Method for forming resist underlayer film, method for producing semiconductor substrate, composition for forming resist underlayer film, and resist underlayer film,

Abstract

The present invention provides: a method for forming a resist underlayer film, the method enabling the formation of a resist underlayer film that has excellent heat resistance and excellent flatness; a method for producing a semiconductor substrate; a composition for forming a resist underlayer film; and a resist underlayer film. A method for forming a resist underlayer film, the method comprising a step in which a substrate is directly or indirectly coated with a composition for forming a resist underlayer film and a heating step in which a coating film obtained by the coating step is heated at a temperature more than 450°C but not more than 600°C in an atmosphere that has an oxygen concentration of less than 0.01% by volume, wherein: the composition for forming a resist underlayer film contains a compound that has an aromatic ring, a polymer (excluding the compound that has an aromatic ring) that is thermally decomposed at least at a heating temperature in the heating step, and a solvent; the molecular weight of the compound that has an aromatic ring is 400 or more; and the content of the polymer is less than the content of the compound that has an aromatic ring in the composition for forming a resist underlayer film.

Description

Method for forming resist underlayer film, method for manufacturing semiconductor substrate, composition for forming resist underlayer film, and resist underlayer film

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

[0002] In the manufacture of semiconductor devices, a multilayer resist process is used to achieve high integration. In this process, a resist underlayer film-forming composition is first applied to a substrate to form a resist underlayer film, and a resist composition is then applied to the resist underlayer film to form a resist film. The resist film is then exposed to light through a mask pattern or the like and developed with an appropriate developer to form a resist pattern. The resist underlayer film is then dry-etched using the resist pattern as a mask, and the substrate is further dry-etched using the resulting resist underlayer film pattern as a mask, thereby forming a desired pattern on the substrate.

[0003] Generally, materials with a high carbon content are used for resist underlayer films. The use of such materials with a high carbon content for resist underlayer films improves etching resistance during substrate processing, thereby enabling more accurate pattern transfer. Thermosetting phenol novolak resins are well known as such resist underlayer films (see JP-A-2000-143937). It is also known that resist underlayer films formed from compositions for forming resist underlayer films containing acenaphthylene-based polymers exhibit excellent properties (see JP-A-2001-40293).

[0004] JP 2000-143937 A JP 2001-40293 A

[0005] As patterns become finer, resist underlayer films are required to have improved heat resistance and flatness.

[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 forming a resist underlayer film, which is capable of forming a resist underlayer film having excellent heat resistance and flatness, a method for producing a semiconductor substrate, a composition for forming a resist underlayer film, and a resist underlayer film.

[0007] In one embodiment, the present invention relates to a method for forming a resist underlayer film, comprising: 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"); and a heating step of heating the coated film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume (hereinafter also referred to as a "heating step"), wherein the composition for forming a resist underlayer film contains: a compound having an aromatic ring (hereinafter also referred to as a "compound [A]"); a polymer (excluding the compound having an aromatic ring) (hereinafter also referred to as a "polymer [B]") that thermally decomposes at least at the heating temperature in the heating step; and a solvent (hereinafter also referred to as a "solvent [C]"); the compound having an aromatic ring has a molecular weight of 400 or more; and the content of the polymer in the composition for forming a resist underlayer film is lower than the content of the compound having an aromatic ring.

[0008] 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 heating step of heating the coated film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step and the heating 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 compound having an aromatic ring; a polymer that thermally decomposes at least at the heating temperature in the heating step (excluding the case where the compound has an aromatic ring); and a solvent; the molecular weight of the compound having an aromatic ring is 400 or more; and the content of the polymer in the composition for forming a resist underlayer film is less than the content of the compound having an aromatic ring.

[0009] In one embodiment, the present invention relates to a composition for forming a resist underlayer film used in a method for forming a resist underlayer film, the composition comprising: a step of directly or indirectly applying a composition for forming a resist underlayer film directly or indirectly to a substrate; and a heating step of heating the coated film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume, the composition comprising: a compound having an aromatic ring; a polymer that thermally decomposes at least at the heating temperature in the heating step (excluding the compound having an aromatic ring); and a solvent, wherein the compound having an aromatic ring has a molecular weight of 400 or more, and the content of the polymer is less than the content of the compound having an aromatic ring.

[0010] In one embodiment, the present invention relates to a resist underlayer film formed from the composition for forming a resist underlayer film.

[0011] According to the method for forming a resist underlayer film, a resist underlayer film having excellent heat resistance and flatness can be formed. According to the method for producing a semiconductor substrate, a resist underlayer film having excellent heat resistance and flatness can be formed, thereby obtaining a good semiconductor substrate. According to the composition for forming a resist underlayer film, a resist underlayer film having excellent heat resistance and flatness can be formed. The resist underlayer film formed by the composition for forming a resist underlayer film has excellent heat resistance 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.

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

[0013] <<Method for forming a resist underlayer film>> The method for forming a resist underlayer film includes a coating step and a heating step. According to the method for forming a resist underlayer film, a resist underlayer film having excellent heat resistance and flatness can be formed. Each step will be described below.

[0014] [Coating Step] In this step, the composition for forming a resist underlayer film is coated directly or indirectly onto a substrate. By this step, a coating film of the composition for forming a resist underlayer film is formed directly or indirectly on the substrate. The composition for forming a resist underlayer film will be described later.

[0015] 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.

[0016] The method for applying the composition for forming a resist underlayer film is not particularly limited, and can be carried out by any appropriate method such as spin coating, casting coating, roll coating, etc., thereby forming a coating film.

[0017] 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.

[0018] [Heating Step] In this step, the coating film obtained in the coating step is heated at a temperature higher than 450° C. and not higher than 600° C. in an atmosphere having an oxygen concentration of less than 0.01% by volume.

[0019] The coating film is heated in a low-oxygen atmosphere. The heating temperature is greater than 450°C, preferably 460°C or higher, and more preferably 480°C or higher. The heating temperature is 600°C or lower, preferably 550°C or lower, and more preferably 520°C or lower. By setting the heating temperature within the above range, the resist underlayer film can be sufficiently baked and hardened, thereby improving heat resistance. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds, and even more preferably 45 seconds. The upper limit of the heating time is preferably 1,200 seconds, more preferably 600 seconds, and even more preferably 300 seconds.

[0020] The oxygen concentration during heating is less than 0.01% by volume, preferably 0.008% by volume or less, more preferably 0.006% by volume or less, even more preferably 0.004% by volume or less, and particularly preferably 0.003% by volume or less. By keeping the oxygen concentration during heating within this range, oxidation of the resist underlayer film can be suppressed, and the resist underlayer film can be favorably exhibited with the properties required for the resist underlayer film.

[0021] The atmosphere in which the coating film is heated is not particularly limited as long as the oxygen concentration satisfies the above-mentioned range, but a nitrogen atmosphere is preferred.

[0022] The coating film may be heated under conditions different from those of the heating step. The heating temperature is preferably 90°C or higher. The heating temperature is preferably 400°C or lower. The heating atmosphere may be either a low-oxygen atmosphere or an air atmosphere. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds, and even more preferably 45 seconds. The upper limit of the heating time is preferably 1,200 seconds, more preferably 600 seconds, and even more preferably 300 seconds. 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 method for measuring the average thickness of the resist underlayer film is as described in the Examples.

[0029] <<Composition for Forming Resist Underlayer Film>> The composition for forming a resist underlayer film contains a compound [A], a polymer [B], and a solvent [C]. The content of the polymer [B] in the composition for forming a resist underlayer film is less than the content of the compound [A]. The composition for forming a resist underlayer film may also contain optional components other than the compound [A], the polymer [B], and the solvent [C] (hereinafter simply referred to as "other optional components"), as long as the effects of the present invention are not impaired. Examples of the other optional components include an acid generator (hereinafter also referred to as "acid generator [D]"), a crosslinking agent (hereinafter also referred to as "crosslinking agent [E]"), an oxidizing agent (hereinafter also referred to as "oxidizing agent [F]"), a surfactant, an adhesion aid, and other polymers as additives.

[0030] By configuring the composition for forming a resist underlayer film as described above, it is possible to form a resist underlayer film that is excellent in heat resistance and flatness. The reason for this is not necessarily clear, but can be presumed as follows, for example. That is, by using the compound [A] in combination with the polymer [B] that thermally decomposes at least at the heating temperature in the heating step and controlling the relative amounts of the compound [A] and the polymer [B], the fluidity and compatibility of each component are improved, and the polymer [B] is thermally decomposed and disappears in the heating step, making it possible to suppress undesired film decomposition in subsequent steps, and as a result, it is thought that the heat resistance and flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be improved.

[0031] [Compound [A]] The compound [A] is a compound having an aromatic ring. The compound [A] is not particularly limited as long as it has an aromatic ring and a molecular weight of 400 or more. The compound [A] can be used alone or in combination of two or more.

[0032] The compound [A] may be a polymer having a structural unit containing an aromatic ring (hereinafter also referred to as "polymer [A]"), or may be a non-polymeric compound (i.e., an aromatic ring-containing compound). In this specification, a "polymer" refers to a compound having two or more structural units (repeating units), and an "aromatic ring-containing compound" refers to a compound containing an aromatic ring that does not fall under the category of the above-mentioned polymer.

[0033] Examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, an indene ring, a pyrene ring, a coronene ring, a fluorene ring, a fluorenylidene biphenyl ring, a fluorenylidene binaphthalene ring, a chrysene ring, a dibenzochrysene ring, or a combination thereof; and aromatic heterocycles such as a furan ring, a pyrrole ring, an indole 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, or a combination thereof.

[0034] The aromatic ring also includes an aromatic cyclic amide structure obtained by reacting an aromatic dicarboxylic acid or an aromatic dicarboxylic acid anhydride with an aromatic amine.

[0035] The lower limit of the molecular weight of the compound [A] is preferably 400. In this specification, the "molecular weight of the compound [A]" refers to the polystyrene equivalent weight average molecular weight (hereinafter also referred to as "Mw") measured by gel permeation chromatography (GPC) under the conditions described below when the compound [A] is a polymer [A], and refers to the molecular weight calculated from the structural formula when the compound [A] is an aromatic ring-containing compound.

[0036] When the compound [A] is an aromatic ring-containing compound, the aromatic ring-containing compound has one or more of the above aromatic rings repeated or in combination. In addition to a single bond, a divalent hydrocarbon group, -CO-, -NR'-, -O-, or a combination thereof may be present between the aromatic rings. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. When the compound [A] is an aromatic ring-containing compound, the lower limit of the molecular weight of the compound [A] is preferably 450, more preferably 500, even more preferably 550, and particularly preferably 600. The upper limit of the molecular weight of the compound [A] is preferably 1,500, more preferably 1,200, even more preferably 1,000, and particularly preferably 800.

[0037] The compound [A] is preferably a polymer [A]. By using the polymer [A] as the compound [A] in the composition, the coatability of the composition can be improved.

[0038] Examples of the polymer [A] include a polymer having an aromatic ring in the main chain, and a polymer having no aromatic ring in the main chain but having an aromatic ring in a side chain. The "main chain" refers to the longest chain of atoms in the polymer. The "side chain" refers to any chain other than the longest chain of atoms in the polymer.

[0039] Examples of the polymer (A) include polycondensation compounds and compounds obtained by reactions other than polycondensation.

[0040] Examples of the polymer (A) include novolak resins, resol resins, styrene resins, acenaphthylene resins, indene resins, arylene resins, triazine resins, calixarene resins, and polyamide resins.

[0041] (Novolac Resin) A novolac resin is a resin obtained by reacting a phenolic compound with an aldehyde or a divinyl compound using an acid catalyst. A plurality of phenolic compounds and aldehydes or divinyl compounds may be mixed and reacted.

[0042] Examples of the phenolic compound include phenols such as phenol, cresol, xylenol, resorcinol, bisphenol A, p-tert-butylphenol, p-octylphenol, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(3-hydroxyphenyl)fluorene, and 4,4'-(α-methylbenzylidene)bisphenol; naphthols such as α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,6-naphthalenediol, and 9,9-bis(6-hydroxynaphthyl)fluorene; anthrols such as 9-anthrol; and pyrenols such as 1-hydroxypyrene and 2-hydroxypyrene.

[0043] Examples of aldehydes include aldehydes such as formaldehyde, benzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde, 1-formylpyrene, and 4-biphenylaldehyde, and aldehyde sources such as paraformaldehyde and trioxane.

[0044] Examples of divinyl compounds include divinylbenzene, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, 5-vinylnorborna-2-ene, divinylpyrene, limonene, and 5-vinylnorbornadiene.

[0045] Examples of novolak resins include resins having structural units derived from phenol and formaldehyde, resins having structural units derived from cresol and formaldehyde, resins having structural units derived from dihydroxynaphthalene and formaldehyde, resins having structural units derived from fluorene bisphenol and formaldehyde, resins having structural units derived from fluorene bisnaphthol and formaldehyde, resins having structural units derived from hydroxypyrene and formaldehyde, resins having structural units derived from hydroxypyrene and naphthaldehyde, resins having structural units derived from 4,4'-(α-methylbenzylidene)bisphenol and formaldehyde, resins having structural units derived from a phenol compound and formylpyrene, resins combining these, and resins in which some or all of the hydrogen atoms of the phenolic hydroxyl groups of these resins have been substituted with propargyl groups or the like.

[0046] (Resole Resin) A resole resin is a resin obtained by reacting a phenolic compound with an aldehyde using an alkaline catalyst.

[0047] (Styrene Resin) The styrene resin is a resin having a structural unit derived from a compound having an aromatic ring and a polymerizable carbon-carbon double bond. In addition to the above structural units, the styrene resin may also have a structural unit derived from an acrylic monomer, a vinyl ether, or the like.

[0048] Examples of styrene resins include polystyrene, polyvinylnaphthalene, polyhydroxystyrene, polyphenyl(meth)acrylate, and resins made by combining these.

[0049] The acenaphthylene resin is a resin having structural units derived from a compound having an acenaphthylene skeleton.

[0050] Examples of acenaphthylene resins include copolymers of acenaphthylene and hydroxymethylacenaphthylene.

[0051] (Indene Resin) An indene resin is a resin having a structural unit derived from a compound having an indene skeleton.

[0052] (Arylene Resin) The arylene resin is a resin having a structural unit derived from a compound containing an arylene skeleton. Examples of the arylene skeleton include a phenylene skeleton, a naphthylene skeleton, and a biphenylene skeleton.

[0053] Examples of the arylene resin include polyarylene ether, polyarylene sulfide, polyarylene ether sulfone, polyarylene ether ketone, a resin having a structural unit containing a biphenylene skeleton, and a resin having a structural unit containing a biphenylene skeleton and a structural unit derived from a compound containing an acenaphthylene skeleton.

[0054] (Triazine Resin) The triazine resin is a resin having a structural unit derived from a compound having a triazine skeleton.

[0055] Examples of compounds having a triazine skeleton include melamine compounds and cyanuric acid compounds.

[0056] When the polymer [A] is a novolac resin, a resol resin, a styrene resin, an acenaphthylene resin, an indene resin, an arylene resin, or a triazine resin, the lower limit of the Mw of the polymer [A] is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 4,000. The upper limit of the Mw is preferably 100,000, more preferably 60,000, even more preferably 30,000, and particularly preferably 15,000. By setting the Mw of the polymer [A] within the above range, the flatness of the resist underlayer film can be further improved.

[0057] The upper limit of Mw / Mn (Mn is the number average molecular weight in terms of polystyrene measured by GPC) of the polymer (A) is preferably 5, more preferably 3, and still more preferably 2. The lower limit of Mw / Mn is usually 1, and preferably 1.2.

[0058] In this specification, the Mw and Mn of a polymer are measured by the method described in the Examples.

[0059] (Calixarene Resin) Calixarene resin is a cyclic oligomer in which multiple aromatic rings to which hydroxy groups are bonded are cyclically bonded via hydrocarbon groups, or a resin in which some or all of the hydrogen atoms of the hydroxy groups, aromatic rings, and hydrocarbon groups have been substituted.

[0060] Examples of calixarene resins include cyclic tetramers to dodecamers formed from phenolic compounds such as phenol and naphthol and formaldehyde, cyclic tetramers to dodecamers formed from phenolic compounds such as phenol and naphthol and benzaldehyde compounds, and resins in which the hydrogen atoms of the phenolic hydroxyl groups of these cyclic compounds have been substituted with propargyl groups or the like.

[0061] The lower limit of the molecular weight of the calixarene resin is preferably 500, more preferably 700, and even more preferably 1,000. The upper limit of the molecular weight is preferably 5,000, more preferably 3,000, and even more preferably 1,500.

[0062] (Polyamide Resin) The polyamide resin is a resin obtained by polycondensation reaction of a carboxylic acid or an acid anhydride with an amine. The lower limit of the molecular weight of the polyamide resin is preferably 800, more preferably 1,000, and even more preferably 2,000. The upper limit of the molecular weight is preferably 10,000, more preferably 8,000, and even more preferably 6,000.

[0063] The lower limit of the content of the compound [A] is preferably 80 mass %, more preferably 85 mass %, still more preferably 90 mass %, and particularly preferably 95 mass %, based on the total solid content of the components other than the solvent [C] in the composition for forming a resist underlayer film. The upper limit of the content is preferably 99 mass %. The compound [A] can be used alone or in combination of two or more.

[0064] (Method for synthesizing compound [A]) Compound [A] can be synthesized by a known method. Commercially available products may also be used.

[0065] [Polymer [B]] The polymer [B] is a polymer that thermally decomposes at least at the heating temperature in the heating step (excluding the case where it is a compound having an aromatic ring). In this specification, the term "thermally decomposing polymer" refers to a polymer that loses 95% or more of its weight when subjected to thermogravimetry (TGA) under conditions of a nitrogen atmosphere, a heating rate of 10°C / min, and a temperature range of more than 450°C and not more than 600°C.

[0066] Examples of the polymer (B) include acrylic polymers, polycarbonate polymers, cycloolefin polymers, cellulose polymers, and polyvinyl alcohol polymers. These materials can be used alone or in combination of two or more. Among these, acrylic polymers are preferred from the viewpoint of high thermal decomposition.

[0067] (Acrylic Polymer) The polymer [B] as an acrylic polymer preferably has a first structural unit (hereinafter also referred to as structural unit (I)). The polymer [B] may contain a second structural unit (hereinafter also referred to as structural unit (II)) or other structural units (hereinafter simply referred to as "other structural units") in addition to the structural unit (I). The polymer [B] may have one or more types of each structural unit.

[0068] (Structural Unit (I)) The structural unit (I) is a structural unit represented by the following formula (B1): When the polymer (B) has the structural unit (I), the fluidity of the composition for forming a resist underlayer film can be improved, and as a result, the heat resistance and flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be improved. (In formula (B1), R １ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ２ is a monovalent organic group having 1 to 20 carbon atoms.

[0069] R in the above formula (B1) １ and R ２Examples 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 containing a divalent heteroatom-containing group between the carbon atoms of this hydrocarbon group, and a group in which some or all of the hydrogen atoms of these groups have been substituted with a monovalent heteroatom-containing group. Examples of the divalent heteroatom-containing group include -O-, -CO-, -COO-, etc. Examples of the monovalent heteroatom-containing group include a hydroxy group, a halogen atom, a cyano group, a nitro group, etc.

[0070] In this specification, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "hydrocarbon group" also includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed solely 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, an alicyclic hydrocarbon group does not necessarily have to be composed solely 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, an aromatic hydrocarbon group does not necessarily have to be composed solely of an aromatic ring structure, and may contain a linear structure or an alicyclic structure as part of it.

[0071] R １ or R ２ In the formula (I), 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, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0072] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0073] 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, and bridged ring hydrocarbon groups such as a norbornyl group and an adamantyl group.

[0074] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl and naphthyl groups, and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0075] R １ or R ２ When has 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.

[0076] R １ is preferably a hydrogen atom or a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

[0077] R ２ is preferably a substituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a fluorine atom-substituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, and even more preferably a hexafluoroisopropyl group, a 2,2,2-trifluoroethyl group, or a 3,3,4,4,5,5,6,6-octafluorohexyl group. In this case, the flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved. In this specification, the term "fluorine atom-substituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms" refers to a group in which some or all of the hydrogen atoms of the chain hydrocarbon group have been substituted with fluorine atoms.

[0078] The lower limit of the content of the structural unit (I) in the polymer [B] is preferably 1 mol%, more preferably 15 mol%, and even more preferably 25 mol%, based on all structural units constituting the polymer [B]. The upper limit of the content is preferably 99 mol%, more preferably 85 mol%, and even more preferably 75 mol%. When the content of the structural unit (I) is within the above range, the flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved.

[0079] (Structural Unit (II)) The structural unit (II) is a structural unit represented by the following formula (B2): When the polymer (B) has the structural unit (II), it is possible to improve the compatibility with the compound (A), and as a result, it is possible to improve the heat resistance and flatness of the resist underlayer film formed from the composition for forming a resist underlayer film.

[0080]

[0081] In the above formula (B2), R ３ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. L is a single bond or a divalent linking group. Ar is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic ring having 6 to 20 ring members. R ４ is a monovalent hydroxyalkyl group or hydroxy group having 1 to 10 carbon atoms. n is an integer of 1 to 8. When n is 2 or more, multiple R ４ are the same or different.

[0082] R ３ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms in the formula (B1) include R １ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the same groups as those exemplified above.

[0083] R ３ When R has a substituent, examples of the substituent include R １ Examples of the substituent in the formula (I) include the same groups as those exemplified above.

[0084] R ３is preferably a hydrogen atom or a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or an unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

[0085] Examples of the divalent linking group for L include divalent hydrocarbon groups having 1 to 10 carbon atoms, such as -COO-, -CO-, -O-, and -CONH-.

[0086] L is preferably a single bond.

[0087] Examples of the aromatic ring having 6 to 20 ring members in Ar include the same rings as those exemplified as the aromatic rings contained in the compound (A) described above. In this specification, the term "number of ring members" refers to the number of atoms constituting the ring, and in the case of a polycyclic ring, refers to the number of atoms constituting the polycyclic ring.

[0088] When Ar has a substituent, examples of the substituent include R １ However, the same groups as those exemplified as the substituents in R ４ is not considered a substituent on Ar.

[0089] Ar is preferably a group in which (n+1) hydrogen atoms have been removed from an unsubstituted 6- to 20-membered aromatic ring, more preferably a group in which (n+1) hydrogen atoms have been removed from an unsubstituted 6- to 20-membered aromatic hydrocarbon ring, and even more preferably a group in which (n+1) hydrogen atoms have been removed from an unsubstituted benzene ring.

[0090] R ４ The monovalent hydroxyalkyl group having 1 to 10 carbon atoms is a group in which some or all of the hydrogen atoms of a monovalent alkyl group having 1 to 10 carbon atoms have been substituted with hydroxy groups.

[0091] R ４ R is preferably a monovalent hydroxyalkyl group having 1 to 10 carbon atoms, more preferably a monovalent monohydroxyalkyl group having 1 to 10 carbon atoms, and even more preferably a monohydroxymethyl group. ４ When the group is the above group, the flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved.

[0092] n is preferably 1 to 5, more preferably 1 to 3, still more preferably 1 or 2, and particularly preferably 1.

[0093] The lower limit of the content of the structural unit (II) in the polymer [B] is preferably 1 mol%, more preferably 15 mol%, and even more preferably 25 mol%, based on all structural units constituting the polymer [B]. The upper limit of the content is preferably 99 mol%, more preferably 85 mol%, and even more preferably 75 mol%. When the content of the structural unit (II) is within the above range, the flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved.

[0094] (Other Structural Units) Examples of other structural units include structural units derived from (meth)acrylic acid esters, structural units derived from (meth)acrylic acid, and structural units derived from acenaphthylene compounds.

[0095] When the polymer (B) has other structural units, the upper limit of the content of the other structural units is preferably 20 mol %, more preferably 5 mol %, based on all structural units constituting the polymer (B).

[0096] (Polycarbonate-Based Polymer) Examples of the polycarbonate-based polymer as the polymer [B] include aliphatic polycarbonate-based polymers that are composed of aliphatic chains and do not contain an aromatic compound (for example, a benzene ring) between the carbonate ester groups (-O-CO-O-) in the main chain, and aromatic polycarbonate-based polymers that contain an aromatic compound between the carbonate ester groups (-O-CO-O-) in the main chain. Among these, aliphatic polycarbonate-based polymers are preferred. Examples of aliphatic polycarbonate-based polymers include polyethylene carbonate and polypropylene carbonate. Examples of aromatic polycarbonate-based polymers include those that contain a bisphenol A structure in the main chain.

[0097] The lower limit of the Mw of the polymer [B] is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 3,500. The upper limit of the Mw is preferably 100,000, more preferably 50,000, even more preferably 30,000, and particularly preferably 20,000. By setting the Mw of the polymer [B] within the above range, the heat resistance and flatness of the resist underlayer film can be further improved.

[0098] The upper limit of Mw / Mn of the polymer (B) is preferably 5, more preferably 3, and even more preferably 2.5. The lower limit of Mw / Mn is usually 1, and preferably 1.2.

[0099] The content of the polymer [B] in the composition for forming a resist underlayer film is less than the content of the compound [A]. Preferably, it is 0.1 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the compound [A]. The lower limit of the content of the polymer [B] is more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 2 parts by mass, relative to 100 parts by mass of the compound [A]. The upper limit of the content is more preferably 40 parts by mass, even more preferably 30 parts by mass, and particularly preferably 25 parts by mass. When the content of the polymer [B] is within the above range, the heat resistance and flatness of the resist underlayer film formed from the composition for forming a resist underlayer film can be further improved.

[0100] (Method for synthesizing polymer [B]) When polymer [B] is an acrylic polymer, it can be synthesized by using, for example, a monomer that provides structural unit (I), and, if necessary, a monomer that provides structural unit (II) and a monomer that provides other structural units, in amounts that will yield predetermined content ratios, and polymerizing them by a known method.

[0101] [Solvent (C)] The composition for forming a resist underlayer film contains a solvent (C). The solvent (C) is not particularly limited as long as it can dissolve or disperse the compound (A) and the polymer (B), and any optional components contained as needed.

[0102] Examples of the solvent (C) include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, etc. The solvent (C) may be used alone or in combination of two or more.

[0103] Examples of the alcohol solvent include monoalcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, t-butanol, n-pentanol, iso-pentanol, sec-pentanol, and t-pentanol; and polyhydric alcohol solvents such as ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, and 2,4-heptanediol.

[0104] Examples of the ketone solvent include aliphatic ketone solvents such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, and methyl n-amyl ketone.

[0105] Examples of the amide solvent include cyclic amide solvents such as 1,3-dimethyl-2-imidazolidinone and N-methyl-2-pyrrolidone; and chain amide solvents such as formamide, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0106] Examples of the ether solvent include polyhydric alcohol (partial) ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, and diethylene glycol dibutyl ether; polyhydric alcohol partial ether acetate solvents such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monoethyl ether acetate; dialiphatic ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, and diisoamyl ether; aliphatic-aromatic ether solvents such as anisole and phenyl ethyl ether; and cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, and dioxane.

[0107] Examples of the ester solvent include carboxylic acid ester solvents such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, and ethyl acetoacetate; lactone solvents such as γ-butyrolactone and γ-valerolactone; polyhydric alcohol acetate solvents such as 1,6-diacetoxyhexane; and carbonate ester solvents such as diethyl carbonate and propylene carbonate.

[0108] Among these, ether-based solvents, ketone-based solvents, and ester-based solvents are preferred. As ether-based solvents, polyhydric alcohol (partial) ether-based solvents, polyhydric alcohol partial ether acetate-based solvents, and dialiphatic ether-based solvents are preferred, polyhydric alcohol (partial) ether-based solvents and polyhydric alcohol partial ether acetate-based solvents are more preferred, diethylene glycol dibutyl ether and propylene glycol monoalkyl ether acetate are even more preferred, and PGMEA is particularly preferred. As ketone-based solvents, cyclic ketone-based solvents are preferred, and cyclohexanone and cyclopentanone are more preferred. As ester-based solvents, carboxylic acid ester-based solvents, polyhydric alcohol acetate-based solvents, and lactone-based solvents are preferred, and 1,6-diacetoxyhexane and γ-butyrolactone are even more preferred.

[0109] Polyhydric alcohol partial ether acetate solvents, particularly propylene glycol monoalkyl ether acetates, particularly PGMEA, are preferred because their inclusion in the solvent [C] can improve the coatability of the resist underlayer film-forming composition to substrates such as silicon wafers. Since the compound [A] contained in the resist underlayer film-forming composition has high solubility in PGMEA or the like, adding a polyhydric alcohol partial ether acetate solvent to the solvent [C] can ensure that the resist underlayer film-forming composition (I) exhibits excellent coatability, thereby further improving the embedding ability of the resist underlayer film. The lower limit of the content of the polyhydric alcohol partial ether acetate solvent in the solvent [C] is preferably 20% by mass, more preferably 60% by mass, even more preferably 90% by mass, and particularly preferably 100% by mass.

[0110] [Acid Generator (D)] The acid generator (D) is a component that generates an acid under the action of heat or light, and promotes crosslinking of the compound (A). When the composition for forming a resist underlayer film contains the acid generator (D), the crosslinking reaction of the compound (A) is promoted, and the hardness of the formed film can be further increased. The acid generator (D) can be used alone or in combination of two or more.

[0111] [D] Examples of the acid generator include onium salt compounds and N-sulfonyloxyimide compounds.

[0112] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, and ammonium salts.

[0113] Examples of sulfonium salts include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, and 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate. sulfonate, 4-cyclohexylphenyl diphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyl diphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyl diphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyl diphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyl diphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, and the like.

[0114] Examples of tetrahydrothiophenium salts include 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium perfluoro-n-octanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium perfluoro-n-octanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium perfluoro-n-octanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, and the like.

[0115] Examples of iodonium salts include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate, bis(4-t-butylphenyl)iodonium perfluoro-n-octanesulfonate, bis(4-t-butylphenyl)iodonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate; Diphenyliodonium trifluoromethanecarboxylate, diphenyliodonium nonafluoro-n-butanecarboxylate, diphenyliodonium perfluoro-n-octanecarboxylate, diphenyliodonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanecarboxylate, bis(4-t-butylphenyl)iodonium trifluoromethanecarboxylate, bis(4-t-butylphenyl)iodonium nonafluoro-n-butanecarboxylate, bis(4-t-butylphenyl)iodonium perfluoro-n-octanecarboxylate, bis(4-t-butylphenyl)iodonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanecarboxylate, and the like.

[0116] Examples of the N-sulfonyloxyimide compound include N-(trifluoromethanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(nonafluoro-n-butanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(perfluoro-n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, and N-(2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide.

[0117] Examples of ammonium salts include tripropylammonium trifluoromethanesulfonate, tripropylammonium nonafluoro-n-butanesulfonate, tripropylammonium perfluoro-n-octanesulfonate, and tripropylammonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate.

[0118] Among these, the acid generator (D) is preferably an onium salt compound, more preferably an iodonium salt, and even more preferably bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate.

[0119] When the composition for forming a resist underlayer film contains the acid generator [D], the lower limit of the content of the acid generator [D] is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass, relative to 100 parts by mass of the compound [A]. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass, and even more preferably 8 parts by mass. By setting the content of the acid generator [D] within the above range, the crosslinking reaction of the compound [A] can be more effectively promoted.

[0120] [Crosslinking Agent (E)] The crosslinking agent (E) is a component that forms crosslinks between components such as the compound (A) under the action of heat or acid. In the composition for forming a resist underlayer film, the compound (A) may have an intermolecular bond-forming group, but by further containing the crosslinking agent (E), the hardness of the resist underlayer film can be increased. The crosslinking agent (E) can be used alone or in combination of two or more.

[0121] Examples of the crosslinking agent include polyfunctional (meth)acrylate compounds, epoxy compounds, hydroxymethyl group-substituted phenol compounds, alkoxyalkyl group-containing phenol compounds, compounds having an alkoxyalkylated amino group, and compounds represented by the following formulas (E1) to (E5) (hereinafter also referred to as "compounds (E1) to (E5)"):

[0122]

[0123] Examples of polyfunctional (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin tri(meth)acrylate, and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate. , ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, and the like.

[0124] Examples of the epoxy compound include novolac type epoxy resins, bisphenol type epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

[0125] Examples of hydroxymethyl-substituted phenol compounds include 2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene, and 3,5-dihydroxymethyl-4-methoxytoluene [2,6-bis(hydroxymethyl)-p-cresol].

[0126] Examples of alkoxyalkyl group-containing phenolic compounds include methoxymethyl group-containing phenolic compounds and ethoxymethyl group-containing phenolic compounds.

[0127] Examples of compounds having an alkoxyalkylated amino group include nitrogen-containing compounds having multiple active methylol groups in one molecule, such as (poly)methylolated melamine, (poly)methylolated glycoluril, (poly)methylolated benzoguanamine, and (poly)methylolated urea, in which at least one hydrogen atom of the hydroxyl group of the methylol group is substituted with an alkyl group such as a methyl group or a butyl group. The compound having an alkoxyalkylated amino group may be a mixture of multiple substituted compounds, or may contain an oligomer component formed by partial self-condensation.

[0128] When the composition for forming a resist underlayer film contains the crosslinking agent [E], the lower limit of the content of the crosslinking agent [E] is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 3 parts by mass, relative to 100 parts by mass of the compound [A]. The upper limit of the content is preferably 80 parts by mass, more preferably 50 parts by mass, even more preferably 30 parts by mass, and particularly preferably 20 parts by mass. By setting the content of the crosslinking agent [E] within the above range, the crosslinking reaction of the compound [A] can be more effectively induced.

[0129] [Oxidizing Agent (F)] The oxidizing agent (F) is a component that promotes crosslinking of the compound (A) through an oxidation reaction. When the composition contains an oxidizing agent, the crosslinking reaction of the compound (A) is promoted, and the heat resistance of the formed resist underlayer film can be further improved. The oxidizing agent (F) can be used alone or in combination of two or more.

[0130] [F] The oxidizing agent may be a known oxidizing agent. The oxidizing agent is preferably a diketone compound, such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 3,5-di-tert-butyl-1,2-benzoquinone, 2,3-butanedione, pyruvic acid, oxamide, oxamic acid, 2,3-pentanedione, 2-oxobutyric acid, methyl pyruvate, 1,2-cyclohexanedione, 3-methyl-1,2-cyclopentanedione, parabanic acid, 3,4-hexanedione, methyl 2-oxobutyrate, ethyl pyruvate, 2-oxovaleric acid, Ethyl oxamate, N,N-dimethyloxamic acid, dimethyl oxalate, 3,4-dimethyl-1,2-cyclopentanedione, 2,3-heptanedione, 5-methyl-2,3-hexanedione, 4-methyl-2-oxovaleric acid, 3-methyl-2-oxovaleric acid, 3,3-dimethyl-2-oxobutyric acid, methyl 2-oxovalerate, oxalacetic acid, 1-ethyl-2,3-dioxopiperazine, butyl oxamate, 2-oxoglutaric acid, diethyl oxalate, 1,2-indandione, isatin, 1-Phenyl-1,2-propanedione, Benzoylformic acid, Methyl trifluoropyruvate, Ethyl 2,4-dioxovalerate, 1,2-naphthoquinone, 1-methylisatin, Methyl benzoylformate, Phenylpyruvic acid, 2,3-bornanedione, Triquinoyl hydrate, Ethyl trifluoropyruvate, Diethyl mesooxalate, Dimethyl 2-oxoglutarate, Dimethyloxaloylglycine, N,N'-Dimethoxy-N,N'-dimethyloxamide, Ethyl benzoylformate, 4-Hydroxy Examples of the oxalic acid derivative include phenylpyruvic acid, diethyl oxalate, furil, 1,1'-oxalyldiimidazole, diethyl methyloxalate, dibutyl oxalate, 9,10-phenanthrenequinone, 1,10-phenanthroline-5,6-dione, benzyl, diethyl chlorooxalate, 1,3-diphenylpropanetrione, diphenyl oxalate, o-chloranil, 1,4-bisbenzyl, bis(2,4-dinitrophenyl) oxalate, and bis(2,4,6-trichlorophenyl) oxalate.

[0131] When the composition for forming a resist underlayer film contains the oxidizing agent [F], the lower limit of the content of the oxidizing agent [F] is preferably 0.01 parts by mass, more preferably 0.1 parts by mass, and even more preferably 0.5 parts by mass, relative to 100 parts by mass of the compound [A]. The upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass, and even more preferably 3 parts by mass. By setting the content of the oxidizing agent [F] within the above range, the crosslinking reaction of the compound [A] can be more effectively induced.

[0132] (Surfactant) The resist underlayer film-forming composition can improve its coatability by containing a surfactant, and as a result, the coating surface uniformity of the formed film can be improved and the occurrence of coating spots can be suppressed. The surfactant can be used alone or in combination of two or more.

[0133] Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate. Commercially available surfactants include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), F-Top EF101, EF204, EF303, EF352 (all manufactured by Tochem Products Co., Ltd.), Megafac F171, F172, F173 (all manufactured by DIC Corporation), Fluorad FC430, FC431, FC135, FC93 (all manufactured by Sumitomo 3M Limited), Asahiguard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 (all manufactured by Asahi Glass Co., Ltd.), and the like.

[0134] When the composition for forming a resist underlayer film contains a surfactant, the lower limit of the content of the surfactant is preferably 0.01 parts by mass, more preferably 0.05 parts by mass, and even more preferably 0.1 parts by mass, relative to 100 parts by mass of the compound [A]. The upper limit of the content is preferably 10 parts by mass, more preferably 5 parts by mass, and even more preferably 1 part by mass. By setting the content of the surfactant within the above range, the coatability of the composition for forming a resist underlayer film can be further improved.

[0135] (Other Polymers) Examples of other polymers that are additives include acrylic polymers containing only structural units having a phenolic hydroxyl group, acrylic polymers containing only structural units having an alcoholic hydroxyl group, and acrylic polymers containing structural units having an alcoholic hydroxyl group and structural units having a heterocyclic structure.

[0136] <Method for preparing a composition for forming a resist underlayer film> The composition for forming a resist underlayer film can be prepared by mixing [A] compound, [B] polymer, [C] solvent, and, if necessary, [D] acid generator, [E] crosslinking agent, [F] oxidizing agent, and other components in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter or the like having a pore size of about 0.5 μm. The lower limit of the solid content concentration of the composition for forming a resist underlayer film is preferably 0.1% by mass, more preferably 1% by mass, even more preferably 2% by mass, and particularly preferably 4% by mass. The upper limit of the solid content concentration is preferably 50% by mass, more preferably 30% by mass, even more preferably 15% by mass, and particularly preferably 8% by mass.

[0137] <<Method for Producing Semiconductor Substrate>> The method for producing a semiconductor substrate includes a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate (hereinafter also referred to as a “coating step”), a heating step of heating the coated film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume (hereinafter also referred to as a “heating step”), a step of directly or indirectly forming a resist pattern on the resist underlayer film formed by the coating step and the heating 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”).

[0138] The resist underlayer film-forming composition contains a compound having an aromatic ring, a polymer that thermally decomposes at least at the heating temperature in the heating step (excluding the case where the compound has an aromatic ring), and a solvent, wherein the molecular weight of the compound having an aromatic ring is 400 or more, and the content of the polymer in the resist underlayer film-forming composition is less than the content of the compound having an aromatic ring. As such a resist underlayer film-forming composition, the resist underlayer film-forming composition used in the method for forming a resist underlayer film can be suitably used.

[0139] According to the method for producing a semiconductor substrate, by using the composition for forming a resist underlayer film used in the method for forming a resist underlayer film in the coating step, a resist underlayer film having excellent heat resistance and flatness can be formed, and therefore a semiconductor substrate having a good pattern shape can be produced.

[0140] 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").

[0141] [Coating Step] As this step, the coating step in the method for forming a resist underlayer film described above can be suitably adopted.

[0142] [Heating Step] As this step, the heating step in the method for forming a resist underlayer film described above can be suitably adopted.

[0143] [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.

[0144] 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).

[0145] 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.

[0146] 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.

[0147] 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.

[0148] [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.

[0149] 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.

[0150] 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.

[0151] Next, the resist film formed as above is exposed by selective irradiation with radiation. The radiation used for exposure can be appropriately selected depending on the type of radiation-sensitive acid generator used in the resist composition, and examples thereof include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, electron beams, molecular beams, and particle beams such as ion beams. Among these, far ultraviolet light is preferred, and KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ２ Excimer laser light (wavelength 157 nm), Kr ２ Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm) or extreme ultraviolet light (wavelength 13.5 nm or the like, hereinafter also referred to as "EUV") is more preferred, and KrF excimer laser light, ArF excimer laser light or EUV is even more preferred.

[0152] 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.

[0153] 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.

[0154] After development with the developer, the resist is washed and dried to form a desired resist pattern.

[0155] [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.

[0156] Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the mask pattern, the elemental composition of the film to be etched, etc., and can be, for example, CHF ３ , C.F. ４ , C ２ F ６ , C ３ F ８ , SF ６ Fluorine-based gases such as Cl ２ , BCl３ 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, NH ３ , BCl ３ reducing gases such as He, N ２ and inert gases such as Ar. These gases may be used in combination. When etching a substrate using the pattern of the resist underlayer film as a mask, a fluorine-based gas is usually used.

[0157] <<Composition for Forming a Resist Underlayer Film>> The composition for forming a resist underlayer film is used in a method for forming a resist underlayer film, which includes a step of directly or indirectly applying the composition for forming a resist underlayer film to a substrate and a heating step of heating the coating film obtained by the coating step at a temperature higher than 450°C and lower than 600°C in an atmosphere with an oxygen concentration of less than 0.01% by volume. The composition contains a compound having an aromatic ring, a polymer that thermally decomposes at least at the heating temperature in the heating step (excluding the case where the compound having an aromatic ring is the polymer), and a solvent, wherein the molecular weight of the compound having an aromatic ring is 400 or more, and the content of the polymer is lower than the content of the compound having an aromatic ring. The composition for forming a resist underlayer film used in the method for forming a resist underlayer film can be suitably used as the composition for forming a resist underlayer film. The composition for forming a resist underlayer film can form a resist underlayer film with excellent heat resistance and flatness.

[0158] <<Resist Underlayer Film>> The resist underlayer film is formed from the composition for forming a resist underlayer film. The resist underlayer film formed from the composition for forming a resist underlayer film has excellent heat resistance and flatness.

[0159] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0160] [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.

[0161] [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 using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D") and calculating the average value of the film thicknesses.

[0162] <Synthesis of Compound [A]> Compounds or polymers represented by the following formulas (A-1) to (A-9) and (A-11) to (A-31) (hereinafter also referred to as "compounds or polymers (A-1) to (A-9) and (A-11) to (A-31)") were synthesized as compound [A] by the procedure shown below. A ready-made product was used as the compound represented by the following formula (A-9) (compound (A-9)). Polymer (A-10) was a polymer having a structural unit derived from compound (A-9).

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169] In the above formulas (A-1), (A-4) and (A-8), the numbers attached to each structural unit indicate the content (mol %) of that structural unit. Ｒ indicates the bonding site to the oxygen atom.

[0170] Synthesis Example 1-1 Synthesis of Polymer (A-1) In a nitrogen atmosphere, 70 g of m-cresol, 57.27 g of p-cresol, 95.52 g of a 37% by mass aqueous formaldehyde solution, and 381.82 g of methyl isobutyl ketone were added to a reaction vessel and dissolved. The resulting solution was heated to 40°C, and then 2.03 g of p-toluenesulfonic acid was added and reacted at 85°C for 4 hours. The reaction solution was cooled to 30°C or below, and then poured into a mixed solution of methanol / water (50 / 50 (mass ratio)) to cause reprecipitation. The precipitate was collected using filter paper and dried to obtain Polymer (A-1). The Mw of Polymer (A-1) was 5,000.

[0171] Synthesis Example 1-2 Synthesis of Polymer (A-2) In a nitrogen atmosphere, 150 g of 2,7-dihydroxynaphthalene, 76.01 g of a 37% by mass aqueous formaldehyde solution, and 450 g of methyl isobutyl ketone were added to a reaction vessel and dissolved. The resulting solution was heated to 40°C, and then 1.61 g of p-toluenesulfonic acid was added, followed by reaction at 80°C for 7 hours. The reaction liquid was cooled to 30°C or below, and then poured into a mixed solution of methanol / water (50 / 50 (mass ratio)) to cause reprecipitation. The precipitate was collected using filter paper and dried to obtain Polymer (A-2). The Mw of Polymer (A-2) was 3,000.

[0172] Synthesis Example 1-3 Synthesis of Polymer (A-3) 20 g of 1-hydroxypyrene, 7.16 g of 2-naphthaldehyde, and 82 g of propylene glycol monomethyl ether were charged into a reaction vessel under a nitrogen atmosphere and dissolved at room temperature. 8.81 g of methanesulfonic acid was added to the resulting solution, and the mixture was stirred at 120°C for 12 hours to polymerize. After completion of the polymerization, the polymerization reaction solution was poured into a large amount of a mixed solution of methanol / water (80 / 20 (mass ratio)), and the resulting precipitate was collected by filtration to obtain Polymer (A-3). The Mw of Polymer (A-3) was 1,100.

[0173] Synthesis Example 1-4 (Synthesis of Polymer (A-4)) A reaction vessel was charged with 15.2 g of 4,4'-(α-methylbenzylidene)bisphenol, 7.63 g of 1-hydroxypyrene, 12.6 g of 1-naphthol, and 4.52 g of paraformaldehyde under a nitrogen atmosphere. Next, 60 g of propylene glycol monomethyl ether acetate was added and dissolved, and then 0.220 g of p-toluenesulfonic acid monohydrate was added, and the mixture was stirred at 95°C for 6 hours to polymerize. After completion of the polymerization, the polymerization reaction solution was poured into a large amount of a mixed solution of methanol / water (70 / 30 (mass ratio)), and the resulting precipitate was collected by filtration to obtain Polymer (A-4). The Mw of Polymer (A-4) was 3,363.

[0174] [Synthesis Example 1-5] (Synthesis of Polymer (A-5)) Polymer (A-5) was obtained in the same manner as in Synthesis Example 1-4, except that 15.12 g of 4,4'-(α-methylbenzylidene)bisphenol, 7.63 g of 1-hydroxypyrene, 12.6 g of 1-naphthol, and 4.52 g of paraformaldehyde in Synthesis Example 1-4 were changed to 37.9 g of bisphenolfluorene and 2.86 g of paraformaldehyde. The Mw of polymer (A-5) was 4,500.

[0175] Synthesis Example 1-6 (Synthesis of Polymer (A-6)) In a nitrogen atmosphere, 20 g of Polymer (A-2) synthesized in Synthesis Example 1-2, 80 g of N,N-dimethylacetamide, and 22 g of potassium carbonate were charged into a reaction vessel. Next, the mixture was heated to 80°C, and 19 g of propargyl bromide was added, followed by stirring for 6 hours to carry out the reaction. Thereafter, 40 g of methyl isobutyl ketone and 80 g of water were added to the reaction solution, followed by a separation operation. The resulting organic phase was then poured into a large amount of methanol, and the resulting precipitate was collected by filtration to obtain Polymer (A-6). The Mw of Polymer (A-6) was 3,200.

[0176] Synthesis Example 1-7 (Synthesis of Polymer (A-7)) In a nitrogen atmosphere, 20 g of Polymer (A-5) synthesized in Synthesis Example 1-5, 80 g of N,N-dimethylacetamide, and 22 g of potassium carbonate were charged into a reaction vessel. Next, the mixture was heated to 80°C, and 19 g of propargyl bromide was added, followed by stirring for 6 hours to carry out the reaction. Thereafter, 40 g of methyl isobutyl ketone and 80 g of water were added to the reaction solution, followed by a separation operation. The resulting organic phase was then poured into a large amount of methanol, and the resulting precipitate was collected by filtration to obtain Polymer (A-7). The Mw of Polymer (A-7) was 4,800.

[0177] Synthesis Example 1-8 (Synthesis of Polymer (A-8)) In a nitrogen atmosphere, 20 g of Polymer (A-4) synthesized in Synthesis Example 1-4 and 18.9 g of potassium carbonate were charged into a reaction vessel. Next, the mixture was heated to 80°C, and 35.3 g of propargyl bromide was added, followed by stirring for 6 hours to carry out the reaction. Thereafter, 40 g of methyl isobutyl ketone and 80 g of water were added to the reaction solution, followed by a separation operation. The resulting organic phase was then poured into a large amount of methanol, and the resulting precipitate was collected by filtration to obtain Polymer (A-8). The Mw of Polymer (A-8) was 3,820.

[0178] Synthesis Example 1-9 (Synthesis of Polymer (A-10)) 50.0 g of compound (A-9) was dissolved in 200 g of methyl isobutyl ketone. The resulting solution was heated to 40°C, and then 0.69 g of p-toluenesulfonic acid was added, followed by reaction at 100°C for 6 hours. The reaction solution was cooled to 30°C or below, and 300 g of propylene glycol monomethyl ether acetate was added. The methyl isobutyl ketone was removed by concentration under reduced pressure, yielding a propylene glycol monomethyl ether acetate solution of polymer (A-10). The Mw of polymer (A-10) was 2,400.

[0179] Synthesis Example 1-10 (Synthesis of Polymer (A-11)) 1.60 g of 2,6-naphthalenediol, 1.82 g of 4-biphenylaldehyde, and 30 ml of methyl isobutyl ketone were charged, and 5 ml of 95% sulfuric acid was added, followed by a reaction at 100°C for 6 hours. Next, the reaction solution was concentrated, and 50 g of pure water was added to precipitate the reaction product. After cooling to room temperature, the reaction product was separated by filtration. The resulting solid was filtered and dried, and then separated and purified by column chromatography. 10 g of this compound, 0.7 g of paraformaldehyde, 50 ml of glacial acetic acid, and 50 ml of propylene glycol monomethyl ether (PGME) were charged, and 8 ml of 95% sulfuric acid was added, followed by a reaction at 100°C for 6 hours. Next, the reaction solution was concentrated, and 1000 ml of methanol was added to precipitate the reaction product. After cooling to room temperature, the reaction product was separated by filtration. The resulting solid was filtered, dried, and then separated and purified by column chromatography to obtain polymer (A-11). The Mw of polymer (A-11) was 1,793.

[0180] Synthesis Example 1-11 (Synthesis of Polymer (A-12)) 30 g of coronene and 19 g of 2-naphthoyl chloride were dissolved in a flask containing 170 g of dichloroethane. After 15 minutes, 16 g of aluminum trichloride was gradually added, and the mixture was allowed to react at room temperature for 4 hours. After the reaction was completed, aluminum trichloride was removed using water, and the mixture was concentrated using an evaporator to obtain the following compound (a-12). Next, 11.7 g of 1H-indole, 45.5 g of the compound (a-12), 9.5 g of p-toluenesulfonic acid monohydrate, and 82 g of 1,4-dioxane were added to the flask, and the mixture was stirred at 100°C. After the reaction was completed, 100 g of hexane was added to extract the 1,4-dioxane, and the precipitate formed by adding methanol was filtered. The remaining monomer was removed using methanol to obtain Polymer (A-12). The Mw of Polymer (A-12) was 2,900.

[0181]

[0182] Synthesis Example 1-12 (Synthesis of Compound (A-13)) 4-Hydroxyindole (30 mmol), hydroxypyrene-1-carbaldehyde (30 mmol), and tetramethylguanidine (6 mmol) were placed in a mixture, and 60 ml of distilled water was added as a solvent. The reaction mixture was stirred at room temperature (25°C) for 24 hours. After the reaction was completed, the mixture was subjected to liquid separation and extraction using distilled water and ethyl acetate, and the organic layer was recovered. The recovered organic layer was dissolved in 40 g of propylene glycol monomethyl ether acetate, and p-toluenesulfonic acid (10 mol% based on the total reactants) was added, followed by stirring and heating at 60°C for 2 hours. After the reaction was completed, the mixture was subjected to liquid separation and extraction using distilled water and ethyl acetate, and the organic layer was recovered. The organic layer was added dropwise to n-hexane (500 ml), and the mixture was precipitated, filtered, and dried to obtain compound (A-13).

[0183] Synthesis Example 1-13 (Synthesis of Polymer (A-14)) 9-fluorenone (200 parts by mass), 9,9-bis(4-hydroxyphenyl)fluorene (2,333 parts by mass), and dichloromethane (10,430 parts by mass) were added to a reactor, and the mixture was heated to 40°C with stirring under a nitrogen atmosphere and maintained at that temperature. Subsequently, trifluoromethanesulfonic acid (92 parts by mass) and 3-mercaptopropionic acid (6 parts by mass) dissolved in dichloromethane (200 parts by mass) were slowly added to the reactor, and the mixture was reacted at 40°C for 2 minutes with stirring. After completion of the reaction, the reaction solution was cooled to room temperature. Sufficient water was added to the reaction solution, and excess 9,9-bis(4-hydroxyphenyl)fluorenone was removed by filtration. The precipitate was washed with dichloromethane. Sufficient water was added to the dichloromethane solution to remove trifluoromethanesulfonic acid. Subsequently, the dichloromethane was removed, and a precursor was obtained. A precursor (200 parts by mass), potassium carbonate (323 parts by mass), and acetone (616 parts by mass) were added to a reactor and maintained at 56°C while stirring under a nitrogen atmosphere. Then, 3-bromo-1-propyne (278 parts by mass) was added to the reactor, and the mixture was allowed to react for 3 hours while stirring at 56°C. After completion of the reaction, the reaction solution was cooled to normal room temperature. Excess potassium carbonate and its salt were removed by filtration. The precipitate was washed with acetone to obtain a dry solid. The obtained dry solid was dissolved in ethyl acetate (820 parts by mass). Sufficient water was added to the ethyl acetate solution to remove metal impurities. The ethyl acetate was removed to obtain a dry solid. This dry solid (185 parts by mass) was dissolved in acetone (185 parts by mass). Methanol (1,850 parts by mass) was then added to the acetone solution, and the mixture was filtered to obtain a solid. The solid was dried to obtain Polymer (A-14). The Mw of Polymer (A-14) was 1,600.

[0184] Synthesis Example 1-14 Synthesis of Compound (A-15) 50.0 g of 3,6,11,14-tetrahydroxydibenzochrysene, 25.5 g of sodium hydroxide, and 200 g of water were prepared into a homogeneous solution at 40°C under a nitrogen atmosphere. 61.2 g of 37% formalin was added dropwise over 1 hour, and the mixture was stirred at 40°C for 8 hours. 800 g of methyl isobutyl ketone was added, and then 120 g of 20% aqueous hydrochloric acid was added while cooling in an ice bath to terminate the reaction. After filtering off the insoluble matter, the aqueous layer was removed, and the organic layer was washed five times with 200 g of pure water. The organic layer was evaporated to dryness under reduced pressure, dissolved in 250 g of tetrahydrofuran, and then poured into diisopropyl ether to cause reprecipitation. The precipitate was filtered off, washed twice with 200 g of diisopropyl ether, and then dried in vacuo at 50°C. 20.0 g of this compound and 121.6 g of methanol were made into a homogeneous solution at 50°C under a nitrogen atmosphere, and then 6.2 g of a 10 wt% methanol solution of sulfuric acid was slowly added dropwise and stirred under reflux for 8 hours. After cooling to room temperature, 300 g of methyl isobutyl ketone and 100 g of pure water were added. After filtering off the insoluble matter, the aqueous layer was removed and the organic layer was washed five times with 200 g of pure water. The organic layer was evaporated to dryness under reduced pressure, then dissolved in 60 g of toluene and poured into hexane to cause reprecipitation. The precipitate was filtered off, washed twice with 100 g of hexane, and then vacuum dried at 50°C to obtain compound (A-15).

[0185] Synthesis Example 1-15 Synthesis of Compound (A-16) 39.2 g of 3,6,11,14-tetrahydroxydibenzochrysene, 66.9 g of potassium carbonate, and 180 g of dimethylformamide were stirred under a nitrogen atmosphere at 50°C, while 52.3 g of propargyl bromide was added dropwise over 40 minutes. After the dropwise addition was completed, stirring was continued at 50°C for 24 hours. Thereafter, 500 g of methyl isobutyl ketone and 100 g of pure water were added. After filtering off the insoluble matter, the aqueous layer was removed, and then the organic layer was washed four times with 100 g of pure water. The organic layer was dried under reduced pressure, dissolved in 150 g of toluene, and then poured into methanol to cause reprecipitation. The precipitate was filtered off, washed twice with 200 g of methanol, and then vacuum dried at 50°C to obtain compound (A-16).

[0186] Synthesis Example 1-16 (Synthesis of Compound (a-17)) In a nitrogen atmosphere, 20.0 g of 2-acetylfluorene and 20.0 g of m-xylene were placed in a reaction vessel and dissolved at 110°C. Next, 3.14 g of dodecylbenzenesulfonic acid was added, and the mixture was heated to 140°C and reacted for 16 hours. After completion of the reaction, 80 g of xylene was added to dilute the reaction solution, and then the mixture was cooled to 50°C and poured into 500 g of methanol to cause reprecipitation. The obtained precipitate was washed with toluene, and the solid was collected with filter paper and dried to obtain a compound represented by the following formula (a-17) (hereinafter also referred to as "compound (a-17)").

[0187]

[0188] Synthesis Example 1-17 Synthesis of Compound (A-17) 10.0 g of the compound (a-17), 7.2 g of p-ethynylbenzaldehyde, and 40 g of toluene were added to a reaction vessel under a nitrogen atmosphere and stirred. After that, 25.2 g of a 50% by mass aqueous sodium hydroxide solution and 1.7 g of tetrabutylammonium bromide were added, and the mixture was reacted at room temperature for 6 hours. After the reaction, 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous oxalic acid solution was added and subjected to liquid separation and extraction, and then the mixture was poured into hexane to cause reprecipitation. The precipitate was collected by filtration to obtain compound (A-17).

[0189] Synthesis Example 1-18 Synthesis of Polymer (A-18) 120 g of N-methyl-2-pyrrolidone was added to 15.55 g of 4,4-(hexafluoroisopropylidene)diphthalic anhydride and 14.62 g of 1,3-bis(3-aminophenoxy)benzene, and the mixture was allowed to react for 3 hours at 40°C under a nitrogen atmosphere. 5.16 g of 4-ethynylphthalic anhydride was added to the resulting compound, and the mixture was allowed to react for an additional 3 hours at 40°C. 4.00 g of pyridine was added to the resulting reaction solution, and 12.25 g of acetic anhydride was added dropwise, followed by a reaction at 60°C for 4 hours. After completion of the reaction, the mixture was cooled to room temperature, and 400 g of methyl isobutyl ketone was added. The organic layer was washed twice with 100 g of a 3% aqueous nitric acid solution and then six times with 100 g of pure water, and the organic layer was evaporated to dryness under reduced pressure. 100 g of tetrahydrofuran (THF) was added, and the mixture was poured into methanol to cause reprecipitation. The precipitate was filtered off, washed twice with 300 g of methanol, and then vacuum dried at 70° C. to obtain polymer (A-18). The Mw of polymer (A-18) was 4,320.

[0190] Synthesis Example 1-19 (Synthesis of Polymer (A-19)) Under a nitrogen atmosphere, 200 g of 1,2-dichloroethane and 13.1 g of methanesulfonic acid were slowly added to 30.0 g of 9-propargyl-9-fluorenol, and the mixture was reacted at 70°C for 8 hours. After cooling to room temperature, 500 g of toluene was added, and the mixture was washed six times with 100 g of pure water, and the organic layer was evaporated to dryness under reduced pressure. 100 g of THF was added, and the mixture was poured into methanol to cause reprecipitation. The precipitate was filtered, washed twice with 200 g of methanol, and then vacuum dried at 70°C to obtain Polymer (A-19). The Mw of Polymer (A-19) was 2,450.

[0191] Synthesis Example 1-20 (Synthesis of Compound (A-20)) 120 g of N-methyl-2-pyrrolidone was added to 7.91 g of 1,5-diaminonaphthalene and 17.21 g of 4-ethynylphthalic anhydride, and the mixture was allowed to react for 3 hours at 40°C under a nitrogen atmosphere. 3.96 g of pyridine was added thereto, and 12.26 g of acetic anhydride was then slowly added dropwise thereto, followed by a reaction at 60°C for 4 hours. After completion of the reaction, the mixture was cooled to room temperature, and 300 g of methyl isobutyl ketone was added. The organic layer was washed with 100 g of a 3% aqueous nitric acid solution, and then washed five times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 100 g of THF was added, and the mixture was poured into methanol to cause reprecipitation. The precipitate was filtered, washed twice with 200 g of methanol, and then dried in vacuo at 70°C to obtain Compound (A-20).

[0192] Synthesis Example 1-21 (Synthesis of Compound (A-21)) 100 g of N-methyl-2-pyrrolidone was added to 32.13 g of 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and 9.31 g of aniline previously dissolved in 30 g of N-methyl-2-pyrrolidone was slowly added dropwise under a nitrogen atmosphere, followed by a reaction at 40°C for 3 hours. 130 g of o-xylene was added thereto, and the reaction was carried out for 9 hours at 180°C while removing water generated from the system. After completion of the reaction, the mixture was cooled to room temperature and poured into methanol to cause reprecipitation. The precipitate was filtered, washed twice with 300 g of methanol, and then vacuum dried at 70°C to obtain Compound (A-21).

[0193] Synthesis Example 1-22 (Synthesis of Compound (A-22)) 1.8 g of a compound represented by the following formula (X-1), 82.0 g of a compound represented by the following formula (x-2), 5 mL of β-mercaptopropionic acid, and 200 mL of 1,2-dichloroethane were prepared into a homogeneous solution at a liquid temperature of 60°C under a nitrogen atmosphere, and 10 mL of methanesulfonic acid was slowly added thereto, followed by stirring at a liquid temperature of 70°C for 12 hours. After cooling to room temperature, 400 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 1,000 g of pure water, and then the organic layer was evaporated to dryness under reduced pressure. 200 g of tetrahydrofuran (THF) was added to the residue to prepare a homogeneous solution, which was then crystallized in 1,000 g of hexane. The crystallized crystals were filtered using a Kiriyama funnel and washed twice with 300 mL of hexane. The crystals were then recovered and dried at 60°C in vacuo to obtain compound (A-22).

[0194]

[0195] Synthesis Example 1-23 Synthesis of Compound (A-23) 15.0 g of trichlorotriazine, 28.6 g of 3-ethynylaniline, and 130.8 g of toluene were placed in a reaction vessel under a nitrogen atmosphere and reacted at 0° C. for 1 hour, followed by a reaction at 110° C. for 3 hours to obtain the compound (A-23).

[0196] Synthesis Example 1-24 (Synthesis of Polymer (A-24)) A reaction vessel was charged with 10.0 g of 4,4'-(α-methylbenzylidene)bisphenol and 6.28 g of 4-biphenylaldehyde under a nitrogen atmosphere. Next, 47 g of 1-butanol was added and dissolved, and then 3.28 g of p-toluenesulfonic acid monohydrate was added, and the mixture was stirred at 110°C for 6 hours to polymerize. After completion of the polymerization, the polymerization reaction solution was poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain Polymer (A-24). The Mw of Polymer (A-24) was 4,600.

[0197] Synthesis Example 1-25 Synthesis of Compound (A-25) In a reaction vessel under a nitrogen atmosphere, 10.0 g of the compound (a-17), 9.9 g of 1-naphthaldehyde, and 50 g of toluene were added and stirred, and then 25.2 g of a 50% by mass aqueous sodium hydroxide solution and 1.7 g of tetrabutylammonium bromide were added, and the mixture was reacted at 92°C for 12 hours. The reaction liquid was cooled to 50°C, and then 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous oxalic acid solution was added to perform separation and extraction, and then the mixture was poured into a large amount of hexane, and the resulting precipitate was collected by filtration, thereby obtaining compound (A-25).

[0198] Synthesis Example 1-26 Synthesis of Polymer (a-26) 10.0 g of fluorene, 10.8 g of 9-fluorenone, and 62.5 g of chlorobenzene were added to a reaction vessel under a nitrogen atmosphere and stirred, and then 5.9 g of methanesulfonic acid was slowly added and the mixture was reacted at 120°C for 8 hours. The reaction solution was cooled to 50°C and washed five times with 100 g of pure water. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain polymer (a-26) represented by the following formula (a-26). The Mw of polymer (a-26) was 2,100.

[0199]

[0200] Synthesis Example 1-27 Synthesis of Compound (A-26) 10.0 g of the polymer (a-26), 7.1 g of 2-naphthaldehyde, and 50 g of toluene were placed in a reaction vessel under a nitrogen atmosphere and stirred. After that, 7.3 g of a 50% by mass aqueous solution of sodium hydroxide and 2.9 g of tetrabutylammonium bromide were added, and the mixture was reacted at 92°C for 12 hours. The reaction solution was cooled to 50°C, and 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous solution of oxalic acid was added to perform separation and extraction. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain polymer (A-26). The Mw of polymer (A-26) was 3,100.

[0201] [Synthesis Example 1-28] (Synthesis of Polymer (A-27)) Polymer (A-27) was obtained in the same manner as in Synthesis Example 1-27, except that 7.1 g of 2-naphthaldehyde was changed to 5.9 g of 3-ethynylbenzaldehyde. The Mw of polymer (A-27) was 3,000.

[0202] Synthesis Example 1-29 Synthesis of Polymer (A-28) Polymer (A-28) was obtained in the same manner as in Synthesis Example 1-27, except that 7.1 g of 2-naphthaldehyde was changed to 5.1 g of 2-thiophenecarboxaldehyde. The Mw of polymer (A-28) was 2,800.

[0203] Synthesis Example 1-30 Synthesis of Polymer (a-29) 10.0 g of fluorene, 14.1 g of 2-naphthaldehyde, and 48.2 g of chlorobenzene were added to a reaction vessel under a nitrogen atmosphere and stirred, and then 17.3 g of methanesulfonic acid was slowly added and the mixture was reacted at 120°C for 8 hours. The reaction solution was cooled to 50°C and washed five times with 100 g of pure water. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain polymer (a-29) represented by the following formula (a-29). The Mw of polymer (a-29) was 1,800.

[0204]

[0205] Synthesis Example 1-31 Synthesis of Polymer (A-29) 10.0 g of the polymer (a-29), 7.7 g of 2-naphthaldehyde, and 50 g of toluene were placed in a reaction vessel under a nitrogen atmosphere and stirred. After that, 7.9 g of a 50% by mass aqueous sodium hydroxide solution and 3.2 g of tetrabutylammonium bromide were added, and the mixture was reacted at 92°C for 12 hours. The reaction solution was cooled to 50°C, and 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous oxalic acid solution was added to perform liquid separation and extraction. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain Polymer (A-29). The Mw of Polymer (A-29) was 2,500.

[0206] Synthesis Example 1-32 Synthesis of Polymer (a-30) 10.0 g of fluorene, 11.1 g of acenaphthaquinone, and 62.9 g of chlorobenzene were added to a reaction vessel under a nitrogen atmosphere and stirred, and then 5.8 g of methanesulfonic acid was slowly added and the mixture was reacted at 120°C for 8 hours. The reaction solution was cooled to 50°C and washed five times with 100 g of pure water. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain polymer (a-30) represented by the following formula (a-30). The Mw of polymer (a-30) was 2,200.

[0207]

[0208] Synthesis Example 1-33 Synthesis of Polymer (A-30) 10.0 g of the polymer (a-30), 7.1 g of 2-naphthaldehyde, and 50 g of toluene were placed in a reaction vessel under a nitrogen atmosphere and stirred. After that, 7.3 g of a 50% by mass aqueous solution of sodium hydroxide and 2.9 g of tetrabutylammonium bromide were added, and the mixture was reacted at 92°C for 12 hours. The reaction solution was cooled to 50°C, and 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous solution of oxalic acid was added to perform liquid separation and extraction. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain polymer (A-30). The Mw of polymer (A-30) was 3,000.

[0209] Synthesis Example 1-34 Synthesis of Polymer (a-31) After 10.0 g of fluorene and 200.0 g of dichloromethane were added to a reaction vessel under a nitrogen atmosphere, a mixed solution of 97.6 g of iron (III) chloride and 150.0 g of nitromethane was added dropwise, and the mixture was reacted at room temperature for 50 hours. The precipitate was collected with filter paper, washed with 300.0 g of nitromethane, and dried to obtain polymer (a-31) represented by the following formula (a-31). The Mw of polymer (a-31) was 1,400.

[0210] Synthesis Example 1-35 Synthesis of Polymer (A-31) In a nitrogen atmosphere, 10.0 g of the polymer (a-31), 14.3 g of 2-naphthaldehyde, and 50 g of toluene were placed in a reaction vessel and stirred. After that, 14.6 g of a 50% by mass aqueous solution of sodium hydroxide and 5.9 g of tetrabutylammonium bromide were added, and the mixture was reacted at 92°C for 12 hours. The reaction solution was cooled to 50°C, and 25 g of tetrahydrofuran was added. After removing the aqueous phase, 50 g of a 1% by mass aqueous solution of oxalic acid was added to perform separation and extraction. The mixture was then poured into a large amount of hexane, and the resulting precipitate was collected by filtration to obtain Polymer (A-31). The Mw of Polymer (A-31) was 2,100.

[0211] <Synthesis of Polymer [B]> As the polymer [B], polymers represented by the following formulas (B-1) to (B-16) (hereinafter also referred to as "polymers (B-1) to (B-16)") were synthesized by the procedure shown below.

[0212]

[0213]

[0214] In the above formulas (B-1) to (B-16), the number attached to each structural unit indicates the content (mol %) of that structural unit.

[0215] Synthesis Example 2-1 (Synthesis of Polymer (B-1)) 43.0 g of 1,1,1,3,3,3-hexafluoroisopropyl methacrylate and 57.0 g of vinylbenzyl alcohol were dissolved in 130 g of methyl isobutyl ketone, and 19.6 g of 2,2'-azobis(2-methylpropionate)dimethyl was added to prepare a monomer solution. 70 g of methyl isobutyl ketone was placed in a reaction vessel under a nitrogen atmosphere, and the mixture was heated to 80°C. While stirring, the monomer solution was added dropwise over 3 hours. The start of the dropwise addition marked the start of the polymerization reaction. After the polymerization reaction was carried out for 6 hours, the mixture was cooled to 30°C or below. 300 g of propylene glycol monomethyl ether acetate was added to the reaction solution, and the methyl isobutyl ketone was removed by concentration under reduced pressure, yielding a propylene glycol monomethyl ether acetate solution of polymer (B-1). The Mw of polymer (B-1) was 4,200.

[0216] Synthesis Examples 2-2 to 2-12 (Synthesis of Polymers (B-2) to (B-12)) Solutions of polymers (B-2) to (B-12) in propylene glycol monomethyl ether acetate were obtained in the same manner as in Synthesis Example 2-1, except that monomers giving the structural units represented by the above formulae (B-2) to (B-12) at the respective content ratios (mol %) were used. The Mw of polymer (B-2) was 3,800, the Mw of polymer (B-3) was 4,000, the Mw of polymer (B-4) was 4,300, the Mw of polymer (B-5) was 4,500, the Mw of polymer (B-6) was 4,100, the Mw of polymer (B-7) was 4,100, the Mw of polymer (B-8) was 4,200, the Mw of polymer (B-9) was 4,200, the Mw of polymer (B-10) was 4,300, the Mw of polymer (B-11) was 4,100, and the Mw of polymer (B-12) was 4,400.

[0217] Synthesis Example 2-13 (Synthesis of Polymer (B-13)) 100.0 g of 3,4-dihydroxyphenyl methacrylate was dissolved in 130 g of methyl ethyl ketone, and 16.6 g of 2,2'-azobis(2-methylpropionate)dimethyl was added to prepare a monomer solution. 70 g of methyl ethyl ketone was placed in a reaction vessel under a nitrogen atmosphere, and the mixture was heated to 78°C. While stirring, the monomer solution was added dropwise over 3 hours. The start of the dropwise addition marked the start of the polymerization reaction. After the polymerization reaction was carried out for 6 hours, the mixture was cooled to 30°C or below. 300 g of propylene glycol monomethyl ether acetate was added to the reaction solution, and the methyl ethyl ketone was removed by concentration under reduced pressure, yielding a propylene glycol monomethyl ether acetate solution of polymer (B-13). The Mw of polymer (B-13) was 4,200.

[0218] [Synthesis Example 2-14] (Synthesis of Polymer (B-14)) A propylene glycol monomethyl ether acetate solution of Polymer (B-14) was obtained in the same manner as in Synthesis Example 1-12, except that 4-hydroxyphenyl methacrylate was used instead of 3,4-dihydroxyphenyl methacrylate. The Mw of Polymer (B-14) was 3,900.

[0219] Synthesis Example 2-15 (Synthesis of Polymer (B-15)) A solution of 5.50 g of glycerin monomethacrylate, 5.09 g of 5-vinylbenzo[d][1,3]dioxole, 0.66 g of 2,2'-azobis(isobutyronitrile), and 35.99 g of propylene glycol monomethyl ether acetate was added to a dropping funnel, and the mixture was added dropwise to a reaction flask containing 9.00 g of propylene glycol monomethyl ether acetate at 100°C under a nitrogen atmosphere, followed by heating and stirring for 20 hours. To the resulting solution, 11 g of a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and 11 g of an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added, and the mixture was subjected to ion exchange treatment at room temperature for 4 hours. The ion exchange resin was separated to obtain a propylene glycol monomethyl ether acetate solution of polymer (B-15). The Mw of the polymer (B-15) was 9,000.

[0220] Synthesis Example 2-16 (Synthesis of Polymer (B-16)) 23.3 g of propylene glycol monomethyl ether acetate was heated and stirred at 80°C under a nitrogen atmosphere. To this was added simultaneously and separately a mixture of 28.5 g of N-(butoxymethyl)acrylamide, 12.0 g of 2-phenoxyethyl acrylate, 12.9 g of tricyclodecanyl acrylate, and 46.7 g of propylene glycol monomethyl ether acetate, and a mixture of 4.45 g of dimethyl 2,2-azobis(2-methylpropionate) and 46.7 g of PGMEA over a period of 2 hours. After heating and stirring for an additional 16 hours, the mixture was cooled to 60°C, and 200 g of heptane was added. The mixture was then cooled to room temperature and allowed to stand for 2 hours. The upper layer was separated and removed, and 100 g of PGMEA was added. The heptane was then distilled off under reduced pressure to obtain a propylene glycol monomethyl ether acetate solution of polymer (B-16). The Mw of the polymer (B-16) was 8,000.

[0221] <Preparation of Composition> The solvent [C], the acid generator [D], the crosslinking agent [E], and the oxidizing agent [F] used in the preparation of the composition are shown below.

[0222] [[C] Solvent] C-1: Propylene glycol monomethyl ether acetate C-2: 1,6-diacetoxyhexane C-3: γ-butyrolactone C-4: Diethylene glycol dibutyl ether

[0223] [[D] Acid Generator] D-1: bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate (compound represented by the following formula (D-1))

[0224]

[0225] D-2: A compound represented by the following formula (D-2)

[0226] D-3: A compound represented by the following formula (D-3):

[0227] D-4: A compound represented by the following formula (D-4):

[0228] [[E] Crosslinking Agent] E-1: A compound represented by the following formula (E-1):

[0229]

[0230] [[F] Oxidizing agent] F-1: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

[0231] Example 1 100 parts by mass of (A-1) as the [A] compound and 3 parts by mass of (B-1) as the [B] compound were dissolved in 1,170 parts by mass of propylene glycol monomethyl ether acetate (C-1), and 130 parts by mass of 1,6-diacetoxyhexane (C-2) was added. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0232] Examples 2 to 61 and Comparative Examples 1 to 34 Compositions (J-2) to (J-61) and (CJ-1) to (CJ-31) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 1 and 2 below were used. Note that compositions (J-1), (J-14), and (J-16) were used in Comparative Examples 32 to 34. In Tables 1 and 2, a "-" in the columns "[B] Polymer," "[D] Acid Generator," "[E] Crosslinking Agent," and "[F] Oxidizing Agent" indicates that the corresponding component was not used.

[0233] <Evaluation> The flatness and heat resistance of the compositions prepared above were evaluated according to the following procedures. The results are shown in Tables 1 and 2, respectively.

[0234] [Flatness] The composition prepared above was applied by spin coating using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") onto a silicon substrate 1 having a trench pattern of 150 nm deep and 10 μm wide, as shown in FIG. 1 . The substrate was then heated at 250°C for 60 seconds in an atmospheric environment, followed by cooling at 23°C for 60 seconds to form a resist underlayer coating film 2 having an average thickness of 300 nm in the non-trench patterned portion, thereby obtaining a silicon substrate with a resist underlayer coating film. The cross-sectional shape of the silicon substrate with the resist underlayer coating film was observed with a scanning electron microscope (Hitachi High-Technologies Corporation's "S-4800"), and the difference (ΔFT) between the height of the resist underlayer coating film 2 at a central portion b of the trench pattern and the height of a non-trench patterned portion a 5 μm from the edge of the trench pattern was used as an index of flatness. The flatness was evaluated as "A" (very good) when the ΔFT was less than 30 nm, "B" (good) when it was 30 nm or more and less than 40 nm, and "C" (poor) when it was 40 nm or more. The height difference shown in Figure 1 is exaggerated compared to the actual height. Considering that the flatness here is an evaluation of the flatness of the coating and that the flatness of the coating film is almost maintained even after the heating step, the flatness of the film before the heating step was evaluated.

[0235] [Heat Resistance] The resist underlayer film-coated substrates obtained above were measured for film thickness before heating (baking) using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"). Subsequently, a resist underlayer film was formed by heating (baking) at 500°C for 300 seconds under basic conditions in a nitrogen atmosphere. The film thickness of the resist underlayer film (film thickness after heating) was measured, and the film thickness reduction rate of the film thickness after heating relative to the film thickness before heating was calculated. Heat resistance was evaluated as "A" (very good) when the film thickness reduction rate was less than 10%, "B" (good) when it was 10% or more but less than 20%, and "C" (poor) when it was 20% or more. For Examples 1 to 61 and Comparative Examples 1 to 34, the oxygen concentration and heating temperature during heating of the resist underlayer coating film were as shown in Tables 1 and 2.

[0236]

[0237]

[0238] As can be seen from the results in Tables 1 and 2, the resist underlayer films formed in the Examples were superior in flatness and heat resistance to the resist underlayer films formed in the Comparative Examples.

[0239] According to the method for forming a resist underlayer film of the present invention, a resist underlayer film having excellent heat resistance and flatness can be formed. According to the method for producing a semiconductor substrate of the present invention, a resist underlayer film having excellent heat resistance and flatness can be formed, thereby making it possible to obtain a good semiconductor substrate. According to the composition for forming a resist underlayer film of the present invention, a resist underlayer film having excellent heat resistance and flatness can be formed. The resist underlayer film formed by the composition for forming a resist underlayer film of the present invention has excellent heat resistance and flatness. Therefore, these can be suitably used in the production of semiconductor devices, etc.

[0240] 1 Silicon substrate 2 Resist underlayer coating film

Claims

1. A process of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a heating step of heating the coating film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume; A composition for forming a resist underlayer film used in a method for forming a resist underlayer film, comprising: a compound having an aromatic ring; a polymer (excluding the compound having an aromatic ring) that is thermally decomposed at least at the heating temperature in the heating step; Solvent and Contains the molecular weight of the compound having an aromatic ring is 400 or more, The composition for forming a resist underlayer film, wherein the content of the polymer is less than the content of the compound having an aromatic ring.

2. A composition for forming a resist underlayer film as described in claim 1, wherein the polymer has a first structural unit represented by the following formula (B1): 【Chemical 1】 (In formula (B1), R 1 is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. R 2 is a monovalent organic group having 1 to 20 carbon atoms.)

3. A composition for forming a resist underlayer film described in claim 1 or 2, wherein the content of the polymer per 100 parts by mass of the compound having the aromatic ring is 0.1 parts by mass or more and 50 parts by mass or less.

4. a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a heating step of heating the coating film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume; Including, The composition for forming a resist underlayer film, a compound having an aromatic ring; a polymer (excluding the compound having an aromatic ring) that is thermally decomposed at least at the heating temperature in the heating step; Solvent and Contains the molecular weight of the compound having an aromatic ring is 400 or more, The method for forming a resist underlayer film, wherein the content of the polymer in the composition for forming a resist underlayer film is less than the content of the compound having an aromatic ring.

5. 5. The method for forming a resist underlayer film according to claim 4, wherein the polymer has a first structural unit represented by the following formula (B1): 【Chemistry 2】 (In formula (B1), R １ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ２ is a monovalent organic group having 1 to 20 carbon atoms.

6. 6. The method for forming a resist underlayer film according to claim 4, wherein the content of the polymer is 0.1 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the compound having an aromatic ring.

7. a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; a heating step of heating the coating film obtained by the coating step at a temperature higher than 450°C and not higher than 600°C in an atmosphere having an oxygen concentration of less than 0.01% by volume; a step of forming a resist pattern directly or indirectly on the resist underlayer film formed by the coating step and the heating step; a step of performing etching using the resist pattern as a mask; Including, The composition for forming a resist underlayer film, a compound having an aromatic ring; a polymer (excluding the compound having an aromatic ring) that is thermally decomposed at least at the heating temperature in the heating step; Solvent and Contains the molecular weight of the compound having an aromatic ring is 400 or more, A method for producing a semiconductor substrate, wherein the content of the polymer in the composition for forming a resist underlayer film is less than the content of the compound having an aromatic ring.

8. The method for producing a semiconductor substrate according to claim 7 , wherein the polymer has a first structural unit represented by the following formula (B1): 【Chemistry 3】 (In formula (B1), R １ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ２ is a monovalent organic group having 1 to 20 carbon atoms.

9. 9. The method for manufacturing a semiconductor substrate according to claim 7, wherein the content of the polymer is 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the compound having an aromatic ring.

10. Before forming the resist pattern, A step of forming a silicon-containing film directly or indirectly on the resist underlayer film. The method for manufacturing a semiconductor substrate according to claim 7 or 8, further comprising:

11. A resist underlayer film formed from the composition for forming a resist underlayer film according to claim 1 .

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