°C for 12 hours to obtain a polymer. 3.0 g of the resulting polymer was transferred to a reaction vessel, and 20 g of methyl isobutyl ketone, 10 g of tetrahydrofuran, 1.0 g of m-ethynylbenzaldehyde, and 0.5 g of tetrabutylammonium bromide were added and stirred for several minutes to dissolve the polymer. Next, 3.7 g of tetramethylammonium hydroxide (25% aqueous solution) was slowly added dropwise at room temperature. After the addition was complete, the reaction was continued for another 12 hours at room temperature. After the reaction was complete, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-14) represented by the following formula (A-14). The Mw of the polymer (A-14) was 3,400.

[0126] [ka]

[0127] In the above formula (A-14), the number attached to each repeating unit indicates the content (mol %) of that repeating unit.

[0128] [Examples 1-15] (Synthesis of polymer (A-15)) A reaction vessel was charged with 9.0 g of 9,9-bis(4-hydroxyphenyl)fluorene, 5.0 g of 2-fluorenecarboxaldehyde, and 37.0 g of 1-butanol under a nitrogen atmosphere and heated to 80°C to dissolve. A solution of 1.2 g of p-toluenesulfonic acid monohydrate in 5.0 g of 1-butanol 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 using an evaporator, 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 resulting mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-15) represented by the following formula (A-15). The Mw of the polymer (A-15) was 2,500.

[0129] [ka]

[0130] [Example 1-16] (Synthesis of Polymer (A-16)) A reaction vessel was charged with 10.0 g of 1-hydroxypyrene, 4.5 g of 2-fluorenecarboxaldehyde, 5.1 g of N-ethylcarbazole-3-carboxaldehyde, and 53.0 g of 1-butanol under a nitrogen atmosphere and heated to 80°C to dissolve. A solution of 0.8 g of p-toluenesulfonic acid monohydrate in 5.0 g of 1-butanol 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 100 g of methyl isobutyl ketone and 200 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The resulting mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-16) represented by the following formula (A-16). The Mw of the polymer (A-16) was 2,100.

[0131] [ka]

[0132] In the above formula (A-16), the number attached to each repeating unit indicates the content (mol %) of that repeating unit.

[0133] [Example 1-17] (Synthesis of Polymer (A-17)) A reaction vessel was charged with 8.4 g of pyrene, 8.1 g of 2-fluorenecarboxaldehyde, and 65.0 g of 1,2-dichloroethane under a nitrogen atmosphere and dissolved. 6.3 g of methanesulfonic acid was added to the reaction vessel, which was then heated to 80°C and reacted for 5 hours. After the reaction was completed, the mixture was added dropwise to 300 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 dried at 60°C for 12 hours using a vacuum dryer to obtain polymer (A-17) represented by the following formula (A-17). The Mw of polymer (A-17) was 2,500.

[0134] [ka]

[0135] [Example 1-18] (Synthesis of Polymer (A-18)) A reaction vessel was charged with 3.0 g of polymer (A-17), 30.0 g of methyl isobutyl ketone, 20.0 g of tetrahydrofuran, 1.5 g of m-ethynylbenzaldehyde, and 0.7 g of tetrabutylammonium bromide under a nitrogen atmosphere and stirred for several minutes. Next, 5.6 g of tetramethylammonium hydroxide (25% aqueous solution) was slowly added dropwise at room temperature. After the addition was complete, the reaction was continued for an additional 6 hours at room temperature. After the reaction was complete, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The resulting mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-18) represented by the following formula (A-18). The Mw of the polymer (A-18) was 3,200.

[0136] [ka]

[0137] [Example 1-19] (Synthesis of Polymer (A-19)) Using 2.9 g of 1-pyrenecarboxaldehyde instead of 1.5 g of m-ethynylbenzaldehyde, the reaction was carried out under the same conditions as in Example 1-18 to obtain polymer (A-19) having the following formula: The Mw of polymer (A-19) was 3,300.

[0138] [ka]

[0139] [Example 1-20] (Synthesis of Polymer (A-20)) A reaction vessel was charged with 5.0 g of polymer (A-17), 40.0 g of cyclopentyl methyl ether, 1.2 g of tetramethylammonium bromide, and 8.8 g of 50% aqueous NaOH solution, and the mixture was stirred at room temperature for several minutes under a nitrogen atmosphere to dissolve the polymer (A-17). 4.4 g of propargyl bromide was added, and the mixture was heated from room temperature to 90°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-20) represented by the following formula (A-20). The Mw of polymer (A-20) was 3,000.

[0140] [ka]

[0141] [Example 1-21] (Synthesis of Polymer (A-21)) A reaction vessel was charged with 5.0 g of polymer (A-1), 40.0 g of N,N-dimethylacetamide, 1.2 g of tetramethylammonium bromide, and 6.1 g of potassium tert-butoxide, and the mixture was stirred at room temperature for several minutes under a nitrogen atmosphere to dissolve polymer (A-1). 7.3 g of 1-bromo-2-butyne was added, and the mixture was heated from room temperature to 90°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of 5% aqueous oxalic acid were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-21) represented by the following formula (A-21). The Mw of polymer (A-21) was 3,150.

[0142] [ka]

[0143] [Example 1-22] (Synthesis of Polymer (A-22)) A reaction vessel was charged with 5.0 g of polymer (A-17), 40.0 g of N,N-dimethylacetamide, 0.8 g of tetramethylammonium bromide, and 4.0 g of potassium tert-butoxide, and the mixture was stirred at room temperature for several minutes under a nitrogen atmosphere to dissolve the polymer (A-17). 4.8 g of 1-bromo-2-butyne was added, and the mixture was heated from room temperature to 90°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of cyclohexanone and 200 g of 5% aqueous oxalic acid solution were added, followed by washing the organic phase several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-22) represented by the following formula (A-22). The Mw of the polymer (A-22) was 2,900.

[0144] [ka]

[0145] [Example 1-23] (Synthesis of Polymer (A-23)) 5.0 g of polymer (A-11), 40.0 g of N,N-dimethylacetamide, 1.2 g of tetramethylammonium bromide, and 9.2 g of potassium tert-butoxide were added to a reaction vessel and stirred at room temperature for several minutes under a nitrogen atmosphere to dissolve polymer (A-11). 9.9 g of propargyl bromide was added, and the mixture was heated from room temperature to 90°C for 6 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of cyclohexanone and 200 g of 5% aqueous oxalic acid were added and the organic phase was washed several times. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator and added dropwise to 300 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 dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (A-23) represented by the following formula (A-23). ​​The Mw of polymer (A-23) was 3,100.

[0146] [ka]

[0147] [Example 1-24] (Synthesis of Polymer (A-24)) Using 11.0 g of 1-bromo-2-butyne instead of 9.9 g of propargyl bromide, a reaction was carried out under the same conditions as in Example 1-23 to obtain polymer (A-24) having the following formula: The Mw of polymer (A-24) was 3,100.

[0148] [ka]

[0149] Comparative Synthesis Example 1-1 (Synthesis of Polymer (x-1)) In a nitrogen atmosphere, 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, and the mixture was reacted at 100°C for 3 hours and then at 180°C for 1 hour. After that, unreacted monomers were removed under reduced pressure to obtain polymer (x-1) represented by the following formula (x-1). The Mw of the obtained polymer (x-1) was 11,000.

[0150] [ka]

[0151] Comparative Synthesis Example 1-2 (Synthesis of Polymer (x-2)) A reaction vessel was charged with 8.0 g of 9,9-bis(4-hydroxyphenyl)fluorene, 0.8 g of paraformaldehyde, and 21.5 g of methyl isobutyl ketone, and the mixture was heated to 80°C under a nitrogen atmosphere to dissolve the compounds. A solution of 0.8 g of p-toluenesulfonic acid monohydrate in 5.0 g of methyl isobutyl ketone was added to the reaction vessel, which was then heated to 115°C and reacted for 15 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel, and 100 g of methyl isobutyl ketone and 200 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was concentrated using an evaporator, and the residue was added dropwise to 300 g of methanol to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of methanol. The resulting mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain polymer (x-2) represented by the following formula (x-2). The Mw of the resulting polymer (x-2) was 8,000.

[0152] [ka]

[0153] <Preparation of Composition> The polymer [A], the solvent [B], the acid generator [C] and the crosslinking agent [D] used in the preparation of the composition are shown below.

[0154] [[A] Polymer] Example: Compounds (A-1) to (A-24) synthesized above Comparative Example: Polymer (x-1) and Polymer (x-2) Synthesized Above

[0155] [[B] Solvent] B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0156] [[C] Acid generator] C-1: bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate (compound represented by the following formula (C-1))

[0157] [ka]

[0158] [[D] Crosslinker] D-1: A compound represented by the following formula (D-1):

[0159] [ka]

[0160] D-2: A compound represented by the following formula (D-2):

[0161] [ka]

[0162] [Example 2-1] 10 parts by mass of (A-1) as the polymer [A] was dissolved in 90 parts by mass of (B-1) as the solvent [B], and the resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0163] [Examples 2-2 to 2-29 and Comparative Examples 2-1 to 2-2] Compositions (J-2) to (J-29) 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 were used as shown in Table 1. In Table 1, a "-" in the columns "Polymer (A)," "Acid generator (C)," and "Crosslinking agent (D)" indicates that the corresponding component was not used.

[0164] [Table 1]

[0165] <Evaluation> The etching resistance, heat resistance, and bending resistance of the obtained compositions were evaluated by the following methods. The evaluation results are shown in Table 2 below.

[0166] [Etching resistance] The composition prepared above was applied to a silicon wafer (substrate) by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). Next, the substrate was heated at 350°C for 60 seconds in an air atmosphere, followed by cooling at 23°C for 60 seconds to form a film with an average thickness of 200 nm, yielding a film-coated substrate. The film on the obtained film-coated substrate was treated using an etching device (Tokyo Electron Limited's "TACTRAS") under the following conditions: CF4 / Ar = 110 / 440 sccm, PRESS = 30 MT, HF RF (plasma generation high frequency power) = 500 W, LF RF (bias high frequency power) = 3000 W, DCS = -150 V, RDC (gas center flow ratio) = 50%, for 30 seconds. The etching rate (nm / min) was calculated from the average film thickness before and after treatment. Next, the ratio to the etching rate of Comparative Example 2-1 was calculated using the etching rate of Comparative Example 2-1 as a standard, and this ratio was used as a measure of etching resistance. The etching resistance was evaluated as "A" (very good) when the ratio was 0.90 or less, "B" (good) when it was more than 0.90 but less than 0.92, and "C" (poor) when it was 0.92 or more. In Table 2, "-" indicates that this is the evaluation standard for etching resistance.

[0167] [Heat resistance] The composition prepared above was applied to a silicon wafer (substrate) by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). Next, the substrate was heated at 200°C for 60 seconds in an air atmosphere, and then cooled at 23°C for 60 seconds to form a film with an average thickness of 200 nm, yielding a film-coated substrate on which a film was formed. The film on the obtained film-coated substrate was scraped to recover powder, and the recovered powder was placed in a container used for measurement using a TG-DTA device (NETZSCH's "TG-DTA2000SR"), and the mass before heating was measured. Next, using the TG-DTA device, the substrate was heated to 400°C at a heating rate of 10°C / min in a nitrogen atmosphere, and the mass of the powder at 400°C was measured. The mass loss rate (%) was then measured using the following formula, and this mass loss rate was used as a measure of heat resistance. M L ={(m1-m2) / m1}×100 In the above formula, M L is the mass loss rate (%), m1 is the mass (mg) before heating, and m2 is the mass (mg) at 400°C. The smaller the mass loss rate of the sample powder, the less sublimate and film decomposition products are generated when the film is heated, and the better the heat resistance. In other words, the smaller the mass loss rate, the higher the heat resistance. Heat resistance was evaluated as "A" (very good) when the mass loss rate was less than 5%, "B" (good) when it was 5% to 10%, and "C" (poor) when it was 10% or more.

[0168] [Bending resistance] The composition prepared above was applied by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") onto a silicon substrate on which a silicon dioxide film with an average thickness of 500 nm had been formed. Next, the substrate was heated at 350°C for 60 seconds in an atmospheric atmosphere, and then cooled at 23°C for 60 seconds, thereby obtaining a substrate with a resist underlayer film with an average thickness of 200 nm. A silicon-containing film-forming composition (JSR Corporation's "NFC SOG080") was applied by spin coating onto the obtained substrate with a resist underlayer film with an average thickness of 50 nm. The substrate was then heated at 200°C for 60 seconds in an atmospheric atmosphere, and then further heated at 300°C for 60 seconds, thereby forming a silicon-containing film with an average thickness of 50 nm. An ArF resist composition (JSR Corporation's "AR1682J") was applied onto the silicon-containing film by spin coating and heated (baked) at 130°C for 60 seconds in an air atmosphere to form a resist film with an average thickness of 200 nm. The resist film was exposed to light using an ArF excimer laser exposure device (lens numerical aperture 0.78, exposure wavelength 193 nm) through a 1:1 line-and-space mask pattern with a target size of 100 nm, varying the exposure dose, and then heated (baked) at 130°C for 60 seconds in an air atmosphere. The resist film was then developed using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) at 25°C for 1 minute, washed with water, and dried to obtain a substrate on which a line-and-space resist pattern with a 200 nm pitch and line widths of 30 nm to 100 nm was formed.

[0169] Using the resist pattern as a mask, the silicon-containing film was etched using the etching system under the following conditions: CF4 = 200 sccm, PRESS = 85 mT, HF RF (plasma generation high frequency power) = 500 W, LF RF (bias high frequency power) = 0 W, DCS = -150 V, RDC (gas center flow ratio) = 50%, to obtain a substrate with a pattern formed in the silicon-containing film. Next, using the silicon-containing film pattern as a mask, the resist underlayer film was etched using the etching system under the following conditions: O2 = 400 sccm, PRESS = 25 mT, HF RF (plasma generation high frequency power) = 400 W, LF RF (bias high frequency power) = 0 W, DCS = 0 V, RDC (gas center flow ratio) = 50%, to obtain a substrate with a pattern formed in the resist underlayer film. Using the resist underlayer film pattern as a mask, the silicon dioxide film was etched using the above etching apparatus under the following conditions: CF4 = 180 sccm, Ar = 360 sccm, PRESS. = 150 mT, HF RF (high frequency power for plasma generation) = 1,000 W, LF RF (high frequency power for bias) = ​​1,000 W, DCS = -150 V, RDC (gas center flow ratio) = 50%, for 60 seconds, to obtain a substrate with a pattern formed in the silicon dioxide film.

[0170] Then, for the substrate with the pattern formed on the silicon dioxide film, images of the resist underlayer film pattern shape for each line width were obtained at 250,000x magnification using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4000"), and the images were processed to obtain LER (line edge roughness). Ten line width direction positions Xn (n = 1 to 10) were measured at 100 nm intervals on the lateral side 3a of the 1,000 nm long resist underlayer film pattern 3 (line pattern), and the standard deviation calculated from the average position Xa of these line width direction positions was tripled to obtain 3 sigma. LER, which indicates the degree of curvature of the resist underlayer film pattern, increases as the line width of the resist underlayer film pattern becomes narrower. The bending resistance was evaluated as "A" (good) when the line width of the film pattern with an LER of 5.5 nm was less than 40.0 nm, "B" (fairly good) when it was 40.0 nm or more but less than 45.0 nm, and "C" (poor) when it was 45.0 nm or more. Note that the degree of bending of the film pattern shown in Figure 1 is exaggerated compared to the actual state.

[0171] [Table 2]

[0172] As can be seen from the results in Table 2, the resist underlayer films formed from the compositions of the examples were superior in etching resistance, heat resistance, and bending resistance compared to the resist underlayer films formed from the compositions of the comparative examples. [Industrial Applicability]

[0173] According to the method for producing a semiconductor substrate of the present invention, a well-patterned substrate can be obtained. The composition of the present invention can form a resist underlayer film having excellent etching resistance, heat resistance, and bending resistance. The polymer of the present invention can be suitably used as a component of a composition for forming a resist underlayer film. The method for producing a polymer of the present invention can efficiently produce a polymer suitable as a component of a composition for forming a resist underlayer film. Therefore, these can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future. [Explanation of symbols]

[0174] 3. Resist underlayer film pattern 3a Lateral side of resist underlayer film pattern

Claims

1. a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step; a step of performing etching using the resist pattern as a mask; Including, Before forming the resist pattern, A step of forming a silicon-containing film directly or indirectly on the resist underlayer film. further comprising The composition for forming a resist underlayer film, a polymer having a repeating unit represented by the following formula (1); Solvent and A method for manufacturing a semiconductor substrate, comprising: 【Chemistry 1】 (In formula (1), Ar １ is a divalent group having an aromatic ring with 5 to 40 ring members. ０ is a group represented by the following formula (1-1): 【Chemistry 2】 In formula (1-1), X 1 is a group represented by the following formula (i) or (ii). * represents a bond to the carbon atom in formula (1). ２ and Ar 3 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formula (1-1). 【Transformation 3】 (In formula (i), R １ and R ２ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ is a monovalent organic group having 1 to 20 carbon atoms.

2. A step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step; a step of performing etching using the resist pattern as a mask; Including, Before forming the resist pattern, A step of forming a silicon-containing film directly or indirectly on the resist underlayer film. The composition for forming a resist underlayer film used in a method for producing a semiconductor substrate further comprises: a polymer having a repeating unit represented by the following formula (1); Solvent and A composition for forming a resist underlayer film, comprising: 【Chemistry 4】 (In formula (1), Ar １ is a divalent group having an aromatic ring with 5 to 40 ring members. ０ is a group represented by the following formula (1-1): 【Transformation 5】 In formula (1-1), X 1 is a group represented by the following formula (i) or (ii). * represents a bond to the carbon atom in formula (1). ２ and Ar 3 are each independently a substituted or unsubstituted aromatic ring having 6 to 20 ring members that forms a fused ring structure together with two adjacent carbon atoms in the above formula (1-1). 【Transformation 6】 (In formula (i), R １ and R ２ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. In formula (ii), R ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ is a monovalent organic group having 1 to 20 carbon atoms.

3. The above Ar １ 3. The composition for forming a resist underlayer film according to claim 2, wherein the aromatic ring is 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.

4. The above Ar １ has at least one group selected from the group consisting of a hydroxy group, a group represented by the following formula (2-1), and a group represented by the following formula (2-2): 【Transformation 7】 (In formulas (2-1) and (2-2), R ７ are each independently a divalent organic group having 1 to 20 carbon atoms or a single bond. * represents a bond to a carbon atom in the aromatic ring.

5. The composition for forming a resist underlayer film according to any one of claims 2 to 4, wherein the polymer further has a repeating unit represented by the following formula (3): 【Transformation 8】 (In formula (3), Ar ５ is a divalent group having an aromatic ring with 5 to 40 ring members. １ is a hydrogen atom or a monovalent organic group having 1 to 60 carbon atoms (provided that R ０ Excluding groups that fall under the following.)

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