JP2020056889A - Composition for forming resist lower layer film, resist lower layer film, and resist pattern formation method - Google Patents

Abstract

To provide a composition for forming a resist lower layer film which is excellent in a coating property, storage stability and a resist sensitivity change suppression property, a resist lower layer film, and a resist pattern formation method.SOLUTION: A composition for forming a resist lower layer film of the present invention contains a compound having an aromatic ring, an organic solvent and water, in which a percentage content of the water is 0.5 mass% or more and 15 mass% or less. The compound having the aromatic ring is preferably a polymer having a structural unit containing an aromatic ring. The polymer having the structural unit containing the aromatic ring is preferably a novolak resin, a resol resin, a styrene resin, an acenaphthylene resin, an indene resin, an arylene resin, a triazine resin, a calixarene resin or a combination thereof. The compound having the aromatic ring preferably has a hydroxyl group. A content of the water with respect to 100 pts.mass of the compound having the aromatic ring is preferably 5 pts.mass or more and 100 pts.mass or less.SELECTED DRAWING: None

Description

  The present invention relates to a composition for forming a resist underlayer film, a resist underlayer film, and a method for forming a resist pattern.

  In manufacturing a semiconductor device, a resist underlayer film is formed on one surface side of a substrate with a resist underlayer film forming composition, and a resist film forming composition is formed on a surface of the resist underlayer film opposite to the substrate. For example, a method of forming a resist pattern using the method described above is used. The resist underlayer film is etched using the resist pattern as a mask, and the substrate can be further etched using the obtained resist underlayer film pattern as a mask.

  Various studies have been made on materials used for such a composition for forming a resist underlayer film (see JP-A-2013-83833).

JP 2013-83833 A

  Recently, a composition for forming a resist underlayer film is required to have excellent coatability and storage stability, and to have excellent resist sensitivity change suppressing properties. However, the above conventional composition for forming a resist underlayer film cannot satisfy these requirements.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a resist underlayer film forming composition, a resist underlayer film, and a resist excellent in coating properties, storage stability, and resist sensitivity change suppressing properties. It is to provide a pattern forming method.

  The invention made to solve the above-mentioned problem includes a compound having an aromatic ring (hereinafter, also referred to as “[A] compound”), an organic solvent (hereinafter, also referred to as “[B] organic solvent”), and water ( Hereinafter, it is also referred to as “[C] water”), and the content of the [C] water is 0.5% by mass or more and 15% by mass or less.

  Another invention made to solve the above problem is a resist underlayer film formed from the composition for forming a resist underlayer film.

  Yet another invention made in order to solve the above-mentioned problem is a step of applying the composition for forming a resist underlayer film on one surface side of a substrate, and a step of applying the composition for forming a resist underlayer film. Heating the applied coating film, applying a resist film-forming composition on the side of the resist underlayer film formed by the heating step opposite to the substrate, and forming the resist film-forming composition A resist pattern forming method includes a step of exposing a resist film formed by a product coating step to radiation, and a step of developing the exposed resist film.

  The composition for forming a resist underlayer film of the present invention is excellent in coating properties, storage stability and resist sensitivity change suppressing properties. Since the resist underlayer film of the present invention is formed from the composition for forming a resist underlayer film, the resist underlayer film is excellent in resist sensitivity change suppression. According to the method of forming a resist pattern of the present invention, a resist underlayer film excellent in resist sensitivity change suppression properties can be formed, and a good resist pattern can be formed by using this resist underlayer film. Therefore, they can be suitably used for the manufacture of semiconductor devices, which are expected to be further miniaturized in the future.

<Composition for forming resist underlayer film>
The composition for forming a resist underlayer film contains a compound [A], an organic solvent [B], and water [C], and the content of the water [C] is 0.5% by mass or more and 15% by mass or more. It is as follows. The composition for forming a resist underlayer film may contain an acid generator (hereinafter, also referred to as “[D] acid generator”) and / or a cross-linking agent (hereinafter, also referred to as “[E] cross-linking agent”). Preferably, other optional components may be contained as long as the effects of the present invention are not impaired.

The composition for forming a resist underlayer film contains the components [A] to [C], and the content of the water [C] falls within the above-mentioned specific range, whereby the coating properties, storage stability, and resist sensitivity change suppression properties are improved. Excellent.
Hereinafter, each component will be described.

<[A] compound>
[A] The compound is a compound having an aromatic ring. The compound (A) can be used without any particular limitation as long as it has an aromatic ring. The compound [A] can be used alone or in combination of two or more.

  As the aromatic ring, for example, an aromatic carbon ring such as a benzene ring, a naphthalene ring, an anthracene ring, an indene ring, a pyrene ring, a fluorenylidene biphenyl ring, a fluorenylidene binaphthalene ring, a furan ring, a pyrrole ring, a thiophene ring, and phosphor And aromatic heterocycles such as rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, and triazine rings. Of these, aromatic carbocycles are preferred.

  [A] The upper limit of the mass content of silicon atoms in the compound is preferably 1% by mass, more preferably 0.1% by mass, and still more preferably 0.01% by mass. The mass content may be 0% by mass. When the mass content of silicon atoms in the compound (A) is within the above range, the etching resistance of the resist underlayer film can be further improved.

  Examples of the compound [A] include a polymer having a structural unit containing an aromatic ring (hereinafter, also referred to as “[A] polymer”), an aromatic ring-containing compound, and the like. “Polymer” refers to a compound having two or more structural units. “Aromatic ring-containing compound” refers to a compound containing an aromatic ring and having one structural unit. The molecular weight of the aromatic ring-containing compound is, for example, 300 or more and 3,000 or less. The use of the polymer [A] as the compound [A] of the composition for forming a resist underlayer film can further improve the coatability.

  [A] Examples of the polymer include a polymer having an aromatic ring in a main chain, and a polymer having no aromatic ring in a main chain and having an aromatic ring in a side chain. “Main chain” refers to the longest chain of atoms composed of atoms in a polymer. “Side chain” refers to a chain other than the longest chain among atoms formed by a polymer.

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

  [A] Examples of the polymer include a novolak resin, a resol resin, a styrene resin, an acenaphthylene resin, an indene resin, an arylene resin, a triazine resin, and a calixarene resin.

(Novolak resin)
The novolak resin is a resin obtained by reacting a phenolic compound with an aldehyde or a divinyl compound using an acidic catalyst. A plurality of phenolic compounds and aldehydes or divinyl compounds may be mixed and reacted.

  Examples of the phenolic compound include phenol, cresol, xylenol, resorcinol, bisphenol A, p-tert-butylphenol, p-octylphenol, 9,9-bis (4-hydroxyphenyl) fluorene, and 9,9-bis (3-hydroxy Phenols such as phenyl) fluorene and 4,4 ′-(α-methylbenzylidene) bisphenol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 9,9-bis ( Naphthols such as 6-hydroxynaphthyl) fluorene; anthrols such as 9-anthrol; pyrenols such as 1-hydroxypyrene and 2-hydroxypyrene;

  Examples of the aldehyde include aldehydes such as formaldehyde, benzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde and 1-formylpyrene, and aldehyde sources such as paraformaldehyde and trioxane.

  Examples of the divinyl compounds include divinylbenzene, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, 5-vinylnoborna-2-ene, divinylpyrene, limonene, and 5-vinylnorbornadiene.

  As the novolak resin, for example, a resin having a structural unit derived from phenol and formaldehyde, a resin having a structural unit derived from cresol and formaldehyde, a resin having a structural unit derived from dihydroxynaphthalene and formaldehyde, a resin derived from fluorenebisphenol and formaldehyde A resin having a structural unit derived from fluorene bisnaphthol and formaldehyde, a resin having a structural unit derived from hydroxypyrene and formaldehyde, a resin having a structural unit derived from hydroxypyrene and naphthaldehyde, 4,4 Resin having a structural unit derived from '-(α-methylbenzylidene) bisphenol and formaldehyde, a structure derived from a phenol compound and formylpyrene Resins having position, these combined resins, such as resins which some or all substituted with propargyl group of the hydrogen atoms of the phenolic hydroxyl groups of these resins.

(Resole resin)
The resole resin is a resin obtained by reacting a phenolic compound with an aldehyde using an alkaline catalyst.

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

  Examples of the styrene resin include polystyrene, polyvinyl naphthalene, polyhydroxystyrene, polyphenyl (meth) acrylate, and a resin obtained by combining these.

(Acenaphthylene resin)
Acenaphthylene resin is a resin having a structural unit derived from a compound having an acenaphthylene skeleton.

  Examples of the acenaphthylene resin include a copolymer of acenaphthylene and hydroxymethylacenaphthylene.

(Indene resin)
The indene resin is a resin having a structural unit derived from a compound having an indene skeleton.

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

  As the arylene resin, for example, polyarylene ether, polyarylene sulfide, polyarylene ether sulfone, polyarylene ether ketone, a resin having a structural unit containing a biphenylene skeleton, a structure derived from a compound containing a structural unit containing a biphenylene skeleton and an acenaphthylene skeleton And a resin having a unit.

  As the arylene resin, a resin having a biphenylene skeleton is preferable, and a resin having a structural unit having a biphenylene skeleton and a structural unit derived from a compound having an acenaphthylene skeleton is more preferable.

(Triazine resin)
A triazine resin is a resin having a structural unit derived from a compound having a triazine skeleton.

  Examples of the compound having a triazine skeleton include a melamine compound and a cyanuric acid compound.

  [A] When the polymer is a novolak resin, a resole resin, a styrene resin, an acenaphthylene resin, an indene resin, an arylene resin or a triazine resin, [A] the polymer has a weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC) ( The lower limit of Mw) is preferably 1,000, more preferably 2,000, still more preferably 3,000, and particularly preferably 4,000. Further, the upper limit of Mw is preferably 100,000, more preferably 70,000, further preferably 50,000, and particularly preferably 10,000. [A] By setting the Mw of the polymer in the above range, the coatability of the composition for forming a resist underlayer film can be further improved.

  [A] The lower limit of Mw / Mn (Mn is the number average molecular weight in terms of polystyrene by GPC) of the polymer is usually 1 and preferably 1.1. The upper limit of Mw / Mn is preferably 5, more preferably 3, and even more preferably 2.

  In the present specification, the Mw and Mn of the polymer were measured using a GPC column (TOSOH Corporation's "G2000HXL", two "G3000HXL", one "G4000HXL"), and the flow rate: 1.0 mL / min. , Elution solvent: tetrahydrofuran, column temperature: 40 ° C. The value is measured by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as a standard.

(Calix arene resin)
The calixarene resin is a cyclic oligomer in which a plurality of aromatic rings to which a hydroxy group is bonded via a hydrocarbon group or a part or all of the hydrogen atoms of the hydroxy group, the aromatic ring and the hydrocarbon group are substituted. It is a thing.

  Examples of the calixarene resin include cyclic 4- to 12-mers formed from phenol compounds such as phenol and naphthol and formaldehyde, and cyclic 4- to 12-mers formed from phenol compounds such as phenol and naphthol and benzaldehyde compounds. And a resin in which the hydrogen atom of the phenolic hydroxyl group of the cyclic body is replaced with a propargyl group or the like.

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

  [A] The compound preferably has a hydroxyl group. Examples of the hydroxyl group include a phenolic hydroxyl group and an alcoholic hydroxyl group. When the compound [A] has a hydroxyl group, the cross-linking reaction of the compound [A] can be promoted by the acid generator [D], the cross-linking agent [E] described below, and the like.

  The lower limit of the content of the compound (A) is preferably 50% by mass, more preferably 60% by mass, and still more preferably 65% by mass, based on the solid content of the composition for forming a resist underlayer film. The upper limit of the content is, for example, 100% by mass, preferably 99% by mass, more preferably 90% by mass, and still more preferably 80% by mass. The “solid content” of the composition for forming a resist underlayer film refers to all components other than [B] the organic solvent and [C] water.

[Method for synthesizing [A] compound]
The compound [A] may be synthesized according to a known method, or a commercially available product may be used.

<[B] Organic solvent>
[B] The organic solvent is not particularly limited as long as it can dissolve or disperse the compound [A], the water [C], and optional components contained as necessary.

  [B] Examples of the organic solvent include alcohol solvents, ketone solvents, ether solvents, ester solvents, nitrogen-containing solvents, and hydrocarbon solvents. [B] The organic solvent can be used alone or in combination of two or more.

  Examples of the alcohol solvent include a monoalcohol solvent such as methanol, ethanol and n-propanol, and a polyhydric alcohol solvent such as ethylene glycol and 1,2-propylene glycol.

  Examples of the ketone solvent include chain ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and cyclic ketone solvents such as cyclohexanone.

  Examples of ether solvents include chain ether solvents such as n-butyl ether, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran and 1,4-dioxane, and polyhydric alcohol partial ethers such as diethylene glycol monomethyl ether. System solvents and the like.

  Examples of the ester solvent include carbonate solvents such as diethyl carbonate, monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, diethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate. Examples include a hydric alcohol partial ether carboxylate-based solvent and a lactic acid ester-based solvent such as methyl lactate and ethyl lactate.

  Examples of the nitrogen-containing solvent include a chain nitrogen-containing solvent such as N, N-dimethylacetamide and a cyclic nitrogen-containing solvent such as N-methylpyrrolidone.

  Examples of the hydrocarbon-based solvent include an aliphatic hydrocarbon-based solvent such as decalin and an aromatic hydrocarbon-based solvent such as toluene.

  [B] The organic solvent is preferably an alcohol solvent, a ketone solvent, an ether solvent, an ester solvent and / or a nitrogen-containing solvent, more preferably a ketone solvent and / or an ester solvent, and a cyclic ketone solvent. And / or polyhydric alcohol partial ether carboxylate solvents are more preferred, and cyclohexanone and / or propylene glycol monomethyl acetate acetate are particularly preferred. By making the organic solvent [B] as described above, the content of water [C] in the composition for forming a resist underlayer film can be further increased, and as a result, storage stability and resist sensitivity change suppression properties can be improved. It can be further improved.

  [B] The content of the organic solvent is preferably 10 parts by mass, more preferably 100 parts by mass, further preferably 500 parts by mass, and particularly preferably 1,000 parts by mass with respect to 100 parts by mass of the compound [A]. . The upper limit of the content is preferably 10,000 parts by mass, more preferably 6,000 parts by mass, still more preferably 4,000 parts by mass, and particularly preferably 2,000 parts by mass.

<[C] water>
[C] As the water, for example, ultrapure water, ion exchange water, ultrafiltration water, reverse osmosis water, distilled water and the like can be used. Of these, ultrapure water is preferred. [C] water may be water contained in the above-mentioned [B] organic solvent.

  [C] The lower limit of the water content is 0.5% by mass, preferably 1% by mass, more preferably 2% by mass, and still more preferably 3% by mass, based on the composition for forming a resist underlayer film. Preferably, 4% by weight is particularly preferred. The upper limit of the content is 15% by mass, preferably 13% by mass, more preferably 11% by mass, still more preferably 10% by mass, and particularly preferably 9% by mass. The composition for forming a resist underlayer film can further improve the storage stability and the ability to suppress a change in the resist sensitivity by setting the content of the water [C] in the above range.

  [C] The lower limit of the water content is preferably 5 parts by mass, more preferably 10 parts by mass, still more preferably 30 parts by mass, and particularly preferably 50 parts by mass, based on 100 parts by mass of the compound [A]. The upper limit of the content is preferably 100 parts by mass, more preferably 90 parts by mass, further preferably 80 parts by mass, and particularly preferably 75 parts by mass.

  [C] The lower limit of the water content is preferably 0.5 parts by mass, more preferably 1 part by mass, still more preferably 2 parts by mass, and more preferably 3 parts by mass, based on 100 parts by mass of the organic solvent [B]. Particularly preferred. As a maximum of the above-mentioned content, 15 mass parts is preferred, 13 mass parts is more preferred, 11 mass parts is still more preferred, and 10 mass parts is especially preferred.

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

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

  Examples of the onium salt compound include sulfonium salts such as triphenylsulfonium trifluoromethanesulfonate and triphenylsulfonium nonafluoro-n-butanesulfonate, and 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate. , 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate and the like, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butane Iodonium salts such as Honeto, triethylammonium nonafluoro -n- butane sulfonate, and ammonium salts such as triethylammonium 1,1,3,3,3-pentafluoro-2- (pivaloyloxy) propanesulfonate and the like.

  Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide and N- (nonafluoro-n-butanesulfonyloxy) ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide and the like.

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

  When the composition for forming a resist underlayer film contains [D] an acid generator, the lower limit of the content of the [D] acid generator is 0.1 part by mass with respect to 100 parts by mass of the [A] compound. Is preferably 0.5 part by mass, more preferably 1 part by mass. As a maximum of the above-mentioned content, 20 mass parts is preferred, 10 mass parts is more preferred, and 5 mass parts is still more preferred. By setting the content of the acid generator [D] in the above range, the crosslinking reaction of the compound [A] can be more effectively promoted.

<[E] Crosslinking agent>
[E] The crosslinking agent is a component that forms a cross-linking between components such as the compound [A] by the action of heat or an acid. Even if the compound [A] has an intermolecular bond-forming group, the composition for forming a resist underlayer film further contains [E] a cross-linking agent to increase the hardness of the resist underlayer film. be able to. [E] The crosslinking agent may be used alone or in combination of two or more.

  [E] Examples of the crosslinking agent include polyfunctional (meth) acrylate compounds such as trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; epoxy compounds such as novolak type epoxy resin and bisphenol type epoxy resin; -Hydroxymethyl-4,6-dimethylphenol, 4,4 '-(1- (4- (1- (4-hydroxy-3,5-bis (methoxymethyl) phenyl) -1-methylethyl) phenyl) ethylidene ) Hydroxyphenol-substituted phenol compounds such as bis (2,6-bis (methoxymethyl) phenol), methoxymethyl-containing phenol compounds, alkoxyalkyl-containing phenol compounds such as ethoxymethyl-containing phenol compounds, and (poly) methylol Melamine, (poly) methylo And compounds having an alkoxy alkylated amino group, such as Le glycoluril.

  [E] As the crosslinking agent, compounds having an alkoxyalkylated amino group are preferred, and 1,3,4,6-tetra (methoxymethyl) glycoluril is more preferred.

  When the composition for forming a resist underlayer film contains [E] a crosslinking agent, the lower limit of the content of the [E] crosslinking agent is preferably 0.1 part by mass with respect to 100 parts by mass of the [A] compound. 1 part by mass is more preferable, 10 parts by mass is more preferable, and 30 parts by mass is particularly preferable. The upper limit of the content is preferably 100 parts by mass, more preferably 80 parts by mass, further preferably 60 parts by mass, and particularly preferably 50 parts by mass. When the content of the crosslinking agent [E] is in the above range, the crosslinking reaction of the compound [A] can be more effectively caused to occur.

<Other optional ingredients>
Other optional components include, for example, surfactants and adhesion aids.

<Method of preparing composition for forming resist underlayer film>
The composition for forming a resist underlayer film comprises [A] compound, [B] organic solvent and [C] water, and if necessary, [D] acid generator, [E] crosslinking agent, and other optional components. It can be prepared by mixing at a predetermined ratio and preferably filtering the obtained mixture through a filter having a size of 0.2 μm or less. The lower limit of the solid concentration of the composition for forming a resist underlayer film is preferably 0.1% by mass, more preferably 1% by mass, still more preferably 4% by mass, and particularly preferably 7% by mass. The upper limit of the solid content concentration is preferably 50% by mass, more preferably 30% by mass, still more preferably 20% by mass, and particularly preferably 15% by mass.

<Resist underlayer film>
The resist underlayer film of the present invention is formed from the composition for forming a resist underlayer film. Since the resist underlayer film is formed from the above-described composition for forming a resist underlayer film, the resist underlayer film is excellent in resist sensitivity change suppression.

<Method of forming resist underlayer film>
The method for forming the resist underlayer film includes a step of applying the composition for forming a resist underlayer film on one surface side of a substrate (hereinafter, also referred to as a “step of applying a composition for forming a resist underlayer film”) and the above-described method. The method includes a step of heating the coating film formed in the step of applying the composition for forming a resist underlayer film (hereinafter, also referred to as a “heating step”). According to the method for forming a resist underlayer film, since the above-described composition for forming a resist underlayer film is used, it is possible to form a resist underlayer film having excellent resist sensitivity change suppressing properties.

[Coating process of composition for forming resist underlayer film]
In this step, the composition for forming a resist underlayer film is applied to one surface of the substrate.

  Examples of the substrate include a silicon wafer and a wafer coated with aluminum. The method of applying the composition for forming a resist underlayer film is not particularly limited, and can be performed by an appropriate method such as spin coating, cast coating, or roll coating. Can be formed.

[Heating process]
In this step, the coating film formed in the above-described resist underlayer film forming composition coating step is heated. Thereby, a resist underlayer film is formed.

  The heating of the coating film is usually performed in the air, but may be performed in a nitrogen atmosphere. The heating may be performed in one stage or in multiple stages.

  As a lower limit of the above-mentioned heating temperature, 60 ° C is preferred, 80 ° C is more preferred, 150 ° C is still more preferred, and 200 ° C is especially preferred. The upper limit of the temperature is preferably 400 ° C, more preferably 350 ° C, still more preferably 300 ° C, and particularly preferably 270 ° C. The lower limit of the heating time is preferably 10 seconds, more preferably 30 seconds, and even more preferably 50 seconds. As an upper limit of the above-mentioned time, 300 seconds are preferred, 180 seconds are more preferred, and 120 seconds are still more preferred.

  In the method of forming a resist underlayer film, the coating film is heated to form a resist underlayer film, and the composition for forming a resist underlayer film contains an acid generator [D] and an acid generator [D]. When the agent is a radiation-sensitive acid generator, the film can be cured by a combination of exposure and heating to form a resist underlayer film. The radiation used for this exposure includes [D] electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and γ-rays; and electron beams, molecular beams, and ion beams. It is appropriately selected.

  The lower limit of the average thickness of the formed resist underlayer film is preferably 10 nm, more preferably 30 nm, and even more preferably 50 nm. The upper limit of the average thickness is preferably 3,000 nm, more preferably 1,000 nm, and still more preferably 300 nm.

<Method of forming resist pattern>
The method for forming a resist pattern includes a step of applying the composition for forming a resist underlayer film on one surface side of a substrate (a step of applying a composition for forming a resist underlayer film), and a step of coating the composition for forming a resist underlayer film. Heating the coating film formed by the heating step (heating step), and coating the resist underlayer film formed by the heating step on the side opposite to the substrate with the resist film forming composition (Hereinafter also referred to as “resist film forming composition coating step”) and a step of exposing the resist film formed by the resist film forming composition coating step to radiation (hereinafter also referred to as “exposure step”). ) And a step of developing the exposed resist film (hereinafter, also referred to as a “development step”).

  According to the method for forming a resist pattern, a resist underlayer film having excellent resist sensitivity change suppressing properties can be formed, and a good resist pattern can be formed by using the resist underlayer film.

The method for forming a resist pattern includes, after the heating step and before the step of applying the composition for forming a resist film, an intermediate layer (intermediate film) formed on the side of the resist underlayer film formed by the heating step opposite to the substrate. ) (Hereinafter, also referred to as “intermediate layer forming step”).
Hereinafter, each step will be described.

[Coating process of composition for forming resist underlayer film]
In this step, the composition for forming a resist underlayer film is applied to one surface side of the substrate. Thereby, a coating film is formed. This step is the same as the resist underlayer film forming composition coating step in the above-described resist underlayer film forming method.

[Heating process]
In this step, the coating film formed in the above-described resist underlayer film forming composition coating step is heated. Thereby, a resist underlayer film is formed. This step is the same as the heating step in the above-described method for forming a resist underlayer film.

[Intermediate layer forming step]
In this step, an intermediate layer is formed on the side of the resist underlayer film formed in the heating step opposite to the substrate. This intermediate layer is a layer provided with the above functions in order to further supplement the functions of the resist underlayer film and / or the resist film in the formation of the resist pattern, or to provide functions which these do not have. . For example, when the antireflection film is formed as an intermediate layer, the antireflection function of the resist underlayer film can be further supplemented.

  This intermediate layer can be formed of an organic compound or an inorganic oxide. Examples of the organic compound include commercially available products such as “DUV-42”, “DUV-44”, “ARC-28”, and “ARC-29” (above, Brewer Science); “AR-3”, “AR -19 "(above, Rohm and Haas Company) and the like. As the inorganic oxide, commercially available products include, for example, “NFC SOG01”, “NFC SOG04”, “NFC SOG080” (above, JSR Corporation) and the like. Further, as the inorganic oxide, polysiloxane, titanium oxide, alumina oxide, tungsten oxide, or the like formed by a CVD method can be used.

  The method for forming the intermediate layer is not particularly limited, and for example, a coating method, a CVD method, or the like can be used. Among these, the coating method is preferred. When the coating method is used, the intermediate layer can be continuously formed after the formation of the resist underlayer film. Further, the average thickness of the intermediate layer is appropriately selected according to the function required of the intermediate layer, but the lower limit of the average thickness of the intermediate layer is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 3,000 nm, more preferably 300 nm.

[Resist film forming composition coating process]
In this step, a composition for forming a resist film is applied to the surface of the resist underlayer film formed in the heating step opposite to the surface of the substrate. When the above-mentioned intermediate layer forming step is performed, a composition for forming a resist film is applied to the surface of the intermediate layer opposite to the substrate.

  In this step, specifically, after the resist film forming composition is applied so that the obtained resist film has a predetermined thickness, the solvent in the coating film is volatilized by heating (pre-baking). Then, a resist film is formed.

  As the composition for forming a resist film, for example, a positive or negative chemically amplified resist composition containing a radiation-sensitive acid generator, a positive resist composition containing an alkali-soluble resin and a quinonediazide-based photosensitizer, A negative resist composition containing an alkali-soluble resin and a cross-linking agent, tin or a metal or metalloid-containing resist composition containing a compound containing at least one atom selected from metal atoms or metalloid atoms such as zirconium, etc. No. When the resist composition containing a metal or metalloid is used as the composition for forming a resist film, the composition for forming a resist underlayer film can more effectively suppress the change in resist sensitivity. Further, as a composition for forming a resist film, a positive-type or negative-type chemically amplified resist composition, a positive-type resist composition containing an alkali-soluble resin and a quinonediazide-based photosensitizer, containing an alkali-soluble resin and a crosslinking agent When using a negative resist composition, or a metal or metalloid containing resist composition containing a compound containing at least one atom selected from metal atoms or metalloid atoms, the resist film forming method according to the resist pattern forming method The sensitivity of the resist film formed from the forming composition is further improved.

  As a minimum of solid concentration of a constituent for resist film formation, 0.3 mass% is preferred and 1 mass% is more preferred. The upper limit of the solid content concentration is preferably 50% by mass, and more preferably 30% by mass. In addition, the composition for forming a resist film is generally subjected to filtration with a filter having a pore size of 0.2 μm or less, for example, to be used for forming a resist film. In this step, a commercially available resist composition can be used as it is.

  The method for applying the composition for forming a resist film is not particularly limited, and examples thereof include a spin coating method. The heating temperature is appropriately adjusted according to the type of the composition for forming a resist film to be used, and the lower limit of the temperature is preferably 30 ° C, more preferably 50 ° C. The upper limit of the temperature is preferably 200 ° C, more preferably 150 ° C. The lower limit of the heating time is preferably 10 seconds, and more preferably 30 seconds. As an upper limit of the above-mentioned time, 600 seconds are preferred and 300 seconds are more preferred.

[Exposure process]
In this step, the resist film formed in the resist film forming composition coating step is exposed to radiation.

As the radiation used for the exposure, depending on the type of the radiation-sensitive acid generator used in the composition for forming a resist film, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-ray, and γ-ray; It is appropriately selected from particle beams such as a molecular beam and an ion beam. Among these, far ultraviolet rays or electron beams are preferable, and KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), F ₂ excimer laser light (wavelength 157 nm), Kr ₂ excimer laser light (wavelength 147 nm), ArKr Excimer laser light (wavelength 134 nm), extreme ultraviolet light (wavelength 13.5 nm, EUV) or an electron beam is more preferable, and KrF excimer laser light, ArF excimer laser light, EUV or an electron beam is further preferable.

  After the above-mentioned exposure, post-exposure baking (post-bake) can be performed to improve the resolution, pattern profile, developability and the like. The post-exposure baking temperature is appropriately adjusted depending on the type of the resist film forming composition to be used, etc., but the lower limit of the above temperature is preferably 50 ° C, more preferably 70 ° C. The upper limit of the temperature is preferably 200 ° C, more preferably 150 ° C. The lower limit of the heating time after exposure is preferably 10 seconds, more preferably 30 seconds. As an upper limit of the above-mentioned time, 600 seconds are preferred and 300 seconds are more preferred.

[Development step]
In this step, the exposed resist film is developed.

  This development may be an alkali development or an organic solvent development. As the developer, in the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl Diethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [ 4.3.0] -5-nonene and the like. An appropriate amount of a water-soluble organic solvent such as alcohols such as methanol and ethanol, a surfactant, and the like can be added to these alkaline aqueous solutions. In the case of organic solvent development, examples of the developer include various organic solvents exemplified as the organic solvent [B] of the composition for forming a resist underlayer film described above.

  After development with the above-mentioned developer, washing and drying are performed to form a predetermined resist pattern.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. Each physical property in the examples was measured by the following methods.

[Weight average molecular weight (Mw)]
The Mw of the polymer was measured using a GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL from Tosoh Corp.), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column The measurement was performed by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as a standard under the analysis condition of temperature: 40 ° C.

[Average film thickness]
The average thickness of the film was measured using a spectroscopic ellipsometer (“M2000D” manufactured by JA WOLLAM).

<Synthesis of [A] compound>
As the compound [A], polymers represented by the following formulas (A-1) to (A-8) (hereinafter, also referred to as “polymers (A-1) to (A-8)”) are shown below. Synthesized according to the procedure.

In the above formulas (A-6) and (A-7), * ^R indicates a site bonded to an oxygen atom.
In the above formulas (A-1), (A-4) and (A-8), the numbers given to the respective structural units indicate the content ratio (mol%) of the structural units.

[Synthesis Example 1-1] (Synthesis of Polymer (A-1))
Under a nitrogen atmosphere, 70 g of m-cresol, 57.27 g of p-cresol, 95.52 g of a 37% by mass aqueous formaldehyde solution and 381.82 g of methyl isobutyl ketone were added to and dissolved in a reaction vessel. After heating the obtained solution to 40 degreeC, 2.03 g of p-toluenesulfonic acid was added and it was made to react at 85 degreeC for 4 hours. The reaction solution was cooled to 30 ° C. or lower, and the reaction solution was poured into a mixed solution of methanol / water (50/50 (mass ratio)) to precipitate again. The precipitate was collected with a filter paper and dried to obtain a polymer (A-1). Mw of the polymer (A-1) was 50,000.

[Synthesis Example 1-2] (Synthesis of Polymer (A-2))
Under a nitrogen atmosphere, 150 g of 2,7-dihydroxynaphthalene, 76.01 g of a 37% by mass aqueous solution of formaldehyde and 450 g of methyl isobutyl ketone were added and dissolved in a reaction vessel. After the obtained solution was heated to 40 ° C, 1.61 g of p-toluenesulfonic acid was added and reacted at 80 ° C for 7 hours. The reaction solution was cooled to 30 ° C. or lower, and the reaction solution was poured into a mixed solution of methanol / water (50/50 (mass ratio)) to precipitate again. The precipitate was collected with a filter paper and dried to obtain a polymer (A-2). Mw of the polymer (A-2) was 3,000.

[Synthesis Example 1-3] (Synthesis of Polymer (A-3))
Under a nitrogen atmosphere, 20 g of 1-hydroxypyrene, 7.16 g of 2-naphthaldehyde and 82 g of propylene glycol monomethyl ether were charged into a reaction vessel and dissolved at room temperature. To the obtained solution, 8.81 g of methanesulfonic acid was added, and the mixture was stirred at 120 ° C. for 12 hours to perform polymerization. After completion of the polymerization, the polymerization reaction solution was poured into a large amount of a mixed solution of methanol / water (80/20 (vol%)), and the precipitate was filtered to obtain a polymer (A-3). Mw of the polymer (A-3) was 1,100.

[Synthesis Example 1-4] (Synthesis of Polymer (A-4))
A reaction vessel was charged with 34.5 g of 4,4 ′-(α-methylbenzylidene) bisphenol, 2.80 g of phenol, and 3.49 g of paraformaldehyde under a nitrogen atmosphere. Next, after adding and dissolving 60 g of propylene glycol monomethyl ether acetate, 0.220 g of p-toluenesulfonic acid monohydrate was added, followed by stirring at 95 ° C. for 6 hours to carry out polymerization. After completion of the polymerization, the polymerization reaction solution was put into a large amount of a mixed solution of methanol / water (70/30 (mass ratio)), and the precipitate was filtered to obtain a polymer (A-4). Mw of the polymer (A-4) was 4,200.

[Synthesis Example 1-5] (Synthesis of polymer (A-5))
Synthesis was performed except that 3,4.5 g of 4,4 ′-(α-methylbenzylidene) bisphenol, 2.80 g of phenol, and 3.49 g of paraformaldehyde in Synthesis Example 1-4 were changed to 37.9 g of bisphenolfluorene and 2.86 g of paraformaldehyde. The same operation as in Example 1-4 was performed to obtain a polymer (A-5). Mw of the polymer (A-5) was 4,500.

[Synthesis Example 1-6] (Synthesis of polymer (A-6))
In a reaction vessel, under a nitrogen atmosphere, 20 g of the polymer (A-2) synthesized in Synthesis Example 1-2, 80 g of N, N-dimethylacetamide, and 22 g of potassium carbonate were charged. Next, the mixture was heated to 80 ° C., and after adding 19 g of propargyl bromide, the mixture was stirred and reacted for 6 hours. Thereafter, 40 g of methyl isobutyl ketone and 80 g of water were added to the reaction solution to carry out a liquid separation operation. The obtained organic phase was poured into a large amount of methanol, and the precipitate was filtered to obtain a polymer (A-A). 6) was obtained. Mw of the polymer (A-6) was 3,200.

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

[Synthesis Example 1-8] (Synthesis of polymer (A-8))
After 35 g of 2-vinylnaphthalene and 2.9 g of 2-hydroxyethyl acrylate were dissolved in 112 g of cyclohexanone in the reaction vessel, the inside of the reaction vessel was replaced with nitrogen, and the temperature was raised to 60 ° C. 1.9 g of azobisisobutyronitrile dissolved in 47 g of cyclohexanone was added and reacted at 60 ° C. for 24 hours. After cooling, the reaction solution was poured into methanol for reprecipitation, and the obtained precipitate was dried to obtain a polymer (A-8). Mw of the polymer (A-8) was 11,000.

<Preparation of composition for forming resist underlayer film>
The [B] solvent, [D] acid generator, and [E] cross-linking agent used in the preparation of the composition for forming a resist underlayer film are shown below.

[[B] Organic solvent]
B-1: cyclohexanone B-2: propylene glycol monomethyl ether acetate

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

[[E] Crosslinking agent]
E-1: 1,3,4,6-tetrakis (methoxymethyl) glycoluril (compound represented by the following formula (E-1))

[Example 1-1]
[A] 7 parts by mass of (A-1) as a compound, [B] 60 parts by mass of (B-1) and 25 parts by mass of (B-2) as an organic solvent, and [C] 5 parts by mass of water. , [E] 3 parts by mass of (E-1) as a cross-linking agent, and the resulting mixture was filtered through a filter having a pore size of 0.2 μm to obtain a composition (J-1) for forming a resist underlayer film. Prepared.

[Examples 1-2 to 1-15 and Comparative Examples 1-1 to 1-8]
Except that the components and contents shown in Table 1 below were used, the operations were performed in the same manner as in Example 1-1, and the resist underlayer film forming compositions (J-2) to (J-15) and ( CJ-1) to (CJ-8) were prepared.

<Evaluation>
The coating composition and storage stability of the composition for forming a resist underlayer film prepared above were evaluated according to the following methods. The evaluation results are shown in Table 2 below.

[Coating property]
The composition for forming a resist underlayer film prepared above was coated on a silicon wafer (substrate) by a spin coating method using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited). Next, after heating at 90 ° C. for 60 seconds in the air atmosphere, cooling was performed at 23 ° C. for 60 seconds to form a resist underlayer film having an average thickness of 200 nm, and the resist underlayer film was formed on the substrate. A substrate with a resist underlayer film was obtained. Observe the resist underlayer film on the substrate with the resist underlayer film obtained above with an optical microscope. If no coating unevenness is observed, the coating property is “A” (good). It was evaluated as "B" (poor).

[Storage stability]
The above-prepared composition for forming a resist underlayer film was coated on a silicon wafer (substrate) by the spin coating method under the conditions of 1,500 rpm and 30 seconds using the above-mentioned spin coater. Was heated at 90 ° C. for 60 seconds to form a resist underlayer film. The case of the composition for forming a resist underlayer film (T = 0) on the day prepared above is referred to as “resist underlayer film (a0)” and the composition prepared for forming a resist underlayer film prepared above at 35 ° C. for 60 days ( in the case of T = 60) and "resist underlayer film (a1)", the average thickness of the resist underlayer film (a0) and _{T 0,} when the average thickness of the resist underlayer film (a1) was _{T 1,} the thickness variation The rate (%) was determined by the following equation and used as an index of storage stability.
Film thickness change rate (%) = | T ₁ −T ₀ | × 100 / T ₀
The storage stability is “A” (good) when the film thickness change rate is less than 1.0%, and “B” (somewhat poor) when the film thickness change rate is 1.0% or more and less than 2.0%. When it was 0% or more, it was evaluated as "C" (defective).

  As can be seen from the results in Table 2, the compositions for forming a resist underlayer film of Examples are excellent in coatability and storage stability.

<Preparation of composition for forming resist film>
[Synthesis of Compound]
Compounds (M-1) to (M-4) used for preparing the composition for forming a resist film were synthesized by the following procedure.

[Synthesis Example 2-1] (Synthesis of Compound (M-1))
In a reaction vessel, while stirring 150 mL of a 0.5 N aqueous sodium hydroxide solution, 6.5 g of isopropyltin trichloride was added, and the reaction was carried out for 2 hours. The deposited precipitate was collected by filtration, washed twice with 50 g of water, and then dried to obtain Compound (M-1). Compound (M-1) has a structure of an oxidized hydroxide product of a hydrolyzate of isopropyltin trichloride (i-PrSnO _{(3 / 2-x / 2)} (OH) _x (0 <x <3)). Unit).

[Synthesis Example 2-2] (Synthesis of Compound (M-2))
In a reaction vessel, 3.16 g of benzyltin trichloride was added while stirring 100 mL of a 0.5 M aqueous solution of tetramethylammonium hydroxide, and the reaction was carried out for 2 hours. The deposited precipitate was collected by filtration, washed twice with 50 g of water, and then dried to obtain a compound (M-2). Compound (M-12) is a compound having a structural unit represented by ((PhCH ₂ ) SnO _3/2 ).

[Synthesis Example 2-3] (Synthesis of Compound (M-3))
In a reaction vessel, 20.0 g of tetrabutoxy tin (IV), 100 g of tetrahydrofuran and 100 g of methacrylic acid were added, and the reaction was carried out at 65 ° C for 20 minutes. Next, 10.6 g of water was added dropwise over 10 minutes, and the reaction was carried out at 65 ° C. for 18 hours. Then, 10.6 g of water was added dropwise over 10 minutes, and the mixture was stirred for 2 hours. 400 g of water was added to the cooled reaction solution to obtain a precipitate. After the obtained precipitate was centrifuged, the precipitate was dissolved in 50 g of acetone, and 400 g of water was added to obtain a precipitate. The obtained precipitate was centrifuged and then dried to obtain a compound (M-3). The compound (M-3) is a particle mainly containing a metal oxide of tin and containing methacrylic acid.

[Synthesis Example 2-4] (Synthesis of Compound (M-4))
In the reaction vessel, 20.0 g of tetraisopropoxyzirconium (IV), 100 g of tetrahydrofuran and 100 g of methacrylic acid were added, and the reaction was carried out at 65 ° C. for 20 minutes. Next, 10.6 g of water was added dropwise over 10 minutes, and the reaction was carried out at 65 ° C. for 18 hours. Then, 10.6 g of water was added dropwise over 10 minutes, and the mixture was stirred for 2 hours. 400 g of water was added to the cooled reaction solution to obtain a precipitate. After the obtained precipitate was centrifuged, the precipitate was dissolved in 50 g of acetone, and 400 g of water was added to obtain a precipitate. The obtained precipitate was centrifuged and then dried to obtain a compound (M-4). The compound (M-4) is a particle mainly containing a metal oxide of zirconium and containing methacrylic acid.

[Preparation of composition for forming resist film]
[Preparation Example 2-1]
2 parts by mass of the compound (M-1) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the resulting mixture was subjected to activated 4Å molecular sieves to remove residual water. The mixture was filtered with a filter to prepare a resist film-forming composition (K-1).

[Preparation Example 2-2]
2 parts by mass of the compound (M-2) synthesized above and 98 parts by mass of propylene glycol monoethyl ether were mixed, and the obtained solution was filtered through a filter having a pore size of 0.2 μm to obtain a composition for forming a resist film ( K-2) was prepared.

[Preparation Example 2-3]
2 parts by mass of the compound (M-3) synthesized above, 98 parts by mass of propylene glycol monoethyl ether, and 0.2 parts by mass of N-trifluoromethanesulfonyloxy-5-norbornene-2,3-dicarboximide are mixed. The resulting solution was filtered through a filter having a pore size of 0.2 μm to prepare a resist film forming composition (K-3).

[Preparation Example 2-4]
A mixture of 2 parts by mass of the compound (M-4) synthesized above, 98 parts by mass of propylene glycol monoethyl ether, and 0.2 parts by mass of N-trifluoromethanesulfonyloxy-5-norbornene-2,3-dicarboximide is mixed. Then, the obtained solution was filtered through a filter having a pore size of 0.2 μm to prepare a resist film forming composition (K-4).

<Evaluation>
[Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-8]
With respect to the composition for forming a resist underlayer film prepared above, the resist sensitivity change suppressing property was evaluated by using the composition for forming a resist film prepared above according to the following method. Table 3 shows the evaluation results for each of the electron beam exposure and the extreme ultraviolet exposure. "-" In Table 3 indicates that the corresponding evaluation was not performed.

[Resistant sensitivity change suppressing property] (Sensitivity change suppressing property of resist film forming composition by electron beam exposure)
The composition for forming a resist underlayer film shown in the following Table 3 was coated on an 8-inch silicon wafer by a spin coating method using a spin coater (“CLEAN TRACK ACT8” of Tokyo Electron Ltd.), and then at 250 ° C. for 60 seconds. By heating, a resist underlayer film having an average thickness of 100 nm was formed. On the resist underlayer film, a composition for forming a resist film shown in Table 3 below was applied by a spin coating method using the spin coater, and after a predetermined time, heated at 90 ° C. for 60 seconds, By cooling at 23 ° C. for 30 seconds, a resist film having an average thickness of 35 nm was formed. As the resist film, a “resist film (b0)” when the predetermined time was set to 30 seconds and a “resist film (b1)” when the predetermined time was set to 300 seconds were formed.

The resist film was irradiated with an electron beam using an electron beam lithography system (“HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 amps / cm ² ). After the electron beam irradiation, the substrate was heated at 110 ° C. for 60 seconds, then cooled at 23 ° C. for 60 seconds, and then developed using a 2.38 mass% TMAH aqueous solution (20 to 25 ° C.) by a paddle method. After washing with water and drying, an evaluation substrate on which a resist pattern was formed was obtained.

A scanning electron microscope ("S9380" manufactured by Hitachi High-Technologies Corporation) was used for measuring the length of the resist pattern on the evaluation substrate. In the above-mentioned evaluation substrate, the exposure amount at which a one-to-one line and space having a line width of 100 nm is formed is defined as the optimum exposure amount, and the optimum exposure amount on the evaluation substrate having the resist film (b0) is D ₀ , when the optimal exposure amount in evaluation substrate having b1) was D _1, the optimum exposure amount change rate (%) was determined according to the following equation, and the resist sensitivity variation inhibitory index.
Optimal exposure dose change rate (%) = | D ₁ −D ₀ | × 100 / D ₀
The resist sensitivity change suppression property was evaluated as “A” (good) when the optimum exposure dose change rate was less than 1%, and “B” (bad) when the optimum exposure dose change rate was 1% or more.

[Resistant sensitivity change suppression] (Sensitivity change suppression of resist film forming composition by extreme ultraviolet exposure)
A composition for forming a resist underlayer film shown in Table 3 below was coated on a 12-inch silicon wafer by a spin coating method using a spin coater (“CLEAN TRACK ACT12” of Tokyo Electron Ltd.), and then at 250 ° C. for 60 seconds. By heating, a resist underlayer film having an average thickness of 100 nm was formed. On the resist underlayer film, a composition for forming a resist film shown in Table 3 below was applied by a spin coating method using the spin coater, and after a predetermined time, heated at 90 ° C. for 60 seconds, By cooling at 23 ° C. for 30 seconds, a resist film having an average thickness of 35 nm was formed. As the resist film, a “resist film (c0)” when the predetermined time was set to 30 seconds and a “resist film (c1)” when the predetermined time was set to 300 seconds were formed.

  Exposure to the resist film using an EUV scanner ("TWINSCAN NXE: 3300B" from ASML (NA0.3, Sigma0.9, Quadrupole illumination, 1: 1 line-and-space mask with a line width of 25 nm on the wafer)) After the exposure, the substrate was heated at 110 ° C. for 60 seconds, and then cooled at 23 ° C. for 60 seconds, and then developed by a paddle method using a 2.38% by mass aqueous TMAH solution (20 to 25 ° C.). Thereafter, the substrate was washed with water and dried to obtain an evaluation substrate on which a resist pattern was formed.

A scanning electron microscope (“CG-4000” manufactured by Hitachi High-Technologies Corporation) was used for length measurement and observation of the resist pattern on the evaluation substrate. In the above-mentioned evaluation substrate, the exposure amount at which a one-to-one line-and-space having a line width of 25 nm is formed is set as the optimum exposure amount, and the optimum exposure amount on the evaluation substrate having the resist film (c0) is D ₀ , when the optimal exposure amount in evaluation board having c1) was D _1, the optimum exposure amount change rate (%) was determined according to the following equation, and the resist sensitivity variation inhibitory index.
Optimal exposure dose change rate (%) = | D ₁ −D ₀ | × 100 / D ₀
The resist sensitivity change suppression property was evaluated as “A” (good) when the optimum exposure dose change rate was less than 1%, and “B” (bad) when the optimum exposure dose change rate was 1% or more.

  As can be seen from the results in Table 3, the compositions for forming a resist underlayer film of Examples can form a resist underlayer film excellent in resist sensitivity change suppression.

The composition for forming a resist underlayer film of the present invention is excellent in coating properties, storage stability and resist sensitivity change suppressing properties. Since the resist underlayer film of the present invention is formed from the composition for forming a resist underlayer film, the resist underlayer film is excellent in resist sensitivity change suppression. According to the method of forming a resist pattern of the present invention, a resist underlayer film excellent in resist sensitivity change suppression properties can be formed, and a good resist pattern can be formed by using this resist underlayer film. Therefore, they can be suitably used for the manufacture of semiconductor devices, which are expected to be further miniaturized in the future.

Claims (7)

A compound having an aromatic ring,
An organic solvent,
Contains water and
A composition for forming a resist underlayer film, wherein the water content is 0.5% by mass or more and 15% by mass or less.   The composition for forming a resist underlayer film according to claim 1, wherein the compound having an aromatic ring is a polymer having a structural unit containing an aromatic ring.   The resist according to claim 2, wherein the polymer having a structural unit containing an aromatic ring is a novolak resin, a resol resin, a styrene resin, an acenaphthylene resin, an indene resin, an arylene resin, a triazine resin, a calixarene resin, or a combination thereof. A composition for forming an underlayer film.   4. The composition for forming a resist underlayer film according to claim 1, wherein the compound having an aromatic ring has a hydroxyl group. 5.   The composition for forming a resist underlayer film according to any one of claims 1 to 4, wherein the content of the water is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the compound having an aromatic ring.   A resist underlayer film formed from the composition for forming a resist underlayer film according to claim 1. A step of coating the composition for forming a resist underlayer film according to any one of claims 1 to 5 on one surface side of the substrate,
Heating the coating film formed by the resist underlayer film forming composition coating process,
A step of applying a composition for forming a resist film on the side of the resist underlayer film formed by the heating step opposite to the substrate,
Exposing the resist film formed by the resist film forming composition coating step with radiation,
Developing the exposed resist film.