Radiation-sensitive resin composition and pattern forming method

Abstract

Provided is a radiation sensitive resin composition that can form a resist film having sufficient levels of sensitivity, CDU performance, and development residue-inhibiting properties when next generation technology is used. Also provided is a pattern formation method. Provided is a radiation sensitive resin composition that contains: a resin comprising a structural unit represented by formula (1); one or at least two onium salts comprising an organic acid anion part and an onium cation part; and a solvent, wherein at least a portion of the onium cation part in the onium salt comprises an aromatic ring structure having a fluorine atom. (In formula (1), R is a hydrogen atom, an alkyl group having 1-5 carbon atoms, or a halogenated alkyl group having 1-5 carbon atoms, Y1 is a divalent linking group, and X1 is an acid dissociating group.)

Description

[Technical Field]

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

[0002] Photolithography techniques using resist compositions are used to form fine circuits in semiconductor elements. A typical procedure involves, for example, exposing a coating of the resist composition to radiation through a mask pattern to generate an acid, which is then catalyzed by a reaction that causes a difference in the solubility of the resin in an alkaline or organic solvent-based developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] In the photolithography technology, pattern miniaturization is being promoted by using short-wavelength radiation such as ArF excimer lasers or by combining such radiation with liquid immersion lithography. As a next-generation technology, the use of even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is being considered, and resist materials containing acid generators with benzene rings that have improved absorption efficiency for such radiation are also being investigated (Japanese Patent Laid-Open Publication No. 2014-2359). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-2359 Summary of the Invention [Problem to be solved by the invention]

[0005] The next-generation technologies mentioned above also require resist performance that is equal to or better than conventional performance in terms of sensitivity, critical dimension uniformity (CDU) performance, which is an index of the uniformity of line width and hole diameter, and development residue suppression, which suppresses the generation of residue during development.

[0006] An object of the present invention is to provide a radiation-sensitive resin composition and a pattern forming method that are capable of forming a resist film that has sufficient levels of sensitivity, CDU performance, and development residue suppression even when next-generation technologies are applied. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0008] In one embodiment, the present invention provides A resin containing a structural unit represented by the following formula (1) (hereinafter also referred to as "structural unit (I)"), one or more onium salts containing an organic acid anion moiety and an onium cation moiety; Solvent and Contains The present invention relates to a radiation-sensitive resin composition, in which at least a part of the onium cation moieties in the onium salt contains an aromatic ring structure having a fluorine atom. [ka] (In the above formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Y 1 is a divalent linking group, and X 1 is an acid-dissociable group.

[0009] This radiation-sensitive resin composition allows the construction of a resist film that satisfies sensitivity, CDU performance, and development residue suppression. While the reason for this is unclear, it is presumed as follows: Fluorine atoms have extremely high absorption of radiation such as EUV with a wavelength of 13.5 nm, thereby enhancing the sensitivity of the radiation-sensitive resin composition. Furthermore, the aromatic ring structure containing a fluorine atom contained in the onium cation moiety enhances the water repellency of the resist film and suppresses intermixing between the resist film and the underlying film, thereby suppressing development residue. Furthermore, the acid-dissociable group contained in the structural unit (I) in the resin has a high probability of contact with the acid generated by exposure due to the degree of freedom provided by the linking group or ester bond, and therefore, acid dissociation reaction occurs easily. Therefore, the dissolution contrast between exposed and unexposed areas is enhanced, resulting in excellent pattern formability. It is presumed that these combined effects enable the above-mentioned resist performance to be achieved. The "aromatic ring structure having fluorine" includes not only a structure in which a fluorine atom is directly bonded to an aromatic ring structure, but also a structure in which a fluorine atom is bonded to an aromatic ring structure via another atom (for example, a structure in which a fluorine atom is bonded to a substituent bonded to an aromatic ring structure).

[0010] In another embodiment, the present invention provides a resist film production method, comprising: exposing the resist film to light; developing the exposed resist film with a developer; The present invention relates to a pattern forming method comprising the steps of:

[0011] In this pattern formation method, the radiation-sensitive resin composition, which is excellent in sensitivity, CDU performance, and suppression of development residues, is used, and therefore a high-quality resist pattern can be efficiently formed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0013] 《Radiation-sensitive resin composition》 The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as the "composition") contains a resin, one or more onium salts, and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired. By containing a specific resin and an onium salt, the radiation-sensitive resin composition can impart high levels of sensitivity, CDU performance, and development residue suppression to the resulting resist film.

[0014] <Resin> The resin is an aggregate of polymers containing the structural unit (I) (hereinafter, this resin is also referred to as the "base resin"). In addition to the structural unit (I), the base resin may also contain a structural unit having a phenolic hydroxyl group or a structural unit that provides a phenolic hydroxyl group upon the action of an acid (hereinafter, both are also referred to as the "structural unit (II)"), a structural unit (III) containing a lactone structure, etc. Each structural unit will be described below.

[0015] (Structural unit (I)) The structural unit (I) is represented by the following formula (1). [ka] (In the above formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Y 1 is a divalent linking group, and X 1 is an acid-dissociable group.

[0016] In the above formula (1), the alkyl group having 1 to 5 carbon atoms represented by R is preferably a linear or branched alkyl group, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.

[0017] In the above formula (1), examples of the halogenated alkyl group having 1 to 5 carbon atoms represented by R include groups in which some or all of the hydrogen atoms in the above alkyl group having 1 to 5 carbon atoms have been substituted with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom being particularly preferred.

[0018] Y 1 The divalent linking group is not particularly limited, but suitable examples include a divalent hydrocarbon group which may have a substituent, and a divalent linking group containing a hetero atom. The term "substituted" for a hydrocarbon group means that some or all of the hydrogen atoms in the hydrocarbon group have been substituted with substituents (groups or atoms other than hydrogen atoms). The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. An aliphatic hydrocarbon group means a hydrocarbon group that does not have aromaticity. The Y 1 The aliphatic hydrocarbon group as the divalent hydrocarbon group in may be saturated or unsaturated, and is usually preferably saturated. More specifically, the aliphatic hydrocarbon group may be a straight-chain or branched-chain aliphatic hydrocarbon group, or an aliphatic hydrocarbon group containing a ring in its structure.

[0019] The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. As the straight-chain aliphatic hydrocarbon group, a straight-chain alkylene group is preferred, and specific examples include a methylene group [-CH2-], an ethylene group [-(CH2)2-], a trimethylene group [-(CH2)3-], a tetramethylene group [-(CH2)4-], and a pentamethylene group [-(CH2)5-]. The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkyl alkylene groups such as alkylmethylene groups such as -CH(CH3)-, -CH(CH2CH3)-, -C(CH3)2-, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, and -C(CH2CH3)2-; alkylethylene groups such as -CH(CH3)CH2-, -CH(CH3)CH(CH3)-, -C(CH3)2CH2-, -CH(CH2CH3)CH2-, and -C(CH2CH3)2-CH2-; alkyl trimethylene groups such as -CH(CH3)CH2CH2- and -CH2CH(CH3)CH2-; and alkyl tetramethylene groups such as -CH(CH3)CH2CH2CH2- and -CH2CH(CH3)CH2CH2-. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms. The linear or branched aliphatic hydrocarbon group may or may not have a substituent.

[0020] Examples of the aliphatic hydrocarbon group containing a ring in its structure include an alicyclic hydrocarbon group (a group in which two hydrogen atoms have been removed from an aliphatic hydrocarbon ring), a group in which an alicyclic hydrocarbon group is bonded to the end of a straight-chain or branched-chain aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group is interposed in the middle of a straight-chain or branched-chain aliphatic hydrocarbon group. Examples of the straight-chain or branched-chain aliphatic hydrocarbon group include the same as those described above. The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms. The alicyclic hydrocarbon group may be polycyclic or monocyclic. The monocyclic alicyclic hydrocarbon group is preferably a group in which two hydrogen atoms have been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group in which two hydrogen atoms have been removed from a polycycloalkane, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. The alicyclic hydrocarbon group may or may not have a substituent.

[0021] The aromatic hydrocarbon group is a hydrocarbon group having an aromatic ring. The Y 1 The aromatic hydrocarbon group as a divalent hydrocarbon group in the formula (I) preferably has 3 to 30 carbon atoms, more preferably 5 to 30, even more preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 10. However, this carbon number does not include the number of carbon atoms in the substituent. Specific examples of the aromatic ring contained in the aromatic hydrocarbon group include aromatic hydrocarbon rings such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are substituted with heteroatoms; etc. Examples of the heteroatom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic hydrocarbon group include a group in which two hydrogen atoms have been removed from the aromatic hydrocarbon ring (an arylene group); a group in which one hydrogen atom of a group in which one hydrogen atom has been removed from the aromatic hydrocarbon ring (an aryl group) has been substituted with an alkylene group (for example, a group in which one further hydrogen atom has been removed from the aryl group in an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group); and the like. The number of carbon atoms in the alkylene group (the alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. The aromatic hydrocarbon group may or may not have a substituent.

[0022] The Y 1 The heteroatom in the "divalent linking group containing a heteroatom" is an atom other than a carbon atom or a hydrogen atom, and examples thereof include an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. Examples of the divalent linking group containing a hetero atom include -O-, -C(=O)-O-, -C(=O)-, -OC(=O)-O-, -C(=O)-NH-, -NH- (H may be substituted with a substituent such as an alkyl group, an acyl group, or an aryl group), -S-, -S(=O)2-, -S(=O)2-O-, -NH-C(=O)-, =N-, and groups represented by the general formula -Y 21 -OY 22 -, -[Y 21 -C(=O)-O] mp -Y 22 -or- Y 21 -OC(=O)-Y 22 -, wherein Y 21 and Y 22 are each independently a divalent hydrocarbon group which may have a substituent, O is an oxygen atom, and mp is an integer of 0 to 3. Y 1 When Y is -NH-, the H may be substituted with a substituent such as an alkyl group, an acyl group, or an aryl group (aromatic group). 21 and Y 22are each independently a divalent hydrocarbon group which may have a substituent. Examples of the divalent hydrocarbon group include the above-mentioned Y 1 Examples of the "divalent hydrocarbon group which may have a substituent" include the same as those exemplified above as the "divalent hydrocarbon group which may have a substituent." Y 21 As the alkyl group, a straight-chain aliphatic hydrocarbon group is preferred, a straight-chain alkylene group is more preferred, a straight-chain alkylene group having 1 to 5 carbon atoms is even more preferred, and a methylene group or ethylene group is particularly preferred. Y 22 As the alkyl group, a linear or branched aliphatic hydrocarbon group is preferred, and a methylene group, an ethylene group or an alkylmethylene group is more preferred. The divalent linking group containing a hetero atom is preferably a linear group having an oxygen atom as a hetero atom, for example, a group containing an ether bond or an ester bond, and 21 -OY 22 -, -[Y 21 -C(=O)-O] mp -Y 22 -or- Y 21 -OC(=O)-Y 22 A group represented by - is more preferred.

[0023] Among the above, Y 1 As the divalent linking group, a linear or branched alkylene group, a divalent alicyclic hydrocarbon group, or a divalent linking group containing a hetero atom is particularly preferred. Among these, a linear or branched alkylene group or a divalent linking group containing a hetero atom is preferred.

[0024] In the above formula (1), X 1 The acid-dissociable group represented by the formula (I) is a group having acid dissociability such that at least the bond between the acid-dissociable group and the atom adjacent to the acid-dissociable group can be cleaved by the action of an acid.

[0025] The acid-dissociable group is not particularly limited, and widely known examples include groups that form cyclic or chain-like tertiary alkyl esters with a carboxy group in (meth)acrylic acid or the like; and acetal-type acid-dissociable groups such as alkoxyalkyl groups. Here, "tertiary alkyl ester" refers to a structure in which the hydrogen atom of a carboxy group is substituted with a linear or cyclic alkyl group to form an ester, and the tertiary carbon atom of the linear or cyclic alkyl group is bonded to the terminal oxygen atom of the carbonyloxy group (-C(=O)-O-). When an acid acts on this tertiary alkyl ester, the bond between the oxygen atom and the tertiary carbon atom is cleaved, forming a carboxy group. The chain or cyclic alkyl group may have a substituent. Hereinafter, a group that is acid-dissociable by forming a tertiary alkyl ester with a carboxy group will be referred to as a "tertiary alkyl ester-type acid-dissociable group" for convenience.

[0026] Examples of the tertiary alkyl ester type acid-dissociable group include an aliphatic branched acid-dissociable group and an acid-dissociable group containing an aliphatic cyclic group. Here, "aliphatic branched" refers to a branched structure that does not have aromaticity. The structure of the "aliphatic branched acid-dissociable group" is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. Furthermore, the "hydrocarbon group" may be either saturated or unsaturated, but is usually preferably saturated. Examples of the aliphatic branched acid-dissociable group include -C(R 71 )(R 72 )(R 73 In the formula, R 71 ~R 73 are each independently a linear alkyl group having 1 to 5 carbon atoms. 71 )(R 72 )(R 73 ) preferably has 4 to 8 carbon atoms, and specific examples thereof include a tert-butyl group, a 2-methyl-2-butyl group, a 2-methyl-2-pentyl group, and a 3-methyl-3-pentyl group. A tert-butyl group is particularly preferred.

[0027] The term "aliphatic cyclic group" refers to a monocyclic or polycyclic group that does not have aromaticity. The aliphatic cyclic group in the "acid-dissociable group containing an aliphatic cyclic group" may or may not have a substituent. The basic ring structure of the aliphatic cyclic group excluding the substituents is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The hydrocarbon group may be either saturated or unsaturated, but is usually preferably saturated. The aliphatic cyclic group may be monocyclic or polycyclic. Examples of the aliphatic cyclic group include groups in which one or more hydrogen atoms have been removed from a monocycloalkane, and groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as a bicycloalkane, tricycloalkane, or tetracycloalkane. Some of the carbon atoms constituting the ring of these alicyclic hydrocarbon groups may be substituted with an ether bond (—O—).

[0028] Examples of the acid-dissociable group containing an aliphatic cyclic group include groups represented by the following formulae (1-1) to (1-9) and (2-1) to (2-6).

[0029] [ka] [In the formula, R 14 is an alkyl group, and g is an integer of 0 to 8.

[0030] [ka] [In the formula, R 15 and R 16 are each independently an alkyl group.

[0031] In formulas (1-1) to (1-9), R 14 The alkyl group may be linear, branched, or cyclic, and is preferably linear or branched. The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. The branched alkyl group preferably has 3 to 10 carbon atoms, and more preferably 3 to 5 carbon atoms. Examples of the cyclic alkyl group include the same groups as those mentioned above for the aliphatic cyclic group. g is preferably an integer of 0 to 3, more preferably an integer of 1 to 3, and further preferably 1 or 2. In formulas (2-1) to (2-6), R 15 ~R 16 The alkyl group of R 14 The alkyl groups are the same as those mentioned above. In the above formulas (1-1) to (1-9) and (2-1) to (2-6), some of the carbon atoms constituting the ring may be substituted with an ethereal oxygen atom (—O—). In addition, in the formulae (1-1) to (1-9) and (2-1) to (2-6), the hydrogen atoms bonded to the carbon atoms constituting the ring may be substituted with a substituent.

[0032] An "acetal-type acid-dissociable group" generally substitutes for a hydrogen atom at the end of an OH-containing polar group such as a carboxy group or a hydroxy group and bonds to an oxygen atom. When an acid acts on the acetal-type acid-dissociable group, the bond between the acetal-type acid-dissociable group and the oxygen atom to which the acetal-type acid-dissociable group is bonded is cleaved, forming an OH-containing polar group such as a carboxy group or a hydroxy group.

[0033] X in the above formula (1) 1 is preferably represented by the following formula (s1) or (s2), in addition to the above-mentioned acid-dissociable groups. [ka] (In the above formula (s1), Cy is an aliphatic cyclic group formed together with carbon atoms. Ra 01 ~Ra 03are each independently a hydrogen atom, a substituted or unsubstituted monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or an aliphatic cyclic structure formed by combining two or more of these, provided that the aliphatic cyclic structure does not form a crosslinked structure. In the above formula (s2), Cy has the same meaning as in formula (s1) above. Ra 04 is a substituted or unsubstituted aromatic hydrocarbon group. In the above formula, * indicates a bond to the oxygen atom.

[0034] The aliphatic cyclic group represented by Cy may be a monocyclic group or a polycyclic group. Examples of monocyclic aliphatic cyclic groups include groups in which one or more hydrogen atoms have been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples include cyclopentane and cyclohexane. Examples of polycyclic aliphatic cyclic groups include groups in which one or more hydrogen atoms have been removed from a polycycloalkane. Among these, monocyclic aliphatic cyclic groups are preferred, and groups in which one or more hydrogen atoms have been removed from cyclopentane or cyclohexane are more preferred.

[0035] Some or all of the hydrogen atoms in the aliphatic cyclic group may be substituted.

[0036] In formula (s1), Ra 01 ~Ra 03 In the formula (I), examples of the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms. Ra 01 ~Ra 03 In the above, examples of the monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms include a monocyclic aliphatic saturated hydrocarbon group and a polycyclic aliphatic saturated hydrocarbon group. Ra 01 ~Ra 03 Among these, a hydrogen atom is particularly preferred from the viewpoint of ease of synthesis of the monomer compound from which the structural unit (I) is derived.

[0037] The above Ra 01 ~Ra 03 The chain saturated hydrocarbon group or the aliphatic cyclic saturated hydrocarbon group represented by the formula (I) may or may not have a substituent.

[0038] The aliphatic cyclic group having no crosslinked structure represented by Cy in formula (s2) is the same as the aliphatic cyclic group represented by Cy in formula (s1).

[0039] In formula (s2), Ra 04 Examples of the aromatic hydrocarbon group in the formula include a group in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 5 to 30 carbon atoms. 04 is preferably a group in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, and most preferably a group in which one or more hydrogen atoms have been removed from benzene.

[0040] Specific examples of the acid-dissociable group represented by the formula (s1) are listed below, where * indicates a bond.

[0041] [ka]

[0042] [ka]

[0043] Specific examples of the acid-dissociable group represented by the formula (s2) are listed below, where * indicates a bond.

[0044] [ka]

[0045] Specific examples of the structural unit represented by the above formula (1) are shown below. α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] Specific examples of the structural unit (I) having an acid-dissociable group represented by the above formula (s1) or (s2) are shown below. α represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] Among the above examples, the structural unit (I) is preferably at least one selected from the group consisting of structural units represented by the above formulae (a1-3-13) to (a1-3-24), (a1-3-33) to (a1-3-34), (a01-1-01) to (a01-1-08), (s1-1) to (s1-4), and (s2-1) to (s1-6).

[0055] The content of the structural unit (I) in the resin (total content when multiple types of structural unit (I) are present) is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 30 mol % or more, based on all structural units constituting the resin. The content is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less. By setting the content of the structural unit (I) within the above range, the radiation-sensitive resin composition can achieve further improvements in sensitivity and CDU performance.

[0056] (Structural unit (II)) The structural unit (II) is a structural unit having a phenolic hydroxyl group or a structural unit that provides a phenolic hydroxyl group under the action of an acid. In the present invention, the phenolic hydroxyl group of the structural unit (II) also includes a phenolic hydroxyl group produced by deprotection under the action of an acid generated by exposure. By including the structural unit (II) in the resin, the solubility in a developer can be more appropriately adjusted, thereby further improving the sensitivity of the radiation-sensitive resin composition. Furthermore, when KrF excimer laser light, EUV, electron beams, or the like are used as radiation for irradiation in the exposure step of the resist pattern formation method, the structural unit (II) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This structure is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. The structural unit (II) is preferably represented by the following formula (2):

[0057] [ka] (In the above formula (2), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L CA is a single bond, -COO- * Or -O-. * is a bond on the aromatic ring side. R 101 is a protecting group that is deprotected by the action of a hydrogen atom or an acid. 101If there are multiple R 101 are the same or different from each other. R 102 R is a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. 102 If there are multiple R 102 are the same or different from each other. n3 is an integer from 0 to 2, m3 is an integer from 1 to 8, and m4 is an integer from 0 to 8, provided that 1≦m3+m4≦2n3+5 is satisfied.

[0058] Above R α From the viewpoint of copolymerizability of the monomer that gives the structural unit (II), it is preferable that the alkyl group is a hydrogen atom or a methyl group.

[0059] L CA As the group, a single bond or -COO- * is preferred.

[0060] Above R 101 The protecting group that can be deprotected by the action of an acid represented by the formula (1) is X 1 The acid-dissociable groups are the same as those mentioned above.

[0061] R 102Examples of the alkyl group in the formula (I) include linear or branched alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, and propyl. Examples of the fluorinated alkyl group include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms, such as trifluoromethyl and pentafluoroethyl. Examples of the alkoxycarbonyloxy group include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethyloxycarbonyloxy. Examples of the acyl group include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, benzoyl, and acryloyl. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as acetyloxy, propionyloxy, benzoyloxy, and acryloyloxy.

[0062] The above n3 is more preferably 0 or 1, and even more preferably 0.

[0063] The above m3 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0064] The above m4 is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0065] The structural unit (II) is preferably a structural unit represented by the following formulas (2a-1) to (2a-10) (hereinafter also referred to as "structural unit (2a-1) to structural unit (2a-10)").

[0066] [ka]

[0067] In the above formulas (2a-1) to (2a-10), R α is the same as the above formula (2).

[0068] Among these, the above structural units (2a-1) to (2a-4), (2a-6), (2a-8) and (2a-9) are preferred.

[0069] The content of the structural unit (II) (total content when multiple types of structural unit (II) are present) is preferably 5 mol% or more, more preferably 8 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more, based on all structural units constituting the resin. The content is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and particularly preferably 30 mol% or less. By setting the content of the structural unit (II) within the above range, the radiation-sensitive resin composition can achieve further improvements in sensitivity and CDU performance.

[0070] When a monomer having a phenolic hydroxyl group, such as hydroxystyrene, is polymerized, it is preferred that the phenolic hydroxyl group is protected with a protecting group, such as an alkali-dissociable group, and then the polymer is polymerized in that state, and then hydrolyzed to remove the protection group, thereby obtaining the structural unit (II).

[0071] (Structural unit (III)) The structural unit (III) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further including the structural unit (III), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Furthermore, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0072] Examples of the structural unit (III) include structural units represented by the following formulae (T-1) to (T-10).

[0073] [ka]

[0074] In the above formula, RL1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5 and may be combined together to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0075] Above R L4 and R L5 The divalent alicyclic group having 3 to 8 carbon atoms formed by combining together with the carbon atoms to which they are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a fused alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that a fused alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0076] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0077] Of these, the structural unit (III) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0078] The content of the structural unit (III) (total content when multiple types of structural unit (III) are present) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units constituting the base resin. The content is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less. By ensuring that the content of the structural unit (III) falls within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0079] (other structural units) The base resin may optionally contain other structural units in addition to the structural units (I) to (III), such as a structural unit (IV) containing a polar group (excluding those corresponding to the structural units (II) and (III)) and another structural unit (V) containing an acid-dissociable group (excluding those corresponding to the structural unit (I)).

[0080] (Structural unit (IV)) The base resin further contains the structural unit (IV), which allows for adjustment of the solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0081] Examples of the structural unit (IV) include structural units represented by the following formula:

[0082] [ka]

[0083] In the above formula, R Ais a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0084] When the base resin has the structural unit (IV), the lower limit of the content of the structural unit (IV) (total content when multiple structural units (IV) are present) is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%, based on all structural units constituting the base resin. The upper limit of this content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By ensuring that the content of the structural unit (IV) falls within the above range, the lithography performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0085] (Structural unit (V)) The structural unit (V) is a structural unit containing an acid-dissociable group (however, it is different from the structural unit (I) and the structural unit (II)). The structural unit (V) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (V-1)") is preferred.

[0086] [ka]

[0087] In the above formula (3), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0088] Above R 7 From the viewpoint of copolymerizability of the monomer that gives the structural unit (V-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0089] Above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0090] Above R 8 ~R 10 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0091] Above R 8 ~R 10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula include a monocyclic or polycyclic saturated hydrocarbon group, and a monocyclic or polycyclic unsaturated hydrocarbon group.

[0092] Above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (I) include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0093] Above R 8 As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 5 carbon atoms, a linear or branched unsaturated hydrocarbon group having 1 to 5 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms is preferred.

[0094] Above R 9 and R 10 The divalent alicyclic group having 3 to 20 carbon atoms formed by combining the groups represented by the following formula with each other and the carbon atoms to which they are bonded may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group.

[0095] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure.

[0096] Examples of the structural unit (V-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (V-1-1) to (V-1-6)").

[0097] [ka]

[0098] In the above formulas (3-1) to (3-6), R 7 ~R 10 has the same meaning as in the above formula (3). i and j each independently represent an integer of 1 to 4. k and l are 0 or 1.

[0099] i and j are preferably 1. 8 R is preferably a methyl group, an ethyl group, or an isopropyl group. 9 and R 10 As the alkyl group, a methyl group or an ethyl group is preferred.

[0100] The base resin may contain one type of structural unit (V) or a combination of two or more types.

[0101] When the base resin contains the structural unit (V), the lower limit of the content of the structural unit (V) (the total content when multiple types are contained) relative to all structural units constituting the base resin is preferably 3 mol%, more preferably 5 mol%, and even more preferably 10 mol%. The upper limit of the content is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By keeping the content of the structural unit (V) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0102] (Method of synthesizing resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a known radical polymerization initiator or the like.

[0103] The molecular weight of the base resin is not particularly limited, but the lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (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 30,000, even more preferably 15,000, and particularly preferably 12,000. When the Mw of the resin is within the above range, the heat resistance and developability of the resulting resist film are good.

[0104] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0105] The method for measuring Mw and Mn of the resin in this specification is as described in the Examples.

[0106] The resin content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0107] <Other resins> The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.

[0108] The high-fluorine content resin preferably has, for example, the structural units (I) to (V) of the base resin, either singly or in combination, as needed, and also has a structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit (VI)"). [ka]

[0109] In the above formula (6), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. R 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0110] When the high-fluorine-content resin has the structural unit (VI), the lower limit of the content of the structural unit (VI) is preferably 50 mol%, more preferably 60 mol%, even more preferably 70 mol%, and particularly preferably 80 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of the content is preferably 100 mol%, more preferably 98 mol%, and even more preferably 95 mol%. By setting the content of the structural unit (VI) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, thereby further promoting uneven distribution of fluorine atoms in the surface layer of the resist film.

[0111] The high-fluorine-content resin may have, in addition to the structural unit (VI), (x) an alkali-soluble group or (y) a structural unit having a group that dissociates under the action of an alkali to increase the solubility in an alkaline developer (hereinafter also referred to as structural unit (VII)). By having the structural unit (VII), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0112] When the high-fluorine-content resin has the structural unit (VII), the lower limit of the content of the structural unit (VII) is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of the content is preferably 90 mol%, more preferably 75 mol%, and even more preferably 60 mol%. By setting the content of the structural unit (VII) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0113] The lower limit of the content of the high-fluorine content resin is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 1.5 parts by mass, relative to 100 parts by mass of the base resin, and the upper limit of the content is preferably 12 parts by mass, more preferably 10 parts by mass, even more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0114] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0115] <Onium salt> The onium salt is a component that contains an organic acid anion moiety and an onium cation moiety and generates an acid upon exposure. When at least a part of the onium cation moiety in the onium salt contains an aromatic ring structure having a fluorine atom, it is possible to achieve high sensitivity and suppress development residues due to improved acid generation efficiency.

[0116] Although the form of the onium salt contained in the radiation-sensitive resin composition is not particularly limited, it is preferable that the onium salt be at least one selected from the group consisting of a radiation-sensitive acid generator containing the organic acid anion moiety and the onium cation moiety, and an acid diffusion controller containing the organic acid anion moiety and the onium cation moiety and generating an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation. The differences in their functions are explained below.

[0117] The acid generated by exposure of an onium salt is thought to have two functions in the radiation-sensitive resin composition, depending on the strength of the acid. The first function is to dissociate the acid-dissociable group of a structural unit of the resin containing the acid-dissociable group, thereby generating a carboxyl group or the like. An onium salt having this first function is called a radiation-sensitive acid generator. The second function is to inhibit the diffusion of the acid generated from the radiation-sensitive acid generator in unexposed areas by salt exchange without substantially dissociating the acid-dissociable group of the resin under pattern formation conditions using the radiation-sensitive resin composition. An onium salt having this second function is called an acid diffusion controller. The acid generated from the acid diffusion controller can be said to be a relatively weaker acid (having a higher pKa) than the acid generated from the radiation-sensitive acid generator. Whether an onium salt functions as a radiation-sensitive acid generator or an acid diffusion controller is determined by the energy required to dissociate the acid-dissociable group of the resin and the acidity of the onium salt. The radiation-sensitive acid generator is preferably contained in the radiation-sensitive resin composition in a form in which the onium salt structure exists alone as a (low molecular weight) compound.

[0118] When the radiation-sensitive resin composition contains the radiation-sensitive acid generator, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of development with an aqueous alkaline solution, while becoming poorly soluble in the developer in the case of development with an organic solvent.

[0119] Furthermore, by including the acid diffusion controller in the radiation-sensitive resin composition, it is possible to suppress the diffusion of acid in unexposed areas, and to form a resist pattern that is superior in pattern developability and CDU performance.

[0120] In the radiation-sensitive resin composition, at least one of the organic acid anion moiety in the radiation-sensitive acid generator and the organic acid anion moiety in the acid diffusion controller preferably contains an iodine-substituted aromatic ring structure. Iodine atoms have a very high absorption of radiation such as EUV with a wavelength of 13.5 nm, thereby enhancing sensitivity. Furthermore, when the organic acid anion moiety of the onium salt contains an iodine-substituted aromatic ring structure, acid diffusion can be controlled by the molecular weight of the iodine atom, thereby improving CDU performance. When the organic acid anion moiety of the onium salt contains an iodine-substituted aromatic ring structure, the iodine-substituted aromatic ring structure and the aromatic ring structure having a fluorine atom may be present in the same compound or in different compounds.

[0121] Regardless of the onium salt's incorporation form, the organic acid anion portion preferably has at least one anion selected from the group consisting of sulfonate anions, carboxylate anions, and sulfonimide anions. The onium cation preferably has at least one anion selected from the group consisting of sulfonium cations and iodonium cations. The onium salt can efficiently exhibit the above-described functions by combining these structures.

[0122] The acid generated upon exposure includes those which generate sulfonic acid, carboxylic acid, and sulfonimide upon exposure, corresponding to the above organic acid anions.

[0123] For example, the onium salt that gives a sulfonic acid upon exposure is (1) A compound having one or more fluorine atoms or fluorinated hydrocarbon groups bonded to a carbon atom adjacent to a sulfonate anion, (2) Compounds in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom adjacent to the sulfonate anion Examples include:

[0124] Examples of onium salts that give carboxylic acids upon exposure include: (3) A compound having one or more fluorine atoms or fluorinated hydrocarbon groups bonded to a carbon atom adjacent to a carboxylate anion. (4) Compounds in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom adjacent to the carboxylate anion Examples include:

[0125] Among these, the radiation-sensitive acid generator is preferably one that corresponds to the above-mentioned (1), and the acid diffusion controller is preferably one that corresponds to the above-mentioned (2), (3), or (4), with (2) or (4) being particularly preferred.

[0126] <Radiation-sensitive acid generator> The onium salt as the radiation-sensitive acid generator contains an organic acid anion moiety and an onium cation moiety. The radiation-sensitive acid generator is preferably represented by the following formula (A-1) or (A-2).

[0127] [ka]

[0128] In formulas (A-1) and (A-2), L 1 is a single bond, an ether bond or an ester bond, or an alkylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The alkylene group may be linear, branched or cyclic.

[0129] R 1 is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or is an alkyl group having 1 to 20 carbon atoms, an alkoxy ...carbonyl group having 2 to 10 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, or an alkylsulfonyloxy group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group, or an alkoxy group having 1 to 10 carbon atoms, or -NR 8 -C(=O)-R 9 or -NR 8-C(=O)-OR 9 and R 8 is a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms which may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms, or an acyloxy group having 2 to 6 carbon atoms, and R 9 is an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms, or an acyloxy group having 2 to 6 carbon atoms. The alkyl group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, and alkenyl group may be linear, branched, or cyclic.

[0130] Of these, R 1 Examples include hydroxy groups, -NR 8 -C(=O)-R 9 , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like are preferred.

[0131] R 2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and represents a trivalent or tetravalent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0132] Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group. 3 and Rf 4 are preferably both fluorine atoms.

[0133] R 3 , R 4 , R 5 , R 6 and R 7R are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 3 , R 4 and R 5 contains one or more fluorine atoms, and R 6 and R 7 contains one or more fluorine atoms. 3 , R 4 and R 5 Any two of the above may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 2 to 12 carbon atoms, alkynyl groups having 2 to 12 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with hydroxy groups, carboxy groups, halogen atoms, cyano groups, amide groups, nitro groups, mercapto groups, sultone groups, sulfone groups, or sulfonium salt-containing groups, and some of the carbon atoms in these groups may be substituted with ether bonds, ester bonds, carbonyl groups, carbonate groups, or sulfonate ester bonds.

[0134] p is an integer that satisfies 1≦p≦3. q and r are integers that satisfy 0≦q≦5, 0≦r≦3, and 0≦q+r≦5. q is preferably an integer that satisfies 1≦q≦3, more preferably 2 or 3. r is preferably an integer that satisfies 0≦r≦2.

[0135] Examples of the organic acid anion moiety of the radiation-sensitive acid generator represented by the above formulas (A-1) and (A-2) include, but are not limited to, the following: All of the following are organic acid anion moieties having an iodine-substituted aromatic ring structure, but as organic acid anion moieties not having an iodine-substituted aromatic ring structure, structures in which the iodine atom in the following formula is substituted with an atom or group other than an iodine atom, such as a hydrogen atom or other substituent, can be suitably used.

[0136] [ka]

[0137]

change

[0138]

change

[0139]

change

[0140]

change

[0141]

change

[0142]

change

[0143]

change

[0144]

change

[0145]

change

[0146]

change

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] The onium cation moiety in the radiation-sensitive acid generator represented by formula (A-1) above is preferably represented by formula (Q-1) below.

[0151] [ka]

[0152] In the above formula (Q-1), Ra1 and Ra2 each independently represent a substituent. n1 represents an integer of 0 to 5, and when n1 is 2 or greater, multiple Ra1s may be the same or different. n2 represents an integer of 0 to 5, and when n2 is 2 or greater, multiple Ra2s may be the same or different. n3 represents an integer of 0 to 5, and when n3 is 2 or greater, multiple Ra3s may be the same or different. Ra3 represents a fluorine atom or a group having one or more fluorine atoms. Ra1 and Ra2 may be bonded to each other to form a ring. When n1 is 2 or greater, multiple Ra1s may be bonded to each other to form a ring. When n2 is 2 or greater, multiple Ra2s may be bonded to each other to form a ring.

[0153] The substituents represented by Ra1 and Ra2 are preferably an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a hydroxyl group, a halogen atom, or a halogenated hydrocarbon group.

[0154] The alkyl groups of Ra1 and Ra2 may be linear or branched alkyl groups. The alkyl groups preferably have 1 to 10 carbon atoms, and particularly preferably methyl, ethyl, n-butyl, and t-butyl groups.

[0155] The cycloalkyl group of Ra1 and Ra2 includes a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms), of which a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group are particularly preferred.

[0156] Examples of the alkyl group moiety of the alkoxy group of Ra1 and Ra2 include those previously listed as the alkyl group of Ra1 and Ra2. As the alkoxy group, a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group are particularly preferred.

[0157] Examples of the cycloalkyl group moiety of the cycloalkyloxy group of Ra1 and Ra2 include those previously listed as the cycloalkyl groups of Ra1 and Ra2. As this cycloalkyloxy group, a cyclopentyloxy group and a cyclohexyloxy group are particularly preferred.

[0158] Examples of the alkoxy group moiety of the alkoxycarbonyl group of Ra1 and Ra2 include those previously listed as the alkoxy groups of Ra1 and Ra2. As the alkoxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl group, and an n-butoxycarbonyl group are particularly preferred.

[0159] Examples of the alkyl group moiety of the alkylsulfonyl group of Ra1 and Ra2 include those previously listed as the alkyl groups of Ra1 and Ra2. Furthermore, examples of the cycloalkyl group moiety of the cycloalkylsulfonyl group of Ra1 and Ra2 include those previously listed as the cycloalkyl groups of Ra1 and Ra2. Particularly preferred examples of these alkylsulfonyl groups or cycloalkylsulfonyl groups include a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, a cyclopentanesulfonyl group, and a cyclohexanesulfonyl group.

[0160] Each of the groups Ra1 and Ra2 may further have a substituent, such as a halogen atom such as a fluorine atom (preferably a fluorine atom), a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, a cycloalkyloxy group, an alkoxyalkyl group, a cycloalkyloxyalkyl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, an alkoxycarbonyloxy group, and a cycloalkyloxycarbonyloxy group.

[0161] Examples of the halogen atom for Ra1 and Ra2 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom being preferred.

[0162] The halogenated hydrocarbon groups of Ra1 and Ra2 are preferably halogenated alkyl groups. Examples of the alkyl groups and halogen atoms constituting the halogenated alkyl groups are the same as those described above. Among these, fluorinated alkyl groups are preferred, and CF3 is more preferred.

[0163] As described above, Ra1 and Ra2 may be linked to each other to form a ring (i.e., a heterocycle containing a sulfur atom). In this case, Ra1 and Ra2 preferably form a single bond or a divalent linking group. Examples of the divalent linking group include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, an alkylene group, a cycloalkylene group, an alkenylene group, or a combination of two or more of these, and preferably have a total carbon number of 20 or less. Furthermore, when n1 is 2 or more, multiple Ra1s may be linked to each other to form a ring, and when n2 is 2 or more, multiple Ra2s may be linked to each other to form a ring. An example of such a ring is when two Ra1s are linked to each other to form a naphthalene ring together with the benzene ring to which they are bonded.

[0164] Ra3 is a fluorine atom or a group having a fluorine atom. Examples of the group having a fluorine atom include groups in which the alkyl group, cycloalkyl group, alkoxy group, cycloalkyloxy group, alkoxycarbonyl group, and alkylsulfonyl group represented by Ra1 and Ra2 are substituted with a fluorine atom. Among these, fluorinated alkyl groups are preferred, such as CF3, C2F5, C3F7, C4F9, and C5F 11 , C6F 13 , C7F 15 , C8F 17 , CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9 and CH2CH2C4F9 are more preferred, and CF3 is particularly preferred.

[0165] Ra3 is preferably a fluorine atom or CF3, more preferably a fluorine atom.

[0166] n1 and n2 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2.

[0167] n3 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0168] (n1+n2+n3) is preferably an integer of 1 to 15, more preferably an integer of 1 to 9, still more preferably an integer of 2 to 6, and particularly preferably an integer of 3 to 6. When (n1+n2+n3) is 1, it is preferable that n3=1 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 2, it is preferable that n1=n3=1 and Ra1 and Ra3 are each independently a fluorine atom or CF3, and that n3=2 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 3, it is preferable that n1=n2=n3=1 and Ra1 to Ra3 are each independently a fluorine atom or CF3.

[0169] Specific examples of such onium cation moieties represented by the above formula (Q-1) include the following: All of the following are sulfonium cation moieties containing an aromatic ring structure having a fluorine atom, but as onium cation moieties that do not contain an aromatic ring structure having a fluorine atom, structures in which the fluorine atom or CF3 in the following formula is substituted with an atom or group other than a fluorine atom, such as a hydrogen atom or other substituent, can be suitably used.

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] When the onium cation moiety in the radiation-sensitive acid generator represented by formula (A-2) contains an aromatic ring structure having a fluorine atom, the onium cation moiety is preferably a diaryliodonium cation having one or more fluorine atoms.

[0174] Specific examples of such onium cation moieties include the following: All of the following are iodonium cation moieties containing an aromatic ring structure having a fluorine atom, but as onium cation moieties that do not contain an aromatic ring structure having a fluorine atom, structures in which the fluorine atom or CF3 in the following formula is substituted with an atom or group other than a fluorine atom, such as a hydrogen atom or other substituent, can be suitably used.

[0175] [ka]

[0176] The radiation-sensitive acid generators represented by the formulas (A-1) and (A-2) can be synthesized by known methods, particularly by salt exchange reaction. Known radiation-sensitive acid generators can also be used as long as they do not impair the effects of the present invention.

[0177] These radiation-sensitive acid generators may be used alone or in combination of two or more. The lower limit of the content of the radiation-sensitive acid generator is preferably 0.5 parts by mass, more preferably 1 part by mass, even more preferably 2 parts by mass, and particularly preferably 4 parts by mass, relative to 100 parts by mass of the base resin. The upper limit of the content is preferably 20 parts by mass, more preferably 18 parts by mass, even more preferably 15 parts by mass, and particularly preferably 12 parts by mass. This allows for excellent sensitivity and CDU performance to be exhibited during resist pattern formation.

[0178] <Acid diffusion control agent> The onium salt as the acid diffusion controller contains an organic acid anion moiety and an onium cation moiety, and upon irradiation with radiation, generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator. The acid diffusion controller is preferably represented by the following formula (S-1) or (S-2):

[0179] [ka]

[0180] In formulas (S-1) and (S-2), R 1 represents a hydrogen atom, a hydroxy group, a fluorine atom, a chlorine atom, an amino group, a nitro group, a cyano group, or an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, or an alkylsulfonyloxy group having 1 to 4 carbon atoms, which may be substituted with a halogen atom, or -NR 1A -C(=O)-R 1B or -NR 1A -C(=O)-OR 1B R 1A is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 1B is an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.

[0181] R 3 , R 4 , R 5 , R 6 and R 7 R are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 3 , R 4 and R 5 is preferably a monovalent hydrocarbon group containing one or more fluorine atoms or groups having fluorine atoms, and R 6 and R 7 is preferably a monovalent hydrocarbon group containing one or more fluorine atoms or groups having fluorine atoms. 3 , R 4 and R 5 Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 2 to 12 carbon atoms, alkynyl groups having 2 to 12 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms. In addition, some or all of the hydrogen atoms in these groups may be substituted with substituents.

[0182] L 1is a single bond or a divalent linking group having 1 to 20 carbon atoms, which may contain an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, or a carboxy group.

[0183] m and n are integers that satisfy 0≦m≦5, 0≦n≦3, and 0≦m+n≦5, but are preferably integers that satisfy 1≦m≦3 and 0≦n≦2.

[0184] Examples of anions of the acid diffusion controller represented by the above formula (S-1) or (S-2) include, but are not limited to, those shown below. Note that all of the following are organic acid anion moieties having an iodine-substituted aromatic ring structure, but as organic acid anion moieties not having an iodine-substituted aromatic ring structure, structures in which the iodine atom in the following formula is substituted with an atom or group other than an iodine atom, such as a hydrogen atom or other substituent, can be suitably used.

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] As the onium cation moiety in the acid diffusion controller represented by the above formulas (S-1) and (S-2), the onium cation moiety in the radiation-sensitive acid generator can be suitably used.

[0191] The acid diffusion controllers represented by the formulas (S-1) and (S-2) can be synthesized by known methods, particularly salt exchange reactions. Known acid diffusion controllers can also be used as long as they do not impair the effects of the present invention. Furthermore, the acid diffusion controllers of this embodiment also include those in which the organic acid anion moiety and the onium cation moiety share the same aromatic ring structure.

[0192] These acid diffusion controllers may be used alone or in combination of two or more. The lower limit of the content of the acid diffusion controller is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 1.5 parts by mass, per 100 parts by mass of the base resin. The upper limit of the content is preferably 15 parts by mass, more preferably 12 parts by mass, and even more preferably 8 parts by mass. This allows for excellent sensitivity and CDU performance to be achieved during resist pattern formation.

[0193] (Structure of other organic acid anion moieties (1)) The radiation-sensitive acid generator (including both a radiation-sensitive strong acid generator and an acid diffusion controller) may contain, as the organic acid anion moiety, a structure represented by the following formula (bd1), in addition to or in place of the organic acid anion moiety of the radiation-sensitive strong acid generator represented by the above formula (A-1) or (A-2) or the organic acid anion moiety of the acid diffusion controller represented by the above formula (S-1) or (S-2).

[0194] [ka]

[0195] In the above formula (bd1), R x1 ~R x4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining two or more of these together. R y1 ~R y2 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining with each other. [ka] is a double bond or a single bond. R z1 ~R z4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining two or more of these together, provided that R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 At least one of them has an acid anion structure.

[0196] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The hydrocarbon groups in each of the above may be aliphatic hydrocarbon groups or aromatic hydrocarbon groups, and may be cyclic hydrocarbon groups or chain hydrocarbon groups. For example, R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 In the formula (I), examples of the hydrocarbon group which may have a substituent include a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, and a chain alkenyl group which may have a substituent.

[0197] The cyclic group which may have a substituent is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group which does not have aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated. Furthermore, Rx1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The cyclic hydrocarbon group in may contain a heteroatom, such as a heterocyclic ring.

[0198] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The aromatic hydrocarbon group in the formula (I) is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, even more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbon atoms. However, the carbon number does not include the number of carbon atoms in the substituent.

[0199] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 Specific examples of the aromatic ring contained in the aromatic hydrocarbon group in the formula (I) include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which some of the carbon atoms constituting these aromatic rings have been substituted with heteroatoms.

[0200] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 Specific examples of the aromatic hydrocarbon group in the above formula include groups in which one hydrogen atom has been removed from the aromatic ring.

[0201] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4The cyclic aliphatic hydrocarbon group in the above formula (1) includes an aliphatic hydrocarbon group containing a ring in its structure. Examples of the aliphatic hydrocarbon group containing a ring in its structure include an alicyclic hydrocarbon group (a group in which one hydrogen atom has been removed from an aliphatic hydrocarbon ring), a group in which an alicyclic hydrocarbon group is bonded to the end of a straight-chain or branched-chain aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group is interposed in the middle of a straight-chain or branched-chain aliphatic hydrocarbon group.

[0202] The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably has 3 to 12 carbon atoms.

[0203] The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group.

[0204] Among them, R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The cyclic aliphatic hydrocarbon group in is preferably a group in which one or more hydrogen atoms have been removed from a monocycloalkane or polycycloalkane.

[0205] The linear aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

[0206] The branched aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, even more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

[0207] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4Examples of the substituent in the cyclic group include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a nitro group, and a carbonyl group.

[0208] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The chain alkyl group may be either a straight chain or a branched chain.

[0209] The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms.

[0210] The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms.

[0211] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The chain alkenyl group may be either linear or branched, and preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbon atoms, and particularly preferably 3 carbon atoms.

[0212] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 Examples of the substituent in the chain alkyl or alkenyl group include an alkoxy group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, and the above-mentioned R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4Examples of the cyclic groups include the cyclic groups shown in the formula:

[0213] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 Of the above hydrocarbon groups, the hydrocarbon group in is preferably a cyclic group which may have a substituent, or a chain alkyl group which may have a substituent.

[0214] In the formula (bd1), R y1 ~R y2 may be bonded to each other to form a ring structure. This ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. In addition, this ring structure may be a polycyclic structure formed with other ring structures.

[0215] R y1 ~R y2 The alicyclic hydrocarbon formed by the above may be polycyclic or monocyclic. As the monocyclic alicyclic hydrocarbon, a monocycloalkane is preferred. As the polycyclic alicyclic hydrocarbon, a polycycloalkane is preferred.

[0216] R y1 ~R y2 Examples of the aromatic hydrocarbon ring formed by include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which some of the carbon atoms constituting these aromatic rings are substituted with heteroatoms.

[0217] R y1 ~R y2 The ring structure (alicyclic hydrocarbon, aromatic hydrocarbon) formed by may have a substituent. The substituent here may be any of the above-mentioned R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The substituents are the same as those in the cyclic group of the formula (I).

[0218] Ry1 ~R y2 The ring structure formed by the formula (I) is more preferably an aromatic hydrocarbon which may have a substituent, from the viewpoints of shortening the diffusion of the acid generated by exposure and controlling the diffusion of the acid.

[0219] In the formula (bd1), R z1 ~R z4 Two or more of R may be bonded to each other to form a ring structure. For example, R z1 is R z2 ~R z4 The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon.

[0220] R z1 ~R z4 The alicyclic hydrocarbon formed by two or more of these may be polycyclic or monocyclic. As the monocyclic alicyclic hydrocarbon, a monocycloalkane is preferred. As the polycyclic alicyclic hydrocarbon, a polycycloalkane is preferred.

[0221] R z1 ~R z4 Examples of aromatic hydrocarbon rings formed by two or more of the above include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which some of the carbon atoms constituting these aromatic rings are substituted with heteroatoms.

[0222] R z1 ~R z4 The ring structure (alicyclic hydrocarbon, aromatic hydrocarbon) formed by may have a substituent.

[0223] In the formula (bd1), R x1 ~R x4 Two or more of R may be bonded to each other to form a ring structure. For example, R x1 is R x2 ~R x4 The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon.

[0224] R x1 ~R x4 The alicyclic hydrocarbon formed by two or more of these may be polycyclic or monocyclic. As the monocyclic alicyclic hydrocarbon, a monocycloalkane is preferred. As the polycyclic alicyclic hydrocarbon, a polycycloalkane is preferred.

[0225] R x1 ~R x4 Examples of the aromatic hydrocarbon ring formed by two of these include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and aromatic heterocycles in which some of the carbon atoms constituting these aromatic rings are substituted with heteroatoms.

[0226] R x1 ~R x4 The ring structure (alicyclic hydrocarbon, aromatic hydrocarbon) formed by may have a substituent.

[0227] R x1 ~R x4 The ring structure formed by two or more of the above is preferably an alicyclic hydrocarbon from the viewpoint of controlling the diffusion of the acid.

[0228] In the formula (bd1), R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 At least one of the above has an acid anion structure, and the organic acid anion moiety as a whole forms an n-valent anion, where n is an integer of 1 or greater. By selecting the acid anion structure within the molecule, the organic acid anion moiety represented by formula (bd1) can function in the composition as a radiation-sensitive strong acid generator that generates an acid that acts on acid-dissociable groups in the base resin, or as an acid diffusion controller that traps the acid (controls the diffusion of the acid) generated from the radiation-sensitive strong acid generator upon exposure.

[0229] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4Examples of the acid anion structure include those having a sulfonate anion structure, a carboxylate anion structure, an imide anion structure, a methide anion structure, a carbonate anion structure, a borate anion structure, a halogen anion structure, a phosphate anion structure, an antimonate anion structure, an arsenate anion structure, etc. Among these, those having a sulfonate anion structure and those having a carboxylate anion structure are preferred.

[0230] In the organic anion moiety represented by the above formula (bd1), R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 R may each have the acid anion structure. x1 ~R x4 When two or more of R are bonded to each other to form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to this carbon atom may be substituted with the acid anion structure. y1 ~R y2 and R z1 ~R z4 The same is true for .

[0231] Specific examples of the organic anion moiety represented by the above formula (bd1) include, but are not limited to, those shown below.

[0232] [ka]

[0233] [ka]

[0234] (Structure of other organic acid anion moieties (2)) Examples of the structure of the other organic acid anion moiety include the structure (1) of the other organic acid anion moiety and the structure represented by the following formula (b1). [ka] (In the above formula (b1), R b1 is a monovalent hydrocarbon group having a steroid skeleton and having 17 to 50 carbon atoms. Y b1 is a divalent linking group containing a heteroatom or a single bond. V b1 is an alkylene group, a fluorinated alkylene group, or a single bond. R fa and R fb are each independently a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. Z b1 is the acid anion structure.)

[0235] In the formula (b1), R b1 represents a monovalent hydrocarbon group having a steroid skeleton and having 17 to 50 carbon atoms. The steroid skeleton may have a substituent. Here, the term "steroid skeleton" refers to a ring structure represented by the following chemical formula (St), in which three six-membered rings and one five-membered ring are fused together.

[0236] [ka]

[0237] In the above formula (St), the numbers adjacent to the carbon atoms indicate the carbon numbers. In this specification, when referring to the positions of carbon atoms in the steroid skeleton, the carbon numbers shown in the above formula (St) will be used.

[0238] R b1 The steroid skeleton of the monovalent hydrocarbon group in R preferably has at least one hydroxyl group. b1 In the steroid skeleton of the formula (St), at least one hydrogen atom in the ring structure represented by the formula (St) is preferably substituted with a hydroxyl group.

[0239] When the steroid skeleton has hydroxyl groups, the number of hydroxyl groups is not particularly limited and may be 1 to 10, 1 to 5, or 1 to 3. The number of hydroxyl groups is preferably 1 to 3, more preferably 2 or 3, and even more preferably 3.

[0240] R b1 The steroid skeleton of may contain a substituent other than a hydroxyl group. For example, the ring structure represented by the above chemical formula (St) may have a substituent such as an alkyl group, a carboxy group, an oxo group (=O), an alkoxy group, an alkylcarbonyloxy group, a formyloxy group (HC(=O)-O-), or a lactone-containing cyclic group bonded thereto.

[0241] R b1 When the steroid skeleton in formula (I) has an alkyl group as a substituent, the position of the alkyl group is not particularly limited, and examples thereof include the 10th, 13th, and 17th positions. The alkyl groups are preferably present at the 10th and 13th positions.

[0242] R b1 When the steroid skeleton in formula (I) has a substituent other than an alkyl group or a hydroxyl group, the position of the substituent is not particularly limited, and examples thereof include positions 3, 7, and 12. For example, the substituent may be present at one or two of positions 3, 7, and 12. Furthermore, when the substituent is a lactone-containing cyclic group, it may be present at position 17.

[0243] R b1 has 17 to 50 carbon atoms, preferably 17 to 40 carbon atoms, more preferably 17 to 30 carbon atoms, and particularly preferably 17 to 22 carbon atoms. In addition, R here b1 The number of carbon atoms includes the carbon atoms constituting the steroid skeleton, and also includes the carbon atoms in the substituents bonded to the steroid skeleton.

[0244] R b1 As the formula (R b1 -1)~(R b1In addition, when enantiomers or diastereomers exist, the following formulas represent and include these stereoisomers.

[0245] [ka]

[0246] [Formula(R b1 -1) Medium, R S11 , R S12 and R S13 each independently represents a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group that contains a heteroatom. b1 -2) Medium, R S21 and R S22 R are each independently a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group that contains a heteroatom. S23 represents an alkyl group which may contain a heteroatom. b1 -3) Medium, R S31 , R S32 and R S33 R each independently represents a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group that contains a hetero atom. S34 represents a lactone-containing cyclic group. * represents Y in formula (b1). b1 represents a bond to the atom.]

[0247] The formula (R b1 -1) Medium, R S11 ~R S13 In the formula (R), examples of the substituent containing a hetero atom other than a hydroxyl group include a carboxy group, an oxo group (=O), an alkoxy group, an alkylcarbonyloxy group, and a formyloxy group (HC(=O)-O-). b1 -2) Medium, R S21 and R S22 The same applies to the substituents other than the hydroxyl group containing hetero atoms in the formula (R b1 -3) Medium, R S31 ~R S33The same applies to substituents other than the hydroxyl group containing hetero atoms in the above formula (I).

[0248] Formula (R b1 -1) Medium, R S11 ~R S13 At least one of R is preferably a hydroxyl group. S11 ~R S13 Preferably, two or more of R are hydroxyl groups. S1 ~R S13 It is more preferable that all of R are hydroxyl groups. S11 ~R S13 Among these, it is preferable that the one that is not a hydroxyl group is a hydrogen atom.

[0249] Formula (R b1 -2) Medium, R S21 and R S22 At least one of R is preferably a hydroxyl group. S21 and R S22 Preferably, both R are hydroxyl groups. S21 and R S22 Among these, it is preferable that the one that is not a hydroxyl group is a hydrogen atom. Formula (R b1 -2) Medium, R S23 represents an alkyl group which may contain a heteroatom. The alkyl group may be linear or branched. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms.

[0250] The formula (R b1 -3) Medium, R S31 ~R S13 At least one of R is preferably a hydroxyl group. S31 ~R S33 Preferably, two or more of R are hydroxyl groups. S3 ~R S33 It is more preferable that all of R are hydroxyl groups. S31 ~R S33 Among these, it is preferable that the one that is not a hydroxyl group is a hydrogen atom.

[0251] Among them, R b1 is the formula (Rb1 A group represented by -1) is more preferred.

[0252] R b1 Specific examples of the formula (b1) are shown below, but are not limited to these. In the formula (b1), * indicates Y b1 indicates the bond bonded to

[0253] [ka]

[0254] [ka]

[0255] [ka]

[0256] Among the above, R b1 is preferably a group represented by the formulae (Rb-1-1) to (Rb-1-19), and more preferably a group represented by the formulae (Rb-1-1) to (Rb-1-7).

[0257] In the formula (b1), R fa and R fb are each independently a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms.

[0258] In the formula (b1), Y b1 represents a divalent linking group containing a hetero atom or a single bond. Y b1 The divalent linking group containing a hetero atom in the formula (1) is preferably Y 1 Examples of the divalent linking group containing a hetero atom include the same as those exemplified above for the divalent linking group containing a hetero atom.

[0259] Y b1 As the linking group, a divalent linking group containing an ester bond or an ether bond is preferred.

[0260] In the above formula (b1), Vb1 represents an alkylene group, a fluorinated alkylene group, or a single bond. V b1 The alkylene group or fluorinated alkylene group in may be linear or branched, but is preferably linear. b1 The alkylene group or fluorinated alkylene group in the formula (I) preferably has 1 to 4 carbon atoms, and more preferably has 1 to 3 carbon atoms.

[0261] Z b1 The acid anion structure represented by the formula (bd1) is x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The acid anion structure represented by the following formula can be preferably employed.

[0262] Specific examples of the organic acid anion moiety represented by the above formula (b1) are listed below, but the organic acid anion moiety is not limited to these specific examples. In the formula, k and k' each independently represent an integer of 0 to 5, and k'' represents an integer of 1 to 5. Note that all of the organic acid anion moieties shown below have a sulfonate anion, but structures in which the sulfonate anion is replaced with a carboxylate anion can also be suitably employed. When the organic acid anion moiety has a carboxylate anion, fluorine atoms do not need to be bonded to the carbon atoms at the α- and β-positions of the carboxylate anion.

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] The organic acid anion moiety represented by the above formula (b1) is preferably represented by the following formula (b1-an1): Note that, although the organic acid anion moiety shown below has a sulfonate anion, a structure in which the sulfonate anion is replaced with a carboxylate anion can also be suitably employed: When the organic acid anion moiety has a carboxylate anion, fluorine atoms do not need to be bonded to the carbon atoms at the α- and β-positions of the carboxylate anion.

[0268] [ka] [In the formula, R S11 ~R S13 is represented by the general formula (R b1 -1) is the same as in V b11 represents a single bond, -CHF- or -CF2-. k represents an integer of 1 to 5.

[0269] In the formula (b1-an1), R S11 ~R S13 is represented by the general formula (R b1 -1) is the same as in

[0270] <Solvent> The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the onium salt and base resin (at least one of the radiation-sensitive acid-generating resin and the resin), as well as optional additives.

[0271] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0272] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples of suitable polyhydric alcohol solvents include partially etherified polyhydric alcohol solvents in which some of the hydroxy groups of the above polyhydric alcohol solvents have been etherified.

[0273] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples of the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

[0274] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0275] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0276] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of the solvent include polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0277] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0278] Among these, alcohol-based solvents, ester-based solvents, and ketone-based solvents are preferred, monoalcohol-based solvents, polyhydric alcohol partial ether acetate-based solvents, polycarboxylic acid diester-based solvents, cyclic ketone-based solvents, and lactone-based solvents are more preferred, and diacetone alcohol, propylene glycol monomethyl ether acetate, ethyl lactate, cyclohexanone, and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0279] <Other optional ingredients> The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0280] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing an onium salt, a base resin (at least one of a radiation-sensitive acid-generating resin and a resin), a solvent, and, if necessary, other optional components in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.2 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0281] <<Pattern Forming Method>> The pattern forming method in this embodiment includes: a step (1) of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); A step (2) of exposing the resist film to light (hereinafter also referred to as the "exposure step"); and The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0282] According to the pattern formation method, a high-quality resist pattern can be formed because the radiation-sensitive resin composition is used, which has excellent sensitivity and CDU performance in the exposure step and excellent suppression of development residues in the development step. Each step will be described below.

[0283] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, and preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0284] When performing immersion exposure, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0285] Furthermore, when the next step, the exposure step, is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (I) to (IV), and optionally the structural unit (V), as the base resin in the composition.

[0286] [Exposure process] In this step (step (2) above), the resist film formed in step (1), the resist film formation step, is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). The radiation used for exposure may be, depending on the line width of the desired pattern, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), X-rays, and gamma rays; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0287] When the exposure is carried out by immersion exposure, examples of the immersion liquid to be used include water and fluorine-based inert liquids.

[0288] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the resin or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0289] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0290] In the case of alkaline development, the developer used for the development may be, for example, an alkaline aqueous solution 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 (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0291] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing organic solvents. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As the ketone solvent, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0292] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which developer is sprayed onto the surface of the substrate (spray method), and a method in which developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispensing nozzle is scanned at a constant speed (dynamic dispense method). [Example]

[0293] The present invention will be specifically explained below with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples. Measurement methods for various physical properties are shown below.

[0294] [Mw and Mn] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Eluent: tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) 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

[0295] The structures of the sulfonium salt or iodonium salt radiation-sensitive acid generators PAG1 to PAG13 used in the radiation-sensitive resin compositions of the examples are shown below.

[0296] [ka]

[0297] [ka]

[0298] [Synthesis Example] Synthesis of base polymers (P-1) to (P-9) Each monomer was combined and copolymerized in tetrahydrofuran (THF) solvent, crystallized in methanol, and then repeatedly washed with hexane, isolated, and dried to obtain base polymers (P-1) to (P-9) with the following compositions. 1Mw and dispersity (Mw / Mn) were confirmed by H-NMR and the above-mentioned GPC (solvent: THF, standard: polystyrene). P-1: Mw=7,700, Mw / Mn=1.7 P-2: Mw=8.000, Mw / Mn=1.7 P-3: Mw=8,200, Mw / Mn=1.7 P-4: Mw=7,600, Mw / Mn=1.7 P-5: Mw=7,500, Mw / Mn=1.7 P-6: Mw=7,900, Mw / Mn=1.7 P-7: Mw=7,600, Mw / Mn=1.7 P-8: Mw = 8,000, Mw / Mn = 1.8 P-9: Mw=7,100, Mw / Mn=1.6

[0299] [ka]

[0300] [ka]

[0301] [Examples and Comparative Examples] Each component was dissolved in a solvent containing 100 ppm of FC-4430 (manufactured by 3M) as a surfactant, in the composition shown in Table 1. The resulting solution was filtered through a 0.2 μm filter to prepare a radiation-sensitive resin composition.

[0302] In Table 1, the components are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone) CHN (cyclohexanone) PGME (Propylene Glycol Monomethyl Ether) DAA (diacetone alcohol) EL (Ethyl lactate)

[0303] Acid diffusion control agents (Q-1) to (Q-5) [ka]

[0304] High fluorine content resin F-1: Mw=8,900, Mw / Mn=2.0 [ka]

[0305] [Evaluation of sensitivity by EUV exposure] A 12-inch silicon wafer was coated with a composition for forming a bottom antireflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") and then heated at 205°C for 60 seconds to form a bottom antireflective coating with an average thickness of 105 nm. Each radiation-sensitive resin composition listed in Table 1 was coated onto this bottom antireflective coating using the spin coater, followed by PB at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was exposed to light using an EUV scanner (ASML's "NXE3300" (NA 0.33, σ 0.9 / 0.6, quadrupole pole illumination, 46 nm pitch on wafer, +20% bias hole pattern mask)). PEB was performed on a hot plate at 120°C for 60 seconds, and development was performed in a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to form a resist pattern with 23 nm holes and a 46 nm pitch. The exposure dose to form this resist pattern with 23 nm holes and a 46 nm pitch was defined as the optimum exposure dose (Eop), and the optimum exposure dose was defined as the sensitivity (mJ / cm 2 ) was decided.

[0306] [CDU evaluation] A resist pattern with 23 nm holes and a 46 nm pitch was formed using the exposure dose determined above and the same procedure as above. The formed resist pattern was observed from above using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000"). The hole diameter was measured at 16 points within a 500 nm range and the average value was calculated. The average value was also measured at 500 arbitrary points. A 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was used as the evaluation value (nm) of CDU performance. The smaller the evaluation value, the smaller the variation in hole diameter over a long period, and the better the CDU performance. The results are shown in Table 1.

[0307] [Evaluation of development residue] A wafer with a resist film formed thereon was prepared by performing the same operations as described above up to the step of forming a resist film with an average thickness of 55 nm. Next, without performing pattern exposure using an EUV scanner, PEB was performed on a hot plate at 120°C for 60 seconds. Next, development was performed for 30 seconds in a 2.38 mass% TMAH aqueous solution, rinsed for 30 seconds in pure water, and dried. In this way, a wafer for evaluation of development residue was prepared. This wafer was observed using a defect inspection system COMPLUS (manufactured by AMAT), and the presence or absence of residual defects was confirmed using a defect review SEM RS5500 (manufactured by Hitachi High-Technologies Corporation), and the number of residual defects was counted. Evaluation was performed using the following index according to the number of residual defects counted. A: 5 or less B:6~10 C:11~20 D:21~50 E:51 and above

[0308] [Table 1]

[0309] The resist patterns formed through the above-described EUV exposure were evaluated, and as a result, the radiation-sensitive resin compositions of the examples were found to have good sensitivity, CDU performance, and development residue. [Industrial Applicability]

[0310] The radiation-sensitive resin composition and the method for forming a resist pattern described above can form a resist pattern that has good sensitivity to exposure light and is excellent in CDU performance and suppression of development residues. Therefore, these compositions can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. A resin containing a structural unit represented by the following formula (1): one or more onium salts each containing an organic acid anion moiety and an onium cation moiety, each of which contains a structure represented by the following formula (bd1): Solvent and Contains The radiation-sensitive resin composition includes the onium salt, at least a part of which onium cation moieties contain an aromatic ring structure having a fluorine atom. 【Chemical 1】 (In the above formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Y １ is a divalent aliphatic hydrocarbon group, and X １ is an acid-dissociable group.) 【Chemistry 2】 (In the above formula (bd1), R x1 to R x4 each independently represent a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining two or more of these together. R y1 and R y2 each independently represent a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining with each other. 【Chemistry 3】 is a double bond or a single bond. R z1 to R z4 each independently represent a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining two or more of these, provided that at least one of R x1 to R x4 , R y1 to R y2 , and R z1 to R z4 has an acid anion structure.

2. The onium salt is a radiation-sensitive acid generator containing the organic acid anion moiety and the onium cation moiety; and an acid diffusion controller which contains the organic acid anion moiety and the onium cation moiety, and which generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation; At least one selected from the group consisting of 2. The radiation-sensitive resin composition according to claim 1, wherein at least one of the onium cation moiety in the radiation-sensitive acid generator and the onium cation moiety in the acid diffusion controller contains the aromatic ring structure having a fluorine atom.

3. X in the above formula (1) １ The radiation-sensitive resin composition according to claim 1 or 2, wherein: 【Chemistry 4】 (In the above formula (s1), Cy is an aliphatic cyclic group formed together with carbon atoms. Ra ０１ ~Ra ０３ each independently represents a hydrogen atom, a substituted or unsubstituted monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or an aliphatic cyclic structure formed by combining two or more of these, provided that the aliphatic cyclic structure does not form a crosslinked structure. In the above formula (s2), Cy has the same meaning as in formula (s1) above. Ra ０４ is a substituted or unsubstituted aromatic hydrocarbon group. In the above formula, * indicates a bond to the oxygen atom.

4. 4. The radiation-sensitive resin composition according to claim 1, wherein the resin further comprises a structural unit having a phenolic hydroxyl group.

5. 5. The radiation-sensitive resin composition according to claim 1, wherein the resin further comprises a structural unit containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.

6. The radiation-sensitive resin composition according to any one of claims 1 to 5, further comprising a high-fluorine content resin having a higher mass content of fluorine atoms than the resin.

7. a step of directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 6 onto a substrate to form a resist film; exposing the resist film to light; developing the exposed resist film with a developer; A pattern forming method comprising:

8. 8. The pattern forming method according to claim 7, wherein the exposure is carried out using extreme ultraviolet rays or electron beams.

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