Classifications

• • 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
• • 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 and a pattern forming method.
• 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 polymer 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 improvements in the performance of resist materials used for exposure to such radiation are being considered (JP Patent Publication No. 2020-075910).
• next-generation technologies also require resist performance that is equal to or better than conventional performance in terms of sensitivity, critical dimension uniformity (CDU) performance, which is an index of uniformity of line width and hole diameter, and LWR (Line Width Roughness) performance, which indicates the variation in line width and resist pattern line width.
• CDU critical dimension uniformity
• LWR Line Width Roughness
• the present invention aims to provide a radiation-sensitive composition and pattern formation method that can provide sufficient levels of sensitivity, CDU performance, and LWR performance when forming a resist pattern using next-generation technology.
• the present invention comprises: A polymer including a structural unit having an acid dissociable group; a radiation-sensitive acid generator including a first organic acid anion and a first onium cation; an acid diffusion controller that includes a second organic acid anion and a second onium cation and that generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon exposure to radiation;
• a solvent and the first organic acid anion includes an acid anion portion and an aromatic ring having at least both a first substituent and a second substituent, the first substituent and the second substituent each independently being a hydroxy group, a sulfo group, or a sulfanyl group;
• the present invention relates to a radiation-sensitive composition, wherein at least one selected from the group consisting of the polymer, the radiation-sensitive acid generator, and the acid diffusion controller contains an iodine group.
• the radiation-sensitive composition can exhibit excellent sensitivity, CDU performance, and LWR performance during resist pattern formation. Although the reason is unclear, it is presumed as follows.
• At least one selected from the group consisting of a polymer, a radiation-sensitive acid generator, and an acid diffusion control agent contains an iodine group.
• the iodine group iodine atom
• EUV extreme ultraviolet
• the use of an iodine group may increase the hydrophobicity of the radiation-sensitive composition and reduce its solubility in a developer.
• the first organic acid anion contains an acid anion portion and an aromatic ring having at least both a first substituent and a second substituent, and the first substituent and the second substituent are each independently a hydroxyl group, a sulfo group, or a sulfanyl group.
• the first and second substituents with high polarity of the radiation-sensitive acid generator interact with the polar portion of the polymer component (for example, by hydrogen bonding, etc.), increasing the glass transition temperature of both as a whole.
• This allows the acid generated from the radiation-sensitive acid generator to have an appropriately short diffusion length, thereby improving the CDU and LWR performance. It is presumed that the above-mentioned resist performance can be exhibited by these combined actions.
• the present invention comprises: 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.
• This pattern formation method uses the above-mentioned radiation-sensitive composition, which is capable of exhibiting excellent sensitivity, CDU performance, and LWR performance when forming a resist pattern, so that a high-quality resist pattern can be efficiently formed.
• the radiation-sensitive composition according to this embodiment (hereinafter, also simply referred to as the "composition”) comprises a polymer (hereinafter, also referred to as the "base polymer”), a radiation-sensitive acid generator, and an acid diffusion controller.
• the composition further comprises a solvent.
• the composition may contain other optional components as long as the effects of the present invention are not impaired.
• At least one selected from the group consisting of the polymer, the radiation-sensitive acid generator, and the acid diffusion controller contains an iodine group. This allows the obtained resist film to have a high sensitivity.
• the manner in which the iodine group is contained is not particularly limited, it is preferable that the iodine group is contained in the form of an iodine group-containing aromatic ring structure.
• the iodine group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms in the aromatic ring are substituted with iodine groups.
• at least one selected from the group consisting of the acid-dissociable group, the first organic acid anion, and the second organic acid anion contains an iodine group-containing aromatic ring structure.
• the aromatic ring in the iodo group-containing aromatic ring structure is not particularly limited as long as it is a ring structure having aromaticity.
• the aromatic ring 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 tria
• the number of iodine groups in the iodine group-containing aromatic ring structure is not particularly limited, but is preferably 1 to 4, and more preferably 1, 2 or 3.
• the polymer i.e., base polymer
• the polymer is an assembly of polymer chains containing a structural unit having an acid-dissociable group (hereinafter also referred to as "structural unit (I)").
• the base polymer may contain a structural unit (II) having a phenolic hydroxyl group or a structural unit (III) containing a lactone structure.
• the composition may contain one or more types of base polymers. Each structural unit will be described below.
• 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 has 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.
• the acid dissociable group contains the above-mentioned iodine group-containing aromatic ring structure.
• a structural unit represented by the following formula (3) hereinafter also referred to as "structural unit (I-1)
• structural unit (I-1) is preferable.
• R 17 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
• R 18 is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms.
• R 19 and R 20 are each independently a monovalent substituted or unsubstituted chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent substituted or unsubstituted 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.
• L 11 represents * -COO- or * -L 11a COO-.
• L 11a is a substituted or unsubstituted arenediyl group. * is a bond to the carbon atom to which R 17 is bonded.
• R 17 is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
• Examples of the arenediyl group represented by L 11a include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a benzenediyl group and a naphthalenediyl group.
• L 11a is preferably a benzenediyl group.
• Examples of the substituent that the arenediyl group represented by L11a may have include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, and an alkoxy group.
• a halogen atom a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.
• Examples of the alkyl group as the substituent of L 11a include linear or branched alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, and a propyl group.
• Examples of the fluorinated alkyl group include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms, such as a trifluoromethyl group and a pentafluoroethyl group.
• Examples of the alkoxycarbonyloxy group include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as a methoxycarbonyloxy group, a butoxycarbonyloxy group, and an adamantylmethyloxycarbonyloxy group.
• acyl group examples include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as an acetyl group, a propionyl group, a benzoyl group, and an acryloyl group.
• acyloxy group examples include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as an acetyloxy group, a propionyloxy group, a benzoyloxy group, and an acryloyloxy group.
• alkoxy group examples include linear or branched alkoxy groups having 1 to 8 carbon atoms, such as a methoxy group, an ethoxy group, and a propoxy group.
• Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 18 include a monovalent 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 monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, iso-butyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.
• Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups; polycyclic alicyclic saturated hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups; monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl and cyclohexenyl groups; and polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl groups.
• Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.
• R 18 is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.
• Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R 19 and R 20 include groups corresponding to those having 1 to 10 carbon atoms among the monovalent chain hydrocarbon groups having 1 to 20 carbon atoms in R 18 above.
• Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R 19 and R 20 include the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms for R 18 above.
• the divalent alicyclic group having 3 to 20 carbon atoms constituted by combining R 19 and R 20 together with the carbon atom to which they are bonded is not particularly limited as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group.
• preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups
• preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups.
• Preferred polycyclic alicyclic hydrocarbon groups include bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1 3,7 ]decane-2,2-diyl (adamantane-2,2-diyl).
• R 18 is an alkyl group, an alkenyl group, or a phenyl group having 1 to 4 carbon atoms, and that the alicyclic structure formed by combining R 19 and R 20 together with the carbon atom to which they are bonded is a polycyclic or monocyclic cycloalkane structure.
• substituents which R 18 to R 20 may have, the substituents which the arenediyl group represented by L 11a may be suitably employed.
• structural unit (I-1) examples include structural units represented by the following formulas (3-1) to (3-12) (hereinafter also referred to as “structural units (I-1-1) to (I-1-12)").
• R 17 to R 20 have the same meaning as in the above formula (3).
• R L11 is a halogen atom, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an alkoxy group.
• i and j are each independently an integer of 1 to 4.
• k and l are each 0 or 1.
• 3a is each independently an integer of 0 to 3. When 3a is 2 or more, multiple R L11 are the same or different from each other.
• R 18 is preferably a methyl group, an ethyl group, an isopropyl group, an ethenyl group, a phenyl group, or an iodophenyl group.
• R 19 and R 20 are preferably a methyl group, an ethyl group, or an isopropyl group.
• R L11 is preferably an iodine atom or an alkoxy group.
• polymer may contain structural units represented by the following formulas (1f) to (2f) as structural unit (I).
• R ⁇ f is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
• R ⁇ f is independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms.
• h 1 is an integer of 1 to 4.
• R ⁇ f is preferably a hydrogen atom, a methyl group or an ethyl group.
• the lower limit of the content of the structural unit (I) (the total content when multiple types of structural unit (I) are present) is preferably 20 mol%, more preferably 25 mol%, and even more preferably 30 mol% relative to all structural units constituting the base polymer.
• the upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%.
• the structural unit (II) is a structural unit having a phenolic hydroxyl group.
• the polymer contains the structural unit (II), so that the solubility in the developer can be adjusted more appropriately, and as a result, the sensitivity of the radiation-sensitive composition can be further improved.
• the structural unit (II) contributes to improving the etching resistance and improving the difference in developer solubility (dissolution contrast) between the exposed and unexposed parts.
• it can be suitably applied to pattern formation using exposure to radiation having a wavelength of 50 nm or less, such as electron beam or EUV.
• the structural unit (II) is preferably represented by the following formula (2).
• R ⁇ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
• L CA is a single bond, —COO— * or —O—. * is a bond on the aromatic ring side.
• R 102 is a halogen atom, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group or an acyloxy group. When a plurality of R 102 are present, the plurality of R 102 are the same or different from each other.
• n3 is an integer from 0 to 2
• m3 is an integer from 1 to 8
• m4 is an integer from 0 to 8, provided that 1 ⁇ m3 + m4 ⁇ 2n3 +5 is satisfied.
• R ⁇ is preferably a hydrogen atom or a methyl group.
• L CA is preferably a single bond or --COO-- * .
• halogen atom alkyl group, fluorinated alkyl group, alkoxycarbonyloxy group, acyl group or acyloxy group in R 102
• the groups exemplified as the substituent of L 11a in the above formula (3) can be suitably adopted.
• the halogen atom in R 102 an iodine atom is preferable.
• n3 is more preferably 0 or 1, and further preferably 0.
• m3 is preferably an integer of 1 to 3, and more preferably 1 or 2.
• m4 is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.
• the structural unit (II) is preferably one of the structural units represented by the following formulas (2-1) to (2-20) (hereinafter also referred to as “structural unit (2-1) to structural unit (2-20)").
• R ⁇ is the same as in the above formula (2).
• the lower limit of the content of the structural unit (II) (total when multiple types of structural unit (II) are present) is preferably 15 mol%, more preferably 25 mol%, and even more preferably 35 mol%, based on all structural units constituting the base polymer.
• the upper limit of the above content is preferably 85 mol%, more preferably 75 mol%, and even more preferably 70 mol%.
• a monomer having a phenolic hydroxyl group such as hydroxystyrene
• a protecting group such as an alkali-dissociable group (e.g., an acyl group)
• the phenolic hydroxyl group of hydroxystyrene may also be polymerized without being protected.
• the structural unit (III) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.
• the base polymer further contains the structural unit (III), which allows the base polymer to adjust its solubility in a developer, and as a result, the radiation-sensitive composition can improve lithography performance such as resolution. In addition, the adhesion between a resist pattern formed from the base polymer and a substrate can be improved.
• Examples of the structural unit (III) include structural units represented by the following formulas (T-1) to (T-11).
• R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
• R L2 to R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group.
• R L4 and R L5 may be combined with each other to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atom to which they are bonded.
• L 2 is a single bond or a divalent linking group.
• X is an oxygen atom or a methylene group.
• k is an integer of 0 to 3.
• m is an integer of 1 to 3.
• divalent alicyclic group having 3 to 8 carbon atoms constituted by R L4 and R L5 taken together with the carbon atom to which they are bonded a group corresponding to the structure having 3 to 8 carbon atoms among the divalent alicyclic groups having 3 to 20 carbon atoms constituted by R 19 and R 20 in the above formula (3) taken together with the carbon atom to which they are bonded can be suitably used.
• One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.
• Examples of the divalent linking group represented by L2 above include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from the group consisting of -CO-, -O-, -NH-, and -S-.
• the structural unit (III) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.
• the lower limit of the content of the structural unit (III) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on the total structural units constituting the base polymer.
• the upper limit of the above content is preferably 40 mol%, more preferably 35 mol%, and even more preferably 30 mol% or less.
• the base polymer may optionally have other structural units.
• the other structural units include structural units (IV) containing polar groups (excluding those corresponding to structural units (III)).
• the base polymer may further have structural units (IV) to adjust the solubility in a developer, thereby improving the lithography performance such as the resolution of the radiation-sensitive composition.
• the polar groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and sulfonamide groups. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.
• Examples of the structural unit (IV) include structural units represented by the following formula:
• R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
• the lower limit of the content of the structural unit (IV) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on the total structural units constituting the base polymer.
• the upper limit of the content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.
• the base polymer may contain a structural unit (VII) having a third organic acid anion and a third onium cation, and including a first acid generating structure that generates an acid that dissociates the acid dissociable group upon exposure to light.
• the onium salt structure i.e., the first acid generating structure
• the onium salt structure formed by the third organic acid anion and the third onium cation functions as a radiation-sensitive acid generating structure.
• the base polymer contains the above-mentioned radiation-sensitive acid generating structure
• the polarity of the base polymer in the exposed area increases, making it soluble in the developer when developed with an alkaline aqueous solution, but insoluble in the developer when developed with an organic solvent.
• the form of the third organic acid anion and the third onium cation in the structural unit (VII) of the base polymer is not particularly limited, and the base polymer may have the third organic acid anion as a side chain portion, or may have the third onium cation as a side chain portion. Having the third organic acid anion or the third onium cation as a side chain portion means that the corresponding third organic acid anion or the third onium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.
• the third organic acid anion is bonded to the main chain as a side chain structure of the base polymer
• the third onium cation is ionically bonded to the third organic acid anion as a counter ion of the third organic acid anion.
• the third organic acid anion is ionically bonded to the third onium cation as a counter ion of the third onium cation.
• the base polymer has the third organic acid anion as a side chain portion.
• the third organic acid anion preferably has at least one anion selected from the group consisting of sulfonate anion and sulfonimide anion as the acid anion portion.
• the acid generated by exposure include sulfonic acid and sulfonimide, which correspond to the acid anion portion.
• the third organic acid anion preferably contains, as a structure other than the acid anion portion, -O-, -CO-, a cyclic structure, or a combination thereof.
• the combination also includes a structure in which -O- or -CO- is incorporated as a portion that forms a ring in the cyclic structure (heterocyclic structure).
• the third organic acid anion preferably has a sulfonate anion as the acid anion portion, and an electron-withdrawing group is bonded to the carbon atom at the ⁇ -position or ⁇ -position relative to the sulfur atom in the sulfonate anion.
• the electron-withdrawing group include a fluorine atom, a fluorinated hydrocarbon group, a nitro group, and a cyano group.
• the fluorinated hydrocarbon group a perfluoroalkyl group having 1 to 5 carbon atoms is preferable.
• the third organic acid anion preferably has an iodine group.
• the third organic acid anion preferably contains the iodine group-containing aromatic ring structure as the form in which the iodine group is contained.
• the third onium cation may be a radioactively decomposable onium cation.
• the radioactively decomposable onium cation include a sulfonium cation, a tetrahydrothiophenium cation, and an iodonium cation. Among these, a sulfonium cation or an iodonium cation is preferred, and a sulfonium cation is more preferred.
• the third onium cation preferably has a fluoro group or an iodine group.
• the third onium cation preferably has a fluoro group-containing aromatic ring structure as a form of containing a fluoro group.
• the fluoro group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms in an aromatic ring are substituted with fluoro groups.
• an aromatic ring in an iodine group-containing aromatic ring structure can be suitably adopted.
• the third onium cation preferably includes the iodine group-containing aromatic ring structure as a form of containing an iodine group.
• the structural unit (VII) can efficiently exert the above-mentioned functions by combining the above structures.
• the structural unit (VII) is preferably a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (VII-1)").
• R V is a hydrogen atom or a methyl group.
• V 1 is a single bond or an ester group.
• V 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, or an amide bond, and a part of the methylene groups constituting the alkylene group, the cycloalkylene group or the arylene group may be substituted with an ether group, an ester group or a lactone ring-containing group.
• V 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 groups constituting the alkylene group may be substituted with an ether group or an ester group.
• Some or all of the hydrogen atoms in V2 and V3 may be substituted with a heteroatom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.
• Rf1a to Rf4a each independently represent a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a fluorinated hydrocarbon group.
• Z1 + represents a sulfonium cation or an iodonium cation.
• the monovalent hydrocarbon group having 1 to 20 carbon atoms in V2 and V3 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 unit (IV-1) is preferably a structural unit represented by the following formula (a1-1):
• R V , Rf 1a to Rf 4a , V 1 and Z 1 + 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.
• ma is an integer of 0 to 4.
• na is an integer of 0 to 3.
• Examples of the third organic acid anion of the monomer that gives the structural unit (VII) include, but are not limited to, those shown below.
• the iodo group of the iodo group-containing aromatic ring structure may be substituted with a hydrogen atom or the substituent shown in L11 of the above formula (3).
• R and V have the same meanings as above.
• a third onium cation is bonded to the main chain as a side chain structure of the base polymer, and a third organic acid anion is ionically bonded to the third onium cation as a counter ion of the third onium cation.
• the third onium cation is bonded to the main chain via a divalent linking group or a single bond, and the structure from V2 to SO3- in the above formula (a1 ) is ionically bonded to the third onium cation as a counter ion.
• the divalent linking group a group represented by L11 in the above formula (3) can be suitably adopted.
• the lower limit of the content of structural unit (VII) (the total content when multiple types are included) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% based on all structural units constituting the base polymer.
• the upper limit of the above content is preferably 40 mol%, more preferably 30 mol% or less, and even more preferably 25 mol% or less.
• the monomer that gives the structural unit (VII-1) can be synthesized, for example, in a manner similar to that of the sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363.
• the base polymer may contain a structural unit (VIII) having a fourth organic acid anion and a fourth onium cation, and including a second acid generating structure that generates an acid that does not dissociate the acid dissociable group upon exposure.
• the onium salt structure i.e., the second acid generating structure formed by the fourth organic acid anion and the fourth onium cation functions as an acid diffusion control structure.
• the second acid generating structure does not substantially dissociate the acid dissociable group of the structural unit (I) under the pattern formation conditions using the radiation-sensitive composition, and has a function of suppressing the diffusion of the acid generated from the first acid generating structure or the radiation-sensitive acid generator in the unexposed area by salt exchange.
• the acid generated from the second acid generating structure is a relatively weaker acid (acid with a higher pKa) than the acid generated from the first acid generating structure.
• the onium salt structure functions as a radiation-sensitive acid generating structure or an acid diffusion control structure is determined by the energy required to dissociate the acid dissociable group of the base polymer, and the acidity of the onium salt structure or the generated acid.
• the form of inclusion of the fourth organic acid anion and the fourth onium cation in the structural unit (VIII) of the base polymer is not particularly limited, and the base polymer may have the fourth organic acid anion as a side chain portion, or may have the fourth onium cation as a side chain portion. Having as a side chain portion means that the corresponding fourth organic acid anion or fourth onium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.
• the fourth onium cation is ionically bonded to the fourth organic acid anion as a counter ion of the fourth organic acid anion.
• the fourth organic acid anion is ionically bonded to the fourth onium cation as a counter ion of the fourth onium cation.
• the base polymer has the fourth organic acid anion as a side chain portion.
• the fourth organic acid anion preferably has a sulfonate anion or a carboxylate anion as the acid anion portion, and more preferably has a carboxylate anion.
• the fourth organic acid anion has the sulfonate anion
• no electron-withdrawing group is bonded to the carbon atom at the ⁇ -position or ⁇ -position relative to the sulfur atom in the sulfonate anion.
• the electron-withdrawing group include the electron-withdrawing group that the third organic acid anion may have in the first acid generating structure.
• the acid generated by exposure is a carboxylic acid or sulfonic acid corresponding to the acid anion portion.
• the fourth organic acid anion preferably contains, as a structure other than the acid anion portion, -O-, -CO-, a cyclic structure, or a combination thereof.
• the structure shown for the third organic acid anion can be suitably adopted.
• the fourth organic acid anion preferably has an iodine group or a hydroxyl group.
• the fourth organic acid anion preferably contains the iodine group-containing aromatic ring structure as the form in which the iodine group is contained.
• the fourth onium cation may be, for example, a radiolytic or non-radiolytic onium cation.
• the radiolytic or non-radiolytic onium cation may be, for example, a sulfonium cation, a tetrahydrothiophenium cation, an iodonium cation, an ammonium cation, or the like.
• a sulfonium cation or an iodonium cation is preferred, and a sulfonium cation is more preferred.
• the fourth onium cation preferably has a fluoro group or an iodine group.
• the fourth onium cation preferably contains the fluoro group-containing aromatic ring structure or the iodine group-containing aromatic ring structure as a form of containing the fluoro group or the iodine group.
• the structural unit (VIII) can efficiently exert the above-mentioned functions by combining the above structures.
• the structural unit (VIII) is preferably a structural unit represented by the following formula (p1) (hereinafter also referred to as “structural unit (VIII-1)").
• R 1 P is a hydrogen atom or a methyl group.
• X 1 represents a single bond, an ester bond, an ether bond, a phenylene group, or a naphthylene group.
• X2 is a single bond, a saturated hydrocarbylene group having 1 to 12 carbon atoms, or a phenylene group, and the saturated hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a lactone ring, or a sultone ring.
• the hydrocarbylene group represented by X2 may be linear, branched, or cyclic, and specific examples thereof include a methylene group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a butane-2,2-diyl group, a butane-2,3-diyl group, a 2-methylpropane-1,3 alkanediyl groups having 1 to 12 carbon atoms, such as 1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,
• X 3 is a single bond, an ester bond or an ether bond.
• R X is a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms, a halogen atom, a hydroxyl 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.
• Z 2 + has the same meaning as Z 1a + in formula (a1) above.
• y1 is an integer of 0 to 3.
• x1 is 2 or more, multiple R 1 X's are the same or different.
• y2 is 0 or 1.
• Examples of the fourth organic acid anion of the monomer that gives the structural unit (VIII) include, but are not limited to, those shown below.
• the iodine group or hydroxy group in the following formula may be substituted with a hydrogen atom or the substituent shown in L 11 of the above formula (3).
• R P is the same as above.
• the fourth organic acid anion preferably has a carboxylate anion and a hydroxyl group.
• the carboxylate anion and the hydroxyl group are bonded to the same aromatic ring in the fourth organic acid anion, and it is more preferable that the carbon atom to which the carboxylate anion is bonded and the carbon atom to which the hydroxyl group is bonded are directly bonded to each other in the same aromatic ring.
• a quaternary onium cation is bonded to the main chain as a side chain structure of the base polymer, and a quaternary organic acid anion is ionically bonded to the quaternary onium cation as a counter ion of the quaternary onium cation.
• the quaternary onium cation is bonded to the main chain via a divalent linking group or a single bond, and the structure from X1 to COO- in the above formula (p1) is ionically bonded to the quaternary onium cation as a counter ion.
• the divalent linking group a group represented by L11 in the above formula (3) can be suitably adopted.
• the lower limit of the content of structural unit (VIII) (total content when multiple types are contained) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% based on all structural units constituting the base polymer.
• the upper limit of the content is preferably 40 mol%, more preferably 30 mol% or less, and even more preferably 25 mol% or less.
• the total amount of the monomer that gives the structural unit (VIII) and the acid diffusion control agent may be within the above range. By setting the content of structural unit (VIII) within the above range, the function as an acid diffusion control structure can be fully exhibited.
• one polymer chain may contain the structural unit (VII) and the structural unit (VIII), or one polymer chain may contain the structural unit (VII) and another polymer chain may contain the structural unit (VIII). It is sufficient that the polymer chain assembly contains the structural unit (VII) and the structural unit (VIII).
• the base polymer can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator or the like.
• the radical polymerization initiator may be an azo radical initiator such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or dimethyl 2,2'-azobisisobutyrate; or a peroxide radical initiator such as benzoyl peroxide, t-butyl hydroperoxide, or cumene hydroperoxide.
• AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred.
• These radical initiators may be used alone or in combination of two or more.
• Examples of the solvent used in the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylates such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl
• the reaction temperature in the above polymerization is usually 40°C to 150°C, preferably 50°C to 120°C.
• the reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.
• the molecular weight of the base polymer is not particularly limited, but the lower limit of the polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably 2,000, more preferably 3,000, even more preferably 4,000, and particularly preferably 4,500.
• the upper limit of Mw is preferably 20,000, more preferably 10,000, even more preferably 8,000, and particularly preferably 7,000.
• the ratio of Mw to the polystyrene equivalent number average molecular weight (Mn) of the base polymer by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.
• the lower limit of the content of the base polymer is preferably 40% by mass, more preferably 50% by mass, and even more preferably 55% by mass, based on the total solid content of the radiation-sensitive composition.
• the upper limit of the content is preferably 80% by mass, more preferably 75% by mass, and even more preferably 70% by mass.
• the radiation-sensitive composition of the present embodiment may contain, as the other 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, it is possible to modify the surface of the resist film during EUV exposure and control the distribution of the composition within the film.
• the high fluorine content polymer preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as “structural unit (V)”), and may have structural unit (I) or structural unit (IV) in the above base polymer, as necessary.
• R 13 is a hydrogen atom, a methyl group or a trifluoromethyl group.
• G L is a single bond, an alkanediyl group having 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, -SO 2 ONH-, -CONH-, -OCONH- or a combination thereof.
• R 14 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 13 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 R 14 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 R 14 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 14 is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and further preferably a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropan-2-yl group, or a 5,5,5-trifluoro-1,1-diethylpentyl group.
• the lower limit of the content of the structural unit (V) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on the total structural units constituting the high fluorine content polymer.
• the upper limit of the content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.
• the high fluorine content polymer may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V).
• structural unit (f-2) hereinafter also referred to as structural unit (VI)
• the high fluorine content polymer has improved solubility in an alkaline developer, and the occurrence of development defects can be suppressed.
• the structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also simply referred to as "alkali dissociable group").
• R C is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
• R D is a single bond, an (s+1)-valent hydrocarbon group having 1 to 20 carbon atoms, a structure in which an oxygen atom, a sulfur atom, -NR dd -, a carbonyl group, -COO-, -OCO-, or -CONH- is bonded to the end of the hydrocarbon group on the R E side, or a structure in which some of the hydrogen atoms of the hydrocarbon group are substituted with an organic group having a hetero atom.
• R dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.
• s is an integer of 1 to 3.
• R F is a hydrogen atom
• a 1 is an oxygen atom, -COO-* or -SO 2 O-*. * indicates the site bonding to R F.
• W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group.
• a 1 is an oxygen atom
• W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which A 1 is bonded.
• R E is a single bond or a divalent organic group having 1 to 20 carbon atoms.
• R E s When s is 2 or 3, a plurality of R E s , W 1 s , A 1 s and R F s may be the same or different.
• the structural unit (VI) has an alkali-soluble group (x), it is possible to increase affinity for an alkaline developer and suppress development defects.
• a 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.
• RF is a monovalent organic group having 1 to 30 carbon atoms
• a 1 is an oxygen atom, -NR aa -, -COO-*, -OCO-* or -SO 2 O-*.
• R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * indicates the site bonding to RF .
• W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.
• R E is a single bond or a divalent organic group having 1 to 20 carbon atoms.
• W 1 or RF has a fluorine atom on the carbon atom bonding to A 1 or on the carbon atom adjacent thereto.
• a 1 is an oxygen atom
• W 1 and R E are single bonds
• R D is a structure in which a carbonyl group is bonded to the end of a hydrocarbon group having 1 to 20 carbon atoms on the R E side
• R F is an organic group having a fluorine atom.
• s is 2 or 3
• a plurality of R E s , W 1 s , A 1 s and R F s may be the same or different.
• the structural unit (VI) has an alkali dissociable group (y)
• the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step.
• the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed.
• a 1 is -COO-*, and R F or W 1 or both of them have a fluorine atom.
• R 3 C is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
• R 3 E is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and even more preferably a group having a norbornane lactone structure.
• the lower limit of the content of the structural unit (VI) is preferably 40 mol%, more preferably 50 mol%, and even more preferably 55 mol%, based on all structural units constituting the high fluorine content polymer.
• the upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%.
• the high fluorine content polymer may contain the structural unit (I) or the structural unit (IV) in the base polymer as a structural unit other than the structural units listed above.
• the structural unit (IV) is preferably a structure containing a fluorine atom.
• the content ratio of the structural unit (I) in the high fluorine content polymer can suitably be the content ratio described for the base polymer.
• the lower limit of the content of the structural unit (IV) in all structural units constituting the high fluorine content polymer is preferably 50 mol%, more preferably 60 mol%, and even more preferably 65 mol%.
• the upper limit of the content is preferably 99 mol%, more preferably 98 mol%, and even more preferably 95 mol%.
• the lower limit of the Mw of the high fluorine content polymer is preferably 2,000, more preferably 3,000, and even more preferably 4,000.
• the upper limit of the Mw is preferably 20,000, more preferably 10,000, and even more preferably 7,000.
• the lower limit of Mw/Mn of the high fluorine content polymer is usually 1, and more preferably 1.1.
• the upper limit of the above Mw/Mn is usually 5, and more preferably 3, and more preferably 2.
• the content of the high-fluorine content polymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the base polymer. Also, the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less.
• the radiation-sensitive composition may contain one or more types of high fluorine content polymers.
• the high fluorine content polymer can be synthesized by a method similar to that for synthesizing the base polymer described above.
• the radiation-sensitive acid generator contains a first organic acid anion and a first onium cation, forming an onium salt structure.
• the radiation-sensitive acid generator is a component that generates an acid upon exposure.
• the acid generated upon exposure has the function of dissociating an acid-dissociable group of the base polymer and generating a carboxyl group or the like.
• the radiation-sensitive acid generator may be contained in the radiation-sensitive composition in a form in which the onium salt structure exists as a compound by itself (isolated from the polymer), in which the onium salt structure is incorporated as a part of the polymer, or in both of these forms.
• the radiation-sensitive acid generator may be contained in the radiation-sensitive composition in a form in which the onium salt structure exists as a compound by itself (low molecular weight).
• dissociation of an acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.
• the radiation-sensitive composition contains a radiation-sensitive acid generator
• the polarity of the polymer in the exposed area increases, making it soluble in the developer when developed with an alkaline aqueous solution, but insoluble in the developer when developed with an organic solvent.
• the first organic acid anion includes an acid anion portion and an aromatic ring having at least both a first substituent and a second substituent (hereinafter, the aromatic ring that is the parent skeleton is also referred to as a "specific aromatic ring").
• the first substituent and the second substituent are each independently a hydroxy group, a sulfo group, or a sulfanyl group.
• the acid anion portion is preferably a sulfonate anion or a sulfonimide anion, and more preferably a sulfonate anion.
• an aromatic ring in the above-mentioned iodine group-containing aromatic ring structure can be suitably used.
• the specific aromatic ring may be polycyclic or monocyclic, but is preferably a monocyclic ring, and more preferably a benzene ring.
• the number of specific aromatic rings in the radiation-sensitive acid generator is not particularly limited, but from the viewpoint of solubility, one, two or three are preferred, and one or two are more preferred.
• At least one of the first and second substituents is preferably a hydroxy group. It is more preferable that both the first and second substituents are hydroxy groups in terms of solubility in a developer, CDU performance, and LWR performance.
• first and second substituents in the specific aromatic ring are not specified, it is preferable that the first and second substituents are present in the ortho position (the carbon atom to which the first and second substituents are bonded are adjacent to each other). This forms an intramolecular hydrogen bond, relatively increasing the acidity, increasing the solubility of the radiation-sensitive acid generator, and inducing an increase in the glass transition temperature due to interaction with the polymer, resulting in improved CDU and LWR performance due to short diffusion.
• the specific aromatic ring may have one or more other substituents other than the first and second substituents.
• the other substituents include halogen atoms, carboxy groups, cyano groups, nitro groups, alkyl groups, fluorinated alkyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and alkoxy groups.
• the substituents that the arenediyl group represented by L 11a in the above formula (3) may have can be suitably adopted.
• the first organic acid anion preferably contains the iodine group-containing aromatic ring structure.
• the specific aromatic ring may have an iodine atom as a substituent other than the first substituent and the second substituent, forming the iodine group-containing aromatic ring structure.
• the first organic acid anion may contain the iodine group-containing aromatic ring structure in addition to the specific aromatic ring.
• the first organic acid anion preferably contains -O-, -CO-, a cyclic structure, or a combination thereof.
• the combination also includes a structure in which -O- or -CO- is incorporated as a portion that forms a ring in the cyclic structure (heterocyclic structure).
• the cyclic structure may be a single ring, multiple rings, or a combination of these.
• the cyclic structure may be an alicyclic structure, an aromatic ring structure, a heterocyclic structure, or a combination of these.
• the ring structures may be bonded to form a chain structure, or two or more ring structures may form a condensed ring structure, a bridged ring structure, or a spiro ring structure.
• a divalent heteroatom-containing group may be present between the carbon-carbons forming the skeleton of the cyclic structure or chain structure, and some or all of the hydrogen atoms on the carbon atoms of the cyclic structure or chain structure may be substituted with other substituents.
• alicyclic structure a structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in R 18 of the above formula (3) can be suitably adopted.
• aromatic rings including aromatic hydrocarbon rings and heteroaromatic rings
• the aromatic rings shown in the above-mentioned iodine group-containing aromatic ring structure can be suitably used.
• heterocyclic structure examples include oxygen atom-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; Nitrogen-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur-containing aliphatic heterocyclic structures such as thietane, thiolane, and thiane; Aliphatic 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 heteroatoms, such as oo
• the heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal, or a combination thereof.
• Examples of such structures include structures represented by the following formulas (H-1) to (H-11).
• ⁇ is an integer from 1 to 3.
• divalent heteroatom-containing groups examples include -CO-, -CS-, -NR'-, -O-, -S-, -SO 2 - and divalent groups combining these, etc.
• R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.
• the acid anion portion is a sulfonate anion, and it is preferable that a fluorine atom or a fluorinated hydrocarbon group is bonded to the carbon atom adjacent to the sulfur atom of the sulfonate anion. This allows the radiation-sensitive acid generator to efficiently exert the above-mentioned functions.
• the radiation-sensitive acid generator is preferably represented by the following formula (G-1):
• L 1 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.
• R 1 and R 2 are each independently a hydroxy group, a sulfo group, or a sulfanyl group.
• R 3 and R 4 are each independently a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, or an alkylsulfonyloxy group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group, or an alkoxy group having 1 to 10 carbon atoms, or -NR 8 -C( ⁇ O)-R 9 or -NR 8 -C( ⁇ O)-O-R 9 , R 8 is a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms which may contain a halogen atom, a hydroxy group, an al
• R 3 preferred as R 3 are a hydroxy group, --NR 8 --C(.dbd.O)--R 9 , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like.
• R 5 is a single bond or a divalent linking group having 1 to 20 carbon atoms
• R 5 is a (g 1 +1)-valent linking group having 1 to 20 carbon atoms.
• the linking group include a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 18 in the above formula (3), a group having the above divalent heteroatom-containing group between the carbon and carbon of this hydrocarbon group (between two adjacent or non-adjacent carbon atoms), a group in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group, or a group combining these.
• Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.
• the linking group preferably contains -O-, -S-, -NR LL -, -CO-, the above cyclic structure, or a combination thereof.
• R LL is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.
• Rf 1 to Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group.
• Rf 1 and Rf 2 may combine to form a carbonyl group.
• Rf 3 and Rf 4 are both fluorine atoms.
• g 1 is an integer of 1 to 3.
• g 2 and g 3 are each independently an integer of 0 to 2.
• g 4 is 0 or 1.
• g 5 is an integer of 0 to 3.
• g 6 is an integer of 0 to 2.
• g 7 is 0 or 1.
• g 2 +g 5 is preferably an integer of 1 to 5, more preferably an integer of 1 to 3.
• g 4 is 0, g 2 is preferably 1 or 2.
• g 4 is 1, g 2 is preferably 0 and g 5 is preferably an integer of 1 to 3.
• First organic acid anions of the radiation-sensitive acid generator represented by the above formula (G-1) include, but are not limited to, those shown below. Note that, instead of the first organic acid anion having an iodine group-containing aromatic ring structure, a first organic acid anion not having an iodine group-containing aromatic ring structure can preferably have a structure in which the iodine group in the following formula is replaced with an atom or group other than the iodine group, such as a hydrogen atom or other substituent.
• the first onium cation preferably contains at least one of a fluoro group and an iodine group.
• the first onium cation preferably contains an aromatic ring having a fluoro group (hereinafter also referred to as a "fluoro group-containing aromatic ring structure").
• the fluoro group-containing aromatic ring structure includes not only a structure in which a fluoro group is directly bonded to an aromatic ring, but also a structure in which a fluoro group is bonded to an aromatic ring via another structure.
• the aromatic ring in the fluoro group-containing aromatic ring structure the aromatic ring in the iodine group-containing aromatic ring structure can be suitably adopted.
• the number of fluoro groups in the fluoro group-containing aromatic ring structure is not particularly limited, but is preferably 1, 2, 3, 4 or 5, and more preferably 1, 2, 3 or 4.
• the first onium cation more preferably contains the above-mentioned iodine group-containing aromatic ring structure as an embodiment containing an iodine group.
• the first onium cation is preferably a sulfonium cation or an iodonium cation, and more preferably a sulfonium cation.
• the first onium cation is preferably represented by the following formula (Q-1):
• Ra1 and Ra2 each independently represent a substituent.
• n1 represents an integer of 0 to 5, and when n1 is 2 or more, the multiple Ra1s may be the same or different.
• n2 represents an integer of 0 to 5, and when n2 is 2 or more, the multiple Ra2s may be the same or different.
• n3 represents an integer of 0 to 5, and when n3 is 2 or more, the multiple Ra3s may be the same or different.
• Ra3 represents a substituent.
• Ra1 and Ra2 may be linked together to form a ring. When n1 is 2 or more, multiple Ra1s may be linked together to form a ring. When n2 is 2 or more, multiple Ra2s may be linked together to form a ring.
• the substituents represented by Ra1, Ra2, and Ra3 are preferably an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a hydroxyl group, a halogen atom, or a halogenated hydrocarbon group.
• the alkyl groups of Ra1 and Ra2 may be linear or branched.
• the alkyl groups preferably have 1 to 10 carbon atoms, and examples of such alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl.
• methyl, ethyl, n-butyl, and t-butyl are particularly preferred.
• Cycloalkyl groups of Ra1 and Ra2 include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Of these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.
• the alkyl group portion of the alkoxy group of Ra1 and Ra2 can be, for example, those listed above as the alkyl group of Ra1 and Ra2.
• As the alkoxy group a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group are particularly preferred.
• Examples of the cycloalkyl group portion of the cycloalkyloxy group of Ra1 and Ra2 include those listed above as the cycloalkyl groups of Ra1 and Ra2.
• a cyclopentyloxy group and a cyclohexyloxy group are particularly preferred.
• the alkoxy group portion of the alkoxycarbonyl group of Ra1 and Ra2 may be, for example, those listed above as the alkoxy group of Ra1 and Ra2.
• As the alkoxycarbonyl group a methoxycarbonyl group, an ethoxycarbonyl group, and an n-butoxycarbonyl group are particularly preferred.
• the alkyl group moiety of the alkylsulfonyl group of Ra1 and Ra2 may, for example, be those listed above as the alkyl group of Ra1 and Ra2.
• the cycloalkyl group moiety of the cycloalkylsulfonyl group of Ra1 and Ra2 may, for example, be those listed above as the cycloalkyl group of Ra1 and Ra2.
• alkylsulfonyl groups or cycloalkylsulfonyl groups methanesulfonyl group, ethanesulfonyl group, n-propanesulfonyl group, n-butanesulfonyl group, cyclopentanesulfonyl group, and cyclohexanesulfonyl group are particularly preferred.
• Each of the groups Ra1 and Ra2 may further have a substituent.
• substituents include a halogeno group such as a fluoro group (preferably a fluoro group), a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, a cycloalkyloxy group, an alkoxyalkyl group, a cycloalkyloxyalkyl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, an alkoxycarbonyloxy group, and a cycloalkyloxycarbonyloxy group.
• halogen atoms (halogeno groups) of Ra1 and Ra2 include fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodine groups), with fluoro groups and iodine groups being preferred.
• the halogenated hydrocarbon group of Ra1 and Ra2 is preferably a halogenated alkyl group.
• the alkyl group and halogen atom constituting the halogenated alkyl group are the same as those mentioned above. Among them, a fluorinated alkyl group is preferable, and CF3 is more preferable.
• Ra1 and Ra2 may be bonded to each other to form 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.
• Ra1 and Ra2 are bonded to each other to form a ring
• it is more preferable to form -O-, -S-, or a single bond and it is particularly preferable to form a single bond.
• n1 is 2 or more
• a plurality of Ra1 may be linked to each other to form a ring
• n2 is 2 or more
• a plurality of Ra2 may be linked to each other to form a ring.
• Such an example includes an embodiment in which two Ra1 are linked to each other to form a naphthalene ring together with the benzene ring to which they are bonded.
• Ra3 is preferably a fluoro group or a group having one or more fluoro groups.
• the group having a fluoro group include groups in which the alkyl group, cycloalkyl group, alkoxy group, cycloalkyloxy group, alkoxycarbonyl group, and alkylsulfonyl group of Ra1 and Ra2 are substituted with a fluoro group.
• fluorinated alkyl groups are preferred, with CF3 , C2F5 , C3F7 , C4F9 , C5F11 , C6F13 , C7F15 , C8F17 , CH2CF3 , CH2CH2CF3 , CH2C2F5 , CH2CH2C2F5 , CH2C3F7 , CH2CH2C3F7 , CH2C4F9 and CH2CH2C4F9 being more preferred , and CF3 being particularly preferred .
• Ra3 is preferably a fluoro group or CF3 , and more preferably a fluoro group.
• n1 and n2 are each preferably an integer from 0 to 3, and more preferably an integer from 0 to 2.
• n3 is preferably an integer from 1 to 3, and more preferably 1 or 2.
• (n1+n2+n3) is preferably an integer of 1 to 15, more preferably an integer of 1 to 9, even more preferably an integer of 2 to 6, and particularly preferably an integer of 3 to 6.
• onium cations represented by the above formula (Q-1) include the following.
• the iodine group and fluoro group in the onium cations below may be substituted with a hydrogen atom or other substituents.
• the first onium cation is an iodonium cation
• it is preferably a diaryliodonium cation. More preferably, the diaryliodonium cation has one or more fluoro or iodo groups.
• the radiation-sensitive acid generator represented by the above formula (G-1) can also be synthesized by a known method, in particular a salt exchange reaction.
• a known radiation-sensitive acid generator can also be used as long as it does not impair the effects of the present invention.
• the lower limit of the content of the radiation-sensitive acid generator (total when multiple types are used) is preferably 10 parts by mass, more preferably 20 parts by mass, and even more preferably 25 parts by mass, relative to 100 parts by mass of the base polymer.
• the upper limit of the content is preferably 100 parts by mass, more preferably 90 parts by mass, and even more preferably 80 parts by mass.
• the lower limit of the content of the radiation-sensitive acid generator (total when multiple types are used) is preferably 2 parts by mass, more preferably 5 parts by mass, and even more preferably 8 parts by mass, relative to 100 parts by mass of the base polymer.
• the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass. This allows the resist pattern to exhibit excellent sensitivity, CDU performance, and LWR performance when forming the resist pattern.
• the acid diffusion controller contains a second organic acid anion and a second onium cation, and generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation.
• the acid diffusion controller does not substantially dissociate the acid-dissociable group of the base polymer under pattern formation conditions using the radiation-sensitive composition, and has the function of suppressing diffusion of the acid generated from the radiation-sensitive acid generator in unexposed areas by salt exchange.
• the acid diffusion control agent in the radiation-sensitive composition, it is possible to suppress the diffusion of acid in unexposed areas, and to form a resist pattern with superior CDU and LWR performance.
• the structure of the second organic acid anion is not specified, but it preferably contains -O-, -CO-, a cyclic structure, or a combination thereof.
• a cyclic structure in a radiation-sensitive acid generator can be suitably used.
• the second organic acid anion preferably contains the iodine group-containing aromatic ring structure.
• the second organic acid anion has a sulfonate anion or a carboxylate anion as the acid anion portion (however, when the second organic acid anion has the sulfonate anion, neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom adjacent to the sulfur atom of the sulfonate anion). This allows the acid diffusion control agent to efficiently exert the second function.
• Examples of the acid diffusion control agent include a sulfonium salt compound represented by the following formula (8-1) and an iodonium salt compound represented by the following formula (8-2).
• Other examples include a compound containing a sulfonium cation and an anion in the same molecule represented by the following formula (8-3) and a compound containing an iodonium cation and an anion in the same molecule represented by the following formula (8-4).
• J + is a sulfonium cation
• U + is an iodonium cation
• E - and Q - are each independently a second organic acid anion represented by OH - , R ⁇ -COO - , or R ⁇ -SO 3 - .
• R ⁇ is a monovalent organic group having 1 to 30 carbon atoms.
• R ⁇ is a single bond or a divalent organic group having 1 to 30 carbon atoms.
• this organic group examples include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between the carbon atoms of this hydrocarbon group or at the carbon chain end, a group in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group, or a combination thereof.
• a monovalent hydrocarbon group having 1 to 20 carbon atoms in the organic group a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 18 in the above formula (3) can be suitably used.
• a divalent heteroatom-containing group and monovalent heteroatom-containing group a divalent heteroatom-containing group and monovalent heteroatom-containing group in the above radiation-sensitive acid generator can be suitably used.
• the second organic acid anion of the acid diffusion control agent includes, but is not limited to, those shown below. Examples include a compound containing an iodonium cation and an anion in the same molecule and a compound containing a sulfonium cation and an anion in the same molecule.
• a structure in which the iodo group in the following formula is replaced with an atom or group other than the iodo group, such as a hydrogen atom or other substituent can be preferably used.
• the second onium cation is preferably a sulfonium cation or an iodonium cation, and more preferably a sulfonium cation.
• the second onium cations preferably each independently contain at least one of a fluoro group and an iodine group. It is more preferable that the second onium cation contains the fluoro group-containing aromatic ring structure as an embodiment containing a fluoro group. It is more preferable that the second onium cation contains the iodine group-containing aromatic ring structure as an embodiment containing an iodine group.
• the first onium cation in the radiation-sensitive acid generator can be suitably used.
• the second onium cation is an iodonium cation
• it is preferably a diaryliodonium cation. More preferably, the diaryliodonium cation has one or more fluoro groups.
• the acid diffusion control agent can be synthesized by a known method, particularly a salt exchange reaction.
• 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 control agents may be used alone or in combination of two or more.
• the lower limit of the content of the acid diffusion control agent (total when multiple types are used) is preferably 2 parts by mass, more preferably 5 parts by mass, and even more preferably 8 parts by mass, relative to 100 parts by mass of the base polymer.
• the upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 25 parts by mass.
• the radiation-sensitive composition according to the present embodiment contains a solvent.
• the solvent is not particularly limited as long as it is capable of dissolving or dispersing the base polymer, the radiation-sensitive acid generator, the acid diffusion controller, and additives that are optionally contained.
• solvents examples 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, and diacetone alcohol; 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.
• 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 and ether-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents and polyhydric alcohol partial ether-based solvents are more preferred, and propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether are 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 a base polymer, a radiation-sensitive acid generator, an acid diffusion controller, and a solvent, and, if necessary, other optional components, 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 above-mentioned pattern formation method uses the above-mentioned radiation-sensitive composition, which is capable of exhibiting excellent sensitivity, CDU performance, and LWR performance during pattern formation, and therefore can form a high-quality resist pattern. Each step will be 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 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 target 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 monomer solution prepared above was dropped over 3 hours, and then heated at 85°C for another 3 hours, and the polymerization reaction was carried out for a total of 6 hours.
• the polymerization solution was cooled to room temperature.
• the cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off.
• the filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass).
• the start of the dropwise addition was set as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours.
• the polymerization solution was cooled with water to 30°C or less.
• the solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was collected. This operation was repeated three times.
• acetonitrile 400 parts by mass
• hexane 100 parts by mass
• B-1 to B-6 Compounds represented by the following formulas (B-1) to (B-6)
• a radiation-sensitive composition (J-1) was prepared by mixing 100 parts by mass of (P-1) as the polymer [A], 50 parts by mass of (A-1) as the radiation-sensitive acid generator, 15 parts by mass of (B-6) as the acid diffusion controller, 7.0 parts by mass of (E-2) as the high fluorine content polymer, and 4,280 parts by mass of (F-1) and 1,830 parts by mass of (F-2) as the solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 ⁇ m.
• 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.
• the radiation-sensitive composition for EUV exposure prepared above was applied onto this lower anti-reflective coating using the spin coater, and 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 55 nm.
• the exposure dose required to form a 32 nm line-and-space pattern was defined as the optimum exposure dose Eop, and this optimum exposure dose was defined as the sensitivity (mJ/ cm2 ).
• the sensitivity was evaluated as "good” when it was 35 mJ/cm2 or less , and as “poor” when it exceeded 35 mJ/ cm2 .
• CDU performance A resist pattern was formed by adjusting the mask size so that a 25 nm contact hole pattern was formed by irradiating the exposure dose of Eop obtained above. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. The hole diameter was measured at 16 points in the range of 500 nm to obtain the average value, and the average value was measured at a total of 500 points at any point, and a 1 sigma value was obtained from the distribution of the measured values, which was defined as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period and the better it is. The CDU performance can be evaluated as "good” when it is 2.0 nm or less, and as “poor” when it exceeds 2.0 nm.
• LWR performance A resist pattern was formed by adjusting the mask size so that a 32 nm line and space pattern was formed by irradiating the optimal exposure dose Eop obtained by the above sensitivity evaluation. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. A total of 50 points of line width variation were measured, and a 3 sigma value was obtained from the distribution of the measured values, and this 3 sigma value was taken as the LWR performance (nm). The smaller the LWR value, the smaller the line rattle and the better it was. The LWR performance was evaluated as "good” when it was 2.5 nm or less, and as “poor” when it exceeded 2.5 nm.
• the radiation-sensitive compositions of the examples all had good performance in terms of sensitivity, CDU, and LWR.
• a resist pattern having high sensitivity and excellent CDU and LWR performance can be formed, and therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become increasingly finer in the future.

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