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
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/0046—Photosensitive materials with perfluoro compounds, e.g. for dry lithography
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
  • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition
  • G03F7/0397—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition the macromolecular compound having an alicyclic moiety in a side chain
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/20—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
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
  • G03F7/2004—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light

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 resist materials containing polymers with benzene rings that have improved radiation absorption efficiency are also being considered. (WO 2021/106535).
• next-generation technologies require a sufficient level of development defect suppression, which suppresses defects during development, in addition to various resist performances such as critical dimension uniformity (CDU) performance, which is an index of sensitivity and uniformity of line width and hole diameter.
• CDU critical dimension uniformity
• the present invention aims to provide a radiation-sensitive composition and a pattern formation method that can achieve sufficient levels of sensitivity, CDU performance, and development defect suppression when next-generation technology is applied.
• p and q are each preferably independently an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2.
• p is preferably 2.
• R ⁇ has the same meaning as in the above formula (1).
• the lower limit of the content of the structural unit (I) in the polymer is preferably 1 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on all structural units constituting the polymer.
• the upper limit of the above content is preferably 50 mol%, more preferably 40 mol%, even more preferably 30 mol%, and particularly preferably 20 mol%.
• the structural unit (II) is a structural unit having a phenolic hydroxyl group. However, the structural unit (II) does not include those corresponding to the structural unit (I) and those corresponding to the structural unit (III) described below.
• the polymer contains the structural unit (II)
• 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 with 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 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-- * .
• Examples of the alkyl group in R 102 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.
• 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 (2-10) (hereinafter also referred to as “structural unit (2-1) to structural unit (2-10)").
• R ⁇ is the same as in the above formula (2).
• the lower limit of the content of the structural unit (II) (the total content when multiple types of structural unit (II) are present) is preferably 10 mol%, more preferably 15 mol%, and even more preferably 20 mol% relative to all structural units constituting the polymer.
• the upper limit of the above content is preferably 60 mol%, more preferably 55 mol%, and even more preferably 45 mol%.
• the structural unit (III) is a structural unit having an acid dissociable group. However, the structural unit (III) does not include those corresponding to the structural unit (II).
• the structural unit (III) 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. From the viewpoint of improving the pattern formability of the radiation-sensitive composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (III-1)”) is preferred.
• 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 L 11a may have include 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, and an alkoxy group.
• alkyl group fluorinated alkyl group, alkoxycarbonyloxy group, acyl group, and acyloxy group as the substituent of L 11a
• the corresponding groups exemplified for R 102 in the above formula (2) can be suitably used.
• alkoxy group a linear or branched alkoxy group having 1 to 8 carbon atoms, such as a methoxy group, an ethoxy group, or a propoxy group, can be mentioned.
• 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 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
• Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R 18 to R 20 above include monovalent linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and monovalent linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.
• 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.
• structural unit (III-1) examples include structural units represented by the following formulas (3-1) to (3-9) (hereinafter also referred to as “structural units (III-1-1) to (III-1-9)").
• R 17 to R 20 are the same as those 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 0 or 1.
• 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 or an ethyl group.
• 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 (III) (the total content when multiple types of structural unit (III) are present) is more preferably 20 mol%, further preferably 30 mol%, and particularly preferably 40 mol% relative to all structural units constituting the base resin.
• the upper limit of the above content is preferably 70 mol%, more preferably 60 mol%, further preferably 50 mol%, and particularly preferably 70 mol%.
• the structural unit (IV) 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 (IV), 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.
• structural unit (IV) examples 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 of -CO-, -O-, -NH-, and -S-.
• the structural unit (IV) 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 (IV) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on all structural units constituting the base polymer.
• the upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol% or less.
• the base polymer can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a known radical polymerization initiator or the like.
• 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 5,000.
• the upper limit of the Mw is preferably 20,000, more preferably 15,000, even more preferably 10,000, and particularly preferably 8,000. If the Mw of the polymer is within the above range, the heat resistance and developability of the resulting resist film are good.
• the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base polymer (Mw/Mn) measured 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 Mw and Mn of the polymer are values measured by gel permeation chromatography (GPC) under the following conditions.
• GPC columns 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40°C Elution solvent: tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass Sample injection volume: 100 ⁇ L Detector: Differential refractometer Standard material: Monodisperse polystyrene
• the polymer content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total solid content of the radiation-sensitive composition.
• the high fluorine content polymer is a polymer having a higher mass content of fluorine atoms than the base polymer.
• the high fluorine content polymer is preferably unevenly distributed in the surface layer of the resist film relative to the base polymer, but is not necessarily limited to this.
• the high fluorine content polymer preferably has a structure in which its solubility in an alkaline aqueous solution changes due to the action of an alkali. This improves the solubility of the resist film in an alkaline developer during development, making it possible to suppress the occurrence of development defects.
• the high fluorine content polymer preferably has a fluorine atom-containing structural unit represented by the following formula (f-1) (hereinafter also referred to as structural unit (V)).
• structural unit (V) By having the structural unit (V), the high fluorine content polymer has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.
• 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 (V) 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.
• dissociation of an acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.
• the onium salt which gives a sulfonic acid upon exposure to light is (1) A compound having one or more fluorine atoms or fluorinated hydrocarbon groups bonded to a carbon atom at the ⁇ - or ⁇ -position relative to a sulfur atom of a sulfonate anion, (2) A compound in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom at the ⁇ - or ⁇ -position to the sulfur atom of the sulfonate anion.
• the radiation-sensitive acid generator is preferably one that falls under the above category (1).
• the acid diffusion controller is preferably one that falls under the above category (2), (3) or (4), and more preferably one that falls under category (2) or (4).
• the onium cation in the radiation-sensitive acid generator represented by formula (A-1) above is preferably represented by formula (Q-1) below.
• 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 preferably represents a fluorine atom or a group having one or more fluorine atoms.
• 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.
• Ra1 and Ra2 may be linked together to form a ring (i.e., a heterocycle containing a sulfur atom).
• the substituents represented by Ra1 and Ra2 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 halogen atom such as a fluorine atom (preferably a fluorine atom), 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.
• the halogen atoms of Ra1 and Ra2 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom and an iodine atom 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.
• the onium cation in the acid diffusion controller represented by the above formulas (S-1) and (S-2) the onium cation in the radiation-sensitive acid generator can be suitably used.
• 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 present) is preferably 10 parts by mass, more preferably 20 parts by mass, even more preferably 30 parts by mass, and particularly preferably 40 parts by mass, relative to 100 parts by mass of the base polymer.
• the upper limit of the content is preferably 70 parts by mass, more preferably 60 parts by mass, and even more preferably 50 parts by mass. This allows excellent sensitivity and CDU performance to be exhibited when forming a resist pattern.
• the radiation-sensitive composition according to the present embodiment contains a solvent.
• the solvent is not particularly limited as long as it is a solvent that can dissolve or disperse at least the base polymer, the high fluorine content polymer, and the onium salt, as well as 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.
• 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 high-fluorine content polymer, an onium salt, 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 onto 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 (hereinafter, also referred to as the "developing step”).
• the pattern formation method described above uses the radiation-sensitive composition, which has excellent sensitivity and CDU performance in the exposure process and excellent development defect suppression in the development process, and therefore can form a high-quality resist pattern. Each process 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 or 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 140° C., and preferably 80° C. to 120° C.
• the PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.
• the thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.
• the exposure step is carried out with radiation having a wavelength of 50 nm or less
• the resist film formed in the resist film forming step (1) above is irradiated with radiation through a photomask (or, in some cases, through an immersion medium such as water) to expose the resist film.
• radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; charged particle beams such as electron beams and alpha rays, depending on the line width of the 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 130°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. 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
• Mw Weight average molecular weight
• Mn number average molecular weight
• Polymer Synthesis Examples 2 to 29 Synthesis of Polymers (A-2) to (A-29)] Polymers (A-2) to (A-29) were synthesized in the same manner as in Polymer Synthesis Example 1, except that the monomer compositions shown in Table 1 were used.
• [Example 1] [A] 100 parts by mass of polymer (A-1), [F] 3 parts by mass of polymer (F-1) in terms of solid content, [B] 45 parts by mass of (B-1) as a radiation-sensitive acid generator, [D] 45 mol% of (D-1) as an acid diffusion controller relative to the anion of (B-1), [E] 5,500 parts by mass of (E-1) as a solvent, and 1,500 parts by mass of (E-2) were blended. This was filtered through a membrane filter having a pore size of 0.2 ⁇ m to prepare radiation-sensitive composition (R-1).
• the resist film was PEB (post-exposure bake) at 100°C for 60 seconds.
• PEB post-exposure bake
• development was performed using a 2.38 wt % aqueous TMAH solution at 23° C. for 30 seconds to form a positive type 50 nm pitch, 25 nm contact hole pattern.
• the resist patterns thus formed were measured according to the following methods to evaluate the sensitivity, CDU performance, and number of development defects of each radiation-sensitive composition.
• a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns. The evaluation results are shown in Table 3 below.
• the exposure dose required to form a 25 nm contact hole pattern was determined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ/ cm2 ).
• Sensitivity was judged as "A” (very good) when it was less than 57 mJ/ cm2 , "B” (good) when it was 57 mJ/ cm2 or more and 60 mJ/cm2 or less , and "C” (poor) when it exceeded 60 mJ/ cm2 .
• CDU performance The 25 nm contact hole pattern was observed from above using the above scanning electron microscope, and a total of 800 holes were measured at arbitrary points. The dimensional variation (3 ⁇ ) was determined and this was taken 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 was judged as "A” (very good) when it was less than 3.6 nm, "B” (good) when it was 3.6 nm or more and less than 3.8 nm, and "C” (bad) when it was 3.8 nm or more.
• the resist film was exposed to an optimal exposure dose and developed to form a 25 nm contact hole pattern.
• the number of defects on the wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Among the defects measured, defects with a diameter of 0.5 ⁇ m or less were judged to be originating from the resist film.
• the number of developed defects was judged as "A" (very good) when the number of defects judged to be originating from the resist film was less than 30, "B" (good) when the number was 30 to 50, and "C” (bad) when the number was more than 50.
• the radiation-sensitive compositions of the examples had better sensitivity, CDU performance, and development defect suppression than the comparative examples.
• the radiation-sensitive composition and resist pattern forming method of the present invention can improve sensitivity, CDU performance, and number of development defects compared to conventional methods. Therefore, they can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

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