Onium salt compound

Abstract

To provide an onium salt compound capable of exhibiting sensitivity, LWR performance, and CDU performance at a sufficient level.SOLUTION: An onium salt compound comprising a structure represented by the following formula (1-2): (In the formula, Rf1 and Rf2 are each F or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms; R1 is H, a monovalent hydrocarbon group having 1 to 20 carbon atoms, F, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms; R2 to R7 are each H or a monovalent hydrocarbon group having 1 to 20 carbon atoms; n1 is an integer of 0 to 4; n2 is an integer of 0 to 4; provided that n1+n2 is an integer of 2 to 8; n3 is an integer of 0 to 5; X1 and X2 are each O or S; and Z+ is a monovalent radiation-sensitive onium cation).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to onium salt compounds. [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 developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] The photolithography technology mentioned above is promoting pattern miniaturization by using short-wavelength radiation such as ArF excimer lasers, and also by using liquid immersion lithography, in which exposure is performed with the space between the lens of the exposure device and the resist film filled with a liquid medium. Lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered as a next-generation technology.

[0004] As efforts toward further technological advances continue, attempts are being made to improve the sensitivity, resolution, etc. of photoacid generators, which are the main components of resist compositions. For example, studies are being conducted on photoacid generators that can provide strong acidity by substituting fluorine for the proximal carbon of a sulfonic acid group (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-12684 Summary of the Invention [Problem to be solved by the invention]

[0006] In these efforts toward next-generation technologies, resist performance equivalent to or better than conventional performance is required in terms of sensitivity, LWR (Line Width Roughness) performance indicating the variation in line width of the resist pattern, CDU (Critical Dimension Uniformity), etc. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition and a pattern forming method that can exhibit sufficient levels of sensitivity, LWR performance, and CDU performance. [Means for solving the problem]

[0008] 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.

[0009] That is, in one embodiment, the present invention provides: an onium salt compound having a structure represented by the following formula (1); Solvent and The present invention relates to a radiation-sensitive resin composition comprising: [ka] (In the above formula (1), R f1 and R f2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n1 is an integer from 0 to 4. Rf1 and R f2 If there are multiple of each, multiple R f1 and R f2 are the same or different from each other. n2 is an integer from 0 to 4. 1 and R 2 If there are multiple of each, multiple R 1 and R 2 are the same or different from each other. Here, n1+n2 is an integer of 2 to 8. n3 is an integer from 0 to 5. 3 and R 4 If there are multiple of each, multiple R 3 and R 4 are the same or different from each other. X 1 and X 2 are each independently an oxygen atom or a sulfur atom. * indicates a bond to another structure. Z + is a monovalent radiation-sensitive onium cation.

[0010] The radiation-sensitive resin composition contains an onium salt compound (hereinafter also referred to as "compound (1)") having a structure represented by the above formula (1) as a radiation-sensitive acid generator, and therefore exhibits excellent sensitivity, LWR performance, and CDU performance during resist pattern formation. Without being bound by any theory, the reason for this is presumed to be as follows: The bond of an electron-withdrawing group to the carbon atom to which a sulfo group is bonded enables the generated acid to be strongly oxidized, and the introduction of an ester bond and two adjacent (thio)ether structures into the backbone portion allows the acid diffusion length and affinity with the resin to be adjusted to appropriate levels, resulting in a synergistic effect that allows the desired resist performance to be exhibited. The organic group refers to a group containing at least one carbon atom.

[0011] 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:

[0012] In this pattern formation method, the radiation-sensitive resin composition, which has excellent sensitivity, LWR performance, and CDU performance, is used, and therefore a high-quality resist pattern can be efficiently formed. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0014] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as the "composition") contains compound (1) and a solvent. It further preferably contains a resin, and optionally contains an acid diffusion controller. The composition may contain other optional components as long as they do not impair the effects of the present invention. By containing compound (1) as a radiation-sensitive acid generator, the radiation-sensitive resin composition can be endowed with high levels of sensitivity, LWR performance, and CDU performance.

[0015] (Compound (1)) Compound (1) contains a structure represented by the following formula (1) (hereinafter also referred to as the "specific partial structure"). The form of compound (1) is not particularly limited as long as it contains the specific partial structure. Examples include a resin form in which the other structure to which the specific partial structure is bonded is a resin (resin skeleton) and the specific partial structure is a part of the resin structure (hereinafter, a resin having the specific partial structure is also referred to as an "acid-generating resin"). Also, a compound form in which the other structure to which the specific partial structure is bonded is an arbitrary group and the specific partial structure is a part of a low-molecular-weight compound. When the composition contains compound (1) in the form of a resin (when compound (1) is an acid-generating resin), it may or may not contain a resin, which is a preferred component described below. As long as it contains the specific partial structure, the acid-generating resin is treated as compound (1). When compound (1) is in the form of a compound, the composition preferably contains a resin described below. Whether compound (1) is in the form of a resin or a compound, the composition may contain one or more specific partial structures. When compound (1) has two or more specific partial structures, the multiple specific partial structures may be the same or different. Compound (1) is preferably in the form of a compound.

[0016] [ka]

[0017] In the above formula (1), R f1 and R f2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n1 is an integer from 0 to 4. R f1 and R f2If there are multiple of each, multiple R f1 and R f2 are the same or different from each other. n2 is an integer from 0 to 4. 1 and R 2 If there are multiple of each, multiple R 1 and R 2 are the same or different from each other. Here, n1+n2 is an integer of 2 to 8. n3 is an integer from 0 to 5. 3 and R 4 If there are multiple of each, multiple R 3 and R 4 are the same or different from each other. X 1 and X 2 are each independently an oxygen atom or a sulfur atom. * indicates a bond to another structure. Z + is a monovalent radiation-sensitive onium cation.

[0018] R f1 and R f2 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.

[0019] 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; Examples include fluorinated alkynyl groups such as a fluoroethynyl group and a trifluoropropynyl group.

[0020] 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, a fluorotricyclodecyl group, and a fluorotetracyclodecyl group; Examples include fluorinated cycloalkenyl groups such as a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0021] The fluorinated hydrocarbon group is preferably the above-mentioned monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms. As the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms, a group having 1 to 10 carbon atoms among the above-mentioned monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms can be suitably used.

[0022] R f1 and R f2 is preferably a fluorine atom in terms of the degree of freedom of the structure around the sulfo group and the acidity of the generated acid.

[0023] R 1 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent 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.

[0024] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms includes a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0025] Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bonding chain containing one or more carbon atoms.

[0026] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include: Examples thereof include aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl groups; and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0027] R 1 As the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R f1 and R f2 The monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms exemplified in the above can be suitably used.

[0028] R 2 , R 3 , R 4 , R 5 , R 6 and R 7 As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 1 The monovalent hydrocarbon groups having 1 to 20 carbon atoms exemplified in the above can be suitably used.

[0029] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently preferably a hydrogen atom or a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms. 1and R 2 are preferably both hydrogen atoms.

[0030] Preferably, n1 and n2 are each independently an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2. It is particularly preferred that both n1 and n2 are 1.

[0031] n1+n2 is preferably an integer of 2 to 4, more preferably 2 or 3, and even more preferably 2.

[0032] n3 is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, even more preferably 0 or 1, and particularly preferably 0.

[0033] X 1 and X 2 and are preferably both oxygen atoms.

[0034] In the above formula (1), the above Z + Examples of the monovalent radiation-sensitive onium cation represented by the formula (X-1) include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, such as sulfonium cation, tetrahydrothiophenium cation, iodonium cation, phosphonium cation, diazonium cation, and pyridinium cation. Among these, sulfonium cation or iodonium cation is preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] In the above formula (X-1), R a1 , R a2 and R a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -SR T or a ring structure formed by combining two or more of these groups. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R a1 ~R a3 and R P , R Q and R TIf there are multiple R a1 ~R a3 and R P , R Q and R T may be the same or different.

[0042] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. n k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer between 0 and 7. R b1 If there are multiple, multiple R b1 may be the same or different, and multiple R b1 R may represent a ring structure formed by combining with each other. b2 L is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R b2 If there are multiple, multiple R b2 may be the same or different, and multiple R b2 may represent a ring structure formed by combining with each other, and q is an integer of 0 to 3. In the formula, S + The ring structure containing may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton.

[0043] In the above formula (X-3), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0044] In the above formula (X-4), R g1is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. n k2 When is 0, k10 is an integer between 0 and 4, and n k2 When is 1, k10 is an integer between 0 and 7. R g1 If there are multiple, multiple R g1 may be the same or different, and multiple R g1 R may represent a ring structure formed by combining with each other. g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 If there are multiple R g2 and R g3 may be the same or different.

[0045] In the above formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, or a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 If there are multiple R d1 and R d2 may be the same or different.

[0046] In the above formula (X-6), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0047] Specific examples of the radiation-sensitive onium cation include, but are not limited to, structures of the following formulas:

[0048] [ka]

[0049] [ka]

[0050] Compound (1) may have a structure in which any anion moiety containing a specific partial structure is combined with any radiation-sensitive onium cation.

[0051] When compound (1) is in the form of a compound, the compound is preferably an onium salt compound represented by the following formula (1-1) (hereinafter also referred to as "compound (1-1)") or an onium salt compound represented by the following formula (1-2) (hereinafter also referred to as "compound (1-2)"). [ka]

[0052] In the above formulas (1-1) and (1-2), R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R6 , R 7 , n1, n2, n3, X 1 , X 2 and Z + is synonymous with the above formula (1). R 8a and R 9a are each independently a monovalent organic group having 1 to 40 carbon atoms. R 8b and R 9b are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R 8b and R 9b represent a ring structure having 3 to 20 ring members formed by combining with each other and the carbon atoms to which they are attached. n4 is an integer from 1 to 4. 8b and R 9b If there are multiple of each, multiple R 8b and R 9b are the same or different.)

[0053] R 8a , R 9a , R 8b and R 9b The monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) is not particularly limited and may have a chain structure, a cyclic structure, or a combination thereof. Examples of the chain structure include chain hydrocarbon groups, whether saturated or unsaturated, linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups, whether alicyclic, aromatic, or heterocyclic. Among these, preferred monovalent organic groups are substituted or unsubstituted monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, substituted or unsubstituted monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, substituted or unsubstituted monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof. Examples of other examples include groups having a chain structure or a cyclic structure in which some or all of the hydrogen atoms have been substituted with substituents, and groups containing CO, CS, O, S, SO, or NR', or a combination of two or more of these, between the carbon atoms of these groups. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0054] Examples of the substituent that substitutes some or all of the hydrogen atoms of the organic group include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; hydroxy groups; carboxy groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O).

[0055] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include R 1 Examples of the alicyclic hydrocarbon group include the monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, all of which are exemplified in 1. Among these, the alicyclic hydrocarbon group is preferably a monovalent monocyclic alicyclic group having 3 to 10 carbon atoms or a monovalent polycyclic alicyclic group having 6 to 14 carbon atoms.

[0056] Examples of the heterocyclic cyclic hydrocarbon group include a group in which one hydrogen atom has been removed from an aromatic heterocyclic structure and a group in which one hydrogen atom has been removed from an alicyclic heterocyclic structure. Five-membered aromatic structures that have aromaticity due to the introduction of heteroatoms are also included in the heterocyclic structure. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0057] Examples of the aromatic heterocyclic structure include: Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; nitrogen atom-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms, such as thiazole, benzothiazole, thiazine, and oxazine.

[0058] Examples of the alicyclic heterocyclic structure include Oxygen atom-containing alicyclic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; Nitrogen atom-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thietane, thiolane, and thiane; Examples include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0059] Examples of the cyclic structure include a lactone structure, a cyclic carbonate structure, a sultone structure, and a structure containing a cyclic acetal, such as those represented by the following formulas (H-1) to (H-10).

[0060] [ka]

[0061] In the above formula, m is an integer of 1 to 3.

[0062] Above R 8b and R 9b The 3-20-membered ring structure formed by combining these together with the carbon atoms to which they are bonded is preferably an alicyclic monocyclic structure having 3-10 carbon atoms, an alicyclic polycyclic structure having 6-14 carbon atoms, or an aromatic ring structure having 8-20 carbon atoms. The alicyclic monocyclic structure having 3-10 carbon atoms and the alicyclic polycyclic structure having 6-14 carbon atoms may be either a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. The alicyclic polycyclic structure may be either a bridged alicyclic hydrocarbon structure or a fused alicyclic hydrocarbon structure. Note that a fused alicyclic hydrocarbon structure refers to a polycyclic alicyclic hydrocarbon structure formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0063] Among the alicyclic monocyclic structures, preferred saturated hydrocarbon structures include cyclopentane, cyclohexane, cycloheptane, and cyclooctane, and preferred unsaturated hydrocarbon structures include cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene. Preferred alicyclic polycyclic structures include bridged alicyclic saturated hydrocarbon structures, such as bicyclo[2.2.1]heptane (norbornane), bicyclo[2.2.2]octane, and tricyclo[3.3.1.1]. 3,7 ] Decane (adamantane) and the like are preferred.

[0064] Examples of the aromatic ring structure having 8 to 20 carbon atoms include indene, fluorene, and xanthene.

[0065] n4 is preferably an integer of 1 to 3, more preferably 1 or 2, and particularly preferably 1.

[0066] Compound (1) is represented by the above formula (1-2), and f1 and R f2 are each independently a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, and R 1 and R 2 is a hydrogen atom, n1 and n2 are 1, n3 is 0, and n4 is 1; X 1 and X 2 is preferably an oxygen atom. When compound (1) has this structure, it is possible to improve the sensitivity, LWR performance, and CDU performance.

[0067] Specific examples of compound (1-1) include, but are not limited to, onium salt compounds represented by the following formulas (1-1-1) to (1-1-32) (hereinafter, the onium salt compounds represented by the following formulas (1-1-1) to (1-1-32) may also be referred to as "compound (1-1-1) to compound (1-1-32)").

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] In the above formulas (1-1-1) to (1-1-32), Z + is a radiation-sensitive onium cation.

[0072] Specific examples of compound (1-2) include, but are not limited to, the following formulae (1-2-1) to (1-2-86) (hereinafter, the onium salt compounds represented by the following formulae (1-2-1) to (1-2-86) are also referred to as "compound (1-2-1) to compound (1-2-86)").

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] In the above formulas (1-2-1) to (1-2-86), Z + is a radiation-sensitive onium cation.

[0079] The compounds (1-1-1) to (1-1-32) and the compounds (1-2-1) to (1-2-86) are onium salt compounds having one specific partial structure. The compounds (1-2-80) and the compounds (1-2-83) to (1-2-86) are compounds that can be polymerized with other acrylate monomers, hydroxystyrene monomers, or the like, as needed, to give a resin form (acid-generating resin) having the specific partial structure as part of the resin.

[0080] Examples of the onium salt compound having two specific partial structures include compounds represented by the following formulas (1-3-1) to (1-3-2).

[0081] [ka]

[0082] The content of compound (1) in compound form (when compound (1) is used in combination, the total of the two) is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the resin described below. The content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. The content of resin-form compound (1) is the amount in which the resin in compound form is replaced with an acid-generating resin, and the content of other components may be defined as the amount per 100 parts by mass of the acid-generating resin. The content of compound (1) is appropriately selected depending on the type of resin used, exposure conditions, desired sensitivity, and the type and content of the radiation-sensitive acid generator described below. This allows for excellent sensitivity, LWR performance, and CDU performance to be exhibited during resist pattern formation.

[0083] (Method for synthesizing compound (1)) As a method for synthesizing compound (1), compound (1-2) (in the above formula (1-2), X 1 and X 2Here, we will explain the case where n is an oxygen atom and n4 is 1. As shown in the following scheme, a dihydroxycarboxylic acid is first converted into an ester, and then the diol of this ester is reacted with a ketone to form an acetal. This is then hydrolyzed with an appropriate alkali (lithium hydroxide in the scheme below) to form a carboxylic acid, which is then finally esterified with a hydroxyonium salt compound to synthesize the target compound (1-2a).

[0084] [ka]

[0085] In the above scheme, R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8b , R 9b , n1, n2, n3 and Z + is the same as in the above formula (1). 101 is an alkyl group.

[0086] As a method for synthesizing compound (1), compound (1-1) (in the above formula (1-1), X 1 and X 2 are both oxygen atoms, and R 8a and R 9a Here, the case where both are acyl groups will be explained as an example. Typically, as shown in the following scheme, a diester is first formed between the hydroxy group of the ester obtained in the synthesis scheme of compound (1-2) and a carboxylic acid. Furthermore, a triester is formed between the hydroxy group of the diester and a carboxylic acid halide (chloride in the scheme). Next, this is hydrolyzed with an appropriate alkali (lithium hydroxide in the scheme below) to form a diester carboxylic acid, and finally, the target compound (1-1a) can be synthesized by esterification with a hydroxy onium salt compound.

[0087] [ka]

[0088] In the above scheme, R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , n1, n2, n3 and Z + is the same as in the above formula (1). 101 is an alkyl group. 102 and R 103 is a monovalent organic group.

[0089] Compounds (1) having other structures can also be synthesized in the same manner by appropriately selecting precursors corresponding to the anion moiety and the onium cation moiety.

[0090] (resin) The resin is an aggregate of polymers having a structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (I)") (hereinafter also referred to as "base resin"). 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 radiation-sensitive resin composition has excellent pattern formability because the resin contains the structural unit (I).

[0091] In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may also have structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0092] Structural Units The structural unit (I) is a structural unit containing an acid-dissociable group. 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 resin composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0093] [ka]

[0094] In the above formula (3), R 17 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 18 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 19 and R 20 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.

[0095] Above R 17 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0096] Above R 18 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.

[0097] Above R 18 ~R 20Examples 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.

[0098] Above R 18 ~R 20 Examples of the 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. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0099] Above R 18 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples thereof include aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl groups; and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0100] Above R 18 As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0101] Above R 19 and R 20The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula (I) 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).

[0102] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Preferred polycyclic alicyclic hydrocarbon groups include bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1]heptane-2,2-diyl. 3,7 ]Decane-2,2-diyl group (adamantane-2,2-diyl group) and the like are preferred.

[0103] Among these, R 18 is an alkyl group having 1 to 4 carbon atoms, and R 19 and R 20 are combined with each other, and the alicyclic structure formed together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure.

[0104] Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0105] [ka]

[0106] In the above formulas (3-1) to (3-6), R 17 ~R 20 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.

[0107] i and j are preferably 1. 18 R is preferably a methyl group, an ethyl group, or an isopropyl group. 19 and R 20 As the alkyl group, a methyl group or an ethyl group is preferred.

[0108] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0109] The content of the structural unit (I) (the total content when multiple types are included) relative to all structural units constituting the base resin is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0110] [Structural unit (II)] The structural unit (II) 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 (II), 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.

[0111] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10).

[0112] [ka]

[0113] In the above formula, R L1 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.

[0114] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded include R 19 and R 20 Examples include divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula (I) together with the carbon atoms to which they are bonded, and which have 3 to 8 carbon atoms. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0115] 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-.

[0116] Of these, the structural unit (II) 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.

[0117] The content of the structural unit (II) is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 35 mol% or more, based on all structural units constituting the base resin. It is also preferably 75 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less. By setting the content of the structural unit (II) 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.

[0118] [Structural unit (III)] The base resin optionally contains other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding those corresponding to the structural unit (II)). By further containing 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. 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.

[0119] Examples of the structural unit (III) include structural units represented by the following formula:

[0120] [ka]

[0121] In the above formula, R Ais a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0122] When the base resin has the structural unit (III) having the polar group, the content of the structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, based on the total structural units constituting the base resin. Also, the content is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content of the structural unit (III) within the above range, the lithography performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0123] Structural Unit (IV) In addition to the structural unit (III) having the polar group, the base resin optionally contains a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of these are collectively referred to as "structural unit (IV)"). The structural unit (IV) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This resin is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. In this case, the resin preferably contains the structural unit (I) in addition to the structural unit (IV).

[0124] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-labile group, and then to obtain structural unit (IV) by deprotection through hydrolysis. The structural unit that gives structural unit (IV) upon hydrolysis is preferably represented by the following formula (4-1) or (4-2).

[0125] [ka]

[0126] In the above formulas (4-1) and (4-2), R 11is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 12 The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0127] Above R 12 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0128] In the case of a resin intended for exposure to radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total structural units constituting the resin, and is preferably 70 mol % or less, more preferably 60 mol % or less.

[0129] (Method for synthesizing base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0130] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical initiators can be used alone or in combination of two or more.

[0131] Examples of the solvent used in the polymerization include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0132] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0133] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin as converted to polystyrene by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the base resin is below the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is above the upper limit, the developability of the resist film may be reduced.

[0134] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as 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.

[0135] The Mw and Mn of the resin in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.

[0136] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0137] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0138] (other resins) The radiation-sensitive resin composition of this embodiment may contain, as an additional 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, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0139] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have the structural unit (I) or the structural unit (II) in the above base resin, as necessary.

[0140] [ka]

[0141] In the above formula (5), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. 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.

[0142] Above R 13 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.

[0143] 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.

[0144] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula 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.

[0145] Above R 14 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.

[0146] Above R 14 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0147] When the high-fluorine-content resin has the structural unit (V), the content of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, based on the total structural units constituting the high-fluorine-content resin. Also, the content is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0148] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V): By having the structural unit (f-2), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0149] [ka]

[0150] The structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0151] When the structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (x) an alkali-soluble group, it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (VI) having (x) an alkali-soluble group, A 1 is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0152] When the structural unit (VI) has an alkali-dissociable group (y), R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1or R F is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (y) an alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (VI) having (y) an alkali-dissociable group, A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0153] R C As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0154] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0155] When the high-fluorine-content resin has the structural unit (VI), the content of the structural unit (VI) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on all structural units constituting the high-fluorine-content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0156] Other structural units The high fluorine content resin may contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the structural units listed above. [ka] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0157] In the above formula (6), R 2α The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) is 8 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and represented by the following formula can be suitably used.

[0158] When the high-fluorine-content resin contains the structural unit having the alicyclic structure, the content of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total structural units constituting the high-fluorine-content resin, and is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less.

[0159] The Mw of the high fluorine content resin is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0160] The Mw / Mn of the high fluorine content resin is usually 1 or more, more preferably 1.1 or more, and usually 5 or less, preferably 3 or less, more preferably 2 or less, and even more preferably 1.9 or less.

[0161] The content of the high-fluorine content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base resin, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0162] By setting the content of the high-fluorine-containing resin within the above range, the high-fluorine-containing resin can be more effectively distributed unevenly on the surface layer of the resist film, thereby further improving the water repellency of the surface of the resist film during immersion lithography. The radiation-sensitive resin composition may contain one or more high-fluorine-containing resins.

[0163] (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.

[0164] (acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion controller. The acid diffusion controller controls the diffusion of the acid generated from compound (1) in the resist film upon exposure, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the exposure time between exposure and development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0165] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0166] [ka]

[0167] In the above formula (7), R 22 , R 23 and R 24 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0168] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0169] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0170] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide; and the like.

[0171] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0172] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0173] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0174] Furthermore, a compound having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, and Nt-amyloxycarbonyl-4-hydroxypiperidine.

[0175] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can also be suitably used as the acid diffusion controller. The acid generated by the radiation-sensitive acid generator is a weak acid that does not induce dissociation of the acid-dissociable group in the resin under conditions that dissociate the acid-dissociable group. In this specification, "dissociation" of the acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.

[0176] Examples of the radiation-sensitive weak acid generator include onium salt compounds that decompose upon exposure to light and lose their ability to control acid diffusion. Examples of the onium salt compound include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2).

[0177] [ka]

[0178] In the above formula (8-1) and formula (8-2), J + is a sulfonium cation, and U + is the iodonium cation. + Examples of the sulfonium cation represented by the formula (X-1) to (X-3) include the sulfonium cation represented by the formula (X-1) to (X-3), and U + Examples of the iodonium cation represented by the formula (X-4) to (X-5) include the iodonium cation represented by the formula (X-4) to (X-5). - and Q - are each independently OH - , R α -COO - , R α -SO3 - It is an anion represented by R α is an alkyl group, an aryl group, or an aralkyl group. α A hydrogen atom in the aromatic ring of the aryl group or aralkyl group represented by the following formula may be substituted with a hydroxy group, a fluorine atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0179] Examples of the radiation-sensitive weak acid generator include compounds represented by the following formula:

[0180] [ka]

[0181] Of these, the radiation-sensitive weak acid generator is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate or triphenylsulfonium 10-camphorsulfonate.

[0182] The content of the acid diffusion controller is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the total amount of the radiation-sensitive acid generator, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 110 parts by mass or less.

[0183] By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion controller.

[0184] (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 Compound (1) and the resin, as well as the radiation-sensitive acid generator and other components that may be optionally contained therein.

[0185] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0193] (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.

[0194] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which causes a crosslinking reaction in the resin component by an acid catalyst reaction in the bake step after the floodwise exposure step, thereby increasing the molecular weight of the resin component and reducing the solubility of the patternwise exposed areas in a developer. Examples of the functional groups include (meth)acryloyl groups, hydroxymethyl groups, alkoxymethyl groups, epoxy groups, and vinyl ether groups.

[0195] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds having a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0196] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0197] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, and vinylene carbonate.

[0198] The nitrile compound may, for example, be succinonitrile.

[0199] The polyhydric alcohol may, for example, be glycerin.

[0200] The content of the uneven distribution accelerator is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and still more preferably 25 parts by mass or more, relative to 100 parts by mass of the total amount of resin in the radiation-sensitive resin composition. The content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more uneven distribution accelerators.

[0201] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.) The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0202] (alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

[0203] Examples of the alicyclic skeleton-containing compound include: Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0204] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0205] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0206] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing compound (A), a resin, a radiation-sensitive acid generator, and optionally a high-fluorine-content resin, and a solvent 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.

[0207] <Pattern formation method> A pattern forming method according to one embodiment of the present invention 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"); The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0208] According to the above-described resist pattern forming method, a high-quality resist pattern can be formed because the above-described radiation-sensitive resin composition, which exhibits excellent sensitivity in the exposure step, LWR performance, and CDU performance, is used. Each step will now be described.

[0209] [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.

[0210] 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.

[0211] When the next 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) and (IV) as the base resin in the composition.

[0212] [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.

[0213] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser (wavelength 193 nm), water is preferred for its availability and ease of handling, in addition to the above considerations. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0214] 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.

[0215] [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.

[0216] 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.

[0217] 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 resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As ether solvents, glycol ether solvents are preferred, with ethylene glycol monomethyl ether and propylene glycol monomethyl ether being more preferred. As ester solvents, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As ketone solvents, 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.

[0218] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer, and can be appropriately selected depending on whether the desired pattern is a positive or negative pattern.

[0219] 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]

[0220] 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.

[0221] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the resin (including the acid-generating resin) were measured under the conditions described above, and the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0222] [ 13 C-NMR analysis] Resin 13 C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0223] <Synthesis of Compound (1)> [Synthesis Example 1] (Synthesis of Compound (B-1)) Compound (B-1) was synthesized according to the following synthesis scheme.

[0224] [ka]

[0225] 20.0 mmol of glyceric acid, 1.00 mmol of concentrated sulfuric acid, and 50 g of methanol were added to a reaction vessel and stirred at 100°C for 12 hours. Subsequently, saturated aqueous sodium bicarbonate solution was added to terminate the reaction, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain the ester in good yield.

[0226] To the above ester, 20.0 mmol of 2-adamantanone, 1.00 mmol of concentrated sulfuric acid, and 50 g of toluene were added, followed by stirring at 150°C for 4 hours. The reaction was then terminated by adding saturated aqueous sodium bicarbonate, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain the acetal in good yield.

[0227] A mixture of acetonitrile and water (1:1 (mass ratio)) was added to the above acetal to prepare a 1 M solution, and then 20.0 mmol of lithium hydroxide was added and the mixture was allowed to react at room temperature for 4 hours. Then, 1 M hydrochloric acid was added to make the system acidic, and methylene chloride was added for extraction, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was distilled off, and the carboxylic acid was obtained in good yield.

[0228] To the carboxylic acid compound, 20.0 mmol of triphenylsulfonium 1,1-difluoro-2-hydroxymethane-1-sulfonate, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride were added, and the mixture was allowed to react at room temperature for 5 hours. After dilution with water, the mixture was extracted with methylene chloride and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain compound (B-1) represented by formula (B-1) in good yield.

[0229] [Synthesis Examples 2 to 22] (Synthesis of Compounds (B-2) to (B-22)) Compounds (1) represented by the following formulae (B-2) to (B-22) were synthesized in the same manner as in Synthesis Example 1, except that the raw materials and precursors were appropriately changed. The compounds represented by the following formulae (B-21) to (B-22) were used to synthesize acid-generating resins.

[0230] [ka]

[0231] [Synthesis Example 23] (Synthesis of compound (B-23)) Using the aforementioned ester as a raw material, compound (B-23) was synthesized according to the following synthesis scheme.

[0232] [ka]

[0233] A reaction vessel was charged with 20.0 mmol of the aforementioned ester, 20.0 mmol of pivalic acid, 20.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride, and the mixture was allowed to react at room temperature for 5 hours. After dilution with water, the mixture was extracted with methylene chloride and the organic layer was separated. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the mixture was purified by column chromatography to obtain the diester in good yield.

[0234] To the diester, 20.0 mmol of 1-adamantanecarbonyl chloride, 20.0 mmol of triethylamine, and 50 g of acetonitrile were added and stirred at room temperature for 12 hours. The reaction was then terminated by adding saturated aqueous ammonium chloride, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the mixture was purified by column chromatography to obtain the triester in good yield.

[0235] A mixture of acetonitrile and water (1:1 (mass ratio)) was added to the triester to prepare a 1M solution, and then 15.0 mmol of lithium hydroxide was added and the mixture was allowed to react at room temperature for 1 hour. Then, 1M hydrochloric acid was added to make the system acidic, and methylene chloride was added for extraction, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was distilled off, and the diester carboxylic acid was obtained in good yield.

[0236] To the diester carboxylic acid product, 15.0 mmol of triphenylsulfonium 1,1-difluoro-2-hydroxymethane-1-sulfonate, 25.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride were added, and the mixture was allowed to react at room temperature for 5 hours. After dilution with water, the mixture was extracted with methylene chloride and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain compound (B-23) represented by formula (B-23) in good yield.

[0237] [Synthesis Examples 24 to 31] (Synthesis of compounds (B-24) to (B-31)) Compounds (1) represented by the following formulae (B-24) to (B-31) were synthesized in the same manner as in Synthesis Example 23, except that the raw materials and precursors were changed as appropriate.

[0238] [ka]

[0239] [Radiation-sensitive acid generators other than compounds (B-1) to (B-31)] b-1 to b-15: Compounds represented by the following formulas (b-1) to (b-15) (hereinafter, the compounds represented by formulas (b-1) to (b-15) may be referred to as "compound (b-1)" to "compound (b-15)", respectively.)

[0240] [ka]

[0241] <Synthesis of resin and high fluorine content resin> The monomers used in the synthesis of each resin and high-fluorine content resin 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 taken as 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is taken as 100 mol %.

[0242] [ka]

[0243] [Synthesis Example 32] (Synthesis of Resin (A-1)) Monomer (M-1), monomer (M-2), and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% relative to the total of 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered, and dried at 50°C for 24 hours to obtain a white powdery resin (A-1) (yield: 83%). The Mw of the resin (A-1) was 8,800, and the Mw / Mn was 1.50. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2) and (M-13) were 41.3 mol %, 13.8 mol % and 44.9 mol %, respectively.

[0244] [Synthesis Examples 33 to 42] (Synthesis of Resin (A-2) to Resin (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. The content (mol %) of each structural unit, the yield (%), and physical properties (Mw and Mw / Mn) of the resulting resins are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used (the same applies to the following tables).

[0245] [Table 1]

[0246] [Synthesis Example 43] (Synthesis of Acid-Generating Resin (B-32)) Monomer (M-1), monomer (M-2), monomer (M-5), and monomer (B-22) were dissolved in 2-butanone (200 parts by mass) in a molar ratio of 40 / 10 / 45 / 5 (mol%), and AIBN (azobisisobutyronitrile) (6 mol% relative to the total of 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered, and dried at 50°C for 24 hours to obtain a white powdery resin (A-12) (yield: 72%). The acid-generating resin (B-32) had an Mw of 5,600 and an Mw / Mn ratio of 1.61. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2), (M-5) and (B-22) were 41.3 mol%, 9.1 mol%, 45.6 mol% and 4.0 mol%, respectively.

[0247] [Synthesis Examples 44-45] (Synthesis of Acid-Generating Resin (B-33) to Acid-Generating Resin (B-34)) Acid-generating resins (B-33) to (B-34) were synthesized in the same manner as in Synthesis Example 12, except that the types and blending ratios of monomers shown in Table 2 were used. The content ratio (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained acid-generating resins are also shown in Table 2.

[0248] [Table 2]

[0249] [Synthesis Example 46] (Synthesis of Resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) at a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the mixture was stirred at 70°C for 6 hours to carry out a hydrolysis reaction. After the reaction was completed, the remaining solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the resin. The resulting solid was filtered and dried at 50°C for 13 hours to obtain white powdery resin (A-12) (yield: 79%). The Mw of resin (A-15) was 5,200, and the Mw / Mn ratio was 1.60. Furthermore, 13C-NMR analysis revealed that the content ratios of structural units derived from (M-1) and (M-18) were 51.3 mol% and 48.7 mol%, respectively.

[0250] [Synthesis Examples 47 to 51] (Synthesis of Resin (A-13) to Resin (A-15) and Acid-Generating Resin (B-35) to Acid-Generating Resin (B-36)) Resins (A-13) to (A-15) and acid-generating resins (B-35) to (B-36) were synthesized in the same manner as in Synthesis Example 46, except that the types and blending ratios of monomers shown in Table 3 below were used. The content (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained resins and acid-generating resins are also shown in Table 3 below.

[0251] [Table 3]

[0252] [Synthesis Example 52] (Synthesis of high fluorine content resin (E-1)) Monomer (M-1) and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was added to a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerized 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 process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of high-fluorine-content resin (E-1) (yield: 69%). The high fluorine content resin (E-1) had an Mw of 6,000 and an Mw / Mn ratio of 1.62. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.

[0253] [Synthesis Examples 53 to 56] (Synthesis of High Fluorine Content Resin (E-2) to High Fluorine Content Resin (E-5)) High fluorine content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 52, except for using monomers of the types and blending ratios shown in Table 3 below. The content (mol %) of each structural unit, yield (%) and physical properties (Mw and Mw / Mn) of the obtained high fluorine content resins are also shown in Table 4 below.

[0254] [Table 4]

[0255] [[C] Acid diffusion control agent] C-1 to C-5: Compounds represented by the following formulas (C-1) to (C-5)

[0256] [Chemical formula]

[0257] [Solvent [D]] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-Butyrolactone D-4: Ethyl lactate

[0258] [Preparation of positive radiation-sensitive resin composition for ArF lithography] [Example 1] [100 parts by mass of (A-1) as the resin, 12.0 parts by mass of (B-1) as the compound (1), 3.0 parts by mass of (C-1) as the acid diffusion control agent, 3.0 parts by mass (solid content) of (E-1) as the high fluorine content resin, and 3,230 parts by mass of the mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D] were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare the radiation-sensitive resin composition (J-1).]

[0259] [Examples 2 to 57 and Comparative Examples 1 to 15] [Except for using the components of the types and contents shown in Table 5 below, the radiation-sensitive resin compositions (J-2) to (J-57) and (CJ-1) to (CJ-15) were prepared in the same manner as in Example 1.]

[0260] [Table 5]

[0261] [Formation of resist pattern using positive radiation-sensitive resin composition for ArF lithography] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 100 nm. The positive radiation-sensitive resin composition for ArF exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by pre-baking at 100°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7) through a 40 nm line-and-space mask pattern. After exposure, PEB (post-exposure bake) was performed for 60 seconds at 100° C. Then, the resist film was alkaline-developed using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and further dried to form a positive resist pattern (40 nm line and space pattern).

[0262] <Evaluation> The resist patterns formed using the above-mentioned positive radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity and LWR performance according to the following methods. The results are shown in Table 6. The resist patterns were measured using a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation).

[0263] [sensitivity] In forming a resist pattern using the positive radiation-sensitive resin composition for ArF exposure, the exposure dose required to form a 40 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm2). 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0264] [LWR performance] A 40 nm line-and-space resist pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation above. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 3.0 nm or less, and "poor" when it exceeded 3.0 nm.

[0265] [Table 6]

[0266] As is clear from the results in Table 6, the radiation-sensitive resin compositions of the Examples exhibited good sensitivity and LWR performance when used in ArF exposure, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive resin compositions of the Examples are used in ArF exposure, resist patterns with high sensitivity and good LWR performance can be formed.

[0267] [Preparation of Positive-Working Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 58] A radiation-sensitive resin composition (J-58) was prepared by mixing 100 parts by mass of (A-12) as the resin [A], 15.0 parts by mass of (B-7) as the compound (1) [B], 4.0 parts by mass of (C-2) as the acid diffusion controller [C], 3.0 parts by mass (solids content) of (E-5) as the high fluorine content resin [E], and 6,110 parts by mass of the mixed solvent of (D-1) / (D-4) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0268] [Examples 59 to 70 and Comparative Examples 16 to 19] Radiation-sensitive resin compositions (J-59) to (J-70) and (CJ-16) to (CJ-19) were prepared in the same manner as in Example 58, except that the types and amounts of each component shown in Table 7 below were used.

[0269]

Table 7

[0270] <Formation of a resist pattern using a positive radiation-sensitive resin composition for EUV lithography> On a 12-inch silicon wafer, a composition for forming an anti-reflection film (ARC66 from Brewer Science) was applied using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflection film with an average thickness of 105 nm. The prepared positive radiation-sensitive resin composition for EUV lithography was applied onto this anti-reflection film using the spin coater, and PB was performed at 130°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 55 nm was formed. Next, this resist film was exposed using an EUV exposure apparatus (NXE3300 from ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive resist pattern (32 nm line and space pattern).

[0271] <Evaluation> Regarding the resist pattern formed using the above positive radiation-sensitive resin composition for EUV lithography, the sensitivity and LWR performance were evaluated according to the following method. The results are shown in Table 8 below. For measuring the length of the resist pattern, a scanning electron microscope (CG-5000 from Hitachi High-Technologies Corporation) was used.

[0272] [Sensitivity] In forming a resist pattern using the positive-tone radiation-sensitive resin composition for EUV exposure, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 30 mJ / cm 2 The following are considered "good" and 30mJ / cm 2 If it exceeded this, it was rated as "poor".

[0273] [LWR performance] A resist pattern was formed by irradiating the substrate with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 32 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR performance was evaluated as "good" when it was 3.5 nm or less, and "poor" when it exceeded 3.5 nm.

[0274] [Table 8]

[0275] As is clear from the results in Table 8, the radiation-sensitive resin compositions of the Examples had good sensitivity and LWR performance when used for EUV exposure, whereas the Comparative Examples were inferior in each property to the Examples.

[0276] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 71] A radiation-sensitive resin composition (J-71) was prepared by mixing 100 parts by mass of (A-6) as the resin [A], 12.0 parts by mass of (B-8) as the compound (1), 4.0 parts by mass of (C-5) as the acid diffusion controller [C], 5.0 parts by mass (solids content) of (E) as the high fluorine content resin [E-3], and 3,230 parts by mass of the mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0277] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 100 nm. The negative radiation-sensitive resin composition for ArF exposure (J-71) prepared above was then coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 100°C for 60 seconds. The coating was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a mask pattern with 40 nm holes and a 105 nm pitch. After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 100° C. Then, the resist film was developed using n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0278] <Evaluation> The CDU performance of the resist patterns formed using the negative radiation-sensitive resin composition for ArF exposure was evaluated according to the following method. The resist pattern dimensions were measured using a scanning electron microscope (CG-5000, manufactured by Hitachi High-Technologies Corporation).

[0279] [CDU performance] A resist pattern with 40 nm holes and a 105 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the above-mentioned scanning electron microscope. The dimensional variation (3σ) was calculated and used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better performance.

[0280] The resist patterns formed using the negative-tone radiation-sensitive resin compositions for ArF exposure were evaluated as described above. As a result, the radiation-sensitive resin composition of Example 71 exhibited good sensitivity and CDU performance even when a negative-tone resist pattern was formed by ArF exposure.

[0281] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 72] A radiation-sensitive resin composition (J-72) was prepared by mixing 100 parts by mass of (A-13) as the resin [A], 21.0 parts by mass of (B-7) as the compound (1) [B], 5.0 parts by mass of (C-2) as the acid diffusion controller [C], 3.0 parts by mass (solids content) of (E-5) as the high fluorine content resin [E], and 6,110 parts by mass of the mixed solvent of (D-1) / (D-4) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0282] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for EUV exposure prepared above was then coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking 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 then exposed to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0283] The resist pattern formed using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern formed using the negative-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 72 had good sensitivity and CDU performance, even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0284] 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 excellent LWR and CDU performance, 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. An onium salt compound having a structure represented by the following formula (1-2): 【Chemical 1】 (In the above formula (1-2), R ｆ１ and R ｆ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R １ is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ２ , R ５ , R ６ and R ７ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n １ is an integer of 1 or 2. ｆ１ and R ｆ２ If there are multiple R ｆ１ and R ｆ２ are the same or different from each other. n ２ is an integer from 0 to 4. １ and R ２ If there are multiple R １ and R ２ are the same or different from each other. However, n １ +n ２ is an integer from 2 to 6. n ３ is 0. X １ and X ２ are each independently an oxygen atom or a sulfur atom. * indicates a bond to another structure. Z ＋ is a monovalent radiation-sensitive onium cation. R ８ｂ and R ９ｂ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R ８ｂ and R ９ｂ represents a ring structure having 3 to 20 ring members formed by combining together with the carbon atoms to which they are attached. n ４ is 1.)

2. The above R ８ｂ and R ９ｂ and each of the organic groups represented by the formula (I) is independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

3. 3. The onium salt compound according to claim 2, wherein the alicyclic hydrocarbon group is a monovalent monocyclic alicyclic group having 3 to 10 carbon atoms or a monovalent polycyclic alicyclic group having 6 to 14 carbon atoms.

4. The above R ８ｂ and R ９ｂ and , when combined with each other, form a ring structure having 3 to 20 ring members, together with the carbon atoms to which they are bonded, which ring structure is an alicyclic monocyclic structure having 3 to 10 carbon atoms, an alicyclic polycyclic structure having 6 to 14 carbon atoms, or an aromatic ring structure having 8 to 20 carbon atoms.

5. 5. The onium salt compound according to claim 1, wherein the radiation-sensitive onium cation in the formula (1-2) is a sulfonium cation or an iodonium cation.

6. In the above formula, n ２ The onium salt compound according to any one of claims 1 to 5, wherein is an integer of 1 to 4.

7. In the above formula, n １ +n ２ The onium salt compound according to any one of claims 1 to 6, wherein

8. The above R ｆ１ and R ｆ２ are each independently a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, R １ and R ２ is a hydrogen atom, n １ and n ２ is 1, X １ and X ２ The onium salt compound according to any one of claims 1 to 4, wherein is an oxygen atom.

Images