Composition for resist underlayer film formation

Abstract

The present application provides a composition for resist underlayer film formation which is coated on a substrate and then exhibits high reflowability by a process of heating it, can be coated flat on a substrate with a high difference in level, and can form a planarization film. The solution is a composition for resist underlayer film formation of the present application which comprises a copolymer having a repeating structural unit represented by formula (1) and / or a repeating unit represented by formula (2), and an organic solvent. (In formula (1) and formula (2), R 1 represents a functional group represented by formula (3), in which formula (3), Q1 and Q2 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, * represents a binding end with an oxygen atom, and in formula (2), X 1 represents an organic group having 1 to 50 carbon atoms, and i and j each independently represent 0 or 1.)

Description

TECHNICAL FIELD

[0001] The present application relates to a resist underlayer film forming composition for forming a planarization film for burying a step and becoming flat on a substrate having a step, and a method for manufacturing a planarized resist underlayer film using the same. BACKGROUND

[0002] In recent years, semiconductor integrated circuit devices are required to be able to be processed with a fine pattern design. In order to form a more fine resist pattern by an optical lithography technique, it is necessary to make the exposure wavelength shorter.

[0003] However, with the shortening of the exposure wavelength, the depth of focus decreases, and thus it is necessary to further improve the planarization of a film formed on a substrate. That is, in order to manufacture a semiconductor device having a fine pattern design, establishment of a planarization technique of a planarization film formed on a step substrate becomes particularly important.

[0004] Hitherto, as a method for forming a planarization film, a method for forming a resist underlayer film formed under a resist film by photocuring has been disclosed.

[0005] A resist underlayer film forming composition containing a polymer having an epoxy group, an oxetanyl group in a side chain and a photocationic polymerization initiator, or a resist underlayer film forming composition containing a polymer having an ethylenically unsaturated bond capable of radical polymerization and a photoradical polymerization initiator has been disclosed (see Patent Document 1).

[0006] Further, a resist underlayer film forming composition containing a silicon-based compound having a cationically polymerizable reactive group such as an epoxy group, a vinyl group, a photocationic polymerization initiator, and a photoradical polymerization initiator has been disclosed (see Patent Document 2).

[0007] Further, a method for manufacturing a semiconductor device using a resist underlayer film containing a polymer having a crosslinkable functional group such as a hydroxyl group in a side chain, a crosslinking agent, and a photoacid generator has been disclosed (see Patent Document 3).

[0008] Further, a resist underlayer film having an unsaturated bond in a main chain or a side chain has been disclosed, although it is not a photocrosslinkable resist underlayer film (see Patent Documents 4 and 5).

[0009] PRIOR ART DOCUMENTS

[0010] PATENT DOCUMENTS

[0011] Patent Document 1: International Publication No. 2006 / 115044 pamphlet

[0012] Patent Literature 2: International Publication No. 2007 / 066597

[0013] Patent Literature 3: International Publication No. 2008 / 047638

[0014] Patent Literature 4: International Publication No. 2009 / 008446

[0015] Patent Literature 5: Japanese Patent Application Laid-Open No. 2004-533637 SUMMARY

[0016] PROBLEMS TO BE SOLVED BY THE INVENTION

[0017] In the past, in the case where a composition for resist underlayer film formation containing, for example, a polymer having a functional group capable of thermal crosslinking such as a hydroxyl group, a crosslinking agent, and an acid catalyst (an acid generator) is used as a material capable of photocrosslinking, when the composition is heated in order to be filled in a concavo-convex pattern (for example, a hole, a trench structure) formed on a substrate, a crosslinking reaction proceeds and viscosity increase occurs, as a result, there is a problem that filling failure to the inside of a pattern occurs.

[0018] Further, in the case where the heating temperature for forming a resist underlayer film in the past is 180°C or higher, there is a problem that the composition for resist underlayer film formation is slowly thermally cured and has poor reflow properties.

[0019] Further, in general, in a composition for resist underlayer film formation containing a polymer having a reactive group capable of cationic polymerization such as an epoxy group and a vinyl group and an acid generator, since curing is performed by combining light irradiation with heating, it is time-consuming and laborious.

[0020] Further, in a photolithography process of semiconductor device production, the shape of a pattern edge collapses by reflection of exposure light to a resist layer from a substrate, a resist pattern of a desired shape cannot be formed, and this becomes a cause of variation in the size of a resist pattern and further causes failure in image resolution.

[0021] Therefore, an object of the present application is to provide a composition for resist underlayer film formation for forming a planarization film on a substrate, which is capable of forming a cured film having high filling properties to a pattern, not causing thermal shrinkage, good reflow properties, and a reflection effect.

[0022] METHOD FOR SOLVING THE PROBLEM

[0023] As a first aspect of the present application, a composition for resist underlayer film formation is provided, which contains a copolymer having a repeating structural unit represented by formula (1) and / or a repeating unit represented by formula (2), and an organic solvent.

[0024]

[0025] (in formula (1) and formula (2), R 1 represents a functional group represented by formula (3), in formula (3), Q1and Q2each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, * represents a binding end with an oxygen atom, in formula (2), X 1 represents an organic group having 1 to 50 carbon atoms, i and j each independently represent 0 or 1)

[0026] As the second aspect in the present application, there is provided the composition for resist underlayer film formation according to the first aspect, wherein the functional group represented by formula (3) is a group represented by formula (4) below.

[0027]

[0028] (in formula (4), * represents a binding end with an oxygen atom)

[0029] As the third aspect in the present application, there is provided the composition for resist underlayer film formation according to the first aspect or the second aspect, wherein, in the repeating structural unit represented by formula (2), X 1 represents a divalent hydrocarbon group having 2 to 20 carbon atoms in a linear, branched or cyclic form, or a divalent organic group having 2 to 20 carbon atoms in a linear, branched or cyclic form having at least one sulfur atom or oxygen atom, or a divalent organic group including at least one aromatic ring having 6 to 20 carbon atoms or a heterocyclic ring having 3 to 12 carbon atoms, the heterocyclic ring having at least one sulfur atom or oxygen atom.

[0030] As the fourth aspect in the present application, there is provided the composition for resist underlayer film formation according to any one of the first aspect to the third aspect, wherein the copolymer includes a repeating structural unit 25% or more formed of a monomer including R 1

[0031] As the fifth aspect in the present application, there is provided the composition for resist underlayer film formation according to any one of the first aspect to the fourth aspect, further including a photocrosslinking agent.

[0032] As the sixth aspect in the present application, there is provided the composition for resist underlayer film formation according to any one of the first aspect to the fifth aspect, further including a compound represented by formula (5) below and / or a compound represented by formula (6).

[0033]

[0034] (in the formula, X 2 represents a carbonyl group or a methylene group, l and m each independently represent an integer of 0 to 5, a relational expression 3 ≤ l + m ≤ 10 is satisfied, R 3 represents an alkylene group or an alkenylene group having 1 to 4 carbon atoms or a single bond, k represents 0 or 1, and n represents an integer of 2 to 4)​

[0035] As the seventh aspect of the present application, there is provided the composition for forming an underlayer film for a resist according to any one of the first to sixth aspects, which further contains a surfactant.

[0036] As the eighth aspect of the present application, there is provided a method for producing an underlayer film for a resist, which comprises a heating step of applying the composition for forming an underlayer film for a resist according to any one of the first to seventh aspects on a substrate having a step difference, and then thermally curing it.

[0037] As the ninth aspect of the present application, there is provided the method for producing an underlayer film for a resist according to the eighth aspect, wherein the heating temperature in the heating step is 200 to 300°C.

[0038] As the tenth aspect of the present application, there is provided the method for producing an underlayer film for a resist according to the ninth aspect, which further comprises an exposure step of performing exposure.

[0039] As the eleventh aspect of the present application, there is provided a method for producing an underlayer film for a resist without performing an exposure step, which comprises a heating step of applying the composition for forming an underlayer film for a resist according to any one of the first to seventh aspects on a substrate having a step difference, and then thermally curing it at 250°C or higher.

[0040] Effects of the Invention

[0041] The composition for forming an underlayer film for a resist according to the present application, which is applied to a substrate, and then exhibits high reflow property by a step of heating it, and a flat film can be formed even on a substrate having a step difference. Further, the cured film formed has an appropriate antireflection effect.

[0042] The composition for forming an underlayer film for a resist according to the present application, which contains a surfactant, thereby has an effect of improving the application property to a substrate.

[0043] The method for producing an underlayer film for a resist according to the present application, which is applied to a substrate, and then exhibits high reflow property by a step of heating it, and a flat film can be formed even on a substrate having a step difference. Further, the cured film formed has an appropriate antireflection effect.

[0044] Further, the method for producing an underlayer film for a resist according to the present application can cure the composition for forming an underlayer film for a resist according to the present application by combining a heating step and an exposure step, or on the other hand, can form a planarized film having planarity by curing the composition for forming an underlayer film for a resist according to the present application by heating it at a high temperature without performing an exposure step, and thus has an effect of simplifying the production process and improving work efficiency. DETAILED DESCRIPTION

[0045] <CO- POLYMER >

[0046] The copolymer as an essential component of the resist underlayer film-forming composition of the present application is preferably a copolymer having a repeating structural unit represented by the following formula (1) and / or a repeating structural unit represented by the following formula (2).

[0047]

[0048] (In formulae (1) and (2), R 1 represents a functional group represented by formula (3), in which formula (3), Q1and Q2each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and * represents a binding end to an oxygen atom, and in formula (2), X 1 represents an organic group having 1 to 50 carbon atoms, and i and j each independently represent 0 or 1.)

[0049] It is preferable that Q1and Q2of formula (3) each independently represent a hydrogen atom. That is, the functional group represented by formula (3) becomes a group represented by the following formula (4).

[0050]

[0051] (In formula (4), * represents a binding end to an oxygen atom.)

[0052] It is preferable that in the above copolymer, repeating structural units formed of a monomer containing R 1 be contained in 25% or more, and more preferably 50% or more.

[0053] It is preferable that the group X 1 in formula (2) represent a divalent hydrocarbon group having 2 to 20 carbon atoms in a linear, branched or cyclic form, or represent a divalent organic group having 2 to 20 carbon atoms in a linear, branched or cyclic form having at least one sulfur atom or oxygen atom, or represent a divalent organic group containing at least one aromatic ring having 6 to 20 carbon atoms or a heterocyclic ring having 3 to 12 carbon atoms, the heterocyclic ring having at least one sulfur atom or oxygen atom.

[0054] As the above aromatic ring, there can be mentioned, for example, a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a tetracene ring, a benzo[9,10]phenanthrene ring, a pyrene ring and a naphthalene ring.

[0055] As the above heterocyclic ring, there can be mentioned, for example, a triazine ring, a cyanuric acid ring, a pyrimidine ring, an imidazole ring, a carbazole ring.

[0056] Examples of a compound represented by the following formula as a monomer corresponding to the repeating unit represented by the above formula (1) in the above copolymer.

[0057]

[0058] Examples of the compound represented by the following formula as a monomer corresponding to the repeating unit represented by the above formula (2) in the above copolymer include the following compounds.

[0059]

[0060]

[0061] Examples of the copolymer having the repeating structural unit represented by the above formula (1) and the repeating structural unit represented by the above formula (2) include, for example, copolymers having the repeating structural unit represented by the following formulae (1a) to (1k).

[0062]

[0063]

[0064] The composition for forming a resist underlayer film of the present application can contain a compound represented by formula (5) and / or a compound represented by formula (6) as an arbitrary component.

[0065]

[0066] In the formula, X 2 represents a carbonyl group or a methylene group, each of l and m independently represents an integer of 0 to 5, and a relation of 3 ≤ l + m ≤ 10 is satisfied, R 3 represents an alkylene group or an alkenylene group having 1 to 4 carbon atoms or a single bond, k represents 0 or 1, and n represents an integer of 2 to 4.

[0067] Examples of the compound represented by the above formula (5) include, for example, the compounds represented by the following formulae (5-1) to (5-20).

[0068]

[0069] Examples of the compound represented by the above formula (6) include the compounds represented by the following formulae (6-1) to (6-31).

[0070]

[0071] The composition for forming a resist underlayer film of the present application can contain a compound represented by formula (5) and / or a compound represented by formula (6) as an arbitrary component.

[0072] <Photocrosslinking agent>

[0073] The resist underlayer film-forming composition of the present application does not require a thermal crosslinking agent. As to the photo crosslinking agent, it can be added as needed.

[0074] As the photo crosslinking agent, for example, a glycidyl ether compound, a glycidyl ester compound, an isocyanuric acid ester containing a glycidyl group, an epoxy cyclohexyl compound, an epoxy-substituted cyclohexyl compound, and resins thereof can be cited. The photo crosslinking agent used in the present application can be exemplified by, for example, the following.

[0075]

[0076] Formula (C-1) can be obtained as TEPIC-SS manufactured by Nissan Chemical Industries, Ltd.

[0077] Formula (C-2) can be obtained as MA-DGIC manufactured by Shikoku Chemicals Corporation.

[0078] Formula (C-3) can be obtained as EX-411 manufactured by Nagase Chemtex Corporation.

[0079] Formula (C-4) can be obtained as EX-521 manufactured by Nagase Chemtex Corporation.

[0080] Formula (C-7) can be obtained as RE810-NM manufactured by Japan Epoxy Resin Co., Ltd.

[0081] Formula (C-8) can be obtained as BATG manufactured by Showa Denko K.K.

[0082] Formula (C-9) can be obtained as EX-711 manufactured by Nagase Chemtex Corporation.

[0083] Formula (C-10) can be obtained as YD-4032D manufactured by DIC Corporation.

[0084] Formula (C-11) can be obtained as HP-4770 manufactured by DIC Corporation.

[0085] Formula (C-12) can be obtained as YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

[0086] Formula (C-13) can be obtained as EPICLON HP-4700 manufactured by DIC Corporation.

[0087] Formula (C-14) can be obtained as TEP-G manufactured by Asahi Organic Chemicals Industry Corporation.

[0088] Formula (C-15) is manufactured by Daiser Co., Ltd., with the product name Eco-D GT401. a, b, c, and d are 0 or 1 respectively, and a+b+c+d=1.

[0089] Formula (C-16) can be obtained as (Co., Ltd.) Daicel, under the product name EHPE-3150.

[0090] Formula (C-17) can be obtained as DIC Corporation under the trade name HP-7200L.

[0091] Formula (C-18) is available as Nippon Kayaku Co., Ltd. under the trade name EPPN-201.

[0092] Formula (C-19) can be obtained as manufactured by Asahi Kasei Epokishi Co., Ltd., under the trade name ECN-1229.

[0093] Formula (C-20) is available as manufactured by Nippon Kayaku Co., Ltd. under the trade name EPPN-501H.

[0094] Formula (C-21) can be obtained by Nippon Kayaku Co., Ltd. under the trade name NC-2000L.

[0095] Formula (C-22) can be obtained by Nippon Kayaku Co., Ltd. under the trade name NC-3000L.

[0096] Formula (C-23) can be obtained by Nippon Kayaku Co., Ltd. under the trade name NC-7000L.

[0097] Formula (C-24) is available as manufactured by Nippon Kayaku Co., Ltd. under the trade name NC-7300L.

[0098] Formula (C-25) is available as Nippon Kayaku Co., Ltd. under the trade name NC-3500.

[0099] Formula (C-26) can be obtained as DIC Co., Ltd., under the trade name EPICLON HP-5000.

[0100] Formula (C-27) is available as manufactured by Nippon Kayaku Co., Ltd. under the trade name FAE-2500.

[0101] Formula (C-28) is available as Nippon Kayaku Co., Ltd., under the trade name NC-6000.

[0102] <surfactants>

[0103] The composition for resist underlayer film formation of the present application can contain a surfactant as an arbitrary component in order to improve the coatability to a substrate. As the surfactant, for example, polyoxyethylene alkyl ether such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ether such as polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether, polyoxyethylene / polyoxypropylene block copolymer, sorbitan fatty acid ester such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, polyoxyethylene sorbitan fatty acid ester such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, nonionic surfactant such as Eftop EF301, Eftop EF303, Eftop EF352 (manufactured by Mitsubishi Material Electronic Chemical Co., Ltd.), Megafack F171, Megafack F173, Megafack R-30, Megafack R-30N, Megafack R-40-LM (manufactured by DIC Corp.), Florad FC430, Florad FC431 (manufactured by San-Ei Gen F.F.I., Inc.), Asahi Guard AG710, Surfon SC-382, Surfon SC-101, Surfon SC-102, Surfon SC-103, Surfon SC-104, Surfon SC-105, Surfon SC-106 (manufactured by AGC Corp.), fluorine-based surfactant, and silicone polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants can be added alone or in combination of two or more.

[0104] In the case where the above surfactant is used, the content of the surfactant is, for example, 0.01 to 5 parts by mass, and preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the content of the above copolymer.

[0105] <Organic solvent>

[0106] The resist underlayer film-forming composition of the present application can be prepared by dissolving each of the above components in a suitable organic solvent and used as a uniform solution. As such an organic solvent, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-hydroxypropionic acid ethyl ester, 2-hydroxy-2-methylpropionic acid ethyl ester, ethoxyacetic acid ethyl ester, glycolic acid ethyl ester, 2-hydroxy-3-methylbutyric acid methyl ester, 3-methoxypropionic acid methyl ester, 3-methoxypropionic acid ethyl ester, 3-ethoxypropionic acid ethyl ester, 3-ethoxypropionic acid methyl ester, pyruvic acid methyl ester, pyruvic acid ethyl ester, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone can be used. These organic solvents can be used alone or in combination of two or more. Further, a high-boiling organic solvent such as propylene glycol monobutyl ether, propylene glycol monobutyl ether acetate, or the like can also be used in combination with these organic solvents.

[0107] <Method for manufacturing resist underlayer film>

[0108] Next, if the method for manufacturing a resist underlayer film using the resist underlayer film-forming composition of the present application is described, the resist underlayer film-forming composition is applied on a substrate (for example, a silicon / silicon dioxide-coated, a glass substrate, an ITO substrate, or the like transparent substrate) used in the manufacture of a precision integrated circuit element by a suitable coating method such as a spin coater, a coater, or the like, and then baked (heated) on a hot plate to form a resist underlayer film. That is, it is a method for manufacturing a resist underlayer film including a heating step in which the resist underlayer film-forming composition is applied on a substrate and then heated at a high temperature.

[0109] The resist underlayer film-forming composition of the present application is not thermally cured even at a high temperature of up to 250°C, and is thermally cured by heating at a high temperature of 250°C or higher to form a flat resist underlayer film.

[0110] In the present application, the preferred heating temperature of the heating step is 200°C to 300°C.

[0111] In the case of heating at a high temperature of 250°C or higher, the resist underlayer film-forming composition is thermally cured, and a resist underlayer film can be formed without passing through an exposure step.

[0112] Further, in the present application, there is a method in which, after heating the composition for forming a lower resist film which has not been thermally cured in the heating step, a further exposure step of performing ultraviolet irradiation by an ultraviolet irradiation device is added to cause the resist lower film-forming composition to photocure.

[0113] The light for exposure is a chemical ray such as near ultraviolet, far ultraviolet, or ultraviolet (for example, EUV, wavelength 13.5 nm), and a light having a wavelength of, for example, 248 nm (KrF laser), 193 nm (ArF laser), 172 nm (xenon excimer), 157 nm (F2 laser) is used. Further, the exposure wavelength can use ultraviolet light of 150 nm to 248 nm, and further, a wavelength of 172 nm can be preferably used.

[0114] Crosslinking of the resist lower film is performed by this exposure. The exposure amount of the exposure step can be 10 mJ / cm 2 to 3000 mJ / cm 2 With the exposure amount in this range, a photo reaction occurs, crosslinking is formed, and solvent resistance is generated.

[0115] Examples

[0116] Hereinafter, specific examples of the resist lower film-forming composition of the present application will be described using the following examples, but the present application is not limited thereto.

[0117] The device and the like used for measurement of the weight average molecular weight of the reaction product obtained in the following synthesis example are shown.

[0118] Device: HLC-8320 GPC manufactured by Toyo Seiki Co., Ltd.

[0119] GPC column: TSKgel Super-Multipore HZ-N (2 pieces)

[0120] Column temperature: 40°C

[0121] Flow rate: 0.35 ml / minute

[0122] Eluent: THF

[0123] Standard sample: Polystyrene

[0124] The meanings of the abbreviations used in the following examples are as described below.

[0125] PGME: Propylene glycol monomethyl ether

[0126] RE810-NM: Diallyl bisphenol A type epoxy resin (the following formula (A))

[0127] BPA-CA: 2,2-bis(3-allyl-4-hydroxyphenyl)propane (Formula (B) below)

[0128] Ex-216L: Cyclohexanediethanol diglycidyl ether (Formula (C) below)

[0129] Ex-252: Hydrogenated bisphenol A diglycidyl ether (Formula (D) below)

[0130] Cis-1,2-Cyclohexanedicarboxylic Acid: Cis-1,2-cyclohexanedicarboxylic acid

[0131] PGMEA: Propylene glycol monomethyl ether acetate

[0132] EHPE-3150: 1,2-epoxy-4-(2-epoxyethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol

[0133]

[0134] <Synthesis example 1>

[0135] 26.00g of RE810-NM (manufactured by Nippon Kayaku Co., Ltd.), 20.81g of BPA-CA (manufactured by Konishi Chemical Co., Ltd.), and ethyltriphenyl bromide as a catalyst were added to 72.46g of PGME. 2.18 g of hydroquinone, used as a free radical scavenger, was added and reacted at 140 °C for 24 hours to obtain a solution containing the reaction products. After diluting to a 20 wt% solution using PGME, 147.90 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos (Co., Ltd.) and 147.90 g of cation exchange resin (product name: Amberlist [registered trademark] 15JWET, Organo (Co., Ltd.)) were added, and the mixture was stirred at 60 °C for 4 hours before filtration.

[0136] GPC analysis of the resulting reaction product was performed, and the weight-average molecular weight converted to standard polystyrene was 18,000. The resulting reaction product is presumed to be a copolymer having the structural units shown in the following formula (7).

[0137]

[0138] <Synthesis example 2>

[0139] The following were added to PGME48.10g: 9.00g of RE810-NM (manufactured by Nippon Kayaku Co., Ltd.), 14.98g of BPA-CA (manufactured by Konishi Chemical Co., Ltd.), and 6.28g of Ex-216L (manufactured by Nagasekemex Co., Ltd.). Ethyltriphenyl bromide was added as a catalyst. 1.57 g of hydroquinone, acting as a free radical scavenger, was added and reacted at 140 °C for 24 hours to obtain a solution containing the reaction products. The product was then redeprecipitated using methanol (320 g, manufactured by Kanto Chemical Co., Ltd.). The resulting precipitate was filtered and dried under reduced pressure at 60 °C for 24 hours to obtain the target polymer. After adjusting the solution to 20 wt% using PGME, 11.83 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos (Co., Ltd.) and 11.81 g of cation exchange resin (product name: Anbarrist [registered trademark] 15JWET, Organo (Co., Ltd.)) were added, and the mixture was stirred at 25 °C–30 °C for 4 hours before filtration.

[0140] GPC analysis of the reaction products was performed, and the weight-average molecular weight converted to standard polystyrene was 13,700. The resulting reaction products were presumed to be copolymers having the structural units shown in the following formula (8).

[0141]

[0142] <Synthesis Example 3>

[0143] The following were added to PGME48.10g: 9.00g of RE810-NM (manufactured by Nippon Kayaku Co., Ltd.), 14.98g of BPA-CA (manufactured by Konishi Chemical Co., Ltd.), 8.76g of Ex-252 (manufactured by Nagasekemex Co., Ltd.), and ethyltriphenyl bromide as a catalyst. 1.57 g of hydroquinone, acting as a free radical scavenger, was added and reacted at 140 °C for 24 hours to obtain a solution containing the reaction products. The product was redeprecipitated using methanol (320 g, manufactured by Kanto Chemical Co., Ltd.). The resulting precipitate was filtered and dried under reduced pressure at 60 °C for 24 hours to obtain the target polymer. After adjusting the solution to 20 wt% using PGME, 15.03 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos (Co., Ltd.) and 15.16 g of cation exchange resin (product name: Anbarrist [registered trademark] 15JWET, Organo (Co., Ltd.)) were added, and the mixture was stirred at 25 °C–30 °C for 4 hours before filtration.

[0144] The GPC analysis of the resultant reaction product was performed, and the result was a weight average molecular weight of 11,300 converted to a standard polystyrene. It was presumed that the resultant reaction product was a copolymer having a structural unit shown in the following formula (9).

[0145]

[0146] <Comparative Synthesis Example 1>

[0147] To PGME 148.30 g were added YX4000 (manufactured by Mitsubishi Chemical Corporation) 40.00 g, Cis-1,2-Cyclohexanedicarboxylic Acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 19.54 g, and ethyltriphenylphosphonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) as a catalyst 0.62 g, and heated to reflux under a nitrogen atmosphere for 13 hours. To the resultant solution were added cation exchange resin (product name: Amberlyst [Registered Trademark] 15 JWET, manufactured by Organo Corporation) 64.00 g and anion exchange resin (product name: Dowex [Registered Trademark] MONOSPHERE [Registered Trademark] 550A, manufactured by Muromachi Technos Co., Ltd.) 64.00 g, and stirred at 25°C to 30°C for 4 hours, followed by filtration. 4.01 g, and heated to reflux under a nitrogen atmosphere for 13 hours. To the resultant solution were added cation exchange resin (product name: Amberlyst [Registered Trademark] 15 JWET, manufactured by Organo Corporation) 64.00 g and anion exchange resin (product name: Dowex [Registered Trademark] MONOSPHERE [Registered Trademark] 550A, manufactured by Muromachi Technos Co., Ltd.) 64.00 g, and stirred at 25°C to 30°C for 4 hours, followed by filtration.

[0148] The GPC analysis of the resultant reaction product was performed, and the result was a weight average molecular weight of 11,300 converted to a standard polystyrene. It was presumed that the resultant reaction product was a copolymer having a structural unit shown in the following formula (9).

[0149]

[0150] <Comparative Synthesis Example 2>

[0151] To PGME 7.57 g were added PGMEA 17.67 g, EHPE-3150 (manufactured by Dicel Corporation) 5.00 g, 9-anthracene carboxylic acid 3.11 g, benzoic acid 2.09 g, and ethyltriphenylphosphonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) as a catalyst 0.62 g, and heated to reflux under a nitrogen atmosphere for 13 hours. To the resultant solution were added cation exchange resin (product name: Amberlyst [Registered Trademark] 15 JWET, manufactured by Organo Corporation) 16 g and anion exchange resin (product name: Dowex [Registered Trademark] MONOSPHERE [Registered Trademark] 550A, manufactured by Muromachi Technos Co., Ltd.) 16 g, and stirred at 25°C to 30°C for 4 hours, followed by filtration. 4.01 g, and heated to reflux under a nitrogen atmosphere for 13 hours. To the resultant solution were added cation exchange resin (product name: Amberlyst [Registered Trademark] 15 JWET, manufactured by Organo Corporation) 64.00 g and anion exchange resin (product name: Dowex [Registered Trademark] MONOSPHERE [Registered Trademark] 550A, manufactured by Muromachi Technos Co., Ltd.) 64.00 g, and stirred at 25°C to 30°C for 4 hours, followed by filtration.

[0152] The GPC analysis of the resultant reaction product was performed, and the result was a weight average molecular weight of 4,700 converted to a standard polystyrene. It was presumed that the resultant reaction product was a copolymer having a structural unit shown in the following formula (11).

[0153]

[0154] Preparation of the resist underlayer film-forming composition

[0155] Example 1

[0156] To 5.74 g of a solution (solvent: PGME used at the time of synthesis, solid content: 20.18 wt%) containing the copolymer 1.16 g obtained in the above Synthesis Example 1, PGME 8.49 g, PGMEA 5.65 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGME solution 0.12 g were mixed to prepare a 5.8 mass% solution. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm to prepare the resist underlayer film-forming composition.

[0157] Example 2

[0158] To 7.20 g of a solution (solvent: PGME used at the time of synthesis, solid content: 18.05 wt%) containing the copolymer 1.30 g obtained in the above Synthesis Example 2, PGME 7.06 g, PGMEA 5.61 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGME solution 0.13 g were mixed to prepare a 6.5 mass% solution. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm to prepare the resist underlayer film-forming composition.

[0159] Example 3

[0160] To 7.07 g of a solution (solvent: PGME used at the time of synthesis, solid content: 18.38 wt%) containing the copolymer 1.30 g obtained in the above Synthesis Example 3, PGME 7.19 g, PGMEA 5.61 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGME solution 0.13 g were mixed to prepare a 6.5 mass% solution. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm to prepare the resist underlayer film-forming composition.

[0161] Example 4

[0162] To 3.47 g of a solution (solvent: PGME used at the time of synthesis, solid content: 20.18 wt%) containing the copolymer 0.70 g obtained in the above Synthesis Example 1, PGME 3.74 g, PGMEA 2.72 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGMEA solution 0.07 g were added. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, and a composition for resist underlayer film formation was prepared.

[0163] Example 5

[0164] To 1.73 g of a solution (solvent: PGME used at the time of synthesis, solid content: 20.18 wt%) containing the copolymer 0.35 g obtained in the above Synthesis Example 1, GT-401 (DIC Corporation, trade name: Epikote GT401) 29.68 wt% PGMEA solution 1.18 g, PGME 5.13 g, PGMEA 1.69 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGMEA solution 0.28 g were added. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, and a composition for resist underlayer film formation was prepared.

[0165] Example 6

[0166] To 3.90 g of a solution (solvent: PGME used at the time of synthesis, solid content: 20.18 wt%) containing the copolymer 0.79 g obtained in the above Synthesis Example 1, GT-401 (DIC Corporation, trade name: Epikote GT401) 29.68 wt% PGMEA solution 0.88 g, PGME 6.65 g, PGMEA 3.36 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGMEA solution 0.21 g were added. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, and a composition for resist underlayer film formation was prepared.

[0167] Comparative Example 1

[0168] To 2.29 g of a solution (solvent: PGME used at the time of synthesis, solid content: 26.18 wt%) containing the copolymer 0.60 g obtained in the above Comparative Synthesis Example 1, PGME 4.89 g, PGMEA 2.76 g, and a surfactant (DIC Corporation, trade name: R-30N) 1 wt% PGME solution 0.060 g were added, and a 6.0 mass% solution was prepared. The solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, and a composition for resist underlayer film formation was prepared.

[0169] Comparative Example 2

[0170] To 19.52 g of a solution (solvent: PGME / PGMEA mixed solvent used at the time of synthesis, solid content: 23.26 wt%) containing the copolymer 4.51 g obtained in the above-mentioned Comparative Synthesis Example 2, was added 1.14 g of tetramethoxymethylglycoluril (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Shokubai Co., Ltd.), 3.41 g of a 1 wt% p-toluenesulfonic acid salt solution in PGME, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1 wt% surfactant (trade name: R-30, manufactured by DIC Corporation) solution in PGME, to prepare a 6.35 mass% solution. This solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, to prepare a resist underlayer film-forming composition. To 19.52 g of a solution (solvent: PGME / PGMEA mixed solvent used at the time of synthesis, solid content: 23.26 wt%) containing the copolymer 4.51 g obtained in the above-mentioned Comparative Synthesis Example 2, was added 1.14 g of tetramethoxymethylglycoluril (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Shokubai Co., Ltd.), 3.41 g of a 1 wt% p-toluenesulfonic acid salt solution in PGME, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1 wt% surfactant (trade name: R-30, manufactured by DIC Corporation) solution in PGME, to prepare a 6.35 mass% solution. This solution was filtered using a polytetrafluoroethylene-made microfilter having a pore size of 0.2 μm, to prepare a resist underlayer film-forming composition.

[0171] 〔Dissolution test in a photoresist solvent〕

[0172] The resist underlayer film-forming compositions prepared in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 were each applied to a silicon wafer by a spin coater. Then, a resist underlayer film (film thickness: 0.2 μm) was formed by baking on a hot plate at the temperature shown in Table 1 below for 1 minute. These resist underlayer films were immersed in PGME and PGMEA, which were used as the solvents for a photoresist solution, and it was confirmed that they were not dissolved in either of the solvents, the results of which are indicated by "O" in Table 1 below. In Comparative Example 1, since the resist underlayer film was dissolved in both of the solvents, more tests were not performed.

[0173] In addition, in Examples 4 to 6, in addition to the same tests as in Examples 1 to 3, after baking at the temperature shown in Table 1 below, ultraviolet irradiation was performed at 500 mJ / cm2using an ultraviolet irradiation device (wavelength: 172 nm) using a UV irradiation unit (wavelength: 172 nm) manufactured by Ushio Denki Co., Ltd., to form a resist underlayer film (film thickness: 0.2 μm). Then, the same tests as in Examples 1 to 3 were performed. Since the photocurable material was a material that is cured by light, not by heat at the temperature shown in Table 1, it was confirmed that the tendency was that the material was dissolved in a photoresist solution after baking, and was not dissolved after light irradiation.

[0174] 〔Test of optical parameters〕

[0175] The resist underlayer forming compositions prepared in Examples 1 to 6 and Comparative Example 2 were applied to a silicon wafer by a spin coater. Then, the resist underlayer films (film thickness 0.2 μm) were formed by baking on a hot plate at the temperatures shown in Table 1 below for 1 minute. Further, in Examples 4 to 6, after baking at the prescribed temperature, the ultraviolet rays were irradiated by using an ultraviolet irradiation device equipped with a UV irradiation unit (wavelength 172 nm) to cure the films by irradiation of 500 mJ / cm2of ultraviolet rays. 2 The refractive index (n value) and the extinction coefficient (k value) at a wavelength of 193 nm were measured using a spectroscopic ellipsometer (J. A. Woollam Co., VUV-VASE VU-302) for these resist underlayer films. The results are shown in Table 1 below. In order to impart sufficient antireflection properties to the resist underlayer film, it is desirable that the k value at a wavelength of 193 nm be 0.1 or more.

[0176] Table 1

[0177]

[0178] 〔Coverage test on a step substrate〕

[0179] As an evaluation of planarization, a comparison of the film thickness of the coated film was made between a trench pattern region (TRENCH) having a trench width of 50 nm and a pitch of 100 nm and an open region (OPEN) not having a pattern formed thereon using a SiO2substrate having a film thickness of 230 nm. After the resist underlayer forming compositions of Examples 1 to 6 and Comparative Example 2 were applied to the substrate at a film thickness of 200 nm, resist underlayer films (film thickness 0.2 μm) were formed by baking on a hot plate at the temperatures shown in Table 1 above for 1 minute. Further, in Examples 4 to 6, after baking at the prescribed temperature, the ultraviolet rays were irradiated by using an ultraviolet irradiation device equipped with a UV irradiation unit (wavelength 172 nm) to cure the films by irradiation of 500 mJ / cm2of ultraviolet rays. The step coverage of the substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation, and the film thickness difference between the trench region (patterned portion) and the open region (non-patterned portion) of the step substrate (the step coverage difference between the trench region and the open region, referred to as Bias) was measured to evaluate the planarization. The values of the film thickness and the step coverage difference in each region are shown in Table 2. The smaller the value of Bias (step coverage difference) in the evaluation of planarization, the higher the planarization.

[0180] Table 2

[0181]

[0182] If the planarization is compared, the results of Example 1 to Example 6 are less in the coating unevenness between the pattern region and the open region than the result of Comparative Example 2, and thus the resist underlayer film formed from the composition for forming a resist underlayer film of Example 1 to Example 6 can be said to have good planarization. Further, Example 1 and Example 4 are materials of the same composition, but the planarization of the same material can be improved by utilizing photocuring.

[0183] Industrial applicability

[0184] The composition for forming a resist underlayer film of the present application, after being coated on a substrate, exhibits high reflow properties by a heating process, and can be coated flat even on a substrate having unevenness, and a flat film can be formed. Furthermore, since it has an appropriate antireflection effect, it is useful as a composition for forming a resist underlayer film.

Claims

1. A composition for resist underlayer film formation, comprising a copolymer having a repeating structural unit represented by formula (1) and / or a repeating unit represented by formula (2), and an organic solvent, In formula (1) and formula (2), R 1 represents a functional group represented by formula (3), in formula (3), Q1and Q2each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, * represents a binding end with an oxygen atom, in formula (2), X 1 represents a linear, branched or cyclic divalent hydrocarbon group having 2 to 20 carbon atoms, or represents a linear, branched or cyclic divalent organic group having 2 to 20 carbon atoms and at least one sulfur atom or oxygen atom, i and j each independently represent 0 or 1.

2. The composition for resist underlayer film formation according to claim 1, wherein the functional group represented by formula (3) is a group represented by formula (4) below, In formula (4), * indicates a binding end to an oxygen atom.

3. The resist underlayer film-forming composition according to claim 1 or 2, comprising 25% or more of the repeating structural unit formed from the monomer comprising R ###0002### in the copolymer. 1 25% or more of the repeating structural unit formed from the monomer comprising R ###0002### in the copolymer.

4. The composition for resist underlayer film formation according to claim 1 or 2, further comprising a photo-crosslinking agent.

5. The composition for resist underlayer film formation according to claim 1 or 2, further comprising a compound represented by formula (5) below and / or a compound represented by formula (6), wherein X 2 represents a carbonyl group or a methylene group, each of l and m independently represents an integer of 0 to 5, a relational expression 3 < l + m < 10 is satisfied, R 3 represents an alkylene group or an alkenylene group having 1 to 4 carbon atoms or a single bond, k represents 0 or 1, and n represents an integer of 2 to 4.

6. The composition for resist underlayer film formation according to claim 1 or 2, further comprising a surfactant.

7. A method for manufacturing a resist underlayer film, comprising a heating process of coating the composition for resist underlayer film formation according to any one of claims 1 to 6 on a substrate having a step difference, and then heat-curing it.

8. The method for manufacturing a resist underlayer film according to claim 7, wherein the heating temperature of the heating process is 200°C to 300°C.

9. The method for manufacturing a resist underlayer film according to claim 8, further comprising an exposure process of performing exposure.

10. A method for manufacturing a resist underlayer film without an exposure process, comprising a heating process of coating the composition for resist underlayer film formation according to any one of claims 1 to 6 on a substrate having a step difference, and then heat-curing it at 250°C or higher.

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