WO2013147315A1 - Method of forming pattern, photomask and nanoimprint mold master - Google Patents

Method of forming pattern, photomask and nanoimprint mold master Download PDF

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Publication number
WO2013147315A1
WO2013147315A1 PCT/JP2013/060142 JP2013060142W WO2013147315A1 WO 2013147315 A1 WO2013147315 A1 WO 2013147315A1 JP 2013060142 W JP2013060142 W JP 2013060142W WO 2013147315 A1 WO2013147315 A1 WO 2013147315A1
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Prior art keywords
group
pattern
carbon atoms
developer
general formula
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PCT/JP2013/060142
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French (fr)
Inventor
Toru Tsuchihashi
Toshihiro Usa
Tomokazu Seki
Ikuo Takano
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Fujifilm Corporation
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Priority to KR1020147016146A priority Critical patent/KR20140100523A/en
Publication of WO2013147315A1 publication Critical patent/WO2013147315A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F12/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F12/02—Monomers containing only one unsaturated aliphatic radical
    • C08F12/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F12/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by hetero atoms or groups containing heteroatoms
    • C08F12/22—Oxygen
    • C08F12/24—Phenols or alcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/06—Hydrocarbons
    • C08F212/08—Styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by heteroatoms or groups containing heteroatoms
    • C08F212/16—Halogens
    • C08F212/21—Bromine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by heteroatoms or groups containing heteroatoms
    • C08F212/22—Oxygen
    • C08F212/24—Phenols or alcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by heteroatoms or groups containing heteroatoms
    • C08F212/26—Nitrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/02—Alkylation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/0045—Photosensitive materials with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/0046—Photosensitive materials with perfluoro compounds, e.g. for dry lithography
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
    • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
    • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition
    • G03F7/0397—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition the macromolecular compound having an alicyclic moiety in a side chain
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/26—Processing photosensitive materials; Apparatus therefor
    • G03F7/30—Imagewise removal using liquid means
    • G03F7/32—Liquid compositions therefor, e.g. developers
    • G03F7/322—Aqueous alkaline compositions
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by heteroatoms or groups containing heteroatoms
    • C08F212/22—Oxygen

Definitions

  • EUV extreme ultraviolet
  • photoresist composition is performed in the process for manufacturing semiconductor devices, such as an IC and an LSI.
  • TMAH aqueous tetramethylammonium hydroxide
  • the present invention according to an aspect thereof is as follows.
  • each of Rn]_, RO2 an d Ro3 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, provided, that RQ3 may be bonded to Ar]_ to thereby form a ring, which RQ3 represents an alkylene group,
  • Q represents an alkyl group, a cycloalkyl group, an alicyclic group, an aromatic ring group, an amino group, an ammonium group, a mercapto group, a cyano group or an acyl group, provided that each of the alicyclic group and aromatic ring group may contain a heteroatom,
  • L]_ may be bonded to M and/or Q to thereby form a ring.
  • the obtained pattern is positive, and that the developer is an alkali developer.
  • R21 represents a hydrogen atom or a methyl group
  • a R 21 represents a bivalent aromatic ring group, each of RH, and R!3 independently represents an organic group with a carbon atom as an atom bonded to C in - (CR 1:L R 12 R 13 ) , provided that at. least two of R11, R!2 a nd R ⁇ 3 ma y be bonded to each other to thereby form a ring,
  • a nanoimprint mold master produced by a process comprising forming a pattern on a substrate in accordance with the method according to any of
  • the present invention has made it feasible to provide a method of forming a pattern in which a micropattern satisfying all of the realization of high resolution by the inhibition of pattern swell,
  • substitution or nonsubstitution are to be interpreted as including not only the alkyl groups containing no substituents (unsubstituted alkyl groups) but also the alkyl groups containing substituents (substituted alkyl groups ) .
  • the thus formed film is exposed through a given mask to actinic rays or radiation.
  • lithography In the exposure using electron beams, lithography through no mask
  • the actinic rays or radiation is not particularly limited. Examples thereof include a KrF excimer laser, an ArF excimer laser, EUV light and electron beams. EUV light and electron beams are preferred.
  • the concentration of TPAH in a developer is in the range of 1.5 to 4 mass%.
  • concentration is lower than 1.5 mass%, a prolonged period of time is required for completing the
  • a surfactant may be contained in the developer. However, a developer in which no surfactant is
  • the development time it is important for the same to be one in which the resist film in exposed areas is satisfactorily dissolved.
  • the development time is preferably in the range of 30 to 300 seconds, more preferably 30 to
  • the actinic-ray- or radiation-sensitive resin composition (hereinafter referred to as, for example, the composition according to the present invention) for use in the pattern forming method of the present invention will be described in detail below.
  • each of Roi ⁇ 02 anc ⁇ ⁇ 03 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group.
  • RQ3 may be bonded to Ar]_ to thereby form a ring, which RQ3 represents an alkylene group.
  • Y when n ⁇ 2 each independently, represents a hydrogen atom or a group leaving when acted on by an acid, provided that at least one of Y' s is a group leaving when acted on by an acid, which group is any of groups of general formula (II) below;
  • each of L]_ and L2 ⁇ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group.
  • M represents a single bond or a bivalent
  • L]_ may be bonded to M and/or Q to thereby form a ring .
  • the alkyl groups represented by RQ I to RQ 3 are, for example, alkyl groups each having up to 2 0 carbon atoms. Preferred examples. thereof are a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2 - ethylhexyl group, an octyl group and a dodecyl group.
  • RQ3 is an alkylene group
  • the alkylene group is preferably one having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group or an octylene group
  • each of RQ ⁇ , ⁇ 02 anc * ⁇ 03 independently is a hydrogen atom or an alkyl group.
  • a hydrogen atom is more preferred.
  • the (ri+1) -valent aromatic ring group represented by A ⁇ i preferably has 6 to 14 carbon atoms.
  • the alkyl groups represented by L]_ and L2 are, for example, alkyl groups each having 1 to 8 carbon atoms. As particular examples thereof, there can be mentioned a methyl group, an ethyl group, a propyl group, an n- butyl group, a sec-butyl group, a hexyl group and an octyl group.
  • cycloalkyl groups represented by and L2 are, for example, cycloalkyl groups each having 3 to
  • heteroatom-containing alicyclic group and aromatic ring group represented by Q there can be mentioned, for example, groups with a heterocyclic structure, such as thiirane, cyclothiorane, thiophene, furan, pyrrole, benzothiophene, benzofuran,
  • R21 represents a hydrogen atom or a methyl group.
  • M ll represents a single bond or a bivalent connecting group.
  • alkyl group, cycloalkyl group and aromatic ring group represented by are the same ' as set forth above in connection, with Q in general formula ( I ) .
  • the aralkyl group preferably has 6 to 20 carbon atoms, more preferably 7 to 12 carbon atoms.
  • the aralkyl group can be, for example, any of a benzyl group, a phenethyl group, a naphthylmethyl group and a naphthylethyl group.
  • adamantane ring a norbornane ring, a norbornene ring, a bicyclo [2, 2, 2] octane ring and a bicyclo [ 3 , 1 , 1 ] heptane ring.
  • an adamantane ring is most preferred.
  • a substituent may be introduced in each of these.
  • the introducible substituent there can be mentioned an alkyl group or any of the groups mentioned above as examples of the substituents that may further be introduced in the alkyl group.
  • Ra represents a hydrogen atom, an alkyl group or a group of the formula -CH2-0-Ra2 in which Ra2 represents a hydrogen atom, an alkyl group or an acyl group.
  • preferably 0 to 2 more preferably 1 or 2 and further more preferably 1.
  • R5 represents a non-acid- decomposable hydrocarbon group.
  • the content of such repeating units based on all the repeating units of the polymeric compound (A) is preferably in the range of 1 to 30 mol% more preferably 1 to 10 mol%.
  • the polymeric compound (A) may further comprise a repeating unit containing in its side chain a group (hereinafter also referred to as a "photoacid
  • the polymeric compound (A) hereinbelow is not an independent compound and is regarded as a constituent of the polymeric compound (A) according to the present invention. Namely, in an aspect of the present invention, it is preferred for the polymeric compound (A) to further comprise a repeating unit containing in its side chain a group that when exposed to actinic rays or radiation,
  • the aryl group contained in the arylsulfonium compounds is preferably an aryl group, such as a phenyl group or a naphthyl group, or a heteroaryl group, such as an indole residue or a pyrrole residue.
  • a phenyl group and an indole residue are more preferred.
  • the arylsulfonium compound contains., two or more aryl groups, the two or more aryl groups may be identical to or different from each other.
  • Preferred substituents are a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms and a linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms.
  • An alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms are most preferred.
  • the substituent may be introduced in any one of the three R20I to R 203' or alternatively may be introduced in all of the three R20I to R 203- When R201 to R 203 represent aryl groups, the substituent is preferably introduced in the- p-position of the aryl group.
  • R x and Ry independently represents an alkyl group, a 2-oxoalkyl group, an
  • Z ⁇ is as defined above in connection with general formula (ZI) .
  • R21O i- s preferably an electron withdrawing group, more preferably a cyano group or a fluoroalkyl group.
  • A represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted
  • the basic compound is preferably a nitrogen- containing organic basic compound.
  • the number of carbon atoms of the aryl group represented by R is not particularly limited. However, it is generally in the range of 6 to 20, preferably 6 to 10. In particular, a phenyl group, a naphthyl group and the like can be mentioned.
  • R' s is a hydrogen atom. Also, preferably, all R' s are not hydrogen atoms.
  • the amine compounds each containing a phenoxy group are those containing a phenoxy group at the end of the alkyl group of each of the amine compounds opposite to the nitrogen atom.
  • a substituent may be introduced in the phenoxy group.
  • the substituent is, for example, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic ester group, a sulfonic ester group, an aryl group, an aralkyl group, an acyloxy group or an aryloxy group .
  • tetrabutylammonium hydroxide Aside from these, use can be made of ammonium salts derived from the above amines ( 1 ) to ( 3 ) .
  • a molar ratio of 50 or below is preferred from the viewpoint of the inhibition of any resolution deterioration due to pattern thickening over time until baking treatment after exposure.
  • the molar ratio is more preferably in the range of 2 to 30, further more preferably 3 to 20.
  • the solvent content is regulated so that the total solid content of the composition falls within the range of 0.5 to 5 massl, preferably 0.8 to 3 mass%, more preferably 0.8 to 2 massl and further more preferably 0.8 to 1.5 mass%.
  • composition of the present invention may further contain a surfactant.
  • a surfactant is contained, the surfactant is preferably a fluorinated and/or siliconized surfactant.
  • Surfactants other than these fluorinated and/or siliconized surfactants can also be used.
  • Poly (p-hydroxystyrene ) (VP-2500, produced by Nippon Soda Co.., Ltd.) as a phenolic compound amounting to 10.0 g was dissolved in 60 g of tetrahydrofuran (THF) . Thereafter, 8.85 g of triethylamine was added to the solution and agitated in an ice water bath. The above obtained chloroether compound 2 (12.46 g) was dropped into the reaction liquid, and agitated for four hours. Thereafter, distilled water was added to the mixture, thereby terminating the reaction. THF was distilled off in vacuum, and the reaction product was dissolved in ethyl acetate.
  • THF tetrahydrofuran
  • the reaction of sulfonation can be performed with the use of a reagent selected from among chlorosulfonic acid (hydrolysis therewith) , sulfuric acid, fuming sulfuric acid, SO3, SO3 complex, sulfites and the like.
  • a reagent selected from among chlorosulfonic acid (hydrolysis therewith) , sulfuric acid, fuming sulfuric acid, SO3, SO3 complex, sulfites and the like.
  • exposure amount so as to form a 20 to 15 nm line and space pattern (lengthwise 0.5 mm, 40 drawn lines) drawn at 1.25 nm intervals.
  • the film was taken out from the electron beam lithography system and immediately baked on a hot plate under the conditions specified in
  • the film was rinsed by spraying a rinse liquid (23°C) specified in Table 3 over the wafer being rotated at 50 rpm at a flow rate of 200 ml/min for a given period of time.
  • TMAH aq. soln. of tetramethylammonium hydroxide
  • TEAH aq. soln. of tetraethylammonium hydroxide
  • TPAH aq. soln. of tetra-n-propylammonium
  • Resist patterns were formed and evaluated in accordance with the same procedure as in the EB exposure evaluation 1 above, except that substrates indicated in Table 5 were used.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Emergency Medicine (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials For Photolithography (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)

Abstract

Provided is a method of forming a pattern, including forming a film of an actinic-ray- or radiation-sensitive resin composition on a substrate, exposing the film to actinic rays or radiation and developing the exposed film with a developer to thereby obtain a fine pattern, characterized in that the actinic-ray- or radiation-sensitive resin composition comprises a polymeric compound (A) containing any of repeating units of general formula (I) below, and that the developer comprises tetrapropylammonium hydroxide.

Description

D E S C R I P T I O N
METHOD OF FORMING PATTERN,
PHOTOMASK AND NANOIMPRINT MOLD MASTER
Cross-Reference to Related Applications This application is based upon and claims the benefit of priority from prior Japanese Patent
Application No. 2012-075089, filed March 28, 2012, the entire contents of which are incorporated herein by reference.
Technical Field
The present invention relates to a method of forming a pattern in which a highly defined pattern can be formed through exposure to electron beams (EB) , extreme ultraviolet (EUV) or the like, which method can find appropriate application in an
ultramicrolithography process applicable to the
manufacturing of a super-LSI or a high-capacity
microchip, etc. and other fabrication processes.
Further, the present invention relates to a method of forming a pattern that can find appropriate application in processes for manufacturing a photomask and a nanoimprint mold master.
Background Art
Microfabrication by lithography using a
photoresist composition is performed in the process for manufacturing semiconductor devices, such as an IC and an LSI.
In recent years, the trend of exposure wavelength toward a short wavelength, for example, from g-rays to i-rays and further to a KrF excimer laser light is seen in accordance with the realization of high integration for integrated circuits. Further, now, the development of lithography using electron beams, X-rays or EUV light is being promoted.
Moreover, the lithography technology finds
application in, for example, the production of a mold master for use in what has been referred to as an imprint process (see, for example, patent reference 1 and non-patent reference 1) .
The imprint process refers to a technology
comprising impressing a mold master provided with an uneven pattern onto a resist applied on a work piece to thereby mechanically transform or flow the resist so that a micropattern is precisely transferred.
In the microfabrication using a resist composition, in recent years, the formation of a nanopattern of especially 30 nm or less is required in accordance with the realization of high integration for integrated circuits .
With respect to a method of forming a resist pattern, it is common practice to employ a method comprising patternwise exposing a resist film applied on a substrate to actinic rays or radiation and developing the exposed film with a 2.38% aqueous tetramethylammonium hydroxide (hereinafter referred to as TMAH) solution.
When the pattern becomes nanosized, in the
developing operation, there occurs a problem of
swelling phenomenon that the resist pattern is swollen by TMAH. The swell deteriorates the rectilinear propagation property of the resist pattern and causes the resist pattern to fall in the rinse treatment after development, thereby bringing about poor resolution.
In order to solve this problem, a method of using, as a developer, an alkali aqueous solution containing tetraethylammonium hydroxide (hereinafter referred to as TEAH) , tetrapropylammonium hydroxide (hereinafter referred to as TPAH) , tetrabutylammonium hydroxide (hereinafter referred to as TBAH) or the like each having a molecular weight larger than that of TMAH has been proposed.
For example, it has been reported that when a resist film containing a polymer in which the hydrogen atom of a carboxyl group is protected by an acid- unstable group is developed with an aqueous solution of TBAH, the swell of resist pattern can be inhibited in the stage of development to thereby enhance the
resolution performance (see, for example, patent references 2 to 4 and non-patent reference 2). [Citation List]
[Patent Literature]
[Patent reference 1] Jpn. Pat. Appln. KOKAI
Publication No. (hereinafter referred to as JP-A-)
2008-162101,
[Patent reference 2] Japanese Patent No. 3429592, [Patent reference 3] JP-A-2010-237661, and
[Patent reference 4] JP-A-2011-145561.
[NON-PATENT LITERATURE]
[Non-patent reference 1] "Fundamentals of
nanoimprint and its technology development/application deployment - technology of nanoimprint substrate and its latest technology deployment" edited by Yoshihiko Hirai, published by Frontier Publishing (issued in June, 2006), and
[Non-patent reference 2] Proceedings of the 70th Scientific Lecture Meeting of Japan Society of Applied Physics, No.2, p635, "Study of novel developer for EUV resist, advanced semiconductor technologies," Julius Joseph Santillan and Toshio Itani.
Disclosure of Invention
Meanwhile, in the forming of a microsized pattern through exposure to electron beams or EUV light, it is preferred to employ a resist composition comprising a polymeric compound containing hydroxystyrene as a repeating unit from the viewpoint of acid generating efficiency and dry etching resistance. As an example of such a polymeric compound, there can be mentioned a polymeric compound obtained by partially protecting the hydrogen atoms of a p-hydroxystyrene polymer in which no acrylic unit is introduced with an acetal protective group .
The hydroxyl group of a hydroxystyrene exhibits acidity weaker than the above-mentioned carboxyl group (carboxylic acid) , so that the solubility thereof in an alkali developer is lower than that of the carboxyl group. Therefore, when the development is performed with, for example, an aqueous solution of TBAH, the developer solubility tends to be poor, and some residue is likely to remain after the development, thereby causing a problem of defect.
When use is made of a developer in which the concentration of TBAH is high in order to increase the developer solubility, the TBAH contained in the
developer may precipitate to thereby cause other problems, such as occurrence of development defect.
When use is made of an aqueous solution of TEAH exhibiting a dissolution capability higher than that of the aqueous solution of TBAH, the swell of resist pattern in the stage of development cannot be
satisfactorily inhibited, thereby failing to enhance the resolution performance.
The present invention has been made in view of the foregoing problems. It is an object of the present invention to provide a method of forming a pattern in which a micropattern satisfying all of the realization of high resolution by the inhibition of pattern swell, inhibition of development defect and dry etching resistance can be formed. It is other objects of the' present invention to provide a photomask and a
nanoimprint mold master both produced by a process comprising this pattern forming method.
Extensive and intensive investigations have been conducted in view of the foregoing problems. As a result, it has been found that the above objects can be attained. by developing an actinic-ray- or radiation- sensitive resin composition comprising a polymeric compound with a specified structure with an alkali aqueous solution containing TPAH. Based on this finding, the present invention has been completed.
The present invention according to an aspect thereof is as follows.
[1] A method of forming a pattern, including forming a film of an actinic-ray- or radiation- sensitive resin composition on a substrate, exposing the film to actinic rays or radiation and developing the exposed film with a developer to thereby obtain a fine pattern, characterized in that the actinic-ray- or radiation-sensitive resin composition comprises a polymeric compound (A) containing any of repeating units of general formula (I) below, and that the developer comprises tetrapropylammonium hydroxide,
Figure imgf000008_0001
in which
each of Rn]_, RO2 and Ro3 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, provided, that RQ3 may be bonded to Ar]_ to thereby form a ring, which RQ3 represents an alkylene group,
Ar_ represents a (n+l)-valent aromatic ring group, provided that Ar^, when bonded to RQ3 to thereby form a ring, represents a (n+2)-valent aromatic ring group, n is an integer of 1 to 4, and
Y, when n≥2 each independently, represents a hydrogen atom or a group leaving when acted on by an acid, provided that at least one of Y' s is a group leaving when acted on by an acid, which group is any of groups of general formula (II) below,
C-O-M-Q (I I) in which
each of L]_ and L2 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, M represents a single bond or a bivalent
connecting group, and
Q represents an alkyl group, a cycloalkyl group, an alicyclic group, an aromatic ring group, an amino group, an ammonium group, a mercapto group, a cyano group or an acyl group, provided that each of the alicyclic group and aromatic ring group may contain a heteroatom,
provided that L]_ may be bonded to M and/or Q to thereby form a ring.
[2] The method according to item [1],
characterized in that the obtained pattern is positive, and that the developer is an alkali developer.
[3] The method according to item [2],
characterized in that the alkali developer comprises alkali components, 70 mol% or more of which are
comprised of tetrapropylammonium hydroxide.
[4] The method according to any of items [1] to [3] , characterized by further including baking
performed between the exposure and the development.
[5] The method according to any of items [1] to [4], characterized in that the exposure is performed to electron beams or EUV light.
[6] The method according to any of items [1] to [5] , characterized in that the repeating units of general formula (I) are repeating units of general formula (III) below,
Figure imgf000010_0001
in which
R21 represents a hydrogen atom or a methyl group,
AR21 represents a bivalent aromatic ring group, each of RH, and R!3 independently represents an organic group with a carbon atom as an atom bonded to C in - (CR1:LR12R13) , provided that at. least two of R11, R!2 and R^3 may be bonded to each other to thereby form a ring,
M-Ll represents a single bond or a bivalent connecting group, and
Q11 represents an' alky1 group, a cycloalkyl group or an aromatic ring group.
[7] The method according to any of items [1] to
[6] , characterized in that the actinic-ray- or
radiation-sensitive resin composition further comprises a compound (B) that when exposed to actinic rays or radiation, generates an acid and a basic compound (C) .
[8] A photomask produced by a process comprising forming a pattern on a substrate in accordance with the method according to any of items [1] to [7] and etching a surface of the substrate by use of the pattern.
[9] A nanoimprint mold master produced by a process comprising forming a pattern on a substrate in accordance with the method according to any of
items [1] to [7] and etching a surface of the substrate by use of the pattern.
The present invention has made it feasible to provide a method of forming a pattern in which a micropattern satisfying all of the realization of high resolution by the inhibition of pattern swell,
inhibition of development defect and dry etching resistance can be formed. This pattern forming method can find appropriate application in processes for producing a photomask and a nanoimprint mold master.
Brief Description of Drawings
The single figure shows a ^H-NMR chart of compound (polymer-2) synthesized in Example.
Best Mode for Carrying Out the Invention
The present invention will be described in detail below .
Herein, the term "actinic rays" or "radiation" means, for example, brightline spectra from a mercury lamp, far ultraviolet represented by an excimer laser, extreme ultraviolet (EUV light) , X-rays, electron beams (EB) or the like. The term "light" means actinic rays or radiation. The term "exposure to light" unless otherwise specified means not only irradiation with light, such as light from a mercury lamp, far
ultraviolet, X-rays or EUV light, but also lithography using particle beams, such as electron beams and ion beams .
In this description, the groups (atomic groups) for which no statement is made as to substitution or nonsubstitution are to be interpreted as including those containing no substituents and also those
containing substituents. For example, the "alkyl groups" for which no statement is made as to
substitution or nonsubstitution are to be interpreted as including not only the alkyl groups containing no substituents (unsubstituted alkyl groups) but also the alkyl groups containing substituents (substituted alkyl groups ) .
The method of forming a pattern according to the present invention and the processes for producing a photomask and a nanoimprint mold master in which the method is used will be described in detail below.
<1> Formation of film
A film of actinic-ray- or radiation-sensitive resist composition (hereinafter briefly referred to as a resist film) is obtained by dissolving individual components to be described hereinafter in a solvent, filtering the solution according to necessity and applying the same onto a support (substrate) . The filter medium for the filtration is preferably
comprised of a polytetrafluoroethylene , polyethylene or nylon having a pore size of 0.1 im or less, more preferably 0.05 μιη or less and further more preferably 0.03 μπι or less .
For the resolution of a 30 nm or less nanosized pattern, it is preferred for the thickness of the resist film to be 40 nm or less. When- the film thickness exceeds 40 nm, pattern fall prominently occurs with the result that satisfactory resolving performance cannot be attained.
More preferably, the film thickness is in the range of 15 to 40 nm. When the film thickness is less than 15 nm, it is difficult to attain satisfactory etching resistance.
Most preferably, the film thickness is in the range of 20 to 35 nm. When the film thickness falls within this range, etching resistance and resolving performance can be simultaneously satisfied.
The composition is applied onto a substrate, such as one for use in the production of integrated circuit elements (e.g., silicon, silicon dioxide coating) , by appropriate application means, such as a spinner, and thereafter dried to thereby obtain a resist film.
According to necessity, various subcoating films
(inorganic, organic films) can be provided as
underlayers of the resist film.
A heat drying method is generally employed for drying the resist film after coating application. The heating can be performed by means provided in the common exposure/development equipment. The heating can also be performed using a hot plate or the like.
The heat drying is preferably performed at a temperature at which any solvent remaining in the resist film can be satisfactorily reduced. When the amount of solvent remaining in the resist film is satisfactorily reduced, in the stage of development to be described hereinafter, the penetration of a
developer into the pattern is hindered with the result that any swell of pattern can be effectively inhibited
It is not necessarily appropriate to suggest preferred heat drying temperatures as the temperatures relate to the volatility of resist solvent employed. However, when a resist solvent is used alone, heat drying can be performed at a temperature equal to "boiling point of resist solvent - 10°C" or higher. When the employed resist solvent is comprised of a mixture of two or more solvents, heat drying can be performed at a temperature equal to " (boiling point of solvent exhibiting the highest boiling point among the resist solvents) - 10°C" or higher. At these heat drying temperatures, the amount of solvents remaining in the resist film can be satisfactorily reduced, thereby inhibiting the swell of pattern caused by the solvents remaining in the resist film. For example, when ethyl lactate (boiling point 154°C) is contained as a resist solvent and the boiling point thereof is the highest among those of contained solvents,, it. is preferred for the heat drying temperature to be 144°C (=154°C-10°C) or higher.
The period of time in which heat drying is performed is preferably in the range of 30 to
1000 seconds, more preferably 60 to 800 seconds and further more preferably 60 to 600 seconds.
<2> Exposure
The thus formed film is exposed through a given mask to actinic rays or radiation. In the exposure using electron beams, lithography through no mask
(direct lithography) is generally carried out.
The actinic rays or radiation is not particularly limited. Examples thereof include a KrF excimer laser, an ArF excimer laser, EUV light and electron beams. EUV light and electron beams are preferred.
<3> Bake
It is preferred to perform baking (heating) after the exposure but before development.
The heating temperature is preferably in the range of 80 to 150°C, more preferably 80 to 140°C and further more preferably 80 to 130°C.
The heating time is preferably in the range of 30 to 1000 seconds, more preferably 60 to 800 seconds and further more preferably 60 to 600 seconds.
The heating can be carried out by means provided in a conventional exposure/development apparatus and may also be carried out using a hot plate or the like. The bake accelerates the reaction in exposed areas, thereby enhancing the sensitivity and pattern profile.
<4> Development
In a developer, TPAH is contained as an alkali species .
It is preferred for the developer to exhibit alkalinity. Preferably, 70 mol% or more of the alkali species contained in an alkali aqueous solution are TPAH. An alkali aqueous solution containing only TPAH as the alkali species is most preferred.
It is preferred for the concentration of TPAH in a developer to be in the range of 1.5 to 4 mass%. When the concentration is lower than 1.5 mass%, a prolonged period of time is required for completing the
development, resulting in a prominent drop of
productivity. On the other hand, when the
concentration exceeds 4 mass%, film thinning is likely to occur in unexposed areas of the resist film,
resulting in deterioration of resolving performance.
The concentration of TPAH in a developer is more preferably in the range of 2.0 to 3.5 mass%. When a developer in which the TPAH concentration is in this range is used, productivity and resolving performance can be simultaneously satisfied.
A surfactant may be contained in the developer. However, a developer in which no surfactant is
contained is preferred. When the developer contains no surfactant, the wetting of the resist film and the penetration of the developer into the interior of the pattern can be appropriately retained to thereby permit controlling of the pattern swell.
As the development method, use can be made of, for example, any of a method in which the substrate is dipped in a tank filled with a developer for a given period of time (dip method) , a method in which a developer is mounded on the surface of the substrate by its surface tension and allowed to stand still for a given period of time to thereby effect development (puddle method) , a method in which a developer is sprayed onto the surface of the substrate (shower method) , a method in which a developer is continuously applied onto the substrate being rotated at a given speed while scanning a developer application nozzle at a given speed (dynamic dispense method), and the like.
As especially preferred development methods, there can be mentioned a method in which a fresh developer is continuously sprayed over a substrate surface (shower method) , a method in which a fresh developer is
continuously applied onto the substrate being rotated at a given speed while scanning a developer application nozzle at a given speed (dynamic dispense method) and a method in which a fresh developer is fed in several divisions onto a substrate to thereby effect
development . The development in exposed areas promptly
progresses when the development is performed by
continuously feeding a fresh developer onto the
substrate, thereby enhancing the resolving performance. Further, development defects attributed to any residue can be reduced.
With respect to the development time, it is important for the same to be one in which the resist film in exposed areas is satisfactorily dissolved. In particular, the development time is preferably in the range of 30 to 300 seconds, more preferably 30 to
150 seconds and most preferably 30 to 100 seconds.
When the development time is shorter than the above range, an in-plane pattern size scattering is likely to occur. When the development time is longer than the above range, a developer penetration into the pattern interior is likely to occur, resulting in pattern swelling.
The temperature of the developer is preferably in the range of 0 to 50°C, more preferably 10 to 30°C.
<Rinse treatment>
The developing operation is preferably followed by an operation of replacement with pure water intended to discontinue the development.
Before the use of the pure water, appropriate amounts of an alcohol, such as isopropyl alcohol, and a surfactant, such as a nonionic surfactant, can be added thereto.
The period of time in which this rinse s
performed is preferably one enough to satisfactorily wash away any alkali developer from the substrate. In general, the time is preferably in the range of 5 to 600 seconds, more preferably 10 to 300 seconds.
The temperature of a rinse liquid is preferably in the range of 0 to'50°C, more preferably 10 to 30°C.
<6> Process for producing patterned substrate
Now, the process for producing the patterned substrates (for example, photomask and nanoimprint mold master) of the present invention will be described. In this embodiment, the production of the patterned substrates is carried out by use of the foregoing resist pattern forming method.
First, a resist film provided with a given uneven pattern is formed on a substrate by use of the
foregoing pattern forming method. Subsequently, the substrate is etched through the patterned resist film as a mask, so that an uneven pattern corresponding to the uneven pattern of the resist film is formed on the substrate. Thus, a patterned substrate provided on its surface with a given uneven pattern is obtained.
When the substrate has a laminate structure and comprises a mask layer at its surface, a resist film provided with a given uneven pattern is formed on the substrate with the mask layer by use of the foregoing resist pattern forming method. Subsequently, dry etching is performed through the resist film as a mask, so that an uneven pattern corresponding to the uneven pattern of the resist film is formed in the mask layer. Further dry etching is performed on the substrate through the mask layer as an etch stop layer, thereby forming the uneven pattern on the substrate. Thus, a patterned substrate provided on its surface with a given uneven pattern is obtained.
Dry etching is not particularly limited as long as an uneven pattern can be formed on the substrate. An appropriate dry etching can be selected in accordance with an intended object. For example, there can be mentioned a reactive ion etching (RIE) , an ion milling method, a sputter etching and the like. Of these, a reactive ion etching (RIE) and an ion milling method are especially preferred.
Fluorine-based gases and chlorine-based gases can be used as RIE etchants.
As a material for fabricating the substrate, there can be mentioned a metallic material, such as silicon, nickel, aluminum, chromium, iron, tantalum or tungsten, or an oxide, nitride or carbide thereof. In particular, as a material for support member, there can be
mentioned silicon oxide, aluminum oxide, quartz glass, Pyrex (registered trademark) glass, soda glass or the like . The shape of the uneven pattern is not
particularly limited. The shape is appropriately selected in accordance with the application of the patterned substrate, such as a photomask or a
nanoimprint mold master. For example, there can be mentioned a line and space pattern, or a dot pattern or hole pattern with a cross section, such as a
rectangular-, circular or elliptic one.
The actinic-ray- or radiation-sensitive resin composition (hereinafter referred to as, for example, the composition according to the present invention) for use in the pattern forming method of the present invention will be described in detail below.
<1> (A) Polymeric compound
The actinic-ray- or radiation-sensitive resin composition according to the present invention
comprises a polymeric compound (A) containing any of repeating units of general formula (I) below.
The polymeric compound (A) containing any of repeating units of general formula (I) can be
synthesized from a monodisperse polymer synthesized by an anionic polymerization, etc. as a precursor, as will be described hereinafter. In the formation of a nanopattern as described in the present invention, the use of a monodisperse polymer uniformizes dissolution units in the stage of development, thereby facilitating the retention of resolution, especially low line edge roughness ( LER ) .
Figure imgf000022_0001
In general formula ( I ) , each of Roi ^02 anc^ ^03 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group. RQ3 may be bonded to Ar]_ to thereby form a ring, which RQ3 represents an alkylene group.
Ar_ represents a (n+l)-valent aromatic ring group, provided that Ar^, when bonded to RQ3 to thereby form a ring, represents a (n+2)-valent aromatic ring group.
Y, when n≥2 each independently, represents a hydrogen atom or a group leaving when acted on by an acid, provided that at least one of Y' s is a group leaving when acted on by an acid, which group is any of groups of general formula (II) below; and
n is an integer of 1 to 4, preferably 1 or 2, and more preferably 1.
Li C O— M Q (")
In general formula (II), each of L]_ and L2 · independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group.
M represents a single bond or a bivalent
connecting group.
Q represents an alkyl group, a cycloalkyl group, an alicyclic group, an aromatic ring group, an amino group, an ammonium group, a mercapto group, a cyano group or an acyl group, provided that each of the alicyclic group and aromatic ring group may contain a ' heteroatom.
L]_ may be bonded to M and/or Q to thereby form a ring .
General formulae (I) and (II) will be described in detail below.
The alkyl groups represented by RQ I to RQ 3 are, for example, alkyl groups each having up to 2 0 carbon atoms. Preferred examples. thereof are a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2 - ethylhexyl group, an octyl group and a dodecyl group.
Alkyl groups each having up to 8 carbon atoms are more preferred. Substituents may be introduced in these alkyl groups.
The alkyl group contained in the alkoxycarbonyl group is preferably any of those set forth above in connection with R Q I to Ro3-
The cycloalkyl group may be monocyclic or polycyclic. As preferred examples thereof, there can be mentioned monocycloalkyl groups each having 3 to 8 carbon atoms, such as a cyclopropyl group, a
cyclopentyl group and a cyclohexyl group. Substituents may be introduced in these cycloalkyl groups.
As the halogen atom, there can be mentioned a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. A fluorine atom is preferred.
When RQ3 is an alkylene group, the alkylene group is preferably one having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group or an octylene group
Preferably, each of RQ\, ^02 anc* ^03 independently is a hydrogen atom or an alkyl group. A hydrogen atom is more preferred.
The (ri+1) -valent aromatic ring group represented by A∑i preferably has 6 to 14 carbon atoms. As a bivalent aromatic ring group in which n is 1, there can be mentioned, for example, a phenylene group, a
tolylene group or a naphthylene group.
As preferred particular examples of the (n+1)- valent aromatic ring groups in which n is an integer of over 2, there can be mentioned groups resulting from the removal of (n-1) arbitrary hydrogen atoms from each of the above-mentioned particular examples of bivalent aromatic ring groups.
Further substituents may be introduced in these aromatic ring groups.
The alkyl groups represented by L]_ and L2 are, for example, alkyl groups each having 1 to 8 carbon atoms. As particular examples thereof, there can be mentioned a methyl group, an ethyl group, a propyl group, an n- butyl group, a sec-butyl group, a hexyl group and an octyl group.
The cycloalkyl groups represented by and L2 are, for example, cycloalkyl groups each having 3 to
15 carbon atoms. As particular examples thereof, there can be mentioned a cyclopentyl group, a cyclohexyl group, a norbornyl group and an adamantyl group.
The aryl groups represented by L]_ and L2 are, for example, aryl groups each having 6 to 15 carbon atoms. As particular examples thereof, there can be mentioned a phenyl group, a tolyl group, a naphthyl group and an anthryl group.
The aralkyl groups represented by L]_ and L2 are, for example, aralkyl groups each having 6 to 20 carbon atoms. As particular examples thereof, there can be mentioned a benzyl group and a phenethyl group.
Preferably, each of L_ and L2 independently is a hydrogen atom or an alkyl group. More preferably, one of L_ and L2 is a hydrogen atom, and the other is an alkyl group.
The bivalent connecting group represented by M is, for example, an alkylene group (preferably an alkylene group having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group or an octylene group) , a cycloalkylene group (preferably a cycloalkylene group having 3 to 15 carbon atoms, such as a cyclopentylene group or a cyclohexylene group) , an alkenylene group (preferably an alkenylene group having 2 to 8 carbon atoms, such as an ethylene group, a propenylene group or a butenylene group) , an arylene group (preferably an arylene group having 6 to 2 0 carbon atoms, such as a phenylene group, a.tolylene group or a naphthylene group), -S-, -0-, -CO-, -SO2-, -N ( RQ ) - or a combination of two or more of these groups. RQ represents a hydrogen atom or an alkyl group. The alkyl group represented by RQ is, for example, one having 1 to 8 carbon atoms. As particular examples thereof, there can be mentioned a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a hexyl group and an octyl group.
Preferably, M is a single bond, an alkylene group, -0- or a bivalent connecting group comprised of a combination of these groups. More preferably, M is a single bond, an alkylene group or an alkyleneoxy group.
The alkyl group and cycloalkyl group represented by Q are the same as those set forth above in
connection with L_ and L2.
As the alicyclic group and aromatic ring group represented by Q, there can be mentioned, for example, the cycloalkyl group and aryl group set forth above as being represented by L]_ and L2. Each of the cycloalkyl group and aryl group preferably has 3 to 15 carbon atoms .
As the heteroatom-containing alicyclic group and aromatic ring group represented by Q, there can be mentioned, for example, groups with a heterocyclic structure, such as thiirane, cyclothiorane, thiophene, furan, pyrrole, benzothiophene, benzofuran,
benzopyrrole, triazine, imidazole, benzimidazole, triazole, thiadiazole, thiazole and pyrrolidone.
However, the heteroatom-containing alicyclic group and aromatic ring group are not limited to these as long as the ring is formed of carbon and a heteroatom, or of heteroatoms only.
As the acyl group represented by Q, there can be mentioned a formyl group, an acetyl group, a propanoyl group, a benzoyl group or the like.
Preferably, Q is an alkyl group, · a cycloalkyl group, an alicyclic group or an aromatic ring group. More preferably, Q is an alkyl group, a cycloalkyl group or an aromatic ring group.
As the ring structure that may be formed by the mutual bonding of L]_ and M and/or Q, there can be mentioned, for example, a 5-membered or 6-membered ring structure formed through the formation of a propylene group or a butylene group thereby. The 5-membered or 6-membered ring structure contains the oxygen atom appearing in general formula (II) .
Substituents may be introduced in the groups represented by L]_, L2, M and Q in general formula (II) . As the substituents, there can be mentioned, for example, an alkyl group, a cycloalkyl group, an aryl group, an amino group, an amido group, a ureido group, a urethane group, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group, a thioether group, an acyl group, an acyloxy group, an alkoxycarbonyl group, a cyano group and a nitro group. Preferably, the number of carbon atoms of each of these substituents is up to 8.
The groups of the formula - (M-Q) are preferably groups each having 1 to 30 carbon atoms, more
preferably 5 to 20 carbon atoms. In particular, from the viewpoint of suppression of outgassing, it is preferred for each of the groups to have 6 or more carbon atoms .
It is preferred for the repeating units of general formula (I) to be those of general formula (III) below.
Figure imgf000028_0001
In the formula, R21 represents a hydrogen atom or a methyl group.
Ar^l represents a bivalent aromatic ring group.
Each of Rll, R1 2 and Rl3 independently represents an organic group with a carbon atom as an atom bonded to C in - ( CR1 :L R1 2 R1 3 ) , provided that at least two of RI I , R12 anc[ R13 may be bonded to each other to thereby form a ring.
Mll represents a single bond or a bivalent connecting group.
Q11 represents an alkyl group, a cycloalkyl group or an aromatic ring group.
Particular examples of the bivalent aromatic ring groups represented by Ar2^ are the same as set forth above in connection with Ar^ in general formula (I) .
M^-l is the same as M in general formula .(I) .
The alkyl group, cycloalkyl group and aromatic ring group represented by are the same 'as set forth above in connection, with Q in general formula ( I ) .
As mentioned above, each of R R^ 2 and R13 independently represents an organic group.
Herein, the term "organic group" means a group containing at least one carbon atom. One of the contained carbon atoms is bonded to C in the
group - ( CR1 1 R1 2 R1 3 ) .
Each of the organic groups represented by R^- , R^ 2 and R!3 j_s preferably an organic group containing a carbon-hydrogen bond moiety. When two or more carbon atoms, are contained, the organic group may be a
saturated organic group wherein any carbon-carbon bond is comprised of a single bond only, or may be an
unsaturated organic group wherein the carbon-carbon bonds contain a moiety comprised of a double bond or triple bond. Further, each of the organic groups may contain a heteroatom, such as an oxygen atom, a
nitrogen atom or a sulfur atom.
Each of RH , ' and R!3 can be, for example, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or a heterocyclic group comprising carbon atom linkage. The heterocyclic group comprising carbon atom linkage may be aromatic or nonaromatic.
The alkyl group in its one form preferably
contains 20 or less carbon atoms, more preferably 8 or less carbon atoms. The alkyl group can be, for example, any of a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group and a dodecyl group. Of these, a methyl group, an ethyl group, a propyl group, an isopropyl group and a t-butyl group are especially preferred.
The cycloalkyl group may be monocyclic or
polycyclic. The cycloalkyl group preferably contains 3 to 10 carbon atoms. The cycloalkyl group can be, for example, any of a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a 1-adamantyl group, a 2- adamantyl group, a 1-norbornyl group and a 2-norbornyl group. Of these, a cyclopentyl group and a cyclohexyl group are preferred.
The aryl groups include a structure (for example, a biphenyl group or a terphenyl group) in which a plurality of aromatic rings are linked to each other through a single bond. Each of the aryl group
preferably has 4 to 20 carbon atoms, more preferably 6 to 14 carbon atoms. The aryl groups can be, for example, a phenyl group, a naphthyl group, an anthranyl group, a biphenyl group, a terphenyl group and the like Of these, a phenyl group, a naphthyl group and a biphenyl group are especially preferred.
The aralkyl group preferably has 6 to 20 carbon atoms, more preferably 7 to 12 carbon atoms. The aralkyl group can be, for example, any of a benzyl group, a phenethyl group, a naphthylmethyl group and a naphthylethyl group.
A substituent may further be introduced in each of the alkyl group, cycloalkyl group, aryl group and aralkyl group.
As the substituent that may further be introduced in the alkyl group, there can be mentioned, for example a cycloalkyl group, an aryl group, an amino group, an amido group, a ureido group, a urethane group, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group, an aralkyloxy group, a thioether group, an acyl group, an acyloxy group, an alkoxycarbonyl group, a cyano group or a nitro group.
As the substituent that may further be introduced in the cycloalkyl group, there can be mentioned an alkyl group or any of the groups mentioned above as examples of the substituents that may further be introduced in the alkyl group.
The substituent that may further be introduced in the alkyl group or cycloalkyl group preferably has 8 or less carbon atoms.
As the substituent that may further be introduced in the aryl group or aralkyl group, there can be mentioned, for example, a nitro group, a halogen atom such as a fluorine atom, a carboxyl group, a hydroxyl group, an amino group, a cyano group, an alkyl group (preferably having 1 to 15 carbon atoms) , an alkoxy group (preferably having 1 to 15 carbon atoms), a cycloalkyl group (preferably having 3 to 15 carbon atoms), an aryl group (preferably having 6 to 14 carbon atoms) , an alkoxycarbonyl group (preferably having 2 to 7 carbon atoms) , an acyl group (preferably having 2 to 12 carbon atoms) or an alkoxycarbonyloxy group
(preferably having 2 to 7 carbon atoms).
With respect to the heterocyclic group comprising carbon atom linkage, the expression "carbon atom linkage" means that the atom bonded to C in - (CR11R1 2 R13) j_s a carbon atom. The■ heterocycle may be an aromatic ring or a nonaromatic ring, and
preferably contains 2 to 20 carbon atoms, more
preferably 4 to 14 carbon atoms. As the heterocyclic group comprising carbon atom linkage, there can be mentioned a pyrrolyl group, a pyridyl group, a
pyrimidyl group, a furanyl group, a thienyl group, a tetrahydrofuranyl group, a tetrahydropyranyl group, a tetrahydrothienyl group, a pyrrolidinyl group, a morpholinyl or the like.
At least two of R1 1 , R1 2 and R1 3 may be bonded to each other to thereby form a ring. When two of R^ , and R13 are bonded to each other to thereby form a ring, the formed ring can be, for example, any of a cyclopentane ring, a cyclohexane ring, an adamantane ring, a norbornene ring and a norbornane ring. A substituent may be introduced in each of these. As the introducible substituent, there can be mentioned an alkyl group or any of the groups mentioned above as examples of the substituents that may further be introduced in the alkyl group. When all of RH , R^ 2 and R13 are bonded to each other to thereby form a ring the formed ring can be, for example, any of an
adamantane ring, a norbornane ring, a norbornene ring, a bicyclo [2, 2, 2] octane ring and a bicyclo [ 3 , 1 , 1 ] heptane ring. Of these, an adamantane ring is most preferred. A substituent may be introduced in each of these. As the introducible substituent, there can be mentioned an alkyl group or any of the groups mentioned above as examples of the substituents that may further be introduced in the alkyl group.
From the viewpoint of dry etching resistance and increase of the glass transition temperature of polymeric compound (A) , it is preferred for at least one of RH, R12 and R13 to have a cyclic structure. More preferably, at least two of Rll, R!2 and R13 are bonded to each other to thereby form a ring. Most preferably, all of Rll, Rl2 and Rl3 are bonded to each other to thereby form a ring.
Particular examples of the moieties of general formula ( I I ) and the moieties of the formula
[ -CH ( CRN R1 2R1 3 ) -0-M1 -Q H] in general formula ( I I I ) are shown below.
Figure imgf000034_0001
Figure imgf000035_0001
tBu Me
Figure imgf000036_0001
The content of repeating unit of general formula above in the polymeric compound (A) according to the present invention, based on all the repeating units of the polymeric compound (A), is preferably _in the range of 5 to 50 mol%, more preferably 10 to 40 mol% and most preferably 15 to 40 mol%.
When the composition of the present invention is to be exposed to a KrF excimer laser light, electron beams, X-rays or high-energy light rays of wavelength 50 nm or less (for example, EUV) , it is preferred for the polymeric compound (A) to further contain a hydroxystyrene repeating unit.
When the polymeric compound (A) contains a hydroxystyrene repeating unit, the content of
hydroxystyrene repeating unit based on all the repeating units of the polymeric compound (A) is preferably in the range of 3 to 90 mol%, more
preferably 5 to 90 mol% and most preferably 7 to 85 mol%.
Particular examples of the hydroxystyrene units are shown below.
Figure imgf000037_0001
The polymeric compound (A) may further contain repeating units other than the foregoing repeating units. As such other repeating units, there can be mentioned a repeating unit being stable against the action of an acid to be described below.
As the repeating unit being stable against the action of an acid, there can be mentioned, for example, a styrene derivative with a non-acid-decomposable substituent, such as any of those of general formula (IV) below, or a repeating unit in which a side chain of acrylic structure has a non-acid-decomposable aryl structure, cycloalkyl structure or lactone structure, such as any of those of general formula (V) below. The regulation of contrast, enhancement of etching
resistance, etc. can be expected by the introduction of this structure.
Figure imgf000038_0001
In general formula (IV),
Ra represents a hydrogen atom, an alkyl group or a group of the formula -CH2-0-Ra2 in which Ra2 represents a hydrogen atom, an alkyl group or an acyl group. Each of the alkyl groups represented by Ra and Ra2
preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms . A substituent may further be
introduced in each of the alkyl groups represented by Ra and Ra2 · As the substituent, there can be mentioned, for example, a halogen atom, such as a fluorine atom or a chlorine atom. The alkyl group represented by Ra is, for example, a methyl group, a chloromethyl group, a trifluoromethyl group or the like.
Ra is preferably a hydrogen atom, a methyl group, a hydroxymethyl group or a trifluoromethyl group, most preferably a hydrogen atom or a methyl group.
In general formula (IV) , B represents an acyl group, an alkyl group, a cycloalkyl group, an alkoxy group, an acyloxy group or an alkoxycarbonyl group. B is preferably an acyloxy group or an alkoxycarbonyl group, more preferably an acyloxy group. Among acyloxy groups (general formula -O-CO-R^ in which R^ is an alkyl group), those in which R^ has 1 to 6 carbon atoms are preferred, and those in which R^ has 1 to 3 carbon atoms are more preferred. more preferably 1 to 3 carbon atoms. The acyloxy group in which R^ has one carbon atom (namely, acetoxy group) is most preferred.
In the formula, p is an integer of 0 to 5,
preferably 0 to 2, more preferably 1 or 2 and further more preferably 1.
Substituents may be introduced in these groups represented by B. As preferred substituents, there can be mentioned a hydroxyl group, a carboxyl group, a cyano group, a halogen group (a fluorine atom, a chlorine atom, a bromine- atom or an iodine atom) , an alkoxy group (a methoxy group, an ethoxy group, a propoxy group, a butoxy group or the like) and the like. With respect to cyclic structures, as substituents , there can further be mentioned an alkyl group
(preferably having 1 to 8 carbon atoms) .
In general formula (V) , R5 represents a non-acid- decomposable hydrocarbon group.
Ra represents a hydrogen atom, an alkyl group or a group of the formula -CH2-0-Ra2- In this formula, Ra2 represents a hydrogen atom, an alkyl group or an acyl group. Each of the alkyl groups represented by Ra and Ra2 preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. A substituent may further be introduced in each of the alkyl groups represented by Ra and Ra2. As the substituent, there can be mentioned, for example, a halogen atom, such as a fluorine atom or a chlorine atom. The alkyl group represented by Ra is, for example, a methyl group, a chloromethyl group, a trifluoromethyl group or the like.
Ra is preferably a hydrogen atom, a methyl group, a hydroxymethyl group or a trifluoromethyl group, most preferably a hydrogen atom or a methyl group.
It is preferred for R5 to be a hydrocarbon group with a ring structure. As particular' examples of the hydrocarbon groups each with a ring structure, there can be mentioned a mono- or polycycloalkyl group
(preferably 3 to 12 carbon atoms, more preferably 3 to 7 carbon atoms), a mono- or polycycloalkenyl group (preferably 3 to 12 carbon atoms) , an aryl group
(preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms) , an aralkyl group (preferably 7 to 20 carbon atoms, more preferably 7 to 12 carbon atoms) and the like.
A substituent may further be introduced in each of these groups represented by R5. As the substituent, there can be mentioned, for example, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a halogen atom or the like.
It is optional for the polymeric compound (A) according to the present invention to contain repeating units of general formulae (IV) and (V). When the repeating units are contained, the content thereof based on all the repeating units of the polymeric compound (A) is preferably in the range of 1 to 40 mol% more preferably 2 to 20 mol%.
Particular examples of the repeating units of general formulae (IV) and (V) are shown below, which in no way limit the scope of the present invention. In the formulae, Ra represents H, CH3, CH2OH or CF3.
Figure imgf000042_0001
Figure imgf000043_0001
The polymeric compound (A) according to the present invention may be one resulting from
copolymerization with other polymerizable monomers permitting the control of film forming property and solvent solubility.
Nonlimiting examples of such other polymerizable monomers include a hydrogenated hydroxystyrene, maleic anhydride, an acrylic acid derivative (acrylic acid, an acrylic ester, etc.), a methacrylic acid derivative (methacrylic acid, a methacrylic ester, etc.), an N- substituted maleimide, acrylonitrile, methacrylonitrile and the like.
Aside from the foregoing, as preferred repeating units of the polymeric compound, there can be mentioned a unit having in its principal chain a cyclic structure (for example, a unit derived from a monomer with an indene structure) , a unit with a naphthol structure, a repeating unit containing a -C(CF3)20H group and the like.
When the polymeric compound (A) contains repeating units derived from the above polymerizable monomers or these repeating units, the content of such repeating units based on all the repeating units of the polymeric compound (A) is preferably in the range of 1 to 30 mol% more preferably 1 to 10 mol%.
In the present invention, one of the polymeric compounds (A) may be used alone, or two or more thereof may be used in combination.
The polymeric compound (A) may further comprise a repeating unit containing in its side chain a group (hereinafter also referred to as a "photoacid
generating group") that when exposed to actinic rays or radiation, generates an acid. In that instance, the compound (B) that when exposed to actinic rays or radiation, generates an acid to be described
hereinbelow is not an independent compound and is regarded as a constituent of the polymeric compound (A) according to the present invention. Namely, in an aspect of the present invention, it is preferred for the polymeric compound (A) to further comprise a repeating unit containing in its side chain a group that when exposed to actinic rays or radiation,
generates an acid, so that the polymeric compound (A) and the compound (B) to be described hereinbelow are identical compounds.
As a repeating unit containing a photoacid
generating group, there can be mentioned, for example, any of the repeating units described in section [0028] of JP-A-H9-325497 and repeating units described in sections [0038] to [0041] of JP-A-2009-93137. In that instance, it can be considered that this repeating unit containing a photoacid generating group corresponds to the compound (B) capable of generating an acid upon exposure to actinic rays or radiation according to the present invention.
It is optional for the polymeric compound (A) according to the present invention to contain the repeating unit containing a photoacid generating group in its side chain. When the repeating unit is
contained, the content of repeating unit containing a photoacid generating group in its side chain, based on all the repeating units of the polymeric compound (A) , is preferably in the range of 1 to 10 mol%, more preferably 2 to 8 mol%.
The mass average molecular weight of the polymeric compound (A) for use in the present invention is preferably ten thousand or less, more preferably in the range of 1000 to 8000 and most preferably 2000 to 6000.
When the molecular weight of the polymeric
compound is as mentioned above, satisfactory resolving performance and LER performance can be attained.
The polydispersity index (Mw/Mn) of the polymeric compound (A) is preferably in the range of 1.0 to 1.7, more preferably 1.0 to 1.2.
The mass average molecular weight (Mw) and
polydispersity index (Mw/Mn) of the polymeric compound (A) are determined by a polystyrene-equivalent GPC (gel permeation chromatography) method (solvent: THF) .
The polymeric compound (A) can be synthesized by a heretofore known radical polymerization method or anionic polymerization method. For example, in the radical polymerization method, a polymer can be
obtained by dissolving a vinyl monomer in an
appropriate organic solvent, adding a peroxide (benzoyl peroxide, etc. ) , a nitrile compound
(azobisisobutyronitrile, etc.) or a redox compound (cumene hydroperoxide - ferrous salt, etc.) as an initiator to the solution and performing a reaction at room temperature or in heated conditions. In the anionic polymerization method, a polymer can be
obtained by dissolving a vinyl monomer in an
appropriate organic solvent, adding a metal compound (butyllithium, etc.) as an initiator to the solution and performing a reaction generally in cooled
conditions.
Also, the polymeric compound (A) can be
synthesized by a method in which a polymer is
synthesized by polymerizing unsaturated monomers corresponding to precursors of individual repeating units and modified with a low-molecular compound to thereby permit conversion to desired repeating units. In both instances, it is preferred to employ living polymerization, such as living anionic polymerization, from the -viewpoint that the molecular weight- distribution of obtained polymeric compound is uniform.
Particular examples of the above-described
polymeric compounds are shown below, which in no way limit the scope of the present invention.
Figure imgf000048_0001

Figure imgf000049_0001
Figure imgf000050_0001
Figure imgf000051_0001
Figure imgf000052_0001
Figure imgf000053_0001
Figure imgf000054_0001
Figure imgf000055_0001
Figure imgf000056_0001
Figure imgf000057_0001
<2> (B) Compound that when exposed to actinic rays or radiation, generates an acid
It is preferred for the composition of the present invention to contain a compound (B) (hereinafter also referred to as an "acid generator (B) ") that when exposed to actinic rays or radiation, generates an acid It is more preferred to contain a compound that when exposed to actinic rays or radiation, generates an acid other than carboxylic acids. As such acid generators, use can be made of members appropriately selected from among a photoinitiator for photocationic polymerization a photoinitiator for photoradical polymerization, a photo-achromatic agent and photo-discoloring agent for dyes, any of heretofore known compounds that when exposed to actinic rays or radiation, generate acids, employed in microresists , etc., and mixtures thereof.
As preferred compounds that when exposed to actinic rays or radiation, are decomposed to thereby generate acids among the acid generators (B) , there can be mentioned the compounds of general formulae (ZI), (ZII) and (ZIII) below.
Figure imgf000058_0001
In the above general formula (ZI), each of R20I' R202 anci R203 independently represents an organic group Z~ represents a nonnucleophilic anion. As preferred nonnucleophilic anions, there can be
mentioned a sulfonate anion, a bis (alkylsulfonyl) amide anion, a tris (alkylsulfonyl ) methide anion, BF4-, PFg~, SbFg-, etc. Organic anions containing a carbon atom are preferred. As preferred organic anions, there can be mentioned those of formulae AN1 to AN3 below.
RC1S02 RciS02
Rc- SO^ N Rc2SO2-C
Rc2SO Rc3SO2
AN1 AN2 AN3
In formulae AN1 to AN3, each of Rc]_ to RC3
independently represents an organic group.
As the organic groups represented by Rc_ to RC3, there can be mentioned those each having 1 to 30 carbon atoms-, preferably opuicr.aiiy substituted alkyl groups, optionally substituted aryl groups and groups each resulting from the linkage of two or more thereof by means of a connecting group, such as a single bond, -0-, -CO2-, -S-, -SO3- or -SO2N (Rd]_ ) - . These organic groups may form ring structures in cooperation with other bonded alkyl groups and aryl groups.
Rd^ represents a hydrogen atom or an alkyl group, and may form a ring structure in cooperation with other bonded alkyl and aryl groups.
Each of the organic groups represented by Rc]_ to RC3 may be an alkyl group substituted at its 1-position with a fluorine atom or a fluoroalkyl group, or a phenyl group substituted with a fluorine atom or a fluoroalkyl group. The incorporation of a fluorine atom or a fluoroalkyl group increases the acidity of an acid generated upon exposure to light, thereby
realizing a sensitivity enhancement. · When five or more carbon atoms are contained in Rc]_ to RC3, it is
preferred to effect the substitution of at least one carbon atom with a hydrogen atom. It is more preferred to render the number of hydrogen atoms greater than that of fluorine atoms. The avoidance of a
perfluoroalkyl group having 5 or more carbon atoms diminishes ecological toxicity.
In general formula (ZI) above, each of the organic groups represented by R20I' R202 an<^ R203 generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
Two of R20I to R203 may ke bonded to each other to thereby form a ring structure, and the ring within the same may contain an oxygen atom, a sulfur atom, an ester bond, an amido bond or a carbonyl group.
As the group formed by the bonding of two of R201 to 203' there can be mentioned an alkylene group (for example, a butylene group or a pentylene group) .
As particular examples of the organic groups represented by R2OI' R202 anc^ R203' there can be mentioned the corresponding groups contained in the compounds (ZI-1), (ZI-2) and (ZI-3) to be described below .
Use may be made of a compound with a plurality of structures of general formula (ZI) . For example, use may be made of compounds with a structure wherein at least one of 201 to R203 °f an °f compounds of general formula (ZI) is bonded to at least one of R20I to 203 °f another of compounds of general formula (ZI)
As preferred compounds (ZI), there can be
mentioned the following compounds (ZI-1), (ZI-2) and (ZI-3) .
Compounds (ZI-1) are compounds of general formula (ZI) above wherein at least one of R20I to ^203 i- s an aryl group. Namely, compounds (ZI-1) are arylsulfonium compounds, i.e., compounds each containing an
arylsulfonium as a cation.
With respect to the arylsulfonium compounds, all of R20I to ^203 may be aryl groups. It is also
appropriate that R201 to R203 are partially an aryl group and the remainder is an alkyl group.
As the arylsulfonium compounds, there can be mentioned, for example, a triarylsulfonium compound, a diarylalkylsulfonium compound and an
aryldialkylsulfonium compound.
The aryl group contained in the arylsulfonium compounds is preferably an aryl group, such as a phenyl group or a naphthyl group, or a heteroaryl group, such as an indole residue or a pyrrole residue. A phenyl group and an indole residue are more preferred. When the arylsulfonium compound contains., two or more aryl groups, the two or more aryl groups may be identical to or different from each other.
The alkyl group . and cycloalkyl group contained in the arylsulfonium compounds according to necessity are preferably a linear or branched alkyl group having 1 to 15 carbon atoms and a cycloalkyl group having 3 to 15 carbon atoms, respectively. As such, there can be mentioned, for example, a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a cyclopropyl group, a cyclobutyl group, a cyclohexyl group and the like.
The aryl group and alkyl group represented by R20I to R203 maY contain as substituents thereof an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms), an alkoxy group (for example, 1 to 15 carbon atoms), a halogen atom, a hydroxyl group and a phenylthio group.
Preferred substituents are a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms and a linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms. An alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms are most preferred. The substituent may be introduced in any one of the three R20I to R203' or alternatively may be introduced in all of the three R20I to R203- When R201 to R203 represent aryl groups, the substituent is preferably introduced in the- p-position of the aryl group.
Now, compounds (ZI-2) will be described.
Compounds (ZI-2) are compounds of formula (ZI) wherein each of R201 to R203 independently represents an organic group containing none of aromatic rings.
The aromatic rings include ah aromatic ring containing a heteroatom.
Each of the organic groups containing no aromatic ring represented by R20I to ¾03 generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
Preferably, each of R201 to R203 independently represents an alkyl group, a cycloalkyl group, a
2-oxoalkyl group, an alkoxycarbonylmethyl group, an allyl group or a vinyl group. A linear, branched or cyclic 2-oxoalkyl group and an alkoxycarbonylmethyl group are more preferred. A linear or branched
2-oxoalkyl group is most preferred.
Each of the alkyl groups represented by R20I to R203 may be linear or branched and is preferably a linear or branched alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group) . Each of the cycloalkyl groups represented by 20I to R203 ^s for example, a cycloalkyl group having 3 to 10 carbon atoms (a cyclopentyl group, a cyclohexyl group or a norbornyl group) . Each of the 2-oxoalkyl groups represented by R201 to R203 maY be linear, branched or cyclic. A group resulting from the introduction of >C=0 in the 2- position of any of the above alkyl and cycloalkyl groups is preferred.
As preferred examples of the alkoxy groups contained in the alkoxycarbonylmethyl groups
represented by R20I to 203' there can be mentioned alkoxy groups each having 1 to 5 carbon atoms (a methoxy group, an ethoxy group, a propoxy group, a butoxy group and a pentoxy group) .
Each of R20I to R203 maY ke further substituted with a halogen atom, an alkoxy group (for example, 1 to 5 carbon atoms), a hydroxyl group, a cyano group or a nitro group.
Two of R20I to R203 may be bonded to each other to thereby form a ring structure. The ring structure within the same may contain an oxygen atom, a sulfur atom, an ester bond, an amido bond or a carbonyl group. As the group formed by the mutual bonding of two of R201 to 203' there can be mentioned an alkylene group (e.g., a butylene group or a pentylene group).
Below, compounds (ZI-3) will be described.
Compounds (ZI-3) are compounds of general formula (ZI-3) below, being compounds with a phenacylsulfonium salt structure.
Figure imgf000065_0001
Each of R]_c to R5C independently represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.
Each of Rgc and R7C represents a hydrogen atom or an alkyl group.
Each of Rx and Ry independently represents an alkyl group, a 2-oxoalkyl group, an
alkoxycarbonylmethyl group, an allyl group or a vinyl group.
Any two or more of R]_c to R7C may be bonded to each other to thereby form a ring structure. Rx and Ry may be bonded to each other to thereby form a ring structure. Each of these ring structures may contain an oxygen atom, a sulfur atom, an ester bond or an amido bond.
X- has the same meaning as that of Z~ in general formula (ZI) .
As particular examples of the compounds (ZI-3), there can be mentioned, for example, compounds shown as examples in sections 0047 and 0048 of JP-A-2004-233661 and sections 0040 to 0046 of JP-A-2003-35948.
General formulae (ZII) and (ZIII) above will be described below. In general formulae (ZII) and (ZIII), each of 204 to R207 independently represents an optionally
substituted aryl group, an optionally substituted alkyl group or an optionally substituted cycloalkyl group.
Particular examples and preferred examples of the aryl groups represented by R204 to R207 are the same as set forth above in connection with R201 to R203 in compounds (ZI-1).
Particular examples and preferred examples of the alkyl and cycloalkyl groups represented by R204 to R207 are the same as set forth above in connection with the linear or branched alkyl group and cycloalkyl group represented by 20I to R203 i-n compounds (ZI-2).
Z~ is as defined above in connection with general formula (ZI) .
As other preferred compounds among the compounds that when exposed to actinic rays or radiation,
generate acids, as acid generators (B) , there can be mentioned the compounds of general formulae (ZIV) , (ZV) and (ZVI) below.
Ar3-S02-S02-Ar4
ZIV
Figure imgf000066_0001
In general formulae (ZIV) to (ZVI),
each of Ar3 and Ar4 independently represents a substituted or unsubstituted aryl group.
Each of 208s i-n general formulae (ZV) and (ZVI) independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aryl group. Substituting 208 with a fluorine atom is preferred from the viewpoint of increasing the strength of generated acid.
Each of R209 anc ¾10 independently represents a substituted or unsubstituted alkyl group, a substituted or .unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or an electron withdrawing group. R209 is preferably a substituted or
unsubstituted aryl group. R21O i-s preferably an electron withdrawing group, more preferably a cyano group or a fluoroalkyl group.
A represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted
alkenylene group, or a substituted or unsubstituted arylene group .
Also, a compound with a plurality of structures of general formula (ZVI) is preferred in the present invention. For example, use may be made of compounds with a structure wherein either R209 or ¾10 ° an °f compounds of general formula (ZVI) is bonded to either R209 or ¾10 °f another of compounds of general formula (ZVI) .
Among the compounds that when exposed to actinic rays or radiation, are decomposed to thereby generate acids other than carboxylic acids, as acid generators (B) , the compounds of general formulae (ZI) to (ZIII) are preferred. The compounds of general formula (ZI) are more preferred, and the compounds of general formulae (ZI-1) to (ZI-3) are most preferred.
Nonlimiting particular examples of the acid generators (B) are shown below.
Figure imgf000068_0002

Figure imgf000069_0001
Figure imgf000070_0001
Figure imgf000071_0001
Any one of the foregoing acid generators (B) may be used alone, or two or more thereof may be used in combination. When two or more of the acid generators are used in combination, it is preferred to combine compounds capable of generating two types of organic acids that are different from each other by two or more in the total number of atoms excluding hydrogen atoms.
The content of acid generator (B) in the
composition, based on the total solids of the
composition of the present invention, is preferably in the range of 5 to 50 mass%. When the exposure is performed using EUV light or electron beams, it is preferred for the content to be in the range of 15 to 40 mass%, especially 20 to 35 mass%.
When the content of acid generator (B) is lower than the above ranges, the amount of acid generated upon exposure becomes extremely small to thereby deteriorate the pattern quality. On the other hand, when the content exceeds the above ranges, pattern fall is likely to occur due to, for example, a decrease of the strength of resist film and an increased
penetration of developer.
<3> (C) Basic compound
It is preferred for the composition of the present invention to contain a basic compound.
The basic compound is preferably a nitrogen- containing organic basic compound.
Useful compounds are not particularly limited. However, for example, the compounds of categories (1) to (4) below are preferably used.,
(1) Compounds of general formula (BS-1) below
R
(BS-1 )
R— N— R
In general formula (BS-1),
each of R' s independently represents any of a hydrogen atom, an alkyl group (linear or branched) , a cycloalkyl group (mono- or polycyclic) , an aryl group and an aralkyl group, provided that in no event all three R' s are hydrogen atoms.
The number of carbon atoms of the alkyl group represented by R is not particularly limited. However, it is generally in the range of 1 to 20, preferably 1 to 12.
The number of carbon atoms of the cycloalkyl group represented by R is not particularly limited. However, it is generally in the range of 3 to 20, preferably 5 to 15.
The number of carbon atoms of the aryl group represented by R is not particularly limited. However, it is generally in the range of 6 to 20, preferably 6 to 10. In particular, a phenyl group, a naphthyl group and the like can be mentioned.
The number of carbon atoms of the aralkyl group represented by R is not particularly limited. However, it is generally in the range of 7 to 20, preferably 7 to 11. In particular, a benzyl group and the like can be mentioned.
In the alkyl group, cycloalkyl group, aryl group and aralkyl group represented by R, a hydrogen atom thereof may be replaced by a substituent. As the substituent, there can be mentioned, for example, an alkyl group, a . cycloalkyl group, an aryl group, an aralkyl group, a hydroxyl group, a carboxyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an alkyloxycarbonyl group . or the like.
In the compounds of general formula (BS-1) , preferably, only one of R' s is a hydrogen atom. Also, preferably, all R' s are not hydrogen atoms.
Specific examples of the compounds of general formula (BS-1) include tri-n-butylamine , tri-n- pentylamine, tri-n-octylamine, tri-n-decylamine , triisodecylamine , dicyclohexylmethylamine,
tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, didecylamine, methyloctadecylamine, dimethylundecylamine, N, -dimethyldodecylamine, methyldioctadecylamine, N, -dibutylaniline, N,N- dihexylaniline, 2 , 6-diisopropylaniline, 2, 4, 6-tri it- butyl) aniline and the like.
Any of compounds of general formula (BS-1) in which at least one R is a hydroxylated alkyl group can be mentioned as a preferred form. As particular compounds, there can be mentioned triethanolamine, N,N dihydroxyethylaniline and the like.
With respect to the alkyl group represented by R, an oxygen atom may be introduced in the alkyl chain to thereby form an alkyleneoxy chain. The alkyleneoxy chain is preferably -CH2CH2O-. As particular examples there can be mentioned tris (methoxyethoxyethyl) amine, compounds shown by way of example in column 3 line 60 et seq. of USP 6,040,112 and the like.
(2) Compound with nitrogen-containing heterocycli structure
The heterocyclic structure may be aromatic or nonaromatic. It may contain a plurality of nitrogen atoms, and also may contain a heteroatom other than nitrogen. For example, there can be mentioned
compounds with an imidazole structure (2- phenylbenzimidazole, 2 , 4 , 5-triphenylimidazole and the like) , compounds with a piperidine structure (N- hydroxyethylpiperidine, bis (1,2, 2, 6, 6-pentamethyl-4- piperidyl) sebacate and the like) , compounds with a pyridine structure ( 4-dimethylaminopyridine and the like) and compounds with an antipyrine structure
(antipyrine, hydroxyantipyrine and the like) .
Further, compounds with two or more ring
structures can be appropriately used. In particular, there can be mentioned, for example, 1,5- diazabicyclo [ .3.0] non-5-ene and 1,8- diazabicyclo [5.4.0] -undec-7-ene .
(3) Amine compound containing phenoxy group
The amine compounds each containing a phenoxy group. are those containing a phenoxy group at the end of the alkyl group of each of the amine compounds opposite to the nitrogen atom. A substituent may be introduced in the phenoxy group. The substituent is, for example, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic ester group, a sulfonic ester group, an aryl group, an aralkyl group, an acyloxy group or an aryloxy group .
Compounds containing at least one alkyleneoxy chain between the phenoxy group and the nitrogen atom are preferred. The number of alkyleneoxy chains in each molecule is preferably in the range of 3 to 9, more preferably 4 to 6. Among the alkyleneoxy chains, -CH2CH2O- is most preferred.
Particular examples thereof include 2- [2-{2- (2, 2- dimethoxy-phenoxyethoxy) ethyl } -bis (2-methoxyethyl ) ] - amine and compounds (Cl-1) to (C3-3) shown by way of example in section [0066] of US Patent Application Publication No. 2007/0224539 Al .
(4) Ammonium salt
Ammonium salts can also be appropriately used. Ammonium hydroxides and carboxylates are preferred. Particular preferred examples thereof are
tetraalkylammonium hydroxides, such as
tetrabutylammonium hydroxide. Aside from these, use can be made of ammonium salts derived from the above amines ( 1 ) to ( 3 ) .
As other basic compounds usable in the composition of the present invention, there can be mentioned compounds synthesized in Examples of JP-A-2002-3631 6, compounds described in section [0108] of JP-A-2007- 298569 and the like.
One of these basic compounds may be used alone, or two or more thereof may be used in combination.
The amount of basic compound added is generally in the range of 0.001 to 10 mass%, preferably 0.01 to 5 mass%, based on the total solids of the composition.
The molar ratio of acid generator/basic compound is preferably in the range of 1.5 to '50. Namely, a molar ratio of 1.5 or higher is preferred from the viewpoint of the enhancement of sensitivity and
resolution. A molar ratio of 50 or below is preferred from the viewpoint of the inhibition of any resolution deterioration due to pattern thickening over time until baking treatment after exposure. The molar ratio is more preferably in the range of 2 to 30, further more preferably 3 to 20.
<4> Solvent for resist
The solvent usable in the preparation of the composition is not particularly limited as long as the individual components can be dissolved. For example, use can be made of an alkylene glycol monoalkyl ether carboxylate (propylene glycol monomethyl ether acetate (PGMEA; l-methoxy-2-acetoxypropane ) or the like), an alkylene glycol monoalkyl ether (propylene glycol monomethyl ether (PGME; l-methoxy-2-propanol ) or the like) , an alkyl lactate (ethyl lactate, methyl lactate or the like) , a cyclolactone (γ-butyrolactone or the like, preferably having 4 to 10 carbon atoms), a chain or cyclic ketone (2-heptanone, cyclohexanone or the like, preferably having 4 to 10 carbon atoms), an alkylene carbonate (ethylene carbonate, propylene carbonate or the like) , an alkyl carboxylate (preferably an alkyl acetate such as butyl acetate) , an alkyl alkoxyacetate (ethyl ethoxypropionate ) or the like. As other useful solvents, there can be mentioned, for example, those described in section [0244] et seq. of US Patent Application Publication NO. 2008/0248425 Al, and the like.
Among these solvents, an alkylene glycol monoalkyl ether carboxylate, an alkylene glycol monoalkyl ether and an alkyl lactate are preferred.
Any one of these solvents may be used alone, or two or more thereof may be used in combination. When two or more of these solvents are mixed together, it is preferred to mix a hydroxylated solvent with a non- hydroxylated solvent. The mass ratio of hydroxylated solvent to non-hydroxylated solvent is in the range of 1/99 to 99/1, preferably 10/90 to 90/10 and more
preferably 20/80 to 70/30.
The hydroxylated solvent is preferably an alkylene glycol monoalkyl ether or an alkyl lactate. The non- hydroxylated solvent is preferably an alkylene glycol monoalkyl ether carboxylate.
The content of solvent used in the whole amount of the composition of the present invention can be
appropriately regulated in accordance with the desired thickness of the film, etc. In general, -the solvent content is regulated so that the total solid content of the composition falls within the range of 0.5 to 5 massl, preferably 0.8 to 3 mass%, more preferably 0.8 to 2 massl and further more preferably 0.8 to 1.5 mass%.
[5] Other additive
(A) Surfactant
The composition of the present invention may further contain a surfactant. When a surfactant is contained, the surfactant is preferably a fluorinated and/or siliconized surfactant.
As such a surfactant, there can be mentioned
Megafac F176 or Megafac R08 produced by DIC Corporation, PF656 or PF6320 produced by OMNOVA SOLUTIONS, INC., Troy Sol S-366 produced by Troy Chemical Co., Ltd., Florad FC430 produced by Sumitomo 3M Ltd., polysiloxane polymer KP-341 produced by Shin-Etsu Chemical Co., Ltd., or the like.
Surfactants other than these fluorinated and/or siliconized surfactants can also be used. In
particular, the other surfactants include
polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers and the like.
Moreover, heretofore known surfactants can also be appropriately used. As useful surfactants, there can be mentioned, for example, those described in section [0273] et seq of US Patent Application Publication
No. 2008/0248425 Al .
One of these surfactants may be used alone, or two or more thereof may be used in combination. .... _ . When a surfactant is contained, the amount of surfactant added is preferably in the range of 0.01 to 1 massl, more preferably 0.01 to 0.5 mass% and most preferably 0.01 to 0.1 mass%, based on the total solids of the composition of the present invention (whole amount excluding the solvent).
(B) Other additive
In addition to the above-described components, a carboxylic acid, an onium salt of carboxylic acid, any of the dissolution inhibiting compounds of 3000 or less molecular weight described in, for example, Proceeding of SPIE, 2724,355 (1996), a dye, a plasticizer, a photosensitizer , a light absorber, an antioxidant, etc. can be appropriately incorporated in the composition of the present invention.
In particular, the carboxylic acid can be
appropriately used in order to enhance the performance on a basic substrate, such as a Cr film. It is
preferred for the carboxylic acid to be an aromatic carboxylic acid, such as benzoic acid or naphthoic acid
The content of carboxylic acid, based on the total solids of the composition, is preferably in the range of 0.01 to 10 massl, more preferably 0.01 to 5 massl and further more preferably 0.01 to 3 massl.
EXAMPLES
The present invention will be described in greater detail below by way of its examples. However, the gist of the present invention is in no way limited to these examples.
<Synthesis of polymeric compound (A) >
<Synthetic Example 1: synthesis of polymer-2> (Synthesis of chloroether compound)
A 500 ml round-bottomed flask was charged with 20.0 g of pivalaldehyde, 46.52 g of cyclohexanol , 2.70 g of camphorsulfonic acid, 20.0 g of anhydrous magnesium sulfate and 100 ml of hexane . The mixture was agitated at 25°C for an hour, and 20.0 g of anhydrous magnesium sulfate was further added thereto and agitated for an hour. Thereafter, 2.35 g of triethylamine was added to the mixture. The thus obtained reaction liquid was transferred into a separatory funnel, and the organic phase was washed with 100 ml of distilled water four times. The washed organic phase was dried over anhydrous magnesium sulfate, and concentrated. As a result of these operations, 49.6 g of acetal compound 2 was obtained.
Subsequently, a 100 ml round-bottomed flask was charged with 22.0 g of acetal compound 2 and 7.72 g of acetyl chloride, and the mixture was agitated at 45°C for three hours. Unreacted acetyl chloride was distilled off in vacuum, thereby obtaining a solution containing chloroether compound 2. The composition of obtained solution was determined by N R as follows. Chloroether compound 2: 46.1 mass%, cyclohexyl acetate 50.7 mass% and cyclohexanol: 3.2 mass%
J-H-NMR of chloroether compound 2 (CDCI3, ppm) δ: 1.03 (9H, s), 1.16-1.93 (10H, m) , 3.74 (1H, m) ,
5.48 (1H, s) .
Figure imgf000082_0001
Chloroether compound 2
(Synthesis of compound (polymer-2))
Poly (p-hydroxystyrene ) (VP-2500, produced by Nippon Soda Co.., Ltd.) as a phenolic compound amounting to 10.0 g was dissolved in 60 g of tetrahydrofuran (THF) . Thereafter, 8.85 g of triethylamine was added to the solution and agitated in an ice water bath. The above obtained chloroether compound 2 (12.46 g) was dropped into the reaction liquid, and agitated for four hours. Thereafter, distilled water was added to the mixture, thereby terminating the reaction. THF was distilled off in vacuum, and the reaction product was dissolved in ethyl acetate. The thus obtained organic phase was washed with distilled water five times, and the washed organic phase was dropped into 1.0 lit. of hexane . The thus obtained precipitate was separated by filtration, washed with a small amount of hexane, and dissolved in 45 g of PGMEA. Low-boiling solvents were removed from the obtained solution by means of an evaporator, thereby obtaining 58.4 g of a PGMEA
solution (20.0 mass%) of compound (polymer-2). With respect to the obtained compound (polymer-2), the mass average molecular weight (Mw: polystyrene- equivalent) , the number average molecular weight (Mn: polystyrene-equivalent) and the polydispersity index ( w/Mn, hereinafter also referred to as "PDI") thereof were calculated by GPC analysis (solvent: THF) .
Further, with respect to the compound (polymer-2), the component ratio (molar ratio) thereof was calculated by ^H-NMR analysis performed in the following manner.
(!H-N R analytical method)
The PGMEA solution of compound (polymer-2)
amounting to 0.5 g was diluted with 1.5 ml of ethyl acetate and 0.5 ml of triethylamine , and dropped into 50 g of hexane. The thus obtained precipitate was separated by filtration and dried. Then, 75 mg of obtained powder was dissolved in 1.1 g of D SO-d^. The resultant solution was analyzed by ^H-NMR.
The thus obtained ^H-N R chart of compound
(polymer-2) is shown in FIG. 1.
Figure imgf000083_0001
(Polymer-2)
<Synthetic Examples 2 and 3: syntheses of polymer- 1 and polymer-3>
Compounds P (polymer-1 and polymer-3) specified in Table 1 were synthesized in the same manner as in Synthetic Example' 1, except that employed phenolic compounds and chloroether compounds were appropriately changed. With respect to each of the obtained
compounds, the component ratio (molar ratio) , mass average molecular weight (Mw: polystyrene-equivalent) , number average molecular weight (Mn: polystyrene- equivalent) and polydispersity index (Mw/Mn) were calculated in the same manner as performed with respect to the compound (polymer-2).
The component ratio, mass average molecular weight (Mw) and polydispersity index (PDI) of each of the synthesized compounds P are listed in Table 1.
<Control compound>
Polymer-Xl and polymer-X2 specified in Table 1 were used as comparisons.
Figure imgf000085_0003
[Acid generator (B) ]
The compounds of the following formulae were usedid generators (B) .
Figure imgf000085_0001
Figure imgf000085_0002
The acid generators (B) can be synthesized by, for example, a method of sulfonating an aromatic compound with a cycloaliphatic skeleton. For example, the compound (B) of the present invention substituted with a cycloalkyl group (Cy) can be synthesized in
accordance with the following scheme.
Alicyc
Figure imgf000086_0001
or cycloalkene
Figure imgf000086_0002
The reaction of sulfonation can be performed with the use of a reagent selected from among chlorosulfonic acid (hydrolysis therewith) , sulfuric acid, fuming sulfuric acid, SO3, SO3 complex, sulfites and the like.
The counter cation can be converted to desired cation M+ by, for example, a conversion method using an ion exchange resin and common anion exchange methods described in, for example, JP-A-H6-184170.
[Basic compound]
The following compounds were used as basic compounds .
TBAH: tetrabutylammonium hydroxide,
TPI : 2 , 4 , 5-triphenylimidazole , and
DB : l,5-diazabicyclo[5.4.0] -5-nonene .
[Solvent]
The following solvents were used.
PGMEA: propylene glycol monomethyl ether acetate (boiling point 146°C),
PGME : propylene glycol monomethyl ether (boiling point 121°C) , and
EL: ethyl lactate (boiling point 154°C) .
[Other additive]
Additive 1: 2-hydroxy-3-naphthoic acid, and Additive 2: surfactant PF6320 (produced by OMNOVA SOLUTIONS, INC. ) .
<Preparation of resist>
Individual components of Table 2 below were dissolved in solvents of the same table, and the obtained solutions were each passed through a
polyethylene filter of 0.1 μιη pore size.
Table 2
Figure imgf000088_0001
<EB exposure evaluation 1: Examples 1 to 15 and Comparative Examples 1 to 6>
Resist patterns were formed from the compositions 1 to 9 specified in Table 2 in accordance with the following procedure. The particulars of the conditions employed in resist pattern formation are listed in Table 3.
[Resist coating and bake after coating]
Each of the prepared positive resist solutions was uniformly applied onto a silicon substrate having undergone a hexamethyldisilazane treatment by means of a spin coater, and dried by heating on a hot plate under the conditions specified in Table 3.
[Exposure ]
Each of the dried resist films was exposed to , electron beams by means of an electron beam lithography system (model JBX6000 manufactured by JEOL Ltd., acceleration voltage 50 KeV) while changing the
exposure amount so as to form a 20 to 15 nm line and space pattern (lengthwise 0.5 mm, 40 drawn lines) drawn at 1.25 nm intervals.
[Post-exposure bake]
After the exposure, the film was taken out from the electron beam lithography system and immediately baked on a hot plate under the conditions specified in
Table 3. The thickness of each of the . resultant resist films is listed in Table 3. [ Development ]
1. Shower development
By means of a shower developing equipment (model ADE3000S manufactured by Actes inc.), development was carried out by spraying an alkali developer (23°C) specified in Table 3 over the wafer being rotated at 50 rpm at a flow rate of 200 ml/min for a given period of time.
Thereafter, the film Was rinsed by spraying a rinse liquid (23°C) specified in Table 3 over the wafer being rotated at 50 rpm at a flow rate of 200 ml/min for a given period of time.
Finally, the wafer was dried by rotating the same at a high speed of 2500 rpm for 60 seconds.
2. Puddle development
By means of a shower developing equipment (model ADE3000S manufactured by Actes inc.), the wafer was covered with developer puddles by spraying an alkali developer (23°C) specified in Table 3 over the
wafer being rotated at 50 rpm at a flow rate of
200 ml/min for a period of five seconds. Then, the rotation of the wafer was discontinued, and the wafer was allowed to stand still for a period of time indicated in Table 3. Thus, development was
accomplished.
Thereafter, the film was rinsed by spraying a rinse liquid (23°C) specified in Table 3 over the wafer being rotated at 50 rpm at a flow rate of 200 ml/min for a given period of time.
Table 3
Figure imgf000092_0001
(Continued)
Table 3
Figure imgf000093_0001
TMAH: aq. soln. of tetramethylammonium hydroxide TEAH : aq. soln. of tetraethylammonium hydroxide TPAH: aq. soln. of tetra-n-propylammonium
hydroxide
TBAH: aq. soln. of tetra-n-butylammonium hydroxide
Surfinol 440: surfactant, produced by Nissin
Chemical Industry Co., Ltd.
The obtained resist patterns were evaluated with respect to the. following items. The particulars of the results are listed in Table 4.
[Sensitivity]
Each of the obtained patterns was observed by means of a scanning electron microscope (model S-9220, manufactured by Hitachi, Ltd. ) . The sensitivity was defined, as the exposure energy (yC/cm^) at which in the employment of a line width of 20 nm a line and a space could be separated- and resolved from each other at a ratio of 1:1.
[Resolving performance]
The state of 20 to 15 nm resolution was observed by means of a scanning electron microscope, and the obtained results are listed in Table 4. Resolution attained without any problem was denoted by A, and other states of resolution were denoted by B and C according to the following criteria. In the latter instance, a comment was noted. The smaller the size of resolved pattern, the higher the resolving performance.
[0264]
A: resolved,
B: partially non-resolved (but the line width could be measured) , and
C: non-resolved (measuring of line width was difficult) .
[Occurrence of development residue]
The occurrence of any residue in space areas was inspected by means of a scanning electron microscope. Non-occurrence of any residue in space areas was denoted by A, and other states of residue occurrence were denoted by B and C according to the following criteria. In the latter instance, a comment was noted [0265]
A: no residue,
B: residue partially found, and
C: residue markedly found.
[Shape]
The shape of each of the patterns of 20 nm line width formed in the exposure amount exhibiting the above sensitivity was observed by means of a scanning electron microscope (model S-4800 manufactured by Hitachi, Ltd. ) . Shape close to rectangle was denoted by A, and other shapes were denoted by B and C
according to the following criteria. In the latter instance, a comment on shape was noted.
[0266]
A rectangle,
B shape slightly deteriorated, and
C: shape markedly deteriorated. Table 4
Figure imgf000096_0001
*1: fell .
*2: partially fell
*3: slightly fell
*4 : partial disconnection
*5: partially torn
*6: film thinning
*7 : slight film thinning
*8 : overhanging head
* 9 : slightly overhanging head
*10 ■ residue
*11 . residue in space area
*12 poor dissolution
*13 ■ insufficient development <EB exposure evaluation 2: Examples 16 to 18>
Resist patterns were formed and evaluated in accordance with the same procedure as in the EB exposure evaluation 1 above, except that substrates indicated in Table 5 were used.
The employed resist compositions and pattern forming conditions are specified in Table 5, and the pattern evaluation results are listed in Table 6.
Table 5
Figure imgf000098_0001
^Substrate
Silicon substrate with Cr film: thickness of Cr film = 100 nm
Silicon substrate with DUV44: A silicon
substrate was coated with DUV44 (organic BARC produced by Brewer Science Inc.) in a film thickness of 60 nm and dried by heating at 200°C for 60 seconds, thereby obtaining the silicon substrate with DUV44.
Table 6
Figure imgf000100_0001
*1 fell
partially fell
*3 partially torn
<EUV exposure evaluation: Examples 19 and 20> Resist patterns were formed in accordance with the following procedure. The pattern forming conditions and pattern evaluation results are listed in Table 7 and Table 8, respectively.
[Resist coating]
Each of the compositions 1 and 3 specified in Table 1 was uniformly applied onto a silicon substrate having undergone a hexamethyldisilazane treatment by means of a spin coater, and dried by heating on a hot plate under the conditions specified in Table 7.
[Exposure]
Each of the dried resist films was exposed to EUV light (wavelength 13 nm) through a 30 nm line width 1:1 line and space mask pattern while changing the exposure amount .
[Post-exposure bake]
After the exposure, the film was taken out from the EUV exposure apparatus and immediately baked on a hot plate under the conditions specified in Table 7. The thickness of each of the resultant resist films is listed in Table 7.
[ Development ]
The thus baked resist films were developed in accordance with the same procedure as in the EB exposure evaluation 1 above.
The obtained resist patterns were evaluated with respect to the following items.
[ Sensitivity]
Each of the obtained patterns was observed by means of a scanning electron microscope (model S-9380, manufactured by Hitachi, Ltd. ) . The sensitivity was defined as the exposure energy (mJ/cm2) at which in the employment of a line width of 30 nm a line and a space could be separated and resolved from each other at a ratio of 1:1.
[Shape]
The shape of each of the patterns of 30 nm line width formed in the exposure amount exhibiting the above sensitivity was observed by means of a scanning electron microscope (model S-4800, manufactured by Hitachi, Ltd. ) . ■
[Occurrence of development residue]
The occurrence of any development residue was inspected by the same method as in the EB exposure evaluation 1 above.
Tjable 7
Figure imgf000103_0001
Table 8
Figure imgf000104_0001
<Evaluation of dry etching>
Etching evaluation was carried out in accordance with the following procedure. The results are listed in Table 9.
[Resist coating]
Each of the resist solutions specified in Table 9 was uniformly applied onto a silicon substrate having undergone a hexamethyldisilazane treatment by means of a spin coater, and dried by heating on a hot plate under the conditions specified in Table 9. Thus, substrates each with a 25 nm-thick resist film were obtained .
[Etching evaluation]
The above substrates with resist films were evaluated with respect to etching performance under the conditions specified below.
Table 9
Figure imgf000104_0002
Etching apparatus: U-621 (manufactured by Hitachi High-Technologies Corporation) ; Gas flow rate (ml/min) : C4 g/02 /Argon =
20/40/1000;
Pressure: 2 Pa, Temp.: 20°C, Power: 500 W, Coil current: 10.6/5.6 A; and
Etched time: 10 seconds.
It is apparent from the obtained evaluation results that the method of forming a pattern according to the present invention can find appropriate
application in the process for producing a photoresist or nanoimprint mold master.

Claims

C L A I M S
1. A method of forming a pattern, including forming a film of an actinic-ray- or radiation- sensitive resin composition on a substrate, exposing the film to actinic rays or radiation and developing the exposed film with a developer to thereby obtain a fine pattern, characterized in that the actinic-ray- or radiation-sensitive resin composition comprises a polymeric compound (A) containing any of repeating units of general formula (I) below, and that the developer comprises tetrapropylammonium hydroxide,
Figure imgf000106_0001
in which
each of Rni, o2 anc Ro3 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, provided that RQ3 may be bonded to Ar]_ to thereby form a ring, which RQ3 represents an alkylene group,
A∑i represents a (n+l)-valent aromatic ring group, provided that Ar^, when bonded to RQ3 to thereby form a ring, represents a (n+2)-valent aromatic ring group, n is an integer of 1 to 4, and
Y, when n≥2 each independently, represents a hydrogen atom or a group leaving when acted on by an acid, provided that at least one of Y' s is a group leaving when acted on by an acid, which group is any of groups of general formula (II) below,
— C-O-M-Q (II)
I
L2
in which
each of L]_ and L2 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group,
M represents a single bond or a bivalent
connecting group, and
. Q represents an alkyl group, a cycloalkyl group, an alicyclic group, an aromatic ring group, an amino group, an ammonium group, a mercapto group, a cyano group or an acyl group, provided that each of the alicyclic group and aromatic ring group may contain a heteroatom,
provided that L]_ may be bonded to M and/or Q to thereby form a ring.
2. The method according to claim 1, characterized in that the obtained pattern is positive, and that the developer is an alkali developer.
3. The method according to claim 2, characterized in that the alkali developer comprises . alkali
components, 70 mol% or more of which are comprised of tetrapropylammonium hydroxide.
4. The method according to claim 1, characterized by further including baking performed between the exposure and the development.
5. The method according to claim 1, characterized in that the exposure is performed to electron beams or EUV light.
6. The method according to claim 1, characterized in that the repeating units of general formula (I) are repeating units of general formula (III) below,
Figure imgf000108_0001
in which
R21 represents a hydrogen atom or a methyl group, Ar^l represents a bivalent aromatic ring group, each of Rll, Rl2 and R!3 independently represents an organic group with a carbon atom as an atom bonded to C in - (CR1:1-R12R13) , provided that at least two of Rll, Rl2 and R!3 may be bonded to each other to thereby form a ring,
represents a single bond or a bivalent connecting group, and
Q11 represents an alkyl group, a cycloalkyl group or an aromatic ring group.
7. The method according to claim 1, characterized in that the actinic-ray- or radiation-sensitive resin composition further comprises a compound (B) that when exposed to actinic rays or radiation, generates an acid and a basic compound (C) .
8. A photomask produced by a process comprising forming a pattern on a substrate in accordance with the method according to claim 1 and etching a surface of the substrate by use of the pattern.
9. A nanoimprint mold master produced by a process comprising forming a pattern on a substrate in accordance with the method according to claim 1 and etching a surface of the substrate by use of the pattern .
PCT/JP2013/060142 2012-03-28 2013-03-27 Method of forming pattern, photomask and nanoimprint mold master WO2013147315A1 (en)

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JPH1078658A (en) * 1996-09-05 1998-03-24 Fujitsu Ltd Chemical amplification type resist composition and resist pattern forming method
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JP2009229572A (en) * 2008-03-19 2009-10-08 Tokyo Ohka Kogyo Co Ltd Detergent for lithography and method for forming resist pattern
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