Radiation-sensitive resin composition and method for forming a resist pattern

Abstract

Provided is a radiation-sensitive resin composition comprising: a polymer which has a first structural unit represented by formula (1) and of which the solubility in a developing solution is changed by the action of an acid; a radiation-sensitive acid generator; and an acid diffusion regulator which has a monovalent radiation-sensitive onium cation and a monovalent organic acid anion.

Description

[Technical Field]

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

[0002] Radiation-sensitive resin compositions used in microfabrication by lithography generate acid in the exposed areas when irradiated with radiation such as far-ultraviolet light (ArF excimer laser light, wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet light (EUV) (wavelength 13.5 nm), and charged particle beams such as electron beams. A chemical reaction catalyzed by this acid causes a difference in the dissolution rate in the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] Radiation-sensitive resin compositions are required to have good sensitivity to exposure light such as extreme ultraviolet light and electron beams, as well as excellent LWR (Line Width Roughness) performance. Furthermore, with the further miniaturization of resist patterns, even slight variations in exposure and development conditions have an increasingly significant impact on the shape of the resist pattern and the occurrence of defects. Therefore, there is a need for radiation-sensitive resin compositions with a wide process window (process margin) that can absorb such slight variations in process conditions.

[0004] In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive resin compositions have been investigated, and their combinations have also been studied in detail (see Japanese Patent Publication Nos. 2010-134279, 2014-224984, and 2016-047815). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-134279 [Patent Document 2] Japanese Patent Publication No. 2014-224984 [Patent Document 3] Japanese Patent Publication No. 2016-047815 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] As resist patterns become even finer, the required performance levels are increasing, and there is a need for radiation-sensitive resin compositions that can meet these requirements.

[0007] The present invention has been made based on the circumstances described above, and its objective is to provide a radiation-sensitive resin composition and a resist pattern formation method that exhibit excellent sensitivity and LWR performance and have a wide process window. [Means for solving the problem]

[0008] The invention made to solve the above problems is a radiation-sensitive resin composition containing a polymer having a first structural unit represented by the following formula (1) and whose solubility in a developer changes upon the action of an acid (hereinafter also referred to as "[A] polymer"), a radiation-sensitive acid generator (hereinafter also referred to as "[B] acid generator"), and an acid diffusion control agent having a monovalent radiation-sensitive onium cation and a monovalent organic acid anion (hereinafter also referred to as "[C] acid diffusion control agent". [ka] (In formula (1), R 1 L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 Ar is a single bond or a divalent linking group. 1 (This refers to a group obtained by removing one hydrogen atom from a substituted or unsubstituted condensed polycyclic aromatic hydrocarbon ring with 13 or more members.)

[0009] Another invention made to solve the above problems is a resist pattern forming method comprising the steps of directly or indirectly coating a substrate with the above-mentioned radiation-sensitive resin composition, exposing the resist film formed by the coating, and developing the exposed resist film. [Effects of the Invention]

[0010] The radiation-sensitive resin composition of the present invention exhibits excellent sensitivity and LWR performance, and has a wide process window. The resist pattern formation method of the present invention enables the formation of resist patterns with excellent sensitivity and LWR performance, and a wide process window. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected. [Modes for carrying out the invention]

[0011] The radiation-sensitive resin composition and resist pattern formation method of the present invention will be described in detail below.

[0012] <Radiation sensitive resin composition> The radiation-sensitive resin composition contains [A] a polymer, [B] an acid generator, and [C] an acid diffusion control agent. The radiation-sensitive resin composition typically 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 they do not impair the effects of the present invention.

[0013] The radiation-sensitive resin composition contains [A] polymer, [B] acid generator, and [C] acid diffusion control agent, resulting in excellent sensitivity and LWR performance, as well as a wide process window. The reason why the radiation-sensitive resin composition achieves the above effects through the above configuration is not entirely clear, but it can be inferred, for example, as follows: It is thought that the [A] polymer has a first structural unit represented by formula (1) described below, which increases the amount of acid generated from the [B] acid generator etc. upon exposure. And, as the amount of acid generated from the [B] acid generator etc. increases, it is thought that the change in solubility in the developer increases due to the action of the acid possessed by the [A] polymer. As a result, it is thought that the above effects are achieved.

[0014] The radiation-sensitive resin composition can be prepared by mixing, for example, a polymer, an acid generator, and an acid diffusion control agent in predetermined proportions, and optionally, an organic solvent and other optional components, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.20 μm or less.

[0015] The following describes each component contained in the radiation-sensitive resin composition.

[0016] <[A] Polymer> [A] polymers have a first structural unit (hereinafter also referred to as "structural unit (I)") represented by formula (1) described below. [A] polymers are polymers whose solubility in a developer changes upon the action of an acid. The radiation-sensitive resin composition may contain one or more [A] polymers.

[0017] [A] The polymer preferably further has a second structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (II)"). [A] The polymer preferably further has a third structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (III)"). [A] The polymer may further have other structural units other than structural units (I) to (III) (hereinafter simply referred to as "other structural units"). [A] The polymer may have one or more of each structural unit.

[0018] Furthermore, the structural units of polymer [A] may be considered to belong to two or more classifications of structural units. For example, a structural unit may be considered to belong not only to structural unit (I) but also to structural units other than structural unit (I). In such cases, this specification will treat the structural unit as belonging to the one with the lower number in parentheses.

[0019] The lower limit of the content 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, relative to all components other than the [D] organic solvent contained in the radiation-sensitive resin composition. The upper limit of the above content is preferably 99% by mass, and more preferably 95% by mass.

[0020] [A] The lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) of the polymer determined by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, even more preferably 3,000, and even more preferably 4,000. The upper limit of the above Mw is preferably 30,000, more preferably 20,000, even more preferably 19,000, and even more preferably 17,000. [A] By setting the Mw of the polymer within the above range, the coating properties of the radiation-sensitive resin composition can be improved. [A] The Mw of the polymer can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in synthesis.

[0021] [A] The upper limit of the ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the polymer by GPC (hereinafter also referred to as "Mw / Mn" or "polydispersity") is preferably 2.5, more preferably 2.0, even more preferably 1.9, and even more preferably 1.7. The lower limit of the above ratio is usually 1.0, preferably 1.1, more preferably 1.2, even more preferably 1.3, and even more preferably 1.4.

[0022] [Methods for measuring Mw and Mn] In this specification, the Mw and Mn values ​​of the [A] polymer are measured using gel permeation chromatography (GPC) under the following conditions. GPC columns: Two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column from Tosoh Corporation. Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0023] [A] Polymers can be synthesized, for example, by polymerizing monomers that give each structural unit using known methods.

[0024] The following describes the various structural units of polymer [A].

[0025] [Structural Unit (I)] A structural unit (I) is a structural unit represented by the following formula (1).

[0026] [ka]

[0027] In the above equation (1), R 1 L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1is a single bond or a divalent linking group. Ar 1 is a group obtained by removing one hydrogen atom from a substituted or unsubstituted condensed polycyclic aromatic hydrocarbon ring having 13 or more ring members.

[0028] "The number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycyclic ring, it refers to the number of atoms constituting this polycyclic ring. "Condensed polycycle" means a ring structure in which two adjacent rings have two shared atoms. "Condensed polycycle" is clearly distinguished from "ring-assembled polycycle" in which two adjacent rings do not have shared atoms and are connected by single bonds. "A group obtained by removing X hydrogen atoms from a ring structure" means a group obtained by removing X hydrogen atoms bonded to the atoms constituting the ring structure.

[0029] R 1 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 methyl group is more preferable.

[0030] L 1 Examples of the divalent linking group in L include a carbonyl group, an ether group, a sulfide group, an alkanediyl group having 1 to 10 carbon atoms, or a group combining these. L 1 When L is a divalent linking group, L 1 The shortest number of atomic chains between the oxygen atom to which L 1 is bonded and Ar is preferably 1 to 4.

[0031] L 1 From the viewpoint of further widening the process window of the radiation-sensitive resin composition, it is preferably a single bond. Also, from the viewpoint of further increasing the sensitivity of the radiation-sensitive resin composition, it is preferably a divalent linking group.

[0032] Ar 1Examples of condensed polycyclic aromatic hydrocarbon rings with 13 or more members that give the property include condensed tricyclic aromatic hydrocarbon rings such as anthracene rings (14 members), phenanthrene rings (14 members), and phenalene rings (13 members); condensed tetracyclic aromatic hydrocarbon rings such as pyrene rings (16 members), chrysene rings (18 members), tetrafene rings (18 members), tetracene rings (18 members), and triphenylene rings (18 members); and condensed pentacyclic aromatic hydrocarbon rings such as perylene rings (20 members), picene rings (22 members), pentaphene rings (22 members), and pentacene rings (22 members).

[0033] The lower limit of the number of ring members in the above-mentioned condensed polycyclic aromatic hydrocarbon ring is 13, with 14 being preferred. The upper limit of the number of ring members is preferably 22, more preferably 20, even more preferably 18, and even more preferably 16.

[0034] The above-mentioned condensed polycyclic aromatic hydrocarbon ring is preferably a condensed tricyclic aromatic hydrocarbon ring or a condensed tetracyclic aromatic hydrocarbon ring, more preferably an anthracene ring, a phenanthrene ring, or a pyrene ring, even more preferably an anthracene ring or a pyrene ring, and even more preferably a pyrene ring. When it is an anthracene ring or a pyrene ring, it is preferred over a phenanthrene ring because the sensitivity, LWR performance, and process window of the radiation-sensitive resin composition are superior. Furthermore, when it is a pyrene ring, it is preferred over an anthracene ring because the sensitivity and process window of the radiation-sensitive resin composition are even superior.

[0035] Substituents that the above-mentioned condensed polycyclic aromatic hydrocarbon ring may have include, for example, halogen atoms such as fluorine, chlorine, bromine, and iodine, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. From the viewpoint of further improving the LWR performance of the radiation-sensitive resin composition, it is preferable that the above-mentioned condensed polycyclic aromatic hydrocarbon ring is a substituted condensed polycyclic aromatic hydrocarbon ring. In this case, halogen atoms are preferred as substituents, bromine atoms or iodine atoms are more preferred, and iodine atoms are even more preferred. On the other hand, from the viewpoint of further broadening the process window of the radiation-sensitive resin composition, it is preferable that the above-mentioned condensed polycyclic aromatic hydrocarbon ring is an unsubstituted condensed polycyclic aromatic hydrocarbon ring.

[0036] [A] The lower limit of the content of structural unit (I) in polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 20 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 70 mol%, more preferably 60 mol%, and even more preferably 50 mol%. By setting the content of structural unit (I) within the above range, the sensitivity, LWR performance, and process window of the radiation-sensitive resin composition can be further improved or a good balance can be achieved. Unless otherwise specified, the upper limit of numerical ranges in this specification may be "less than or equal to" or "less than", and the lower limit may be "greater than or equal to" or "greater than". Furthermore, the upper and lower limits can be combined arbitrarily.

[0037] A polymer having structural unit (I) can be synthesized by polymerizing a monomer that gives structural unit (I) (hereinafter also referred to as "[X] monomer") by a known method. The [X] monomer is, for example, 9-antrol, which is the Ar in formula (1) above. 1 This can be obtained by reacting a compound that gives [X] with a compound that forms the backbone structure of the [X] monomer, such as methacryloyl chloride, using a known method.

[0038] [Structural Units (II)] Structural unit (II) is a structural unit containing an acid-dissociable group. An "acid-dissociable group" is a group that substitutes a hydrogen atom in a carboxyl group, hydroxyl group, etc., and dissociates upon the action of an acid to give a carboxyl group, hydroxyl group, etc. Upon exposure, the acid-dissociable group dissociates due to the action of the acid generated from the [B] acid generator, etc., and a difference in the solubility of the [A] polymer in the developer between the exposed and unexposed areas is created, thereby forming a resist pattern. Typically, the [A] polymer exhibits the property of changing its solubility in the developer upon the action of an acid because it contains structural unit (II).

[0039] Examples of structural units (II) include structural units represented by the following formulas (II-1) or (II-2) (hereinafter also referred to as "structural unit (II-1) or (II-2)"). For example, in the following formula (II-1), -C(R X )(R Y )(R Z ) corresponds to an acid-dissociable group.

[0040] [ka]

[0041] In the above equations (II-1) and (II-2), R T These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0042] In the above equation (II-1), R X R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Y and R Z Each of these groups is either an independent monovalent hydrocarbon group having 1 to 20 carbon atoms, or a part of a saturated alicyclic ring with 3 to 20 members, formed by combining these groups with the carbon atoms to which they are bonded.

[0043] In the above equation (II-2), R A R is a hydrogen atom.B and R C Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. D R A , R B and R C These are divalent hydrocarbon groups with 1 to 20 carbon atoms that, together with the carbon atoms to which they are bonded, constitute an unsaturated alicyclic ring with 4 to 20 member numbers.

[0044] "Number of carbon atoms" refers to the number of carbon atoms that make up the group. "Hydrogen groups" include linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. These "hydrocarbon groups" may be either saturated or unsaturated hydrocarbon groups. "Linear hydrocarbon groups" refer to hydrocarbon groups that do not contain a cyclic structure and consist only of a linear structure, and include both straight-chain and branched-chain hydrocarbon groups. "Alicyclic hydrocarbon groups" refer to hydrocarbon groups that contain only an alicyclic ring as a ring structure and do not contain an aromatic ring, and include both monocyclic and polycyclic alicyclic hydrocarbon groups. However, they do not need to consist only of an alicyclic ring; they may contain a linear structure as part of them. "Aromatic hydrocarbon groups" refer to hydrocarbon groups that contain an aromatic ring as a ring structure. However, they do not need to consist only of an aromatic ring; they may contain a linear structure or an alicyclic ring as part of them.

[0045] R X , R Y , R Z , R B or R C Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0046] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, isobutyl, and tert-butyl groups; alkenyl groups such as ethenyl, propenyl, butenyl, and 2-methylpropane-1-en-1-yl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0047] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl and cyclohexyl groups, polycyclic alicyclic saturated hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups, monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl and cyclohexenyl groups, and polycyclic alicyclic unsaturated hydrocarbon groups such as norborneyl, tricyclodecenyl, and tetracyclododecenyl groups.

[0048] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0049] R Y and R Z Examples of saturated alicyclic rings with 3 to 20 members, formed by combining these rings with the carbon atoms to which they are bonded, include monocyclic saturated alicyclic rings such as cyclopropane rings, cyclobutane rings, cyclopentane rings, and cyclohexane rings, and polycyclic saturated alicyclic rings such as norbornane rings, adamantane rings, tricyclodecane rings, and tetracyclododecane rings.

[0050] R D Examples of divalent hydrocarbon groups having 1 to 20 carbon atoms represented by the above R X , R Y , R Z , R B or R C Examples include groups obtained by removing one hydrogen atom from the group exemplified as a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by .

[0051] R D R A , R B and R CExamples of unsaturated alicyclic rings with 4 to 20 members, each bonded to a carbon atom, include monocyclic unsaturated alicyclic rings such as cyclobutene rings, cyclopentene rings, and cyclohexene rings, and polycyclic unsaturated alicyclic rings such as norbornene rings.

[0052] R T From the viewpoint of copolymerization of the monomer that gives structural unit (II), a hydrogen atom or a methyl group is preferred.

[0053] R X The group is preferably a chain hydrocarbon group or an aromatic hydrocarbon group, more preferably an alkyl group, an alkenyl group or an aryl group, and even more preferably a methyl group, an ethyl group, an i-propyl group, a tert-butyl group, an ethenyl group or a phenyl group.

[0054] R Y and R Z Preferably, these are part of a saturated alicyclic ring with 3 to 20 members, formed by combining them with the carbon atoms to which they are bonded. Preferred saturated alicyclic rings include cyclopentane rings, cyclohexane rings, adamantane rings, or tetracyclododecane rings.

[0055] R B A hydrogen atom is preferred as the element.

[0056] R C A chain-like hydrocarbon group is preferred, an alkyl group is more preferred, and a methyl group is even more preferred.

[0057] R D R A , R B and R C As for the unsaturated alicyclic ring with 4 to 20 members that is formed together with the carbon atoms to which each is bonded, a monocyclic unsaturated alicyclic ring is preferred, and a cyclohexene ring is more preferred.

[0058] Examples of structural units (II-1) include structural units represented by the following formulas (II-1-1) to (II-1-9) (hereinafter also referred to as "structural units (II-1-1) to (II-1-9)"). Examples of structural units (II-2) include 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)").

[0059] [ka]

[0060] In the above equations (II-1-1) to (II-1-9) and (II-2-1) to (II-2-2), R T This is equivalent to equations (II-1) and (II-2) above.

[0061] The lower limit of the content of structural unit (II) in polymer [A] is preferably 30 mol%, and more preferably 40 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 70 mol%, and more preferably 60 mol%.

[0062] [Structural Unit (III)] Structural unit (III) is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to hydroxyl groups directly attached to a benzene ring, but to all hydroxyl groups directly attached to an aromatic ring.

[0063] [A]When the polymer has structural unit (III), the hydrophilicity of the resist film can be increased, the solubility in the developer can be appropriately adjusted, and in addition, the adhesion of the resist pattern to the substrate can be improved. Furthermore, when extreme ultraviolet (EUV) or electron beams are used as the radiation irradiated in the exposure step in the resist pattern formation method described later, the sensitivity to exposure light can be further improved. Therefore, when the polymer has structural unit (III), the radiation-sensitive resin composition can be particularly suitably used as a radiation-sensitive resin composition for extreme ultraviolet exposure or electron beam exposure.

[0064] Examples of structural units (III) include the structural unit represented by the following formula (III-1) (hereinafter also referred to as "structural unit (III-1)").

[0065] [ka]

[0066] In the above equation (III-1), R P L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 The bond is a single bond, -COO-, -O-, or -CONH-. 2 This group is obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring with 6 to 30 members. n is an integer between 1 and 3.

[0067] R P From the viewpoint of copolymerization of the monomer that gives structural unit (III-1), a hydrogen atom or a methyl group is preferred.

[0068] L 2 A single bond or a -COO- is preferred.

[0069] Ar 2Examples of aromatic hydrocarbon rings with 6 to 30 members that give the property include benzene rings; condensed polycyclic aromatic hydrocarbon rings such as naphthalene rings, anthracene rings, fluorene rings, biphenylene rings, phenanthrene rings, and pyrene rings; and ring-assemble aromatic hydrocarbon rings such as biphenyl rings, terphenyl rings, binaphthalene rings, and phenylnaphthalene rings. Among these, benzene rings or naphthalene rings are preferred.

[0070] Substituents that the above aromatic hydrocarbon ring may have include halogen atoms such as fluorine atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and the like.

[0071] n is preferably 1 or 2.

[0072] Examples of structural units (III-1) include those represented by the following formulas (III-1-1) to (III-1-12) (hereinafter also referred to as "structural units (III-1-1) to (III-1-12)").

[0073] [ka]

[0074] In the above equations (III-1-1) to (III-1-12), R P This is equivalent to equation (III-1) above.

[0075] [A]When polymer has structural unit (III), the lower limit of the content of structural unit (III) is preferably 5 mol%, and more preferably 10 mol%, relative to the total structural units in polymer [A]. The upper limit of the above content is preferably 70 mol%, and more preferably 60 mol%.

[0076] [Other structural units] Other structural units are structural units other than structural units (I) to (III) described above. Other structural units can be selected from known monomers used as polymers of radiation-sensitive resin compositions, to the extent that they do not impair the effects of the present invention. Examples of other structural units include structural units containing lactone structures, cyclic carbonate structures, sultone structures or combinations thereof (hereinafter also referred to as "structural unit (IV)"), structural units containing alcoholic hydroxyl groups (hereinafter also referred to as "structural unit (V)"), and structural units that generate acid upon exposure (hereinafter also referred to as "structural unit (VI)").

[0077] [A] If the polymer has other structural units, the proportion of these other structural units can be appropriately determined according to the type and purpose of the other structural units. For example, it can be between 1 mol% and 20 mol% relative to the total structural units in the polymer [A].

[0078] (Structural Unit (IV)) Structural unit (IV) is a structural unit that includes a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. [A]When the polymer has structural unit (IV), the hydrophilicity of the resist film can be increased and the solubility in the developer can be appropriately adjusted.

[0079] Examples of structural units (IV) include structural units represented by the following formula.

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] In the above formula, R L1 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0085] The structural unit (IV) is preferably a structural unit that includes a lactone structure, a cyclic carbonate structure, or a combination thereof.

[0086] (Structural unit (V)) Structural unit (V) is a structural unit containing an alcoholic hydroxyl group. [A]When the polymer has structural unit (V), the hydrophilicity of the resist film can be increased, the solubility in the developer can be appropriately adjusted, and in addition, the adhesion of the resist pattern to the substrate can be improved.

[0087] Examples of structural units (V) include structural units represented by the following formula.

[0088] [ka]

[0089] In the above formula, R L2 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0090] (Structural Unit (VI)) Structural unit (VI) is a structural unit that generates acid upon exposure. When a polymer has structural unit (VI), it also functions as a radiation-sensitive acid generator.

[0091] Examples of structural units (VI) include structural units represented by the following formula.

[0092] [ka]

[0093] In the above formula, R L3 This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. + It is a monovalent radiation-sensitive onium cation.

[0094] Y + Examples of monovalent radiation-sensitive onium cations represented by include those similar to those exemplified as monovalent radiation-sensitive onium cations in the [C] acid diffusion control agent described later.

[0095] <[B] Acid Generator> [B] The acid generator is a substance that generates acid upon exposure. Examples of exposure light include those similar to those exemplified as exposure light in the exposure step of the resist pattern formation method described later. The acid generated by exposure causes the acid-dissociable groups of the [A] polymer, etc., to dissociate, generating carboxyl groups, hydroxyl groups, etc., and a difference in the solubility of the resist film in the developer between the exposed and unexposed areas occurs, thereby forming a resist pattern.

[0096] [B] Examples of acids generated from acid generators include sulfonic acids and imido acids.

[0097] [B] Examples of acid generators include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds.

[0098] Examples of onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0099] [B]Specific examples of acid generators include, for example, the compounds described in paragraphs

[0080] to

[0113] of Japanese Patent Publication No. 2009-134088.

[0100] Examples of [B] acid generators that produce sulfonic acid upon exposure include compounds represented by the following formula (2) (hereinafter also referred to as "[B] compound").

[0101] [ka]

[0102] In equation (2) above, R p1 R is a monovalent group containing a ring structure with 5 or more members. p2 R is a divalent linking group. p3 and R p4 Each of these is 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. p5 and R p6 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. p1 n is an integer between 0 and 10. p2 n is an integer between 0 and 10. p3 n is an integer between 0 and 10. p1 If there are 2 or more, multiple R p2 They are either identical or different from each other. p2 If there are 2 or more, multiple R p3 They are either identical or different from each other, and multiple R p4 They are either identical or different from each other. p3 If there are 2 or more, multiple R p5 They are either identical or different from each other, and multiple R p6 They are either identical or different from each other. + It is a monovalent radiation-sensitive onium cation.

[0103] R p1 Examples of ring structures with 5 or more members include alicyclic rings with 5 or more members, aliphatic heterocyclic rings with 5 or more members, aromatic hydrocarbon rings with 6 or more members, and aromatic heterocyclic rings with 5 or more members.

[0104] Examples of alicyclic rings with five or more members include monocyclic saturated alicyclic rings such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and cyclododecane rings; monocyclic unsaturated alicyclic rings such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene rings; polycyclic saturated alicyclic rings such as norbornane, adamantane, tricyclodecane, and tetracyclododecane rings; and polycyclic unsaturated alicyclic rings such as norbornene and tricyclodecene rings.

[0105] Examples of aliphatic heterocycles with 5 or more members include lactone rings such as hexanolactone rings and norbornanelactone rings, sultone rings such as hexanosultone rings and norbornanesultone rings, oxygen-containing heterocycles such as oxacycloheptane rings, oxanorbornane rings and acetal rings, nitrogen-containing heterocycles such as azacyclohexane rings and diazabicyclooctane rings, and sulfur-containing heterocycles such as thiacyclohexane rings and thianorbornane rings.

[0106] Examples of aromatic hydrocarbon rings with 6 or more members include benzene rings, naphthalene rings, phenanthrene rings, anthracene rings, and 9,10-ethanoanthracene rings.

[0107] Examples of aromatic heterocycles with five or more members include oxygen-containing heterocycles such as furan rings, pyran rings, benzofuran rings, and benzopyran rings, and nitrogen-containing heterocycles such as pyridine rings, pyrimidine rings, and indole rings.

[0108] R p1 The lower limit of the number of ring members in the ring structure is preferably 6, more preferably 8, even more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, even more preferably 13, and particularly preferably 12. By setting the number of ring members within the above range, the diffusion length of the acid can be further appropriately shortened, and as a result, the sensitivity and LWR performance of the radiation-sensitive resin composition can be further improved, and the process window can be further expanded.

[0109] R p1 Some or all of the hydrogen atoms in the ring structure of may be substituted with substituents. Examples of the substituents include halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like. Among these, hydroxy group, fluorine atom or iodine atom is preferable.

[0110] R p1 As, a monovalent group containing an alicyclic ring having 5 or more ring members, a monovalent group containing an aromatic hydrocarbon ring having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic ring having 5 or more ring members is preferable, and a monovalent group containing a polycyclic saturated alicyclic ring, a monovalent group containing an aromatic hydrocarbon ring having 6 or more ring members containing an iodine atom, a monovalent group containing an oxygen atom-containing heterocyclic ring or a monovalent group containing a sulfur atom-containing heterocyclic ring is more preferable.

[0111] R p2 Examples of the divalent linking group represented by include carbonyl group, ether group, carbonyloxy group, sulfide group, thiocarbonyl group, sulfonyl group, divalent hydrocarbon group and the like.

[0112] R p3 and R p4 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by and R include an alkyl group having 1 to 20 carbon atoms and the like. R p3 and R p4 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by and R include a fluorinated alkyl group having 1 to 20 carbon atoms and the like. R p3 and R p4 As, a hydrogen atom, a fluorine atom or a fluorinated alkyl group is preferable, a hydrogen atom, a fluorine atom or a perfluoroalkyl group is more preferable, and a hydrogen atom, a fluorine atom or a trifluoromethyl group is further preferable.

[0113] R p5 and R p6Examples of monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as represented by R, include fluorinated alkyl groups having 1 to 20 carbon atoms. p5 and R p6 Preferably, the component is a fluorine atom or a fluorinated alkyl group, more preferably a fluorine atom or a perfluoroalkyl group, even more preferably a fluorine atom or a trifluoromethyl group, and particularly preferably a fluorine atom.

[0114] n p1 Preferably, the value is 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0115] n p2 Preferably, the value is 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0116] n p3 The lower limit is preferably 1, and more preferably 2. p3 By setting n to 1 or greater, the acidity can be increased. p3 The upper limit is preferably 4, more preferably 3, and even more preferably 2.

[0117] Y + Examples of monovalent radiation-sensitive onium cations represented by include those similar to those exemplified as monovalent radiation-sensitive onium cations in the [C] acid diffusion control agent described later.

[0118] [B] Examples of compounds include those represented by the following formulas (2-1) to (2-11).

[0119] [ka]

[0120] In the above equations (2-1) to (2-11), Y + This is equivalent to equation (2) above.

[0121] The lower limit of the content of the [B] acid generator in the radiation-sensitive resin composition is preferably 1 part by mass, more preferably 5 parts by mass, and still more preferably 10 parts by mass, per 100 parts by mass of the [A] polymer. The upper limit of the above content is preferably 50 parts by mass, more preferably 40 parts by mass, and still more preferably 30 parts by mass.

[0122] <[C] Acid diffusion control agent> [C] The acid diffusion control agent is a compound having a monovalent radiation-sensitive onium cation and a monovalent organic acid anion. [C] The acid diffusion control agent controls the diffusion phenomenon of acid generated from [B] the acid generator etc. in the resist film upon exposure, and has the effect of controlling undesirable chemical reactions in the non-exposed areas. Although the acid diffusion control agent is a compound that generates acid upon exposure and can therefore be broadly called an acid generator, [C] the acid diffusion control agent is a compound that generates an acid that does not dissociate the acid-dissociable group upon exposure, under conditions where the acid generated from [B] the acid generator upon exposure dissociates the acid-dissociable group.

[0123] Examples of monovalent radiosensitive onium cations include the monovalent cation represented by the following formulas (ra) to (rb) (hereinafter also referred to as "cation (ra) to (rb)").

[0124] [ka]

[0125] In the above equation (ra), b1 is an integer from 0 to 4. When b1 is 1, R B1 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b1 is 2 or more, multiple R B1 These are identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure with 4 to 20 members, formed by these groups combined with the carbon chain to which they are bonded. b2 is an integer from 0 to 4. If b2 is 1, R B2is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b2 is 2 or more, multiple R B2 These are either identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure with 4 to 20 members, formed by these groups combined with the carbon chain to which they are bonded. B3 and R B4 Each of these is independently a hydrogen atom, a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or these are combined to represent a single bond. b3 is an integer from 0 to 11. When b3 is 1, R B5 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b3 is 2 or more, multiple R B5 These are either identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure with 4 to 20 members, formed by these groups combined with the carbon chain to which they are bonded. b1 This is an integer between 0 and 3.

[0126] In the above equation (rb), b4 is an integer between 0 and 5. When b4 is 1, R B6 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b4 is 2 or more, multiple R B6 These are identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure with 4 to 20 members, formed by these groups combined with the carbon chain to which they are bonded. b5 is an integer from 0 to 5. If b5 is 1, R B7 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b5 is 2 or more, multiple R B7 These are either identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen atoms having 1 to 20 carbon atoms, or are part of a ring structure with 4 to 20 members, formed by these groups combined with the carbon chain to which they are bonded.

[0127] An "organic group" is a group that contains at least one carbon atom.

[0128] R B1 , R B2 , R B3 , R B4 , R B5 and R B6 Examples of monovalent organic groups having 1 to 20 carbon atoms represented by include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups (α) containing a divalent heteroatom-containing group between the carbon atoms of the hydrocarbon group, groups (β) in which some or all of the hydrogen atoms of the hydrocarbon group or group (α) are replaced with a monovalent heteroatom-containing group, and groups (γ) which are combinations of the hydrocarbon group, group (α), or group (β) with a divalent heteroatom-containing group.

[0129] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include R in formula (II-1) above. X , R Y or R Z Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, as represented by the formula, include groups similar to those exemplified above.

[0130] Examples of heteroatoms constituting a monovalent or divalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0131] Examples of divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups formed by combining two or more of these (e.g., -COO-, -CONR'-, etc.). R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0132] R B1 , R B2 , R B3 , R B4 , R B5 and R B6Preferably, the halogen atom or a group in which some or all of the hydrogen atoms of a monovalent hydrocarbon group having 1 to 20 carbon atoms are substituted with a monovalent halogen atom. In this case, a fluorine atom is preferred as the halogen atom. In this case, a good balance can be achieved between the sensitivity, LWR performance, and process window of the radiation-sensitive resin composition.

[0133] R B3 and R B4 Preferably, these are hydrogen atoms or single bonds formed by combining them.

[0134] b1, b2, and b3 are preferably 0 to 3. b1 0 or 1 is preferred.

[0135] For b4 and b5, 0 or 1 is preferred.

[0136] Examples of cations (ra) include cations represented by the following formulas (ra-1) to (ra-12) (hereinafter also referred to as "cations (ra-1) to (ra-12)"). Examples of cations (rb) include cations represented by the following formula (rb-1) (hereinafter also referred to as "cation (rb-1)").

[0137] [ka]

[0138] Examples of monovalent organic acid anions include carboxylic acid anions. Examples of carboxylic acid anions include the anions represented by the following formulas (3-1) to (3-9) (hereinafter also referred to as "anions (3-1) to (3-9)").

[0139] [ka]

[0140] [C] As an acid diffusion control agent, a compound obtained by appropriately combining the above cation and the above anion can be used.

[0141] The lower limit of the content of the [C] acid diffusion control agent in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%, per 100 mol% of the [B] acid generator. The upper limit of the above content is preferably 100 mol%, more preferably 50 mol%, and even more preferably 30 mol%.

[0142] <[D] Organic solvent> The radiation-sensitive resin composition typically contains an organic solvent [D]. The organic solvent [D] is not particularly limited as long as it is capable of dissolving or dispersing at least the polymer [A], the acid generator [B], and the acid diffusion control agent [C], as well as any other optional components that may be present.

[0143] [D] Examples of organic solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, hydrocarbon-based solvents, etc. [D] One or more organic solvents may be included.

[0144] Examples of alcohol-based solvents 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 monomethyl ether.

[0145] Examples of ether-based 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.

[0146] Examples of ketone solvents include linear 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.

[0147] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone, and chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0148] 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, polyhydric carboxylic acid diester solvents such as diethyl oxalate, and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

[0149] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents with 5 to 12 carbon atoms, such as n-pentane and n-hexane, and aromatic hydrocarbon solvents with 6 to 16 carbon atoms, such as toluene and xylene.

[0150] [D] As organic solvents, alcohol-based solvents, ester-based solvents, or combinations thereof are preferred, polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms, polyhydric alcohol partial ether carboxylate solvents, or combinations thereof are more preferred, and propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or combinations thereof are even more preferred.

[0151] If the radiation-sensitive resin composition contains an organic solvent [D], the lower limit of the content of the organic solvent [D] is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and particularly preferably 80% by mass, relative to the total components contained in the radiation-sensitive resin composition. The upper limit of the above content is preferably 99.9% by mass, more preferably 99.5% by mass, and even more preferably 99.0% by mass.

[0152] <Other optional ingredients> Other optional components include, for example, surfactants. The radiation-sensitive resin composition may contain one or more of these other optional components.

[0153] <Method for forming a resist pattern> The resist pattern formation method comprises the steps of directly or indirectly coating a substrate with a radiation-sensitive resin composition (hereinafter also referred to as the "coating step"), exposing the resist film formed by the coating (hereinafter also referred to as the "exposure step"), and developing the exposed resist film (hereinafter also referred to as the "development step").

[0154] In the above coating process, the aforementioned radiation-sensitive resin composition is used as the radiation-sensitive resin composition. Therefore, according to this resist pattern formation method, it is possible to form a resist pattern with excellent sensitivity and LWR performance and a wide process window.

[0155] The following describes each step of the resist pattern formation method.

[0156] [Coating Process] In this process, a radiation-sensitive resin composition is applied to the substrate directly or indirectly. This forms a resist film on the substrate, either directly or indirectly.

[0157] In this process, the above-mentioned radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

[0158] Examples of substrates include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers.

[0159] Examples of coating methods include rotary coating (spin coating), casting coating, and roll coating. After coating, pre-baking (hereinafter also referred to as "PB") may be performed as needed to volatilize the solvent in the coating film. The lower limit of the PB temperature is preferably 60°C, and more preferably 80°C. The upper limit of the above temperature is preferably 150°C, and more preferably 140°C. The lower limit of the PB time is preferably 5 seconds, and more preferably 10 seconds. The upper limit of the above time is preferably 600 seconds, and more preferably 300 seconds. The lower limit of the average thickness of the formed resist film is preferably 10 nm, and more preferably 20 nm. The upper limit of the above average thickness is preferably 1,000 nm, and more preferably 500 nm.

[0160] [Synthesis process] In this step, the resist film formed by the above coating step is exposed. This exposure is performed by irradiating exposure light through a photomask (and, in some cases, through an immersion medium such as water). The exposure light is preferably far ultraviolet light, EUV, or an electron beam, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or an electron beam, even more preferably KrF excimer laser light, EUV, or an electron beam, and particularly preferably EUV or an electron beam.

[0161] After the above exposure, it is preferable to perform a post-exposure bake (hereinafter also referred to as "PEB"). This PEB can increase the difference in solubility in the developer between the exposed and unexposed areas. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°C. The upper limit of the temperature is preferably 180°C, more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and still more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and still more preferably 100 seconds.

[0162] [Development process] In this step, the exposed resist film is developed. This allows for the formation of a predetermined resist pattern. The development method in the development step may be alkaline development or organic solvent development.

[0163] In the case of alkaline development, examples of developer solutions used for development include alkaline aqueous solutions containing 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, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0164] In the case of organic solvent development, the developer can be an organic solvent such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, or alcohol solvents, or a solution containing the above organic solvents. Examples of the above organic solvents include the solvents exemplified as the [D] organic solvent in the above-mentioned radiation-sensitive resin composition. [Examples]

[0165] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring each physical property are shown below.

[0166] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity (Mw / Mn)] The Mw and Mn of the polymer were measured according to the conditions described in the section [Measurement Method for Mw and Mn] above. The polydispersity (Mw / Mn) of the polymer was calculated from the measured Mw and Mn results.

[0167] <[X]Synthesis of monomers> Compounds represented by the following formulas (X-1) to (X-34) as [X] monomers (hereinafter also referred to as "monomers (X-1) to (X-34)") were synthesized according to the following method.

[0168] [ka]

[0169] [Synthesis Example 1-1] Synthesis of monomer (X-1) 200 g of 9-antrol and 156 g of triethylamine were dissolved in 1,500 mL of dichloromethane. After cooling the solution to 0°C, 108 g of methacryloyl chloride was added dropwise at a rate that did not cause the solution temperature to exceed 25°C. After the addition was complete, the mixture was stirred at 25°C for 1 hour. After the reaction was complete, the mixture was quenched with a saturated aqueous solution of ammonium chloride and extracted with methylene chloride. The residue obtained by concentration under reduced pressure was purified by column chromatography to obtain 148 g of monomer (X-1) (yield 55%).

[0170] The synthesis scheme for monomer (X-1) is shown below. In the synthesis scheme below, NEt3 is triethylamine.

[0171] [ka]

[0172] [Synthesis Examples 1-2~1-16 and 1-19~1-32] Synthesis of monomers (X-2)~(X-16) and (X-19)~(X-32) Monomers (X-2) to (X-16) and (X-19) to (X-32) were synthesized in the same manner as in Synthesis Example 1-1, except that the precursors were appropriately selected.

[0173] [Synthesis Example 1-17] Synthesis of monomer (X-17) 185 g of anthracene-9-carbonyl chloride was dissolved in 1,500 mL of dichloromethane. After cooling the solution to 0°C, 100 g of 2-hydroxyethyl methacrylate and 117 g of triethylamine were added dropwise at a rate that did not exceed 25°C. After the addition was complete, the mixture was stirred at 25°C for 1 hour. After the reaction was complete, the mixture was quenched with a saturated aqueous solution of ammonium chloride and extracted with methylene chloride. The residue obtained by concentration under reduced pressure was purified by column chromatography to obtain 135 g of monomer (X-17) (yield 53%).

[0174] The synthesis scheme for monomer (X-17) is shown below. In the synthesis scheme below, NEt3 is triethylamine.

[0175] [ka]

[0176] [Synthesis Example 1-18] Synthesis of monomer (X-18) The monomer (X-18) was synthesized in the same manner as in synthesis example 1-17, except that the precursor was appropriately selected.

[0177] <[A] Synthesis of polymers> Polymers (A-1) to (A-70) and (CA-1) to (CA-6) were synthesized as polymers of [A] according to the following method. Monomers (X-1) to (X-32) and compounds represented by the following formulas (M-1) to (M-29) and (CX-1) to (CX-3) (hereinafter also referred to as "monomers (M-1) to (M-29) and (CX-1) to (CX-3)") were used for the synthesis of polymers of [A]. In the following synthesis examples, unless otherwise specified, "parts by mass" means the value when the total mass of the monomers used is 100 parts by mass, and "mol%" means the value when the total number of moles of the monomers used is 100 mol%.

[0178] [ka]

[0179] [Synthesis Example 2-1] Synthesis of Polymer (A-1) Monomer (X-1), monomer (M-1), and monomer (M-13) were dissolved in propylene glycol monomethyl ether (200 parts by mass relative to the total amount of monomer) in a molar ratio of 10 / 40 / 50. Next, azobisisobutyronitrile (hereinafter also referred to as "AIBN") was added as an initiator at a concentration of 6 mol% relative to the total amount of monomer to prepare a monomer solution. Meanwhile, propylene glycol monomethyl ether (100 parts by mass relative to the total amount of monomer) 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 a further 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution. Subsequently, it was dissolved again in propylene glycol monomethyl ether (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 the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation. The obtained solid was dissolved in acetone (100 parts by mass). The resin was solidified by dropping it into 500 parts by mass of water, and the obtained solid was filtered off. It was dried at 50°C for 12 hours to obtain a white powdery polymer (A-1). The Mw of polymer (A-1) was 7,900, and the Mw / Mn ratio was 1.6.

[0180] [Synthesis Examples 2-2 to 2-64 and 2-71 to 76] Synthesis of polymers (A-2) to (A-64) and (CA-1) to (CA-6) Polymers (A-2) to (A-64) and (CA-1) to (CA-6) were synthesized in the same manner as in Synthesis Example 2-1, except that the monomers used were of the types and amounts shown in Table 1 below.

[0181] [Synthesis Examples 2-65~2-69] Synthesis of polymers (A-65)~(A-69) Polymers (A-65) to (A-69) were synthesized in the same manner as in Synthesis Example 2-3, except that the amount of the starting agent was changed as appropriate.

[0182] [Synthesis Example 2-70] Synthesis of Polymer (A-70) Monomers (X-1), (M-7), (M-13), and (M-29) were dissolved in 2-butanone (200 parts by mass relative to the total amount of monomers) in a molar ratio of 30 / 10 / 50 / 10. AIBN was added as an initiator at a concentration of 6 mol% relative to the total amount of monomers to prepare the monomer solution. Meanwhile, 2-butanone (100 parts by mass) was placed in an empty reaction vessel and heated to 80°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours. After that, the mixture was heated at 80°C for another 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to methanol (2,000 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The obtained solid was dissolved in acetone (100 parts by mass). This was added dropwise to 500 parts by mass of water, and the solidified solid was filtered off. The polymer (A-70) was dried at 50°C for 12 hours to obtain a white powder. The Mw of polymer (A-70) was 8,400, and the Mw / Mn ratio was 1.7.

[0183] Table 1 below shows the types and proportions of monomers that give each structural unit of the [A] polymer obtained in Synthesis Examples 2-1 to 2-76, as well as Mw and Mw / Mn. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0184] [Table 1]

[0185] <Preparation of radiation-sensitive resin composition> The following are the [B] acid generator, [C] acid diffusion control agent, and [D] organic solvent used in the preparation of the radiation-sensitive resin composition. In the following examples and comparative examples, unless otherwise specified, "parts by mass" means the value when the mass of the [A] polymer used is 100 parts by mass, and "mol%" means the value when the number of moles of the [B] acid generator used is 100 mol%.

[0186] [[B] Acid Generator] [B] As an acid generator, compounds represented by the following formulas (B-1) to (B-18) (hereinafter also referred to as "acid generators (B-1) to (B-18)") were used.

[0187] [ka]

[0188] [[C] Acid diffusion control agent] [C] As acid diffusion control agents, compounds represented by the following formulas (C-1) to (C-12) and (CC-1) (hereinafter also referred to as "acid diffusion control agents (C-1) to (C-12) and (CC-1)") were used. Note that acid diffusion control agent (CC-1) does not fall under the category of "acid diffusion control agents having a monovalent radiosensitive onium cation and a monovalent organic acid anion".

[0189] [ka]

[0190] [[D] Organic solvents] [D] The following organic solvents were used as organic solvents. (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol monomethyl ether

[0191] [Example 1] Preparation of radiation-sensitive resin composition (R-1) [A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] 20 mol% of (C-1) relative to (B-1) as an acid diffusion control agent, and [D] 4,800 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as organic solvents were mixed. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare a radiation-sensitive resin composition (R-1).

[0192] [Examples 2-98 and Comparative Examples 1-7] Preparation of radiation-sensitive resin compositions (R-2)-(R-98) and (CR-1)-(CR-7) Radiation-sensitive resin compositions (R-2) to (R-98) and (CR-1) to (CR-7) were prepared in the same manner as in Example 1, except that the components used were of the types and in the amounts shown in Tables 2 and 3 below.

[0193] <Resist pattern formation> A 12-inch silicon wafer surface, on which an underlayer film (Brewer Science's "AL412") with an average thickness of 20 nm had been formed, was coated with the radiation-sensitive resin composition prepared above using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). After pre-baking (PB) at 130°C for 60 seconds, the wafer 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 (ASML's "NXE3300", NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). After irradiation, the resist film was subjected to post-exposure baking (PEB) at 110°C for 60 seconds. Subsequently, a 2.38 mass% TMAH aqueous solution was used as the alkaline developer, and development was performed at 23°C for 30 seconds to form a positive-type 32 nm line and space pattern.

[0194] <Rating> The resist patterns formed as described above were evaluated for sensitivity, LWR performance, and process window according to the following method. A scanning electron microscope (Hitachi High-Tech Corporation's "CG-4100") was used to measure the length of the resist patterns. The evaluation results are shown in Tables 2 and 3 below.

[0195] [sensitivity] In forming the resist pattern described above, the exposure amount used to form the 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as Eop (unit: mJ / cm²). 2 ) was used. Sensitivity is better when the Eop value is small.

[0196] [LWR performance] The resist pattern formed as described above was observed from above using the scanning electron microscope. The line width was measured at 50 points in arbitrary locations, and the 3-sigma value was determined from the distribution of the measured values, which was designated as LWR (unit: nm). The LWR performance indicates that the smaller the value of LWR, the better.

[0197] [Process Window] Using a mask for forming 32 nm line and space (1L / 1S), patterns from a low exposure amount to a high exposure amount were formed. Generally, in the case of a low exposure amount, defects such as bridge formation between patterns are observed, and in the case of a high exposure amount, defects such as pattern collapse are observed. The difference between the maximum value and the minimum value of the resist dimension where these defects are not observed was defined as the CD (Critical Demension) margin (unit: nm). The larger the value of the CD margin, the wider the process window and the better it indicates.

[0198]

Table 2

[0199]

Table 3

Claims

1. A polymer having a first structural unit represented by the following formula (1), wherein its solubility in a developer changes upon the action of an acid, A radiation-sensitive acid generator, An acid diffusion control agent having a monovalent radiation-sensitive onium cation and a monovalent organic acid anion. A radiation-sensitive resin composition containing [a specific substance]. 【Chemistry 1】 (In formula (1), R １ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ Ar is a single bond or a divalent linking group. １ (This refers to a group obtained by removing one hydrogen atom from a substituted or unsubstituted condensed tetracyclic aromatic hydrocarbon ring with 16 or more members.)

2. The radiation-sensitive resin composition according to claim 1, wherein the number of ring members of the condensed tetracyclic aromatic hydrocarbon ring is 16 or more and 18 or less.

3. The radiation-sensitive resin composition according to claim 1, wherein the above-mentioned condensed tetracyclic aromatic hydrocarbon ring is a pyrene ring.

4. The radiation-sensitive resin composition according to claim 1, wherein the polymer further comprises a second structural unit containing an acid-dissociable group.

5. The radiation-sensitive resin composition according to claim 1, wherein the polymer further comprises a third structural unit containing a phenolic hydroxyl group.

6. A step of coating a substrate directly or indirectly with the radiation-sensitive resin composition described in any one of claims 1 to 5, A step of exposing the resist film formed by the above coating, The process of developing the exposed resist film described above A resist pattern formation method comprising the following:

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