Radiation-sensitive resin composition and resist pattern forming method

Abstract

To provide a radiation-sensitive resin composition and a resist pattern forming method which are capable of forming a resist pattern good in sensitivity to exposure light and excellent in LWR performance and resolution.SOLUTION: The radiation-sensitive resin composition contains: a polymer having a first structural unit containing a phenolic hydroxyl group; a compound represented by formula (1-1) or formula (1-2); and a specific compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive resin composition and a resist pattern forming method.

Background Art

[0002] The radiation-sensitive resin composition used for microfabrication by lithography generates an acid in the exposed area by irradiation with radiation such as far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet rays (EUV) (wavelength 13.5 nm), and charged particle beams such as electron beams. A resist pattern is formed on the substrate by causing a difference in the dissolution rate of the exposed area and the unexposed area in the developer by a chemical reaction using this acid as a catalyst.

[0003] In addition to having good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, the radiation-sensitive composition is required to have excellent LWR (Line Width Roughness) performance indicating line width uniformity and resolution.

[0004] Regarding these requirements, the types, molecular structures, etc. of the polymer, acid generator, and other components used in the radiation-sensitive resin composition have been studied, and furthermore, their combinations have also been studied in detail (see JP-A-2010-134279, JP-A-2014-224984, and JP-A-2016-047815).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] At present, as the miniaturization of resist patterns has advanced to the level of a line width of 40 nm or less, the required level of the above performance has further increased, and the above conventional radiation-sensitive resin composition cannot satisfy the above requirements.

[0007] The present invention has been made based on the above circumstances, and an object thereof is to provide a radiation-sensitive resin composition and a resist pattern forming method capable of forming a resist pattern having good sensitivity to exposure light and excellent LWR performance and resolution.

Means for Solving the Problems

[0008] The invention made to solve the above problems is a radiation-sensitive resin composition containing a polymer having a first structural unit containing a phenolic hydroxyl group (hereinafter, also referred to as "[A] polymer"), a compound represented by the following formula (1-1) or formula (1-2) (hereinafter, also referred to as "[B] acid generator"), and a compound represented by the following formula (2) (hereinafter, also referred to as "[C] acid diffusion controller").

Chemical formula

Chemical formula

[0009] Another invention made to solve the above problems is a resist pattern forming method including a step of coating the above-described radiation-sensitive resin composition directly or indirectly on a substrate, a step of exposing the resist film formed by the above coating step, and a step of developing the exposed resist film.

Advantages of the Invention

[0010] According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern having good sensitivity to exposure light and excellent LWR performance and resolution can be formed. Therefore, these can be suitably used in a semiconductor device processing process or the like where further miniaturization is expected in the future.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the radiation-sensitive resin composition and resist pattern forming method of the present invention will be described in detail.

[0012] <Radiation-sensitive resin composition> The radiation-sensitive resin composition contains [A] a polymer, [B] an acid generator, and [C] an acid diffusion controller. The radiation-sensitive resin composition usually contains an organic solvent (hereinafter also referred to as "[D] organic solvent"). The radiation-sensitive resin composition may contain other optional components as long as the effects of the present invention are not impaired.

[0013] By containing [A] a polymer, [B] an acid generator, and [C] an acid diffusion controller, the radiation-sensitive resin composition has good sensitivity to exposure light and can form a resist pattern excellent in LWR performance and resolution. The reason why the radiation-sensitive resin composition exhibits the above effects when having the above configuration is not necessarily clear, but can be speculated as follows, for example. That is, since the [B] acid generator contained in the radiation-sensitive resin composition has a cation of a specific structure, it becomes easier to absorb exposure light, and the acid generation efficiency by exposure is improved. As a result, it is considered that the radiation-sensitive resin composition has good sensitivity to exposure light and can form a resist pattern excellent in LWR performance and resolution.

[0014] Hereinafter, each component contained in the radiation-sensitive resin composition will be described.

[0015] <[A] Polymer> [A] The polymer has a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (I)" or "first structural unit").

[0016] [A] The polymer preferably further has a structural unit containing an acid dissociable group that dissociates by the action of an acid to give a carboxy group (hereinafter also referred to as "structural unit (II)" or "second structural unit"). [A] The polymer preferably further has a structural unit containing a partial structure represented by the following formula (5) described later (hereinafter also referred to as "structural unit (III)" or "third structural unit"). [A] The polymer may further have other structural units other than structural units (I) to (III) (hereinafter simply also referred to as "other structural units"). The radiation-sensitive resin composition can contain one or more [A] polymers.

[0017] Hereinafter, each structural unit possessed by the [A] polymer will be described.

[0018] [Structural unit (I)] Structural unit (I) is a structural unit containing a phenolic hydroxyl group. The "phenolic hydroxyl group" refers not only to a hydroxyl group directly bonded to a benzene ring but also to all hydroxyl groups directly bonded to an aromatic ring.

[0019] In the case of KrF exposure, EUV exposure, or electron beam exposure, since the [A] polymer has structural unit (I), the sensitivity of the radiation-sensitive resin composition to the exposure light can be further enhanced. Therefore, the radiation-sensitive resin composition can be suitably used as a radiation-sensitive resin composition for KrF exposure, EUV exposure, or electron beam exposure.

[0020] Examples of structural unit (I) include structural units represented by the following formulas (I-1) to (I-14) (hereinafter also referred to as "structural units (I-1) to (I-14)") and the like.

[0021]

Chemical formula

[0022] In the above formulas (I-1) to (I-14), R P is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0023] R P From the viewpoint of the copolymerizability of the monomer that gives the structural unit (I), a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable.

[0024] As the structural unit (I), a structural unit (I-1), a structural unit (I-2) or a combination thereof is preferable.

[0025] As the lower limit of the content ratio of the structural unit (I) in the [A] polymer, 10 mol% is preferable, 20 mol% is more preferable, and 25 mol% is even more preferable with respect to all the structural units constituting the [A] polymer. As the upper limit of the above content ratio, 80 mol% is preferable, 60 mol% is more preferable, and 50 mol% is even more preferable. By setting the content ratio of the structural unit (I) within the above range, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further enhanced.

[0026] [Structural unit (II)] The structural unit (II) is a structural unit containing an acid dissociable group (hereinafter, also referred to as "acid dissociable group (a)") that dissociates by the action of an acid to give a carboxy group. The "acid dissociable group (a)" is a group that replaces the hydrogen atom in the carboxy group and dissociates by the action of an acid to give a carboxy group. By the action of the acid generated from the [B] acid generator upon exposure, the acid dissociable group (a) dissociates, and a difference in solubility of the [A] polymer in the developer between the exposed portion and the unexposed portion occurs, whereby a resist pattern can be formed.

[0027] Examples of the structural unit (II) include structural units represented by the following formulas (4-1) to (4-3) (hereinafter, also referred to as "structural units (II-1) to (II-3)"). In the following formula (4-1), for example, -C(R X )(RY )(R Z ) corresponds to the acid dissociable group (a).

[0028] [Chemical formula]

[0029] In the above formulas (4-1), (4-2) and (4-3), R T is, independently of one another, a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0030] In the above formula (4-1), R X is, independently of one another, a monovalent hydrocarbon group having 1 to 20 carbon atoms. R Y and R Z are, independently of one another, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other and are part of an alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are attached.

[0031] In the above formula (4-2), R A is a hydrogen atom. R B and R C are, independently of one another, a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R D is R A , R B and R C is a divalent hydrocarbon group having 1 to 20 carbon atoms that forms an unsaturated alicyclic structure having 4 to 20 ring members together with the carbon atoms to which they are respectively attached.

[0032] In the above formula (4-3), R U and R V are, independently of one another, a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R W is, independently of one another, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R U and R V are combined with each other and are part of an alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are attached, or R U and R Ware aligned with each other and R U is the carbon atom to which R is bonded and R W is part of an aliphatic heterocyclic structure having 5 to 20 ring members, which is composed of the carbon atom to which R is bonded and the oxygen atom to which R is bonded.

[0033] In this specification, the "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. This "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a chain structure, and includes both a straight-chain hydrocarbon group and a branched hydrocarbon group. The "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as the ring structure and does not contain an aromatic ring structure, and includes both a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. However, it is not necessary to be composed only of an alicyclic structure, and a chain structure may be included in a part thereof. The "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as the ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a chain structure or an alicyclic structure may be included in a part thereof.

[0034] R X 、R Y 、R Z 、R B 、R C 、R U 、R V or R W Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0035] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group; alkenyl groups such as ethenyl group, propenyl group, butenyl group; alkynyl groups such as ethynyl group, propynyl group, butynyl group, and the like.

[0036] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include alicyclic saturated hydrocarbon groups such as cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group, tricyclodecyl group, and tetracyclododecyl group; alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group, cyclohexenyl group, norbornenyl group, tricyclodecenyl group, and tetracyclododecenyl group.

[0037] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and anthryl group; aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

[0038] R Y and R Z Examples of the alicyclic structure having 3 to 20 ring members formed by combining R with each other and together with the carbon atom to which they are attached include monocyclic saturated alicyclic structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, and cyclohexane structure; polycyclic saturated alicyclic structures such as norbornane structure and adamantane structure; monocyclic unsaturated alicyclic structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, and cyclohexene structure; polycyclic unsaturated alicyclic structures such as norbornene structure.

[0039] R D Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R X include groups obtained by removing one hydrogen atom from the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R Y 、R Z 、R B 、R C 、R U 、R V or R W .

[0040] R D is R A 、R B and R C Examples of the unsaturated alicyclic structure having 4 to 20 ring members formed together with the carbon atoms to which they are respectively bonded include monocyclic unsaturated alicyclic structures such as cyclobutene structure, cyclopentene structure, cyclohexene structure; polycyclic unsaturated alicyclic structures such as norbornene structure and the like.

[0041] R U and R V Examples of the alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are bonded when R Y and R Z are combined with each other include structures similar to the structures exemplified as the alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are bonded when R

[0042] R U and R W are combined with each other and R U is bonded to the carbon atom and R W Examples of the aliphatic heterocyclic structure having 5 to 20 ring members formed together with the oxygen atom to which it is bonded include saturated oxygen-containing heterocyclic structures such as oxacyclobutane structure, oxacyclopentane structure, oxacyclohexane structure; unsaturated oxygen-containing heterocyclic structures such as oxacyclobutene structure, oxacyclopentene structure, oxacyclohexene structure and the like.

[0043] R T From the viewpoint of the copolymerizability of the monomer giving the structural unit (I), a hydrogen atom or a methyl group is preferable.

[0044] R X is preferably a chain hydrocarbon group or an aromatic hydrocarbon group, more preferably an alkyl group or an aryl group, and even more preferably a methyl group, an ethyl group, an i-propyl group, a tert-butyl group or a phenyl group.

[0045] RY and R Z Preferably, they are part of an alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are attached and to which they are bonded. The alicyclic structure is preferably a saturated alicyclic structure, more preferably a monocyclic saturated alicyclic structure, and even more preferably a cyclopentane structure or a cyclohexane structure. R Y and R Z When they are part of an alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are attached and to which they are bonded, R X is preferably an alkyl group, an ethenyl group or a phenyl group. In particular, when the alicyclic structure contains a norbornane skeleton, R X is preferably an alkyl group, and more preferably an ethyl group.

[0046] In the above formula (4-1), R Y and R Z Examples of the alicyclic structure having 3 to 20 ring members containing a norbornane skeleton formed together with the carbon atoms to which they are attached and to which they are bonded include structures represented by the following formula. In the following formula, R X has the same meaning as described above, and * represents a bond.

[0047]

Chemical formula

[0048] R B is preferably a hydrogen atom.

[0049] [[ID=3:8]] R C is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom or a methyl group.

[0050] R D is R A R B and R C Examples of the unsaturated alicyclic structure having 4 to 20 ring members formed together with the carbon atoms to which they are respectively bonded include monocyclic unsaturated alicyclic structures, and more preferably cycloheptane structures or cyclohexene structures.

[0051] As the structural unit (II), the structural unit (II-1) or the structural unit (II-2) is preferred.

[0052] As the structural unit (II-1), the structural units represented by the following formulas (II-1-1) to (II-1-5) (hereinafter, also referred to as "structural units (II-1-1) to (II-1-5)") are preferred.

[0053]

Chemical formula

[0054] In the above formulas (II-1-1) to (II-1-5), R T has the same meaning as the above formula (4-1).

[0055] As the structural unit (II-2), the structural units represented by the following formulas (II-2-1) to (II-2-2) (hereinafter, also referred to as "structural units (II-2-1) to (II-2-2)") are preferred.

[0056]

Chemical formula

[0057] In the above formulas (II-2-1) and (II-2-2), R T has the same meaning as the above formula (4-2).

[0058] In the structural unit (II), it is also preferable that the acid dissociable group (a) is separated from the polymer main chain by at least 5 atoms in terms of the number of atoms. The "polymer main chain" refers to the longest atomic chain among the atomic chains constituting the polymer. When the acid dissociable group (a) is separated from the polymer main chain by at least 5 atoms in terms of the number of atoms, a structural unit having a partial structure represented by -CO-O-J-CO-O- between the polymer main chain and the acid dissociable group (a) is preferable. Here, J is a divalent organic group having 1 to 20 carbon atoms, the carbon atom of the carbonyl group is bonded to the polymer main chain, and the etheric oxygen atom is bonded to the acid dissociable group. As the divalent organic group having 1 to 20 carbon atoms, the groups exemplified as the divalent organic group having 1 to 20 carbon atoms in the above R 8 include the same groups as those exemplified. For example, when J in the above partial structure is a methylene group, the acid dissociable group (a) is separated from the polymer main chain by 5 atoms in terms of the number of atoms. As J, an alkanediyl group having 1 to 10 carbon atoms is preferable, an alkanediyl group having 1 to 6 carbon atoms is more preferable, an alkanediyl group having 1 to 3 carbon atoms is further preferable, and a methylene group or a 1,2-ethanediyl group is particularly preferable.

[0059] When the [A] polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) in the [A] polymer is preferably 30 mol%, more preferably 40 mol%, and further preferably 50 mol% with respect to all the structural units constituting the [A] polymer. The upper limit of the above content ratio is preferably 90 mol%, more preferably 80 mol%, and further preferably 70 mol%. By setting the content ratio of the structural unit (II) within the above range, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further enhanced.

[0060] [Structural unit (III)] The structural unit (III) is a structural unit containing a group represented by the following formula (5). By further having the structural unit (III) in the [A] polymer, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further improved.

[0061] [Chemistry]

[0062] In the above formula (5), R 12 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R 13 and R 14 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. ** indicates the bonding site with the part other than the group represented by the above formula (5) in the above third structural unit.

[0063] In this specification, the "organic group" means a group containing at least one carbon atom.

[0064] R 12 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group between carbon-carbon atoms of the above hydrocarbon group (hereinafter, also referred to as "group (α)"), a group in which a part or all of the hydrogen atoms of the above hydrocarbon group are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (β)"), a group in which a part or all of the hydrogen atoms of the above group (α) are substituted with a monovalent heteroatom-containing group (hereinafter, also referred to as "group (γ)"), and the like.

[0065] R 13 [[ID=2⑨]]and R 14 Examples of the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by include a group in which at least one hydrogen atom of a monovalent hydrocarbon group having 1 to 10 carbon atoms is substituted with a fluorine atom. Specifically, partially fluorinated alkyl groups such as fluoromethyl group, difluoromethyl group, difluoroethyl group, trifluoroethyl group, trifluoropropyl group; perfluoroalkyl groups such as trifluoromethyl group, pentafluoroethyl group, hexafluoropropyl group, etc. are included.

[0066] R 12 is preferably a hydrogen atom.

[0067] R 13 and R 14As the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms is preferable, the monovalent perfluoroalkyl group having 1 to 10 carbon atoms is more preferable, and the trifluoromethyl group is even more preferable.

[0068] As the group represented by the above formula (5), a hydroxybis(perfluoroalkyl)methyl group is preferable, and a hydroxybis(trifluoromethyl)methyl group is more preferable.

[0069] Examples of the structural unit (III) include structural units represented by the following formulas (III-1) to (III-2) (hereinafter, also referred to as "structural units (III-1) to (III-2)").

[0070]

Chemical formula

[0071] In the above formulas (III-1) and (III-2), R Q is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z is a group represented by the above formula (5).

[0072] In the above formula (III-1), L 1 is a single bond or a divalent organic group having 1 to 20 carbon atoms.

[0073] In the above formula (III-2), L 2 is a single bond or a divalent organic group having 1 to 20 carbon atoms. R 15 、R 16 and R 17 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. s is an integer of 1 to 4. When s is 2 or more, a plurality of R 15 are the same or different, a plurality of R 16 are the same or different, and a plurality of R 17 are the same or different.

[0074] L 1 and L 2 Examples of the divalent organic group having 1 to 20 carbon atoms represented by include, for example, R in the above formula (5)12 Examples thereof include a group obtained by removing one hydrogen atom from the groups exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by the formula.

[0075] R 15 、R 16 and R 17 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R 12 include the same groups as those exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by the above formula (5).

[0076] In the above formula (III-1), R Q is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

[0077] In the above formula (III-2), R Q is preferably a hydrogen atom.

[0078] L 1 is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0079] L 2 is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a divalent chain hydrocarbon group having 1 to 20 carbon atoms.

[0080] R 15 and R 16 are preferably hydrogen atoms.

[0081] R 17 is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0082] s is preferably 1.

[0083] As the structural unit (III-1), a structural unit represented by the following formula (III-1-1) (hereinafter, also referred to as "structural unit (III-1-1)") is preferable, and as the structural unit (III-2), a structural unit represented by the following formula (III-2-1) (hereinafter, also referred to as "structural unit (III-2-1)") is preferable.

[0084] [Chemical formula]

[0085] In the above formulas (III-1-1) and (III-2-1), R Q and Z are synonymous with the above formulas (III-1) and (III-2), respectively.

[0086] When the [A] polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) in the [A] polymer is preferably 1 mol% and more preferably 5 mol% with respect to all the structural units constituting the [A] polymer. The upper limit of the above content ratio is preferably 30 mol% and more preferably 20 mol%. By setting the content ratio of the structural unit (III) within the above range, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further enhanced.

[0087] [Structural unit (IV)] The structural unit (IV) is a structural unit containing a partial structure that generates sulfonic acid upon exposure. By further having the structural unit (IV) in the [A] polymer, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further improved. Examples of the monomer that provides such a structural unit include monomers represented by the following formula. Note that R A in the following formula is a hydrogen atom or a methyl group.

[0088] [Chemical formula]

[0089] [Chemical formula]

[0090] [Chemical]

[0091] [Chemical]

[0092] [Other structural units] Examples of other structural units include structural units containing alcoholic hydroxyl groups other than the above structural unit (III), lactone structures, cyclic carbonate structures, sultone structures, or structural units containing combinations thereof.

[0093] When the [A] polymer has other structural units, the upper limit of the content ratio of the other structural units is preferably 20 mol%, more preferably 10 mol%, based on all the structural units constituting the [A] polymer.

[0094] The lower limit of the content ratio of the [A] polymer in the radiation-sensitive resin composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, based on all the components other than the [D] organic solvent in the radiation-sensitive resin composition. The upper limit of the above content ratio is preferably 99% by mass, more preferably 95% by mass.

[0095] [A] As the lower limit of the polystyrene-reduced weight-average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC), 1,000 is preferable, 3,000 is more preferable, 4,000 is further preferable, and 5,000 is particularly preferable. As the upper limit of the above Mw, 50,000 is preferable, 30,000 is more preferable, 20,000 is further preferable, and 10,000 is particularly preferable. [A] By setting the Mw of the polymer within the above range, the coatability of the radiation-sensitive resin composition can be improved, and as a result, the sensitivity, LWR performance, and resolution of the radiation-sensitive resin composition with respect to the exposure light can be further improved.

[0096] [A] As the upper limit of the ratio of Mw to the polystyrene-reduced number-average molecular weight (Mn) of the polymer by GPC (hereinafter, also referred to as "dispersion degree" or "Mw / Mn"), 5 is preferable, 3 is more preferable, 2 is further preferable, and 1.8 is particularly preferable. As the lower limit of the above ratio, it is usually 1.0, and 1.1 is preferable.

[0097] The Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions. GPC column: Two "G2000HXL", one "G3000HXL", and one "G4000HXL" from Tosoh Corporation Column temperature: 40 °C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0098] <[B] Acid generator> [B] The acid generator is a compound represented by the following formula (1-1) or formula (1-2) described later (hereinafter, also referred to as "compound (B1)" or "compound (B2)", and these are collectively referred to as "compound (B)"). Compound (B) is a compound that generates an acid upon irradiation with radiation. Examples of the radiation include the same as those exemplified as the exposure light in the exposure step of the resist pattern forming method described later. When the acid generated from compound (B) dissociates the acid dissociable group (a) contained in the structural unit (II) that the [A] polymer may have, a carboxy group is generated, and a difference in solubility of the resist film in the developer occurs between the exposed portion and the unexposed portion, whereby a resist pattern can be formed.

[0099] The lower limit of the temperature at which the acid generated from compound (B) dissociates the acid dissociable group (a) contained in the structural unit (II) that the [A] polymer may have is preferably 80 °C, more preferably 90 °C, and even more preferably 100 °C. The upper limit of the above temperature is preferably 130 °C, more preferably 120 °C, and even more preferably 110 °C. The lower limit of the time for the acid to dissociate the acid dissociable group (a) is preferably 10 seconds, more preferably 1 minute. The upper limit of the above time is preferably 10 minutes, more preferably 2 minutes.

[0100] In this specification, A in the compound (B) represented by the following formula (1-1) or formula (1-2) - The moiety represented by is referred to as "sulfonic acid anion", and the moiety other than the moiety represented by A - is referred to as "radiation-sensitive onium cation". Among the radiation-sensitive onium cations, the radiation-sensitive onium cation in the following formula (1-1) may be referred to as "radiation-sensitive onium cation (1-1)", and the radiation-sensitive onium cation in the following formula (1-2) may be referred to as "radiation-sensitive onium cation (1-2)".

[0101]

Chemical formula

[0102] In the above formulas (1-1) and (1-2), A - is a monovalent sulfonic acid anion.

[0103] In the above formula (1-1), a is an integer from 0 to 11. b is an integer from 0 to 4. c is an integer from 0 to 4. However, a + b + c is 1 or more. R 1 , R 2 and R 3 are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, at least one of R 1 , R 2 and R 3 is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When a is 2 or more, a plurality of R 1 are the same as or different from each other. When b is 2 or more, a plurality of R 2 are the same as or different from each other. When c is 2 or more, a plurality of R 3 are the same as or different from each other. n1 is 0 or 1. R 4 and R 5 are each independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, or R 4 and R 5 are combined with each other to represent a single bond.

[0104] In the above formula (1-2), d is an integer from 1 to 11. e is an integer from 0 to 10. When d is 1, R 6 is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When d is 2 or more, a plurality of R 6 are the same as or different from each other and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, at least one of the plurality of R 6 is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. R 7 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When e is 2 or more, a plurality of R 7 are the same as or different from each other. R 8represents a single bond or a divalent organic group having 1 to 20 carbon atoms. n2 is 0 or 1. n3 is an integer of 0 to 3.

[0105] R 1 , R 2 , R 3 , R 6 and R 7 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (5) include R 12 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula include the same groups as those exemplified above.

[0106] R 1 , R 2 , R 3 , R 6 and R 7 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0107] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 Examples of the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by the formula (5) include R 13 and R 14 Examples of the fluorinated hydrocarbon group include the same groups as those exemplified as the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by the following formula:

[0108] R 8 Examples of the divalent organic group having 1 to 20 carbon atoms represented by the formula (5) include R 12 Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the following formula (I) include groups in which one hydrogen atom has been removed from the groups exemplified above.

[0109] n1 and n2 are preferably 0 from the viewpoint of further improving the sensitivity to exposure light.

[0110] R 1 , R 2 , R 3 , R6 and R 7 is preferably a fluorine atom or a monovalent perfluoroalkyl group having 1 to 10 carbon atoms, more preferably a fluorine atom or a trifluoromethyl group. Further, from the viewpoint of further improving the sensitivity to exposure light and the LWR performance, the trifluoromethyl group may be preferable to the fluorine atom in some cases.

[0111] a is preferably 0 to 4, more preferably 0 to 3, and still more preferably 0 to 2. b is preferably 0 to 4, more preferably 0 to 3, and still more preferably 0 to 2. c is preferably 0 to 4, more preferably 0 to 3, and still more preferably 0 to 2. a + b + c is preferably 1 to 6, more preferably 1 to 3. Further, in the order of 1, 2, and 3 of a + b + c, the sensitivity to exposure light may be improved in some cases. When a + b + c is 2, it is preferable that a = 0 and b = c = 1. When a + b + c is 3, it is preferable that a = b = c = 1 or a = 3 and b = c = 0. When a + b + c is 4, it is preferable that a = 0 and b = c = 2. When a + b + c is 5, it is preferable that a = 1 and b = c = 2 or a = 5 and b = c = 0. When a + b + c is 6, it is preferable that a = b = c = 2 or a = 0 and b = c = 3. When a + b + c is 7 or more, it is preferable that a, b, and c are all 1 or more.

[0112] R 1 、R 2 and R 3 at least one of is preferably para to the sulfonium cation (S + ).

[0113] R 4 and R 5 is preferably a hydrogen atom or, when combined with each other, represents a single bond.

[0114] As the radiation-sensitive onium cation, the radiation-sensitive onium cation (1-1) is preferable.

[0115] Examples of the radiation-sensitive onium cation (1-1) include radiation-sensitive onium cations represented by the following formulas (1-1-1) to (1-1-14) (hereinafter, also referred to as "radiation-sensitive onium cations (1-1-1) to (1-1-14)").

[0116] [Chemical formula]

[0117] A - The monovalent sulfonate anion represented by is preferably a ring structure. When the sulfonate anion has a ring structure, the LWR performance can be further improved.

[0118] Examples of the above ring structure include an alicyclic structure and an aliphatic heterocyclic structure. Among them, the above ring structure is preferably an adamantane ring structure, a norbornane ring structure or a sultone ring structure, and more preferably a norbornane ring structure.

[0119] Also, A - The monovalent sulfonate anion represented by preferably has a partial structure represented by the following formula (3). When the sulfonate anion has a partial structure represented by the following formula (3), the sensitivity to exposure light, the LWR performance and the resolution can be further improved.

[0120] [Chemical formula]

[0121] In the above formula (3), R 10 and R 11 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. However, at least one of R 10 and R 11 is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. m is an integer of 1 to 10. When m is 2 or more, a plurality of R 10are the same as or different from each other, a plurality of R 11 are the same as or different from each other. * indicates the bonding site with the part other than the structure represented by the formula (3) in the above sulfonate anion.

[0122] R 10 and R 11 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R X and R Y and R Z and R B and R C and R U and R V or R W include groups similar to the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by.

[0123] R 10 and R 11 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R X and R Y and R Z and R B and R C and R U and R V or R W include groups in which at least one hydrogen atom of the groups exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms is substituted with a fluorine atom.

[0124] Furthermore, the sulfonate anion preferably further has a cyclic acetal structure. When the sulfonate anion has a cyclic acetal skeleton, the sensitivity to exposure light and the LWR performance can be further improved.

[0125] Examples of the sulfonate anion include sulfonate anions represented by the following formulas (A1) to (A13) (hereinafter, also referred to as "sulfonate anions (A1) to (A13)").

[0126]

Chemical formula

[0127] As the sulfonic acid anion, sulfonic acid anions (A1) to (A10) or (A13) are preferable, and sulfonic acid anions (A1) to (A5) are more preferable.

[0128] Also, the ring structure of the sulfonic acid anion is preferably an aromatic ring structure substituted with iodine atoms. The above aromatic ring is preferably substituted with 1 to 4 iodine atoms, more preferably substituted with 1 to 3 iodine atoms, and even more preferably substituted with 2 to 3 iodine atoms. As the above aromatic ring, a benzene ring or a naphthalene ring is preferable, and a benzene ring is more preferable.

[0129] Examples of the sulfonic acid anion having an aromatic ring structure substituted with iodine atoms include sulfonic acid anions represented by the following formula.

[0130]

Chemical formula

[0131]

Chemical formula

[0132]

Chemical formula

[0133]

Chemical formula

[0134]

Chemical formula

[0135]

Chemical formula

[0136] Moreover, the ring structure of the sulfonate anion preferably includes a steroid skeleton or a 9,10-ethanoanthracene skeleton.

[0137] The "steroid skeleton" refers to a ring structure represented by the following formula (St) in which three 6-membered rings and one 4-membered ring are condensed.

[0138]

Chemical formula

[0139] The "9,10-ethanoanthracene skeleton" refers to a ring structure represented by the following formula.

[0140]

Chemical formula

[0141] Examples of the sulfonate anion having a steroid skeleton include, for example, the sulfonate anion represented by the following formula. In the following formula, k is an integer of 1 to 5.

[0142]

Chemical formula

[0143] Examples of the sulfonate anion having a 9,10-ethanoanthracene skeleton include, for example, the sulfonate anion represented by the following formula.

[0144]

Chemical formula

[0145] As the lower limit of the content of the [B] acid generator in the radiation-sensitive resin composition, 5 parts by mass is preferable, 10 parts by mass is more preferable, and 15 parts by mass is even more preferable with respect to 100 parts by mass of the [A] polymer. As the upper limit of the above content, 60 parts by mass is preferable, 55 parts by mass is more preferable, and 50 parts by mass is even more preferable. By setting the content of the [B] acid generator within the above range, the sensitivity to exposure light, LWR performance, and resolution can be further improved.

[0146] <[C] acid diffusion control agent> [C] The acid diffusion control agent is a compound represented by the following formula (2) described later (hereinafter, also referred to as "compound (C)"). Compound (C) has the effect of controlling the diffusion phenomenon of the acid generated from the [B] acid generator or the like in the resist film upon exposure and suppressing an undesirable chemical reaction in the unexposed portion.

[0147] [Chemical formula]

[0148] In the above formula (2), R 9 is a monovalent organic group having 1 to 30 carbon atoms. X + is a monovalent radiation-sensitive onium cation.

[0149] R 9Examples of the monovalent organic group having 1 to 30 carbon atoms represented by include a monovalent hydrocarbon group having 1 to 30 carbon atoms, a group containing a divalent heteroatom-containing group between carbon-carbon atoms of the hydrocarbon group (hereinafter also referred to as "group (α')"), a group in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group (hereinafter also referred to as "group (β')"), a group in which some or all of the hydrogen atoms of the group (α') are substituted with a monovalent heteroatom-containing group (hereinafter also referred to as "group (γ')"), and the like. Among them, an aryl group substituted with at least one heteroatom-containing group selected from the group consisting of a hydroxy group, a halogen atom, and a halogenated hydrocarbon group is preferable, and a phenyl group substituted with at least one heteroatom-containing group selected from the group consisting of a hydroxy group, a fluorine atom, an iodine atom, and a trifluoromethyl group is more preferable. Further, a monovalent organic group having 7 to 30 carbon atoms having an aryl group substituted with at least one heteroatom-containing group selected from the group consisting of a hydroxy group, a fluorine atom, an iodine atom, and a trifluoromethyl group is also preferable.

[0150] In the present specification, R in the compound (C) represented by the above formula (2) 9 -COO - The moiety represented by is referred to as "anion of weak acid", and X + The moiety represented by is referred to as "radiation-sensitive onium cation".

[0151] Examples of the anion of weak acid include anions represented by the following formulas (C1) to (C5) and the like.

[0152]

Chemical formula

[0153] Examples of the radiation-sensitive onium cation include a triphenylsulfonium cation, a phenyldibenzothiophenium cation, a 1-naphthyldiphenylsulfonium cation, a 2-naphthyldiphenylsulfonium cation, the radiation-sensitive onium cation in the above formula (1-1), the radiation-sensitive onium cation in the above formula (1-2), and the like.

[0154] As the compound (C), a compound obtained by appropriately combining the anion of the above weak acid and the above radiation-sensitive onium cation can be used.

[0155] As the lower limit of the content ratio of the [C] acid diffusion control agent in the radiation-sensitive resin composition, 1 mol% is preferable, 5 mol% is more preferable, and 10 mol% is even more preferable with respect to 100 mol% of the [B] acid generator. As the upper limit of the above content, 100 mol% is preferable, 50 mol% is more preferable, and 30 mol% is even more preferable. By setting the content ratio of the [C] acid diffusion control agent within the above range, the sensitivity to exposure light, LWR performance, and resolution of the resist pattern formed by the radiation-sensitive resin composition can be further improved.

[0156] <[D] Organic Solvent> The radiation-sensitive resin composition usually contains a [D] organic solvent. The [D] organic solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, [B] acid generator, and [C] acid diffusion control agent, and other optional components contained as necessary.

[0157] Examples of the [D] organic solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, etc. The [D] organic solvent can contain one or more kinds.

[0158] Examples of the alcohol solvent include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol, alicyclic monoalcohol solvents having 3 to 18 carbon atoms such as cyclohexanol, polyhydric alcohol solvents having 2 to 18 carbon atoms such as 1,2-propylene glycol, and polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms such as propylene glycol-1-methyl ether.

[0159] Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0160] Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0161] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0162] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; lactone solvents such as γ-butyrolactone and valerolactone; polyhydric alcohol carboxylate solvents such as propylene glycol acetate; polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate; polycarboxylic acid diester solvents such as diethyl oxalate; and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

[0163] Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms such as n-pentane and n-hexane, and aromatic hydrocarbon solvents having 6 to 16 carbon atoms such as toluene and xylene.

[0164] [D] As the organic solvent, an alcohol solvent and / or an ester solvent are preferable, a polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms and / or a polyhydric alcohol partial ether carboxylate solvent are more preferable, and propylene glycol-1-monomethyl ether and / or propylene glycol monomethyl ether acetate are even more preferable.

[0165] When the radiation-sensitive resin composition contains [D] an organic solvent, the lower limit of the content ratio of [D] the organic solvent is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and particularly preferably 80% by mass with respect to all the components contained in the radiation-sensitive resin composition. The upper limit of the above content ratio is preferably 99.9% by mass, preferably 99.5% by mass, and even more preferably 99.0% by mass.

[0166] <Other optional components> Examples of other optional components include surfactants. The radiation-sensitive resin composition may contain each of the other optional components in one kind or two or more kinds.

[0167] <Resist pattern forming method> The resist pattern forming method includes a step of coating a radiation-sensitive resin composition directly or indirectly on a substrate (hereinafter, also referred to as "coating step"), a step of exposing the resist film formed by the above coating step (hereinafter, also referred to as "exposure step"), and a step of developing the exposed resist film (hereinafter, also referred to as "development step").

[0168] According to the resist pattern forming method, by using the above-described radiation-sensitive resin composition as the radiation-sensitive resin composition in the coating step, a resist pattern having good sensitivity to exposure light and excellent LWR performance and resolution can be formed.

[0169] Hereinafter, each step included in the resist pattern forming method will be described.

[0170] [Coating Step] In this step, the radiation-sensitive resin composition is coated directly or indirectly on the substrate. Thereby, a resist film is formed directly or indirectly on the substrate.

[0171] In this step, the above-described radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

[0172] Examples of the substrate include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, as a case where the radiation-sensitive resin composition is coated indirectly on the substrate, for example, a case where the radiation-sensitive resin composition is coated on an antireflection film formed on the substrate can be mentioned. Examples of such an antireflection film include organic or inorganic antireflection films disclosed in, for example, Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448.

[0173] Examples of the coating method include spin coating, casting, roll coating, etc. After coating, if necessary, prebaking (hereinafter also referred to as "PB") may be performed to volatilize the solvent in the coating film. The lower limit of the PB temperature is preferably 60°C, more preferably 80°C. The upper limit of the above temperature is preferably 150°C, more preferably 140°C. The lower limit of the PB time is preferably 5 seconds, more preferably 10 seconds. The lower limit of the above time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the formed resist film is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[0174] [Exposure process] In this process, the resist film formed in the above coating process is exposed. This exposure is performed by irradiating exposure light through a photomask (in some cases, through an immersion medium such as water). Examples of the exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and γ-rays; charged particle beams such as electron beams and α-rays. Among these, far ultraviolet light, EUV, or electron beams are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beams are more preferred, ArF excimer laser light, EUV, or electron beams are even more preferred, and EUV or electron beams are particularly preferred.

[0175] After the above exposure, post-exposure baking (hereinafter also referred to as "PEB") is performed. In the exposed portion of the resist film, it is preferable to promote the dissociation of the acid-labile groups of [A] polymers, etc. by the acid generated from [B] acid generators, etc. due to the exposure. By this PEB, the difference in solubility in the developer between the exposed portion and the unexposed portion can be increased. The lower limit of the temperature of PEB is preferably 50°C, more preferably 80°C, and even more preferably 100°C. The upper limit of the above temperature is preferably 180°C, more preferably 130°C. The lower limit of the time of PEB is preferably 5 seconds, more preferably 10 seconds, and even more preferably 30 seconds. The upper limit of the above time is preferably 600 seconds, more preferably 300 seconds, and even more preferably 100 seconds.

[0176] [Development process] In this process, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse liquid such as water or alcohol and then dry. The development method in the development process may be either alkali development or organic solvent development.

[0177] In the case of alkaline development, examples of the developer used for 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 (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. Among these, an aqueous TMAH solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

[0178] In the case of organic solvent development, examples of the developer include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents and other organic solvents, solutions containing the above organic solvents, and the like. Examples of the above organic solvents include one or more of the solvents exemplified as the [D] organic solvent of the above radiation-sensitive resin composition. Among these, ester solvents or ketone solvents are preferable. As the ester solvent, an acetic acid ester solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The lower limit of the content of the organic solvent in the developer is preferably 80% by mass, more preferably 90% by mass, further preferably 95% by mass, and particularly preferably 99% by mass. Examples of the components other than the organic solvent in the developer include water, silicone oil and the like.

[0179] Examples of the development method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by raising the developer on the substrate surface by surface tension and allowing it to stand for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning a developer discharge nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method), and the like.

[0180] Examples of patterns formed by the resist pattern forming method include, for example, line and space patterns, hole patterns, and the like.

Examples

[0181] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The physical property values in the examples were measured as follows.

[0182] [Weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn)] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were measured by gel permeation chromatography (GPC) using Tosoh Corporation GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Also, the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn. Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Column temperature: 40 °C Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0183] [Content ratio of structural units] The content ratio of each structural unit in the polymer was measured by 13C-NMR analysis using a nuclear magnetic resonance apparatus ("JNM-Delta400" manufactured by JEOL Ltd.). 13

[0184] <[Synthesis of polymer]> Monomers represented by the following formulae (M-1) to (M-11) (hereinafter also referred to as "monomers (M-1) to (M-11)") were used in the synthesis of polymer [A]. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value where the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value where the total number of moles of the monomers used is taken as 100 mol %.

[0185] [ka]

[0186] [Synthesis Example 1] Synthesis of polymer (A-1) Monomer (M-1) and monomer (M-3) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio was 40 / 60. Next, 6 mol% of azobisisobutyronitrile was added as an initiator to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for another 3 hours, allowing the polymerization reaction to proceed for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

[0187] 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 hexane (100 parts by mass relative to the polymerization solution), then filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After completion of the hydrolysis reaction, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). The resin was dropped into 500 parts by mass of water to coagulate, and the resulting solid was filtered off. The resulting mixture was dried at 50°C for 12 hours to obtain a white powdery polymer (A-1).

[0188] The Mw of the polymer (A-1) was 5,700, and the Mw / Mn was 1.61. 13As a result of the 13C-NMR analysis, the content ratios of the respective structural units derived from monomer (M-1) and monomer (M-3) in polymer (A-1) were 41.2 mol% and 58.8 mol%, respectively.

[0189] [Synthesis Examples 2 to 9] Synthesis of Polymers (A-2) to (A-9) Polymers (A-2) to (A-9) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and usage ratios shown in Table 1 below were used.

[0190]

Table 1

[0191] <[Synthesis of Acid Generator]> [Synthesis Example 10] Synthesis of Acid Generator (B-1) 40.3 mmol of bis(4-fluorophenyl)sulfoxide and 290 g of tetrahydrofuran were added to a reaction vessel. After stirring at 0 °C, 121 mmol of chlorotrimethylsilane was added dropwise. Subsequently, 121 mmol of 4-fluorophenylmagnesium bromide was added dropwise. After stirring at room temperature for 1 hour, a 2M aqueous hydrochloric acid solution was added, and then the aqueous layer was separated. The obtained aqueous layer was washed with diethyl ether, and the organic layer was extracted with dichloromethane. After drying over sodium sulfate, the solvent was distilled off, and purification by column chromatography gave a compound represented by the following formula (S-1) (hereinafter also referred to as "bromide salt (S-1)").

[0192] 20.0 mmol of the bromide salt (S-1) obtained above, 20.0 mmol of an ammonium salt represented by the following formula (P-1), 150 g of dichloromethane, and 150 g of ultrapure water were added to the reaction solution. After stirring at room temperature for 2 hours, the organic layer was separated. The obtained organic layer was washed with ultrapure water. After drying over sodium sulfate, the solvent was distilled off, and purification by column chromatography gave a compound represented by the following formula (B-1) (hereinafter also referred to as "acid generator (B-1)").

[0193] The synthesis scheme of acid generator (B-1) is shown below.

[0194] [Chemical formula]

[0195] [Synthesis Examples 11 to 34] Synthesis of Acid Generators (B-2) to (B-25) Compounds represented by the following formulas (B-2) to (B-25) (hereinafter also referred to as "acid generators (B-2) to (B-25)") were synthesized in the same manner as in Synthesis Example 10, except that the precursors were appropriately selected.

[0196] [Chemical formula]

[0197] [Chemical formula]

[0198] [Preparation of Radiation-Sensitive Resin Composition] The acid diffusion control agent [C] and the organic solvent [D] used in the preparation of the radiation-sensitive resin composition are shown below. In the following examples and comparative examples, unless otherwise specified, parts by mass mean the values when the mass of the used [A] polymer is 100 parts by mass, and mol% means the values when the number of moles of the used [B] acid generator is 100 mol%.

[0199] [[C] Acid Diffusion Control Agent] (C-1) to (C-10): Compounds represented by the following formulas (C-1) to (C-10)

[0200] [Chemical formula]

[0201] [[D] Organic Solvent] (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol-1-monomethyl ether

[0202] [Example 1] Preparation of Radiation-Sensitive Resin Composition (R-1) 100 parts by mass of (A-1) as a polymer, 20 parts by mass of (B-1) as an acid generator, 20 mol% of (C-1) as an acid diffusion controller with respect to 100 mol% of (B-1), and 4,800 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as organic solvents were mixed to prepare a radiation-sensitive resin composition (R-1).

[0203] [Examples 2 to 39 and Comparative Examples 1 to 15] Preparation of Radiation-Sensitive Resin Compositions (R-2) to (R-39) and (CR-1) to (CR-15) Radiation-sensitive resin compositions (R-2) to (R-39) and (CR-1) to (CR-15) were prepared in the same manner as in Example 1, except that the components of the types and contents shown in Table 2 below were used.

[0204] [Table 2]

[0205] [Formation of Resist Pattern] On the surface of a 12-inch silicon wafer on which an underlayer film (Brewer Science's "AL412") with an average thickness of 20 nm was formed, each of the above-prepared radiation-sensitive resin compositions was coated using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), and after soft baking (SB) at 130°C for 60 seconds, it was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 50 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine ("NXE3300" manufactured by ASML, NA = 0.33, illumination condition: Conventional s = 0.89, mask imecDEFECT32FFR02). After irradiation, post-exposure baking (PEB) was performed on the resist film at 130°C for 60 seconds. Then, using a 2.38 mass% TMAH aqueous solution, development was carried out at 23°C for 30 seconds to form a positive resist pattern (32 nm line and space pattern).

[0206] [Evaluation] For each of the formed resist patterns, the sensitivity, LWR performance, and resolution of each radiation-sensitive resin composition were evaluated according to the following method. A scanning electron microscope ("CG-4100" of Hitachi High-Technologies Corporation) was used for measuring the length of the resist pattern. The evaluation results are shown in Table 3 below.

[0207] [Sensitivity] In the formation of the above resist pattern, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was designated as Eop (unit: mJ / cm 2 ). Sensitivity can be evaluated as "good" when Eop is 30 mJ / cm 2 or less, and as "bad" when it exceeds 30 mJ / cm 2 .

[0208] [LWR Performance] The resist pattern was observed from above using the above scanning electron microscope. The line width was measured at 50 arbitrary points, and the 3-sigma value was obtained from the distribution of the measured values and designated as LWR (unit: nm). The smaller the value of LWR, the smaller the line wobbling, indicating good performance. LWR performance can be evaluated as "good" when LWR is 4.0 nm or less, and as "bad" when it exceeds 4.0 nm.

[0209] [Resolution] At the above optimum exposure dose, when the size of the mask pattern for forming a line and space (1L / 1S) was changed, the dimension of the smallest resist pattern that could be resolved was measured, and this measured value was designated as the resolution (unit: nm). The smaller the value of the resolution, the finer the pattern that can be formed, indicating good performance. Resolution can be evaluated as "good" when the resolution is 25 nm or less, and as "bad" when it exceeds 25 nm.

[0210]

Table 3

[0211] As is clear from the results in Table 3, all of the radiation-sensitive resin compositions of the examples were superior in sensitivity, LWR performance, and resolution to the radiation-sensitive resin compositions of the comparative examples.

[0212] [Example 40] Preparation of Radiation-Sensitive Resin Composition (R-40) A radiation-sensitive resin composition (R-40) was prepared in the same manner as in Example 1, except that the compound represented by the following formula (acid generator (B-26)) was used instead of the acid generator (B-1). Subsequently, a resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-40) was superior in sensitivity, LWR performance, and resolution to the radiation-sensitive resin compositions of the comparative examples.

[0213] [Chemical formula]

[0214] [Example 41] Preparation of Radiation-Sensitive Resin Composition (R-41) A radiation-sensitive resin composition (R-41) was prepared in the same manner as in Example 1, except that the compound represented by the following formula (acid generator (B-27)) was used instead of the acid generator (B-1). Subsequently, a resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-41) was superior in sensitivity, LWR performance, and resolution to the radiation-sensitive resin compositions of the comparative examples.

[0215] [Chemical formula]

[0216] [Example 42] Preparation of Radiation-Sensitive Resin Composition (R-42) A radiation-sensitive resin composition (R-42) was prepared in the same manner as in Example 1, except that the compound represented by the following formula (acid generator (B-28)) was used instead of the acid generator (B-1). Then, a resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-42) had good sensitivity, LWR performance, and resolution compared to the radiation-sensitive resin composition of the comparative example.

[0217] [Chemical formula]

[0218] [Example 43] Preparation of radiation-sensitive resin composition (R-43) A polymer (A-10) was synthesized in the same manner as in Synthesis Example 4, except that the monomer represented by the following formula (monomer (M-12)) was used instead of the monomer (M-6). Then, a radiation-sensitive resin composition (R-43) was prepared in the same manner as in Example 34, except that the polymer (A-10) was used instead of the polymer (A-4). A resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-43) had good sensitivity, LWR performance, and resolution compared to the radiation-sensitive resin composition of the comparative example.

[0219] [Chemical formula]

[0220] [Example 44] Preparation of radiation-sensitive resin composition (R-44) A polymer (A-11) was synthesized in the same manner as in Synthesis Example 2, except that a monomer (monomer (M-13)) represented by the following formula was used instead of the monomer (M-4). Next, a radiation-sensitive resin composition (R-44) was prepared in the same manner as in Example 32, except that the polymer (A-11) was used instead of the polymer (A-2). A resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-44) had good sensitivity, LWR performance, and resolution compared to the radiation-sensitive resin composition of the comparative example.

[0221] [Chemical formula]

[0222] [Example 45] Preparation of Radiation-Sensitive Resin Composition (R-45) A polymer (A-12) was synthesized in the same manner as in Synthesis Example 4, except that a monomer (monomer (M-14)) represented by the following formula was used instead of the monomer (M-6). Next, a radiation-sensitive resin composition (R-45) was prepared in the same manner as in Example 34, except that the polymer (A-12) was used instead of the polymer (A-4). A resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-45) had good sensitivity, LWR performance, and resolution compared to the radiation-sensitive resin composition of the comparative example.

[0223] [Chemical formula]

[0224] [Example 46] Preparation of Radiation-Sensitive Resin Composition (R-46) A polymer (A-13) was synthesized in the same manner as in Synthesis Example 1, except that the monomer (M-1), monomer (M-3), and monomer (monomer (M-15)) represented by the following formula were used so that the molar ratio was 30 / 55 / 15. Subsequently, a radiation-sensitive resin composition (R-46) was prepared in the same manner as in Example 1, except that the polymer (A-13) was used instead of the polymer (A-1). A resist pattern was formed in the same manner as above, and the sensitivity, LWR performance, and resolution were evaluated. As a result, the radiation-sensitive resin composition (R-46) had good sensitivity, LWR performance, and resolution as compared with the radiation-sensitive resin composition of the comparative example.

[0225]

Chemical formula

Industrial Applicability

[0226] According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern having good sensitivity to exposure light, excellent LWR performance, and resolution can be formed. Therefore, it can be suitably used for forming a fine resist pattern in a lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A polymer having a first structural unit containing a phenolic hydroxyl group, a compound represented by the following formula (1-1) or formula (1-2), and a compound represented by the following formula (2) A radiation-sensitive resin composition containing the same. 【Chemical 1】 (In formulas (1-1) and (1-2), A － is a monovalent sulfonic acid anion.) In formula (1-1), a is an integer from 0 to 11. b is an integer from 0 to 4. c is an integer from 0 to 4. However, a + b + c is 1 or more. R １ , R ２ and R ３ are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, R １ , R ２ and R ３ Among them, at least one is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When a is 2 or more, the plurality of R １ are the same as or different from each other. When b is 2 or more, the plurality of R ２ are the same as or different from each other. When c is 2 or more, a plurality of Rs ３ are the same as or different from each other. n １ is 0 or 1. R ４ and R ５ are each independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, or R ４ and R ５ are combined with each other to represent a single bond. In formula (1-2), d is an integer from 1 to 11. e is an integer from 0 to 10. When d is 1, R ６ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When d is 2 or more, a plurality of R ６ are the same as or different from each other, and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, at least one of the plurality of R ６ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. R ７ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When e is 2 or more, a plurality of R ７ are the same as or different from each other. R ８ is a single bond or a divalent organic group having 1 to 20 carbon atoms. n ２ is 0 or 1. n ３ is an integer from 0 to 3.) 【Chemical Formula 2】 (In formula (2), R ９ is a monovalent organic group having 1 to 30 carbon atoms. X ＋ is a monovalent radiation-sensitive onium cation.)

2. The radiation-sensitive resin composition according to claim 1, wherein the sulfonic acid anion has a ring structure.

3. The radiation-sensitive resin composition according to claim 2, wherein the ring structure is at least one selected from a norbornane structure, an adamantane structure, and a sultone structure.

4. The radiation-sensitive resin composition according to claim 1, claim 2, or claim 3, wherein the sulfonic acid anion has a partial structure represented by the following formula (3). [Chemical Formula 3] (In formula (3), R １０ and R １１ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. However, at least one of R １０ and R １１ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. m is an integer of 1 to 10. When m is 2 or more, the plurality of R １０ are the same as or different from each other, and the plurality of R １１ are the same as or different from each other. * indicates the bonding site with the portion other than the structure represented by formula (3) in the above sulfonate anion.)

5. The radiation-sensitive resin composition according to claim 2, wherein the ring structure is an aromatic ring structure substituted with an iodine atom.

6. The radiation-sensitive resin composition according to claim 2, wherein the ring structure contains a steroid skeleton or a 9,10-ethanoanthracene skeleton.

7. The radiation-sensitive resin composition according to any one of claims 1 to 6, wherein the polymer further has a second structural unit containing an acid dissociable group that dissociates by the action of an acid to give a carboxy group.

8. The radiation-sensitive resin composition according to claim 7, wherein the second structural unit is represented by the following formula (4-1), (4-2), or (4-3). 【Chemical Formula 4】 (In formulas (4-1), (4-2) and (4-3), R Ｔ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.) In formula (4-1), R Ｘ is, independently of one another, a monovalent hydrocarbon group having 1 to 20 carbon atoms. R Ｙ and R Ｚ are, independently of one another, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a part of an alicyclic structure having 3 to 20 ring members formed by combining these groups together with the carbon atom to which they are attached. In formula (4-2), R Ａ is a hydrogen atom. R Ｂ and R Ｃ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R Ｄ is a divalent hydrocarbon group having 1 to 20 carbon atoms which, together with the carbon atom to which R Ａ , R Ｂ and R Ｃ are each attached, forms an unsaturated alicyclic structure having 4 to 20 ring members. In formula (4-3), R Ｕ and R Ｖ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R Ｗ is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ｕ and R Ｖ are combined with each other to form part of an alicyclic structure having 3 to 20 ring members together with the carbon atom to which they are attached, or R Ｕ and R Ｗ are combined with each other and form part of an aliphatic heterocyclic structure having 5 to 20 ring members together with the carbon atom to which R Ｕ is attached and the oxygen atom to which R Ｗ is attached. )

9. In the above formula (4-1), R Ｘ is an alkyl group, an ethenyl group or a phenyl group, and R Ｙ and R Ｚ are combined with each other and are part of an alicyclic structure having 3 to 20 ring members formed together with the carbon atoms to which they are attached. The radiation-sensitive resin composition according to claim 8.

10. The radiation-sensitive resin composition according to claim 9, wherein the alicyclic structure contains a norbornane skeleton.

11. The radiation-sensitive resin composition according to any one of claims 7 to 10, wherein in the second structural unit, the acid dissociable group is separated from the polymer main chain by at least 5 atoms in terms of the number of atoms.

12. The radiation-sensitive resin composition according to any one of claims 1 to 11, wherein the polymer further has a third structural unit containing a partial structure represented by the following formula (5). 【Chemical Formula 5】 (In formula (5), R １２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R １３ and R １４ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. ** indicates a bonding site with a portion other than the partial structure represented by formula (5) in the above third structural unit.)

13. The radiation-sensitive resin composition according to any one of claims 1 to 12, wherein the polymer further has a fourth structural unit containing a partial structure that generates sulfonic acid upon exposure.

14. A step of coating a radiation-sensitive resin composition directly or indirectly on a substrate, a step of exposing the resist film formed by the coating step, and a step of developing the exposed resist film comprising: wherein the radiation-sensitive resin composition contains a polymer having a first structural unit containing a phenolic hydroxyl group, a compound represented by the following formula (1-1) or (1-2), and a compound represented by the following formula (2) A resist pattern forming method containing 【Chemical Formula 6】 (In formulas (1-1) and (1-2), A － is a monovalent sulfonic acid anion.) In formula (1-1), a is an integer from 0 to 11. b is an integer from 0 to 4. c is an integer from 0 to 4. However, a + b + c is 1 or more. R １ , R ２ and R ３ are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, at least one of R １ , R ２ and R ３ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When a is 2 or more, a plurality of R １ are the same as or different from each other. When b is 2 or more, a plurality of R ２ are the same as or different from each other. When c is 2 or more, a plurality of Rs ３ are the same as or different from each other. n １ is 0 or 1. R ４ and R ５ are each independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, or R ４ and R ５ are a single bond combined with each other. In formula (1-2), d is an integer from 1 to 11. e is an integer from 0 to 10. When d is 1, R ６ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. When d is 2 or more, a plurality of R ６ are the same as or different from each other and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. However, at least one of the plurality of R ６ is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. R ７ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When e is 2 or more, a plurality of R ７ are the same as or different from each other. R ８ is a single bond or a divalent organic group having 1 to 20 carbon atoms. n ２ is 0 or 1. n ３ is an integer from 0 to 3.) 【Chemical Formula 7】 (In formula (2), R ９ is a monovalent organic group having 1 to 30 carbon atoms. X ＋ is a monovalent radiation-sensitive onium cation.)

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