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

Abstract

To provide a radiation sensitive resin composition, and a resist pattern formation method, capable of forming a resist pattern excellent in sensitivity to exposure light, and further excellent in LWR performance and CDU performance.SOLUTION: A radiation sensitive resin composition includes a polymer having a first structural unit shown by formula (1), in which solubility into a developer is changed by action of acid, and a radiation-sensitive acid generator.SELECTED DRAWING: None

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) and CDU (Critical Dimension Uniformity) performance.

[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 project] [Problems that the invention aims to solve]

[0006] With the miniaturization of resist patterns progressing to a level of line width of 40 nm or less, the required level of performance has become even higher, and the conventional radiation-sensitive resin compositions described above are unable to satisfy 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 method for forming a resist pattern that has good sensitivity to exposure light and can form a resist pattern with excellent LWR performance and CDU performance. [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"), and a radiation-sensitive acid generator (hereinafter also referred to as "[B] acid generator). [ka] (In formula (1), R 1 L is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, -COO-, -O-, or -CONH-. 1 This is a group obtained by removing (m+2) hydrogen atoms from an aromatic ring with 6 to 30 members. X consists of single bonds, -O-, -GO-, -S-, -SO2-, and -NR. A -or -CONH- R A G is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. G is a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms. Ar 2 R is a group obtained by removing (n+1) hydrogen atoms from an aromatic ring with 6 to 30 members. 2 and R 3is independently an organic group having 1 to 20 carbon atoms, a halogen atom, a hydroxy group or a sulfanyl group. m is an integer of 0 to 10. When m is 2 or more, a plurality of R 2 are the same as or different from each other. n is an integer of 0 to 10. When n is 2 or more, a plurality of R 3 are the same as or different from each other. )

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

Effect of the Invention

[0010] 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 and excellent LWR performance and CDU performance can be formed. Therefore, the radiation-sensitive resin composition and the resist pattern forming method can be suitably used in the processing process of semiconductor devices and the like, which are expected to be further miniaturized in the future.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the radiation-sensitive resin composition and the 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] polymer and [B] acid generator. 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 an acid diffusion control agent (hereinafter also referred to as "[C] acid diffusion control agent") as a preferred component. The radiation-sensitive resin composition may contain a polymer (hereinafter also referred to as "[E] polymer) with a higher mass content of fluorine atoms than the [A] polymer as a preferred component. 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, by containing a polymer [A] and an acid generator [B], exhibits good sensitivity to exposure light and can form a resist pattern with excellent LWR and CDU performance. 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: The polymer [A] contained in the radiation-sensitive resin composition has a structural unit represented by formula (1) above, which allows for the introduction of substituents with various functions. As a result, the radiation-sensitive resin composition is thought to exhibit good sensitivity to exposure light and can form a resist pattern with excellent LWR and CDU performance.

[0014] The following describes each component contained in the radiation-sensitive resin composition.

[0015] [[A] Polymerization] [A] polymers are polymers having a structural unit represented by formula (1) described later (hereinafter also referred to as "structural unit (I)"), and whose solubility in a developer changes upon the action of an acid. Typically, the property of [A] polymers changing their solubility in a developer upon the action of an acid is exhibited because they have an acid-dissociable group. [A] polymers may have an acid-dissociable group in structural unit (I), or they may further have a structural unit containing an acid-dissociable group as a structural unit different from structural unit (I) (hereinafter also referred to as "structural unit (II)"), or both.

[0016] [A] The polymer preferably further has structural units containing phenolic hydroxyl groups (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. The radiation-sensitive resin composition may contain one or more [A] polymers.

[0017] The following describes each structural unit contained in polymer [A].

[0018] [Structural Unit (I)] Structural unit (I) is a structural unit represented by the following formula (1). By having structural unit (I), substituents with various functions can be introduced without impairing the efficiency of acid generation by exposure. As a result, the radiation-sensitive resin composition has good sensitivity to exposure light and can form a resist pattern with excellent LWR and CDU performance.

[0019] [ka]

[0020] In the above equation (1), R 1 L is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, -COO-, -O-, or -CONH-. 1 This is a group obtained by removing (m+2) hydrogen atoms from an aromatic ring with 6 to 30 members. X consists of single bonds, -O-, -GO-, -S-, -SO2-, and -NR. A - or -CONH-. G is a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms. R A Ar is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. 2 R is a group obtained by removing (n+1) hydrogen atoms from an aromatic ring with 6 to 30 members. 2 and R 3Each of these is independently an organic group having 1 to 20 carbon atoms, a halogen atom, a hydroxyl group, or a sulfanyl group. m is an integer from 0 to 10. If m is 2 or greater, multiple R 2 They are either identical or different from each other. n is an integer between 0 and 10. If n is 2 or greater, multiple R 3 They are either identical or different from one another.

[0021] "Ring member number" refers to the number of atoms that make up the ring structure, and in the case of polycyclic rings, it refers to the number of atoms that make up this polycyclic ring. "Aromatic rings" include "aromatic hydrocarbon rings" and "aromatic heterocyclic rings." "Aromatic rings" include "monocyclic aromatic rings" and "polycyclic aromatic rings." "Polycyclic aromatic rings" include not only fused polycyclic rings in which two rings have two shared atoms, but also ring-assembly type polycyclic rings in which two rings do not have shared atoms and are connected by a single bond.

[0022] "Number of carbon atoms" refers to the number of carbon atoms that make up a group. "Organic group" refers to a group that contains at least one carbon atom. "Hydrogen group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. "Linear hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a linear structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as its ring structure and does not contain an aromatic ring structure, and includes both monocyclic and polycyclic alicyclic hydrocarbon groups. However, it is not necessary to be composed only of an alicyclic structure, and it may contain a linear structure as part of it. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and it may contain a linear structure or an alicyclic structure as part of it. "Aliphatic hydrocarbon groups" refer to chain hydrocarbon groups and alicyclic hydrocarbon groups.

[0023] R 1 From the viewpoint of copolymerization of the monomer that gives structural unit (I), a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0024] For L, a single bond or -COO- is preferred.

[0025] Ar 1 and Ar 2 Examples of aromatic rings with 6 to 30 members that give the fragrance include aromatic hydrocarbon rings with 6 to 30 members and aromatic heterocycles with 6 to 30 members.

[0026] Examples of aromatic hydrocarbon rings with 6 to 30 members include benzene rings; condensed polycyclic aromatic hydrocarbon rings such as naphthalene rings, phenanthrene rings, and anthracene rings; and ring-aggregated aromatic hydrocarbon rings such as biphenyl rings, terphenyl rings, binaphthalene rings, and phenylnaphthalene rings.

[0027] Examples of aromatic heterocycles with 6 to 30 members include oxygen-containing heterocycles such as pyran rings, benzofuran rings, and benzopyran rings, and nitrogen-containing heterocycles such as pyridine rings, pyrimidine rings, and indole rings.

[0028] Ar 1 and Ar 2 As the aromatic ring having 6 to 30 members that gives the fragrance, an aromatic hydrocarbon ring having 6 to 30 members is preferred, and a benzene ring or a naphthalene ring is more preferred.

[0029] Ar 1 The above aromatic ring and Ar give 2 The aromatic ring that gives the above-mentioned fragrance may be the same or a different aromatic ring, but it is preferable that it be the same aromatic ring.

[0030] X can be -O-, -GO-, -S-, -SO2-, or -NR A - is preferred, -O-, -S- or -SO2- is more preferred, and -O- is even more preferred.

[0031] Examples of the divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by G include those obtained by removing one hydrogen atom from a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, which are exemplified as monovalent hydrocarbon groups having 1 to 20 carbon atoms described later. G is preferably a divalent linear hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic hydrocarbon group having 5 to 20 carbon atoms, more preferably a divalent linear hydrocarbon group having 1 to 4 carbon atoms, and even more preferably a methanediyl group.

[0032] R A Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms, as represented by , include those with 1 to 10 carbon atoms among the examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms described later. A A hydrogen atom is preferred as the element.

[0033] R 2 and R 3 Examples of organic groups having 1 to 20 carbon atoms 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.

[0034] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms 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.

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

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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. Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms represented by R' include the above R A Examples include those similar to those exemplified in [reference].

[0040] R 2 and R 3 In this, fluorine, bromine, or iodine atoms are preferred as halogen atoms. Also, R 2 and R 3 Preferably, at least one of these atoms is a fluorine atom or an iodine atom. In this case, the sensitivity to exposure light, LWR performance, and CDU performance of the radiation-sensitive resin composition can be further improved.

[0041] R 2 and R 3 When the organic group is a monovalent organic group having 1 to 20 carbon atoms, various functional substituents can be introduced into the [A] polymer by appropriately selecting the type of organic group. As a result, a resist pattern with good sensitivity to exposure light and excellent LWR and CDU performance can be formed.

[0042] For m, 0 to 6 is preferred, 1 to 5 is more preferred, and 1 to 4 is even more preferred. For n, 0 to 6 is preferred, 1 to 5 is more preferred, and 1 to 4 is even more preferred. For m+n, 1 or more is preferred.

[0043] The above organic group is preferably a group containing an acid-dissociable group (hereinafter also referred to as "group (I)") or a group containing a polar group (hereinafter also referred to as "group (II)").

[0044] (Basic (I)) Group (I) is a group 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.

[0045] When the above organic group is group (I), the acid-dissociable group of group (I) causes the polymer [A] to exhibit a property where its solubility in the developer changes in response to the action of acid. As a result, the acid-dissociable group dissociates due to the action of acid generated from the acid generator, etc., upon exposure, and the solubility of the polymer [A] in the developer in the exposed area changes, thereby forming a resist pattern.

[0046] As base (I), bases represented by the following formulas (I-1) to (I-3) (hereinafter also referred to as "bases (I-1) to bases (I-3)") are preferred. For example, in the following formula (I-1), -C(R 4 )(R 5 )(R 6 ) corresponds to an acid-dissociable group.

[0047] [ka]

[0048] In the above equations (I-1) to (I-3), * represents Ar in equation (1). 1 Or Ar 2 This shows the bonding site with Y. 1 These are -COO-, -O-, or -OCOO-.

[0049] In the above equation (I-1), R 4 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 5 and R 6 Each of these groups is either an independent monovalent hydrocarbon group having 1 to 20 carbon atoms, or part of an alicyclic structure with 3 to 20 member atoms formed by combining these groups with the carbon atoms to which they are bonded.

[0050] In the above equation (I-2), R 7 R is a hydrogen atom. 8 and R 9 Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. 10 R 7 , R 8 and R 9 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 structure with 4 to 20 ring members.

[0051] In the above equation (I-3), R 11 and R 12 Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R 13 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R 11 and R 12 These are combined with each other and together with the carbon atoms to which they are bonded, forming part of an alicyclic structure with 3 to 20 members, or R 12 and R 13 They are combined with each other R 12 The carbon atoms and R that are bonded to it 13 It is part of an aliphatic heterocyclic structure with 5 to 20 members, formed together with the oxygen atoms to which it is bonded.

[0052] Y 1 -COO- or -O- are preferred.

[0053] R 4 , R 5 , R 6 , R 8 , R 9 , R 11 , R 12 and R 13 A hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1) is, for example, R 2 and R 3 Examples include groups similar to the hydrocarbon groups exemplified above.

[0054] R 5 and R 6 or R 11 and R 12 Examples of alicyclic structures with 3 to 20 members, formed by combining these elements with the carbon atoms to which they bond, include monocyclic saturated alicyclic structures such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane structures; polycyclic saturated alicyclic structures such as norbornane and adamantane structures; monocyclic unsaturated alicyclic structures such as cyclopropene, cyclobutene, cyclopentene, and cyclohexene structures; and polycyclic unsaturated alicyclic structures such as norbornene structures.

[0055] R 10 As a divalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), for example, R 2 and R 3 Examples include groups obtained by removing one hydrogen atom from a monovalent hydrocarbon group, as illustrated above.

[0056] R 10 R 7 , R 8 and R 9 As an example of an unsaturated alicyclic structure with 4 to 20 ring members, formed together with the carbon atoms to which each is bonded, the above-mentioned R 5 and R 6 or R 11 and R 12Among the alicyclic structures having 3 to 20 ring members, which are aligned with each other and composed of carbon atoms to which they are bonded, examples of the unsaturated alicyclic structures include those having 4 to 20 ring members, which are the same as those exemplified above.

[0057] R 12 and R 13 are aligned with each other, and R 12 is bonded to the carbon atom and R 13 is bonded to the oxygen atom, and examples of the aliphatic heterocyclic structure having 5 to 20 ring members include saturated oxygen-containing heterocyclic structures such as oxacyclobutane structure, oxacyclopentane structure, and oxacyclohexane structure, and unsaturated oxygen-containing heterocyclic structures such as oxacyclobutene structure, oxacyclopentene structure, and oxacyclohexene structure.

[0058] R 4 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 or a phenyl group.

[0059] R 5 and R 6 is preferably a chain hydrocarbon group, more preferably an alkyl group or an alkenyl group, and even more preferably a methyl group or an ethenyl group. Also, R 5 and R 6 is preferably such that R 5 and R 6 is also preferably an alicyclic structure having 3 to 20 ring members, which is composed of the carbon atoms to which they are bonded and aligned with each other. As this alicyclic structure, a saturated alicyclic structure is preferable, a monocyclic saturated alicyclic structure or a polycyclic saturated alicyclic structure is more preferable, and a cyclopentane structure or an adamantane structure is even more preferable.

[0060] R 8 and R 9 is preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, even more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.

[0061] R<( 10 is R7 , R 8 and R 9 As an unsaturated alicyclic structure with 4 to 20 members, formed together with the carbon atoms to which each is bonded, a cyclohexene structure is preferred.

[0062] R 11 A hydrogen atom is preferred as the element.

[0063] R 12 and R 13 For example, R 12 and R 13 They are combined with each other R 12 The carbon atoms and R that are bonded to it 13 It is preferable that the structure is an aliphatic heterocyclic structure with 5 to 20 member atoms, and as this aliphatic heterocyclic structure, a saturated oxygen-containing heterocyclic structure is preferred, and an oxacyclohexane structure is more preferred.

[0064] Examples of base (I-1) include the bases represented by the following formulas (I-1-1) to (I-1-7) (hereinafter also referred to as "base (I-1-1) to base (I-1-7)").

[0065] [ka]

[0066] In equations (I-1-1) to (I-1-7) above, * is equivalent to equation (I-1) above.

[0067] Examples of base (I-2) include the base represented by the following formula (I-2-1) (hereinafter also referred to as "base (I-2-1)").

[0068] [ka]

[0069] In equation (I-2-1) above, * is equivalent to equation (I-2) above.

[0070] Examples of base (I-3) include the base represented by the following formula (I-3-1) (hereinafter also referred to as "base (I-3-1)").

[0071] [ka]

[0072] In equation (I-3-1) above, * is equivalent to equation (I-3) above.

[0073] As for group (I), group (I-1) and group (I-2) are preferred, with group (I-1) being more preferred.

[0074] (Group(II)) Group (II) is a group containing a polar group. Examples of polar groups include groups containing a lactone ring structure or a cyclic carbonate structure, groups that yield a hydroxyl group upon hydrolysis, fluorinated alcohol groups, ketone groups, and alkoxy groups.

[0075] Examples of base (II) include the base represented by the following formula (II-1) (hereinafter also referred to as "base (II-1)").

[0076] [ka]

[0077] In equation (II) above, * represents Ar in equation (1) above. 1 Or Ar 2 This shows the bonding site with Y. 2 R is a single bond, -COO-, or -O-. 14 This is the polar group described above.

[0078] Examples of group (II-1) include groups represented by the following formulas (II-1-1) to (II-1-7). The group represented by formula (II-1-1) is a specific example of a group in which the polar group contains a cyclic carbonate structure, the group represented by formula (II-1-2) is a specific example of a group in which the polar group contains a lactone ring structure, the group represented by formula (II-1-3) is a specific example of a group in which the polar group yields a hydroxyl group upon hydrolysis, the group represented by formula (II-1-4) is a specific example of a group in which the polar group is a fluorinated alcohol group, the group represented by formula (II-1-5) is a specific example of a group in which the polar group is a ketone group, and the group represented by formula (II-1-6) is a specific example of a group in which the polar group is an alkoxy group.

[0079] [ka]

[0080] In equations (II-1-1) to (II-1-7) above, * is equivalent to equation (II-1) above.

[0081] Preferred polar groups include groups containing a lactone ring structure or a cyclic carbonate structure, groups that yield a hydroxyl group upon hydrolysis, or fluorinated alcohol groups, with groups containing a lactone ring structure or a cyclic carbonate structure, or groups that yield a hydroxyl group upon hydrolysis, being more preferred.

[0082] The lower limit of the content of structural unit (I) in polymer [A] is preferably 1 mol%, and more preferably 5 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 60 mol%, and more preferably 50 mol%. By setting the content of structural unit (I) within the above range, the sensitivity to exposure light, LWR performance, and CDU performance of the radiation-sensitive resin composition can be further improved.

[0083] [Structural Units (II)] Structural unit (II) is a structural unit that contains an acid-dissociable group.

[0084] [A]When the polymer has structural unit (II), the acid-dissociable group of this structural unit (II) causes the polymer to exhibit a property where its solubility in the developer changes in response to the action of acid. As a result, the acid-dissociable group dissociates due to the action of acid generated from [B] acid generator, etc., upon exposure, and the solubility of the polymer in the developer in the exposed area changes, thereby forming a resist pattern.

[0085] Examples of structural unit (II) include the structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (II-1)"). Note that in the following formula (3), -C(R X )(R Y )(R Z ) corresponds to an acid-dissociable group.

[0086] [ka]

[0087] In the above equation (3), R T R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X R is a hydrogen atom or 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 an alicyclic structure with 3 to 20 member lengths formed by these groups together with the carbon atoms to which they are bonded. 1 It is a single bond or a divalent organic group having 1 to 20 carbon atoms.

[0088] R X , R Y or R Z As a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), for example, R 2 and R 3 Examples include groups similar to the hydrocarbon groups exemplified above.

[0089] R Yand R Z As an alicyclic structure with 3 to 20 members formed by combining these groups with the carbon atoms to which these groups are bonded, for example, in formula (2-1) above, R 5 and R 6 Examples include structures similar to those exemplified, which are alicyclic structures with 3 to 20 member numbers formed by combining these elements with the carbon atoms to which they bond.

[0090] L 1 As a divalent organic group having 1 to 20 carbon atoms represented by the above formula (1), for example, R 2 and R 3 Examples of organic groups with 1 to 20 carbon atoms in this context include groups obtained by removing one hydrogen atom from the groups exemplified above.

[0091] R T From the viewpoint of copolymerization of the monomer that gives structural unit (II), a hydrogen atom or a methyl group is preferred.

[0092] R X The group is preferably a chain-like hydrocarbon group or an aromatic hydrocarbon group, and more preferably an alkyl group or an aryl group. The aromatic hydrocarbon group may be substituted with a halogen atom.

[0093] R Y and R Z For example, it may be a chain hydrocarbon group or an alicyclic hydrocarbon group, or R Y and R Z It is preferable that these groups are combined with each other to form a saturated alicyclic structure together with the carbon atoms to which they are bonded.

[0094] L 1 Preferably, the group consists of a single bond or a combination of a divalent hydrocarbon group and a divalent heteroatom-containing group.

[0095] As structural unit (II), structural units represented by the following formulas (3-1) to (3-8) (hereinafter also referred to as "structural units (II-1) to (II-8)") are preferred.

[0096] [ka]

[0097] In the above equations (3-1) to (3-8), R T This is equivalent to equation (3) above.

[0098] [A] The lower limit of the content of structural unit (II) in polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%, relative to the total structural units constituting polymer [A]. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of structural unit (II) within the above range, the sensitivity to exposure light, LWR performance, and CDU performance of the radiation-sensitive resin composition can be further improved.

[0099] [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.

[0100] [A] The polymer further possesses structural unit (III), which enhances the hydrophilicity of the resist film, allows for appropriate adjustment of solubility in the developer, and improves the adhesion of the resist pattern to the substrate. Furthermore, when extreme ultraviolet (EUV) or electron beams are used as the radiation irradiated in the exposure step of the resist pattern formation method described later, the sensitivity to exposure light can be further improved. Therefore, this radiation-sensitive resin composition can be suitably used as a radiation-sensitive resin composition for extreme ultraviolet exposure or electron beam exposure.

[0101] Examples of structural units (III) include structural units represented by the following formula.

[0102] [ka]

[0103] In the above formula, R L3 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0104] [A]When polymer has structural unit (III), the lower limit of the content of structural unit (III) is preferably 20 mol%, and more preferably 30 mol%, relative to the total structural units in polymer [A]. The upper limit of the above content is preferably 80 mol%, and more preferably 70 mol%.

[0105] [Other structural units] Other structural units include, for example, structural units containing alcoholic hydroxyl groups (hereinafter also referred to as "structural unit (IV)"), lactone structures, cyclic carbonate structures, sultone structures, or combinations thereof (hereinafter also referred to as "structural unit (V)").

[0106] (Structural Unit (IV)) Structural unit (IV) is a structural unit containing an alcoholic hydroxyl group. By further including structural unit (IV), the solubility in the developer can be adjusted to a more appropriate degree, and as a result, the sensitivity of the radiation-sensitive resin composition to exposure light can be further improved.

[0107] Examples of structural units (IV) include structural units represented by the following formula.

[0108] [ka]

[0109] In the above formula, R L2 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0110] (Structural unit (V)) Structural unit (V) is a structural unit that includes a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. By further including structural unit (V), the solubility in the developer can be adjusted to a more appropriate degree.

[0111] Examples of structural units (V) include structural units represented by the following formula.

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] In the above formula, R L1 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0117] [A] If polymer has other structural units, the lower limit of the content of the other structural units 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%.

[0118] [A] The lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) of the polymer determined by gel permeation chromatography (GPC) is preferably 2,000, more preferably 3,000, and still more preferably 4,000. The upper limit of the above Mw is preferably 10,000, more preferably 9,000, and still more preferably 8,000. [A] By setting the Mw of the polymer within the above range, the solubility in the developer can be appropriately adjusted.

[0119] [A] The upper limit of the ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the polymer by GPC (Mw / Mn, hereinafter also referred to as "dispersion degree") is preferably 2.50, more preferably 2.00, and even more preferably 1.75. The lower limit of the above ratio is usually 1.00, preferably 1.10, and more preferably 1.20. [A] By setting the Mw / Mn of the polymer within the above range, the coating properties of the radiation-sensitive resin composition can be further improved.

[0120] The Mw and Mn values ​​of polymers in this specification are measured by gel permeation chromatography (GPC) under the following conditions. GPC columns: Two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column from Tosoh Corporation. Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0121] The lower limit of the content of the polymer in the radiation-sensitive resin composition is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and particularly preferably 80% by mass, relative to all components other than the organic solvent [D].

[0122] [A] Polymers can be synthesized, for example, by polymerizing monomers that give each structural unit using known methods.

[0123] [[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.

[0124] [B] Examples of acids generated from acid generators include sulfonic acids and imido acids.

[0125] [B] Examples of acid generators include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds.

[0126] Examples of onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0127] [B]Specific examples of acid generators include, for example, the compounds described in paragraphs

[0080] to

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

[0128] Examples of [B] acid generators that produce sulfonic acid upon exposure include compounds represented by the following formula (4) (hereinafter also referred to as "[B] compound"). In the following, T in formula (4) is used. + The monovalent, radiation-sensitive onium cation represented by is called an "onium cation," and the part other than this onium cation is called an "anion."

[0129] [ka]

[0130] In the above equation (4), 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, where n is an integer between 0 and 10. p1 +n p2 +n p3 n is between 1 and 30. 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.

[0131] R p1 Examples of monovalent groups containing ring structures with 5 or more members include monovalent groups containing alicyclic structures with 5 or more members, monovalent groups containing aliphatic heterocyclic structures with 5 or more members, monovalent groups containing aromatic carbocyclic structures with 6 or more members, and monovalent groups containing aromatic heterocyclic structures with 5 or more members.

[0132] Examples of alicyclic structures with five or more ring members include monocyclic saturated alicyclic structures such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and cyclododecane; monocyclic unsaturated alicyclic structures such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene; polycyclic saturated alicyclic structures such as norbornane, adamantane, tricyclodecane, and tetracyclododecane; and polycyclic unsaturated alicyclic structures such as norbornene and tricyclodecene.

[0133] Examples of aliphatic heterocyclic structures with five or more ring members include lactone structures such as hexanolactone and norbornanelactone, sultone structures such as hexanosultone and norbornanesultone, oxygen-containing heterocyclic structures such as oxacycloheptane and oxanorbornane, nitrogen-containing heterocyclic structures such as azacyclohexane and diazabicyclooctane, and sulfur-containing heterocyclic structures such as thiacyclohexane and thianorbornane.

[0134] Examples of aromatic carbocyclic structures with six or more members include benzene, naphthalene, phenanthrene, and anthracene structures.

[0135] Examples of aromatic heterocyclic structures with five or more members include oxygen-containing heterocyclic structures such as furan, pyran, benzofuran, and benzopyran structures, and nitrogen-containing heterocyclic structures such as pyridine, pyrimidine, and indole structures.

[0136] R p1The 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 to exposure light and LWR performance of the resist pattern formed by the radiation-sensitive resin composition can be further improved, and the process window can be further expanded.

[0137] R p1 Some or all of the hydrogen atoms in the ring structure may be substituted with substituents. Examples of substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine, as well as hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. Among these, hydroxyl groups, fluorine atoms, or iodine atoms are preferred.

[0138] R p1 Preferably, the group is a monovalent group containing an alicyclic structure with 5 or more members, a monovalent group containing an aromatic carbocyclic structure with 6 or more members, or a monovalent group containing an aliphatic heterocyclic structure with 5 or more members. More preferably, the group is a monovalent group containing a polycyclic saturated alicyclic structure, a monovalent group containing an aromatic carbocyclic structure with 6 or more members containing an iodine atom, a monovalent group containing an oxygen atom-containing heterocyclic structure, or a monovalent group containing a sulfur atom-containing heterocyclic structure.

[0139] R p2 Examples of divalent linking groups represented by include carbonyl groups, ether groups, carbonyloxy groups, sulfide groups, thiocarbonyl groups, sulfonyl groups, and divalent hydrocarbon groups. Among these, carbonyloxy groups, sulfonyl groups, alkanediyl groups, or divalent alicyclic saturated hydrocarbon groups are preferred, and carbonyloxy groups are more preferred.

[0140] R p3 and R p4Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R include alkyl groups having 1 to 20 carbon atoms. p3 and R p4 Examples of monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, represented by R, include fluorinated alkyl groups having 1 to 20 carbon atoms. p3 and R p4 Preferably, the element is a hydrogen atom, a fluorine atom, or a fluorinated alkyl group; more preferably, a hydrogen atom, a fluorine atom, or a perfluoroalkyl group; and even more preferably, a hydrogen atom, a fluorine atom, or a trifluoromethyl group.

[0141] R p5 and R p6 Examples of monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, 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.

[0142] n p1 Preferably, the value is 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0143] n p2 Preferably, the value is 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0144] 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.

[0145] n p1 +n p2 +n p3 The lower limit is preferably 2, and more preferably 4. p1 +n p2 +np3 The upper limit is preferably 20, and more preferably 10.

[0146] Examples of anions include those represented by the following formulas (4-1) to (4-13).

[0147] [ka]

[0148] T + Examples of monovalent radiosensitive onium cations represented by the formula (ra) to (rc) below include monovalent cations (hereinafter also referred to as "cations (ra) to (rc)").

[0149] [ka]

[0150] 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 B2 is 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 B4Each 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.

[0151] In the above equation (rb), b4 is an integer from 0 to 9. 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 10. 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 3 to 20 members, formed by these groups combined with the carbon atoms or carbon chains to which they are bonded. b3 R is an integer between 0 and 3. B8 This refers to a single bond or a divalent organic group having 1 to 20 carbon atoms. b2 This is an integer between 0 and 2.

[0152] In the above equation (rc), b6 is an integer from 0 to 5. When b6 is 1, R B9is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b6 is 2 or more, there are multiple R B9 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. b7 is an integer from 0 to 5. If b7 is 1, R B10 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. If b7 is 2 or more, there are multiple R B10 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.

[0153] R B1 , R B2 , R B3 , R B4 , R B5 , R B6 , R B7 , R B9 and R B10 Examples of monovalent organic groups having 1 to 20 carbon atoms represented by the above formula (2) include R 2 or R 3 Examples include groups similar to the monovalent organic group exemplified above.

[0154] R B8 Examples of divalent organic groups represented by the above formula (2) include R 2 or R 3 Examples include groups obtained by removing one hydrogen atom from the monovalent organic group exemplified above.

[0155] R B3 and R B4 Preferably, these are hydrogen atoms or single bonds formed by combining them.

[0156] b1 and b2 are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. b3 is preferably 0 to 4, more preferably 0 to 2, and even more preferably 0 or 1. b1 0 or 1 is preferred.

[0157] If b3 is 1 or greater, R B5 A cyclohexyl group or a cyclohexylsulfonyl group is preferred.

[0158] Examples of onium cations include those represented by the following formulas (ra-1) to (ra-9), (rb-1), and (rc-1).

[0159] [ka]

[0160] [B] As the acid generator, a compound obtained by appropriately combining the onium cation and the anion exemplified above can be used.

[0161] 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 even more preferably 10 parts by mass, per 100 parts by mass of the [A] polymer. The upper limit of the above content is preferably 80 parts by mass, more preferably 70 parts by mass, and even more preferably 60 parts by mass. By setting the content of the [B] acid generator within the above range, the sensitivity to exposure light, LWR performance, and CDU performance of the resist pattern formed by the radiation-sensitive resin composition can be further improved.

[0162] [[C] Acid diffusion control agent] [C] The acid diffusion control agent controls the diffusion phenomenon of acids generated from [B] acid generators, etc., in the resist film upon exposure, thereby controlling undesirable chemical reactions in non-exposed areas. By containing the [C] acid diffusion control agent, the radiation-sensitive resin composition can further improve its sensitivity to exposure light, LWR performance, and CDU performance. The radiation-sensitive resin composition may contain one or more [C] acid diffusion control agents.

[0163] [C] Examples of acid diffusion control agents include nitrogen atom-containing compounds and photodegradable bases that are photosensitive upon exposure and generate weak acids.

[0164] Examples of nitrogen atom-containing compounds include amine compounds such as tripentylamine and trioctylamine, amide group-containing compounds such as formamide and N,N-dimethylacetamide, urea compounds such as urea and 1,1-dimethylurea, and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine and Nt-pentyloxycarbonyl-4-hydroxypiperidine.

[0165] Examples of photodecayable bases include compounds containing an onium cation that decomposes upon exposure and a weak acid anion. In photodecayable bases, a weak acid is generated from the proton produced when the onium cation decomposes and from the weak acid anion in the exposed area, thus reducing the controllability of acid diffusion.

[0166] Examples of onium cations that decompose upon exposure include cations represented by the above formulas (ra) to (rc). Among these, triphenylsulfonium cation (cation (ra-1)), phenyldibenzothiophenium cation (cation (ra-4)), diphenyl(4-(cyclohexylsulfonyl)phenyl)sulfonium cation, tris(4-fluorophenyl)sulfonium cation (cation (ra-2)), or diphenyl(4-trifluoromethylphenyl)sulfonium cation (cation (ra-3)) are preferred.

[0167] Examples of the anion of the weak acid include an anion represented by the following formula.

[0168] [Chemical formula]

[0169] As the photodecomposable base, a compound obtained by appropriately combining an onium cation decomposed by the above exposure and an anion of the above weak acid can be used.

[0170] When the radiation-sensitive resin composition contains a [C] acid diffusion controller, the lower limit of the content of the [C] acid diffusion controller is preferably 0.5 parts by mass, more preferably 1 part by mass, still more preferably 5 parts by mass, and even more preferably 10 parts by mass with respect to 100 parts by mass of the [A] polymer. The upper limit of the above content is preferably 45 parts by mass, more preferably 40 parts by mass, still more preferably 35 parts by mass, and even more preferably 30 parts by mass. By setting the content of the [C] acid diffusion controller within the above range, the sensitivity to exposure light, LWR performance, and CDU performance of the resist pattern formed by the radiation-sensitive resin composition can be further improved.

[0171] [[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, if necessary, the [C] acid diffusion controller, [E] polymer, and other optional components.

[0172] Examples of the [D] organic solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, etc. The radiation-sensitive resin composition can contain one or more [D] organic solvents.

[0173] Examples of the alcohol 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-1-methyl ether.

[0174] Examples of the 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.

[0175] Examples of the 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.

[0176] Examples of the 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.

[0177] 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 acetate 1-monomethyl ether, polyhydric carboxylic acid diester solvents such as diethyl oxalate, and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

[0178] 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.

[0179] [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, monocarboxylic acid ester solvents, lactone-based solvents, polyhydric alcohol partial ether carboxylate solvents, or combinations thereof are more preferred, and propylene glycol 1-monomethyl ether, ethyl lactate, γ-butyrolactone, propylene glycol acetate 1-monomethyl ether, or combinations thereof are even more preferred.

[0180] 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.

[0181] [[E] Polymer] [E] polymer is a polymer with a higher mass content of fluorine atoms than [A] polymer. Generally, polymers with higher hydrophobicity than the base polymer tend to be concentrated on the surface of the resist film. Because [E] polymer has a higher mass content of fluorine atoms than [A] polymer, this hydrophobic property causes it to be concentrated on the surface of the resist film. As a result, when the radiation-sensitive resin composition contains [E] polymer, it is possible to suppress the elution of acid generators, acid diffusion control agents, etc., into the immersion medium during immersion exposure. Furthermore, when the radiation-sensitive resin composition contains [E] polymer, the hydrophobic property of [E] polymer allows the advancing contact angle between the resist film and the immersion medium to be controlled within a desired range, thereby suppressing the occurrence of bubble defects. Moreover, with this radiation-sensitive resin composition, the receding contact angle between the resist film and the immersion medium becomes larger, enabling high-speed scan exposure without the retention of water droplets. By further containing [E] polymer in this way, the radiation-sensitive resin composition can form a resist film suitable for immersion exposure. Furthermore, by containing the [E] polymer, the radiation-sensitive resin composition can form a resist pattern in which the occurrence of defects is suppressed.

[0182] The lower limit of the mass content of fluorine atoms in the [E] polymer is preferably 1% by mass, more preferably 2% by mass, and still more preferably 3% by mass. The upper limit of the above mass content is preferably 60% by mass, more preferably 50% by mass, and still more preferably 40% by mass. By setting the mass content of fluorine atoms within the above range, the segregation of the [E] polymer in the resist film can be adjusted more appropriately. Note that the mass content of fluorine atoms in the polymer is 13 The polymer structure can be determined by measuring the ¹³C NMR spectrum, and the calculation can be derived from that structure.

[0183] The form in which fluorine atoms are contained in the [E] polymer is not particularly limited and may be bonded to either the main chain or the side chains of the [E] polymer. Preferably, the [E] polymer has structural units containing fluorine atoms (hereinafter also referred to as "structural units (I')"). The [E] polymer may further have structural units other than the above structural units (I'). The [E] polymer may have one or more of each structural unit. The radiation-sensitive resin composition may contain one or more [E] polymers.

[0184] The following describes the various structural units of the [E] polymer.

[0185] (Structural unit (I')) Structural unit (I') is a structural unit that contains a fluorine atom. Examples of structural unit (I') include the structural unit represented by the following formula (f) (hereinafter also referred to as "structural unit (I'-1)").

[0186] [ka]

[0187] In the above equation (f), R f1 L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 R is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2NH-, -CONH-, or -OCONH-. f2 It is a monovalent organic group having 1 to 10 carbon atoms and containing a fluorine atom.

[0188] R f1 From the viewpoint of copolymerization of the monomer that gives the structural unit (I'-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0189] L 2 -COO- is preferred.

[0190] R f2Examples of the monovalent organic group having 1 to 10 carbon atoms and having a fluorine atom represented by the following include, for example, R in the above formula (1). 1 , R 2 or R 3 and groups similar to those exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by the following.

[0191] R f2 is preferably a fluorinated chain hydrocarbon group or a group in which some or all of the hydrogen atoms of this fluorinated chain hydrocarbon group are substituted with hydroxy groups.

[0192] As the structural unit (I'-1), a structural unit represented by the following formula is preferable.

[0193] [Chemical formula]

[0194] In the above formula, R f1 has the same meaning as the above formula (f).

[0195] When the [E] polymer has the structural unit (I'), the lower limit of the content ratio of the structural unit (I') is preferably 20 mol%, more preferably 30 mol%, and even more preferably 40 mol% with respect to all the structural units constituting the [E] polymer. The upper limit of the above content ratio is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%. By setting the content ratio of the structural unit (F) within the above range, the mass content ratio of the fluorine atoms in the [E] polymer can be further appropriately adjusted.

[0196] (Other structural units) Examples of other structural units include, for example, structural units having an acid dissociable group (hereinafter, also referred to as "structural unit (II')"). Examples of the structural unit (II') include structural units similar to those exemplified as the structural unit (II) of the above [A] polymer.

[0197] [E]When the polymer has structural unit (II'), the lower limit of the content of structural unit (II') is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the polymer. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%.

[0198] [E] The lower limit of Mw of the polymer determined by GPC is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 4,000. The upper limit of Mw is preferably 50,000, more preferably 20,000, even more preferably 10,000, and particularly preferably 8,000.

[0199] [E] The upper limit of the ratio of Mw to Mn (Mw / Mn) of the polymer determined by GPC is preferably 5.00, more preferably 3.00, even more preferably 2.50, and particularly preferably 2.00. The lower limit of the above ratio is usually 1.00, and preferably 1.20.

[0200] [E] polymers, like [A] polymers, can be synthesized, for example, by polymerizing monomers that give each structural unit using known methods.

[0201] If the radiation-sensitive resin composition contains an [E] polymer, the lower limit of the [E] polymer content is preferably 0.5 parts by mass, more preferably 1 part by mass, and still more preferably 2 parts by mass, per 100 parts by mass of the [A] polymer. The upper limit of the above content is preferably 20 parts by mass, more preferably 15 parts by mass, and still more preferably 10 parts by mass.

[0202] [Other optional components] Other optional components include, for example, surfactants. The radiation-sensitive resin composition may contain one or more other optional components.

[0203] [Method for preparing a radiation-sensitive resin composition] The radiation-sensitive resin composition can be prepared by mixing, for example, [A] polymer and [B] acid generator, and optionally [C] acid diffusion control agent, [D] organic solvent, [E] polymer and other optional components in predetermined proportions, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.2 μm or less.

[0204] <Method for forming a resist pattern> The resist pattern formation method comprises a step of directly or indirectly coating a substrate with a radiation-sensitive resin composition (hereinafter also referred to as the "coating step"), a step of exposing the resist film formed by the coating step (hereinafter also referred to as the "exposure step"), and a step of developing the exposed resist film (hereinafter also referred to as the "development step"). In the resist pattern formation method, the above-mentioned radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

[0205] According to this resist pattern formation method, by using the above-mentioned radiation-sensitive resin composition as the radiation-sensitive resin composition in the coating step, it is possible to form a resist pattern that has good sensitivity to exposure light and excellent LWR performance and CDU performance.

[0206] The following describes each step of the resist pattern formation method.

[0207] [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.

[0208] In this process, the above-mentioned radiation-sensitive resin composition is used as the radiation-sensitive resin composition.

[0209] Examples of substrates include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Furthermore, indirect application of the radiation-sensitive resin composition to the substrate can be in the form of application to an anti-reflective film formed on the substrate. Examples of such anti-reflective films include organic or inorganic anti-reflective films disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Publication No. 59-93448.

[0210] 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 lower 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.

[0211] [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 can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet (EUV), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha 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, and ArF excimer laser light, EUV, or electron beams are even more preferred.

[0212] After the exposure described above, it is preferable to perform a post-exposure bake (hereinafter also referred to as "PEB") to promote the dissociation of acid-dissociable groups of the [A] polymer, etc., by the acid generated from the [B] compound, etc., by exposure in the exposed portion of the resist film. This PEB can increase the difference in solubility in the developer between the exposed and unexposed portions. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°C, and even more preferably 100°C. The upper limit of the temperature is preferably 180°C, and more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and even more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and even more preferably 100 seconds.

[0213] [Development process] In this step, the exposed resist film is developed. This allows for the formation of a predetermined resist pattern. After development, it is common to wash the film with a rinsing solution such as water or alcohol and then dry it. The development method in the development step may be alkaline development or organic solvent development.

[0214] 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.

[0215] 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 one or more of the solvents exemplified as the [D] organic solvent in the above-mentioned radiation-sensitive resin composition. Among these, ester solvents or ketone solvents are preferred. As for ester solvents, ester acetate solvents are preferred, and n-butyl acetate is more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The lower limit of the content of organic solvents in the developer can be preferably 80% by mass, more preferably 90% by mass, even more preferably 95% by mass, and particularly preferably 99% by mass. Examples of components other than organic solvents in the developer can be water, silicone oil, etc.

[0216] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling up the developer solution on the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution onto a substrate rotating at a constant speed while scanning the developer solution dispensing nozzle at a constant speed (dynamic dispensing method).

[0217] Examples of patterns formed by this resist pattern formation method include line-and-space patterns and hole patterns. [Examples]

[0218] 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.

[0219] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), and degree of dispersion (Mw / Mn)] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using GPC columns from Tosoh Corporation (two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column) under the following conditions. Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0220] [Percentage of structural units] The content ratio of each structural unit in the polymer was determined using a nuclear magnetic resonance spectrometer (JEOL Ltd.'s "JNM-Delta400"). 13 It was measured by 13C-NMR analysis.

[0221] <[M]Synthesis of monomers> [M] Compounds represented by the following formulas (M-1) to (M-28) (hereinafter also referred to as "monomers (M-1) to (M-e)") were synthesized as monomers by the following method.

[0222] [ka]

[0223] [Synthesis Example 1] Synthesis of monomer (M-1) 50.00 g of 2,3,4,5,6-pentafluorobenzoic acid, 5.76 g of 4-dimethylaminopyridine, and 42.2 g of 2-methyl-3-buten-3-ol were weighed into a 1 L round-bottom flask and dissolved in 200 mL of tetrahydrofuran. The solution was cooled to 0°C, and 100 mL of a tetrahydrofuran solution of 55.6 g of N,N'-dicyclohexylcarbodiimide was added dropwise, followed by stirring at room temperature for 8 hours. After the reaction was complete, saturated aqueous ammonium chloride solution was added, and the mixture was extracted with ethyl acetate and concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain 59.4 g of the compound represented by the following formula (A) (hereinafter also referred to as "intermediate (A)"). The synthesis scheme of intermediate (A) is shown below.

[0224] [ka]

[0225] 12.29 g of p-hydroxybenzaldehyde and 28.2 g of intermediate (A) were weighed into a 1 L round-bottom flask and dissolved in 100 mL of N,N'-dimethylformamide. After cooling the solution to 0°C, 20.87 g of potassium carbonate was added over 30 minutes, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, saturated aqueous solution of ammonium chloride was added, and the mixture was extracted with ethyl acetate and concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain 36.3 g of the compound represented by the following formula (B) (hereinafter also referred to as "intermediate (B)"). The synthesis scheme of intermediate (B) is shown below.

[0226] [ka]

[0227] 22.9 g of zinc was weighed into a 500 mL round-bottom flask and dissolved in 95 mL of N,N'-dimethylformamide. The solution was heated to 50°C, and then 0.74 g of acetyl chloride was added dropwise and the mixture was stirred for 1 hour. Subsequently, a solution of 36.1 g of intermediate (B) in dibromomethane (24.6 g) was added dropwise, ensuring the temperature did not exceed 70°C, and the mixture was stirred at 50°C for 3 hours. After the reaction was complete, a saturated aqueous solution of ammonium chloride was added, and the mixture was extracted with ethyl acetate and concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain 23.7 g of monomer (M-1). The synthesis scheme for monomer (M-1) is shown below.

[0228] [ka]

[0229] [Synthesis Examples 2-22, 26-27] Synthesis of monomers (M-2)-(M-22) and (M-26)-(M-27) Monomers (M-2) to (M-22) and (M-26) to (M-27) were synthesized in the same manner as in Synthesis Example 1, except that the precursor was changed as appropriate.

[0230] [Synthesis Example 23] Synthesis of monomer (M-23) 10.0 g of 1,1'-thiobis(2-naphthol) and 6.35 g of triethylamine were weighed into a 500 mL round-bottom flask and mixed with 200 mL of dichloromethane. 6.35 g of methacrylic anhydride was added dropwise to the mixed solution, which had been stirred at room temperature, and the mixture was stirred further at room temperature for 3 hours. After the reaction was complete, saturated aqueous solution of ammonium chloride was added, and the mixture was extracted with dichloromethane and concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain 11.5 g of the compound represented by the following formula (C) (hereinafter also referred to as "intermediate (C)"). The synthesis scheme of intermediate (C) is shown below.

[0231] [ka]

[0232] 11.5 g of intermediate (C) was weighed into a 500 mL round-bottom flask and dissolved in 200 mL of tetrahydrofuran. To the solution, which had been stirred at room temperature, 2.83 g of pyridine and 2.81 g of acetyl chloride were added dropwise, and the mixture was stirred further at room temperature for 6 hours. After the reaction was complete, saturated aqueous solution of ammonium chloride was added, and the mixture was extracted with ethyl acetate and concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain 12.5 g of monomer (M-23). ​​The synthesis scheme for monomer (M-23) is shown below.

[0233] [ka]

[0234] [Synthesis Examples 24-25, 28] Synthesis of monomers (M-24)-(M-25), (M-28) Monomers (M-24) to (M-25) and (M-28) were synthesized in the same manner as in Synthesis Example 23, except that the precursor was changed as appropriate.

[0235] <Synthesis of polymers [A] and [E]> In the synthesis of polymers [A] and [E], compounds represented by the following formulas (M-29) to (M-55) (hereinafter also referred to as "monomers (M-29) to (M-55)") were used as monomers other than monomer [M]. In the following synthesis examples, unless otherwise specified, parts by mass means the value when the total mass of monomers used is 100 parts by mass, and mol% means the value when the total number of moles of monomers used is 100 mol%.

[0236] [ka]

[0237] [Synthesis Example 29] Synthesis of Polymer (A-1) Monomers (M-1), (M-44), and (M-46) were dissolved in 200 parts by mass of 1-methoxy-2-propanol in a molar ratio of 20 / 35 / 45. Next, 4 mol% of azobisisobutyronitrile (hereinafter also referred to as "AIBN") was added as an initiator to prepare the monomer solution. Meanwhile, 100 parts by mass of 1-methoxy-2-propanol 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, carrying out the polymerization reaction for a total of 6 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature.

[0238] 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, filtered again, 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 the hydrolysis reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass). The solid was added dropwise to 500 parts by mass of water to solidify the resin, and the obtained solid was filtered off. The mixture was dried at 50°C for 12 hours to obtain a white powdery polymer (A-1).

[0239] The Mw of polymer (A-1) was 5,500, and the Mw / Mn ratio was 1.44. Also, 13 1C-NMR analysis revealed that the content of each structural unit derived from monomers (M-1), (M-44), and (M-46) in polymer (A-1) was 21 mol%, 33 mol%, and 46 mol%, respectively.

[0240] [Synthesis Examples 30-54, 60-66] Synthesis of polymers (A-2)-(A-26), (A-32)-(A-36), (a-1), and (a-2) Polymers (A-2) to (A-26), (A-32) to (A-36), (a-1), and (a-2) were synthesized in the same manner as in Synthesis Example 29, except that the monomers used were of the types and proportions shown in Table 1 below. The Mw and Mw / Mn of each obtained polymer, as well as the content ratio of structural units derived from each monomer in each polymer, are also shown in Table 1 below.

[0241] [Synthesis Example 55] Synthesis of Polymer (A-27) Monomers (M-1), (M-29), and (M-35) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 35 / 20 / 45. Next, 2 mol% of AIBN was added as an initiator to prepare the monomer solution. Meanwhile, 100 parts by mass of 2-butanone was added to an empty reaction vessel and purged with nitrogen for 30 minutes. The reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to 2,000 parts by mass of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 400 parts by mass of methanol, filtered again, and dried at 60°C for 15 hours to obtain a white powdery polymer (A-27) in good yield.

[0242] The Mw of polymer (A-27) was 6,000, and the Mw / Mn ratio was 1.44. Also, 13 ¹¹C-NMR analysis revealed that the content of each structural unit derived from monomers (M-1), (M-29), and (M-35) in polymer (A-27) was 38 mol%, 16 mol%, and 46 mol%, respectively.

[0243] [Synthesis Examples 56-59] Synthesis of polymers (A-28)-(A-31) Polymers (A-28) to (A-31) were synthesized in the same manner as in Synthesis Example 55, except that the monomers used were of the types and proportions shown in Table 1 below. The Mw and Mw / Mn of each obtained polymer, as well as the content ratio of structural units derived from each monomer in each polymer, are also shown in Table 1 below.

[0244] In Table 1 below, "-" indicates that the corresponding ingredient was not used.

[0245] [Table 1]

[0246] [Synthesis Example 67] Synthesis of Polymer (E-1) Monomers (M-30) and (M-54) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 45 / 55. Next, 5 mol% of AIBN was added as an initiator to prepare the monomer solution. Meanwhile, 100 parts by mass of 2-butanone was added to an empty reaction vessel and purged with nitrogen for 30 minutes. The reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with 400 parts by mass of acetonitrile, and then 100 parts by mass of hexane was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of polymer (E-1) was obtained in good yield.

[0247] The Mw of polymer (E-1) was 5,600, and the Mw / Mn ratio was 1.69. Also, 13 1C-NMR analysis revealed that the content of each structural unit derived from monomers (M-30) and (M-54) in polymer (E-1) was 44 mol% and 56 mol%, respectively.

[0248] [Synthesis Example 68] Synthesis of Polymer (E-2) Polymer (E-2) was synthesized in the same manner as in Synthesis Example 67, except that the monomers used were of the types and proportions shown in Table 2 below. The Mw and Mw / Mn of the obtained polymer (E-2), as well as the content ratio of structural units derived from each monomer in polymer (E-2), are also shown in Table 2 below.

[0249] [Table 2]

[0250] <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 refers to the value when the mass of the [A] polymer used is 100 parts by mass.

[0251] [[B] Acid Generator] [B] Compounds represented by the following formulas (B-1) to (B-13) (hereinafter also referred to as "acid generators (B-1) to (B-13)") were used as acid generators.

[0252] [ka]

[0253] [[C] Acid diffusion control agent] [C] Compounds represented by the following formulas (C-1) to (C-8) (hereinafter also referred to as "acid diffusion control agents (C-1) to (C-8)") were used as acid diffusion control agents.

[0254] [ka]

[0255] [[D] Organic solvents] [D] The following (D-1) to (D-4) were used as organic solvents. (D-1): Propylene glycol acetate 1-monomethyl ether (D-2): Ethyl lactate (D-3): γ-Butyrolactone (D-4): Propylene glycol 1-monomethyl ether

[0256] [Example 1] Preparation of radiation-sensitive resin composition (J-1) A radiation-sensitive resin composition (J-1) was prepared by mixing [A] 100 parts by mass of (A-1) as a polymer, [B] 45 parts by mass of (B-4) as an acid generator, [C] 15 parts by mass of (C-1) as an acid diffusion control agent, [D] 4,280 parts by mass of (D-1) and 1,830 parts by mass of (D-4) as organic solvents, and [E] 3 parts by mass of (E-1) as a polymer, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0257] [Examples 2-36 and Comparative Examples 1-2] Preparation of radiation-sensitive resin compositions (J-2)-(J-36) and (CJ-1)-(CJ-2) Radiation-sensitive resin compositions (J-2) to (J-36) and (CJ-1) to (CJ-2) were prepared in the same manner as in Example 1, except that the components of the types and amounts shown in Table 3 below were used.

[0258] [Table 3]

[0259] <Resist pattern formation> On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition prepared above was applied to this base layer anti-reflective coating using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV lithography system (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass TMAH aqueous solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (32 nm line and space pattern).

[0260] <Rating> The sensitivity, LWR performance, and CDU performance of resist patterns formed using the above-mentioned radiation-sensitive resin composition were evaluated according to the method described below. The results are shown in Table 4 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0261] [sensitivity] In forming a resist pattern using the above radiation-sensitive resin composition, the exposure amount for forming a 32 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as Eop (unit: mJ / cm²). 2 The sensitivity was set to Eop at 35.0 mJ / cm². 2 The following conditions are considered "good": 35.0 mJ / cm² 2 If it exceeded this value, it was rated as "poor."

[0262] [LWR performance] The mask size was adjusted to form a 32nm line-and-space pattern by irradiating with the Eop exposure amount determined in the sensitivity evaluation above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. Line width variation was measured at a total of 50 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as the LWR (unit: nm). A smaller LWR value indicates less line jaggedness and better performance. LWR performance was evaluated as "good" if the LWR was 2.50nm or less, and "poor" if it exceeded 2.50nm.

[0263] [CDU performance] A resist pattern was formed by adjusting the mask size to create a pattern with 35 nm diameter holes and a 90 nm pitch using the Eop exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The average value of the hole diameters of 16 points measured in a 500 nm × 500 nm range was taken as the average hole diameter in that range. The average hole diameter was measured at a total of 500 points in an arbitrary 500 nm × 500 nm range, and the 1 sigma value was calculated from the distribution of these measurements, which was defined as CDU (unit: nm). A smaller CDU value indicates less variation in hole diameter over long periods and better performance. CDU performance was evaluated as "good" if the CDU was 2.00 nm or less, and "poor" if it exceeded 2.00 nm.

[0264] [Table 4]

[0265] As is clear from the results in Table 4, all of the radiation-sensitive resin compositions in the examples showed better sensitivity, LWR performance, and CDU performance compared to the radiation-sensitive resin compositions in the comparative examples. [Industrial applicability]

[0266] According to the radiation-sensitive resin composition and resist pattern formation method of the present invention, it is possible to form a resist pattern that exhibits good sensitivity to exposure light and has excellent LWR performance and CDU performance. Therefore, the radiation-sensitive resin composition and resist pattern formation method can be suitably used in the processing of semiconductor devices, which are expected to become increasingly miniaturized in the future.

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, Radiation-sensitive acid generator and A radiation-sensitive resin composition containing [a specific substance]. 【Chemistry 1】 (In formula (1), R １ is a hydrogen atom, a methyl group or a trifluoromethyl group. L is a single bond, -COO-, -O- or -CONH-. Ar １ is a group obtained by removing (m + 2) hydrogen atoms from an aromatic ring having 6 to 30 ring members. X is a single bond, -O-, -CH ２ -, -S-, -SO ２ -, -NR Ａ - or -CONH-. R Ａ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Ar ２ is a group obtained by removing (n + 1) hydrogen atoms from an aromatic ring having 6 to 30 ring members. R ２ and R ３ are each independently an organic group having 1 to 20 carbon atoms, a fluorine atom or an iodine atom. However, at least one of R ２ and R ３ is an organic group (x) having 1 to 20 carbon atoms, and at least one of R2 and R3 is a fluorine atom or an iodine atom. The above organic group (x) is a group represented by the following formula (I-1) or (I-2), a group containing a lactone ring structure or a cyclic carbonate structure, a fluorinated alcohol group or a ketone group. m is an integer from 0 to 10. When m is 2 or more, a plurality of R ２ are the same as or different from each other. n is an integer from 0 to 10. When n is 2 or more, a plurality of R ３ are the same as or different from each other. m + n is 1 or more.) 【Chemistry 2】 (In equations (I-1) to (I-2), * represents Ar in equation (1) above.) １ or Ar ２ This indicates the bonding site with Y. １ This is the COO. In formula (I-1), R ４ R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. ５ and R ６ Each of these groups is either an independent monovalent hydrocarbon group having 1 to 20 carbon atoms, or part of an alicyclic structure with 3 to 20 member atoms formed by combining these groups with the carbon atoms to which they are bonded. In formula (I-2), R ７ R is a hydrogen atom. ８ and R ９ Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １０ R ７ , R ８ and R ９ These are divalent hydrocarbon groups with 1 to 20 carbon atoms that, together with the carbon atoms they bond to, constitute an unsaturated alicyclic structure with 4 to 20 member numbers.

2. Ar １ and Ar ２ The radiation-sensitive resin composition according to claim 1, wherein the aromatic ring that provides the fragrance is an aromatic hydrocarbon ring.

3. A step of coating a substrate directly or indirectly with the radiation-sensitive resin composition according to either claim 1 or claim 2, A step of exposing the resist film formed by the above coating step, The process of developing the exposed resist film described above A resist pattern formation method comprising the following:

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