Onium salt compound

Abstract

To provide a radiation-sensitive resin composition capable of exhibiting sensitivity, LWR performance and CDU performance at a sufficient level, a pattern forming method and an onium salt compound.SOLUTION: A radiation-sensitive resin composition includes an onium salt compound represented by formula (1), a resin including a structural unit having an acid-dissociable group, and a solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition, a pattern forming method, and an onium salt compound. [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 quencher (acid diffusion controller) is added to a resist composition to capture acid that has diffused to unexposed areas through a salt exchange reaction, thereby improving lithography performance with 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] Patent No. 5525968 Summary of the Invention [Problem to be solved by the invention]

[0006] Even as efforts toward these next-generation technologies are underway, resist performance that is equal to or better than conventional performance is required in terms of sensitivity, line width roughness (LWR) performance, which indicates variation in the line width of the resist pattern, and critical dimension uniformity (CDU) performance, which is an index of the uniformity of line width and hole diameter.

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

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

[0009] That is, in one embodiment, the present invention provides a compound comprising an onium salt compound represented by the following formula (1) (hereinafter also referred to as "onium salt 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 monovalent hydrocarbon group having 1 to 20 carbon atoms. 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R 2 and R 3 and represent a cyclic structure having 3 to 20 ring members formed by combining them together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and L 1 is a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms, or R 4 and L 1represents a group containing a heterocyclic structure having 3 to 20 ring members formed by combining together with the nitrogen atom to which they are bonded. L 2 represents a single bond or a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms. R f1 and R f2 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. f1 and R f2 If there are multiple R f1 and R f2 are the same or different from each other. n is an integer of 1 to 4. Z + is a monovalent radiation-sensitive onium cation.

[0010] The radiation-sensitive resin composition exhibits excellent sensitivity, LWR performance, and CDU performance during resist pattern formation. While not bound by any theory, the reason for this is presumed to be as follows: In the radiation-sensitive composition, onium salt compound (1) is presumed to function as a quencher (acid diffusion controller). In the exposed areas, acid generated from onium salt compound (1) or other radiation-sensitive acid generators, etc., upon exposure deprotects the tertiary alkoxycarbonyl group protecting the nitrogen atom in the onium salt compound (1) molecule, forming an intramolecular salt in which a sulfonate anion and an ammonium cation coexist, resulting in a dissolved state. Since onium salt compound (1) in the form of an intramolecular salt no longer functions as a quencher, it no longer captures the acid generated in the exposed areas, thereby improving the sensitivity of the radiation-sensitive resin composition. Meanwhile, in the unexposed areas, the protected nitrogen atom maintains an appropriate level of basicity, allowing the composition to exhibit its acid-capturing function. In this way, the increased sensitivity due to the loss of quencher function in the exposed areas, combined with the quencher function in the unexposed areas, enhances the contrast between the exposed and unexposed areas, and is presumed to be the reason for the various resist properties described above. In addition, the increased solubility in the developer in the exposed areas also suppresses the generation of residues, which is presumed to also contribute to the improvement in contrast.

[0011] In another embodiment, the present invention provides a resist film production method, comprising: exposing the resist film to light; developing the exposed resist film with a developer; The present invention relates to a pattern forming method comprising the steps of:

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

[0013] In still another embodiment, the present invention relates to an onium salt compound represented by the following formula (1) (ie, onium salt compound (1)). [ka] (In the above formula (1), R 1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R 2 and R 3 and represent a cyclic structure having 3 to 20 ring members formed by combining them together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and L 1 is a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms, or R 4 and L 1 represents a group containing a heterocyclic structure having 3 to 20 ring members formed by combining together with the nitrogen atom to which they are bonded. L 2 represents a single bond or a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms. R f1 and R f2are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. f1 and R f2 If there are multiple R f1 and R f2 are the same or different from each other. n is an integer of 1 to 4. Z + is a monovalent radiation-sensitive onium cation.

[0014] The onium salt compound (1) can eliminate quencher function in exposed areas of a resist film and exhibit appropriate basicity in unexposed areas. Therefore, when incorporated into a radiation-sensitive resin composition, the compound can impart excellent sensitivity, LWR performance, and CDU performance to the composition during resist pattern formation. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0016] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as the "composition") contains a specific onium salt 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. By including the specific onium salt compound (1), the radiation-sensitive resin composition can be endowed with high levels of sensitivity, LWR performance, and CDU performance.

[0017] (Onium salt compound (1)) The onium salt compound (1) can function as a quencher (also called a "photodegradable base" or "acid diffusion controller") that captures acid in the unexposed or unexposed areas. The onium salt compound (1) is represented by the above formula (1).

[0018] In the above formula (1), R 1 , R 2 , R 3 and R 4 The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is not particularly limited, and examples thereof include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

[0019] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0020] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups include bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. Preferred monocyclic unsaturated hydrocarbon groups include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. Preferred polycyclic unsaturated hydrocarbon groups include polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0021] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0022] R 2 and R 3Examples of the cyclic structure having 3 to 20 carbon atoms formed by combining these together with the carbon atoms to which they are bonded include structures in which one hydrogen atom has been further removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0023] Among them, R 1 , R 2 and R 3 are preferably each independently a chain hydrocarbon group having 1 to 5 carbon atoms, from the viewpoint of the structural stability of the tertiary alkoxycarbonyl group.

[0024] In the above formula (1), L 1 and L 2 Examples of the substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 40 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, one group selected from -CO-, -O-, -NH-, -S- and a cyclic acetal structure, or a group formed by combining two or more of these groups.

[0025] Examples of the divalent linear or branched hydrocarbon group having 1 to 40 carbon atoms include a methanediyl group, an ethanediyl group, a propanediyl group, a butanediyl group, a hexanediyl group, an octanediyl group, etc. Among these, an alkanediyl group having 1 to 8 carbon atoms is preferred.

[0026] Examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group, and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. Of these, cycloalkanediyl groups having 5 to 12 carbon atoms are preferred.

[0027] L 1 and L 2Examples of the substituent that substitutes some or all of the hydrogen atoms of include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.

[0028] R 4 and L 1 Examples of groups containing a heterocyclic structure having 3 to 20 ring members, which are formed by combining and bonding together with the nitrogen atom to which they are bonded (hereinafter also referred to as "heterocyclic structure-containing linking group") include groups containing aromatic heterocyclic structures and groups containing aliphatic heterocyclic structures. Five-membered aromatic structures that have aromaticity due to the introduction of heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0029] 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.

[0030] Examples of the aliphatic 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; Alicyclic heterocyclic structures containing multiple heteroatoms, such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane; Lactone structures, cyclic carbonate structures, cyclic acetal structures and sultone structures; Examples of such heterocyclic structures include a spiro heterocyclic structure in which a plurality of the above-mentioned heterocyclic structures are bonded to each other by sharing a quaternary carbon atom.

[0031] The heterocyclic structure-containing linking group includes not only a heterocyclic structure containing a nitrogen atom, but also a heterocyclic structure containing a nitrogen atom, a heterocyclic structure containing a hetero atom other than a nitrogen atom, and L 1 It is also possible to suitably employ a combination with at least one of the divalent linking groups shown below. As the heterocyclic structure containing a nitrogen atom, a pyrrolidine structure or a piperidine structure is preferred.

[0032] From the viewpoint of ease of intramolecular salt formation, L 2 is preferably a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 10 carbon atoms.

[0033] In the above formula (1), R f1 and R f2 As the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R 1 Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown below, structures having 1 to 10 carbon atoms can be suitably employed.

[0034] In the above formula (1), R f1 and R f2 Examples of the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms.

[0035] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms include fluorinated alkyl groups such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a heptafluoro-n-propyl group, a heptafluoro-i-propyl group, a nonafluoro-n-butyl group, a nonafluoro-i-butyl group, a nonafluoro-t-butyl group, a 2,2,3,3,4,4,5,5-octafluoro-n-pentyl group, a tridecafluoro-n-hexyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group; fluorinated alkenyl groups such as a trifluoroethenyl group and a pentafluoropropenyl group; Examples include fluorinated alkynyl groups such as a fluoroethynyl group and a trifluoropropynyl group.

[0036] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms include fluorinated cycloalkyl groups such as a fluorocyclopentyl group, a difluorocyclopentyl group, a nonafluorocyclopentyl group, a fluorocyclohexyl group, a difluorocyclohexyl group, an undecafluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, and a fluorotricyclodecyl group; Examples include fluorinated cycloalkenyl groups such as a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0037] The fluorinated hydrocarbon group is preferably the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms, more preferably a monovalent fluorinated alkyl group having 1 to 10 carbon atoms, still more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, and particularly preferably a linear perfluoroalkyl group having 1 to 6 carbon atoms.

[0038] n is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0039] The anion moiety of the onium salt compound (1) represented by the above formula (1) is not particularly limited, but examples thereof include structures represented by the following formulae (1a) to (1z).

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] In the above formula, Z + is the same as the above formula (1).

[0044] In the above formula (1), the above Z + Examples of the monovalent radiation-sensitive onium cation represented by the formula (X-1) include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, such as sulfonium cation, tetrahydrothiophenium cation, iodonium cation, phosphonium cation, diazonium cation, and pyridinium cation. Among these, sulfonium cation or iodonium cation is preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0045] [ka]

[0046] In the above formula (X-1), R a1 , R a2 and R a3are 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 R P , R Q and R T may be the same or different.

[0047] 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 b1R 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.

[0048] 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.

[0049] In the above formula (X-4), R g1 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 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 g3are 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.

[0050] 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.

[0051] 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.

[0052] The onium salt compound (1) is formed by any combination of the anion moiety defined by the above formula (1) and the above monovalent radiation-sensitive onium cation. Specific examples of the onium salt compound (1) include, but are not limited to, structures represented by the following formulae (1-1) to (1-26).

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] Among these, the onium salt compounds (1) represented by the above formulas (1-1) to (1-24) are preferred.

[0057] The content of the onium salt compound (1) in the radiation-sensitive resin composition according to this embodiment (the total content when multiple onium salt compounds are used in combination) is more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the resin described below. The content is more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. The content of the onium salt compound (1) is selected appropriately 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, LWR performance, and CDU performance to be exhibited during resist pattern formation.

[0058] (Method for synthesizing onium salt compound (1)) As the onium salt compound (1), R 4 and L 1As shown in the following scheme, the target onium salt compound (1) can be synthesized by reacting a halogenated alcohol with a protected piperidine carboxylic acid to form an ester, which is then reacted with a dithionite and an oxidizing agent to form a sulfonate, and finally reacting with an onium cation halide corresponding to the onium cation moiety to cause salt exchange.

[0059] [ka] (In the formula, R 1 , R 2 , R 3 , L 2 , R f1 , R f2 and Z + and n has the same meaning as in the above formula (1). h1 and X h2 is a halogen atom.)

[0060] Onium salt compounds (1) having other structures can also be synthesized by appropriately selecting a halogenated alcohol compound or a carboxylic acid compound with a protected nitrogen atom, which serves as the base for the anion moiety, and a precursor corresponding to the onium cation moiety.

[0061] (Other acid diffusion control agents) The radiation-sensitive resin composition may contain other acid diffusion controllers as long as the effects of the present invention are not impaired. Examples of other acid diffusion controllers include onium salt compounds other than the onium salt compound (1) that generate relatively weaker acids than the radiation-sensitive acid generators described below. Specific examples include compounds represented by the following formula:

[0062] [ka]

[0063] Other acid diffusion controllers include nitrogen-containing compounds other than the onium salt compound (1), such as amine compounds, diamine compounds, polyamine compounds, amide group-containing compounds, urea compounds, and nitrogen-containing heterocyclic compounds. These nitrogen-containing compounds may be compounds having a tertiary alkoxycarbonyl group protecting a nitrogen atom. These acid diffusion controllers may be used alone or in combination of two or more.

[0064] (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).

[0065] 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.

[0066] Structural Units The structural unit (I) is a structural unit containing an acid-dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0067] [ka]

[0068] In the above formula (3), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Above R 8 ~R 10Examples 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.

[0073] 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.

[0074] 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.

[0075] 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).

[0076] 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.

[0077] 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.

[0078] 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)").

[0079] [ka]

[0080] In the above formulas (3-1) to (3-6), R 7 ~R 10 has the same meaning as in the above formula (3). i and j each independently represent an integer of 1 to 4. k and l are 0 or 1.

[0081] i and j are preferably 1. 8 R is preferably a methyl group, an ethyl group, or an isopropyl group. 9 and R 10 As the alkyl group, a methyl group or an ethyl group is preferred.

[0082] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0083] The content of the structural unit (I) (the total content when multiple types are included) relative to all structural units constituting the base resin is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0084] [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.

[0085] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10).

[0086] [ka]

[0087] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4and 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.

[0088] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded include R 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.

[0089] 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-.

[0090] 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.

[0091] The content of the structural unit (II) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, based on all structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. By setting the content of the structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0092] [Structural unit (III)] The base resin optionally contains other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding those corresponding to the structural unit (II)). By further containing the structural unit (III), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0093] Examples of the structural unit (III) include structural units represented by the following formula:

[0094] [ka]

[0095] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0096] When the base resin has the structural unit (III) having the polar group, the content of the structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, based on the total structural units constituting the base resin. Also, the content is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content of the structural unit (III) within the above range, the lithography performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0097] Structural Unit (IV) In addition to the structural unit (III) having the polar group, the base resin optionally contains a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of these are collectively referred to as "structural unit (IV)"). The structural unit (IV) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This resin is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. In this case, the resin preferably contains structural unit (I) and / or structural unit (III) in addition to structural unit (IV).

[0098] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-labile group, and then to obtain structural unit (IV) by deprotection through hydrolysis. The structural unit that gives structural unit (IV) upon hydrolysis is preferably represented by the following formula (4-1) or (4-2).

[0099] [ka]

[0100] 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.12 The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0101] 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.

[0102] In the case of a resin intended for exposure to radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total structural units constituting the resin, and is preferably 70 mol % or less, more preferably 60 mol % or less.

[0103] (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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 4,000 or more. Furthermore, Mw is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 15,000 or less, and particularly preferably 12,000 or less. If the Mw of the base resin is less than the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is greater than the upper limit, the developability of the resist film may be reduced.

[0108] 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.

[0109] The Mw and Mn of the resin in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0110] 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

[0111] 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.

[0112] (other resins) The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0113] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have the structural unit (I) or the structural unit (II) in the above base resin, as necessary.

[0114] [ka]

[0115] In the above formula (5), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0116] Above R 13 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0117] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferred, and -COO- is more preferred.

[0118] 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.

[0119] 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.

[0120] 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-hexafluoro-2-propyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0121] When the high-fluorine-content resin has the structural unit (V), the content of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, based on the total structural units constituting the high-fluorine-content resin. Also, the content is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0122] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V): By having the structural unit (f-2), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0123] [ka]

[0124] The structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0125] When the structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (x) an alkali-soluble group, it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (VI) having (x) an alkali-soluble group, A 1 is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0126] When the structural unit (VI) has an alkali-dissociable group (y), R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1or R F is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has 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 (VI) 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.

[0127] R C As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0128] 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.

[0129] When the high-fluorine-content resin has the structural unit (VI), the content of the structural unit (VI) is preferably 50 mol% or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more, based on all structural units constituting the high-fluorine-content resin. Also, the content is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0130] Other structural units The high fluorine content resin may contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the structural units listed above. [ka] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0131] In the above formula (6), R 2α The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) is 8 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and represented by the following formula can be suitably used.

[0132] When the high-fluorine-content resin contains the structural unit having the alicyclic structure, the content of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total structural units constituting the high-fluorine-content resin, and is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 450 mol% or less.

[0133] The Mw of the high fluorine content resin is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more. The Mw is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 15,000 or less, and particularly preferably 12,000 or less.

[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 1.9.

[0135] The content of the high-fluorine content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base resin, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0136] By setting the content of the high-fluorine-content resin within the above range, the high-fluorine-content resin can be more effectively distributed unevenly on the surface layer of the resist film, which in turn can improve the water repellency of the surface of the resist film during immersion lithography and modify the surface of the resist film. The radiation-sensitive resin composition may contain one or more high-fluorine-content resins.

[0137] (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.

[0138] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of this embodiment preferably further contains a radiation-sensitive acid generator that, upon irradiation (exposure), generates an acid with a lower pKa than the acid generated from the onium salt compound (1) or the like, which functions as the acid diffusion controller. This acid generator generates a relatively strong acid. When the resin contains a 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 the onium salt 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 the onium salt compound (1) and the radiation-sensitive acid generator is determined by factors such as the energy required to dissociate the acid-dissociable group of the structural unit (I) or the like of the resin and the thermal energy conditions applied when forming a pattern using the radiation-sensitive resin composition. 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.

[0139] 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.

[0140] Examples of the radiation-sensitive acid generator include onium salt compounds (excluding the above-mentioned onium salt 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.

[0141] The acid generated upon exposure can be one that generates a sulfonic acid upon exposure. Examples of such acids include sulfonium salts having an anion in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfo group. Among these, radiation-sensitive acid generators having cyclic structures in the cation and anion are particularly preferred.

[0142] These radiation-sensitive acid generators may be used alone or in combination of two or more. The content of the radiation-sensitive acid generator (when multiple types of radiation-sensitive acid generators are used in combination, the total content) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, the content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less, per 100 parts by mass of the resin. This allows for excellent sensitivity, LWR performance, and CDU performance to be exhibited during resist pattern formation.

[0143] (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.

[0144] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] (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.

[0153] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing the onium salt 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 having a pore size of about 0.05 μm to 0.2 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0154] <Pattern formation method> A pattern forming method according to one embodiment of the present invention includes: a step (1) of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film to light (hereinafter also referred to as the "exposure step"); The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0155] According to the above-described resist pattern forming method, a high-quality resist pattern can be formed because the above-described radiation-sensitive resin composition, which has excellent sensitivity in the exposure step, CDU performance, and LWR performance, is used. Each step will now be described.

[0156] [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.

[0157] 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.

[0158] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (I) and (IV) as the base resin in the composition.

[0159] [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.

[0160] 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.

[0161] 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.

[0162] [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.

[0163] 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.

[0164] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As ether solvents, glycol ether solvents are preferred, with ethylene glycol monomethyl ether and propylene glycol monomethyl ether being more preferred. As ester solvents, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As ketone solvents, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0165] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer, but it is preferable that the developer contains an alkaline aqueous solution and the resulting pattern is a positive pattern.

[0166] 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).

[0167] <Onium salt compound (1)> The onium salt compound according to yet another embodiment of the present invention is represented by the above formula (1).

[0168] As the onium salt compound represented by the formula (1) according to this embodiment, the onium salt compound (1) contained in the radiation-sensitive resin composition can be suitably used. [Example]

[0169] 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.

[0170] [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.

[0171] [ 13 C-NMR analysis] polymer 13 C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0172] <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 %.

[0173] [ka]

[0174] [Synthesis Example 1] (Synthesis of Resin (A-1)) Monomer (M-1), monomer (M-2), and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% relative to the total of 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered, and dried at 50°C for 24 hours to obtain a white powdery resin (A-1) (yield: 83%). The Mw of the resin (A-1) was 8,800, and the Mw / Mn was 1.50. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2) and (M-13) were 41.3 mol %, 13.8 mol % and 44.9 mol %, respectively.

[0175] [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 (the same applies to the following tables).

[0176] [Table 1]

[0177] [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 a hydrolysis reaction was carried out at 70°C for 6 hours while stirring. 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 solidify the resin. The resulting solid was filtered and dried at 50°C for 13 hours to obtain a white powdery resin (A-12) (yield: 79%). The Mw of resin (A-12) was 5,200, and the Mw / Mn was 1.60. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1) and (M-18) were 51.3 mol % and 48.7 mol %, respectively.

[0178] [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.

[0179] [Table 2]

[0180] [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. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.

[0181] [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.

[0182] [Table 3]

[0183] <Synthesis of onium salt compounds> [Synthesis Example 21] (Synthesis of onium salt compound (C-1)) The onium salt compound (C-1) was synthesized according to the following synthesis scheme.

[0184] [ka]

[0185] 20.0 mmol of 6-bromo-5,5,6,6-tetrafluorohexan-1-ol, 30.0 mmol of 1-(tert-butoxycarbonyl)-4-piperidinecarboxylic acid, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride were added to a reaction vessel and stirred at room temperature for 4 hours. After dilution with water, methylene chloride was added for extraction, and 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 evaporated, and the bromo-form was obtained in good yield by purification by column chromatography.

[0186] A mixture of acetonitrile and water (1:1 (mass ratio)) was added to the above brominated product to prepare a 1 M solution, and then 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added and the mixture was allowed to react at 70°C for 4 hours. After extraction with acetonitrile and distillation of the solvent, a mixture of acetonitrile and water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 60.0 mmol of aqueous hydrogen peroxide and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50°C for 12 hours. Extraction with acetonitrile and distillation of the solvent yielded a sodium sulfonate salt compound. 20.0 mmol of triphenylsulfonium bromide was added to the above sodium sulfonate salt compound, and a mixture of water and dichloromethane (1:3 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain the onium salt compound (C-1) represented by the above formula (C-1) in good yield.

[0187] [Synthesis Examples 22 to 44] (Synthesis of Compounds (C-2) to (C-24)) Onium salts represented by the following formulae (C-2) to (C-24) were synthesized in the same manner as in Synthesis Example 21, except that the raw materials and precursors were changed as appropriate.

[0188] [ka]

[0189] [Onium salt compounds other than onium salt compounds (C-1) to (C-24)] cc-1 to cc-12: Onium salt compounds represented by the following formulas (cc-1) to (cc-12) (hereinafter, the onium salt compounds represented by formulas (cc-1) to (cc-12) may be referred to as "onium salt compound (cc-1)" to "compound (cc-12)," respectively.)

[0190] [ka]

[0191] [[B] Radiation-sensitive acid generator] B-1 to B-6: Compounds represented by the following formulas (B-1) to (B-6) (hereinafter, the compounds represented by formulas (B-1) to (B-6) may be referred to as "compound (B-1)" to "compound (B-6)", respectively.)

[0192] [ka]

[0193] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-butyrolactone D-4: Ethyl lactate

[0194] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] A radiation-sensitive resin composition (J-1) was prepared by mixing 100 parts by mass of (A-1) as the resin [A], 12.0 parts by mass of (B-1) as the radiation-sensitive acid generator [B], 5.0 parts by mass of (C-1) as the acid diffusion controller [C], 3.0 parts by mass (solids content) of (E-1) as the high-fluorine-content resin [E], and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0195] [Examples 2 to 51 and Comparative Examples 1 to 12] Radiation-sensitive resin compositions (J-2) to (J-51) and (CJ-1) to (CJ-12) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 4 below were used.

[0196] [Table 4]

[0197] <Formation of resist pattern using positive radiation-sensitive resin composition for ArF exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), a composition for forming an underlayer antireflection film ("ARC66" of Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlayer antireflection film with an average thickness of 100 nm. On this underlayer antireflection film, the prepared positive radiation-sensitive resin composition for ArF exposure was applied using the above spin coater, and PB (pre-bake) was performed at 100 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, for this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" of ASML), under the optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7), exposure was performed through a mask pattern of 40 nm line and space. After exposure, PEB (post-exposure bake) was performed at 100 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive resist pattern (40 nm line and space pattern).

[0198] <Evaluation> Regarding the resist pattern formed using the above positive radiation-sensitive resin composition for ArF exposure, the sensitivity and LWR performance were evaluated according to the following methods. The results are shown in Table 5 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" of Hitachi High-Technologies Corporation) was used.

[0199] [Sensitivity] In the formation of the resist pattern using the above positive radiation-sensitive resin composition for ArF exposure, the exposure amount for forming a 40 nm line and space pattern was taken as the optimum exposure amount, and this optimum exposure amount was defined as the sensitivity (mJ / cm 2 )). The sensitivity was 25 mJ / cm 2The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0200] [LWR performance] A 40 nm line-and-space resist pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation above. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 3.0 nm or less, and "poor" when it exceeded 3.0 nm.

[0201] [Table 5]

[0202] As is clear from the results in Table 5, the radiation-sensitive resin compositions of the Examples exhibited good sensitivity and LWR performance when used in ArF exposure, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive resin compositions of the Examples are used in ArF exposure, resist patterns with high sensitivity and good LWR performance can be formed.

[0203] [Preparation of Positive-Working Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 52] A radiation-sensitive resin composition (J-52) was prepared by mixing 100 parts by mass of (A-12) as the resin [A], 15.0 parts by mass of (B-1) as the radiation-sensitive acid generator [B], 3.0 parts by mass of (C-1) 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.

[0204] [Examples 53 to 62 and Comparative Examples 13 to 16] Except for using the components of the types and contents shown in Table 6 below, radiation-sensitive resin compositions (J-53) to (J-62) and (CJ-13) to (CJ-16) were prepared in the same manner as in Example 52.

[0205]

Table 6

[0206] <Formation of resist pattern using positive-type radiation-sensitive resin composition for EUV exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), a composition for forming an underlying antireflective film ("ARC66" of Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlying antireflective film with an average thickness of 105 nm. On this underlying antireflective film, the positive-type radiation-sensitive resin composition for EUV exposure prepared above was applied using the above spin coater, and PB was performed at 130 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 55 nm was formed. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" of ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (32 nm line and space pattern).

[0207] <Evaluation> Regarding the resist pattern formed using the above positive-type radiation-sensitive resin composition for EUV exposure, the sensitivity and LWR performance were evaluated according to the following methods. The results are shown in Table 7 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" of Hitachi High-Technologies Corporation) was used.

[0208] [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".

[0209] [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 32 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR performance was evaluated as "good" when it was 3.0 nm or less, and "poor" when it exceeded 3.0 nm.

[0210] [Table 7]

[0211] 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.

[0212] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 63] A radiation-sensitive resin composition (J-63) was prepared by mixing 100 parts by mass of (A-6) as the resin [A], 10.0 parts by mass of (B-5) as the radiation-sensitive acid generator [B], 2.0 parts by mass of (C-1) as the acid diffusion controller [C], 1.0 part by mass (solids content) of (E) as the high fluorine-content resin [E-4], and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0213] A 12-inch silicon wafer was coated with a bottom anti-reflective coating composition (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 100 nm. The negative radiation-sensitive resin composition for ArF exposure (J-63) prepared above was then coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 100°C for 60 seconds. The wafer was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a mask pattern with 40 nm holes and a 105 nm pitch. After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 100° C. Then, the resist film was developed using n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0214] <Evaluation> The resist patterns formed using the negative radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity and CDU performance according to the following methods. The resist pattern lengths were measured using a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation).

[0215] [sensitivity] In forming a resist pattern using the negative radiation-sensitive resin composition for ArF exposure, the exposure dose required to form a 40 nm hole pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 ) was decided.

[0216] [CDU performance] A resist pattern with 40 nm holes and a 105 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the above-mentioned scanning electron microscope. The dimensional variation (3σ) was calculated and used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better performance.

[0217] The resist patterns formed using the negative-tone radiation-sensitive resin compositions for ArF exposure were evaluated as described above. As a result, the radiation-sensitive resin composition of Example 63 exhibited good sensitivity and CDU performance even when a negative-tone resist pattern was formed by ArF exposure.

[0218] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 64] A radiation-sensitive resin composition (J-64) was prepared by mixing 100 parts by mass of (A-13) as the resin [A], 20.0 parts by mass of (B-6) as the radiation-sensitive acid generator [B], 10.0 parts by mass of (C-1) as the acid diffusion controller [C], 7.0 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.

[0219] 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-64) 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).

[0220] The resist pattern formed using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern formed using the negative-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 64 had good sensitivity and CDU performance, even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0221] 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

[Claim 1] An onium salt compound represented by the following formula (1): 【Chemistry 1】 (In the above formula (1), R １ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. ２ and R ３ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R ２ and R ３ and represent a cyclic structure having 3 to 20 ring members formed by combining them together with the carbon atoms to which they are bonded. R ４ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and L １ is a substituted or unsubstituted alkanediyl group having 1 to 8 carbon atoms, or R ４ and L １ represents a group containing a pyrrolidine structure or a piperidine structure formed by combining together with the nitrogen atom to which they are bonded. L ２ is an unsubstituted divalent chain hydrocarbon group having 1 to 10 carbon atoms. R ｆ１ and R ｆ２ are each independently a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. ｆ１ and R ｆ２ When there are multiple R ｆ１ and R ｆ２ are the same or different from each other. n is an integer of 1 to 4. Z ＋ is a monovalent radiation-sensitive onium cation.

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