Classifications

• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
• • 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
• • 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
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
• • 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
  • G03F7/20—Exposure; Apparatus therefor
• • 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
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70008—Production of exposure light, i.e. light sources
  • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources

Definitions

• the present invention relates to a radiation-sensitive composition, a pattern forming method, and a radiation-sensitive acid generator.
• Photolithography technology uses a resist composition to form fine circuits in semiconductor elements.
• a coating of the resist composition is exposed to radiation through a mask pattern to generate an acid, which is then catalyzed by a reaction that creates a difference in the solubility of the resin in alkaline or organic solvent-based developers between exposed and unexposed areas, forming a resist pattern on a substrate.
• the above photolithography technology promotes pattern miniaturization by using short-wavelength radiation such as ArF excimer lasers, or by combining this radiation with liquid immersion lithography.
• short-wavelength radiation such as ArF excimer lasers
• liquid immersion lithography As a next-generation technology, efforts are being made to use even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet), and resist materials containing compounds that generate acids with structures that increase the efficiency of absorbing such radiation are also being considered (Patent No. 4701231).
• next-generation technologies also require resist performance that is equal to or better than conventional performance in terms of sensitivity, critical dimension uniformity (CDU), which is an index of uniformity of line width and hole diameter, and development defects.
• CDU critical dimension uniformity
• the present invention aims to provide a radiation-sensitive composition and a pattern formation method capable of forming a resist film that exhibits sufficient levels of sensitivity and CDU and suppresses development defects when next-generation technology is applied.
• Another aim of the present invention is to provide a radiation-sensitive acid generator that can be applied to the radiation-sensitive composition.
• the present invention comprises: A polymer (A) including a structural unit (I) having an acid dissociable group; A solvent (C) and
• the present invention relates to a radiation-sensitive composition which satisfies at least one of the following (i) and (ii): (i) A radiation-sensitive acid generator (B) containing a first organic acid anion and a first onium cation, wherein the first onium cation is an onium cation containing a halogen-free electron-withdrawing group that does not contain a halogen atom, and the first organic acid anion is a sulfonate anion containing an iodine atom.
• the polymer (A) is a radiation-sensitive acid-generating polymer (A1) containing a structural unit (IV) having a second organic acid anion and a second onium cation, the second onium cation is an onium cation containing a halogen-free electron-withdrawing group that does not contain a halogen atom, and the second organic acid anion is a sulfonate anion containing an iodine atom.
• the radiation-sensitive composition can construct a resist film that satisfies the sensitivity and CDU and suppresses the occurrence of development defects.
• the reason for this is unclear, it is presumed to be as follows.
• the first onium cation of the radiation-sensitive acid generator (B) or the second onium cation of the radiation-sensitive acid-generating polymer (A1) has an electron-withdrawing group and reacts efficiently with electrons, which is thought to improve sensitivity and lithography performance.
• the electron-withdrawing group of the onium cation does not contain a halogen atom, the onium cation is highly hydrophilic and has an increased affinity with an alkaline developer, thereby suppressing the occurrence of development defects.
• the first organic acid anion of the radiation-sensitive acid generator (B) or the second organic acid anion of the radiation-sensitive acid-generating polymer (A1) is a sulfonate anion containing an iodine atom, which increases the electron yield and, as a result, the radiation-sensitive composition is made highly sensitive.
• the acid diffusion can be controlled by the molecular weight of the iodine atom, and the CDU can be improved. It is presumed that the combined effects of these two factors enable the above-mentioned resist performance and development defect suppression to be exhibited.
• the present invention provides a method for producing a pharmaceutical composition comprising the steps of: a step of directly or indirectly applying the radiation-sensitive composition to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.
• the pattern formation method uses the above-mentioned radiation-sensitive composition, which is capable of forming a resist film that has excellent sensitivity and CDU and suppresses the occurrence of development defects, so that a high-quality resist pattern can be efficiently formed.
• the present invention provides a method for producing a pharmaceutical composition comprising the steps of: an onium cation containing an electron-withdrawing group that does not contain a halogen atom; and a sulfonate anion containing an iodine atom.
• the radiation-sensitive composition according to this embodiment contains a polymer (A) and a solvent (C) and satisfies at least one of the above (i) and (ii).
• the radiation-sensitive composition contains a radiation-sensitive acid generator (B) having a specific structure
• the polymer (A) contains a radiation-sensitive acid generator having a specific structural unit.
• the radiation-sensitive composition may contain other optional components as long as they do not impair the effects of the present invention. or the polymer (A) is a radiation-sensitive acid-generating polymer (A1) containing a specific structural unit, A resist film obtained by using the composition can exhibit higher levels of sensitivity and CDU, and can suppress the occurrence of development defects.
• the polymer (A) is an aggregate of polymer chains containing a structural unit (I) having an acid-dissociable group (hereinafter, this aggregate is also referred to as a "base polymer").
• the polymers constituting the polymer (A) may contain the structural unit (I) as a whole.
• the polymer (A) may also contain a structural unit other than the structural unit (I).
• the polymer (A) may be a polymer having an acid generating structure that generates acid upon exposure (radiation-sensitive acid generating polymer (A1)), or may be a polymer not having an acid generating structure.
• the polymer having an acid generating structure that generates acid upon exposure is an assembly of polymer chains that includes a structural unit (I) having an acid-dissociable group, and a structural unit (IV) having a second organic acid anion and a second onium cation (hereinafter, this polymer is also referred to as the "base polymer (A1)"), and is a component that generates acid upon exposure.
• the structural unit (I) and the structural unit (IV) may be included in the same polymer chain, or the structural unit (I) may be included in one polymer chain and the structural unit (IV) may be included in another polymer chain.
• the entire polymer that constitutes the radiation-sensitive acid-generating polymer (A1) may include the structural unit (I) and the structural unit (IV).
• the radiation-sensitive acid-generating polymer (A1) may include structural units other than the structural unit (I) and the structural unit (IV).
• a form in which an onium salt structure is incorporated as part of a polymer is referred to as a "radiation-sensitive acid-generating polymer," and a low-molecular-weight form in which an onium salt structure exists as a compound by itself (isolated from a polymer) is referred to as a "radiation-sensitive acid generator.”
• the term "acid dissociable group” refers to a group that replaces a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and dissociates under the action of an acid.
• the acid generated from the radiation-sensitive acid generator (B) or the radiation-sensitive acid-generating polymer (A1) upon exposure dissociates the acid dissociable group in the structural unit (I) to generate a carboxy group or the like. This creates a difference in solubility in a developer between the exposed and unexposed areas of the resist film, making it possible to form a pattern.
• the above polymer (A) preferably contains an iodine atom, and more preferably contains an iodine-substituted aromatic ring structure.
• the structural unit (I) is a structural unit having an acid dissociable group.
• the structural unit (I) is not particularly limited as long as it contains an acid dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond.
• a structural unit represented by the following formula (A1) (hereinafter also referred to as "structural unit (I-1)) is preferred.
• R A is a hydrogen atom, a fluorine atom, an alkyl group having 1 to 10 carbon atoms, or a fluorinated alkyl group having 1 to 10 carbon atoms, and the alkyl group and the fluorinated alkyl group may have one or more -O-, -CO-, or a linking group combining these between carbon atoms.
• R A1 is a hydrogen atom, or a monovalent hydrocarbon group having 1 to 20 carbon atoms.
• R A2 and R A3 each independently represent a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these groups together with the carbon atom to which they are bonded.
• m1 and m2 each independently represent 0 or 1. However, when m1 is 1, m2 is 1. When m1 is 0, L 1 represents a single bond or a divalent linking group, and when m1 is 1, L 1 represents a divalent linking group.
• some or all of the hydrogen atoms on the carbon atoms may be substituted with substituents such as halogen atoms.
• Examples of the divalent linking group represented by L1 include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, a cycloalkenediyl group, an arenediyl group, a group containing -CO-, -CS-, -O-, -S-, -SO 2 -, -NR'- or a combination of two or more of these between the carbon-carbon bonds of these groups, or a group combining these.
• R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.
• Some or all of the hydrogen atoms of these groups may be substituted with a substituent such as a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group; an alkoxy group; an alkoxycarbonyl group; an alkoxycarbonyloxy group; an acyl group; an acyloxy group, or a group in which the hydrogen atoms of these groups are substituted with a halogen atom.
• a substituent such as a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group; an alkoxy group; an alkoxycarbonyl group; an alkoxy
• the alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, or a 2,2-propanediyl group.
• cycloalkanediyl group examples include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups; and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups.
• the cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.
• alkenediyl group examples include ethenediyl, propenediyl, and butenediyl groups.
• the alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.
• Examples of the arenediyl group include a benzenediyl group, a toluenediyl group, and a naphthalenediyl group.
• the arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.
• Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R A1 include a chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
• Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R A1 to R A3 include a monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms.
• Examples of the monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, an n-pentyl group, an isopentyl group, and a neopentyl group.
• Examples of the monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms include alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.
• the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R A1 to R A3 may be a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group.
• the monocyclic saturated hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
• Examples of the polycyclic saturated hydrocarbon group include bridged alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group.
• Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group.
• Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.
• the bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms that constitute the alicyclic ring are linked via a linking group containing one or more carbon atoms.
• R A1 is preferably a hydrogen atom, a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group.
• divalent alicyclic group having 3 to 20 carbon atoms constituted by R A2 and R A3 taken together with the carbon atom to which they are bonded a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.
• R A2 and R A3 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms constituted by R A2 and R A3 taken together with the carbon atom to which they are bonded, and more preferably an alkyl group having 1 to 4 carbon atoms, or a cycloalkanediyl group or cycloalkenediyl group constituted by R A2 and R A3 taken together with the carbon atom to which they are bonded.
• L1 is preferably a single bond or an arenediyl group
• m2 is preferably 1.
• Examples of the structural unit (I-1) include structural units represented by the following formulas (1-1) to (1-4).
• R A and R A1 to R A3 are defined the same as in the above formula (A1).
• i is an integer of 1 to 4.
• l is an integer of 0 to 2
• j is an integer of 0 to 9, satisfying 0 ⁇ j ⁇ 2l+5.
• k1 is an integer of 0 to 7, and k2 is an integer of 1 to 3.
• the substituents in L1 in the above formula (A1) can be suitably adopted as X.
• a halogen atom or an alkyl group is preferable, and an iodine atom or a methyl group is more preferable.
• j or k1 is 2 or more, the multiple Xs present may be the same or different.
• R A1 is preferably a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a t-butyl group
• R A2 and R A3 are preferably a methyl group, an ethyl group, or a t-butyl group.
• the structural unit (I) include, but are not limited to, structures represented by the following formulas. Among those shown below, for structures having an iodine-substituted aromatic ring structure, structures in which the iodine atom in the following formula is replaced with an atom or group other than an iodine atom, such as a hydrogen atom or other substituent, can also be suitably used.
• R A has the same meaning as in formula (A1) above.
• R A has the same meaning as in formula (A1) above.
• the base polymer may contain one or a combination of two or more types of structural unit (I).
• the lower limit of the content of the structural unit (I) (the total content when multiple types are included) is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%, based on all structural units constituting the base polymer (or base polymer (A1)).
• the upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%.
• the polymer (A) preferably further contains a structural unit (II) having a phenolic hydroxyl group.
• a structural unit (II) having a phenolic hydroxyl group examples include, but are not limited to, those shown below.
• R A is the same as above.
• the lower limit of the content of the structural unit (II) (the total content when multiple types are contained) is preferably 15 mol%, more preferably 20 mol%, even more preferably 25 mol%, and particularly preferably 30 mol%, based on all structural units constituting the base polymer (or base polymer (A1)).
• the upper limit of the content is preferably 70 mol%, more preferably 60 mol%, even more preferably 55 mol%, and particularly preferably 50 mol%.
• the polymer (A) may further contain another structural unit (III) containing a polar group such as an alcoholic hydroxyl group, a carboxyl group, a lactone ring, a sultone ring, an ether group, an ester group, a carbonyl group, or a cyano group.
• a polar group such as an alcoholic hydroxyl group, a carboxyl group, a lactone ring, a sultone ring, an ether group, an ester group, a carbonyl group, or a cyano group.
• monomers that provide the structural unit (III) include, but are not limited to, those shown below.
• R A is the same as above.
• the lower limit of the content ratio of the structural unit (III) (the total content ratio when multiple types are contained) is preferably 5 mol %, more preferably 8 mol %, and even more preferably 10 mol %, based on all structural units constituting the base polymer (or base polymer (A1)).
• the upper limit of the content ratio is preferably 40 mol %, more preferably 30 mol %.
• the polymer (A) may contain a structural unit (IV) having a second organic acid anion and a second onium cation.
• a structural unit (IV) having an onium salt structure By incorporating the structural unit (IV) having an onium salt structure as a part of the polymer (A), the polymer (A) can be used as a "radiation-sensitive acid-generating polymer (A1)".
• the form of organic acid anion and onium cation contained in the structural unit (IV) of the base polymer is not particularly limited, and the base polymer may have the above organic acid anion as a side chain portion, or may have the onium cation as a side chain portion. Having as a side chain portion means that the corresponding organic acid anion or onium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.
• the organic acid anion is bonded to the main chain as a side chain structure of the base polymer
• the onium cation is ionically bonded to the organic acid anion as a counter ion of the organic acid anion.
• the organic acid anion is ionically bonded to the onium cation as a counter ion of the onium cation.
• the base polymer has the above organic acid anion as a side chain portion.
• the second organic acid anion is a sulfonate anion containing an iodine atom, and is preferably a sulfonate anion containing an iodine-substituted aromatic ring structure.
• the second organic acid anion preferably has a sulfonate anion, and an electron-withdrawing group such as a fluorine atom or a fluorinated hydrocarbon group is bonded to a carbon atom adjacent to the sulfonate anion. This makes it possible to sufficiently increase the strength of the acid generated by exposure to a level required for dissociation of the acid-dissociable group.
• the structure of the second organic acid anion may be a sulfonate anion containing an iodine atom, and other structures are not particularly limited, but preferably contain, for example, -O-, -CO-, a cyclic structure, or a combination thereof. Such combinations also include structures in which -O- or -CO- is incorporated as a portion forming a ring in a cyclic structure (heterocyclic structure).
• the cyclic structure may be a monocyclic ring, a polycyclic ring, or a combination thereof.
• the cyclic structure may be an alicyclic structure, an aromatic ring structure, a heterocyclic structure, or a combination thereof.
• the cyclic structures may be bonded to a chain structure, or two or more cyclic structures may form a condensed ring structure or a bridged ring structure.
• a divalent heteroatom-containing group may be present between the carbon-carbons forming the skeleton of the cyclic structure or the chain structure, and some or all of the hydrogen atoms on the carbon atoms of the cyclic structure or the chain structure may be substituted with other substituents.
• the second organic acid anion preferably has at least one cyclic structure selected from the group consisting of alicyclic structures and aromatic ring structures.
• alicyclic structure a structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in R A2 and R A3 in formula (A1) can be suitably adopted.
• the aromatic ring structure is not particularly limited as long as it is a ring structure having aromaticity.
• aromatic rings include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, a perylene ring, and a coronene ring, and heteroaromatic rings such as a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, a carbazole ring, and
• heterocyclic structure examples include: Oxygen atom-containing alicyclic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; Nitrogen atom-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thietane, thiolane, and thiane; Alicyclic heterocyclic structures containing multiple types of heteroatoms, such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane; Oxygen atom-containing aromatic heterocyclic structures such as furan and benzofuran; Nitrogen atom-containing aromatic heterocyclic structures such as pyrrole, pyrazole, and triazine; Sulfur-containing aromatic heterocyclic structures such as thiophene; Aromatic heterocyclic structures containing multiple types of hetero hetero
• the heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal structure, or a combination thereof.
• a monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R A2 and R A3 in formula (A1) above, can be suitably used.
• heteroatoms constituting the divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms.
• halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.
• the structural unit that provides the second organic acid anion is preferably a structural unit represented by the following formula (a1):
• R A is a hydrogen atom or a methyl group.
• X 1 is a single bond or an ester group.
• X 2 is a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, an arylene group having 6 to 10 carbon atoms, or a combination thereof, and a part of the methylene group constituting the alkylene group may be substituted with an ether group, an ester group, or a lactone ring-containing group.
• X 3 is a single bond, an ether group, an ester group, a linear or branched alkylene group having 1 to 12 carbon atoms, or a cyclic cycloalkylene group having 3 to 12 carbon atoms, and a part of the methylene group constituting the alkylene group may be substituted with an ether group or an ester group.
• a part or all of the hydrogen atoms possessed by X 2 and X 3 may be substituted with a hetero atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.
• At least one of X 2 and X 3 contains an iodine atom, and it is preferable that X 2 contains an iodine-substituted aromatic ring structure.
• Rf 1 to Rf 4 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group.
• the monovalent hydrocarbon group having 1 to 20 carbon atoms in X2 and X3 is preferably an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 20 carbon atoms.
• Some or all of the hydrogen atoms in these groups may be substituted with a heteroatom-containing group such as a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, an amide group, a nitro group, a sultone group, a sulfone group, or a sulfonium salt-containing group, an alkoxy group, or an alkoxycarbonyl group.
• Some of the methylene groups constituting these groups may be substituted with an ether group, an ester group, a carbonyl group, a carbonate group, or a sulfonate ester group.
• the structural units that provide the second organic acid anion are preferably represented by the following formulas (a1-1), (a2-1), and (a3-1), respectively.
• R A , Rf 1 to Rf 4 , X 1 and s1 are defined as in formula (a1).
• R 48 is a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms, a halogen atom other than iodine, a hydroxy group, a linear, branched or cyclic alkoxy group having 1 to 4 carbon atoms, or a linear, branched or cyclic alkoxycarbonyl group having 2 to 5 carbon atoms.
• m is an integer of 1 to 4.
• n is an integer of 0 to 3, with the proviso that 0 ⁇ m+n ⁇ 4.
• s is an integer of 1 to 5.
• Monomers that provide the above structural units include, but are not limited to, those shown below.
• R A has the same meaning as in formula (a1) above.
• the second onium cation can be the same as the first onium cation of the radiation-sensitive acid generator (B) described below.
• the structural unit (IV) there can be mentioned one having the above-mentioned second onium cation as a counter ion of the anion of the structural unit that gives the above-mentioned second organic acid anion.
• the lower limit of the content of structural unit (IV) (the total content when multiple types are contained) is preferably 1 mol %, more preferably 3 mol %, and even more preferably 5 mol %, based on all structural units constituting base polymer (A1).
• the upper limit of the content is preferably 30 mol %, more preferably 25 mol %, and even more preferably 20 mol %.
• a monomer that gives the structural unit described above may be polymerized in an organic solvent by adding a radical polymerization initiator and heating the monomer.
• a known polymerization initiator may be used for the polymerization.
• acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy groups may be deprotected by the above-mentioned alkaline hydrolysis to form hydroxystyrene units or hydroxyvinylnaphthalene units. Also, polymerization may be carried out without protecting the hydroxyl groups.
• the lower limit of the weight average molecular weight (Mw) of the polymer (A) in terms of polystyrene, as determined by gel permeation chromatography (GPC) using THF as a solvent, is preferably 2,000, more preferably 4,000.
• the upper limit of the Mw is preferably 30,000, more preferably 15,000. If the Mw is within the above range, the resist material has good pattern formability and heat resistance.
• the molecular weight distribution (Mw/Mn) of the polymer (A) is broad, the presence of low-molecular-weight and high-molecular-weight polymers may result in foreign matter being found on the pattern after exposure, or the shape of the pattern may be deteriorated. As the pattern rules become finer, the effects of Mw and molecular weight distribution tend to become greater. Therefore, in order to obtain a resist material suitable for use with fine pattern dimensions, it is preferable that the molecular weight distribution of the polymer (A) is narrow, ranging from 1.0 to 2.0, and particularly from 1.0 to 1.8.
• the polymer (A) may contain two or more polymers with different composition ratios, Mw, and molecular weight distributions.
• the lower limit of the content of polymer (A) in the radiation-sensitive composition is preferably 40% by mass, more preferably 50% by mass, and even more preferably 60% by mass, based on the amount of the polymer (A) other than the solvent (C) contained in the radiation-sensitive composition.
• the upper limit of the content is preferably 99% by mass, and more preferably 95% by mass.
• the radiation-sensitive acid generator (B) contains a first organic acid anion and a first onium cation, the first onium cation being an onium cation containing a halogen-free electron-withdrawing group that does not contain a halogen atom, and the first organic acid anion being a sulfonate anion containing an iodine atom.
• the radiation-sensitive composition of the present invention contains at least one of the radiation-sensitive acid-generating polymer (A1) or the radiation-sensitive acid generator (B), and may contain both.
• the first onium cation contains a halogen-free electron-withdrawing group that does not contain a halogen atom.
• the halogen-free electron-withdrawing group may be any group that has electron-withdrawing properties and does not contain a halogen atom, and is preferably at least one electron-withdrawing group selected from the group consisting of CN, COOR 11 , NO 2 , COR 12 , SOR 13 , and SO 2 R 14 (wherein R 11 to R 14 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms).
• the first onium cation may contain a halogen-free electron-withdrawing group, and may contain a halogen-containing electron-withdrawing group in addition to the halogen-free electron-withdrawing group.
• halogen-containing electron-withdrawing groups include halogen atoms such as fluorine atoms and iodine atoms, and halogen atom-containing groups.
• R 11 to R 14 As the monovalent hydrocarbon group having 1 to 12 carbon atoms represented by R 11 to R 14 above, among the specific examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms in R A1 of formula (A1) above, those having 1 to 12 carbon atoms can be suitably used. Among these, from the viewpoint of development defects, R 11 to R 14 are preferably an alkyl group having 1 to 6 carbon atoms, or a group having a divalent heteroatom-containing group between the carbon atoms of this alkyl group.
• CN COOR 11 (R 11 is an alkyl group having 1 to 6 carbon atoms), NO 2 , COR 12 (R 12 is an alkyl group having 1 to 6 carbon atoms), and SO 2 R 14 (R 14 is an alkyl group having 1 to 6 carbon atoms) are preferred.
• the number of the non-halogen-containing electron-withdrawing groups in the onium cation is preferably 1 to 5, and more preferably 1 to 4.
• the number of non-halogen-containing electron-withdrawing groups in the above range is preferable from the viewpoint of hydrophilicity.
• the first onium cation is preferably a sulfonium cation or an iodonium cation, and more specifically, is preferably a cation represented by the following formula (1) or (2):
• Ar 1 , Ar 2 and Ar 3 each independently represent a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
• Z 1 , Z 2 and Z 3 are each independently the above-mentioned halogen-free electron-withdrawing group.
• R 101 , R 102 and R 103 are each independently a monovalent organic group (excluding non-halogen-containing electron-withdrawing groups), a halogen atom, a hydroxyl group or an amino group, or two of R 101 , R 102 and R 103 are linked to form a ring structure.
• R 101 , R 102 and R 103 When a plurality of R 101 , R 102 and R 103 are present, the plurality of R 101 , R 102 and R 103 are the same or different from each other.
• p1, p2, and p3 each independently represent an integer of 0 to 3, provided that p1+p2+p3 is 1 or more.
• q1, q2, and q3 each independently represent an integer of 0 to 2.
• p1+q1, p2+q2, and p3+q3 are each 5 or less.
• Ar 4 and Ar 5 each independently represent a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
• Z4 and Z5 are each independently the above-mentioned halogen-free electron-withdrawing group.
• R 104 and R 105 are each independently a monovalent organic group (excluding non-halogen-containing electron-withdrawing groups), a halogen atom, a hydroxyl group, or an amino group. When a plurality of R 104 and R 105 are present, the plurality of R 104 and R 105 are the same or different from each other.
• p4 and p5 each independently represent an integer of 0 to 3, provided that p4+p5 is 1 or more.
• q4 and q5 each independently represent an integer of 0 to 2.
• p4+q4 and p5+q5 are each 5 or less.
• the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by Ar 1 to Ar 5 can be suitably used as the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by Ar 1 to Ar 5 .
• the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R A1 in the above formula (A1) can be suitably used as the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by Ar 1 to Ar 5 .
• Z 1 to Z 5 are the above-mentioned halogen-free electron-withdrawing groups, and Z 1 to Z 5 are preferably CN, COOR 11 (R 11 is an alkyl group having 1 to 6 carbon atoms), NO 2 , COR 12 (R 12 is an alkyl group having 1 to 6 carbon atoms), or SO 2 R 14 (R 14 is an alkyl group having 1 to 6 carbon atoms).
• Examples of the monovalent organic groups represented by R 101 to R 105 include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups having a divalent heteroatom-containing group between the carbon atoms of this hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with monovalent substituents, and combinations of these, etc.
• Examples of the monovalent substituents include the substituent in L 1 in the above formula (A1), -NR Y4 R Y5 (R Y4 and R Y5 are the same or different and are hydrogen atoms or monovalent hydrocarbon groups), and groups in which the hydrogen atoms of these groups have been substituted with halogen atoms, etc.
• the monovalent hydrocarbon group having 1 to 20 carbon atoms for R 101 to R 105 and the monovalent hydrocarbon group represented by R Y4 and R Y5 can be suitably used.
• heteroatom constituting the divalent heteroatom-containing group and the divalent heteroatom-containing group those exemplified in the structural unit (IV) above can be suitably used.
• two of R 101 , R 102 and R 103 may be bonded to form a ring (i.e., a heterocycle containing a sulfur atom).
• a ring i.e., a heterocycle containing a sulfur atom
• the divalent linking group include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO 2 -, an alkylene group, a cycloalkylene group, an alkenylene group or a combination of two or more of these, and those having a total carbon number of 20 or less are preferable.
• R 101 , R 102 and R 103 are bonded to each other to form a ring
• a plurality of R 101 may be bonded to each other to form a ring
• a plurality of R 102 may be bonded to each other to form a ring
• a plurality of R 103 may be bonded to each other to form a ring.
• Such an example includes, for example, an embodiment in which two R 101 are bonded to each other to form a naphthalene ring together with the benzene ring to which they are bonded.
• p1, p2, and p3 are each independently an integer from 0 to 3, and p1+p2+p3 is 1 or greater, and preferably 2 or greater. In addition, p1+p2+p3 is preferably 6 or less, and more preferably 4 or less.
• sulfonium cation represented by the above formula (1) include the following.
• the fluorine atom or iodine atom in the onium cation below may be replaced with a hydrogen atom or other substituent, and the hydrogen atom on the aromatic ring may be replaced with an iodine atom, a fluorine atom, a group containing these atoms, or another substituent.
• iodonium cations include the following.
• the hydrogen atoms on the aromatic rings in the onium cations below may be substituted with iodine atoms, fluorine atoms, groups containing these atoms, or other substituents.
• the first organic acid anion is a sulfonate anion containing an iodine atom, and is preferably represented by, for example, the following formula (A-1).
• R 1K is preferably a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, an ethoxy group, etc., and more preferably a hydroxy group or an ethoxy group.
• rk is an integer from 0 to 2
• qk is an integer from 1 to 5
• R 2K is a single bond, an ether bond, an ester bond, or an alkylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond.
• the alkylene group may be linear, branched, or cyclic.
• L 1 K is a divalent linking group.
• the divalent linking group in L 1 of the above formula (A1) can be suitably adopted.
• Rf 1K and Rf 2K each independently represent a hydrogen atom, a fluorine atom or a trifluoromethyl group, and it is preferable that Rf 1K and Rf 2K are both fluorine atoms.
• pk is an integer between 0 and 5.
• Examples of the first organic acid anion represented by the above formula (A-1) include, but are not limited to, those shown below.
• the radiation-sensitive acid generator (B) includes any combination of the first organic acid anion and the first onium cation. Among these, the following are preferred.
• the radiation-sensitive acid generator (B) can be synthesized by a known method, particularly a salt exchange reaction. As long as the effect of the present invention is not impaired, a known radiation-sensitive acid generator other than the radiation-sensitive acid generator (B) can also be used in combination.
• the lower limit of the content of the radiation-sensitive acid generator (B) (total when multiple types are used) is preferably 10 parts by mass, more preferably 20 parts by mass, and even more preferably 30 parts by mass, per 100 parts by mass of the polymer (A).
• the upper limit of the content is preferably 80 parts by mass, more preferably 75 parts by mass, and even more preferably 70 parts by mass, per 100 parts by mass of the polymer (A). This allows excellent sensitivity and CDU to be exhibited when forming a resist pattern.
• the radiation-sensitive composition may contain a radiation-sensitive acid generator (B).
• the radiation-sensitive composition preferably contains an acid diffusion controller (D).
• the acid diffusion controller (D) contains a third organic acid anion and a third onium cation, and generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator (B) or the radiation-sensitive acid-generating polymer (A1) upon irradiation with radiation.
• the acid diffusion controller (D) containing the third organic acid anion and the third onium cation is preferably represented by the following formula (8-1) or the following formula (8-2).
• J + is a sulfonium cation
• U + is an iodonium cation
• E - and Q - are each preferably at least one selected from the group consisting of R 8 SO 3 - , R 8 COO - , and (R 8 SO 2 )N -, and more preferably R 8 COO - .
• examples of the compound include a compound represented by the above formula (8-3) containing a sulfonium cation and an anion in the same molecule, and a compound represented by the above formula (8-4) containing an iodonium cation and an anion in the same molecule.
• the above R 8 is a monovalent organic group in the cases of the above formulas (8-1) and (8-2), and is a single bond or a divalent organic group in the cases of the above formulas (8-3) and (8-4).
• the third organic acid anion is preferably an organic acid anion containing an iodine atom, and more preferably an organic acid anion containing an iodine-substituted aromatic ring structure.
• the third organic acid anion may, for example, be an anion represented by the following formula.
• an anion represented by the following formula represented by the following formula.
• structures in which the iodine atom in the following formula is replaced with an atom or group other than an iodine atom, such as a hydrogen atom or other substituent, can also be suitably used.
• Examples of the sulfonium cation for J + include the onium cation represented by formula (1) or (2) of the radiation-sensitive acid generator (B) and a cation that does not contain a halogen-free electron-withdrawing group, which is obtained by removing the halogen-free electron-withdrawing group from the cation represented by formula (1) or (2). That is, a cation in which p1, p2, and p3 are each independently an integer of 0 to 3 and p1+p2+p3 is 0 or greater in formula (1), and a cation in which p4 and p5 are each independently an integer of 0 to 3 and p4+p5 is 0 or greater in formula (2) can be suitably used.
• the third onium cation is preferably an onium cation represented by the above formula (1) or (2).
• the third onium cation include the following.
• the fluorine atom, iodine atom, and fluorine atom-containing group in the onium cations below may be substituted with a hydrogen atom or other substituents.
• the iodonium cation of U + can be, for example, a diaryliodonium cation having one or more fluorine atoms.
• the acid diffusion control agent (D) can be synthesized by a known method, particularly a salt exchange reaction.
• Other known acid diffusion control agents can also be used as long as they do not impair the effects of the present invention.
• the acid diffusion controllers (D) may be used alone or in combination of two or more kinds.
• the lower limit of the content of the acid diffusion controller (total amount when multiple types are used) is preferably 15 mol %, more preferably 20 mol %, and even more preferably 25 mol %, based on the radiation-sensitive acid generator (B) or the radiation-sensitive acid-generating polymer (A1) (based on the total amount when both are included).
• the upper limit of the content is preferably 100 mol %, more preferably 90 mol %, and even more preferably 80 mol %. This allows excellent sensitivity and CDU to be exhibited when forming a resist pattern.
• the radiation-sensitive composition of the present embodiment may contain, as another polymer, a polymer having a higher mass content of fluorine atoms than the base polymer (hereinafter, also referred to as a "high fluorine content polymer").
• a polymer having a higher mass content of fluorine atoms than the base polymer hereinafter, also referred to as a "high fluorine content polymer”
• the high fluorine content polymer can be unevenly distributed in the surface layer of the resist film relative to the base polymer, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.
• the high fluorine content polymer preferably has a structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit (V)").
• structural unit (V) structural unit
• the high fluorine content polymer may have at least one of the structural units (I) to (III) in the base polymer as necessary.
• R 73 is a hydrogen atom, a methyl group or a trifluoromethyl group.
• G L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO 2 ONH-, -CONH- or -OCONH-.
• R 74 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.
• R 73 is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
• G L is preferably a single bond or --COO--, and more preferably --COO--.
• Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by R74 include linear or branched alkyl groups having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.
• Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R74 include monocyclic or polycyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.
• R 74 is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and further preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a 5,5,5-trifluoro-1,1-diethylpentyl group, or a 1,1,1,2,2,3,3-heptafluoro-6-methylheptan-4-yl group.
• the lower limit of the content of the structural unit (V) is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%, based on all structural units constituting the high fluorine content polymer.
• the upper limit of the content is preferably 100 mol%, more preferably 95 mol%, and even more preferably 90 mol%.
• the lower limit of the Mw of the high fluorine content polymer is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 5,000.
• the upper limit of the Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, and particularly preferably 15,000.
• the Mw/Mn of the high fluorine content polymer is usually 1 or more, and more preferably 1.1 or more.
• the above Mw/Mn is usually 5 or less, and is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.2 or less.
• the lower limit of the content of the high fluorine content polymer is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass, relative to 100 parts by mass of the polymer (A).
• the upper limit of the content is preferably 10 parts by mass, more preferably 8 parts by mass, and even more preferably 5 parts by mass.
• the high fluorine content polymer can be synthesized by a method similar to that for synthesizing the base polymer described above.
• the radiation-sensitive composition according to this embodiment contains a solvent (C).
• the solvent (C) is not particularly limited as long as it is a solvent capable of dissolving or dispersing the polymer (A) and additives, etc., which are optionally contained therein.
• Examples of the solvent (C) include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.
• Alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, diacetone alcohol, and methyl 2-hydroxyisobutyrate; Polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples of the polyhydric alcohol partially etherified solvents include those obtained by etherifying some of the hydroxy groups of the above-mentioned polyhydric alcohol solvents.
• the alcohol-based solvents also include alcohol acid ester-based solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, i-propyl 2-hydroxyisobutyrate, i-butyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate.
• alcohol acid ester-based solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, i-propyl 2-hydroxyisobutyrate, i-butyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate.
• ether solvents include: Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents, such as diphenyl ether and anisole (methyl phenyl ether);
• the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.
• ketone solvent examples include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, methylcyclohexanone, etc.: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.
• amide solvent examples include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone;
• solvent examples include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.
• ester-based solvents include: Monocarboxylate solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate solvents, such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as ⁇ -butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate;
• the solvent include polyvalent carboxylate diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.
• hydrocarbon solvent examples include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane;
• solvent examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.
• ester-based solvents, ketone-based solvents, alcohol-based solvents, and ether-based solvents are preferred, with polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents, lactone-based solvents, alcohol acid ester-based solvents, polyhydric alcohol partial ether-based solvents, and monocarboxylic acid ester-based solvents being more preferred, and with propylene glycol monomethyl ether acetate, cyclohexanone, ⁇ -butyrolactone, propylene glycol monomethyl ether, diacetone alcohol, ethyl lactate, and methyl 2-hydroxy-2-methylpropionate being even more preferred.
• the radiation-sensitive composition may contain one or more types of solvents.
• the radiation-sensitive composition may contain other optional components in addition to the above components.
• the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, etc. These other optional components may be used alone or in combination of two or more.
• the radiation-sensitive composition can be prepared, for example, by mixing the polymer (A) and the solvent (C) with other optional components, if necessary, in a predetermined ratio. After mixing, the radiation-sensitive composition is preferably filtered, for example, through a filter having a pore size of about 0.05 ⁇ m to 0.4 ⁇ m.
• the solid content concentration of the radiation-sensitive composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.
• the pattern forming method in this embodiment includes the steps of: A step (1) of directly or indirectly applying the radiation-sensitive composition to a substrate to form a resist film (hereinafter also referred to as a "resist film forming step”); A step (2) of exposing the resist film to light (hereinafter also referred to as an "exposure step”); and The method includes a step (3) of developing the exposed resist film with a developer (hereinafter, also referred to as the "developing step”).
• the pattern formation method described above uses the radiation-sensitive composition, which can form a resist film with excellent sensitivity, CDU, and development defect suppression, and therefore can form a high-quality resist pattern. Each step is described below.
• a resist film is formed from the radiation-sensitive composition.
• the substrate on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers.
• an organic or inorganic anti-reflective film disclosed in, for example, JP-B-6-12452 and JP-A-59-93448 may be formed on the substrate.
• the coating method include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film.
• the PB temperature is usually 60° C. to 160° C., and preferably 80° C. to 140° C.
• the PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.
• the thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.
• the exposure step is carried out with radiation having a wavelength of 50 nm or less
• the resist film formed in the resist film forming step (1) above is irradiated with radiation through a photomask (or, in some cases, through an immersion medium such as water) to expose the resist film.
• radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern.
• far ultraviolet light, electron beams, and EUV are preferred
• ArF excimer laser light wavelength 193 nm
• KrF excimer laser light wavelength 248 nm
• electron beams, and EUV are more preferred
• PEB post-exposure bake
• This PEB creates a difference in solubility in the developer between the exposed and unexposed parts.
• the PEB temperature is usually 50°C to 180°C, with 80°C to 150°C being preferred.
• the PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.
• step (3) above the resist film exposed in the exposure step (2) above is developed with a developer. This allows a desired resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.
• a rinse liquid such as water or alcohol
• examples of the developer used in the above development include an alkaline aqueous solution in which at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved.
• TMAH tetramethylammonium hydroxide
• TMAH tetramethylammonium hydroxide
• TMAH 1,8-diazabicyclo-[5.4.0]-7-undecene
• examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, or solvents containing organic solvents.
• examples of the organic solvent include one or more of the solvents listed as the solvents for the radiation-sensitive composition described above.
• ester solvents and ketone solvents are preferred.
• As the ester solvent acetate solvents are preferred, and n-butyl acetate and amyl acetate are more preferred.
• As the ketone solvent chain ketones are preferred, and 2-heptanone is more preferred.
• the content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more.
• components other than the organic solvent in the developer include water and silicone oil.
• Development methods include, for example, a method in which the substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the substrate surface by surface tension and left to stand for a certain period of time (paddle method), a method in which developer is sprayed onto the substrate surface (spray method), and a method in which developer is continuously dispensed while scanning a developer dispense nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method).
• dip method a method in which the substrate is immersed in a tank filled with developer for a certain period of time
• paddle method a method in which developer is piled up on the substrate surface by surface tension and left to stand for a certain period of time
• spray method a method in which developer is sprayed onto the substrate surface
• dynamic dispense method a method in which developer is continuously dispensed while scanning a developer dispense nozzle at a constant speed onto a substrate rotating at
• the radiation-sensitive acid generator in this embodiment is an onium cation containing an electron-withdrawing group that does not contain a halogen atom; and a sulfonate anion containing an iodine atom.
• the radiation-sensitive acid generator may be the same as the radiation-sensitive acid generator (B) described above.
• Mw and Mn The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using GPC columns (two "G2000HXL”, one "G3000HXL”, and one "G4000HXL") manufactured by Tosoh Corporation under the following conditions.
• Eluent Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
• Flow rate 1.0 mL/min
• Sample concentration 1.0 mass%
• Sample injection volume 100 ⁇ L
• Base polymers (A-1) to (A-15) were synthesized as polymer (A) according to the following method.
• Compounds represented by the following formulas (M-1) to (M-16) (hereinafter also referred to as “monomers (M-1) to (M-16)") were used in the synthesis of polymer (A).
• “parts by mass” means a value when the total mass of the monomers used is taken as 100 parts by mass
• mol % means a value when the total number of moles of the monomers used is taken as 100 mol %.
• Polymer (A) As the polymer (A), the base polymers (A-1) to (A-15) synthesized in the above Synthesis Examples A-1 to A-15 were used.
• Acid Diffusion Controller (D) As the acid diffusion controller (D), compounds represented by the following formulae (D-1) to (D-6) were used.
• R-1 100 parts by mass of (A-1) as a base polymer (A), 60 parts by mass of (B-1) as a radiation-sensitive acid generator (B), 70 mol % of (D-1) as an acid diffusion controller (D) relative to (B-1), 5,500 parts by mass of (C-1) as a solvent (C), and 1,500 parts by mass of (C-2) were mixed.
• the resulting mixture was filtered through a filter having a pore size of 0.2 ⁇ m to prepare a radiation-sensitive composition (R-1).
• a composition for forming a lower anti-reflective coating (“ARC66” by Brewer Science) was applied onto a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" by Tokyo Electron Co., Ltd.), and then heated at 205° C. for 60 seconds to form a lower anti-reflective coating having an average thickness of 105 nm.
• Each radiation-sensitive composition shown in Table 2 was applied onto this lower anti-reflective coating using the spin coater, and post-baked (PB) was performed at 130° C. for 60 seconds. Thereafter, the coating was cooled at 23° C. for 30 seconds to form a resist film having an average thickness of 45 nm.
• This resist film was exposed using an EUV scanner ("NXE3300" by ASML (NA 0.33, ⁇ 0.9/0.6, quadrupole illumination, hole pattern mask with a pitch of 50 nm on the wafer and a +20% bias).
• PEB was performed for 60 seconds on a hot plate at 100°C, and development was performed for 30 seconds with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution to form a resist pattern with 25 nm holes and 50 nm pitch (hereinafter also referred to as "25 nm contact hole pattern").
• TMAH tetramethylammonium hydroxide
• the exposure amount for forming the 25 nm contact hole pattern was determined as the optimum exposure amount, and this optimum exposure amount was determined as the sensitivity (mJ/ cm2 ). The smaller the value of the sensitivity, the better it is.
• the sensitivity was evaluated as "A” (very good) when it was less than 60 mJ/ cm2 , "B” (good) when it was 60 mJ/ cm2 or more and 63 mJ/cm2 or less , and "C” (bad) when it exceeded 63 mJ/ cm2 .
• CDU was evaluated as "A” (very good) when it was less than 3.3 nm, "B” (good) when it was 3.3 nm or more and less than 3.6 nm, and "C” (bad) when it was 3.6 nm or more.
• the resist film was exposed to an optimal exposure dose and developed to form a 25 nm contact hole pattern.
• the number of defects on the wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Among the defects measured, defects with a diameter of 0.5 ⁇ m or less were judged to be originating from the resist film.
• the number of developed defects was judged as "A" (very good) when the number of defects judged to be originating from the resist film was less than 30, "B" (good) when the number was 30 to 50, and "C” (bad) when the number was more than 50.
• the radiation-sensitive compositions of the examples had good sensitivity and CDU, and also had a small number of development defects.
• the radiation-sensitive composition and the method for forming a resist pattern described above a resist pattern having good sensitivity to exposure light, excellent CDU, and few development defects can be formed. Therefore, these compositions can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

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