Radiation-sensitive resin composition and method for forming resist pattern

Abstract

Provided are a radiation-sensitive resin composition in which sensitivity, CDU performance, and LWR performance can be exhibited at a sufficient level, and a method for forming a resist pattern. This radiation-sensitive resin composition comprises: an onium salt compound represented by formula (1); a resin including a structural unit having an acid-dissociable group; and a solvent. (In formula (1), R1 is a substituted or unsubstituted monovalent organic group having a cyclic structure or a chain hydrocarbon group having at least 2 carbon atoms. X is an oxygen atom, a sulfur atom, or -NRα-. Rα is a hydrogen atom or a monovalent hydrocarbon group having 1-10 carbon atoms. Z+ is a monovalent onium cation.)

Description

[Technical Field]

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

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

[0003] The photolithography technology mentioned above is promoting the miniaturization of patterns by using short-wavelength radiation such as ArF excimer lasers, and also by using liquid immersion lithography, in which exposure is performed with the space between the lens of the exposure device and the resist film filled with a liquid medium.

[0004] As efforts toward further technological advances continue, a technology has been proposed in which a photosensitive quencher is added to a resist composition to capture acid that has diffused to unexposed areas through an ion exchange reaction, thereby improving lithography performance using ArF exposure (Patent Document 1).In addition, lithography using shorter wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered as a next-generation technology. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-54833 Summary of the Invention [Problem to be solved by the invention]

[0006] In these efforts toward next-generation technologies, resist performance equivalent to or better than conventional performance is required in terms of critical dimension uniformity (CDU), which is an index of sensitivity and uniformity of line width and hole diameter, and line width roughness (LWR), which indicates variation in the line width of the resist pattern, etc. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

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

[0008] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] That is, in one embodiment, the present invention relates to a compound comprising an onium salt compound represented by the following formula (1) (hereinafter also referred to as "compound (1)"), a resin including a structural unit having an acid-dissociable group; Solvent and The present invention relates to a radiation-sensitive resin composition comprising: [ka] (In the above formula (1), R 1 is a substituted or unsubstituted monovalent organic group having a cyclic structure or a chain hydrocarbon group having two or more carbon atoms. X is an oxygen atom, a sulfur atom, or -NR α -R α is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Z + is a monovalent onium cation.

[0010] The radiation-sensitive resin composition contains compound (1) as a quencher (acid diffusion controller), enabling it to exhibit excellent sensitivity, CDU performance, and LWR performance during resist pattern formation. Without being bound by any theory, the reasons for this are presumed to be as follows. One possible explanation is that two electron-withdrawing fluorine atoms are bonded to the carbon atom adjacent to the carboxylate ion, and a similarly electron-withdrawing (thio)ether bond or nitrogen atom is located adjacent to that carbon atom, thereby causing compound (1) (the anion portion) to exhibit moderately weak basicity and promoting salt exchange with the generated acid. Another possible explanation is that the introduction of a cyclic structure or a chain hydrocarbon structure of a predetermined length into the anion portion of compound (1) also suppresses the diffusion length of compound (1) itself. These effects are presumed to improve compound (1)'s ability to control acid diffusion in unexposed areas, enabling it to exhibit excellent resist properties. The organic group refers to a group containing at least one carbon atom.

[0011] In another embodiment, the present invention provides a method for producing a resist film from the radiation-sensitive resin composition, a step of exposing the resist film to light; and The present invention also relates to a method for forming a resist pattern, which includes a step of developing the exposed resist film.

[0012] The method for forming a resist pattern uses the above-mentioned radiation-sensitive resin composition, which exhibits excellent sensitivity, CDU performance, and LWR performance, and therefore can efficiently form a high-quality resist pattern. DETAILED DESCRIPTION OF THE INVENTION

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

[0014] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "composition") contains compound (1), a resin, and a solvent. It may further contain a radiation-sensitive acid generator, if necessary. The composition may contain other optional components as long as they do not impair the effects of the present invention.

[0015] (Compound (1)) Compound (1) can function as a quencher (also called a "photodegradable base" or "acid diffusion controller") that captures acid in pre-exposed or unexposed areas. Compound (1) is represented by the following formula (1): [ka] (In the above formula (1), R 1 is a substituted or unsubstituted monovalent organic group having a cyclic structure or a chain hydrocarbon group having two or more carbon atoms. X is an oxygen atom, a sulfur atom, or -NR α -R α is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Z + is a monovalent onium cation.

[0016] By including the compound (1), the radiation-sensitive resin composition can be imparted with high levels of sensitivity, CDU performance, and LWR performance.

[0017] In the above formula (1), the substituted or unsubstituted monovalent organic group having a cyclic structure is not particularly limited, and may be either a group containing only a cyclic structure or a group combining a cyclic structure with a chain structure. The cyclic structure may be either a monocyclic or polycyclic structure. The cyclic structure may be an aromatic ring structure, an alicyclic structure, a heterocyclic structure, or a combination thereof. The heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. These structures are preferably included as the smallest basic skeleton of the cyclic structure. The number of cyclic structures as the basic skeleton in the organic group may be one or two or more. A heteroatom may be present between the carbon atoms forming the skeleton of the cyclic structure or the chain structure, and a hydrogen atom on a carbon atom of the cyclic structure or the chain structure may be substituted with another substituent. R 1 By having a cyclic structure, the affinity of compound (1) with a resin can be increased, and the diffusion length of compound (1) can be appropriately suppressed, thereby improving the resist performance of the radiation-sensitive resin composition.

[0018] Examples of the aromatic ring structure as the basic skeleton include benzene, indene, naphthalene, azulene, phenanthrene, anthracene, tetracene, tetraphene, chrysene, pyrene, pentacene, triphenylene, and fluorene.

[0019] In particular, the aromatic ring structure is preferably at least one selected from the group consisting of the following structures: [ka]

[0020] Examples of the alicyclic structure as the basic skeleton include: Single-ring cycloalkane structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, and cycloheptane; Polycyclic cycloalkane structures such as norbornane, adamantane, tricyclodecane, tetracyclododecane, and decahydronaphthalene; Single-ring cycloalkene structures such as cyclopropene, cyclobutene, cyclopentene, and cyclohexene; Examples include polycyclic cycloalkenyl structures such as norbornene, tricyclodecene, and tetracyclododecene.

[0021] Among these, the alicyclic structure is preferably at least one selected from the group consisting of the following structures: [ka]

[0022] The heterocyclic structure as the basic skeleton includes an aromatic heterocyclic structure and an alicyclic heterocyclic structure in which one or more heteroatoms are interposed between the carbon atoms forming the skeleton of the aromatic ring structure or the alicyclic structure. A five-membered aromatic structure that has aromaticity due to the introduction of a heteroatom is also included in the heterocyclic structure. Examples of heteroatoms include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0023] Examples of the aromatic heterocyclic structure include: Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; nitrogen atom-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms, such as thiazole, benzothiazole, thiazine, and oxazine.

[0024] Examples of the alicyclic heterocyclic structure include Oxygen atom-containing alicyclic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; Nitrogen atom-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thietane, thiolane, and thiane; Examples include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0025] Examples of the lactone structure, cyclic carbonate structure and sultone structure include structures represented by the following formulae (H-1) to (H-9).

[0026] [ka]

[0027] In the above formula, m is an integer of 1 to 3.

[0028] Among these, the heterocyclic structure is preferably at least one selected from the group consisting of the following structures: [ka]

[0029] When compound (1) has a plurality of the above-mentioned cyclic structures and these cyclic structures are connected by a chain structure, the chain structure is not particularly limited, but is preferably a single bond, -O-, -COO-, -OCO-, -CO-, an alkanediyl group, or a combination thereof. Examples of the alkanediyl group include alkanediyl groups having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a propanediyl group, and a butanediyl group. This allows the molecular design to be appropriately adjusted depending on the properties required of compound (1).

[0030] Examples of substituents substituting hydrogen atoms on carbon atoms of the cyclic structure or chain structure include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxy groups; carboxy groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups, as well as groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O). These substituents may contain a cyclic structure.

[0031] The substituted or unsubstituted monovalent organic group having a cyclic structure in the above formula (1) has one or a combination of the above cyclic structures, and if necessary, has a cyclic structure and the above chain structure in combination. The organic group may have multiple types of cyclic structures, or may have multiple cyclic structures of the same type. Similarly, the chain structure may have multiple types of chain structures, or may have multiple chain structures of the same type.

[0032] In the above formula (1), the chain hydrocarbon group having 2 or more carbon atoms is not particularly limited, and examples thereof include chain hydrocarbon groups having 2 to 20 carbon atoms. Examples of the chain hydrocarbon group having 2 to 20 carbon atoms include linear or branched saturated hydrocarbon groups having 2 to 20 carbon atoms, and linear or branched unsaturated hydrocarbon groups having 2 to 20 carbon atoms. The number of carbon atoms may be 2 or more, but the lower limit is preferably 3, more preferably 4, even more preferably 5, and particularly preferably 6. The upper limit of the number of carbon atoms is preferably 18, more preferably 16, even more preferably 14, and particularly preferably 12. The chain hydrocarbon group having 2 to 20 carbon atoms is preferably a chain saturated hydrocarbon group having 2 to 20 carbon atoms.

[0033] Some or all of the hydrogen atoms on the carbon atoms of the chain hydrocarbon group may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0034] The linear saturated hydrocarbon group having 2 to 20 carbon atoms is preferably at least one selected from the group consisting of the following structures: [ka] (In the formula, * represents a bond to another structure.)

[0035] The branched saturated hydrocarbon group having 2 to 20 carbon atoms is preferably at least one selected from the group consisting of the following structures: [ka] (In the formula, * represents a bond to another structure.)

[0036] The anion moiety in compound (1) may have any structure obtained by combining the above-mentioned cyclic structure and, if necessary, a chain structure, or the above-mentioned chain hydrocarbon group. Specific examples of the anion moiety are not particularly limited, but include, for example, structures represented by the following formulas:

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] Examples of the monovalent onium cation include radiolytic onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, such as sulfonium cation, tetrahydrothiophenium cation, iodonium cation, phosphonium cation, diazonium cation, and pyridinium cation. Among these, sulfonium cation or iodonium cation is preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] In the above formula (X-1), R a1 , R a2 and R a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -SR T or a ring structure formed by combining two or more of these groups. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R a1 ~R a3 and R P , R Q and R T If there are multiple R a1 ~R a3 and RP , R Q and R T may be the same or different.

[0048] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. n k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer between 0 and 7. R b1 If there are multiple, multiple R b1 may be the same or different, and multiple R b1 R may represent a ring structure formed by combining with each other. b2 L is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R b2 If there are multiple, multiple R b2 may be the same or different, and multiple R b2 may represent a ring structure formed by combining with each other, and q is an integer of 0 to 3. In the formula, S + The ring structure containing may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton.

[0049] 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, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0050] In the above formula (X-4), R g1is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. n k2 When is 0, k10 is an integer between 0 and 4, and n k2 When is 1, k10 is an integer between 0 and 7. R g1 If there are multiple, multiple R g1 may be the same or different, and multiple R g1 R may represent a ring structure formed by combining with each other. g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 If there are multiple R g2 and R g3 may be the same or different.

[0051] In the above formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, or a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 If there are multiple R d1 and R d2 may be the same or different.

[0052] In the above formula (X-6), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0053] Compound (1) is formed by combining any anion moiety containing the above-mentioned monovalent organic group or chain hydrocarbon group having a cyclic structure with the above-mentioned monovalent onium cation. Specific examples of compound (1) include those represented by the following formulae (1-1) to (1-52).

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] Among these, compounds (1) represented by the above formulas (1-1) to (1-39) are preferred.

[0058] The content of compound (1) in the radiation-sensitive resin composition according to this embodiment is preferably 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the resin described below. The upper limit of the content is more preferably 18 parts by mass, even more preferably 15 parts by mass, and particularly preferably 10 parts by mass. The lower limit of the content is more preferably 1 part by mass, even more preferably 2 parts by mass. The content of compound (1) is appropriately selected depending on the type of resin used, the exposure conditions, the desired sensitivity, and the type and content of the radiation-sensitive acid generator described below. This allows for excellent sensitivity, CDU performance, and LWR performance to be exhibited during resist pattern formation.

[0059] (Method for synthesizing compound (1)) Compound (1) can be typically synthesized according to the following scheme. [ka] (In the formula, R 1 and Z + is the same as in formula (1) above. γ is a monovalent hydrocarbon group. M is an alkali metal.

[0060] An alcohol having a structure corresponding to the monovalent organic group or chain hydrocarbon group having a cyclic structure in the anion moiety undergoes a nucleophilic substitution reaction with α-bromodifluorocarboxylate under basic conditions to generate an anion moiety precursor. The anion moiety precursor is then hydrolyzed with a metal hydroxide, and finally reacted with an onium cation chloride corresponding to the onium cation moiety to promote salt exchange, thereby synthesizing the target compound (1). Compounds (1) having other structures can also be synthesized by appropriately selecting precursors corresponding to the anion moiety and onium cation moiety.

[0061] (resin) The resin is an aggregate of polymers having a structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (I)") (hereinafter also referred to as "base resin"). The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and that dissociates under the action of an acid. The radiation-sensitive resin composition has excellent pattern formability because the resin contains the structural unit (I).

[0062] In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may also have structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0063] Structural Units The structural unit (I) is a structural unit containing an acid-dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0064] [ka]

[0065] In the above formula (2), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10L each independently represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. 1 represents a single bond or a divalent linking group. 1 When is a divalent linking group, the carbon atom bonded to the oxygen atom of -COO- in the above formula (2) is a tertiary carbon, or the structure on the terminal side of the side chain is -COO-.

[0066] Above R 7 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0067] Above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0068] Above R 8 ~R 10 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0069] Above R 8 ~R 10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0070] Above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples thereof include aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl groups; and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0071] Above R 8 As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0072] Above R 9 and R 10 The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula (I) together with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a fused alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that a fused alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0073] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Preferred polycyclic alicyclic hydrocarbon groups include bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1]heptane-2,2-diyl. 3,7]Decane-2,2-diyl group (adamantane-2,2-diyl group) and the like are preferred.

[0074] The above L 1 Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, * -R LA O-, * -R LB COO- etc. (* indicates the bond on the oxygen side). * -R LB In the case of groups other than COO-, the carbon atom bonded to the oxygen atom of -COO- in the above formula (2) is a tertiary carbon and does not have a hydrogen atom. This tertiary carbon is obtained when two bonds extend from the same carbon atom in the group, or when one of the bonds in the group has one or two further substituents bonded to the carbon atom. Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms such as fluorine atoms or chlorine atoms, cyano groups, etc.

[0075] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms.

[0076] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0077] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0078] the above * -R LA O-R LA Examples of the alkyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, and the above-mentioned alkenediyl group.* -R LB COO-R LB Examples of the arenediyl group include the above-mentioned alkanediyl group, cycloalkanediyl group, alkenediyl group, and arenediyl group. Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0079] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure. 1 is a single bond or * -R LA Preferably, R is O-. LA is preferably an alkanediyl group.

[0080] Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0081] [ka]

[0082] In the above formulas (3-1) to (3-6), R 7 ~R 10 and R LA has the same meaning as in the above formula (2). i and j each independently represent an integer of 1 to 4. n A is 0 or 1.

[0083] i and j are preferably 1. 8 ~R 10 is preferably a methyl group, an ethyl group or an isopropyl group.

[0084] Of these, the structural unit (I-1) is preferably the structural unit (I-1-1), the structural unit (I-1-2), the structural unit (I-1-4), or the structural unit (I-1-5). The structural unit (I-1-1) preferably has a cyclopentane structure. The structural unit (I-1-5) preferably has n A is preferably 0.

[0085] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0086] The lower limit of the content of the structural unit (I) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 30 mol%, based on all structural units constituting the base resin. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, even more preferably 75 mol%, and particularly preferably 70 mol%. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0087] [Structural unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further including the structural unit (II), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Furthermore, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0088] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10).

[0089] [ka]

[0090] In the above formula, R L1is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5 and may be combined together to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0091] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these together with the carbon atoms to which they are bonded include R 9 and R 10 Examples include divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula (I) together with the carbon atoms to which they are bonded, and which have 3 to 8 carbon atoms. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0092] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0093] Of these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0094] The lower limit of the content of the structural unit (II) is preferably 20 mol%, more preferably 25 mol%, and even more preferably 30 mol%, based on all structural units constituting the base resin. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of the structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0095] Other structural units The base resin optionally contains other structural units in addition to the structural units (I) and (II). Examples of the other structural units include structural units containing polar groups (excluding those corresponding to the structural unit (II)). By further containing a structural unit containing a polar group, the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0096] Examples of the structural unit having a polar group include structural units represented by the following formulas.

[0097] [ka]

[0098] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0099] When the base resin has the structural unit having the polar group, the lower limit of the content of the structural unit having the polar group, based on all structural units constituting the base resin, is preferably 5 mol%, more preferably 8 mol%, and even more preferably 10 mol%. The upper limit of the content is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By setting the content of the structural unit having a polar group within the above range, the lithography performance such as resolution of the radiation-sensitive resin composition can be further improved.

[0100] In addition to the structural unit having the polar group, the base resin optionally contains a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of these are collectively referred to as "structural unit (III)"). The structural unit (III) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This resin is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. In this case, the resin preferably contains structural unit (I) in addition to structural unit (III).

[0101] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-labile group, and then to obtain structural unit (III) by deprotection through hydrolysis. The structural unit that gives structural unit (III) upon hydrolysis is preferably represented by the following formula (4-1) or (4-2).

[0102] [ka]

[0103] In the above formulas (4-1) and (4-2), R 11 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 12The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0104] Above R 12 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0105] In the case of a resin for exposure to radiation having a wavelength of 50 nm or less, the lower limit of the content of the structural unit (III) is preferably 10 mol %, more preferably 20 mol %, based on the total structural units constituting the resin, and the upper limit of the content is preferably 70 mol %, more preferably 60 mol %.

[0106] (Method for synthesizing base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0107] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical initiators can be used alone or in combination of two or more.

[0108] Examples of the solvent used in the polymerization include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0109] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0110] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin as converted to polystyrene by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the base resin is below the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is above the upper limit, the developability of the resist film may be reduced.

[0111] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0112] The Mw and Mn of the resin in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0113] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0114] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0115] (other resins) The radiation-sensitive resin composition of this embodiment may contain, as an additional resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0116] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (IV)"), and may also have the structural unit (I) or structural unit (II) of the above base resin, as necessary.

[0117] [ka]

[0118] In the above formula (5), R 13is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0119] Above R 13 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (IV), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0120] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (IV), a single bond and -COO- are preferred, and -COO- is more preferred.

[0121] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0122] Above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0123] Above R 14 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0124] When the high-fluorine-content resin has the structural unit (IV), the lower limit of the content of the structural unit (IV) is preferably 30 mol%, more preferably 35 mol%, even more preferably 40 mol%, and particularly preferably 45 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of this content is preferably 90 mol%, more preferably 85 mol%, and even more preferably 80 mol%. By setting the content of the structural unit (IV) within this range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0125] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (V)) in addition to or instead of the structural unit (IV): By having the structural unit (f-2), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0126] [ka]

[0127] The structural unit (V) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0128] When the structural unit (V) has an alkali-soluble group (x), R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (V) has an alkali-soluble group (x), it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (V) having an alkali-soluble group (x), A 1 is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0129] When the structural unit (V) has an alkali-dissociable group (y), R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1 or RF is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (V) has an alkali-dissociable group (y), the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (V) having an alkali-dissociable group (y), A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0130] R C As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0131] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0132] When the high-fluorine-content resin has the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 40 mol%, more preferably 50 mol%, and even more preferably 60 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of the structural unit (V) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0133] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0134] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.7.

[0135] The lower limit of the content of the high-fluorine-content resin is preferably 0.1 mass%, more preferably 0.5 mass%, further preferably 1 mass%, and even more preferably 1.5 mass%, based on the total solid content in the radiation-sensitive resin composition, and the upper limit of the content is preferably 20 mass%, more preferably 15 mass%, further preferably 10 mass%, and particularly preferably 7 mass%.

[0136] The lower limit of the content of the high-fluorine content resin is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 1.5 parts by mass, relative to 100 parts by mass of the base resin, and the upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, even more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0137] By setting the content of the high-fluorine-containing resin within the above range, the high-fluorine-containing resin can be more effectively distributed unevenly on the surface layer of the resist film, thereby further improving the water repellency of the surface of the resist film during immersion lithography. The radiation-sensitive resin composition may contain one or more high-fluorine-containing resins.

[0138] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0139] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of this embodiment preferably further contains a radiation-sensitive acid generator that generates, upon exposure, an acid with a lower pKa than the acid generated from compound (1), i.e., a relatively strong acid. When the resin contains structural unit (I) having an acid-dissociable group, the acid generated from the radiation-sensitive acid generator upon exposure can dissociate the acid-dissociable group of the structural unit (I) to generate a carboxyl group or the like. This function differs from the function of compound (1), which, under pattern-forming conditions using the radiation-sensitive resin composition, does not substantially dissociate the acid-dissociable group of the structural unit (I) or the like of the resin, thereby suppressing the diffusion of the acid generated from the radiation-sensitive acid generator in unexposed areas. The difference between the functions of compound (1) and the radiation-sensitive acid generator is determined by the energy required to dissociate the acid-dissociable group of the structural unit (I) or the like of the resin, the thermal energy conditions applied when forming a pattern using the radiation-sensitive resin composition, and other factors. The radiation-sensitive acid generator may be contained in the radiation-sensitive resin composition in a form in which it exists as a compound alone (isolated from the polymer), in which it is incorporated as part of the polymer, or in both of these forms. However, the form in which it exists as a compound alone is preferred.

[0140] When the radiation-sensitive resin composition contains the radiation-sensitive acid generator, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of development with an aqueous alkaline solution, while becoming poorly soluble in the developer in the case of development with an organic solvent.

[0141] Examples of the radiation-sensitive acid generator include onium salt compounds (excluding compound (1)), sulfonimide compounds, halogen-containing compounds, and diazoketone compounds. Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts. Of these, sulfonium salts and iodonium salts are preferred.

[0142] Examples of acids that are generated upon exposure include those that generate sulfonic acids upon exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfo group. Among these, those having a cyclic structure are particularly preferred as radiation-sensitive acid generators.

[0143] These radiation-sensitive acid generators may be used alone or in combination of two or more. The lower limit of the amount of the radiation-sensitive acid generator is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 5 parts by mass. The upper limit of the amount is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 20 parts by mass. This allows the resist pattern to exhibit excellent sensitivity, CDU performance, and LWR performance during formation.

[0144] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least Compound (1) and the resin, as well as the radiation-sensitive acid generator and other components that may be optionally contained therein.

[0145] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0146] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples of suitable polyhydric alcohol solvents include partially etherified polyhydric alcohol solvents in which some of the hydroxy groups of the above polyhydric alcohol solvents have been etherified.

[0147] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples of the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

[0148] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0149] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0150] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of the solvent include polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0151] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0152] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0153] (Other optional ingredients) The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0154] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which, in the baking step after the floodwise exposure step, (1) induces a crosslinking reaction in the polymer component by an acid-catalyzed reaction, (2) increases the molecular weight of the polymer component, and (3) reduces the solubility of the patternwise exposed area in a developer. Examples of the functional group include a (meth)acryloyl group, a hydroxymethyl group, an alkoxymethyl group, an epoxy group, and a vinyl ether group.

[0155] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds having a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0156] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0157] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, and vinylene carbonate.

[0158] The nitrile compound may, for example, be succinonitrile.

[0159] The polyhydric alcohol may, for example, be glycerin.

[0160] The lower limit of the content of the uneven distribution accelerator is preferably 10 parts by mass, more preferably 15 parts by mass, even more preferably 20 parts by mass, and even more preferably 25 parts by mass, relative to 100 parts by mass of the total amount of resin in the radiation-sensitive resin composition. The upper limit of the content is preferably 300 parts by mass, more preferably 200 parts by mass, even more preferably 100 parts by mass, and particularly preferably 80 parts by mass. The radiation-sensitive resin composition may contain one or more uneven distribution accelerators.

[0161] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.) The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0162] (alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

[0163] Examples of the alicyclic skeleton-containing compound include: Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0164] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0165] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0166] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing compound (1), a resin, a radiation-sensitive acid generator, and optionally a high-fluorine-content resin, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter with a pore size of about 0.05 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0167] <Method for forming a resist pattern> A method for forming a resist pattern according to one embodiment of the present invention includes: a step (1) of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition onto a substrate (hereinafter also referred to as a "resist film forming step"); A step (2) of exposing the resist film to light (hereinafter also referred to as the "exposure step"); and The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0168] According to the above-described resist pattern forming method, a high-quality resist pattern can be formed because the above-described radiation-sensitive resin composition is used, which exhibits excellent sensitivity, depth of focus, and process margin in the exposure step. Each step will now be described.

[0169] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, and preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0170] When performing immersion exposure, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0171] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (I) and (III) as the base resin in the composition.

[0172] [Exposure process] In this step (step (2) above), the resist film formed in step (1), the resist film formation step, is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). The radiation used for exposure may be, depending on the line width of the desired pattern, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), X-rays, and gamma rays; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0173] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser (wavelength 193 nm), water is preferred for its availability and ease of handling, in addition to the above considerations. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0174] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the resin or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0175] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0176] In the case of alkaline development, the developer used for the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0177] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing organic solvents. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As the ketone solvent, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0178] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which developer is sprayed onto the surface of the substrate (spray method), and a method in which developer is continuously dispensed by scanning a developer dispensing nozzle at a constant speed over a substrate that is rotating at a constant speed (dynamic dispense method). [Example]

[0179] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0180] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above, and the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0181] [ 13 C-NMR analysis] polymer 13 C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0182] <Synthesis of resin and high fluorine content resin> The monomers used in the synthesis of each resin and high-fluorine content resin in each Example and Comparative Example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is taken as 100 mol %.

[0183] [ka]

[0184] [Synthesis Example 1] (Synthesis of Resin (A-1)) Monomer (M-1), monomer (M-2), and monomer (M-10) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% relative to the total of 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered, and dried at 50°C for 24 hours to obtain polymer (A-1) as a white powder (yield: 80%). The Mw of polymer (A-1) was 8,700, and the Mw / Mn was 1.49. Furthermore, as a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2), and (M-10) were 39.9 mol%, 14.3 mol%, and 45.8 mol%, respectively.

[0185] [Synthesis Examples 2 to 11] (Synthesis of Resin (A-2) to Resin (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. The content (mol %) of each structural unit, the yield (%), and physical properties (Mw and Mw / Mn) of the resulting resins are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0186] [Table 1]

[0187] [Synthesis Example 12] (Synthesis of Resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) at a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the mixture was stirred at 70°C for 6 hours to carry out a hydrolysis reaction. After the reaction was completed, the remaining solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the resin. The resulting solid was filtered and dried at 50°C for 13 hours to obtain white powdery resin (A-12) (yield: 79%). The Mw of resin (A-12) was 5200, and the Mw / Mn ratio was 1.60. Furthermore, 13C-NMR analysis revealed that the content ratios of structural units derived from (M-1) and (M-18) were 51.3 mol% and 48.7 mol%, respectively.

[0188] [Synthesis Examples 13 to 15] (Synthesis of Resin (A-13) to Resin (A-15)) Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the types and blending ratios of monomers shown in Table 2 were used. The content (mol %) of each structural unit, the yield (%), and the physical properties (Mw and Mw / Mn) of the resulting resins are also shown in Table 2.

[0189] [Table 2]

[0190] [Synthesis Example 16] (Synthesis of high fluorine content resin (E-1)) Monomer (M-1) and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was added to a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerized solution was cooled to below 30°C with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of high-fluorine-content resin (E-1) (yield: 69%). The high fluorine content resin (E-1) had an Mw of 6,000 and an Mw / Mn ratio of 1.62. Furthermore, as a result of C-NMR analysis, the contents of the structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.

[0191] [Synthesis Examples 17-20] (Synthesis of High Fluorine Content Resin (E-2) to High Fluorine Content Resin (E-5)) High fluorine content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 16, except for using monomers of the types and blending ratios shown in Table 3 below. The content (mol %) of each structural unit, yield (%) and physical properties (Mw and Mw / Mn) of the obtained high fluorine content resins are also shown in Table 3 below.

[0192] [Table 3]

[0193] <Synthesis of Compound (1)> [Synthesis Example 21] (Synthesis of Compound (C-1)) A reaction vessel was charged with 20.0 mmol of phenol, 30.0 mmol of bromodifluoroethyl acetate, 30.0 mmol of 1,8-diazabicyclo[5,4,0]-7-undecene, and 50 g of dimethylformamide, and the mixture was stirred at 50°C for 4 hours. The reaction solution was then cooled to below 30°C, diluted with water, and extracted with ethyl acetate. The organic layer was separated. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the mixture was purified by column chromatography to obtain the phenol derivative in good yield.

[0194] A mixture of methanol and water (1:1 (mass ratio)) was added to the above phenol derivative to prepare a 1M solution, and then 20.0 mmol of sodium hydroxide was added and the mixture was allowed to react at 50°C for 2 hours. Extraction with acetonitrile and distillation of the solvent yielded a sodium salt derivative. 20.0 mmol of triphenylsulfonium chloride was added to the above sodium salt derivative, and a mixture of water and dichloromethane (1:3 (mass ratio)) was added. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The resulting organic layer was dried over sodium sulfate, and the solvent was distilled off to obtain compound (C-1) represented by the following formula (C-1) in good yield. The synthesis scheme for compound (C-1) is shown below.

[0195] [ka]

[0196] [Synthesis Examples 22 to 59] (Synthesis of Compounds (C-2) to (C-39)) Compounds (1) represented by the following formulae (C-2) to (C-39) were synthesized in the same manner as in Synthesis Example 21, except that the raw materials and precursors were changed as appropriate.

[0197] [ka]

[0198] [ka]

[0199] <Preparation of Radiation-Sensitive Resin Composition> The components other than the resin, high-fluorine-containing resin, and compound (1) used in the preparation of each radiation-sensitive resin composition are shown below.

[0200] [Radiation-sensitive acid generator] B-1 to B-8: Compounds represented by the following formulas (B-1) to (B-8) (hereinafter, the compounds represented by formulas (B-1) to (B-8) may be referred to as "radiation-sensitive acid generator (B-1)" to "radiation-sensitive acid generator (B-8)", respectively.)

[0201] [ka]

[0202] [Acid diffusion controllers other than compounds (C-1) to (C-20)] cc-1 to cc-10: Compounds represented by the following formulas (cc-1) to (cc-10) (hereinafter, the compounds represented by formulas (cc-1) to (cc-10) may be referred to as "compound (cc-1)" to "compound (cc-10)", respectively.)

[0203] [ka]

[0204] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-butyrolactone D-4: Ethyl lactate

[0205] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] 100 parts by mass of (A-1) as a resin, 14.0 parts by mass of (B-4) as a radiation-sensitive acid generator, 2.3 parts by mass of (C-1) as a compound (acid diffusion controller), 5.0 parts by mass (solid content) of (E-1) as a high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) = 70 / 29 / 1 (mass ratio) as a 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).

[0206] [Examples 2 to 48 and Comparative Examples 1 to 10] Except for using each component of the types and contents shown in Table 4 below, radiation-sensitive resin compositions (J-2) to (J-48) and (CJ-1) to (CJ-10) were prepared in the same manner as in Example 1.

[0207]

Table 4

[0208] <Formation of a resist pattern using a positive-type ArF-exposure radiation-sensitive resin composition> A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The positive radiation-sensitive resin composition for ArF exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by pre-baking at 90°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a mask pattern with 40 nm spacing and 105 nm pitch. After exposure, PEB (post-exposure bake) was performed at 90°C for 60 seconds. The resist film was then alkaline-developed using a 2.38% by mass aqueous solution of TMAH as the alkaline developer, and after development, the resist film was washed with water and dried to form a positive resist pattern (40 nm line and space pattern). A positive resist pattern (40 nm hole, 105 nm pitch) was also formed in the same manner as above, except for changing the mask pattern.

[0209] <Evaluation> The resist patterns formed using the positive radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity, LWR performance, and CDU performance according to the following methods. The results are shown in Table 5. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0210] [sensitivity] In forming a resist pattern using the positive radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 23 mJ / cm 2The following are considered "good" and 23mJ / cm 2 If it exceeded this, it was rated as "poor".

[0211] [CDU performance] A total of 1,800 measurements were taken of a resist pattern with 40 nm holes and a 105 nm pitch using the above-mentioned scanning electron microscope at random points from the top of the pattern. The dimensional variation (3σ) was calculated and used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better performance. CDU performance was evaluated as "good" when it was 3.3 nm or less, and "poor" when it exceeded 3.3 nm.

[0212] [LWR performance] A resist pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 40 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 3.6 nm or less, and "poor" when it exceeded 3.6 nm.

[0213] [Table 5]

[0214] As is clear from the results in Table 5, when the radiation-sensitive resin compositions of the Examples were used for ArF exposure, the sensitivity, LWR performance, and CDU performance were good, whereas in the Comparative Examples, each property was inferior to that of the Examples. Therefore, when the radiation-sensitive resin compositions of the Examples were used for ArF exposure, resist patterns with high sensitivity and good LWR performance and CDU performance could be formed.

[0215] [Preparation of Positive-Working Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 49] 100 parts by mass of (A-12) as a resin, 20.0 parts by mass of (B-4) as a radiation-sensitive acid generator, 3.2 parts by mass of (C-1) as a compound (acid diffusion controller), 3.0 parts by mass of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) = 70 / 30 (mass ratio) as a 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-49).

[0216] [Examples 50 to 85 and Comparative Examples 11 to 14] Radiation-sensitive resin compositions (J-50) to (J-85) and (CJ-11) to (CJ-14) were prepared in the same manner as in Example 41, except that each component of the type and content shown in Table 6 below was used.

[0217]

Table 6

[0218] <Formation of resist pattern using positive-type radiation-sensitive resin composition for EUV lithography> A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The positive radiation-sensitive resin composition for EUV exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and then dried to form a positive resist pattern (32 nm line and space pattern).

[0219] <Evaluation> The sensitivity and LWR performance of the resist patterns formed using the above-mentioned positive radiation-sensitive resin composition for EUV exposure were evaluated according to the following methods. The results are shown in Table 7. The resist patterns were measured using a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation).

[0220] [sensitivity] In forming a resist pattern using the positive-tone radiation-sensitive resin composition for EUV exposure, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 30 mJ / cm 2 The following are considered "good" and 30mJ / cm 2 If it exceeded this, it was rated as "poor".

[0221] [LWR performance] A resist pattern was formed by irradiating the substrate with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 32 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR performance was evaluated as "good" when it was 4.0 nm or less, and "poor" when it exceeded 4.0 nm.

[0222] [Table 7]

[0223] As is clear from the results in Table 7, the radiation-sensitive resin compositions of the Examples had good sensitivity and LWR performance when used for EUV exposure, whereas the Comparative Examples were inferior in each property to the Examples.

[0224] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 86] A radiation-sensitive resin composition (J-86) was prepared by mixing 100 parts by mass of (A-6) as a resin, 16.0 parts by mass of (B-4) as a radiation-sensitive acid generator, 3.0 parts by mass of (C-1) as compound (1) (acid diffusion controller), 3.0 parts by mass (solids content) of (E-3) as a high-fluorine-content resin, and 3,230 parts by mass of a mixed solvent with a mass ratio of (D-1) / (D-2) / (D-3)=70 / 29 / 1, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0225] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for ArF exposure (J-86) prepared above was then coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 90°C for 60 seconds. The coating was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a 40 nm space, 105 nm pitch mask pattern. After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 90° C. Then, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm line and space pattern).

[0226] The resist pattern formed using the negative-tone radiation-sensitive resin composition for ArF exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 86 exhibited good sensitivity, LWR performance, and CDU performance even when a negative-tone resist pattern was formed by ArF exposure.

[0227] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 87] A radiation-sensitive resin composition (J-87) was prepared by mixing 100 parts by mass of (A-12) as the resin [A], 15.0 parts by mass of (B-4) as the radiation-sensitive acid generator [B], 5.0 parts by mass of (C-28) as the acid diffusion controller [C], 3.0 parts by mass (solids content) of (E-5) as the high fluorine content resin [E], and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0228] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for EUV exposure (J-87) prepared above was then coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0229] The resist pattern formed using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 87 had good sensitivity and CDU performance, even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0230] The radiation-sensitive resin composition and the method for forming a resist pattern described above can form a resist pattern that has good sensitivity to exposure light and excellent LWR and CDU performance, and therefore can be suitably used in the fabrication processes of semiconductor devices, which are expected to become increasingly miniaturized in the future.

Claims

1. an onium salt compound represented by the following formula (1); a resin including a structural unit having an acid-dissociable group; a radiation-sensitive acid generator that generates an acid having a pKa lower than that of an acid generated from the onium salt compound; Solvent and A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In the above formula (1), R １ is a monovalent group having only a cyclic structure, which is unsubstituted or in which hydrogen atoms on carbon atoms are substituted with substituents, or a chain hydrocarbon group having two or more carbon atoms, the cyclic structure is at least one selected from the group consisting of an aromatic ring structure and a heterocyclic structure, the aromatic ring structure is selected from the group consisting of the following structures, and the substituent is a halogen atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or a group in which a hydrogen atom of any of these groups is substituted with a halogen atom; or an oxo group (═O), The hydrogen atoms on the carbon atoms of the chain hydrocarbon group having two or more carbon atoms are either unsubstituted or substituted with halogen atoms. X is an oxygen atom, a sulfur atom, or —NR α - is. R α is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Z ＋ is a monovalent onium cation. 【Chemistry 2】

2. 2. The radiation-sensitive resin composition according to claim 1, wherein the heterocyclic structure is at least one selected from the group consisting of the following structures: 【Transformation 3】

3. 3. The radiation-sensitive resin composition according to claim 1, wherein the onium cation in the formula (1) is a sulfonium cation or an iodonium cation.

4. 4. The radiation-sensitive resin composition according to claim 1, wherein the content of the onium salt compound is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the resin.

5. 5. The radiation-sensitive resin composition according to claim 1, wherein the content of the radiation-sensitive acid generator is 0.1 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the resin.

6. A step of forming a resist film from the radiation-sensitive resin composition according to any one of claims 1 to 5; a step of exposing the resist film to light; and A method for forming a resist pattern, comprising the step of developing the exposed resist film.

7. 7. The method for forming a resist pattern according to claim 6, wherein the exposure is carried out using ArF excimer laser light, extreme ultraviolet light or electron beams.

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