JP2012203393A - Composition for forming resist underlayer film, resist underlayer film, and pattern formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition capable of forming a resist underlayer film having a high refractive index and an absorbancy index and having high etching selectivity to a resist film in dry etching, and to provide a resist underlayer film to be formed and a pattern formation method using the composition.SOLUTION: (A) The composition for forming a resist underlayer film includes a polymer including a structural unit (I) derived from a compound represented by following formula (1). (In the formula (1), Rand Rare an organic group each independently including hydrogen atoms, halogen atoms, a hydrocarbon group with the carbon number of 1 to 20, or an epoxy group. Ris -CO- or CRR. Rand Rare each independently hydrogen atoms, halogen atoms, a hydroxyl group, and a hydrocarbon group with the carbon number of 1 to 10. Where, a part or all of hydrogen atoms of the hydrocarbon group may be substituted.)

Description

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

  Conventionally, in the manufacture of semiconductor devices, fine processing by lithography using a photoresist composition has been performed. In recent years, the degree of integration of semiconductor devices has increased, and the actinic rays used have also been shortened from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). A method of providing a resist underlayer film such as an antireflection film between the photoresist and the substrate because irregular reflection of actinic rays from the substrate greatly affects pattern formation as the pattern becomes finer with shorter wavelengths Is being considered. In addition, when the actinic ray is EUV (13.5 nm), the actinic ray is transmitted through the substrate, so that the influence of irregular reflection is small, but the photoresist is thinned, so that the etching selectivity with the photoresist is high. Necessary.

  Known compositions for forming a resist underlayer film include inorganic compositions containing titanium, titanium dioxide, titanium nitride, and the like, and organic compositions containing a light-absorbing substance and a polymer compound. The inorganic composition requires an equipment such as a vacuum deposition apparatus, a CVD apparatus, and a sputtering apparatus for forming the lower layer film, whereas the organic composition is advantageous in that no special equipment is required. Examples of the organic composition include an acrylic resin-type composition having a hydroxyl group and a light absorbing group that are cross-linking reactive groups in the same molecule (see US Pat. No. 5,919,599), and a hydroxyl group and a light absorbing group in the same molecule. Novolak resin-type compositions (see US Pat. No. 5,693,691) and the like are known.

  Physical properties desired for such an organic composition include a high refractive index and absorption coefficient for light and radiation, a high etching selectivity for a resist film during dry etching, and an interface with the resist film. Mixing does not occur (insoluble in the resist composition), etc. (see Proc. SPIE, Vol. 3678, 174-185 (1999) and Proc. SPIE, Vol. 3678, 800-809 (1999)). .

  Currently, further miniaturization is being studied in the manufacturing process of semiconductor devices, and the development of a composition for forming a resist underlayer film that is superior in the above characteristics is desired.

US Pat. No. 5,919,599 US Pat. No. 5,693,691

Proc. SPIE, Vol. 3678 (1999), p. 174-185 Proc. SPIE, Vol. 3678 (1999), p. 800-809

  The present invention has been made based on the above circumstances, and its purpose is to form a resist underlayer film having a high refractive index and an extinction coefficient and having a high etching selectivity with respect to a resist film during dry etching. A resist underlayer film formed from the composition, and a pattern forming method using the composition.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立して水素原子、ハロゲン原子、炭素数１〜２０の炭化水素基又はエポキシ基を有する有機基である。Ｒ^３は、−ＣＯ−又はＣＲ^４Ｒ^５である。Ｒ^４及びＲ^５は、それぞれ独立して水素原子、ハロゲン原子、水酸基、炭素数１〜１０の炭化水素基である。但し、上記炭化水素基は、水素原子の一部又は全部が置換されていてもよい。） The invention made to solve the above problems is
[A] A resist underlayer film forming composition containing a polymer containing a structural unit (I) derived from a compound represented by the following formula (1) (hereinafter also referred to as “[A] polymer”). .

(In Formula (1), R ¹ and R ² are each independently an organic group having a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or an epoxy group. R ³ is —CO—. Or CR ⁴ R ^5. R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms, provided that the hydrocarbon group is a hydrogen atom Part or all may be substituted.)

  The composition for forming a resist underlayer film of the present invention contains a [A] polymer containing the structural unit (I) so that it has a high refractive index and an extinction coefficient, and is highly etched with respect to the resist film during dry etching. A resist underlayer film having selectivity can be formed.

At least one of R ¹ and R ² is preferably a glycidyl group. By making at least one of R ¹ and R ² a glycidyl group, the structural unit (I) can be more easily introduced into the [A] polymer.

  It is preferable that the composition further contains [B] a crosslinking agent. When the composition further contains a [B] cross-linking agent, a cross-linking reaction between the [B] cross-linking agent and the [A] polymer occurs, and intermixing between the resist underlayer film to be formed and the resist composition is suppressed. Is done.

The pattern forming method of the present invention comprises:
(1) A step of applying the composition onto a substrate to be processed to form a resist underlayer film,
(2) A step of applying a resist composition on the resist underlayer film to form a resist film,
(3) a step of exposing the resist film by irradiating with radiation through the resist film mask;
(4) developing the exposed resist film to form a resist pattern; and (5) forming a pattern by dry etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. .

  According to the pattern formation method, it is possible to efficiently form a resist underlayer film having a high refractive index and an extinction coefficient and having high etching selectivity with respect to the resist film during dry etching. Therefore, the present invention can be suitably applied to a semiconductor device manufacturing process that is further miniaturized.

  The present invention also includes a resist underlayer film formed from the composition.

  The present invention provides a composition capable of forming a resist underlayer film having a high refractive index and an extinction coefficient and having a high etching selectivity for a resist film during dry etching, a resist underlayer film formed from the composition, and the composition A pattern forming method using an object can be provided. Therefore, the present invention can be suitably applied to a semiconductor device manufacturing process that is further miniaturized.

<Composition for forming resist underlayer film>
The composition contains a [A] polymer. Moreover, you may contain a [B] crosslinking agent and a [C] crosslinking catalyst as a suitable component. Furthermore, the said composition may contain another arbitrary component, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
The composition for forming a resist underlayer film of the present invention contains a [A] polymer containing the structural unit (I) so that it has a high refractive index and an extinction coefficient, and is highly etched with respect to the resist film during dry etching. A resist underlayer film having selectivity can be formed.

[Structural unit (I)]
[A] The polymer is a polymer containing the structural unit (I) derived from the compound represented by the formula (1).

In the above formula (1), R ¹ and R ² are each independently an organic group having a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or an epoxy group. R ³ is —CO— or CR ⁴ R ⁵ . R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms. However, part or all of the hydrogen atoms in the hydrocarbon group may be substituted.

Examples of the halogen atom represented by R ¹ and R ² include a fluorine atom, a chlorine atom, and a bromine atom.

Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ¹ and R ^2, for example, linear or branched alkyl group, a benzene derivative groups, and vinyl-induced group. Examples of the linear or branched alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl. Groups and the like. Examples of the benzene derivative group include a phenyl group, a benzyl group, a biphenyl group, and a naphthyl group. Examples of the vinyl derivative group include ethenyl group, propenyl group, butenyl group, butadienyl group and the like.

The organic group having an epoxy group represented by R ¹ and R ² is not particularly limited as long as it is an organic group having an epoxy group, and examples of the organic group include a linear or branched alkyl group. It is done. Examples of the linear or branched alkyl group having an epoxy group include a glycidyl group. The epoxy group is a concept including an oxiranyl group (1,2-epoxy structure) and an oxetanyl group (1,3-epoxy structure).

As a C1-C10 hydrocarbon group represented by said R < ⁴ > and R < ⁵ >, a linear or branched alkyl group etc. are mentioned, for example. Examples of the linear or branched alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl. Groups and the like.

  The hydrocarbon group may have some or all of the hydrogen atoms substituted, and examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group, and an acyl group.

As the monomer that gives the structural unit (I), a monomer in which at least one of R ¹ and R ² is a glycidyl group is preferable. By making at least one of R ¹ and R ² a glycidyl group, the structural unit (I) can be more easily introduced into the [A] polymer.

  Moreover, as a monomer which gives structural unit (I), the compound induced | guided | derived from the compound represented by the said Formula (1) may be sufficient. As such a compound, a compound represented by the following formula (2) is preferable.

In the formula ^(2), R 6 to R ⁹ are each independently the same meaning as that of ^{R 1} and ^{R 2} in the formula (1).

  [A] The polymer may contain two or more structural units (I). [A] As a content rate of structural unit (I) in a polymer, 30 mol%-100 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 100 mol% is more preferable. By setting the content of the structural unit (I) in the specific range, it is possible to form a resist underlayer film having a high refractive index and an extinction coefficient and having high etching selectivity with respect to the resist film during dry etching.

[Other structural units]
[A] The polymer may contain other structural units other than the structural unit (I) as long as the effects of the present invention are not impaired.

<[A] Polymer Synthesis Method>
[A] As a method for synthesizing the polymer, for example, when the monomer giving the structural unit (I) has a radical polymerizable group, it can be synthesized by polymerization in an appropriate solvent using a polymerization initiator. Moreover, when the monomer which gives structural unit (I) has crosslinkable groups, such as an epoxy group, it can superpose | polymerize in presence of a crosslinking agent, a crosslinking catalyst, etc. preferably. As a crosslinking agent and a crosslinking catalyst, the compound etc. which are illustrated as a [B] crosslinking agent and a [C] crosslinking catalyst mentioned later, for example are mentioned.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2′-azobis (2-cyclopropyl). Propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylpropionitrile), dimethyl 2,2-azobisisobutyrate and the like. These initiators can be used alone or in combination of two or more.

  The polymerization solvent is not particularly limited as long as radical polymerization is performed as long as it is a solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, or the like). When the polymerization is performed under a crosslinking agent and a crosslinking catalyst, the type of the solvent is not particularly limited. Examples of the polymerization solvent include alcohol solvents, ketone solvents, amide solvents, ester / lactone solvents, nitrile solvents, and mixed solvents thereof. These solvents can be used alone or in combination of two or more.

  The [A] polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the target [A] polymer is recovered as a powder by putting the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in combination of two or more. In addition to the reprecipitation method, low molecular components such as monomers and oligomers can be removed by a liquid separation operation, a column operation, an ultrafiltration operation, or the like, and the [A] polymer can be recovered.

  The reaction temperature in these synthesis methods is appropriately determined depending on the monomer giving the structural unit (I), the type of polymerization initiator used, and the like.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 500 to 100,000, more preferably 1,000 to 50,000. [A] When the Mw of the polymer is less than 500, the intermixing resistance of the lower layer film may be lowered. On the other hand, when Mw exceeds 100,000, the in-plane uniformity of the lower layer film tends to decrease.

  In addition, Mw of this specification uses GPC column (The Tosoh make, G2000HXL 2 pieces, G2000HXL 2 pieces, G3000HXL 1 piece, G4000HXL 1 piece), flow rate 1.0mL / min, elution solvent tetrahydrofuran, column temperature of 40 degreeC It means a value measured by GPC using monodisperse polystyrene as a standard under analysis conditions. [A] The ratio (Mw / Mn) of the polymer Mw to the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is usually 1 to 5, preferably 1 to 3.0.

<[B] Crosslinking agent>
[B] The crosslinking agent that may be contained as a suitable component in the composition is a compound that forms a bond with a compounded composition such as a resin or other crosslinking agent molecules by the action of heat or acid. [B] Examples of the crosslinking agent include polyfunctional (meth) acrylate compounds, epoxy compounds, hydroxymethyl group-substituted phenol compounds, and compounds having an alkoxyalkylated amino group. [B] A crosslinking agent can be used alone or in combination of two or more.

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

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

  Examples of the hydroxymethyl group-substituted phenol compound include 2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene, 3,5-dihydroxymethyl-4-methoxytoluene [2,6- Bis (hydroxymethyl) -p-cresol] and the like.

  Examples of the compound having an alkoxyalkylated amino group include a plurality of compounds in one molecule such as (poly) methylolated melamine, (poly) methylolated glycoluril, (poly) methylolated benzoguanamine, and (poly) methylolated urea. A nitrogen-containing compound having one active methylol group, wherein at least one hydrogen atom of the hydroxyl group of the methylol group is substituted with an alkyl group such as a methyl group or a butyl group. The compound having an alkoxyalkylated amino group may be a mixture in which a plurality of substituted compounds are mixed, or may include an oligomer component that is partially self-condensed.

  Of these, compounds having an alkoxyalkylated amino group are preferred, and methylolated melamine and methylolated glycoluril are more preferred.

  [B] The content ratio of the crosslinking agent is appropriately set so that the lower layer film formed from the composition is sufficiently cured, and is contained in 100% by mass of the polymer [A] contained in the composition. (However, when the polymer other than the polymer [A] is further contained, it is usually 0.1 parts by weight to 50 parts by weight, preferably 1 part by weight with respect to 100 parts by weight of the whole polymer). Part to 30 parts by mass. [B] If the content of the crosslinking agent is less than 0.1 parts by mass, the resulting resist underlayer film may have insufficient hardness. On the other hand, when the content ratio of [B] cross-linking agent exceeds 50 parts by mass, a cross-linking reaction may occur between the cross-linking agent in the lower layer film and the resist.

<[C] Cross-linking catalyst>
The composition [C] cross-linking catalyst that the composition may contain as a suitable component is a component that promotes cross-linking of the polymer [A], and as a result, the composition contains the [C] cross-linking catalyst. A resist underlayer film having a high refractive index can be formed.

  [C] Examples of the crosslinking catalyst include amine compounds, phenol resins, amino resins, mercaptan compounds, hydrazides, polyphenols, polybasic acids, light or thermal acid generators, and the like. Among these, a light or thermal acid generator that has little influence on productivity and optical characteristics of the remaining catalyst is preferable.

  [C] The content ratio of the crosslinking catalyst is appropriately set so that the lower layer film formed from the composition is sufficiently cured, and is contained in the composition with respect to 100 parts by mass of the polymer (A). (However, when the polymer other than the polymer [A] is further contained, it is generally 0.1 to 15 parts by mass, preferably 0. 1 part by mass to 10 parts by mass. [C] If the content of the crosslinking catalyst is less than 0.1 parts by mass, the resulting resist underlayer film may have insufficient hardness. On the other hand, when the content of the [C] crosslinking catalyst exceeds 15 parts by mass, a crosslinking reaction may occur between the crosslinking agent in the lower layer film and the resist.

<[D] solvent>
The composition usually contains a [D] solvent. [D] Examples of the solvent include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and mixed solvents thereof. These solvents can be used alone or in combination of two or more.

Examples of alcohol solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol , Sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec -Monoalcohol solvents such as heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- Ketones such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone A solvent is mentioned.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, acetic acid. n-pentyl, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, acetoacetate Ethyl acetate ethylene glycol monomethyl ether, acetate ethylene glycol monoethyl ether, acetate diethylene glycol monomethyl ether, acetate diethylene glycol monoethyl ether, acetate diethylene glycol mono-n-butyl Ether ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriacetate Glycol, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, Examples thereof include dimethyl phthalate and diethyl phthalate.

Examples of other solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents;
And halogen-containing solvents such as dichloromethane, chloroform, chlorofluorocarbon, chlorobenzene, and dichlorobenzene.

  Of these [D] solvents, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, and cyclohexanone are preferred.

<Other optional components>
The said composition can contain other arbitrary components, such as surfactant, in the range which does not impair the effect of this invention. These other optional components can be used alone or in combination of two or more. Moreover, the compounding quantity of another arbitrary component can be suitably determined according to the objective.

[Surfactant]
The surfactant can be added to improve the coating property of the composition, reduce coating unevenness, and improve the developability of the radiation irradiated part. Examples of preferable surfactants include nonionic surfactants, fluorosurfactants, and silicone surfactants.
Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. In addition to nonionic surfactants such as stearate, the following trade names are KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFac F171, F173 (above, manufactured by Dainippon Ink & Chemicals), Fluorad FC430, FC431 ( As above, manufactured by Sumitomo 3M, Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass) ) And the like.

<Method for preparing resist underlayer film forming composition>
The composition can be prepared, for example, by mixing the [A] polymer, the [B] cross-linking agent, and other optional components as required in a predetermined ratio in the solvent. The solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer, [B] cross-linking agent and the like. The composition is usually prepared by dissolving in a solvent when used and then filtering with a filter having a pore size of about 0.1 μm, for example.

<Pattern formation method>
The pattern forming method of the present invention comprises:
(1) A step of applying the composition onto a substrate to be processed to form a resist underlayer film,
(2) A step of applying a resist composition on the resist underlayer film to form a resist film,
(3) a step of exposing the resist film by irradiating with radiation through the resist film mask;
(4) developing the exposed resist film to form a resist pattern; and (5) forming a pattern by dry etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. .

  According to the pattern formation method, it is possible to efficiently form a resist underlayer film having a high refractive index and an extinction coefficient and having high etching selectivity with respect to the resist film during dry etching. Therefore, the present invention can be suitably applied to a semiconductor device manufacturing process that is further miniaturized. Hereinafter, each process is explained in full detail.

[Step (1)]
In this step, a resist underlayer film is formed on the substrate to be processed using the composition. Examples of the substrate to be processed include insulating films such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane, and commercially available products such as black diamond (manufactured by AMAT), silk (manufactured by Dow Chemical), LKD5109 (manufactured by JSR), and the like. An interlayer insulating film such as a wafer coated with a low dielectric insulating film. As the substrate to be processed, a patterned substrate such as a wiring course (trench) or a plug groove (via) may be used.

  As a method for forming the resist underlayer film, for example, a coating film of the composition is formed by coating on the surface of a substrate to be processed or other underlayer film, and the coating film is heat-treated or irradiated with ultraviolet light. And it can form by making it harden | cure by heat-processing. Examples of the method for applying the resist underlayer film forming composition include spin coating, roll coating, and dipping. Moreover, as heating temperature, it is 50 to 450 degreeC normally. The heating time is usually 30 seconds to 1,200 seconds, preferably 45 seconds to 600 seconds.

Further, another lower layer film (hereinafter referred to as “other lower layer film”) different from the resist lower layer film obtained by using the composition for forming a resist lower layer film of the present invention in advance is formed on the substrate to be processed. It may be. The other lower layer film is a film provided with an antireflection function, coating film flatness, high etching resistance against a fluorine-based gas such as CF _{4, and the} like. As other lower layer films, for example, commercially available products such as NFC HM8005 (manufactured by JSR) and NFC CT08 (manufactured by JSR) can be used.

  The film thickness of the resist underlayer film is usually 5 nm or more and 200 nm or less, and preferably 10 nm or more and 100 nm or less in order to improve the patterning property.

[Steps (2) to (4)]
In this step, a resist composition is applied to the upper surface side of the resist underlayer film, exposed, heated and developed to form a resist pattern. Examples of the resist composition include a positive or negative chemically amplified resist composition containing a photoacid generator, a positive resist composition comprising an alkali-soluble resin and a quinonediazide-based photosensitizer, and an alkali-soluble resin and a cross-link. And negative resist compositions composed of an agent. In addition, in the pattern formation method of this invention, a commercially available resist composition can also be used as such a resist composition. As a method of applying the resist composition, it can be applied by a conventional method such as a spin coating method. In addition, when apply | coating a resist composition, the quantity of the resist composition to apply | coat is adjusted so that the resist coating film obtained may become a desired film thickness. The method for applying the resist composition is not particularly limited, and can be applied by a conventional method such as a spin coating method.

  The resist coating film is formed by volatilizing a solvent (that is, a solvent contained in the resist composition) in the coating film by pre-baking the coating film formed by applying the resist composition. Can do. The pre-baking temperature is appropriately adjusted according to the type of resist composition to be used, but is preferably 50 ° C to 200 ° C, more preferably 80 ° C to 150 ° C. The heating time is usually 30 seconds to 200 seconds, preferably 45 seconds to 120 seconds. In addition, you may provide another coating film on the surface of this resist film. The thickness of the resist film is usually 0.01 μm to 0.5 μm, and preferably 0.02 μm to 0.3 μm.

Next, the resulting resist coating film is selectively irradiated with radiation through a photomask to expose the resist coating film. The radiation is appropriately selected from visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, γ-ray, molecular beam, ion beam, etc., depending on the type of acid generator used in the resist composition. Is preferably a deep ultraviolet ray, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (wavelength 157 nm), Kr ₂ excimer laser (wavelength 147 nm), ArKr excimer laser (wavelength 134 nm), Extreme ultraviolet rays (wavelength 13 nm or the like) are more preferable. Further, an immersion exposure method can also be employed.

  After the exposure, post-baking is performed in order to improve the resolution, pattern profile, developability, and the like of the resist film. The post-baking temperature is appropriately adjusted according to the type of resist composition used. The heating time is usually 30 seconds to 200 seconds, preferably 45 seconds to 120 seconds.

  After the post-baking, the resist coating film is developed to form a resist pattern. The developer used for development can be appropriately selected depending on the type of resist composition used. In the case of a positive chemically amplified resist composition or a positive resist composition containing an alkali-soluble resin, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n- Propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5. 4.0] -7-undecene and 1,5-diazabicyclo [4.3.0] -5-nonene. These alkaline aqueous solutions may be those obtained by adding an appropriate amount of a water-soluble organic solvent, for example, alcohols such as methanol and ethanol, and a surfactant.

  Further, in the case of a negative chemically amplified resist composition and a negative resist composition containing an alkali-soluble resin, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, etc. Inorganic alkalis, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, dimethylethanolamine and triethanolamine Alcohol amines, tetramethylammonium hydroxide, tetraethylammonium hydroxide, quaternary ammonium salts such as choline, and alkaline aqueous solutions such as pyrrole, piperidine and other cyclic amines.

[Step (5)]
In this step, the resist underlayer film and the substrate to be processed are dry-etched using the resist pattern as a mask. Dry etching can be performed using a known dry etching apparatus. The source gas during dry etching depends on the elemental composition of the object to be etched, but includes oxygen atoms such as O ₂ , CO, and CO ₂ , inert gases such as He, N ₂ , and Ar, Cl ₂ , chlorine gas such as BCl ₄ , fluorine gas such as CHF ₃ and CF ₄ , gas of H ₂ and NH ₃ , etc. can be used. In addition, these gases can also be mixed and used.

  Moreover, you may have the process of removing the resist underlayer film which remain | survives on a to-be-processed substrate after these processes.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

<[A] Synthesis of polymer>
[Synthesis Example 1]
To a glass flask equipped with a thermometer and a condenser were added 10.0 g (78.7 mmol) of barbituric acid, 72.8 g (787 mmol) of epichlorohydrin and 248 mg (1.18 mmol) of tetraethylammonium bromide. Heated for hours. Thereafter, 32.6 g (236.1 mmol) of potassium carbonate and 40 mL of acetonitrile were added, and the mixture was further refluxed for 6 hours. After the reaction, low-boiling components were distilled off under reduced pressure, and the remaining solid was washed with acetonitrile to obtain a crude product (a-1) represented by the following formula (45.2 g). Chemical shifts analyzed using ¹ H-NMR (JNM-GX400, manufactured by JEOL Ltd.) are shown below.

¹ H-NMR (DMSO-d ₆ ) δ (ppm): 3.94 (4H), 3.70 (2H), 3.17 (2H), 2.75 (2H), 2.56 (2H)

  To a glass flask equipped with a thermometer and a condenser were added 15 g of the crude product (a-1), 1.23 g (13.1 mmol) of phenol, 214 mg (0.787 mmol) of benzyltriethylammonium chloride and 200 mL of xylene. The reaction was carried out at ° C for 14 hours. After the reaction, the reaction solution was cooled to room temperature and poured into 500 mL of water. The precipitated solid was collected by filtration, further washed twice with 100 mL of water, and then dried under reduced pressure at 50 ° C. for 17 hours to obtain a polymer (A-1) (yield 0.48 g). The polymer (A-1) had Mw of 1,850 and Mw / Mn of 2.4.

[Synthesis Example 2]
In a 200 mL flask, 17.7 g (40 mol%) of 2-hydroxy methacrylate, 32.3 g (60 mol%) of benzyl methacrylate, 2.11 g of dimethyl 2,2′-azobis (2-methylpropionate) and 100 g of methyl ethyl ketone. And stirred for 5 hours at 80 ° C. under nitrogen to conduct a polymerization reaction. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling, and then poured into 250 g of methanol to precipitate the polymer. After removing the supernatant solution, 100 g of methanol was added to the precipitated polymer to wash the polymer. After removing the supernatant, it was dried at 50 ° C. for 17 hours to obtain a polymer (CA-1) (yield 31 g, yield 61%). The polymer (CA-1) had Mw of 15,200 and Mw / Mn of 2.3.

<Preparation of composition for forming resist underlayer film>
[A] The [B] cross-linking agent, [C] cross-linking catalyst, and [D] solvent used for the preparation of the composition for forming the lower layer film other than the polymer are shown below.

[B] Crosslinking agent B-1: Compound represented by the following formula (B-1) B-2: Compound represented by the following formula (B-2)

[C] Cross-linking catalyst C-1: Compound represented by the following formula (C-1)

[D] Solvent D-1: Ethyl lactate

[Example 1]
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as a crosslinking agent, [C] 3 parts by mass of (C-1) as a crosslinking catalyst, and [D A composition for forming a resist underlayer film was prepared by mixing 3,500 parts by mass of (D-1) as a solvent.

[Example 2 and Comparative Examples 1-2]
Each resist underlayer film forming composition was prepared in the same manner as in Example 1 except that the types and amounts of each component shown in Table 1 were used.

<Synthesis of polymer for resist composition>
The compounds (M-1) to (M-4) used for the synthesis of the polymer used for preparing the resist composition are shown below.

[Synthesis Example 3]
18.60 g (15 mol%) of the compound (M-1), 6.20 g (35 mol%) of the compound (M-2) and 25.20 g (50 mol%) of the compound (M-4) were added to 100 g of 2-butanone. A monomer solution in which 1.86 g of dimethyl 2,2′-azobis (2-methylpropionate) was dissolved was prepared. A 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution prepared as described above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, and poured into 1,000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was dispersed in 200 g of methanol, washed in the form of a slurry, and then filtered off twice. The white powder copolymer (R-1) was obtained by drying at 50 ° C. for 17 hours (yield 39 g, yield 78%). The copolymer (R-1) had Mw of 6,300 and Mw / Mn of 1.4.

[Synthesis Example 4]
17.69 g (40 mol%) of the compound (M-1), 5.35 g (10 mol%) of the compound (M-3) and 26.96 g (50 mol%) of the compound (M-4) were added to 100 g of 2-butanone. A monomer solution in which 1.99 g of dimethyl 2,2′-azobis (2-methylpropionate) was dissolved was prepared. A 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution prepared as described above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, and poured into 1,000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was dispersed in 200 g of methanol, washed in the form of a slurry, and then filtered off twice. The white powder copolymer (R-2) was obtained by drying at 50 ° C. for 17 hours (yield 41 g, yield 82%). The copolymer (R-2) had Mw of 6,100 and Mw / Mn of 1.4.

<Preparation of resist composition>
[Synthesis Example 5]
70 parts by mass of polymer (R-1) and 30 parts by mass of polymer (R-2), 4 parts by mass of triphenylsulfonium nonafluoro-n-butanesulfonate as an acid generator and 4-butoxy-1-naphthyltetrahydrothio 5 parts by mass of phenium nonafluoro-n-butanesulfonate, 0.9 parts by mass of Nt-amyloxycarbonyl-4-hydroxypiperidine as an acid diffusion controller, and propylene glycol monomethyl ether 1,250 as a solvent Mass parts and 520 parts by mass of cyclohexanone were mixed to prepare a resist composition (P-1).

<Formation of resist underlayer film>
Each prepared resist underlayer film forming composition is applied to the surface of an 8-inch silicon wafer by spin coating, and baked on a hot plate at 205 ° C. for 60 seconds to form a resist underlayer film having a thickness of 90 nm. did.

<Evaluation 1>
The obtained resist underlayer film was evaluated as follows. The results are shown in Table 1.

[Measurement of refractive index n and attenuation coefficient (absorption coefficient) k]
A refractive index n and an attenuation coefficient k at a wavelength of 193 nm of the resist underlayer film were measured using a spectroscopic ellipsometer.

<Formation of resist film>
The resist composition (P-1) prepared on this resist underlayer film was applied by spin coating, and baked on a hot plate at 120 ° C. for 60 seconds to form a 120 nm-thick photoresist film. At this time, no intermixing between the resist and the resist underlayer film was observed.

<Evaluation 2>
[Etching selectivity]
The resist underlayer film forming composition solutions obtained in Example 1 and Comparative Example 1 were each applied onto a silicon wafer using a spinner and baked at 205 ° C. for 1 minute on a hot plate to form resist underlayer films. did. The prepared resist composition (P-1) was applied onto a silicon wafer using a spinner and baked on a hot plate at 100 ° C. for 1 minute to form a resist film. The dry etching rate was measured under conditions using CF ₄ as the dry etching gas. The dry etching rate of the resist underlayer film when the dry etching rate of the resist film was 1 was defined as the etching selectivity.

<Formation of resist pattern>
[Example 3]
The obtained resist underlayer film forming composition and the silicon wafer coated with the resist composition were exposed through a mask pattern using an ArF excimer laser exposure apparatus (NSRS306C, manufactured by NIKON). Thereafter, post-baking was performed at 115 ° C. for 60 seconds, and then developed with a 2.38% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 30 seconds, washed with water, and dried to form a positive resist pattern. Thereafter, the silicon wafer and the resist underlayer film are etched using the resist pattern as a mask (manufactured by Tokyo Electron, conditions: silicon-based oxide film etching gas CF ₄ (CF ₄ : 150 mL / min, RF power: 300 W)), underlayer film etching gas O ₂ / N ₂ (O ₂ : 55 mL / min, N ₂ : 65 mL / min, RF power: 700 W)) was sequentially dry etched.

  As is clear from the results shown in Table 1, it is found that the resist underlayer film formed from the composition has a high refractive index and an extinction coefficient, and has a high etching selectivity with respect to the resist film during dry etching. It was. It has also been clarified that the resist underlayer film does not cause intermixing with the resist composition.

  The present invention provides a composition capable of forming a resist underlayer film having a high refractive index and an extinction coefficient and having a high etching selectivity for a resist film during dry etching, a resist underlayer film formed from the composition, and the composition A pattern forming method using an object can be provided. Therefore, the present invention can be suitably applied to a semiconductor device manufacturing process that is further miniaturized.

Claims (5)

[A] A resist underlayer film forming composition containing a polymer containing a structural unit (I) derived from a compound represented by the following formula (1).

(In Formula (1), R ¹ and R ² are each independently an organic group having a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or an epoxy group. R ³ is —CO—. Or CR ⁴ R ^5. R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 10 carbon atoms, provided that the hydrocarbon group is a hydrogen atom Part or all may be substituted.) The composition for forming a resist underlayer film according to claim 1, wherein at least one of R ¹ and R ² is a glycidyl group.   [B] The composition for forming a resist underlayer film according to claim 1 or 2, further comprising a crosslinking agent. (1) A step of applying the resist underlayer film forming composition according to claim 1, claim 2 or claim 3 on a substrate to be processed to form a resist underlayer film,
(2) A step of applying a resist composition on the resist underlayer film to form a resist film,
(3) irradiating the resist film with radiation through a mask to expose the resist film;
(4) developing the exposed resist film to form a resist pattern; and (5) forming a pattern by dry etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. Pattern forming method.   A resist underlayer film formed from the resist underlayer film forming composition according to claim 1, 2 or 3.