Onium salt compounds

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] This invention relates to onium salt compounds. [Background technology]

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the resin in alkaline or organic developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

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

[0004] As efforts to further advance the technology progress, attempts are also being made to improve the sensitivity and resolution of photoacid generators, which are the main components of resist compositions. For example, an acid generator capable of imparting a strong acid by substituting the proximal carbon of the sulfonic acid group with fluorine is being investigated (Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-12684 [Overview of the project] [Problems that the invention aims to solve]

[0006] Among such efforts toward next-generation technologies, resist performance equivalent to or better than that of the conventional technology in terms of LWR (Line Width Roughness) performance, which indicates variations in sensitivity and line widths of resist patterns, CDU (Critical Dimension Uniformity) performance, etc. is required. However, such characteristics have not been obtained at a sufficient level with existing radiation-sensitive resin compositions.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition and a patterning method capable of exhibiting sensitivity, LWR performance, and CDU performance at a sufficient level.

Means for Solving the Problems

[0008] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0009] That is, in one embodiment, the present invention relates to an onium salt compound containing a structure represented by the following formula (1), a solvent, and a radiation-sensitive resin composition containing the same.

Chemical Formula

[0010] The radiation-sensitive resin composition contains an onium salt compound (hereinafter also referred to as "compound (1)") having the structure represented by formula (1) above as a radiation-sensitive acid generator, and can exhibit excellent sensitivity, LWR performance, and CDU performance during resist pattern formation. The reason for this is not bound by any theory, but can be inferred as follows: The electron-withdrawing group can strongly oxidize the generated acid by bonding an electron-withdrawing group to the carbon atom to which the sulfo group is bonded, and by introducing an ester bond and two adjacent (thio)ether structures to the skeleton, the diffusion length of the acid and its affinity with the resin can be set to an appropriate level, and the given resist performance can be exhibited through the synergistic effect of these. Note that an organic group refers to a group containing at least one carbon atom.

[0011] In another embodiment, the present invention includes the step of applying the radiation-sensitive resin composition directly or indirectly onto a substrate to form a resist film, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. This relates to a pattern formation method that includes [specific details].

[0012] This pattern formation method uses the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance, and CDU performance, thus enabling the efficient formation of high-quality resist patterns. [Modes for carrying out the invention]

[0013] The embodiments of the present invention will be described in detail below, 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") comprises compound (1) and a solvent. More preferably, it comprises a resin and, if necessary, an acid diffusion control agent. The above composition may contain other optional components as long as they do not impair the effects of the present invention. By including compound (1) as a radiation-sensitive acid generator, the radiation-sensitive resin composition can be given a high level of sensitivity LWR performance and CDU performance.

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

[0016] [ka]

[0017] In the above formula (1), R f1 and R f2 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 1 This 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 Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n1 is an integer between 0 and 4. f1 and R f2If there are multiple instances of each, then multiple R f1 and R f2 They are either identical or different from one another. n² is an integer between 0 and 4. 1 and R 2 If there are multiple instances of each, then multiple R 1 and R 2 They are either identical or different from one another. However, n1 + n2 is an integer between 2 and 8. n3 is an integer between 0 and 5. 3 and R 4 If there are multiple instances of each, then multiple R 3 and R 4 They are either identical or different from one another. X 1 and X 2 Each of these is independently either an oxygen atom or a sulfur atom. *Each symbol represents a connection with another structure. Z + It is a monovalent radiation-sensitive onium cation.

[0018] R f1 and R f2 Examples of monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as represented by , include monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0019] Examples of the above monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms include, for example, Fluorinated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoro-n-propyl group, heptafluoro-i-propyl group, nonafluoro-n-butyl group, nonafluoro-i-butyl group, nonafluoro-t-butyl group, 2,2,3,3,4,4,5,5-octafluoro-n-pentyl group, tridecafluoro-n-hexyl group, and 5,5,5-trifluoro-1,1-diethylpentyl group; Fluorinated alkenyl groups such as trifluoroethenyl groups and pentafluoropropenyl groups; Examples include fluorinated alkynyl groups such as fluoroethynyl groups and trifluoropropynyl groups.

[0020] Examples of the above-mentioned monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms include, for example, Fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, and fluorotetracyclodecyl group; Examples include fluorinated cycloalkenyl groups such as fluorocyclopentenyl groups and nonafluorocyclohexenyl groups.

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

[0022] R f1 and R f2 From the standpoint of the degree of freedom in the surrounding structure of the sulfo group and the acidity of the generated acid, a fluorine atom is preferred.

[0023] R 1 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0024] Examples of the above-mentioned monovalent linear hydrocarbon groups having 1 to 20 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms.

[0025] Examples of the above-mentioned alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or 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. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded by a bond chain containing one or more carbon atoms.

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

[0027] R 1 As a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms, R f1 and R f2 The monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as exemplified above, can be suitably used.

[0028] R 2 , R 3 , R 4 , R 5 , R 6 and R 7 As a monovalent hydrocarbon group having 1 to 20 carbon atoms, R 1 Monovalent hydrocarbon groups having 1 to 20 carbon atoms, as exemplified above, can be suitably used.

[0029] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 As such, hydrogen atoms or linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms are preferred, independently of each other. In particular, R 1and R 2 Preferably, both are hydrogen atoms.

[0030] n1 and n2 are each preferably integers between 1 and 4, more preferably between 1 and 3, and even more preferably 1 or 2. In particular, it is preferable that both n1 and n2 are 1.

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

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

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

[0034] In the above equation (1), the above Z + Examples of monovalent radiosensitive onium cations represented by the formulas (X-1) to (X-6) below include radiodegradable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, such as sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, sulfonium cations or iodonium cations are preferred. Sulfonium cations or iodonium cations are 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 equation (X-1), R a1 , R a2 and R a3 Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, 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 hydroxyl group, a halogen atom, and -OSO2-R. P , -SO2-R Q Alternatively, -SR T This represents a ring structure formed by combining two or more of these groups. This ring structure may contain heteroatoms such as O or S between the carbon-carbon bonds that form the skeleton. P , R Q and R T Each of these is 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 integers from 0 to 5. a1 ~R a3 R P , R Q and R TWhen there are a plurality of each, a plurality of R a1 ~R a3 as well as R P 、R Q and R T may be the same or different from each other.

[0042] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k When n is 0, k4 is an integer from 0 to 4, and n k When n is 1, k4 is an integer from 0 to 7. R b1 When there are a plurality of R, the plurality of R b1 may be the same or different from each other, and further, the plurality of R b1 may represent a ring structure formed by combining with each other. R b2 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. L C is a single bond or a divalent linking group. k5 is an integer from 0 to 4. R b2 / When there are a plurality of R, the plurality of R b2 may be the same or different from each other, and further, the plurality of R b2 may represent a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, the ring structure containing S + may contain heteroatoms such as O and S between the carbon-carbon bonds forming 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 g1This 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, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. k n is either 0 or 1. k2 When k10 is 0, k10 is an integer from 0 to 4, and n k2 When k10 is 1, k10 is an integer from 0 to 7. g1 If there are multiple, then multiple R g1 They may be the same or different, and there may be multiple R g1 R may represent a ring structure formed by combining with other elements. g2 is and R g3 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R g2 is and R g3 If each of them is multiple, then multiple R g2 is and R g3 These may be the same or different.

[0045] In the above equation (X-5), R d1 and R d2 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or 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, a nitro group, or a ring structure formed by two or more of these groups being combined. k6 and k7 are each independently integers from 0 to 5. d1 and R d2 If each of them is multiple, then multiple R d1 and R d2 These may be the same or different.

[0046] In the above equation (X-6), R e1 and R e2 k8 and k9 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.

[0047] Specific examples of radiation-sensitive onium cations include, but are not limited to, structures such as the one shown in the following formula.

[0048] [ka]

[0049] [ka]

[0050] Compound (1) is a structure that combines any anionic moiety containing a specific substructure with any radiation-sensitive onium cation.

[0051] When compound (1) is in compound form, it is preferable that the compound be 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 equations (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 + This is equivalent to equation (1) above. R 8a and R 9a Each of these is independently a monovalent organic group having 1 to 40 carbon atoms. R 8b and R 9b Each of these is independently either a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R 8b and R 9b These can be combined to form a ring structure with 3 to 20 members, along with the carbon atoms to which they bond. n4 is an integer between 1 and 4. 8b and R 9b If there are multiple instances of each, then multiple R 8b and R 9b They are either identical or different from each other.

[0053] R 8a , R 9a , R 8b and R 9b The monovalent organic group having 1 to 40 carbon atoms represented by 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 that are saturated or unsaturated, linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups that are 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. Also, groups in which some or all of the hydrogen atoms in a chain structure or a cyclic structure are substituted with substituents, and groups containing CO, CS, O, S, SO2, or NR', or a combination of two or more of these, between carbon atoms. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

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

[0055] The above monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the above monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the above monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms are R in formula (1) above. 1 Examples include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, respectively. Among these, the alicyclic hydrocarbon groups are preferably monovalent monocyclic alicyclic groups having 3 to 10 carbon atoms or monovalent polycyclic alicyclic groups having 6 to 14 carbon atoms.

[0056] Examples of the heterocyclic cyclic hydrocarbon groups mentioned above include groups obtained by removing one hydrogen atom from an aromatic heterocyclic structure and groups obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. Aromatic structures with five membered rings that acquire aromaticity by introducing heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0057] Examples of the above aromatic heterocyclic structures include, for example, Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur atom-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 above alicyclic heterocyclic structures include, for example, Oxygen atom-containing alicyclic heterocyclic structures such as oxiranes, tetrahydrofurans, tetrahydropyrans, dioxolanes, and dioxanes; Nitrogen-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thiethane, thiolane, and thian; Examples include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0059] Examples of cyclic structures include lactone structures, cyclic carbonate structures, sultone structures, and structures containing cyclic acetals. Such structures include, for example, those represented by the following formulas (H-1) to (H-10).

[0060] [ka]

[0061] In the above formula, m is an integer between 1 and 3.

[0062] The above R 8b and R 9b The ring structure with 3 to 20 members, formed by combining these rings with the carbon atoms to which they are bonded, is preferably an alicyclic monocyclic structure with 3 to 10 carbon atoms, an alicyclic polycyclic structure with 6 to 14 carbon atoms, or an aromatic ring structure with 8 to 20 carbon atoms. The alicyclic monocyclic structure with 3 to 10 carbon atoms and the alicyclic polycyclic structure with 6 to 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 condensed alicyclic hydrocarbon structure. A condensed alicyclic hydrocarbon structure refers to a polycyclic alicyclic hydrocarbon structure in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

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

[0064] Examples of aromatic ring structures with 8 to 20 carbon atoms include indene, fluorene, and xanthene.

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

[0066] Compound (1) is represented by the above formula (1-2), and the above R f1 and R f2 Each of these is 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, n4 is 1, X 1 and X 2 It is preferable that the atom is an oxygen atom. By having this structure in compound (1), sensitivity, LWR performance, and CDU performance can be improved.

[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, onium salt compounds represented by the following formulas (1-1-1) to (1-1-32) will also be referred to as "compound (1-1-1) to compound (1-1-32)").

[0068] [ka]

[0069] [ka]

[0070] [ka]

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

[0072] Specific examples of compound (1-2) include, but are not limited to, the following formulas (1-2-1) to (1-2-86) (hereinafter, onium salt compounds represented by the following formulas (1-2-1) to (1-2-86) will also be 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 equations (1-2-1) to (1-2-86), Z + It is a radiation-sensitive onium cation.

[0079] Compounds (1-1-1) to (1-1-32) and compounds (1-2-1) to (1-2-86) are onium salt compounds having one specific substructure. Compounds (1-2-80) and (1-2-83) to (1-2-86) can also be subjected to polymerization reactions with other acrylic acid ester monomers or hydroxystyrene monomers as needed to yield a resin form (acid-generating resin) having a specific substructure as part of the resin.

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

[0081] [ka]

[0082] The content of compound (1) in compound form (or the total content if compound (1) is used in combination) 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 later. The above 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 compound (1) in resin form is the amount obtained by replacing the resin in compound form with the acid-generating resin, and the content of other components may be specified as amounts 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, the exposure conditions and the required sensitivity, and the type and content of the radiation-sensitive acid generator described later. This allows for excellent sensitivity, LWR performance, and CDU performance during resist pattern formation.

[0083] (Method of synthesis of compound (1)) As a method for synthesizing compound (1), compound (1-2) (in the above formula (1-2), X 1 and X 2Let's take the case where both atoms are oxygen atoms and n4 is 1 as an example. Typically, as shown in the scheme below, first, the dihydroxycarboxylic acid is converted to an ester, and the diol of this ester is reacted with a ketone to form an acetal. Next, it is hydrolyzed with an appropriate alkali (lithium hydroxide in the scheme below) to obtain a carboxylic acid, and finally, the target compound (1-2a) can be synthesized by esterification with a hydroxyonium salt compound.

[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 + This is equivalent to equation (1) above. R 101 It 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 Both are oxygen atoms, R 8a and R 9a Let's take the case where both are acyl groups as an example. Typically, as shown in the scheme below, first, a diester is formed by combining the hydroxyl group of the ester obtained in the synthesis scheme of compound (1-2) with a carboxylic acid. Furthermore, a triester is formed by combining the hydroxyl group of the diester with a carboxylic acid halide (chloride in the scheme). Next, hydrolysis with an appropriate alkali (lithium hydroxide in the scheme below) yields a diester carboxylic acid, and finally, the target compound (1-1a) can be synthesized by esterification with a hydroxyonium 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 + This is equivalent to equation (1) above. R 101 R is an alkyl group. 102 and R 103 It is a monovalent organic group.

[0089] Compounds with other structures (1) can also be synthesized in a similar manner by appropriately selecting the precursors corresponding to the anionic and onium cation portions.

[0090] (resin) The resin is an aggregate of polymers having structural units containing acid-dissociable groups (hereinafter also referred to as "structural unit (I)") (hereinafter this resin is also referred to as the "base resin"). An "acid-dissociable group" is a hydrogen atom-substituting group such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group, which dissociates upon the action of an acid. The radiation-sensitive resin composition exhibits excellent pattern-forming properties because the resin contains structural unit (I).

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

[0092] [Structural Unit (I)] Structural unit (I) is a structural unit containing an acid-dissociable group. Structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples 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 replaced by a tertiary alkyl group, and a structural unit having an acetal bond. However, from the viewpoint of improving the pattern-forming properties 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 equation (3), R 17 R 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 Each of these independently represents either a monovalent linear 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 with the carbon atoms to which they are bonded.

[0095] The above R 17 From the viewpoint of copolymerization of the monomer that gives structural unit (I-1), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0096] The above R 18 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include chain hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0097] The above R 18 ~R 20Examples of chain-like hydrocarbon groups having 1 to 10 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.

[0098] The above R 18 ~R 20 Examples of alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include monocyclic or polycyclic saturated hydrocarbon groups, or 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. A bridged alicyclic hydrocarbon group is a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded by a bond chain containing one or more carbon atoms.

[0099] The above R 18 Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, represented by this formula, include: Examples include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthyl groups; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0100] The above R 18 Preferred carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0101] The above R 19 and R 20A divalent alicyclic group having 3 to 20 carbon atoms, formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by the above formula with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon of the above carbon number. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and as a polycyclic hydrocarbon group, it may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. A condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

[0102] Among 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. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, 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 3,7 A decane-2,2-diyl group (adamantane-2,2-diyl group) is preferred.

[0103] Among these, R 18 R is an alkyl group having 1 to 4 carbon atoms. 19 and R 20 It is preferable that the alicyclic structure formed by combining these elements with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0104] Examples of structural units (I-1) include the 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 equations (3-1) to (3-6), R 17 ~R 20 This is equivalent to equation (3) above. i and j are independent integers between 1 and 4. k and l are 0 or 1.

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

[0108] The base resin may contain one or more structural units (I) in combination.

[0109] The content of structural unit (I) (total content if multiple types are included) 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, relative to the total structural units constituting the base resin. Furthermore, 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 structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive resin composition can be further improved.

[0110] [Structural Units (II)] Structural unit (II) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising structural unit (II), the solubility of the base resin in the developer can be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

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

[0112] [ka]

[0113] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. L4 and R L5 These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and formed 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 from 0 to 3. m is an integer from 1 to 3.

[0114] The above R L4 and R L5 When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms that is formed together with the carbon atoms to which they are bonded is R in formula (3) above. 19 and R 20 Examples include divalent alicyclic groups with 3 to 8 carbon atoms, which are formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by , together with the carbon atoms to which they are bonded. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0115] The above L 2 Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0116] Among these, structural units (II) are preferably those containing a lactone structure, more preferably those containing a norbornane lactone structure, and even more preferably those derived from norbornane lactone-yl (meth)acrylate.

[0117] The content of structural unit (II) is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 35 mol% or more, relative to the total structural units constituting the base resin. Furthermore, it is preferably 75 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less. By setting the content of structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0118] [Structural Unit (III)] The base resin may optionally contain other structural units in addition to the structural units (I) and (II) described above. Examples of these other structural units include structural unit (III) containing a polar group (excluding those corresponding to structural unit (II)). By further containing structural unit (III), the solubility of the base resin in the developer can be adjusted, and as a result, the lithographic performance such as resolution of the radiation-sensitive resin composition can be improved. Examples of these polar groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and sulfonamide groups. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.

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

[0120] [ka]

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

[0122] When the base resin has structural unit (III) having the polar group described above, the content of structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, relative to the total structural units constituting the base resin. Furthermore, it 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 structural unit (III) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0123] [Structural Units (IV)] The base resin may optionally contain structural units other than the polar group-containing structural unit (III) described above, such as structural units derived from hydroxystyrene or structural units containing phenolic hydroxyl groups (hereinafter, both are collectively referred to as "structural unit (IV)"). Structural unit (IV) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelengths of 50 nm or less, such as electron beams and EUV. In this case, it is preferable that the resin contains structural unit (I) along with structural unit (IV).

[0124] In this case, it is preferable to polymerize the phenolic hydroxyl group while protecting it with a protecting group such as an alkali-dissociable group, and then deprotect it by hydrolysis to obtain structural unit (IV). The structural unit that gives structural unit (IV) by hydrolysis is preferably represented by the following formulas (4-1) and (4-2).

[0125] [ka]

[0126] In the above equations (4-1) and (4-2), R 11is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12 is a monovalent hydrocarbon group or an alkoxy group having 1 to 20 carbon atoms. R 12 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms for R 8 in Structural Unit (I) include the monovalent hydrocarbon group having 1 to 20 carbon atoms for R

[0127] Examples of the above R 12 include an alkyl group and an alkoxy group, and among them, a methyl group and a tert-butoxy group are more preferable.

[0128] In the case of a resin for exposure with radiation having a wavelength of 50 nm or less, the content ratio of Structural Unit (IV) is preferably 10 mol% or more, more preferably 20 mol% or more, based on all the structural units constituting the resin. Also, it is preferably 70 mol% or less, more preferably 60 mol% or less.

[0129] (Synthesis method of base resin) The base resin can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0130] Examples of the above radical polymerization initiators include azo-based 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), dimethyl 2,2'-azobisisobutyrate; peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferable, and AIBN is more preferable. These radical initiators can be used alone or in combination of two or more.

[0131] Examples of solvents used in the polymerization described above 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 include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. The solvent used in these polymerizations may be used alone or in combination of two or more.

[0132] The reaction temperature in the polymerization described above is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0133] The molecular weight of the base resin is not particularly limited, but a polystyrene-equivalent weight-average molecular weight (Mw) of 1,000 to 50,000 as determined by gel permeation chromatography (GPC) is 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 decrease. If the Mw of the base resin exceeds the upper limit, the developability of the resist film may decrease.

[0134] The ratio of Mw (Mw / Mn) to the polystyrene-equivalent number-average molecular weight (Mn) of the base resin, calculated by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

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

[0136] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Leaching 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 base resin content is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, relative to the total solid content of the radiation-sensitive resin composition.

[0138] (Other resins) The radiation-sensitive resin composition of this embodiment may also contain, as another resin, a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface of the resist film relative to the base resin, and as a result, the water repellency of the surface of the resist film during immersion exposure can be improved.

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

[0140] [Chemical formula]

[0141] In the above formula (5), R 13 is a hydrogen atom, a methyl group or a trifluoromethyl group. G L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. R 14 is a monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0142] [[ID=!8]]Regarding the above R 13 from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0143] Regarding the above G L from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferable, and -COO- is more preferable. <!

[0144] Regarding the above R 14 Examples of the monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms represented by the above R include those in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0145] Regarding the above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R include those in which some or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0146] Regarding the above R 14 is preferably a fluorinated linear hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably 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.

[0147] When a high-fluorine-content resin has structural units (V), the content of structural units (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, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, 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 structural units (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting the uneven distribution to 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] High-fluorine content resins may have fluorine atom-containing structural units (hereinafter also referred to as structural unit (VI)) represented by the following formula (f-2), either together with or in place of structural unit (V). The presence of structural unit (f-2) in high-fluorine content resins improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0149] [ka]

[0150] Structural units (VI) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates upon the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D This is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and the R of this hydrocarbon group E At the terminal end of the side are an oxygen atom, a sulfur atom, and -NR dd -, a structure to which a carbonyl group, -COO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are replaced by an organic group having a heteroatom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0151] If structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, A 1 * is an oxygen atom, -COO-* or -SO2O-*. F This shows the binding site. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 If is an oxygen atom, then W 1 is A 1 It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. E is a single bond or a divalent organic group with 1 to 20 carbon atoms. If s is 2 or 3, there are multiple R E , W 1 , A 1 and R F These may be the same or different. Having (x) an alkali-soluble group in structural unit (VI) increases its affinity for alkaline developer and suppresses development defects. A structural unit (VI) having (x) an alkali-soluble group is A 1 is an oxygen atom and W 1 It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0152] If structural unit (VI) has an alkali-dissociable group (y), R F A is a monovalent organic group having 1 to 30 carbon atoms. 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-* aa * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. F This shows the binding site. 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 If is -COO-* or -SO2O-*, then W 1or R F is A 1 It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. 1 If is an oxygen atom, then W 1 , R E It is a single bond, R D R is a hydrocarbon group with 1 to 20 carbon atoms. E It is a structure in which a carbonyl group is bonded to the terminal end, R F is an organic group containing a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F These may be the same or different. The presence of (y) an alkali-dissociable group in structural unit (VI) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural unit (VI) having (y) an alkali-dissociable group include A 1 is -COO-*, and R F Or W 1 Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0153] R C From the viewpoint of copolymerizability of the monomer that gives structural unit (VI), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

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

[0155] When a high-fluorine-content resin has structural units (VI), the content of structural units (VI) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, 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 structural units (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0156] [Other structural units] High-fluorine resins may also include structural units having an alicyclic structure represented by the following formula (6), in addition to the structural units listed above. [ka] (In the above formula (6), R 1α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

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

[0158] When a high-fluorine-content resin contains structural units having the above-mentioned alicyclic structure, the content of these structural units is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, it 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. Furthermore, it 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 ratio of high-fluorine-content resins is usually 1 or higher, more preferably 1.1 or higher. It is also usually 5 or lower, preferably 3 or lower, more preferably 2 or lower, and even more preferably 1.9 or lower.

[0161] The content of the high-fluorine 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, per 100 parts by mass of the base resin. Furthermore, it 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-content resin within the above range, the high-fluorine-content resin can be more effectively distributed to the surface layer of the resist film, and as a result, the water repellency of the surface of the resist film during immersion exposure can be further enhanced. The radiation-sensitive resin composition may contain one or more high-fluorine-content resins.

[0163] (Method for synthesizing high-fluorine content resins) High-fluorine-content resins can be synthesized by the same method as the base resin synthesis method described above.

[0164] (Acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion control agent. The acid diffusion control agent controls the diffusion phenomenon of the acid generated from compound (1) by exposure in the resist film, and has the effect of suppressing undesirable chemical reactions in the unexposed areas. In addition, the storage stability of the resulting radiation-sensitive resin composition is 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 holding time from exposure to development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

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

[0166] [ka]

[0167] In equation (7) above, R 22 , R 23 and R 24 Each of these is 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 nitrogen-containing compounds (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 nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

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

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

[0172] Examples of urea compounds include urea, methyl urea, 1,1-dimethyl urea, 1,3-dimethyl urea, 1,1,3,3-tetramethyl urea, 1,3-diphenyl urea, and tributylthiourea.

[0173] Examples of nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; and pyrazines and pyrazoles.

[0174] Furthermore, compounds having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of 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 be suitably used as an acid diffusion control agent. The acid generated by the above-mentioned radiation-sensitive acid generator is a weak acid that does not induce the dissociation of the acid-dissociable groups in the resin under conditions that would normally cause the dissociation of those groups. In this specification, "dissociation" of an acid-dissociable group refers to dissociation that occurs when post-exposure baking is performed at 110°C for 60 seconds.

[0176] Examples of radiation-sensitive weak acid generators include onium salt compounds that decompose upon exposure and lose their ability to control acid diffusion. Examples of onium salt compounds 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 equations (8-1) and (8-2), J + It is a sulfonium cation, U + This is an iodonium cation. + Examples of sulfonium cations represented by the above formulas (X-1) to (X-3) include U + Examples of iodonium cations represented by the above formulas (X-4) to (X-5) include iodonium cations represented by E - and Q - Each of them is independent of OH - , R α -COO - , R α -SO3 - This is an anion represented by R. α R is an alkyl group, an aryl group, or an aralkyl group. α The hydrogen atoms of the aromatic ring of the aryl or aralkyl group represented by may be substituted with a hydroxyl group, a fluorine-substituted or unsubstituted C1-C12 alkyl group, or a C1-C12 alkoxy group.

[0179] Examples of the above-mentioned radiation-sensitive weak acid generating agent include compounds represented by the following formula.

[0180] [ka]

[0181] Among the above-mentioned radiation-sensitive weak acid generating agents, sulfonium salts are preferred, triarylsulfonium salts are more preferred, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are even more preferred.

[0182] The acid diffusion control agent content 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, based on 100 parts by mass of the total amount of the radiation-sensitive acid generator. Furthermore, it 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 control agent 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 control agents.

[0184] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least compound (1) and the resin, as well as optionally contained radiation-sensitive acid generators, etc.

[0185] Examples of solvents 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 with 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 with 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 include polyhydric alcohol partial ether solvents, in which some of the hydroxyl groups of the above-mentioned polyhydric alcohol solvents have been etherified.

[0187] Examples of ether-based 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 (methylphenyl ether); Examples include polyhydric alcohol ether solvents, which are obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0188] Examples of ketone solvents include chain-like ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0189] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples include chain-like 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-based 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-based solvents such as γ-butyrolactone and valerolactone; Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polycarboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0191] Examples of hydrocarbon solvents include, for example, Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0192] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone 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 components) The above-mentioned radiation-sensitive resin composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, segregation promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used individually or in combination of two or more types.

[0194] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups. In the baking process after the batch exposure process, it causes a crosslinking reaction in the resin component via an acid-catalyzed reaction, increasing the molecular weight of the resin component and thereby reducing the solubility of the pattern exposure area in the developer. Examples of the functional groups include (meth)acryloyl groups, hydroxymethyl groups, alkoxymethyl groups, epoxy groups, vinyl ether groups, and the like.

[0195] (Urgent distribution agent) The segregation accelerator has the effect of more efficiently segregating the high-fluorine-content resin on the resist film surface. By including this segregation accelerator in the radiation-sensitive resin composition, the amount of 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 becomes possible to further suppress the elution of components from the resist film into the immersion medium and to perform immersion exposure at a higher speed by high-speed scanning, thereby improving the hydrophobicity of the resist film surface, which suppresses immersion-derived defects such as watermark defects. Examples of compounds that can be used as such segregation accelerators include low-molecular-weight compounds with a relative permittivity of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specifically, such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

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

[0197] Examples of the carbonate compounds mentioned above include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0198] Examples of the nitrile compounds mentioned above include succinonitrile.

[0199] Examples of the polyhydric alcohols mentioned above include glycerin.

[0200] The amount of the segregation 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 even more preferably 25 parts by mass or more, based on 100 parts by mass of the total amount of resin in the radiation-sensitive resin composition. Furthermore, it 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 types of segregation accelerators.

[0201] (Surfactants) Surfactants improve the properties of coating, striation, and development. 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 examples include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and No. 75. Examples include 95 (manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (manufactured by Tochem Products), Megafac F171, F173 (manufactured by DIC), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Industries), etc. The surfactant content in the above radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of resin.

[0202] (Alicyclic skeleton-containing compounds) Compounds containing alicyclic skeletons have the effect of improving dry etching resistance, pattern shape, and adhesion to the substrate.

[0203] Examples of alicyclic skeleton-containing compounds include, Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylic acid; Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholic acid 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 and 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane. The content of the alicyclic skeleton-containing compound in the above radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of resin.

[0204] (Sensitizer) The sensitizer increases the amount of acid produced from the radiation-sensitive acid generator, etc., and thus improves the "apparent sensitivity" of the above-mentioned 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 above-mentioned radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of resin.

[0206] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing compound (A), resin, radiation-sensitive acid generator, a high-fluorine-content resin if necessary, and a solvent in predetermined proportions. After mixing, the above radiation-sensitive resin composition is preferably filtered using a filter with a pore size of approximately 0.05 μm to 0.2 μm. The solid content concentration of the above 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 is: The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film formation step"), The above resist film is exposed in step (2) (hereinafter also referred to as the "exposure step"), The process includes (3) developing the exposed resist film (hereinafter also referred to as the "development step").

[0208] According to the above resist pattern formation method, a high-quality resist pattern can be formed because the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance, and CDU performance in the exposure process, is used. The following describes each step.

[0209] [Resist film formation process] In this step (step (1) above), a resist film is formed using the radiation-sensitive resin composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, with 80°C to 120°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred. The thickness of the formed resist film is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0210] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content resin in the above-mentioned radiation-sensitive resin composition, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0211] Furthermore, when the subsequent exposure process is carried out with radiation of a wavelength of 50 nm or less, it is preferable to use a resin having the above structural units (I) and (IV) as the base resin in the above composition.

[0212] [Synthesis process] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion medium such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0213] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorinated inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties 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 described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the resin, etc., by the acid generated from the radiation-sensitive acid generator during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[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, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0216] Examples of developers used in the above development process include, in the case of alkaline development, 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, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0217] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents. Examples of the above organic solvents 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 for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents 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 organic solvents in the developer include water and silicone oil.

[0218] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate choice can be made depending on whether a positive or negative pattern is desired.

[0219] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling up the developer solution on the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method). [Examples]

[0220] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0221] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the resins (including acid-generating resins) were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured Mw and Mn values.

[0222] [ 13 C-NMR analysis] resin 13 ¹

[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. Then, saturated sodium bicarbonate aqueous solution was added to stop the reaction, followed by extraction with ethyl acetate, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the ester was purified by column chromatography to obtain the ester in good yield.

[0226] 20.0 mmol of 2-adamantanone, 1.00 mmol of concentrated sulfuric acid, and 50 g of toluene were added to the above ester and the mixture was stirred at 150°C for 4 hours. Then, saturated sodium bicarbonate aqueous solution was added to stop the reaction, and ethyl acetate was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the acetal was purified by column chromatography to obtain the compound in good yield.

[0227] The above acetal compound was mixed with acetonitrile and water (1:1 by mass ratio) to make a 1 M solution, then 20.0 mmol of lithium hydroxide was added and the mixture was reacted at room temperature for 4 hours. After that, 1 M hydrochloric acid was added to acidify the system, and then methylene chloride was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the carboxylic acid compound was obtained in good yield.

[0228] 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 to the above carboxylic acid and reacted at room temperature for 5 hours. After dilution with water, methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (B-1) represented by the above formula (B-1) was obtained in good yield by purification by column chromatography.

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

[0230] [ka]

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

[0232] [ka]

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

[0234] The above diester was mixed with 20.0 mmol of 1-adamantane carbonyl chloride, 20.0 mmol of triethylamine, and 50 g of acetonitrile, and stirred at room temperature for 12 hours. Then, saturated ammonium chloride aqueous solution was added to stop the reaction, followed by extraction with ethyl acetate, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, 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] The above triester was mixed with acetonitrile and water (1:1 by mass ratio) to make a 1 M solution, then 15.0 mmol of lithium hydroxide was added and the mixture was reacted at room temperature for 1 hour. After that, 1 M hydrochloric acid was added to acidify the system, and then methylene chloride was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation to obtain the diester carboxylic acid compound in good yield.

[0236] 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 to the above diester carboxylic acid and reacted at room temperature for 5 hours. After dilution with water, methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (B-23) represented by the above formula (B-23) was obtained in good yield by column chromatography.

[0237] [Synthesis Examples 24-31] (Synthesis of compounds (B-24) to (B-31)) Compound (1), represented by the following formulas (B-24) to (B-31), was 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) (Hereafter, 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 resins and high-fluorine content resins> 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 refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0242] [ka]

[0243] [Synthesis Example 32] (Synthesis of resin (A-1)) Monomers (M-1), (M-2), and (M-13) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% of the total monomers used, 100 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone 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 while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdered resin (A-1) (yield: 83%). The Mw of resin (A-1) was 8,800, and the Mw / Mn ratio was 1.50. 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-2), and (M-13) was 41.3 mol%, 13.8 mol%, and 44.9 mol%, respectively.

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

[0245] [Table 1]

[0246] [Synthesis Example 43] (Synthesis of acid-generating resin (B-32)) Monomers (M-1), (M-2), (M-5), and (B-22) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 10 / 45 / 5 (mol%). AIBN (azobisisobutyronitrile) (6 mol% of the total monomers used, based on 100 mol%) was added as an initiator to prepare the monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C. The monomer solution was then added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dried at 50°C for 24 hours to obtain a white powdery resin (A-12) (yield: 72%). The Mw of the acid-generating resin (B-32) was 5,600, and the Mw / Mn ratio was 1.61. 13 1C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-2), (M-5), and (B-22) was 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 monomers of the types and proportions shown in Table 2 below were used. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained acid generating resins are also shown in Table 2 below.

[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) to a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol 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 while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the resin. The obtained solid was filtered off and dried at 50°C for 13 hours to obtain a 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 of each structural unit derived from (M-1) and (M-18) was 51.3 mol% and 48.7 mol%, respectively.

[0250] [Synthesis Examples 47-51] (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 monomers used were of the types and proportions shown in Table 3 below. The content percentage (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit 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 200 parts by mass of 2-butanone to a molar ratio of 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 200 parts by mass of 2-butanone 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 while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine content resin (E-1) was obtained (yield: 69%). The Mw of the high-fluorine-content resin (E-1) was 6,000, and the Mw / Mn ratio was 1.62. Furthermore, 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-20) was 19.9 mol% and 80.1 mol%, respectively.

[0253] [Synthesis Examples 53-56] (Synthesis of high-fluorine content resins (E-2) to high-fluorine content resins (E-5)) High-fluorine-content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 52, except that monomers of the types and proportions shown in Table 3 below were used. The content percentage (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine-content resins are 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 exposure] [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 [D] solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).]

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

[0260] [Table 5]

[0261] [Formation of resist pattern using positive radiation-sensitive resin composition for ArF exposure] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure positive-type radiation-sensitive resin composition prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography 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, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (40 nm line and space pattern).

[0262] <Rating> The sensitivity and LWR performance of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure were evaluated according to the following method. The results are shown in Table 6 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

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

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

[0265] [Table 6]

[0266] As is clear from the results in Table 6, the radiation-sensitive resin composition of the example showed good sensitivity and LWR performance when used in ArF exposure, whereas the comparative example exhibited inferior characteristics compared to the example. Therefore, when the radiation-sensitive resin composition of the example is used in ArF exposure, a resist pattern with high sensitivity and good LWR performance can be formed.

[0267] [Preparation of positive-type radiation-sensitive resin compositions for extreme ultraviolet (EUV) exposure] [Example 58] A radiation-sensitive resin composition (J-58) was prepared by mixing [A] 100 parts by mass of (A-12) as a resin, [B] 15.0 parts by mass of (B-7) as compound (1), [C] 4.0 parts by mass of (C-2) as an acid diffusion control agent, [E] 3.0 parts by mass of (E-5) as a high fluorine-content resin (solids), and [D] 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0268] [Examples 59-70 and Comparative Examples 16-19] 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 components used were of the types and in the amounts shown in Table 7 below.

[0269] [Table 7]

[0270] [Formation of Resist Pattern Using 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. On this anti-reflection film, the prepared positive radiation-sensitive resin composition for EUV lithography was applied using the spin coater, and PB was performed at 13°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 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. A scanning electron microscope (CG-5000 from Hitachi High-Technologies Corporation) was used for measuring the length of the resist pattern.

[0272] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure, the exposure amount for forming a 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 30 mJ / cm². 2 The following cases are considered "good" and 30 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0273] [LWR performance] The mask size was adjusted to form a 32nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line jaggedness and better performance. LWR performance was evaluated as "good" if it was 3.5nm or less, and "poor" if it was greater than 3.5nm.

[0274] [Table 8]

[0275] As is clear from the results in Table 8, the radiation-sensitive resin composition of the example showed good sensitivity and LWR performance when used in EUV exposure, whereas the comparative example exhibited inferior characteristics compared to the example.

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

[0277] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure negative-type radiation-sensitive resin composition (J-71) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography 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 exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0278] <Rating> The CDU performance of resist patterns formed using the above-mentioned ArF exposure negative-type radiation-sensitive resin composition was evaluated according to the following method. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[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 scanning electron microscope described above. The dimensional variation (3σ) was determined and defined as the CDU performance (nm). A smaller CDU value indicates less variation in hole diameter over long periods and therefore better performance.

[0280] As a result of evaluating the resist patterns using the above-mentioned ArF exposure negative-type radiation-sensitive resin composition, the radiation-sensitive resin composition of Example 71 showed good sensitivity and CDU performance even when a negative-type resist pattern was formed by ArF exposure.

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

[0282] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. On this base layer anti-reflective coating, the prepared negative-type radiation-sensitive resin composition for EUV exposure was applied using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

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

[0284] The radiation-sensitive resin composition and resist pattern formation method described above allow for the formation of resist patterns with good sensitivity to exposure light and excellent LWR and CDU performance. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. An onium salt compound represented by the following formula (1-2). 【Chemistry 1】 (In the above equation (1-2), R ｆ１ and R ｆ２ Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R １ This 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 Each of these is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n １ is an integer of 1 or 2. R ｆ１ and R ｆ２ When there are a plurality of each, the plurality of R ｆ１ and R ｆ２ are the same as or different from each other. n ２ R is an integer between 0 and 4. １ and R ２ If there are multiple instances of each, then multiple R １ and R ２ They are either identical or different from one another. However, n １ +n ２ The integer is between 2 and 6. X1 and X ２ Each of these is independently either an oxygen atom or a sulfur atom. Z+ is a monovalent, radiation-sensitive onium cation. R ８ｂ and R ９ｂ Each of these is independently either a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R ８ｂ and R ９ｂ These can be combined to form a ring structure with 3 to 20 members, along with the carbon atoms to which they bond. n ４ It is 1.

2. The above R ８ｂ and R ９ｂ The onium salt compound according to claim 1, wherein the organic group represented is independently a monovalent linear 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. The onium salt compound according to claim 2, wherein the above-mentioned 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 The onium salt compound according to any one of claims 1 to 3, wherein the ring structure, which is formed by combining these with the carbon atoms to which they are bonded, has 3 to 20 members and 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. The onium salt compound according to any one of claims 1 to 4, wherein the radiation-sensitive onium cation in formula (1-2) above is a sulfonium cation or an iodonium cation.

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

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

8. The above R ｆ１ and R ｆ２ Each of these is independently a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms. R １ and R ２ It 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.

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