Radiation-sensitive composition, pattern formation method, and radiation-sensitive acid generator

Abstract

The purpose of the present invention is to provide: a radiation-sensitive composition capable of forming a resist film that can exhibit sensitivity and CDU at satisfactory levels when next-generation technology is applied and can suppress development defects; and a pattern formation method. The purpose of the present invention is also to provide a radiation-sensitive acid generator that can be applied to said radiation-sensitive composition. The present invention relates to a radiation-sensitive composition containing: a polymer (A) containing a structural unit (I) having an acid-dissociable group; a radiation-sensitive acid generator (B) represented by formula (1); and a solvent (C). (In formula (1): A is an (n1+n2+n3+1)-valent aromatic ring; R1 is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group; when there are multiple R1s, the multiple R1s are the same or different from one another; n1 is an integer of 1-5; n2 is an integer of 1-5; n3 is an integer of 0-5; m2 is an integer of 1-3; L is a single bond or an (m2+1)-valent linking group; Rf1 and Rf2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1-20 carbon atoms; Rf3 and Rf4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1-20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1-20 carbon atoms; when there are multiple Rf3s and multiple Rf4s, the multiple Rf3s and the multiple Rf4s may each be the same or different from one another; m1 is an integer of 0-10; and M+ is a monovalent onium cation.

Description

Radiation-sensitive composition, pattern forming method, and radiation-sensitive acid generator

[0001] The present invention relates to a radiation-sensitive composition, a pattern forming method, and a radiation-sensitive acid generator.

[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 promoted by using short-wavelength radiation such as an ArF excimer laser or by combining this radiation with a liquid immersion lithography method. As a next-generation technology, the use of even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is being attempted, and resist materials containing acid-generating compounds with structures that enhance the absorption efficiency of such radiation are also being investigated (Patent No. 4701231).

[0004] Patent No. 4701231

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

[0006] An object of the present invention is to provide a radiation-sensitive composition and a pattern forming method that are capable of forming a resist film that exhibits sufficient sensitivity and CDU and suppresses development defects when next-generation technologies are applied. Another object of the present invention is to provide a radiation-sensitive acid generator that can be used in the radiation-sensitive composition.

[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 relates to a radiation-sensitive composition comprising: a polymer (A) including a structural unit (I) having an acid-dissociable group; a radiation-sensitive acid generator (B) represented by the following formula (1); and a solvent (C): (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). R １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ If there are multiple R １ are the same or different. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a (m2+1)-valent linking group. Rf １ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When there are a plurality of Rf ３ and Rf ４ are the same or different. m1 is an integer of 0 to 10. M ＋ is a monovalent onium cation.

[0009] This radiation-sensitive composition allows the construction of a resist film that satisfies the sensitivity and CDU requirements and suppresses the occurrence of development defects. While the reason for this is unclear, it is presumed to be as follows: Because the anion of the radiation-sensitive acid generator (B) contains an iodine group, acid diffusion can be controlled by the molecular weight of the iodine atom. Furthermore, because the anion of the radiation-sensitive acid generator (B) contains an iodine group, the amount of secondary electrons generated increases, thereby increasing the sensitivity of the radiation-sensitive composition. These effects can improve the sensitivity and CDU. Furthermore, when an iodine group is introduced to improve sensitivity, the hydrophobicity of the iodine group reduces developer solubility. However, since the radiation-sensitive acid generator (B) contains a carboxyl group in addition to the iodine group, its affinity with an alkaline developer is increased. As a result, the occurrence of development defects is suppressed. It is presumed that these combined effects enable the resist performance and development defect suppression described above to be exhibited.

[0010] In another embodiment, the present invention relates to a pattern forming method, comprising the steps of: applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film; exposing the resist film; and developing the exposed resist film with a developer.

[0011] The pattern formation method uses the radiation-sensitive composition described above, which is capable of forming a resist film that has excellent sensitivity and CDU and is capable of suppressing the occurrence of development defects, and therefore can efficiently form a high-quality resist pattern.

[0012] In another embodiment, the present invention relates to a radiation-sensitive acid generator represented by the following formula (1): (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). R １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ If there are multiple R １ are the same or different. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a (m2+1)-valent linking group. Rf１ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When there are a plurality of Rf ３ and Rf ４ are the same or different. m1 is an integer of 0 to 10. M ＋ is a monovalent onium cation.

[0013] By using a radiation-sensitive composition containing the radiation-sensitive acid generator, it is possible to form a resist film that has excellent sensitivity and CDU and in which the occurrence of development defects is suppressed.

[0014] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. Combinations of preferred embodiments are also preferred.

[0015] <Radiation-Sensitive Composition> The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") comprises a polymer (A) containing a structural unit (I) having an acid-dissociable group, a radiation-sensitive acid generator (B) having a specific structure, and a solvent (C). The composition may contain other optional components as long as the effects of the present invention are not impaired. By including the radiation-sensitive acid generator (B) having a specific structure in the radiation-sensitive composition, a resist film obtained from the radiation-sensitive composition can exhibit higher levels of sensitivity, CDU, and suppression of development defects.

[0016] <Polymer (A)> The polymer (A) is an assembly of polymers containing a structural unit (I) having an acid-dissociable group (hereinafter, this assembly will also be referred to as a "base polymer"). The polymer (A) may contain a structural unit other than the structural unit (I).

[0017] The polymer (A) may contain an iodine group. Although the manner in which the iodine group is contained is not particularly limited, it is preferably contained in the form of an iodine group-containing aromatic ring structure. The iodine group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms in the aromatic ring are substituted with iodine groups. By containing an iodine group, radiation absorption efficiency can be increased, and secondary electron generation efficiency can be improved, thereby improving sensitivity.

[0018] The aromatic ring in the iodo group-containing aromatic ring structure is not particularly limited as long as it is a ring structure having aromaticity.Examples of the aromatic ring include aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, phenalene ring, phenanthrene ring, pyrene ring, fluorene ring, perylene ring, and coronene ring, furan ring, pyrrole ring, thiophene ring, phosphole ring, pyrazole ring, oxazole ring, isoxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, carbazole ring, dibenzofuran ring, benzofuran ring, indole ring, and benzothiophene ring, and other heteroaromatic rings, or combinations thereof.Among these, benzene ring is preferred as the aromatic ring.

[0019] The number of iodo groups in the iodo group-containing aromatic ring structure is not particularly limited, but is preferably 1 to 4, more preferably 1, 2 or 3, and even more preferably 1 or 2.

[0020] (Structural Unit (I)) The structural unit (I) is a structural unit having an acid-dissociable group. However, in this specification, a monomer corresponding to both the structural unit (I) and the structural unit (II) described later is included in the structural unit (I). The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and that dissociates under the action of an acid. The acid generated from the radiation-sensitive acid generator (B) described later upon exposure dissociates the acid-dissociable group in the structural unit (I) to generate a carboxy group or the like. This creates a difference in solubility in a developer between the exposed and unexposed areas of the resist film, making it possible to form a pattern.

[0021] The structural unit (I) 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 composition, a structural unit represented by the following formula (A1) (hereinafter, also referred to as "structural unit (I-1)") is preferred:

[0022]

[0023] In the above formula (A1), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Ａ２ and R Ａ３ are each independently a monovalent chain hydrocarbon group having 1 to 20 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. m11 and m12 are each independently 0 or 1. However, when m11 is 1, m12 is 1. When m11 is 0, L Ａ１ represents a single bond or a divalent linking group; when m11 is 1, L Ａ１ represents a divalent linking group. In the above hydrocarbon groups, chain hydrocarbon groups and alicyclic hydrocarbon groups, some or all of the hydrogen atoms on the carbon atoms may be substituted with substituents such as halogen atoms.

[0024] L Ａ１ Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, an arenediyl group, and groups having —CO—, —CS—, —O—, —S—, —SO— between the carbon-carbon bonds of these groups. ２Examples include -, -NR'-, or a group containing a combination of two or more of these, or a group combining these. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with, for example, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group; an alkoxy group; an alkoxycarbonyl group; an alkoxycarbonyloxy group; an acyl group; an acyloxy group, or a group in which the hydrogen atoms of these groups have been substituted with halogen atoms.

[0025] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, or a 2,2-propanediyl group.

[0026] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0027] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0028] Examples of the arenediyl group include a benzenediyl group, a toluenediyl group, a naphthalenediyl group, etc. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0029] The above R Ａ１ 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 20 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.

[0030] R Ａ１ ~R Ａ３Examples of the monovalent linear hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms. Examples of the monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, an n-pentyl group, an isopentyl group, and a neopentyl group. Examples of the monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms include alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0031] The above R Ａ１ ~R Ａ３ Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of monocyclic saturated hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of polycyclic saturated hydrocarbon groups include bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl. Examples of monocyclic unsaturated hydrocarbon groups include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl. Examples of polycyclic unsaturated hydrocarbon groups include polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms that constitute the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0032] The above R Ａ１ Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0033] The above R Ａ１ is preferably a hydrogen atom, a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, a monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0034] R Ａ２ and R Ａ３ As the divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded, a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0035] R Ａ２ and R Ａ３ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or R Ａ２ and R Ａ３ are combined together together with the carbon atoms to which they are bonded, a divalent alicyclic group having 3 to 20 carbon atoms is preferred, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic group having 5 to 10 carbon atoms is more preferred, and a methyl group, an ethyl group, a cyclopentanediyl group, or a cyclohexanediyl group is even more preferred.

[0036] When m11 is 0, L Ａ１ is preferably a single bond or an arenediyl group. Ａ１ is preferably an alkanediyl group.

[0037] Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-14) (hereinafter also referred to as "structural units (I-1) to (I-14)").

[0038]

[0039]

[0040] In the above formulas (1-1) to (1-14), R α , R Ａ１ ~R Ａ３has the same meaning as formula (A1) above. X is a hydroxy group, a halogen atom, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an alkoxy group. i and j are each independently an integer of 1 to 4. k and l are 0 or 1. a1 is an integer of 0 to 3. When a1 is 2 or more, multiple Xs are the same or different. a4 is an integer of 1 to 3.

[0041] i, j, k, and l are preferably 1 or 2. a4 is preferably 1. R Ａ１ R is preferably a methyl group, an ethyl group, a t-butyl group, a phenyl group, or an iodophenyl group. Ａ２ and R Ａ３ As X, a methyl group, an ethyl group, or an isopropyl group is preferable. As X, a hydroxy group, an iodine atom, or an alkyl group is preferable. By employing an iodine atom as X, an iodine group can be suitably introduced into the structural unit (I).

[0042] Furthermore, the polymer (A) may contain, as the structural unit (I), structural units represented by the following formulae (1f) to (2f).

[0043]

[0044] In the above formulas (1f) to (2f), R αｆ R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆ are each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. h1 is an integer of 1 to 4.

[0045] The above R βｆ is preferably a hydrogen atom, a methyl group or an ethyl group. h1 is preferably 1 or 2.

[0046] Specific examples of the structural unit (I) include, but are not limited to, those shown below.

[0047] (In the formula, R α has the same meaning as formula (A1) above.

[0048] (In the formula, R α has the same meaning as formula (A1) above.

[0049] The base polymer may contain one type of structural unit (I) or a combination of two or more types.

[0050] The lower limit of the content of the structural unit (I) (the total content when multiple types are contained) relative to all structural units constituting the base polymer is preferably 20 mol%, more preferably 30 mol%, and even more preferably 40 mol%. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive composition can be further improved.

[0051] (Structural Unit (II)) The polymer (A) preferably further contains a structural unit (II) having a phenolic hydroxyl group. Examples of monomers that provide the structural unit (II) include, but are not limited to, those shown below. In the following formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0052]

[0053]

[0054] When the polymer (A) contains the structural unit (II), the lower limit of the content of the structural unit (II) (the total content when multiple types are contained) relative to all structural units constituting the base polymer (A) is preferably 15 mol%, more preferably 20 mol%, even more preferably 25 mol%, and particularly preferably 30 mol%. The upper limit of this content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of the structural unit (II) within the above range, the pattern formability of the radiation-sensitive composition can be further improved.

[0055] (Structural Unit (III)) The polymer (A) may further contain another structural unit (III) containing a polar group such as an alcoholic hydroxyl group, a carboxyl group, a lactone ring, a sultone ring, an ether group, an ester group, a carbonyl group, or a cyano group. Monomers that provide the other structural unit (III) include, but are not limited to, those shown below. In the following formula, R Ａ is the same as above.

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] When the polymer (A) contains the structural unit (III), the lower limit of the content of the structural unit (III) (the total content when multiple types are contained) is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol% relative to all structural units constituting the base polymer (A). The upper limit of the content is preferably 40 mol%, more preferably 30 mol%. By setting the content of the structural unit (III) within the above range, pattern adhesion can be further improved.

[0067] (Structural Unit (IV)) The polymer (A) may further contain a structural unit (IV) having an organic acid anion and an onium cation. When the polymer (A) contains the structural unit (IV), the lower limit of the content of the structural unit (IV) (the total content when multiple types are contained) is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol%, based on all structural units constituting the base polymer (A). The upper limit of the content is preferably 30 mol%, more preferably 20 mol%. By setting the content of the structural unit (IV) within the above range, sensitivity can be further improved.

[0068] (Method for synthesizing polymer (A)) The polymer (A) can be synthesized, for example, by adding a radical polymerization initiator to a monomer that provides the structural unit described above in an organic solvent and heating the mixture to polymerize it. Known polymerization initiators can be used for the polymerization.

[0069] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy groups may be deprotected by the above-mentioned alkaline hydrolysis to form hydroxystyrene units or hydroxyvinylnaphthalene units. Alternatively, polymerization may be carried out without protecting the hydroxyl groups.

[0070] The polymer (A) has a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) using THF as a solvent of preferably 2,000, more preferably 4,000. The upper limit of Mw is preferably 30,000, more preferably 15,000. When Mw is within the above range, the resist material exhibits good pattern formability and heat resistance.

[0071] Furthermore, if the polymer (A) has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the shape of the pattern may be deteriorated. As the pattern rule becomes finer, the effects of Mw and molecular weight distribution tend to become greater. Therefore, in order to obtain a resist material that is suitable for use with fine pattern dimensions, it is preferable that the molecular weight distribution of the polymer (A) is narrow, i.e., 1.0 to 2.0, and particularly 1.0 to 1.8.

[0072] The polymer (A) may contain two or more polymers having different composition ratios, Mws, and molecular weight distributions.

[0073] The lower limit of the content of the polymer (A) in the radiation-sensitive composition is preferably 40% by mass, more preferably 50% by mass, based on the amount of the components other than the solvent (C) contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99% by mass, more preferably 95% by mass.

[0074] <Radiation-Sensitive Acid Generator (B)> The composition according to this embodiment contains a radiation-sensitive acid generator (B) represented by the following formula (1). (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). R １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ If there are multiple R １ are the same or different. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a (m2+1)-valent linking group. Rf １ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When there are a plurality of Rf ３ and Rf４ are the same or different. m1 is an integer of 0 to 10. M ＋ is a monovalent onium cation.

[0075] The aromatic ring represented by A can be an aromatic hydrocarbon ring, a heteroaromatic ring, or a combination thereof, as exemplified above for the aromatic ring in the iodo group-containing aromatic ring structure. Among these, the aromatic ring is preferably a benzene ring, a naphthalene ring, or a benzothiophene ring, more preferably a benzene ring or a naphthalene ring, and further preferably a benzene ring from the viewpoint of development defects.

[0076] As the (n1+n2+n3+1)-valent aromatic ring, a group obtained by removing (n1+n2+n3+1) hydrogen atoms from the above aromatic ring can be suitably used.

[0077] The above R １ Examples of the monovalent organic group represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the carbon chain terminal, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing group, and a combination thereof.

[0078] The monovalent hydrocarbon group having 1 to 20 carbon atoms in the organic group is R Ａ１ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0079] Examples of heteroatoms constituting the monovalent heteroatom-containing group and divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0080] Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0081] Examples of the divalent heteroatom-containing group include -CO-, -C(=O)O-, -CS-, -NH-, -O-, -S-, -SO-, and -SO ２ -, or a combination thereof.

[0082] The above R １ The monovalent organic group represented by the formula (I) is preferably a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and having a divalent heteroatom-containing group at the carbon chain terminal thereof, more preferably an alkyl group having 1 to 10 carbon atoms, or an alkylcarbonylamino group having 2 to 10 carbon atoms.

[0083] The (m2+1)-valent linking group represented by L above, when m2 is 1, is, for example, L Ａ１ When m2 is 2 or 3, L Ａ１ or a group in which (m2-1) hydrogen atoms have been removed from a divalent linking group represented by Ａ１ and a group obtained by removing (m2-1) hydrogen atoms from a divalent linking group represented by the following formula:

[0084] The (m2+1)-valent linking group represented by L preferably contains -O-, -CO-, a cyclic structure, or a combination thereof.

[0085] The cyclic structure may be a monocycle, a polycycle, or a combination thereof. The cyclic structure may be an alicyclic structure, an aromatic ring structure, a heterocyclic structure, or a combination thereof. In the case of a combination, the ring structures may be bonded to each other in a chain structure, or two or more ring structures may form a fused ring structure or a bridged ring structure. A divalent heteroatom-containing group may be present between carbon atoms forming the backbone of the cyclic structure or chain structure, and some or all of the hydrogen atoms on the carbon atoms of the cyclic structure or chain structure may be substituted with other substituents.

[0086] The alicyclic structure may be R Ａ１ ~RＡ３ A structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably employed.

[0087] Examples of the aromatic ring structure and heterocyclic structure include the aromatic hydrocarbon ring and heterocyclic structure exemplified as the aromatic ring in the iodo group-containing aromatic ring structure.

[0088] The heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal structure, or a combination thereof.

[0089] The chain structure may be R Ａ１ ~R Ａ３ A monovalent chain hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0090] Specifically, the linking group is preferably a group having at least one structure selected from the structures represented by the following formulas (L-1) and (L-2).

[0091] (In formula (L-1), R ４１ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. ４２ is a single bond or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms. ４３ is a single bond or a divalent organic group having 1 to 10 carbon atoms. Q is a cyclic acetal structure that forms a single ring or a condensed ring together with two oxygen atoms and the carbon atoms to which they are bonded. * is a bond that bonds to A in the above formula (1), and ** is Rf in the above formula (1). ３ and Rf ４ (When m1 is 0, Rf １ and Rf ２ is the bond that bonds to the carbon atom to which (In formula (L-2), R ４２ , R ４３ , Q has the same meaning as in formula (L-1) above. ４４ is a single bond or a divalent organic group. * is a bond bonded to A in the above formula (1), and ** is Rf in the above formula (1). ３ and Rf４ (When m1 is 0, Rf １ and Rf ２ is the bond that bonds to the carbon atom to which

[0092] R in the above formula (L-1) ４１ is the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R Ａ１ A monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula (I) can be suitably used.

[0093] R in the above formulas (L-1) and (L-2) ４２ , R ４３ The divalent organic group having 1 to 10 carbon atoms represented by the above R １ A group in which one hydrogen atom has been removed from a monovalent organic group represented by the following formula can be suitably used.

[0094] The above Rf １ , Rf ２ , Rf ３ , Rf ４ Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0095] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms include fluorinated alkyl groups such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a heptafluoro-n-propyl group, a heptafluoro-i-propyl group, a nonafluoro-n-butyl group, a nonafluoro-i-butyl group, a nonafluoro-t-butyl group, a 2,2,3,3,4,4,5,5-octafluoro-n-pentyl group, a tridecafluoro-n-hexyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group; fluorinated alkenyl groups such as a trifluoroethenyl group and a pentafluoropropenyl group; and fluorinated alkynyl groups such as a fluoroethynyl group and a trifluoropropynyl group.

[0096] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as a fluorocyclopentyl group, a difluorocyclopentyl group, a nonafluorocyclopentyl group, a fluorocyclohexyl group, a difluorocyclohexyl group, an undecafluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, and a fluorotricyclodecyl group; and fluorinated cycloalkenyl groups such as a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0097] The fluorinated hydrocarbon group is preferably a monovalent fluorinated chain hydrocarbon group having 1 to 8 carbon atoms, more preferably a monovalent fluorinated straight chain hydrocarbon group having 1 to 5 carbon atoms.

[0098] The above Rf ３ and Rf ４ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (A1) is Ａ１ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0099] The above Rf １ and Rf ２ As the Rf, a fluorine atom is preferred. ３ and Rf ４ is preferably a fluorine atom or a hydrogen atom.

[0100] The n1 is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, and from the viewpoint of sensitivity, even more preferably 2. The n2 is an integer of 1 to 5, preferably an integer of 1 to 3, and more preferably 1 or 2. The n3 is an integer of 0 to 5, preferably an integer of 0 to 2, and more preferably 0 or 1. The m2 is an integer of 1 to 3, preferably 1 or 2, and from the viewpoint of solubility in an alkaline developer, preferably 1.

[0101] The above m1 is an integer of 0 to 10, and preferably an integer of 0 to 3.

[0102] Specific examples of the anion of the radiation-sensitive acid generator (B) represented by the above formula (1) include, but are not limited to, the following structures:

[0103]

[0104]

[0105]

[0106]

[0107] The above M ＋ Examples of the monovalent onium cation represented by the formula (I) include a radiation-decomposable onium cation. Examples of the radiation-sensitive onium cation include a sulfonium cation, a tetrahydrothiophenium cation, an iodonium cation, etc. Among these, a sulfonium cation or an iodonium cation is preferred, and a sulfonium cation is more preferred.

[0108] From the viewpoint of sensitivity, the onium cation preferably has an iodo group, and more preferably contains the iodo group-containing aromatic ring structure.

[0109] The onium cation is preferably a fluoro-group-containing onium cation having a fluoro group. The fluoro-group-containing onium cation preferably has a fluoro-group-containing aromatic ring structure. The fluoro-group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms in the aromatic ring are substituted with fluoro groups or trifluoromethyl groups. The aromatic ring in the fluoro-group-containing aromatic ring structure can be suitably the same as the aromatic ring in the iodine-group-containing aromatic ring structure. This increases the radiation absorption efficiency, thereby improving sensitivity.

[0110] The sulfonium cation is preferably represented by the following formula (Q-1).

[0111]

[0112] In the above formula (Q-1), Ra1 to Ra3 each independently represent a substituent. n11 represents an integer of 0 to 5, and when n11 is 2 or greater, multiple Ra1s may be the same or different. n12 represents an integer of 0 to 5, and when n12 is 2 or greater, multiple Ra2s may be the same or different. n13 represents an integer of 0 to 5, and when n13 is 2 or greater, multiple Ra3s may be the same or different. Ra1 and Ra2 may be bonded to each other to form a ring. When n11 is 2 or greater, multiple Ra1s may be bonded to each other to form a ring. When n12 is 2 or greater, multiple Ra2s may be bonded to each other to form a ring.

[0113] The substituents represented by Ra1, Ra2, and Ra3 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.

[0114] The alkyl groups of Ra1, Ra2, and Ra3 may be linear or branched alkyl groups. Ａ１ ~R Ａ３ Preferably, a monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms in the following formula can be used. Among these, a methyl group, an ethyl group, an n-butyl group, and a t-butyl group are particularly preferred.

[0115] The cycloalkyl groups of Ra1, Ra2, and Ra3 include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Among these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.

[0116] Examples of the alkyl group moiety of the alkoxy group of Ra1, Ra2, and Ra3 include those previously listed as the alkyl group of Ra1, Ra2, and Ra3. As the alkoxy group, a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group are particularly preferred.

[0117] Examples of the cycloalkyl group moiety of the cycloalkyloxy group of Ra1, Ra2, and Ra3 include those previously listed as the cycloalkyl groups of Ra1, Ra2, and Ra3. As this cycloalkyloxy group, a cyclopentyloxy group and a cyclohexyloxy group are particularly preferred.

[0118] Examples of the alkoxy group moiety of the alkoxycarbonyl group of Ra1, Ra2, and Ra3 include those previously listed as the alkoxy groups of Ra1, Ra2, and Ra3. As the alkoxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl group, and an n-butoxycarbonyl group are particularly preferred.

[0119] Examples of the alkyl group moiety of the alkylsulfonyl group of Ra1, Ra2, and Ra3 include those previously listed as the alkyl groups of Ra1, Ra2, and Ra3. Furthermore, examples of the cycloalkyl group moiety of the cycloalkylsulfonyl group of Ra1, Ra2, and Ra3 include those previously listed as the cycloalkyl groups of Ra1, Ra2, and Ra3. Particularly preferred of these alkylsulfonyl groups or cycloalkylsulfonyl groups are methanesulfonyl, ethanesulfonyl, n-propanesulfonyl, n-butanesulfonyl, cyclopentanesulfonyl, and cyclohexanesulfonyl.

[0120] Each of the groups Ra1, Ra2, and Ra3 may further have a substituent, such as a halogen 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.

[0121] Examples of the halogen atom for Ra1, Ra2, and Ra3 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom and an iodine atom being preferred.

[0122] The halogenated hydrocarbon group of Ra1, Ra2, and Ra3 is preferably a halogenated alkyl group. Examples of the alkyl group and halogen atom constituting the halogenated alkyl group are the same as those described above. Among them, a fluorinated alkyl group is preferred, and CF ３ is more preferred.

[0123] As described above, Ra1 and Ra2 may be bonded to each other to form a ring (i.e., a heterocycle containing a sulfur atom). In this case, it is preferable that Ra1 and Ra2 are bonded to each other to form a single bond or a divalent linking group. Examples of the divalent linking group include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, and -SO ２ -, an alkylene group, a cycloalkylene group, an alkenylene group, or a combination of two or more of these, and those having a total carbon number of 20 or less are preferred. When Ra1 and Ra2 are bonded to each other to form a ring, Ra1 and Ra2 are bonded to each other to form -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO ２ It is preferable that n11 is - or a single bond. Among these, it is more preferable to form -O-, -S- or a single bond, and it is particularly preferable to form a single bond. Furthermore, when n11 is 2 or more, multiple Ra1s may be linked to each other to form a ring, and when n12 is 2 or more, multiple Ra2s may be linked to each other to form a ring. Such an example includes an embodiment in which two Ra1s are linked to each other to form a naphthalene ring together with the benzene ring to which they are bonded.

[0124] Ra3 is preferably a fluorine atom or a group having one or more fluorine atoms. 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, and CF３ , C ２ F ５ , C ３ F ７ , C ４ F ９ , C ５ F １１ , C ６ F １３ , C ７ F １５ , C ８ F １７ , C.H. ２ CF ３ , C.H. ２ CH ２ CF ３ , C.H. ２ C ２ F ５ , C.H. ２ CH ２ C ２ F ５ , C.H. ２ C ３ F ７ , C.H. ２ CH ２ C ３ F ７ , C.H. ２ C ４ F ９ and CH ２ CH ２ C ４ F ９ More preferred examples include CF ３ are particularly preferred.

[0125] Ra3 is a fluorine atom or CF ３ is preferably, and a fluorine atom is more preferably.

[0126] n11 and n12 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2.

[0127] n13 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0128] (n11+n12+n13) 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.

[0129] Specific examples of such onium cations represented by the above formula (Q-1) include the following:

[0130] (In the formula, tBu represents a t-butyl group, and Me represents a methyl group.)

[0131]

[0132] (In the formula, Me represents a methyl group.)

[0133]

[0134]

[0135] (In the formula, Me represents a methyl group.)

[0136]

[0137] (In the formula, Me represents a methyl group.)

[0138] Specific examples of the iodonium cation include the following:

[0139] Examples of the radiation-sensitive acid generator (B) represented by the above formula (1) include the following structures.

[0140]

[0141]

[0142]

[0143]

[0144] A known radiation-sensitive acid generator can also be used in combination as long as it does not impair the effects of the present invention.

[0145] The radiation-sensitive acid generator (B) may be used alone or in combination of two or more kinds. The lower limit of the content of the radiation-sensitive acid generator (B) (total amount when multiple types are used) is preferably 5 parts by mass, more preferably 10 parts by mass, even more preferably 25 parts by mass, even more preferably 40 parts by mass, and particularly preferably 55 parts by mass, per 100 parts by mass of the polymer (A). The upper limit of the content is preferably 90 parts by mass, more preferably 85 parts by mass, and even more preferably 80 parts by mass, per 100 parts by mass of the polymer (A). This allows excellent sensitivity and CDU to be exhibited during resist pattern formation.

[0146] <Acid Diffusion Controller (D)> From the viewpoint of CDU, the composition according to this embodiment preferably contains an acid diffusion controller (D). The acid diffusion controller (D) contains an organic acid anion and an onium cation, and generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator (B) upon irradiation with radiation. The acid diffusion controller (D) containing an organic acid anion and an onium cation is preferably represented by any of the following formulas (8-1) to (8-4).

[0147]

[0148] In the above formula (8-1) and formula (8-2), J ＋ is a sulfonium cation, and U ＋ is an iodonium cation. E in the above formula (8-1) and formula (8-2) － and Q － are each independently R ８ SO ３ － , R ８ COO － , and (R ８ SO ２ ) N － Preferably, R is at least one selected from the group consisting of ８ COO －Further, examples of the compound include a compound represented by the above formula (8-3) containing a sulfonium cation and an anion in the same molecule, and a compound represented by the above formula (8-4) containing an iodonium cation and an anion in the same molecule. In the above formulas (8-3) and (8-4), J' ＋ is a monovalent group having a sulfonium cation structure, and U' ＋ is a monovalent group having an iodonium cation structure. － and Q' － are each independently -R ８１ SO ３ － , -R ８１ COO － , and -R ８１ SO ２ N － SO ２ R ８ Preferably, the group is at least one selected from the group consisting of -R ８１ COO － It is more preferable that the above R ８ is a monovalent organic group, and the R ８１ is a single bond or a divalent organic group.

[0149] From the viewpoint of sensitivity, the organic acid anion may have an iodine group, and more preferably contains the iodine group-containing aromatic ring structure.

[0150] Examples of the organic acid anion include anions represented by the following formula:

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158] J ＋ As the sulfonium cation, the sulfonium cation represented by the above formula (Q-1) can be suitably used.

[0159] U ＋ As the iodonium cation, those exemplified above for the radiation-sensitive acid generator (B) can be suitably used.

[0160] The acid diffusion controller (D) can be synthesized by a known method, particularly a salt exchange reaction. Known acid diffusion controllers other than those mentioned above can also be used as long as they do not impair the effects of the present invention.

[0161] These acid diffusion controllers (D) may be used alone or in combination of two or more. The lower limit of the content of the acid diffusion controller (D) (total amount when multiple types are used) is preferably 3 parts by mass, more preferably 5 parts by mass, and even more preferably 7 parts by mass, per 100 parts by mass of the polymer (A). The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 20 parts by mass. This allows excellent sensitivity and CDU to be exhibited during resist pattern formation.

[0162] <Other Polymers> The radiation-sensitive composition of the present embodiment may contain, as another polymer, a polymer having a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine-content polymer (E)"). When the radiation-sensitive composition contains the high-fluorine-content polymer (E), the high-fluorine-content polymer can be unevenly distributed in the surface layer of the resist film relative to the base polymer, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to desired states.

[0163] The high-fluorine-containing polymer (E) preferably has a structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit (V)"): In addition, for example, the high-fluorine-containing polymer (E) may have at least one of the structural units (I) to (III) in the base polymer, if necessary.

[0164] In the above formula (6), R ７３ is a hydrogen atom, a methyl group, or a trifluoromethyl group.Ｌ represents a single bond, an oxygen atom, a sulfur atom, -COO-, or -SO ２ ONH-, -CONH- or -OCONH-. ７４ 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.

[0165] The above R ７３ As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0166] Above G Ｌ As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and —COO— are preferred, and —COO— is more preferred.

[0167] The above R ７４ Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0168] The above R ７４ Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0169] The above R ７４ As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 1-(trifluoromethyl)-2,2,2-trifluoroethyl group or a 4,4,4-trifluoro-3-hydroxy-3-trifluoromethylbutyl group is even more preferable.

[0170] When the high-fluorine content polymer (E) has the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%, based on all structural units constituting the high-fluorine content polymer (E). The upper limit of the content is preferably 100 mol%, more preferably 95 mol%, and even more preferably 90 mol%. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine content polymer can be more appropriately adjusted, thereby further promoting uneven distribution of fluorine atoms in the surface layer of the resist film.

[0171] The lower limit of Mw of the high fluorine content polymer (E) 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 20,000, and particularly preferably 15,000.

[0172] The Mw / Mn of the high fluorine content polymer (E) is usually at least 1, and more preferably at least 1.1. The Mw / Mn is usually at most 5, preferably at most 3, more preferably at most 2.5, and even more preferably at most 2.2.

[0173] The lower limit of the content of the high fluorine-containing polymer (E) is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 1.5 parts by mass, relative to 100 parts by mass of the polymer (A). The upper limit of the content is preferably 10 parts by mass, more preferably 8 parts by mass, and even more preferably 5 parts by mass. By setting the content of the high fluorine-containing polymer (E) within the above range, the high fluorine-containing polymer (E) can be more effectively localized to the surface layer of the resist film, thereby suppressing elution from the upper part of the pattern during development and improving the rectangularity of the pattern. The radiation-sensitive composition may contain one or more high fluorine-containing polymers (E).

[0174] (Method for synthesizing high fluorine content polymer (E)) The high fluorine content polymer (E) can be synthesized by the same method as the above-mentioned method for synthesizing the base polymer.

[0175] <Solvent (C)> The radiation-sensitive composition according to this embodiment contains a solvent (C). The solvent (C) is not particularly limited as long as it is a solvent that can dissolve or disperse the polymer (A) and optional additives and the like.

[0176] Examples of the solvent (C) include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0177] Examples of alcohol-based solvents include monoalcohol-based 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, diacetone alcohol, and methyl 2-hydroxyisobutyrate; polyhydric alcohol-based 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; and polyhydric alcohol partially etherified solvents in which some of the hydroxy groups in the above-mentioned polyhydric alcohol-based solvents have been etherified.

[0178] In the present embodiment, alcoholic acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, i-propyl 2-hydroxyisobutyrate, i-butyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcoholic solvents.

[0179] Examples of ether-based solvents include dialkyl ether-based solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether-based solvents such as diphenyl ether and anisole (methyl phenyl ether); and polyhydric alcohol ether-based solvents obtained by etherifying the hydroxy groups of the above-mentioned polyhydric alcohol-based solvents.

[0180] Examples of the ketone solvent include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0181] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0182] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate-based solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone-based solvents such as γ-butyrolactone and valerolactone; carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyvalent carboxylic acid diester-based solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0183] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0184] Among these, ester-based solvents, ketone-based solvents, alcohol-based solvents, and ether-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents, lactone-based solvents, alcohol acid ester-based solvents, polyhydric alcohol partial ether-based solvents, and monocarboxylic acid ester-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone, γ-butyrolactone, propylene glycol monomethyl ether, diacetone alcohol, ethyl lactate, and methyl 2-hydroxy-2-methylpropionate are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0185] <Other Optional Components> The radiation-sensitive composition may contain other optional components in addition to the components described above. 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.

[0186] <Method for Preparing Radiation-Sensitive Composition> The radiation-sensitive composition can be prepared, for example, by mixing the polymer (A), the radiation-sensitive acid generator (B), and the solvent (C), and, if necessary, other optional components, in a predetermined ratio. After mixing, the radiation-sensitive composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.4 μm. The solids concentration of the radiation-sensitive composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0187] <<Pattern Forming Method>> The pattern forming method of the present embodiment includes: a step (1) of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film to light (hereinafter also referred to as an "exposure step"); and a step (3) of developing the exposed resist film with a developer (hereinafter also referred to as a "development step").

[0188] According to the pattern forming method, since the radiation-sensitive composition capable of forming a resist film excellent in sensitivity, CDU, and suppression of development defects is used, a high-quality resist pattern can be formed.

[0189] [Resist Film Forming Step] In this step (step (1) above), a resist film is formed from the radiation-sensitive 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 JP-B-6-12452 and JP-A-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 160°C, preferably 80°C to 140°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0190] When the subsequent exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a polymer having the structural unit (II) as the base polymer in the composition.

[0191] [Exposure Step] In this step (the above step (2)), the resist film formed in the above step (1), the resist film formation step, is exposed by irradiating it with radiation through a photomask (or, in some cases, through an immersion medium such as water). Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. 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.

[0192] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the polymer 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 typically 50°C to 180°C, preferably 80°C to 150°C. The PEB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0193] [Development Step] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed with a developer. 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.

[0194] In the case of alkaline development, examples of the developer used in the development include an alkaline aqueous solution containing at least one alkaline compound dissolved therein, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0195] 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 an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive 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.

[0196] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of piling up a developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time to develop (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0197] <Radiation-Sensitive Acid Generator> The radiation-sensitive acid generator of the present embodiment is represented by the following formula (1). (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). R １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ If there are multiple R １ are the same or different. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a (m2+1)-valent linking group. Rf １ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When there are a plurality of Rf ３ and Rf ４ are the same or different. m1 is an integer of 0 to 10. M ＋ is a monovalent onium cation.

[0198] As the radiation-sensitive acid generator, the radiation-sensitive acid generator (B) in the radiation-sensitive composition can be suitably used.

[0199] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0200] [Measurement of Weight-Average Molecular Weight (Mw), Number-Average Molecular Weight (Mn), and Dispersity (Mw / Mn)] Measurement was performed by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (two "G2000HXL," one "G3000HXL," and one "G4000HXL") under the following conditions: Elution solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection amount: 100 μL Column temperature: 40° C. Detector: differential refractometer Standard material: monodisperse polystyrene

[0201] [ １ H-NMR analysis and １３ C-NMR Analysis] Measurement was carried out using a "JNM-Delta400" manufactured by JEOL Ltd.

[0202] <Synthesis of Polymer> The monomers used in the synthesis of each polymer in each Example and Comparative Example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is 100 mol %. Furthermore, the present invention is not limited to the following structural units.

[0203] The structures of the monomers used in the synthesis of the polymers in each example are shown below.

[0204] [Polymer Synthesis Method] [Polymer Synthesis Example 1] (Synthesis of Polymer (P-1)) Compound (M-1) and compound (M-5) as monomers were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) so that the molar ratio was 55 / 45. Next, azobisisobutyronitrile (AIBN, 4 mol%) was added as an initiator to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours, allowing the polymerization reaction to proceed for a total of 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, then filtered and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After completion of the reaction, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). The resin was coagulated by dropping the mixture into 500 parts by mass of water, and the resulting solid was filtered. The mixture was dried at 50°C for 12 hours to synthesize a white powdery polymer (P-1). The Mw of the resulting polymer (P-1) was 5100, and the Mw / Mn was 1.4. １３ As a result of C-NMR analysis, the content ratio of the structural unit derived from compound (M-1):the structural unit derived from compound (M-5) was 54:46 (mol %).

[0205] Polymer Synthesis Examples 2 to 14 (Synthesis of Polymers (P-2) to (P-14)) Polymers (P-2) to (P-14) were obtained in the same manner as in Polymer Synthesis Example 1, except that the types and amounts of monomers were changed as shown in Table 1. Table 1 shows the Mw and Mw / Mn of each obtained polymer, and the content of structural units derived from each monomer in each polymer.

[0206] [Polymer Synthesis Example 15] (Synthesis of Polymer (P-15)) (M-20), (M-7), and compound (M-21) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) so that the molar ratio was 40 / 50 / 10. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol % relative to the total amount of monomers to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, and then dried at 50°C for 12 hours to obtain a white powdery polymer (P-15). The Mw of the obtained polymer (P-15) was 6700, and the Mw / Mn was 1.7. １３ As a result of C-NMR analysis, the content ratio of the structural unit derived from compound (M-20): the structural unit derived from compound (M-7): the structural unit derived from compound (M-21) was 39:51:10 (mol %).

[0207]

[0208] [Synthesis of Highly Fluorine-Containing Polymers] [Polymer Synthesis Example 16] (Synthesis of Polymer (E-1)) Compounds (M-18) and (M-19) as monomers were dissolved in 2-butanone (200 parts by mass) so that the molar ratio was 90 / 10. AIBN (5 mol % based on the total monomers) was added thereto as an initiator to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel, and the mixture was purged with nitrogen for 30 minutes. The temperature inside the reaction vessel was brought to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition was designated as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This procedure was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of polymer (E-1) was obtained in good yield.

[0209] Polymer Synthesis Example 17 (Synthesis of Polymer (E-2)) Polymer (E-2) was obtained in the same manner as in Polymer Synthesis Example 16, except that the types and amounts of monomers were changed as shown in Table 2. Table 2 shows the Mw, Mw / Mn, and content of structural units derived from each monomer in each polymer obtained. In Table 2, "-" indicates that the corresponding component was not used.

[0210]

[0211] <Preparation of Radiation-Sensitive Composition> The radiation-sensitive acid generator, acid diffusion controller, and solvent that constitute the radiation-sensitive composition are described below.

[0212] [Radiation-sensitive acid generators] B-1 to B-16: compounds represented by the following formulas (B-1) to (B-16)

[0213] Synthesis examples (Examples) of the acid generators represented by the above formulas (B-1) to (B-16) are shown below. [Example 1-1] (Synthesis of Radiation-Sensitive Acid Generator (B-1))

[0214]

[0215] To Compound 1 (5.00 g, 1.0 eq.),３ (7.43 g, 3.0 eq.) and water (100 mL) were added. Then, I was added to water (145 mL). ２ An aqueous solution containing 13.81 g (2.2 eq.) of HCl and 12.31 g (3.0 eq.) of KI was added dropwise and stirred at room temperature for 8 hours. After the reaction was completed, 100 mL of 2N aqueous HCl was added to the solution to precipitate a powder, which was then filtered. The filtered cake was washed with water and hexane, suspended in 100 mL of dichloromethane, and stirred at room temperature. The mixture was filtered and dried in vacuo to obtain Compound 2. The resulting compound was used in the subsequent reaction.

[0216]

[0217] Compound 2 (5.00 g, 1.0 eq) was dissolved in THF (50 mL), and then K ２ CO ３ (2.53 g, 1.2 eq) was added, and the solution was cooled to 5°C. While still cooled to 5°C, a solution of compound 3 (3.13 g, 1.5 eq) in THF (50 mL) was added dropwise, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, the mixture was quenched with 100 mL of saturated aqueous ammonium chloride solution. Ethyl acetate was added for extraction, and the organic layer was separated. The organic layer was dried over sodium sulfate, the solvent was removed, and the mixture was purified using a column to obtain compound 4.

[0218]

[0219] Compound 4 (5.00 g, 1.0 eq.) was added to a reaction vessel and dissolved in THF (50 mL) and methanol (25 mL). Then, a solution of NaOH (1.30 g, 2.5 eq.) in water (12.5 mL) was added, and the mixture was stirred at 75 ° C. for 8 hours. After the reaction was completed, 100 mL of 2N HCl aq. was added to the solution to precipitate a powder, which was then filtered. The residue was washed with water and then dissolved in THF (200 mL). The solution was dried over sodium sulfate, the solvent was removed, and the mixture was dried under vacuum to obtain compound 5.

[0220]

[0221] Compound 5 (4.58 g, 1.05 eq.), compound 6 (8.33 g, 1.00 eq.), sulfuric acid (0.347 g, 0.3 eq.), and toluene (100 mL) were added to a reaction vessel and stirred for 5 hours while refluxing at the boiling point. After cooling, the solvent was removed, and the residue was dissolved in a mixed solvent of 150 mL of dichloromethane and 75 mL of acetonitrile. 100 mL of 2N aqueous HCl was added and washed, and then the organic layer was separated. The separated organic layer was washed twice with water (100 mL), dried over sodium sulfate, and the solvent was removed. Compound (B-1) was obtained by column purification of the crude product.

[0222] Examples 1-2 to 1-16 (Synthesis of Radiation-Sensitive Acid Generators (B-2) to (B-16)) Compounds represented by the above formulas (B-2) to (B-16) were synthesized in the same manner as in Example 1-1, except that the precursors and intermediates were appropriately changed.

[0223] [Acid diffusion controller] D-1 to D-4: Compounds represented by the following formulas (D-1) to (D-4)

[0224]

[0225] [Solvent] C-1: Propylene glycol monomethyl ether acetate C-2: Propylene glycol monomethyl ether C-3: Diacetone alcohol

[0226] [Preparation of Radiation-Sensitive Composition for Exposure to Extreme Ultraviolet (EUV)] [Example 1] 100 parts by mass of (P-1) as the polymer (A), 70 parts by mass of (B-1) as the radiation-sensitive acid generator (B), 10 parts by mass of (D-1) as the acid diffusion controller (D), 2.0 parts by mass of (E-1) as the high fluorine-content polymer (E), and 1,750 parts by mass of (C-1) and 6,950 parts by mass of (C-2) as the solvents (C) were mixed together, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-1).

[0227] [Examples 2 to 29 and Comparative Examples 1 and 2] Radiation-sensitive compositions (J-2) to (J-29) and (CJ-1) to (CJ-2) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 3 below were used.

[0228]

[0229] <Formation of Resist Pattern Using Radiation-Sensitive Composition for EUV Exposure> A composition for forming a bottom antireflective coating (Brewer Science's ARC66) was applied to a 12-inch silicon wafer 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 20 nm. The radiation-sensitive composition for EUV exposure prepared above was applied to this bottom antireflective coating using the spin coater, and baked 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. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Conventional s = 0.89). The resist film was subjected to PEB (post-exposure bake) for 60 seconds at 100° C. Then, it was developed using a 2.38 wt % aqueous TMAH solution at 23° C. for 30 seconds to form a positive 25 nm contact hole pattern.

[0230] <Evaluation> The sensitivity and CDU of the resist patterns formed using the above radiation-sensitive composition for EUV exposure were evaluated according to the methods described below. The results are shown in Table 4. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0231] [Sensitivity] In forming a resist pattern using the radiation-sensitive composition for EUV exposure, the exposure dose for forming a 25 nm contact hole pattern is defined as the optimum exposure dose Eop, and this optimum exposure dose is defined as the sensitivity (mJ / cm ２ The sensitivity was 35 mJ / cm ２ The following cases are considered "good" and 35 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0232] [CDU] A resist pattern was formed by adjusting the mask size so that a 25 nm contact hole pattern was formed by irradiating the Eop exposure dose calculated above. The formed resist pattern was observed from above using the scanning electron microscope. The hole diameter was measured at 16 points within a 500 nm range to determine the average value, and this average value was measured at a total of 500 points at any desired points. The 1 sigma value was calculated from the distribution of the measured values, and this was defined as CDU (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, and the better. A CDU of 2.0 nm or less can be evaluated as "good," and a CDU of more than 2.0 nm can be evaluated as "poor."

[0233] [Number of Development Defects] A resist film was exposed to an optimum exposure dose to form a 25 nm contact hole pattern, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Of the defects measured, defects with a diameter of 0.5 μm or less were judged to be originating from the resist film. After development, the number of defects judged to be originating from the resist film was judged as "A" (very good) if the number was less than 30, "B" (good) if the number was 30 to 50, and "C" (poor) if the number was more than 50.

[0234] The evaluation results of the sensitivity, CDU, and number of development defects are shown in Table 4 below.

[0235]

[0236] As is clear from the results in Table 4, the radiation-sensitive compositions of the examples all exhibited good performance in terms of sensitivity, CDU, and number of development defects.

[0237] The radiation-sensitive composition and method for forming a resist pattern of the present invention enable the formation of a resist pattern with excellent performance in terms of sensitivity, CDU, and number of development defects, and therefore can be suitably used in the fabrication processes of semiconductor devices, which are expected to become increasingly miniaturized in the future.

Claims

1. A radiation-sensitive composition comprising: a polymer (A) containing a structural unit (I) having an acid-dissociable group; a radiation-sensitive acid generator (B) represented by the following formula (1); and a solvent (C): (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ When there are multiple R １ are the same or different from each other. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a linking group having a valence of (m2+1). Rf １ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When a plurality of Rf are present, a plurality of Rf ３ and Rf ４ are the same or different. m1 is an integer from 0 to 10. ＋ is a monovalent onium cation.

2. The radiation-sensitive composition according to claim 1, wherein the aromatic ring is a benzene ring or a naphthalene ring.

3. The radiation-sensitive composition according to claim 1, wherein the linking group includes -O-, -CO-, a cyclic structure, or a combination thereof.

4. The radiation-sensitive composition according to claim 1, wherein the onium cation is a sulfonium cation.

5. The radiation-sensitive composition according to claim 1, wherein the onium cation is a fluoro-group-containing onium cation.

6. The radiation-sensitive composition according to claim 1, wherein the polymer (A) further contains a structural unit (II) having a phenolic hydroxyl group.

7. The radiation-sensitive composition according to claim 1, wherein m2 is 1.

8. The radiation-sensitive composition according to claim 1, wherein the content of the radiation-sensitive acid generator (B) is 30 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the polymer (A).

9. The radiation-sensitive composition according to claim 1, further comprising an acid diffusion controller (D) which generates an acid having a higher pKa than the acid generated from said radiation-sensitive acid generator (B) upon exposure to radiation.

10. A pattern forming method comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 9 directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.

11. The method for forming a pattern according to claim 10, wherein the exposure is carried out using extreme ultraviolet rays or electron beams.

12. A radiation-sensitive acid generator represented by the following formula (1): (In the above formula (1), A is an aromatic ring having a valence of (n1+n2+n3+1). １ R is a nitro group, a cyano group, a hydroxy group, an amino group, or a monovalent organic group. １ When there are multiple R １ are the same or different from each other. n1 is an integer of 1 to 5. n2 is an integer of 1 to 5. n3 is an integer of 0 to 5. m2 is an integer of 1 to 3. L is a single bond or a linking group having a valence of (m2+1). Rf １ and Rf ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. ３ and Rf ４ When a plurality of Rf are present, a plurality of Rf ３ and Rf ４ are the same or different. m1 is an integer from 0 to 10. ＋ is a monovalent onium cation.

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