9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, method for producing same, and composition for hard mask

Abstract

Provided is a novel 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, such as a novel 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate having high heat resistance. A 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate contains a monomer unit derived from a 9,9-bis(hydroxynaphthyl)-diarylfluorene.

Description

9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, its production method, and hard mask composition

[0001] The present invention relates to a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, a method for producing the same, and a composition for a hard mask.

[0002] For example, Patent Document 1 describes a method for forming a resist underlayer film for a multilayer resist film having at least three layers used in lithography, the method comprising the steps of: coating a substrate with a resist underlayer film material containing a resin obtained by novolakizing a compound having a bisnaphthol group; and curing the coated resist underlayer film material by heat treating it at a temperature exceeding 300° C. and not exceeding 600° C. for 10 to 600 seconds.

[0003] Furthermore, Patent Document 2 describes an underlayer film-forming material containing a novolac resin having a fluorene or tetrahydrospirobiindene structure. The underlayer film-forming material described in Patent Document 2 is a material for forming an underlayer film provided under a photoresist layer for processing a substrate to be processed, and involves irradiating a desired region of the photoresist layer with radiation and developing it with a developer to form a photoresist pattern, and then processing the underlayer film layer and the substrate to be processed using this photoresist pattern layer as a mask in a dry etching device.

[0004] Japanese Patent Publication No. 2010-122656 Japanese Patent Publication No. 2005-128509

[0005] The materials described in Patent Documents 1 and 2 are used as materials for forming hard masks in semiconductor microfabrication. For example, a spin-on-glass (SOG) film can be formed on a hard mask formed from these materials. The hard mask can be exposed to high temperatures when the spin-on-glass film is formed. For this reason, a material with higher heat resistance than the materials described in Patent Documents 1 and 2 is desired.

[0006] An object of one aspect of the present invention is to provide novel 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates, such as novel 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates, which have high heat resistance, and related techniques.

[0007] In order to solve the above problems, a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to one embodiment of the present invention contains a monomer unit derived from 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0008] A hard mask composition according to an embodiment of the present invention includes the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to an embodiment of the present invention.

[0009] Furthermore, a method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to one aspect of the present invention includes a step of producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate by reacting a monomer with an aldehyde in the presence of an acid catalyst or an alkali catalyst so that the molar ratio of aldehyde / monomer is within a range of 0.30 to 0.90, wherein the monomer is selected from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene and 9,9-bis(hydroxynaphthyl)-diphenylfluorene.

[0010] According to one aspect of the present invention, it is possible to provide novel 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates, such as novel 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates, which have high heat resistance, and related technologies.

[0011] <Terminology> As used herein, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0012] [1] 9,9-bis(hydroxynaphthyl)-diarylfluorene condensation product The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensation product contains a monomer unit derived from 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0013] The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate may be a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate containing a monomer unit derived from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene, a 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate containing a monomer unit derived from 9,9-bis(hydroxynaphthyl)-diphenylfluorene, or a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate containing both a monomer unit derived from 9,9-bis(hydroxynaphthyl)-diphenylfluorene. More specifically, the condensate is a resin in which at least one of two naphthol groups bonded to the 9-position of a fluorene group is independently condensed via a methylene group, and two aryl groups are bonded to a position other than the 9-position of the fluorene group. This improves the heat resistance of the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate.

[0014] The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate preferably has aryl groups at any two of the 1- to 8-positions other than the 9-position of the fluorene group of the condensate, and more preferably has aryl groups at the 2- and 7-positions.

[0015] The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate has a monomer unit having the structure shown in the following formula (I):

[0016]

[0017] In the formula (I), R １are each independently selected from alkyl groups having 1 to 4 carbon atoms; Ar are each independently selected from a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; n is each independently an integer of 1 or 2; m is each independently an integer of 0 or 1; * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

[0018] [1-1] 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate containing a monomer unit having the structure shown in formula (I) above is preferably a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate containing a monomer unit having the structure shown in formula (1) or formula (2) below.

[0019] The 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate is a condensate containing a monomer unit derived from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene. More specifically, the condensate is a resin in which at least one of two naphthol groups bonded to the 9-position of a fluorene group is independently condensed via a methylene group, and two naphthyl groups are bonded to positions other than the 9-position of the fluorene group.

[0020] The 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate has two naphthyl groups bonded to positions other than the 9-position of the fluorene group constituting the monomer unit, which improves heat resistance.

[0021] The 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate may be a 9,9-bis(hydroxynaphthyl)-di(2-naphthyl)fluorene condensate, and the monomer unit has a structure represented by the following formula (1):

[0022]

[0023] In the formula (1), R １are each independently selected from alkyl groups having 1 to 4 carbon atoms, where the alkyl group may be a linear or branched alkyl group; each n is preferably independently an integer of 1 or 2, and each m is preferably independently an integer of 0 or 1; * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

[0024] Furthermore, the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate containing a monomer unit having the structure shown in formula (I) above may be a 9,9-bis(hydroxynaphthyl)-di(1-naphthyl)fluorene condensate, in which the monomer unit has a structure shown in formula (2) below:

[0025]

[0026] It is preferable that the monomer unit has the following structure:

[0027] In the formula (2), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, where the alkyl group may be a linear or branched alkyl group; each n is preferably independently an integer of 1 or 2, and each m is preferably independently an integer of 0 or 1; * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

[0028] The 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate contains a monomer unit having the structure shown in the above formula (1), and the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate is preferably selected from a 9,9-bis(hydroxynaphthyl)-di(2-naphthyl)fluorene condensate and a 9,9-bis(hydroxynaphthyl)-di(1-naphthyl)fluorene condensate containing a monomer unit having the structure shown in the above formula (1).

[0029] [1-2] 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate containing a monomer unit having the structure shown in formula (I) above is preferably a 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate containing a monomer unit having the structure shown in formula (3) below.

[0030]

[0031] In the formula (3), each n is independently an integer of 1 or 2, each m is independently an integer of 0 or 1, * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bonds are bonded to hydrogen or a hydroxymethyl group, each n is independently an integer of 1 or 2, each m is independently an integer of 0 or 1, * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bonds are bonded to hydrogen or a hydroxymethyl group.

[0032] The 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate has two phenyl groups bonded to the 2- and 7-positions of the fluorene group constituting the monomer unit, which enhances heat resistance.

[0033] [1-3] Weight-average molecular weight, etc. The weight-average molecular weight (Mw) of a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, such as a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate and a 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate, is preferably 15,000 or less, more preferably 7,000 or less, and even more preferably 5,000 or less. The Mw of the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate is preferably 1,000 or more, more preferably 2,000 or more, thereby further improving the heat resistance of the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate and, for example, its durability against fluorine-based etchants. Furthermore, when the Mw of the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate is 15,000 or less, the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate can be more successfully embedded in the steps of a stepped substrate, for example.

[0034] Furthermore, the polydispersity (Mw / Mn) of 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates such as 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates and 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensates is preferably within the range of 1.0 to 3.5. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates can be determined by gel permeation chromatography (GPC) analysis using standard polystyrene, and Mw / Mn is calculated from the weight-average molecular weight (Mw) and number-average molecular weight (Mn) determined by GPC analysis.

[0035] Furthermore, 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates such as 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates preferably have an Onishi parameter calculated from the following formula of 2.0 or less, and more preferably 1.8 or less: Onishi parameter=N / (NC-NO) In the above formula, N represents the total number of atoms constituting the compound, NC represents the total number of carbon atoms constituting the compound, and NO represents the total number of oxygen atoms constituting the compound. Because the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates have an Onishi parameter of 2.0 or less, they have improved durability against etchants (etching agents) used in, for example, dry etching.

[0036] Furthermore, the ring parameter of a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, such as a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate, calculated from the following formula, is preferably 0.85 or more, more preferably 0.87 or more. Ring parameter=M ＣＹＣＬＯ / M In the above formula, M represents the molecular weight of the compound, and M ＣＹＣＬＯ represents the total atomic weight of carbon atoms in the cyclic structure of the compound. The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate has a ring parameter of 0.87 or more, which increases its durability against, for example, an etchant used in dry etching.

[0037] 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates, such as 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates and 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensates, are obtained by reacting a monomer with an aldehyde in the presence of an acid catalyst or an alkali catalyst, and are resins in which 9,9-bis(hydroxynaphthyl)-diarylfluorene is condensed via a methylene group derived from the aldehyde, and the monomer is at least one monomer selected from 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0038] Hereinafter, for convenience, unless otherwise specified, the naphthol resin is intended to be a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate exemplified by a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate and a 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensate, and here the naphthol resin is intended to be a naphthol novolac resin or a naphthol resole resin.

[0039] [2] Method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate A method for producing a naphthol resin, which is a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate, includes a step of producing the naphthol resin by reacting a monomer with an aldehyde in the presence of an acid catalyst or an alkali catalyst. Here, the monomer is preferably 9,9-bis(hydroxynaphthyl)-diarylfluorene, and is preferably selected from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene and 9,9-bis(hydroxynaphthyl)-diphenylfluorene.

[0040] [2-1] 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene, a monomer for obtaining naphthol resin, is a compound in which two naphthol (hydroxynaphthyl) groups are bonded to the 9-position of a fluorene group, and has naphthyl groups at any two of the 1- to 8-positions of the fluorene group.

[0041] More specifically, the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene preferably has a structure represented by the following formula (1a):

[0042]

[0043] In the formula (1a), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, n is each independently an integer of 1 or 2, and m is each independently an integer of 0 or 1. １ The alkyl group having 1 to 4 carbon atoms may be a straight-chain or branched alkyl group.

[0044] More specifically, the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene preferably has a structure represented by the following formula (2a):

[0045]

[0046] In the formula (2a), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, n is each independently an integer of 1 or 2, and m is each independently an integer of 0 or 1. １ The alkyl group having 1 to 4 carbon atoms may be a straight-chain or branched alkyl group.

[0047] More specifically, the monomer is preferably, for example, 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene, 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(1-naphthyl)fluorene, 9,9-bis(5-hydroxy-1-naphthyl)-2,7-di(2-naphthyl)fluorene, or 9,9-bis(5-hydroxy-1-naphthyl)-2,7-di(1-naphthyl)fluorene.

[0048] The two naphthol groups contained in the monomers represented by the formula (1a) and the formula (2a) each preferably independently have a hydroxyl group at the 6th to 8th positions, and more preferably have a hydroxyl group at the 6th position.

[0049] [2-2] 9,9-bis(hydroxynaphthyl)-diphenylfluorene 9,9-bis(hydroxynaphthyl)-diphenylfluorene, a monomer for obtaining naphthol resin, is a compound in which two naphthol (hydroxynaphthyl) groups are bonded to the 9-position of a fluorene group, and the fluorene group has phenyl groups at any two of the 1- to 8-positions.

[0050] More specifically, it is more preferable that the 9,9-bis(hydroxynaphthyl)-diphenylfluorene has a structure represented by the following formula (3a).

[0051] In the formula (3a), R１ are each independently selected from alkyl groups having 1 to 4 carbon atoms, n is each independently an integer of 1 or 2, and m is each independently an integer of 0 or 1. １ The alkyl group having 1 to 4 carbon atoms may be a straight-chain or branched alkyl group.

[0052] More specifically, the monomer is preferably, for example, 9,9-bis(6-hydroxy-2-naphthyl)-2,7-diphenylfluorene or 9,9-bis(5-hydroxy-1-naphthyl)-2,7-diphenylfluorene.

[0053] The two naphthol groups contained in the monomer represented by formula (3a) preferably each independently have a hydroxyl group at the 6th to 8th positions, and more preferably have a hydroxyl group at the 6th position.

[0054] [2-3] Aldehydes The aldehydes used in the reaction to obtain a naphthol resin are preferably at least one compound selected from the group consisting of compounds having a formyl group and polymers thereof, such as formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, salicylaldehyde, and glyoxal. One type of aldehyde may be used alone, or two or more types may be used in combination. Of these, the aldehyde is preferably selected from, for example, formaldehyde and paraformaldehyde.

[0055] The molar ratio of aldehydes / monomer to obtain a naphthol resin is preferably 0.30 or more, more preferably 0.40 or more, since the amount of aldehydes used can be reduced, and is preferably 0.90 or less, more preferably 0.80 or less, since gelation during the reaction can be suppressed.

[0056] [2-4] Reaction Solvent Examples of reaction solvents for obtaining naphthol resin include water; alcohols such as methanol, ethanol, propanol, and butanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; esters such as propylene glycol methyl ether acetate (PEGMEA) and γ-butyrolactone; and mixed solvents of these reaction solvents. It is preferable to use 100 to 500 parts by mass of the reaction solvent per 100 parts by mass of 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0057] Naphthol resins can be prepared by reacting 9,9-bis(hydroxynaphthyl)-diarylfluorene with aldehydes in the presence of an acid catalyst or an alkali catalyst. Examples of acid catalysts include inorganic acids, organic acids, and organic acid salts. Examples of inorganic acids include hydrochloric acid, sulfuric acid, and phosphoric acid. Examples of organic acids include oxalic acid, acetic acid, citric acid, tartaric acid, benzoic acid, and paratoluenesulfonic acid. Examples of organic acid salts include zinc acetate and zinc borate. These acid catalysts may be used alone or in combination.

[0058] The amount of the acid catalyst used in the reaction to obtain the naphthol resin is preferably 0.05 to 10.0 parts by mass, more preferably 0.5 to 5.0 parts by mass, per 100 parts by mass of 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0059] Various alkaline substances can be used as the alkaline catalyst for obtaining naphthol resin. Specific examples include inorganic alkaline substances and organic alkaline substances. Inorganic alkaline substances include, for example, alkali metal compounds, alkaline earth metal compounds, and ammonia. Alkali metal compounds include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal salts such as sodium carbonate. Alkaline earth metal compounds include, for example, hydroxides and oxides of calcium, magnesium, barium, and the like. Organic alkaline substances include, for example, tertiary amines such as triethylamine and trimethylamine, and cyclic amines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene). These alkaline catalysts may be used alone or in combination. By carrying out the reaction under an alkaline catalyst, it becomes easier to leave hydroxymethyl groups in the resulting naphthol resin after the reaction.

[0060] The amount of the alkali catalyst used in the reaction to obtain the naphthol resin is preferably 0.05 to 2.00 parts by mass, more preferably 0.10 to 1.00 parts by mass, per 100 parts by mass of 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0061] The reaction temperature for obtaining naphthol resin is preferably 80 to 110° C., more preferably 90 to 100° C. A reaction temperature of 80° C. or higher provides a sufficient reaction rate, while a reaction temperature of 110° C. or lower has the advantage of being easy to control. The reaction time may be, for example, 3 to 10 hours.

[0062] The naphthol resin obtained by the reaction may be washed with, for example, deionized water, pure water, etc. to remove the acid catalyst or alkali catalyst. Alternatively, the naphthol resin may be purified by, for example, reprecipitation using a hydrocarbon solvent such as hexane.

[0063] <Hard Mask Composition> 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates, such as 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates and 9,9-bis(hydroxynaphthyl)-diphenylfluorene condensates according to one embodiment of the present invention, are naphthol resins selected from naphthol novolac resins and naphthol resole resins, and have two naphthyl groups bonded to positions other than the 9-position of the fluorene group constituting the monomer unit, thereby enhancing heat resistance. Therefore, they can be used as resins contained in hard mask compositions.

[0064] The hard mask composition preferably contains the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to one embodiment of the present invention and an organic solvent. The hard mask composition may also contain a crosslinking agent, a crosslinking accelerator, and other additives, as long as the effects of the present invention are not impaired.

[0065] The crosslinking agent may be a polyhydric alcohol compound, and examples thereof include melamine compounds, guanamine compounds, glycoluril compounds, and urea compounds substituted with at least one group selected from a hydroxymethyl group, an alkoxymethyl group, and an acyloxymethyl group, as well as epoxy compounds, thioepoxy compounds, and isocyanate compounds, and compounds having an unsaturated double bond group such as an alkenyl ether group, and may also be a polyhydric alcohol compound.

[0066] The crosslinking accelerator may be, for example, an acid generator, and the acid generator may be any known acid generator, such as an onium salt acid generator, a diazomethane derivative, a nitrobenzyl sulfonate derivative, a disulfone acid generator, etc. The acid generator may be used alone, or two or more types of acid generators may be used in combination.

[0067] Examples of the onium salt acid generator include ammonium salts such as tetramethylammonium trifluoromethanesulfonate; iodonium salts such as diphenyliodonium trifluoromethanesulfonate and (p-tert-butoxyphenyl)phenyliodonium trifluoromethanesulfonate; and sulfonium salts such as triphenylsulfonium trifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate and bis(p-tert-butoxyphenyl)phenylsulfonium trifluoromethanesulfonate.

[0068] Examples of diazomethane derivatives include bisarylsulfonyldiazomethanes such as bis(benzenesulfonyl)diazomethane and bis(p-toluenesulfonyl)diazomethane; and bisalkylsulfonyldiazomethanes such as bis(cyclohexylsulfonyl)diazomethane.

[0069] Other examples of the acid generator include nitrobenzyl sulfonate derivatives such as 2,6-dinitrobenzyl p-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate; bissulfone derivatives such as bisnaphthylsulfonylmethane; and sulfonate derivatives of N-hydroxyimide compounds such as N-hydroxysuccinimide methanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide p-toluenesulfonate, and N-hydroxynaphthalimide methanesulfonate.

[0070] The hard mask composition may contain an organic solvent (dilution solvent) to improve coating workability. The same solvent as the reaction solvent used to obtain the naphthol resin can be used as the organic solvent, and therefore a description thereof will be omitted. The concentration of the naphthol resin contained in the hard mask composition is preferably within the range of 1 to 30% by mass, and more preferably within the range of 10 to 25% by mass. This allows the naphthol resin to more effectively fill in the steps of the substrate, thereby forming a hard mask.

[0071] The hard mask composition may also include other additives, such as, for example, surfactants, plasticizers, and the like.

[0072] The hard mask composition according to one embodiment of the present invention can be preferably used as a composition for forming a hard mask layer (hard mask) in a multilayer resist film to be subjected to lithography for performing fine processing on a substrate.

[0073] The multilayer resist film may be, for example, a three-layer resist film including a hard mask layer (lower layer film) formed on the surface to be processed of the substrate, an anti-reflection layer (middle layer film) formed on the hard mask layer, and a resist layer (upper layer film) formed on the anti-reflection layer.

[0074] The substrate to be processed may have steps of different heights formed along the thickness direction of the substrate, and for example, unevenness may be formed at different heights by gates, fins, etc. that constitute semiconductor elements. Such a substrate may be referred to as a stepped substrate. The substrate may be a silicon wafer substrate, but is not limited to this, and may also be a compound semiconductor such as SiC or SiN.

[0075] The hard mask layer formed from the hard mask composition covers the surface of the substrate to be processed while filling in any steps in the substrate, thereby forming a hard mask layer with a flat surface on the surface of the substrate to be processed.

[0076] The hard mask composition can be applied to the surface of a substrate to be processed by a known application method such as spin coating, and then dried under heat to remove the organic solvent. The heat drying is preferably performed under conditions of 90 to 130° C. in an inert gas atmosphere.

[0077] The thickness of the hard mask layer may be appropriately designed depending on the height of the steps formed on the substrate, and is not limited thereto, but may be 600 to 1400 nm, and preferably 800 to 1200 nm.

[0078] By covering the steps of the substrate with a hard mask layer having a flat surface, it is possible to prevent the thickness of the anti-reflective layer formed on the hard mask layer by CVD and ALD from varying in thickness in the thickness direction of the substrate. In other words, because an anti-reflective layer is formed with a uniform thickness, it is not suitable for filling the steps of the substrate without forming a hard mask layer. However, by filling the hard mask layer into the stepped substrate, it is possible to make the thickness of the anti-reflective layer uniform in the thickness direction of the stepped substrate. By forming a hard mask layer with a flat surface, it is possible to suppress the thickness variation of the anti-reflective layer and resist layer formed thereon, thereby increasing the depth of focus of lithography and increasing the process tolerance.

[0079] Examples of antireflective layers formed by CVD and ALD include silicon oxide (SiO) films, silicon nitride (SiN) films, and silicon oxynitride (SiON) films. The hard mask composition contains a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to one embodiment of the present invention, thereby improving heat resistance. That is, the hard mask composition has improved heat resistance to substrate temperatures of 300 to 500°C when forming an antireflective layer on a hard mask layer formed from the hard mask composition. However, the antireflective layer is not limited thereto, and may be an antireflective layer formed by spin-coating a composition containing polysilsesquioxane.

[0080] The resist layer formed on the antireflective layer may be either a positive resist or a negative resist, and a known photoresist composition may be used. The thickness of the resist layer may be set depending on the type of photoresist composition and is not limited, but may be 30 to 500 nm, preferably 50 to 400 nm. By forming the resist layer on the antireflective layer, the multilayer resist film enables high-resolution patterning even on a substrate with steps of different heights.

[0081] When patterning the resist layer, exposure is preferably carried out with high-energy rays having a wavelength of 300 nm or less, such as an excimer laser of 248 nm, 193 nm, or 157 nm, soft X-rays of 3 to 20 nm, an electron beam, X-rays, etc. After exposure, the resist layer is washed with a washing solution, whereby the desired pattern is developed.

[0082] The anti-reflection layer is preferably etched using the resist layer with the developed pattern as a mask. The anti-reflection layer may be etched by dry etching, for example, using CF4 as an etchant. ４ , CHF ３ , C ２ F ６ A fluorocarbon-based gas such as chlorofluorocarbon (CFC) gas can be used. The hard mask layer formed from the hard mask composition contains the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to one embodiment of the present invention, thereby improving the film remaining rate after dry etching. This prevents the hard mask layer from becoming distorted, which can occur when the hard mask layer is exposed to an etchant, and thus prevents deformation of the pattern formed on the antireflective layer.

[0083] After forming a desired pattern in the anti-reflection layer, a pattern may be formed in the hard mask layer by, for example, plasma etching using oxygen gas and hydrogen gas as etchants.

[0084] After forming the desired pattern in the hard mask layer, e.g., CF ４ , CHF ３ , C ２ F ６ A pattern is formed on a workpiece by plasma etching using a fluorocarbon-based gas such as chlorofluorocarbon (CFC) as an etchant.

[0085] Thereafter, the substrate can be immersed in a stripping solution to remove the multilayer resist film, and then cleaned by ashing with oxygen plasma, etc. This allows the residue of the multilayer resist film to be removed from the substrate on which wiring has been formed according to the pattern.

[0086] [Summary] The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to embodiment 1 of the present invention contains a monomer unit derived from 9,9-bis(hydroxynaphthyl)-diarylfluorene.

[0087] Furthermore, a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to Aspect 2 of the present invention is a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate in Aspect 1, which contains a monomer unit derived from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene.

[0088] Furthermore, the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to aspect 3 of the present invention is the same as that of aspect 1 or 2, wherein the monomer unit has a structure represented by the following formula (I): In the formula (I), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms; Ar are each independently selected from a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; n is each independently an integer of 1 or 2; m is each independently an integer of 0 or 1; * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

[0089] Furthermore, in accordance with a fourth aspect of the present invention, there is provided a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate in accordance with the third aspect, wherein the monomer unit has a structure represented by the following formula (1): In the formula (1), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, n is each independently an integer of 1 or 2, m is each independently an integer of 0 or 1, * represents a bond, at least one of which is bonded to another monomer unit via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

[0090] The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to Aspect 5 of the present invention is preferably the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to any one of Aspects 1 to 4, wherein the monomer unit is preferably a monomer unit derived from 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene.

[0091] Furthermore, the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to Aspect 6 of the present invention is preferably in any one of Aspects 1 to 5 above, and has a weight average molecular weight (Mw) in the range of 1,000 to 15,000.

[0092] Furthermore, the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to Aspect 7 of the present invention, in Aspects 2 or 4, preferably has a weight average molecular weight (Mw) in the range of 1,000 to 15,000.

[0093] A hard mask composition according to an eighth aspect of the present invention contains the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to any one of the first to seventh aspects.

[0094] A ninth aspect of the present invention provides a method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, comprising the step of producing a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate by reacting a monomer with an aldehyde in the presence of an acid catalyst or an alkali catalyst so that the molar ratio of aldehyde / monomer is within a range of 0.30 to 0.90, wherein the monomer is selected from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene and 9,9-bis(hydroxynaphthyl)-diphenylfluorene.

[0095] A tenth aspect of the present invention provides a method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate in the above-mentioned ninth aspect, wherein the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene has a structure represented by the following formula (1a): In the formula (1a), R １are each independently selected from alkyl groups having 1 to 4 carbon atoms; n is each independently an integer of 1 or 2; and m is each independently an integer of 0 or 1.

[0096] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0097] An embodiment of the present invention will now be described.

[0098] [1] Analysis Method [1-2] Gel Permeation Chromatography (GPC) Analysis Each of the reaction products of Examples 1 to 5 and Comparative Examples 1 and 2 was diluted with THF to a concentration of 0.1% to prepare a sample for GPC measurement.

[0099] The obtained GPC measurement sample was subjected to GPC measurement under the following measurement conditions, and from the results, the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were measured, and the dispersity (Mw / Mn) was evaluated. GPC measurement device: HCL-8120GPC (manufactured by Tosoh Corporation) Column: TSKgel G3000HXL 7.8 x 300 mm x 1 (manufactured by Tosoh Corporation) TSKgel G2000HXL 7.8 x 300 mm x 2 (manufactured by Tosoh Corporation) "TSKgel" is a registered trademark of the company Column temperature: 40°C Detector: RI (differential refractive index detector) Solvent: THF Flow rate: 0.800 mL / min Standard polystyrene: PStQuick E (manufactured by Tosoh Corporation) PStQuick F (manufactured by Tosoh Corporation)

[0100] [2] Synthesis of Novolac Resin of 9,9-bis(hydroxynaphthyl)-diarylfluorene [Example 1] 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene (8.0 g, manufactured by Osaka Gas Chemicals Co., Ltd.), 37% formalin (0.549 g), and oxalic acid (0.33 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the mixture was stirred at 100° C. for 6 hours. After the reaction, the mixture was dissolved in 20 g of methyl isobutyl ketone and thoroughly washed with water to remove the catalyst and metal impurities. The solvent was then removed under reduced pressure, followed by the addition of methoxypropyl acetate (PEGMEA) and concentration under reduced pressure to obtain a 20% by mass solution of 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene condensate. The weight average molecular weight by GPC analysis was Mw 2885, and Mw / Mn was 1.28.

[0101] Example 2: 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene (8.0 g), 37% formalin (0.415 g), and oxalic acid (0.125 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the mixture was stirred at 100°C for 6 hours. After the reaction, the acid contained in the reaction product was removed using the same procedure as in Example 1. Subsequently, methoxypropyl acetate (PEGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene condensate. The weight-average molecular weight (Mw) measured by GPC analysis was 2088, and the Mw / Mn ratio was 1.18.

[0102] Example 3: 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene (8.0 g), 37% formalin (0.646 g), and oxalic acid (0.125 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the reaction was carried out at 100°C for 6 hours. After the reaction, the acid contained in the reaction product was removed according to the same procedure as in Example 1. Subsequently, methoxypropyl acetate (PEGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene condensate. The weight-average molecular weight (Mw) by GPC analysis was 3912, and the Mw / Mn was 1.47.

[0103] Example 4: 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(1-naphthyl)fluorene (8.0 g, manufactured by Osaka Gas Chemicals Co., Ltd.), 37% formalin (0.549 g), and oxalic acid (0.44 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the mixture was stirred at 100°C for 6 hours. After the reaction, the mixture was dissolved in 20 g of methyl isobutyl ketone, thoroughly washed with water to remove the catalyst and metal impurities, and then the solvent was removed under reduced pressure. Subsequently, methoxypropyl acetate (PGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(1-naphthyl)fluorene condensate. The weight-average molecular weight (Mw) measured by GPC analysis was 2823, and the Mw / Mn ratio was 1.27.

[0104] Example 5: 9,9-bis(6-hydroxy-2-naphthyl)-2,7-diphenylfluorene (8.0 g, manufactured by Osaka Gas Chemicals Co., Ltd.), 37% formalin (0.700 g), and oxalic acid (0.66 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the mixture was stirred at 100°C for 6 hours. After the reaction, the mixture was dissolved in 20 g of methyl isobutyl ketone, thoroughly washed with water to remove the catalyst and metal impurities, and then the solvent was removed under reduced pressure. Subsequently, methoxypropyl acetate (PGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 9,9-bis(6-hydroxy-2-naphthyl)-2,7-diphenylfluorene condensate. The weight-average molecular weight (Mw) by GPC analysis was 2997, and the Mw / Mn was 1.32.

[0105] Comparative Example 1: 6,6'-(9H-fluorene-9,9-diyl)bis(naphthalen-2-ol) (8.0 g), 37% formalin (1.069 g), and oxalic acid (0.33 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the reaction was carried out at 100°C for 6 hours. After the reaction, the acid contained in the reaction product was removed according to the same procedure as in Example 1. Subsequently, methoxypropyl acetate (PEGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 6,6'-(9H-fluorene-9,9-diyl)bis(naphthalen-2-ol) condensate. The weight average molecular weight (Mw) by GPC analysis was 2500, and the Mw / Mn was 1.20.

[0106] Comparative Example 2: 9,9-bis(4-hydroxyphenyl)fluorene (8.0 g), 37% formalin (1.770 g), and oxalic acid (0.558 g) were charged into a 200 mL reaction vessel equipped with a thermometer, a condenser, and a magnetic stirrer, and the reaction was carried out at 100°C for 8 hours. After the reaction, the acid contained in the reaction product was removed according to the same procedure as in Example 1. Subsequently, methoxypropyl acetate (PEGMEA) was added, and the mixture was concentrated under reduced pressure to obtain a 20% by mass solution of 9,9-bis(4-hydroxyphenyl)fluorene condensate. The weight-average molecular weight (Mw) measured by GPC analysis was 12,600, and the Mw / Mn ratio was 4.15.

[0107] [3] Evaluation Methods [3-1] Onishi Parameter The Onishi parameter was calculated from the following formula: Onishi parameter = N / (NC-NO) In the above formula, N represents the total number of atoms constituting the compound, NC represents the total number of carbon atoms constituting the compound, and NO represents the total number of oxygen atoms constituting the compound. The N, NC, and NO of the compound used to calculate the Onishi parameter were determined based on the structure of the condensate.

[0108] [3-2] Ring parameter The ring parameter was calculated using the following formula: Ring parameter = M ＣＹＣＬＯ / M In the above formula, M represents the molecular weight of the compound, and M ＣＹＣＬＯ represents the total atomic weight of carbon atoms in the ring structure of the compound. M of the compound for calculating the ring parameter is determined based on the structure of the condensate, and M ＣＹＣＬＯ asked for.

[0109] [3-3] Evaluation of film remaining rate (etching resistance) The film remaining rate was evaluated for each of Examples 1 to 3 and Comparative Examples 1 and 2. The film remaining rate was evaluated as the rate of the organic film remaining on the silicon substrate after dry etching.

[0110] To prepare the sample, the compound was applied to a silicon substrate (diameter 10.16 cm) by spin coating, and then the coated silicon substrate was placed on a hot plate at 350°C and baked for 60 seconds. This resulted in the formation of an organic film with a thickness of 1000 nm on the silicon substrate. This organic film was used as a sample for measuring the residual film rate.

[0111] The dry etching conditions for evaluating the remaining film rate are as follows: Device: Compact Etcher FA-1-TK (manufactured by Samco Corporation) RF power: 200 W CF ４ Gas flow rate: 20 sccm (mL / min) Dry etching time: 120 seconds The film thickness after etching was measured using F20-UV (film thickness measurement system; manufactured by Filmetrics Inc.).

[0112] The remaining film ratio was measured as the ratio of the organic film remaining on the silicon substrate after dry etching.

[0113] Residual film ratio=b / a×100 The film thickness before etching is defined as a, and the film thickness after etching is defined as b.

[0114] [3-4] Evaluation of Thermal Decomposition Temperature The resin compounds obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were reprecipitated using hexane to prepare measurement samples, and the thermal decomposition temperatures were evaluated. Using a simultaneous differential thermal and thermogravimetric analyzer: STA200RV (manufactured by Hitachi High-Tech Science Corporation), the thermal weight loss was measured in an air atmosphere at a temperature increase rate of 10°C / min in the range of 50 to 700°C, and the thermal decomposition temperature of the resin was determined.

[0115] [4] Evaluation Results The evaluation results for the resin compounds of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0116]

[0117] As shown by the above evaluation results, the 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensates of Examples 1 to 5 had a high film residual ratio and a high thermal decomposition temperature of 500°C or higher in Examples 1 to 3 and 400°C or higher in Examples 4 and 5, and it was confirmed that they can be suitably used as hard masks in multilayer resist films.

[0118] The present invention can be used, for example, as a hard mask for a multilayer resist film used in the microfabrication of semiconductor elements.

Claims

1. 9,9-bis(hydroxynaphthyl)-diarylfluorene condensates containing monomer units derived from 9,9-bis(hydroxynaphthyl)-diarylfluorene.

2. The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to claim 1, which is a 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene condensate containing a monomer unit derived from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene.

3. The monomer unit has the structure shown in formula (I): In the formula (I), R １ are each independently selected from an alkyl group having 1 to 4 carbon atoms; each Ar is independently selected from a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; each n is independently an integer of 1 or 2; each m is independently an integer of 0 or 1; * represents a bond, at least one of which is bonded to another of the monomer units via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

4. The monomer unit has a structure represented by the following formula (1): In the formula (1), R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, each n is independently an integer of 1 or 2, each m is independently an integer of 0 or 1, and * represents a bond, at least one of which is bonded to another of the monomer units via a methylene group, and the remaining bond is bonded to a hydrogen atom or a hydroxymethyl group.

5. The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to any one of claims 1 to 4, wherein the monomer unit is a monomer unit derived from 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene.

6. The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to any one of claims 1 to 5, having a weight average molecular weight (Mw) in the range of 1,000 to 15,000.

7. The 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to claim 2 or 4, which has a weight average molecular weight (Mw) in the range of 1,000 to 15,000.

8. A composition for hard masks, comprising the 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to any one of claims 1 to 7.

9. A method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate, comprising the step of producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate by reacting a monomer with an aldehyde in the presence of an acid catalyst or an alkali catalyst so that the molar ratio of aldehyde / monomer is within the range of 0.30 to 0.90, wherein the monomer is selected from 9,9-bis(hydroxynaphthyl)-dinaphthylfluorene and 9,9-bis(hydroxynaphthyl)-diphenylfluorene.

10. The monomer has a structure represented by the following formula (1a): wherein R １ are each independently selected from alkyl groups having 1 to 4 carbon atoms, n is each independently an integer of 1 or 2, and m is each independently an integer of 0 or 1. The method for producing a 9,9-bis(hydroxynaphthyl)-diarylfluorene condensate according to claim 9.

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