Method for producing semiconductor substrate and composition

Abstract

The present invention provides: a method for producing a semiconductor substrate, with which it is possible to form a film that has excellent embeddability and excellent flatness; and a composition. This method for producing a semiconductor substrate comprises a resist underlayer film-forming composition coating step, a resist pattern forming step, and an etching step, wherein the resist underlayer film-forming composition contains a solvent and a polymer that has, as repeating units, two or more structural units represented by formula (1) and two or more structural units represented by formula (2). (In the formulae, Ar1 is an n-valent organic group that has at least one aromatic ring having 3 to 20 carbon atoms. X is an m-valent organic group. n and m are integers of 2 to 5. The * in formula (1) and ** in formula (2) are bonded. At least one selected from the group consisting of Ar1 and X has a crosslinkable group.)

Description

Semiconductor substrate manufacturing method and composition

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

[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 (see Japanese Patent No. 5894106).

[0004] Patent No. 5894106

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

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a semiconductor substrate and a composition that can form a film that has excellent embedding properties and flatness.

[0007] In one embodiment, the present invention relates to a method for producing a semiconductor substrate, comprising: a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step; and a step of performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains: a polymer (hereinafter also referred to as a "polymer [A]") having two or more repeating units of a structural unit represented by the following formula (1) (hereinafter also referred to as a "structural unit (1)") and a structural unit (hereinafter also referred to as a "structural unit (2)") represented by the following formula (2): (In formula (1), Ar １ is an n-valent organic group having at least one aromatic ring having 3 to 20 carbon atoms. n is an integer of 2 to 5. * is a bond bonding to the structural unit represented by the formula (2) at ** in the formula (2). In the formula (2), X is an m-valent organic group. m is an integer of 2 to 5. ** is a bond bonding to the structural unit represented by the formula (1) at * in the formula (1). Ar １ and X has a crosslinkable group.

[0008] In one embodiment, the present invention relates to a composition comprising: a polymer having, as repeating units, two or more structural units represented by the following formula (1) and two or more structural units represented by the following formula (2); and a solvent. (In formula (1), Ar １ is an n-valent organic group having at least one aromatic ring having 3 to 20 carbon atoms. n is an integer of 2 to 5. * is a bond bonding to the structural unit represented by the formula (2) at ** in the formula (2). In the formula (2), X is an m-valent organic group. m is an integer of 2 to 5. ** is a bond bonding to the structural unit represented by the formula (1) at * in the formula (1). Ar １ and X has a crosslinkable group.

[0009] As used herein, the term "organic group" refers to a group containing at least one carbon atom. A "fused ring" refers to a polycyclic structure formed by adjacent rings sharing one edge (two adjacent atoms). A "multi-ring" refers to a structure in which two rings are bonded by a single bond. A "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. A "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. An "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it does not have to be composed only of an alicyclic structure and may contain a chain structure as part of it). The term "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure (however, it does not have to be composed solely of an aromatic ring structure, and may also contain an alicyclic structure or a chain structure as part of it).

[0010] 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, a film having excellent filling properties and flatness can be formed. Therefore, these compositions can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0011] FIG. 10 is a schematic plan view for explaining a method for evaluating flatness.

[0012] The semiconductor substrate manufacturing method and composition according to each embodiment of the present invention will be described in detail below. Combinations of preferred aspects of the embodiments are also preferred.

[0013] <<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”).

[0014] 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").

[0015] The composition for forming a resist underlayer film used in the method for producing a semiconductor substrate and each step will be described below.

[0016] <<Composition for forming a resist underlayer film>> The composition for forming a resist underlayer film contains the polymer (A) and the solvent (B). The composition may contain any optional component within a range that does not impair the effects of the present invention.

[0017] The composition contains the polymer [A] and the solvent [B], and thus can form a film having excellent embedding ability and flatness, particularly on a hydrophobic substrate. 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.

[0018] Each component contained in the composition will be described below.

[0019] <Polymer [A]> The polymer [A] has two or more repeating units of the structural unit (1) and two or more repeating units of the structural unit (2). In other words, the polymer [A] has two or more repeating units of the structural unit (1) and two or more repeating units of the structural unit (2). The polymer [A] may have other structural units as long as the effects of the present invention are not impaired. The composition can contain one or two or more types of polymer [A].

[0020] The structural unit (1) is represented by the following formula (1), and the structural unit (2) is represented by the following formula (2).

[0021] (In formula (1), Ar １ is an n-valent organic group having at least one aromatic ring having 3 to 20 carbon atoms. n is an integer of 2 to 5. * is a bond bonding to the structural unit represented by the formula (2) at ** in the formula (2). In the formula (2), X is an m-valent organic group. m is an integer of 2 to 5. ** is a bond bonding to the structural unit represented by the formula (1) at * in the formula (1). Ar １ and X has a crosslinkable group.

[0022] In the above formula (1), Ar １ Examples of the aromatic ring having 3 to 20 carbon atoms in the formula (I) include aromatic hydrocarbon rings having 6 to 20 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, and a perylene ring; aromatic heterocycles having 3 to 20 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, a triazine ring, and a carbazole ring; and combinations thereof. These ring combinations may be fused rings, grouped rings, or spiro structures. Among these, the aromatic ring is preferably a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, or a combination thereof.

[0023] In the above formula (1), Ar １The number of aromatic rings in may be at least 1. The number of aromatic rings may be 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 or more. The upper limit of the number of aromatic rings may be 20, 18, or 15. The number of aromatic rings is preferably 1, 2, 3, 4, 5, 6, 7, or 8, more preferably 1, 2, 3, 4, 5, 6, or 7, even more preferably 2, 3, 4, 5, or 6, and particularly preferably 2, 3, 4, or 5.

[0024] In the above formula (1), Ar １ The n-valent organic group having an aromatic ring represented by the formula (I) is a group obtained by removing (n-1) hydrogen atoms from the monovalent organic group having an aromatic ring. Examples of the monovalent organic group having an aromatic ring include the monovalent organic group having 3 to 40 carbon atoms and having an aromatic ring.

[0025] Examples of the monovalent organic group having 3 to 40 carbon atoms include a monovalent hydrocarbon group having 3 to 40 carbon atoms, a group having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the end of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing substituent, and combinations thereof.

[0026] Examples of the monovalent hydrocarbon group having 3 to 40 carbon atoms include monovalent hydrocarbon groups having 1 to 40 carbon atoms that correspond to 3 to 40 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 40 carbon atoms include a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms as the aromatic ring, and combinations thereof.

[0027] Examples of the monovalent chain hydrocarbon group having 1 to 40 carbon atoms (hereinafter also referred to as "chain hydrocarbon group (1x)") include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, and tert-butyl group; alkenyl groups such as ethenyl group, propenyl group, and butenyl group; and alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

[0028] Examples of the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms (hereinafter also referred to as "alicyclic hydrocarbon group (2x)") 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.

[0029] The monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms as the aromatic ring (hereinafter also referred to as "aromatic hydrocarbon group (3x)") includes Ar １ A group in which one hydrogen atom has been removed from an aromatic hydrocarbon ring having 3 to 20 carbon atoms, as shown in the following formula (1), extended to a ring having 40 carbon atoms, can be suitably used. Examples of aromatic hydrocarbon rings having more than 20 carbon atoms include a benzoperylene ring, an indenopyrene ring, a coronene ring, and an ovalene ring.

[0030] Examples of heteroatoms constituting the divalent heteroatom-containing linking group or monovalent heteroatom-containing substituent include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, halogen atoms, etc. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0031] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, and combinations thereof, where R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0032] Examples of the monovalent heteroatom-containing substituent include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, a halogen atom, and a carboxy group.

[0033] Ar １ In addition to the above-mentioned monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms, the aromatic ring in Ar １A ring having 3 to 20 carbon atoms, as shown in the following formula (1), can be preferably employed, which is expanded to have 40 carbon atoms. The aromatic heterocycle may be interposed between carbon atoms constituting the organic group, or may exist as a substituent substituting a hydrogen atom of the organic group.

[0034] In the above formula (1), Ar １ is preferably an n-valent hydrocarbon group having 6 to 40 carbon atoms and having at least one aromatic hydrocarbon ring having 6 to 20 carbon atoms, or an n-valent group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a nitro group, an amino group, an alkoxy group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. １ is preferably an n-valent aromatic hydrocarbon group having 6 to 40 carbon atoms; or a group which is an n-valent group as a whole formed by combining an aromatic hydrocarbon having 6 to 40 carbon atoms with a chain hydrocarbon having 1 to 5 carbon atoms.

[0035] Examples of the alkoxy group include alkoxy groups having 1 to 10 carbon atoms, such as a methoxy group, an ethoxy group, and a propoxy group. Examples of the alkoxycarbonyl group include alkoxycarbonyl groups having 2 to 10 carbon atoms, such as a methoxycarbonyl group and an ethoxycarbonyl group. Examples of the acyl group include acyl groups having 2 to 10 carbon atoms, such as an acetyl group, a propionyl group, and a butyryl group. Examples of the acyloxy group include acyloxy groups having 2 to 10 carbon atoms, such as an acetyloxy group, a propionyloxy group, and a butyryloxy group.

[0036] Examples of the aromatic hydrocarbon having 6 to 40 carbon atoms include structures corresponding to the aromatic hydrocarbon group (3x). Among these, benzene, naphthalene, biphenyl, fluorene, anthracene, phenanthrene, pyrene, and coronene are preferred. １ In the formula, these aromatic hydrocarbons preferably have a valence of 1 to 4, more preferably valence of 2 to 4.

[0037] Examples of the chain hydrocarbon having 1 to 5 carbon atoms include structures corresponding to the chain hydrocarbon group (1x) having 1 to 5 carbon atoms. Among these, methane, ethane, propane, butane, and isobutane are preferred. １In the formula (I), these chain hydrocarbons preferably have a valence of 1 to 4.

[0038] n is preferably an integer of 2 to 4, and more preferably 2 or 3.

[0039] In the formula (2), the m-valent organic group represented by X is Ar in the formula (1). １ It is possible to suitably employ a group in which the n-valent organic group having an aromatic ring as shown in the following formula (1) is made m-valent. However, the m-valent organic group represented by X does not necessarily have to contain an aromatic ring.

[0040] In the above formula (2), X is preferably an m-valent hydrocarbon group having 1 to 20 carbon atoms, an m-valent aromatic heterocyclic group having 3 to 20 carbon atoms, or a group which is an m-valent group as a whole formed by combining the above hydrocarbon group or the above aromatic heterocyclic group with a divalent heteroatom-containing linking group.

[0041] The m-valent hydrocarbon group having 1 to 20 carbon atoms includes Ar in the above formula (1). １ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms shown in the above, groups in which m hydrogen atoms have been removed from a structure corresponding to 1 to 20 carbon atoms can be suitably used. Among these, as the m-valent hydrocarbon group having 1 to 20 carbon atoms, m-valent saturated or unsaturated chain hydrocarbon groups having 1 to 10 carbon atoms, m-valent aromatic hydrocarbon groups having 6 to 12 carbon atoms, and groups in which the chain hydrocarbon group and the aromatic hydrocarbon group are combined to form an m-valent group as a whole are preferred.

[0042] The m-valent aromatic heterocyclic group having 3 to 20 carbon atoms includes Ar in the above formula (1). １ Preferably usable are groups in which m hydrogen atoms have been removed from the aromatic heterocyclic ring having 3 to 20 carbon atoms shown as the aromatic ring in the above formula (1). Among these, the m-valent nitrogen-containing aromatic heterocyclic group having 3 to 10 carbon atoms is preferred.

[0043] The divalent heteroatom-containing linking group is Ar in the above formula (1). １ The divalent heteroatom-containing linking group shown in the n-valent organic group having an aromatic ring represented by the following formula can be suitably used.

[0044] m is preferably an integer of 2 to 4, and more preferably 2 or 3.

[0045] In the above formula (1) and formula (2), Ar １ and X may have a crosslinkable group. １ has a crosslinkable group. The crosslinkable group is not particularly limited, and examples thereof include a vinyl group, an aldehyde group, a ketone group, a group having a Meldrum's acid structure, a group having a benzodioxole structure, a cyano group, a furyl group, a cyclic carbonate group, and a maleimide group. The crosslinkable group is preferably a vinyl group.

[0046] In the above formula (1) and formula (2), it is preferable that n is 2 and m is 2, or n is 2 and m is 3 or 4, or n is 3 or 4 and m is 2.

[0047] The polymer (A) preferably has, as a repeating unit, two or more of the structural unit represented by the following formula (3-1), the structural unit represented by the following formula (3-2), or the structural unit represented by the following formula (3-3). (In formula (3-1), Ar １ is a divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a divalent organic group. In formula (3-2), Ar １ is a trivalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a divalent organic group. Multiple Xs may be the same or different. In formula (3-3), Ar １ is a divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a trivalent organic group. １ In formulas (3-1), (3-2) and (3-3), Ar １ and X has a crosslinkable group. * and ** have the same meanings as in the above formulas (1) and (2), respectively.

[0048] In the above formula (3-1), Ar １ As the divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms, the following can be used: Ar １The organic group shown in the following formula (I) can be suitably employed.

[0049] In the above formula (3-1), as the divalent organic group represented by X, the organic group shown as X in the above formula (2) can be suitably used, except that m is set to 2.

[0050] In the above formula (3-2), Ar １ The trivalent organic group having at least one aromatic ring having 3 to 20 carbon atoms, represented by the formula (1), is represented by the formula (1) except that n is 3. １ The organic group shown in the following formula (I) can be suitably employed.

[0051] In the above formula (3-2), as the divalent organic group represented by X, X in the above formula (3-1) can be suitably used.

[0052] In the above formula (3-3), Ar １ As the divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms, Ar in the above formula (3-1) １ can be suitably adopted.

[0053] In the above formula (3-3), as the trivalent organic group represented by X, the organic group shown as X in the above formula (2) can be suitably used, except that m is set to 3.

[0054] In the above formulas (3-1), (3-2) and (3-3), Ar １ At least one selected from the group consisting of Ar and X may have a crosslinkable group. １ The crosslinkable group preferably has a crosslinkable group. １ and a crosslinkable group that X may have.

[0055] Examples of the polymer (A) include compounds having structural units represented by the following formulae (A-1) to (A-38) as repeating units.

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] (In formulas (A-5), (A-13), (A-14), (A-16), (A-18) to (A-20), (A-28) to (A-33), (A-35), (A-37), and (A-38), * and ** have the same meanings as in the above formulas (1) and (2), respectively. In other formulas, * and ** are omitted.)

[0066] The lower limit of the weight-average molecular weight of the polymer (A) is preferably 1500, more preferably 2500, and even more preferably 3000. The upper limit of the weight-average molecular weight is preferably 10000, more preferably 8000, and even more preferably 7000. The method for measuring the weight-average molecular weight is as described in the Examples.

[0067] The content of the polymer [A] in the components other than the solvent in the composition is preferably 1% by mass or more. The content of the polymer [A] may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0068] <Method for Synthesizing Polymer [A]> The method for synthesizing the polymer [A] is not particularly limited, but a nucleophilic reaction between a polyol compound that provides the structural unit of the above formula (1) (hereinafter also referred to as “compound [a]”) and a polyhalide that provides the structural unit of the above formula (2) (hereinafter also referred to as “compound [b]”) can be suitably employed.

[0069] The compound (a) is preferably a compound represented by the following formula (a): (In formula (a), Ar １ and n have the same meanings as in formula (1) above.

[0070] In the above formula (a), Ar １ For n, the explanation for the above formula (1) can be suitably adopted.

[0071] Specific examples of the compound [a] include, but are not limited to, those represented by the following formulae (a-1) to (a-16).

[0072]

[0073]

[0074]

[0075] The compound [b] is preferably a compound represented by the following formula (b): (In formula (b), X and m are defined as in formula (2) above. Z is a halogen atom.)

[0076] In the above formula (b), the explanation for X and m in the above formula (2) can be suitably adopted.

[0077] In the above formula (b), examples of the halogen atom represented by Z include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, a chlorine atom and a bromine atom are preferred as the halogen atom.

[0078] Specific examples of the compound [b] include, but are not limited to, those represented by the following formulae (b-1) to (b-18).

[0079]

[0080]

[0081] The reaction between compound [a] and compound [b] can be carried out in a reaction solvent, preferably under an inert gas atmosphere such as a nitrogen gas atmosphere, according to a known method. Typically, compound [a] and compound [b] can be mixed and heated to carry out a batchwise reaction. The molar ratio of compound [a] and compound [b] in the reaction can be appropriately set taking into consideration the number of hydroxy groups in compound [a] and the number of halogen atoms in compound [b], etc. The lower limit of the reaction temperature is preferably 20°C, more preferably 40°C, and even more preferably 50°C. The upper limit of the reaction temperature is preferably 140°C, more preferably 120°C, and even more preferably 100°C. The reaction temperature may be set to a temperature at which the solvent refluxes. The lower limit of the reaction time is preferably 1 hour, preferably 2 hours, and even more preferably 5 hours. The upper limit of the reaction time is preferably 36 hours, preferably 24 hours, and more preferably 20 hours. An acid catalyst may be added during the reaction. The acid catalyst is not particularly limited, and known inorganic and organic acids can be used. After the reaction, the polymer (A) can be obtained through separation, purification, drying, etc. As the reaction solvent, the solvent (B) described below can be suitably used.

[0082] <Solvent (B)> 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.

[0083] 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.

[0084] 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.

[0085] Examples of ester-based solvents include carbonate-based solvents such as diethyl carbonate and propylene carbonate, acetate monoester-based solvents such as methyl acetate and ethyl acetate, lactone-based solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate-based solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate-based solvents such as methyl lactate and ethyl lactate.

[0086] 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.

[0087] 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.

[0088] 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 propylene glycol dimethyl ether, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether.

[0089] 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.

[0090] The solvent (B) is preferably an ester-based solvent or a ketone-based solvent, more preferably a polyhydric alcohol partial ether carboxylate-based solvent, a carbonate-based solvent, or a cyclic ketone-based solvent, and even more preferably propylene glycol monomethyl ether acetate, propylene carbonate, or cyclohexanone.

[0091] 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 98% by mass.

[0092] [Optional Components] The composition may contain optional components to the extent that the effects of the present invention are not impaired. Examples of optional components include resin additives, acid generators, crosslinking agents, surfactants, other polymers, and antifoaming agents. Known antifoaming agents can be used, including 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 can be determined appropriately depending on the type of optional component, etc.

[0093] [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 preferably filtering the resulting mixture through a membrane filter or the like having a pore size of 0.5 μm or less.

[0094] [Coating Step] 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.

[0095] 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).

[0096] 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. The surface of the substrate may be made hydrophobic by treating it with HMDS (hexamethyldisilazane) or the like.

[0097] 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.

[0098] [Heating Step] The method for manufacturing a semiconductor substrate may include a step of heating the coating film formed in the coating step. Heating the coating film promotes the formation of a resist underlayer film. More specifically, heating the coating film promotes the volatilization of the solvent (B).

[0099] The coating film may be heated in an air atmosphere or a nitrogen atmosphere. The lower limit of the heating temperature is preferably 150°C, more preferably 200°C, and even more preferably 250°C. The upper limit of the heating temperature is preferably 500°C, and more preferably 400°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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The lower limit of the plasma exposure time is preferably 10 seconds, more preferably 30 seconds, and even more preferably 1 minute, and the upper limit of the plasma exposure time is preferably 10 minutes, more preferably 5 minutes, and even more preferably 2 minutes.

[0104] The plasma may be, for example, H ２ Plasma is generated in an atmosphere of a mixed gas of H gas and Ar gas. ２ In addition to gas and Ar gas, CF ４ Gas and CH ４ A carbon-containing gas such as H ２ CF 4 instead of either or both of the gas and Ar. ４ Gas, NF ３ Gas, CHF ３ Gas, CO ２ Gas, CH ２ F ２ Gas, CH ４ Gas and C ４ F ８ At least one of the gases may be introduced.

[0105] 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.

[0106] 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 80 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 according to the method described in the Examples.

[0107] [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.

[0108] 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 from 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).

[0109] 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.

[0110] 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.

[0111] 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.

[0112] [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.

[0113] 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.

[0114] 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.

[0115] 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 ２Excimer 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.

[0116] 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.

[0117] 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 above as the solvent [B] of the composition.

[0118] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0119] [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.

[0120] 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 , S.F. ６ Fluorine-based gases such as Cl ２ , BCl ３ Chlorine gases such as O ２ , O ３ , H ２ Oxygen-based gases such as O, H ２ , N.H. ３ , 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, 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.

[0121] <<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.

[0122] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0123] [Weight-average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL" 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.

[0124] [Average Thickness of Resist Underlayer Film] The average thickness of the resist underlayer film was determined by measuring the film thickness at arbitrary nine 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 value of the film thicknesses.

[0125] <Synthesis of Polymer [A]> In the synthesis of Polymer [A], compounds (a-1) to (a-15) represented by the following formulas (a-1) to (a-15) were used as compound [a], which was a raw material compound, and compounds (b-1) to (b-16) represented by the following formulas (b-1) to (b-16) were used as compound [b].

[0126]

[0127]

[0128]

[0129]

[0130]

[0131] (Synthesis of Raw Material Compounds) [Synthesis Example 1-1] (Synthesis of Compound (a-8)) In a nitrogen atmosphere, 30.0 g of 2-amino-4,6-dihydroxypyrimidine, 26.5 g of sorbic acid, 65.3 g of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride, and 280 g of dimethylacetamide were added to a reaction vessel and reacted at 25°C for 8 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of 4-methyltetrahydropyran and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the obtained organic phase was washed several times with water. Thereafter, the mixture was concentrated using an evaporator, and the residue was added dropwise to 800 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. Thereafter, the mixture was dried in a vacuum dryer at 60°C for 12 hours to obtain Compound (a-8).

[0132] Synthesis Example 1-2 (Synthesis of Compound (a-11)) 30.0 g of 2,4-dihydroxybenzaldehyde, 31.3 g of Meldrum's acid, 652 mg of acetic acid, 925 mg of piperidine, and 300 g of ethanol were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 25° C. for 8 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the obtained organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 500 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 25° C. for 12 hours to obtain compound (a-11).

[0133] Synthesis Example 1-3 Synthesis of Compound (a-12) 30.0 g of 3',5'-dihydroxyacetophenone, 29.6 g of piperonal, and 300 g of ethanol were added to a reaction vessel under a nitrogen atmosphere, and 43.0 g of a 25% aqueous solution of tetramethylammonium hydroxide was added dropwise. The mixture was then reacted at 25°C for 8 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of a 5% aqueous solution of oxalic acid were added to separate the aqueous phase. The resulting organic phase was then washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 500 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (a-12).

[0134] Synthesis Example 1-4 (Synthesis of Compound (a-13)) 30.0 g of 4,4'-dihydroxybenzophenone, 9.25 g of malononitrile, 64.0 g of 1,8-diazabicyclo[5.4.0]-7-undecene, and 200 g of dimethylacetamide were added to a reaction vessel under a nitrogen atmosphere and reacted at 60°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of 4-methyltetrahydropyran and 400 g of a 5% aqueous oxalic acid solution were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 400 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (a-13).

[0135] Synthesis Example 1-5 (Synthesis of Compound (a-14)) 30.0 g of 2,7-dihydroxy-9H-fluoren-9-one, 9.34 g of malononitrile, 64.6 g of 1,8-diazabicyclo[5.4.0]-7-undecene, and 200 g of dimethylacetamide were added to a reaction vessel under a nitrogen atmosphere and reacted at 60°C for 12 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of 4-methyltetrahydropyran and 400 g of a 5% aqueous oxalic acid solution were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 400 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (a-14).

[0136] Synthesis Example 1-6 (Synthesis of Compound (b-16)) 30.0 g of 2,4,6-trichloro-5-pyrimidinecarboxaldehyde, 20.5 g of Meldrum's acid, 426 mg of acetic acid, 604 mg of piperidine, and 300 g of ethanol were placed in a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 60°C for 8 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 400 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (b-16).

[0137] (Synthesis of Polymer [A]) Compounds (A-1) to (A-32) as polymer [A] represented by the following formula were synthesized according to the procedure shown below.

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] (In formulas (A-5), (A-13), (A-14), (A-16), (A-18) to (A-20), and (A-28) to (A-32), * and ** have the same meanings as in formulas (1) and (2), respectively. In other formulas, * and ** are omitted.)

[0146] Example 1-1 (Synthesis of Compound (A-1)) 20.0 g of compound (a-1), 10.2 g of compound (b-1), 9.50 g of tetrabutylammonium bromide, 43.0 g of a 25% aqueous solution of tetramethylammonium hydroxide, and 90.6 g of methyl isobutyl ketone were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 100°C for 6 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 700 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (A-1). The Mw of compound (A-1) was 5,400.

[0147] [Examples 1-2 to 1-3, 1-5 to 1-9, 1-11 to 1-13, 1-15 to 1-23, 1-25, 1-28 to 1-32] (Synthesis of compounds (A-2) to (A-3), (A-5) to (A-9), (A-11) to (A-13), (A-15) to (A-23), (A-25), and (A-28) to (A-32)) Compounds (A-2) to (A-3), (A-5) to (A-9), (A-11) to (A-13), (A-15) to (A-23), (A-25), and (A-28) to (A-32) were obtained under the same reaction conditions as in Example 1-1, except that the types and amounts of raw material compounds shown in Table 1 below were used. The Mw of the obtained compounds is also shown in Table 1.

[0148] Example 1-4 (Synthesis of Compound (A-4)) 20.0 g of compound (a-1), 10.0 g of compound (b-4), 6.56 g of triethylamine, and 90.0 g of methyl isobutyl ketone were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 25°C for 8 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 700 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (A-4). The Mw of compound (A-4) was 3600.

[0149] [Examples 1-10, 1-14] (Synthesis of Compounds (A-10) and (A-14)) Compounds (A-10) and (A-14) were obtained under the same reaction conditions as in Example 1-4, except that the types and amounts of raw material compounds shown in Table 1 below were used. The Mw of the obtained compounds is also shown in Table 1.

[0150] Example 1-24 (Synthesis of Compound (A-24)) 20.0 g of compound (a-11), 15.3 g of compound (b-2), 12.2 g of tetrabutylammonium bromide, 55.2 g of a 25% aqueous solution of tetramethylammonium hydroxide, and 110 g of methyl isobutyl ketone were added to a reaction vessel under a nitrogen atmosphere, and the mixture was allowed to react at 60°C for 6 hours. After completion of the reaction, the reaction solution was transferred to a separatory funnel, and 800 g of methyl isobutyl ketone and 400 g of water were added to wash the organic phase. After separating the aqueous phase, the resulting organic phase was washed several times with water. The mixture was then concentrated using an evaporator, and the residue was added dropwise to 700 g of heptane to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 100 g of heptane. The mixture was then dried in a vacuum dryer at 60°C for 12 hours to obtain compound (A-24). The Mw of compound (A-24) was 4600.

[0151] [Examples 1-26, 1-27] (Synthesis of compounds (A-26) and (A-27)) Compounds (A-26) and (A-27) were obtained under the same reaction conditions as in Example 1-24, except that the types and amounts of raw material compounds shown in Table 1 below were used. The Mw of the obtained compounds is also shown in Table 1.

[0152] 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.

[0153]

[0154]

[0155] <Preparation of Composition> [A] polymer, [B] solvent, [C] resin additive, [D] acid generator, [E] crosslinking agent, [F] surfactant and other components used in preparing a composition for forming a resist underlayer film are shown below.

[0156] [[A] Polymer] A-1 to A-32: Compounds (A-1) to (A-32) synthesized above

[0157] [B] Solvents: B-1: Propylene glycol monomethyl ether acetate, B-2: Cyclohexanone, B-3: Propylene carbonate

[0158] [[C] Resin Additives] C-1: Compound represented by the following formula (C-1) C-2: Compound represented by the following formula (C-2) C-3: Compound represented by the following formula (C-3) C-4: Compound represented by the following formula (C-4)

[0159]

[0160] [[D] Acid Generator] D-1: A compound represented by the following formula (D-1):

[0161] [[E] Crosslinking Agent] E-1: A compound represented by the following formula (E-1): E-2: A compound represented by the following formula (E-2):

[0162] [[F] Surfactants] F-1: Compound represented by the following formula (F-1) F-2: "NBX-15" (compound represented by the following formula (F-2)) manufactured by Neos Co., Ltd.

[0163] Other components x-1: the polymer (x-1) synthesized above

[0164] [Example 2-1] 3 parts by mass of (A-1) as a polymer [A] and 0.75 parts by mass of (C-1) as a resin additive [C] were dissolved in 97 parts by mass of (B-1) as a 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).

[0165] Examples 2-2 to 2-43 and Comparative Example 2-1 Compositions (J-2) to (J-43) and (CJ-1) were prepared in the same manner as in Example 2-1, except that the types and amounts of each component were used as shown in Table 2. In Table 2, "-" indicates that the corresponding component was not used.

[0166]

[0167] <Evaluation> [Examples 3-1 to 3-43 and Comparative Example 3-1] Using the compositions prepared above, the embedding ability and flatness were evaluated by the following methods. The evaluation results are also shown in Table 3 below.

[0168] [Fillability] A substrate was prepared with a silicon dioxide trench pattern formed on its surface, measuring 65 nm deep and 20 and 25 nm wide. The surface of this substrate was then hydrophobized with HMDS (hexamethyldisilazane). The composition was then applied to the hydrophobized substrate by spin coating using a spin coater (Tokyo Electron Limited's "LITHIUS Pro Z"). The spin coater's rotation conditions were set to obtain a substrate with a film having an average thickness of 100 nm. The substrate was then heated at 300°C for 90 seconds in an air atmosphere, followed by cooling at 23°C for 60 seconds. The cross-sectional shape of the substrate was observed (200,000 magnification) using a scanning electron microscope (Hitachi High-Technologies Corporation's "S-4800") to evaluate its fillability. The embedding ability was evaluated as "A" (good) when the resist underlayer film was embedded to the bottom of the 20 nm wide space pattern on the substrate, "B" (fairly good) when it was not embedded to the bottom of the 20 nm wide space pattern but was embedded to the bottom of the 30 nm wide space pattern, and "C" (poor) when it was not embedded to the bottom of the 30 nm wide space pattern.

[0169] [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.

[0170]

[0171] As can be seen from the results in Table 3, the resist underlayer films formed from the compositions of the examples were superior in embedding ability and flatness compared to the comparative examples.

[0172] According to the method for producing a semiconductor substrate of the present invention, a resist underlayer film can be formed that not only has sufficient embedding ability to embed a substrate pattern but also has excellent flatness after embedding. The composition of the present invention can form a film that is excellent in both embedding ability and flatness. Therefore, these can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future.

[0173] 3 Resist underlayer film pattern 3a Side surface of resist underlayer film pattern

Claims

1. A method for producing a semiconductor substrate, comprising: a step of applying a composition for forming a resist underlayer film directly or indirectly to a substrate; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the application step; and a step of performing etching using the resist pattern as a mask, wherein the composition for forming a resist underlayer film contains: a polymer having two or more repeating units of a structural unit represented by the following formula (1) and two or more repeating units of a structural unit represented by the following formula (2): (In formula (1), Ar １ is an n-valent organic group having at least one aromatic ring having 3 to 20 carbon atoms. n is an integer of 2 to 5. * is a bond bonding to the structural unit represented by the formula (2) at ** in the formula (2). In the formula (2), X is an m-valent organic group. m is an integer of 2 to 5. ** is a bond bonding to the structural unit represented by the formula (1) at * in the formula (1). Ar １ and X has a crosslinkable group.

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 comprising: a polymer having two or more repeating units of a structural unit represented by the following formula (1) and two or more repeating units of a structural unit represented by the following formula (2); and a solvent. (In formula (1), Ar １ is an n-valent organic group having at least one aromatic ring having 3 to 20 carbon atoms. n is an integer of 2 to 5. * is a bond bonding to the structural unit represented by the formula (2) at ** in the formula (2). In the formula (2), X is an m-valent organic group. m is an integer of 2 to 5. ** is a bond bonding to the structural unit represented by the formula (1) at * in the formula (1). Ar １ and X has a crosslinkable group.

4. Ar in the above formula (1) １ The composition of claim 3 , wherein 5. The composition of claim 3, wherein said crosslinkable groups are vinyl groups.

6. The composition according to any one of claims 3 to 5, wherein the polymer has two or more repeating units selected from the structural unit represented by the following formula (3-1), the structural unit represented by the following formula (3-2), and the structural unit represented by the following formula (3-3). (In formula (3-1), Ar １ is a divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a divalent organic group. In formula (3-2), Ar １ is a trivalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a divalent organic group. Multiple Xs may be the same or different. In formula (3-3), Ar １ is a divalent organic group having at least one aromatic ring having 3 to 20 carbon atoms. X is a trivalent organic group. １ In formulas (3-1), (3-2) and (3-3), Ar １ and X has a crosslinkable group. * and ** have the same meanings as in the above formulas (1) and (2), respectively.

7. In the above formula (1), Ar １ is an n-valent hydrocarbon group having 6 to 40 carbon atoms which has at least one aromatic hydrocarbon ring having 6 to 20 carbon atoms, or an n-valent group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with nitro groups, amino groups, alkoxy groups, alkoxycarbonyl groups, acyl groups, or acyloxy groups.

8. The composition according to any one of claims 3 to 5, wherein in the formula (1), the aromatic ring is a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, or a combination thereof.

9. The composition according to any one of claims 3 to 5, wherein in the above formula (2), X is an m-valent hydrocarbon group having 1 to 10 carbon atoms, or an m-valent group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with nitro groups, amino groups, alkoxy groups, alkoxycarbonyl groups, acyl groups, or acyloxy groups.

10. The composition according to any one of claims 3 to 5, wherein in the formula (1) and the formula (2), n is 2 and m is 2, or n is 2 and m is 3 or 4, or n is 3 or 4 and m is 2.

11. The composition according to any one of claims 3 to 5, wherein the content of said polymer in the components other than said solvent in said composition is 1 mass % or more.

12. The composition according to any one of claims 3 to 5, which is used for forming a resist underlayer film.

Images