Radiation-sensitive resin composition, pattern forming method, and onium salt compound

Abstract

A radiation-sensitive resin composition which exhibits sufficient sensitivity, LWR performance and CDU performance, a pattern forming method and an onium salt compound are provided. This radiation-sensitive resin composition comprises an onium salt compound represented by formula (1), a resin including a structural unit having an acid-dissociable group, and a solvent. (In formula (1), Rf represents a fluorine atom or a C1-10 monovalent fluorinated hydrocarbon group. Each of R1-R3 independently represents a hydrogen atom or a C1-20 monovalent hydrocarbon group having, or alternatively, two of R1 to R3 are combined with each other and represent a C3-20 ring structure configured together with a carbon atom where these bond together. n is an integer of 1-4. When n is 2 or more, the R2 and R3 groups are the same or different. Z+ represents a monovalent radiation-sensitive onium cation.)

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive resin composition, a patterning method, and an onium salt compound.

Background Art

[0002] Photolithography technology using a resist composition for forming fine circuits in semiconductor elements is utilized. As a typical procedure, for example, acid is generated by exposure through radiation irradiation via a mask pattern to a film of the resist composition, and a difference in solubility of the resin in an alkaline or organic developer between the exposed portion and the unexposed portion is caused by a reaction using the acid as a catalyst, thereby forming a resist pattern on a substrate.

[0003] In the above photolithography technology, radiation with a short wavelength such as an ArF excimer laser is used, or a liquid immersion lithography method (liquid immersion lithography) in which the space between the lens of an exposure apparatus and the resist film is filled with a liquid medium and exposure is performed is used to promote pattern miniaturization.

[0004] While efforts are underway for further technological progress, a technique has been proposed in which a quencher (acid diffusion controller) is blended into a resist composition to capture the acid diffused to the unexposed portion by a salt exchange reaction and improve the lithography performance by ArF exposure (Patent Document 1). In addition, as a next-generation technology, lithography using radiation with a shorter wavelength such as an electron beam, X-ray, and EUV (extreme ultraviolet ray) is also being studied.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Among such efforts toward next-generation technologies, resist performance equivalent to or better than that of conventional products is required in terms of, for example, line width roughness (LWR) performance, which indicates variations in sensitivity and line widths of resist patterns, and critical dimension uniformity (CDU) performance, which is an index of the uniformity of line widths and hole diameters. However, these characteristics have not been obtained at sufficient levels with existing radiation-sensitive resin compositions.

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

Means for Solving the Problems

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

[0009] That is, in one embodiment, the present invention relates to a radiation-sensitive resin composition containing an onium salt compound represented by the following formula (1) (hereinafter, also referred to as "onium salt compound (1)"), a resin containing a structural unit having an acid dissociable group, a solvent and.

Chemical formula

[0010] Since the radiation-sensitive resin composition contains an onium salt compound (1) as a quencher (acid diffusion controller), it can exhibit excellent sensitivity, LWR performance, and CDU performance during resist pattern formation. Although not bound by any theory, the reason for this is that the onium salt compound (1) has high transparency (low absorbance in the exposure wavelength band) in the resist film, resulting in good sensitivity. At the same time, the fluorine atom or fluorinated hydrocarbon group and the carboxylic acid anion are appropriately separated, and the number of fluorine atoms or fluorinated hydrocarbon groups is one (resulting in the destabilization of the carboxylic acid anion and the stabilization of the hydroxy group), which relatively increases the basicity of the onium salt compound (1) and affects the high acid-capturing property in the unexposed area.

[0011] In another embodiment of the present invention, a step of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition onto a substrate, a step of exposing the resist film, a step of developing the exposed resist film with a developer and a pattern forming method including the above steps.

[0012] In the pattern forming method, since the radiation-sensitive resin composition excellent in sensitivity, LWR performance, and CDU performance is used, a high-quality resist pattern can be efficiently formed.

[0013] In still another embodiment of the present invention, it relates to an onium salt compound represented by the following formula (1) (that is, onium salt compound (1)).

Chemical formula

[0014] Since the onium salt compound (1) can exhibit transparency and strong basicity in the resist film, when it is blended in a radiation-sensitive resin composition, excellent sensitivity, LWR performance, and CDU performance during resist pattern formation can be imparted to the composition.

Mode for Carrying Out 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 "composition") contains a predetermined onium salt compound (1), a resin, and a solvent. Further, if necessary, it contains a radiation-sensitive acid generator. The above composition may contain other optional components as long as the effects of the present invention are not impaired. By containing a predetermined onium salt compound (1), the radiation-sensitive resin composition can be imparted with high levels of sensitivity, LWR performance, and CDU performance.

[0017] (Onium Salt Compound (1)) The above onium salt compound (1) can function as a quencher (also referred to as a "photodecomposable base" or an "acid diffusion controller") that captures an acid in the pre-exposure or unexposed portion. The onium salt compound (1) is represented by the following formula (1).

[0018] [Chemical formula] (In the above formula (1), R f is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. R 1 ~R 3 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or two of R 1 ~R 3 are combined with each other to represent a cyclic structure having 3 to 20 carbon atoms formed together with the carbon atoms to which they are bonded. n is an integer of 1 to 4. When n is 2 or more, a plurality of R 2 and R 3 are the same as or different from each other. Z + is a monovalent radiation-sensitive onium cation.)

[0019] In the above formula (1), examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R f include a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the like.

[0020] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms include fluorinated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoro n-propyl group, heptafluoro i-propyl group, nonafluoro n-butyl group, nonafluoro i-butyl group, nonafluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoro n-pentyl group, tridecafluoro n-hexyl group, 5,5,5-trifluoro-1,1-diethylpentyl group; fluorinated alkenyl groups such as trifluoroethenyl group, pentafluoropropenyl group; Examples thereof include fluorinated alkynyl groups such as fluoroethynyl group and trifluoropropynyl group.

[0021] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornil group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, and fluorotetracyclodecyl group; fluorinated cycloalkenyl groups such as fluorocyclopentenyl group and nonafluorocyclohexenyl group.

[0022] As the fluorinated hydrocarbon group, a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms is preferable, a monovalent fluorinated alkyl group having 1 to 10 carbon atoms is more preferable, a perfluoroalkyl group having 1 to 6 carbon atoms is still more preferable, and a linear perfluoroalkyl group having 1 to 6 carbon atoms is particularly preferable.

[0023] In the above formula (1), R 1 , R 2 and R 3 The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by 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, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0024] 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, or a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

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

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

[0027] R 1 ~R 3 Examples of the cyclic structure having 3 to 20 carbon atoms formed by combining two of R~R and together with the carbon atom to which they are bonded include a structure obtained by further removing one hydrogen atom from the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0028] From the viewpoint of increasing the basicity of the onium salt compound (1) to efficiently control the diffusion of the acid, in order to suppress the stabilization of the carboxylic acid anion by the electron-withdrawing fluorine atom or fluorinated hydrocarbon group, n in the above formula (1) is an integer of 1 or more.

[0029] On the other hand, if the basicity of the onium salt compound (1) is too high, it becomes difficult to stably exist as a salt. Therefore, from the viewpoint that the hydroxy group easily stabilizes the carboxylic acid anion via intramolecular hydrogen bonding, n in the above formula (1) is preferably an integer of 1 to 3, more preferably 1 or 2, and particularly preferably 1.

[0030] Further, from the viewpoint of keeping the basicity and structure of the onium salt compound (1) constant, in order to form only specific intramolecular hydrogen bonds, R in the above formula (1) f and R 1 ~R 3 are all preferably free of hydroxy groups (that is, the anion moiety has only one hydroxy group).

[0031] Although the anion moiety of the onium salt compound (1) represented by the above formula (1) is not particularly limited, examples thereof include structures represented by the following formulas (1a) to (1z).

[0032]

Chemical formula

[0033]

Chemical formula

[0034]

Chemical formula

[0035] In the above formula (1), the above Z +Examples of the monovalent radiation-sensitive onium cation represented by include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples thereof include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, and the like. Among them, sulfonium cations or iodonium cations are preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0036]

Chemical formula

[0037]

Chemical formula

[0038]

Chemical formula

[0039]

Chemical formula

[0040]

Chemical formula

[0041]

Chemical formula

[0042] In the above formula (X-1), R a1 , R a2 and R a3is, independently of one another, a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -S-R T or represents 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 forming the skeleton. R P , R Q and R T are, independently of one another, 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 from 0 to 5. R a1 ~R a3 as well as R P , R Q and R T when each is plural, the plural R a1 ~R a3 as well as R P , R Q and R T may each be the same or different.

[0043] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k When n k is 0, k4 is an integer from 0 to 4, and when n b1 is 1, k4 is an integer from 0 to 7. When R b1 is plural, the plural R b1may represent a ring structure configured to fit together with each other. R b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. L C is a single bond or a divalent linking group. k5 is an integer from 0 to 4. R b2 When there are a plurality of R b2 they may be the same or different, and a plurality of R b2 may represent a ring structure configured to fit together with each other. q is an integer from 0 to 3. In the formula, S + The ring structure containing may contain heteroatoms such as O or S between the carbon-carbon bonds forming the skeleton.

[0044] 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.

[0045] In the above formula (X-4), R g1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k2 When n k2 is 0, k10 is an integer from 0 to 4, and when n k2 is 1, k10 is an integer from 0 to 7. R g1 When there are a plurality of R g1 they may be the same or different, and a plurality of R g1 may represent a ring structure configured to fit together with each other. R g2 and R g3is, independently of each other, 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 represents a ring structure formed by combining these groups with each other. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 When there are a plurality of each of R g2 and R g3 may be the same as or different from each other.

[0046] In the above formula (X-5), R d1 and R d2 are, independently of each other, 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, a nitro group, or represents a ring structure formed by combining two or more of these groups with each other. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 When there are a plurality of each of R d1 and R d2 may be the same as or different from each other.

[0047] In the above formula (X-6), R e1 and R e2 are, independently of each other, 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.

[0048] The onium salt compound (1) is formed by any combination of the anion moiety defined by the above formula (1) and the monovalent radiation-sensitive onium cation. Specific examples of the onium salt compound (1) include, but are not particularly limited to, structures represented by the following formulas (1-1) to (1-26).

[0049] [Chemical formula]

[0050] [Chemical formula]

[0051] [Chemical formula]

[0052] [Chemical formula]

[0053] Among them, the onium salt compounds (1) represented by the above formulas (1-1), (1-4), (1-5), (1-7) to (1-20), and (1-23) to (1-25) are preferred.

[0054] The content of the onium salt compound (1) in the radiation-sensitive resin composition according to this embodiment (in the case of using a plurality of onium salt compounds in combination, the total thereof) is preferably 0.01 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin described later. The above content is more preferably 25 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Also, 0.05 part by mass or more is more preferable, 0.1 part by mass or more is further preferable, and 0.5 part by mass or more is particularly preferable. The content of the onium salt compound (1) is appropriately selected according to the type of resin used, exposure conditions, required sensitivity, and the type and content of the radiation-sensitive acid generator described later. Thereby, excellent sensitivity, LWR performance, and CDU performance can be exhibited during resist pattern formation.

[0055] (Synthesis method of onium salt compound (1)) As the onium salt compound (1), taking the case where all of R 1 ~R 3 are hydrogen atoms and n is 1 as an example. Typically, as shown in the following scheme, the ketone of the fluorinated ketoester is converted to an alcohol with a reducing agent (sodium borohydride as a hydride complex in the scheme), then the ester moiety is hydrolyzed with an alkali, and finally, the onium salt compound (1) of interest can be synthesized by reacting with an onium cation halide corresponding to the onium cation moiety to proceed with salt exchange.

[0056] [Chemical formula] (In the formula, R 1 and Z + are synonymous with the above formula (1). M is an alkali metal. Hal - is a halide ion.)

[0057] For onium salt compounds (1) having other structures, they can be synthesized in the same way by appropriately selecting the fluorinated ketoester, reducing agent, and precursor corresponding to the onium cation moiety that form the basis of the anion moiety. For example, by using a Grignard reagent instead of the hydride complex that is a ketone reducing agent, a hydrocarbon group can be introduced as R 1 .

[0058] (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, this resin is also referred to as "base resin"). The "acid dissociable group" is a group that substitutes a hydrogen atom of a carboxy group, phenolic hydroxyl group, alcoholic hydroxyl group, sulfo group, etc., and dissociates by the action of an acid. The radiation-sensitive resin composition is excellent in pattern formability because the resin has structural unit (I).

[0059] 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 described later, and may have other structural units other than the structural units (I) and (II). Hereinafter, each structural unit will be described.

[0060] [Structural unit (I)] 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. For example, a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, a structural unit having an acetal bond, etc. can be mentioned. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, the structural unit represented by the following formula (3) (hereinafter, also referred to as "structural unit (I-1)") is preferable.

[0061] [Chemical formula]

[0062] In the above formula (3), R 7 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 9 and R 10 are each independently a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are combined with each other and together with the carbon atom to which they are bonded, represent a divalent alicyclic group having 3 to 20 carbon atoms.

[0063] As the above R 7 , from the viewpoint of the copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0064] The above R 8Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0065] The above R 8 ~R 10 Examples of the linear hydrocarbon group having 1 to 10 carbon atoms represented by include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0066] The above R 8 ~R 10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by include a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group. Preferred examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms among the carbon atoms constituting the alicyclic ring are bonded by a bonding chain containing one or more carbon atoms.

[0067] The above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by include, for example, aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group, and the like.

[0068] The above R 8 Preferably, is a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0069] The above R 9 and R 10The divalent alicyclic group having 3 to 20 carbon atoms formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula and the carbon atoms to which they are attached is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above number of carbon atoms. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used. As the polycyclic hydrocarbon group, either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group may be used, and either a saturated hydrocarbon group or an unsaturated hydrocarbon group may be used. The condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed by sharing sides (bonds between two adjacent carbon atoms) of a plurality of alicyclic rings.

[0070] Among the monocyclic alicyclic hydrocarbon groups, as the saturated hydrocarbon group, a cyclopentanediy group, a cyclohexanediy group, a cycloheptanediy group, a cyclooctanediy group, etc. are preferable, and as the unsaturated hydrocarbon group, a cyclopentenediy group, a cyclohexenediy group, a cycloheptenediy group, a cyclooctenediy group, a cyclodecenediy group, etc. are preferable. As the polycyclic alicyclic hydrocarbon group, a bridged alicyclic saturated hydrocarbon group is preferable. For example, a bicyclo[2.2.1]heptane-2,2-diyl group (norbornane-2,2-diyl group), a bicyclo[2.2.2]octane-2,2-diyl group, a tricyclo[3.3.1.1 3,7 decane-2,2-diyl group (adamantane-2,2-diyl group), etc. are preferable.

[0071] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and it is preferable that the alicyclic structure formed by combining R 9 and R 10 and the carbon atom to which they are attached is a polycyclic or monocyclic cycloalkane structure.

[0072] 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)").

[0073]

Chemical formula

[0074] In the above formulas (3-1) to (3-6), R 7 ~R 10 is synonymous with the above formula (3). i and j are each independently an integer from 1 to 4. k and l are 0 or 1.

[0075] As i and j, 1 is preferable. R 8 is preferably a methyl group, an ethyl group or an isopropyl group. R 9 and R 10 are preferably a methyl group or an ethyl group.

[0076] The base resin may contain one or more combinations of structural units (I).

[0077] The content ratio of the structural unit (I) (when including a plurality of types, the total content ratio) is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, and particularly preferably 35 mol% or more with respect to all the structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, still more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content ratio of the structural unit (I) within the above range, the pattern forming property of the radiation-sensitive resin composition can be further improved.

[0078] [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 having the structural unit (II) in the base resin, the solubility in the developer can be adjusted. As a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. Also, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0079] Examples of the structural unit (II) include structural units represented by the following formulas (T-1) to (T-10).

[0080] [Chemical formula]

[0081] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 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. R L4 and R L5 may be a divalent alicyclic group having 3 to 8 carbon atoms formed together with the carbon atoms to which they are attached. L 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.

[0082] Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed together with the carbon atoms to which the above R L4 and R L5 are attached include groups having 3 to 8 carbon atoms among the divalent alicyclic groups having 3 to 20 carbon atoms formed by combining the chain hydrocarbon group or alicyclic hydrocarbon group represented by R 9 and R 10 in the above formula (3) together with the carbon atoms to which they are attached. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0083] Examples of the divalent linking group represented by the above L 2 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-.

[0084] Among these, as the structural unit (II), a structural unit containing a lactone structure is preferable, a structural unit containing a norbornane lactone structure is more preferable, and a structural unit derived from norbornane lactone-yl (meth)acrylate is even more preferable.

[0085] The content ratio 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 the 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 ratio of the structural unit (II) within the above range, the lithography performance such as resolution of the radiation-sensitive resin composition and the adhesion of the formed resist pattern to the substrate can be further improved.

[0086] [Structural unit (III)] In addition to the above structural units (I) and (II), the base resin optionally has other structural units. Examples of the other structural units include structural units (III) containing a polar group (excluding those corresponding to the structural unit (II)). By further having the structural unit (III), the solubility in the developer can be adjusted, and as a result, the lithography performance such as the resolution of the radiation-sensitive resin composition can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.

[0087] Examples of the structural unit (III) include structural units represented by the following formula.

[0088] [Chemical formula]

[0089] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0090] When the base resin has the structural unit (III) having the polar group, the content ratio of the structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and still more preferably 10 mol% or more with respect to all the structural units constituting the base resin. Also, it is preferably 40 mol% or less, more preferably 35 mol% or less, and still more preferably 30 mol% or less. By setting the content ratio of the structural unit (III) within the above range, the lithography performance such as the resolution of the radiation-sensitive resin composition can be further improved.

[0091] [Structural unit (IV)] The base resin may optionally have, as other structural units, a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both are also collectively referred to as "structural unit (IV)") in addition to the structural unit (III) having the polar group. The structural unit (IV) contributes to the improvement of the etching resistance and the improvement of the difference in the solubility in the developer (dissolution contrast) between the exposed portion and the unexposed portion. In particular, it can be suitably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less such as an electron beam or EUV. In this case, the resin preferably has the structural unit (I) together with the structural unit (IV).

[0092] In this case, at the time of polymerization, it is preferable to polymerize in a state where the phenolic hydroxyl group is protected by a protecting group such as an alkali-dissociable group, and then to perform hydrolysis for deprotection to obtain the structural unit (IV). As the structural unit that gives the structural unit (IV) by hydrolysis, it is preferably represented by the following formulas (4-1) and (4-2).

[0093] [Chemical formula]

[0094] 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. R 12is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. R 12 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms for R in structural unit (I) 8 include the monovalent hydrocarbon group having 1 to 20 carbon atoms for R. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a t-butoxy group.

[0095] As for the above R 12 an alkyl group and an alkoxy group are preferable, and among them, a methyl group and a t-butoxy group are more preferable.

[0096] In the case of a resin for exposure with radiation having a wavelength of 50 nm or less, the content ratio of structural unit (IV) is preferably 10 mol% or more, more preferably 20 mol% or more, with respect to all the structural units constituting the resin. Further, it is preferably 70 mol% or less, more preferably 60 mol% or less.

[0097] (Synthesis method of base resin) The base resin can be synthesized, for example, by polymerizing monomers giving each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0098] Examples of the radical polymerization initiator include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate; peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferable, and AIBN is more preferable. These radical initiators can be used alone or in combination of two or more.

[0099] Examples of the solvent used in the above 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; Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol, etc. The solvents used for these polymerizations may be used alone or in combination of two or more.

[0100] The reaction temperature in the above polymerization is usually 40°C to 150°C, preferably 50°C to 120°C. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0101] The molecular weight of the base resin is not particularly limited, but the polystyrene-equivalent weight average molecular weight (Mw) by gel permeation chromatography (GPC) is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less, even more preferably 3,000 or more and 15,000 or less, and particularly preferably 4,000 or more and 12,000 or less. If the Mw of the base resin is less than the above lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the base resin exceeds the above upper limit, the developability of the resist film may decrease.

[0102] The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the polystyrene-reduced number average molecular weight (Mn) of the base resin 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.

[0103] The Mw and Mn of the resin in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.

[0104] GPC column: 2 columns of G2000HXL, 1 column of G3000HXL, 1 column of G4000HXL (above, manufactured by Tosoh Corporation) Column temperature: 40 °C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0105] As the content ratio of the base resin, 70 mass% or more is preferable, 80 mass% or more is more preferable, and 85 mass% or more is still more preferable with respect to the total solid content of the radiation-sensitive resin composition.

[0106] (Other resins) The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content ratio of fluorine atoms than the above base resin (hereinafter, also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface layer of the resist film with respect to the above base resin, and as a result, the water repellency of the surface of the resist film during immersion exposure can be enhanced.

[0107] As the high-fluorine content resin, it preferably has a structural unit represented by the following formula (5) (hereinafter, also referred to as "structural unit (V)"), and may have the structural unit (I) or the structural unit (II) in the above base resin as necessary.

[0108] [Chemical]

[0109] In the above formula (5), R 13 is a hydrogen atom, a methyl group or a trifluoromethyl group. G L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. R 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0110] Regarding the above R 13 from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0111] Regarding the above G L from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferable, and -COO- is more preferable.

[0112] Regarding the above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the above include those in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0113] Regarding the above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above include those in which some or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms.

[0114] Regarding the above R 14 is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and further preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0115] When the high-fluorine content resin has the structural unit (V), the content ratio of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more, and particularly preferably 50 mol% or more with respect to all the structural units constituting the high-fluorine content resin. Further, it is preferably 95 mol% or less, more preferably 90 mol% or less, and still more preferably 85 mol% or less. By setting the content ratio of the structural unit (V) within the above range, the mass content ratio of fluorine atoms in the high-fluorine content resin can be adjusted more appropriately, and the uneven distribution on the surface layer of the resist film can be further promoted. As a result, the water repellency of the resist film during immersion exposure can be further improved.

[0116] 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 the structural unit (VI)) together with or in place 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.

[0117]

Chemical formula

[0118] The structural unit (VI) is roughly classified into two cases: (x) having an alkali-soluble group and (y) having a group that dissociates by the action of an alkali to increase solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). Commonly to both (x) and (y), in the above formula (f-2), R C is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R D is a single bond, a (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, an oxygen atom, a sulfur atom, -NR E -bonded to the terminal on the R dd side of this hydrocarbon group, a carbonyl group, -COO- or -CONH-, or a structure in which a part of the hydrogen atoms of this hydrocarbon group is substituted by an organic group having a hetero atom. R ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0119] When the structural unit (VI) has an (x) alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-*, or -SO2O-*. * indicates the bonding site to R F W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. When A 1 is an oxygen atom, W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which A 1 is bonded. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R F may be the same or different from each other. By having the (x) alkali-soluble group in the structural unit (VI), the affinity for the alkali developer can be increased, and development defects can be suppressed. As the structural unit (VI) having the (x) alkali-soluble group, it is particularly preferable that A 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0120] When the structural unit (VI) has a (y) alkali-dissociable group, 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. * indicates the bonding site to R F W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When A 1 is -COO-* or -SO2O-*, W 1or R F is A 1 has a fluorine atom on the carbon atom bonded to A or on a carbon atom adjacent thereto. When A 1 is an oxygen atom, W 1 and R E is a single bond, R D is a structure in which a carbonyl group is bonded to the end on the R side of a hydrocarbon group having 1 to 20 carbon atoms, and R E is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R F 's, W E , A 1 and R 1 and R F may be the same or different from each other. Since the structural unit (VI) has a (y) alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. As the structural unit (VI) having a (y) alkali-dissociable group, A 1 is -COO-*, and R F or W 1 or both of them having a fluorine atom are particularly preferred.

[0121] As R C , from the viewpoint of the copolymerizability of the monomer giving the structural unit (VI) and the like, a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0122] When R E is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is more preferred.

[0123] When the high-fluorine content resin has the structural unit (VI), the content ratio of the structural unit (VI) is preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more, based on all the structural units constituting the high-fluorine content resin. Further, it is preferably 95 mol% or less, more preferably 90 mol% or less, and still more preferably 85 mol% or less. By setting the content ratio of the structural unit (VI) within the above range, the water repellency of the resist film during liquid immersion exposure can be further improved.

[0124] [Other structural units] The high-fluorine content resin may contain, as structural units other than the above-listed structural units, a structural unit having an alicyclic structure represented by the following formula (6). [Chemical formula] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0125] In the above formula (6), as the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R 2α , the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R 8 in the above formula (1) can be preferably employed.

[0126] When the high-fluorine content resin contains the structural unit having the above alicyclic structure, the content ratio of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more, based on all the structural units constituting the high-fluorine content resin. Further, it is preferably 70 mol% or less, more preferably 60 mol% or less, and still more preferably 50 mol% or less.

[0127] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, still more preferably 3,000, and particularly preferably 5,000. The upper limit of the above Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000.

[0128] 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 above Mw / Mn is usually 5, preferably 3, more preferably 2, and still more preferably 1.9.

[0129] The content of the high fluorine content resin is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, still more preferably 1 part by mass or more, and particularly preferably 1.5 part by mass or more with respect to 100 parts by mass of the above base resin. Also, it is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0130] By setting the content of the high fluorine content resin within the above range, the high fluorine content resin can be more effectively unevenly distributed on the surface layer of the resist film, and as a result, the water repellency of the surface of the resist film during immersion exposure can be further enhanced. The radiation-sensitive resin composition may contain one or more high fluorine content resins.

[0131] (Synthesis method of high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the synthesis method of the above base resin.

[0132] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of this embodiment preferably further contains a radiation-sensitive acid generator that generates an acid with a pKa smaller than that of the acid generated from the onium salt compound (1) upon irradiation (exposure) with radiation, i.e., 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 carboxy group or the like. This function is different from the function of the onium salt compound (1) that suppresses the diffusion of the acid generated from the radiation-sensitive acid generator in the unexposed area without substantially dissociating the acid-dissociable group or the like of the resin structural unit (I) or the like under the pattern formation conditions using the radiation-sensitive resin composition. The difference in the functions of the onium salt compound (1) and the radiation-sensitive acid generator is determined by the energy required for the acid-dissociable group of the resin structural unit (I) or the like to dissociate and the thermal energy conditions applied when forming a pattern using the radiation-sensitive resin composition. As the form of the radiation-sensitive acid generator in the radiation-sensitive resin composition, it may exist alone as a compound (released from the polymer), incorporated as a part of the polymer, or in both of these forms, but the form of existing alone as a compound is preferred.

[0133] 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 alkali aqueous solution development, while it becomes poorly soluble in the developer in the case of organic solvent development.

[0134] Examples of the radiation-sensitive acid generator include onium salt compounds (excluding the above onium salt compound (1)), sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferred.

[0135] Examples of the acid generated by exposure include those that generate sulfonic acid upon exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfo group. Among them, those having a cyclic structure are particularly preferred as the radiation-sensitive acid generator.

[0136] These radiation-sensitive acid generators may be used alone or in combination of two or more. The content of the radiation-sensitive acid generator (in the case of a combination of multiple types of radiation-sensitive acid generators, the total thereof) is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, still more preferably 5 part by mass or more, with respect to 100 parts by mass of the base resin. Also, with respect to 100 parts by mass of the resin, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Thereby, excellent sensitivity, LWR performance, and CDU performance can be exhibited during resist pattern formation.

[0137] (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 the compound (1), the resin, and, if desired, the radiation-sensitive acid generator and the like.

[0138] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0139] Examples of the alcohol solvent include monohydric alcohol solvents having 1 to 18 carbon atoms such as i-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, diacetone alcohol; Polyhydric alcohol solvents with 2 to 18 carbon atoms such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, etc.; Examples include polyhydric alcohol partial ether solvents in which a part of the hydroxy groups of the above polyhydric alcohol solvents are etherified.

[0140] As ether solvents, for example, Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, etc.; Cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, etc.; Aromatic ring-containing ether solvents such as diphenyl ether, anisole (methyl phenyl ether), etc.; Examples include polyhydric alcohol ether solvents in which the hydroxy groups of the above polyhydric alcohol solvents are etherified.

[0141] As ketone solvents, for example, chain ketone solvents such as acetone, butanone, methyl-i-butyl ketone, etc.: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, methylcyclohexanone, etc.: Examples include 2,4-pentanedione, acetonylacetone, acetophenone, etc.

[0142] As amide solvents, for example, cyclic amide solvents such as N,N'-dimethylimidazolidinone, N-methylpyrrolidone, etc.; Examples include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, etc.

[0143] As ester solvents, for example, Monocarboxylic acid ester solvents such as n-butyl acetate, ethyl lactate, etc.; Polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, 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 polyvalent carboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0144] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbon solvents such as benzene, toluene, di-i-propylbenzene, and n-amylnaphthalene.

[0145] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0146] (Other optional components) In addition to the above components, the radiation-sensitive resin composition may also contain other optional components. Examples of the other optional components include crosslinking agents, uneven distribution promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used alone or in combination of two or more.

[0147] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups. In the baking step after the batch exposure step, it causes a crosslinking reaction in the resin component by an acid-catalyzed reaction, increases the molecular weight of the resin component, and thereby reduces the solubility of the pattern-exposed portion in the developer. Examples of the functional group include (meth)acryloyl group, hydroxymethyl group, alkoxymethyl group, epoxy group, vinyl ether group, and the like.

[0148] (Phase separation promoter) The phase separation promoter has the effect of more efficiently phase-separating the high-fluorine content resin on the resist film surface. By incorporating this phase separation promoter into the radiation-sensitive resin composition, the addition amount of the high-fluorine content resin can be made less than before. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, elution of components from the resist film into the immersion medium can be further suppressed, or immersion exposure can be performed at a higher speed by high-speed scanning, and as a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. Examples of such a phase separation promoter that can be used include low molecular weight compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point of 100°C or more at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, and the like.

[0149] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

[0150] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0151] Examples of the nitrile compound include succinonitrile and the like.

[0152] Examples of the polyhydric alcohol include glycerin and the like.

[0153] The content of the uneven distribution promoting agent is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, based on 100 parts by mass of the total amount of the resin in the radiation-sensitive resin composition. Also, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more uneven distribution promoting agents.

[0154] (Surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), Megafac F171, F173 (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd.), and the like. The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less based on 100 parts by mass of the resin.

[0155] (Compound containing an alicyclic skeleton) The compound containing an alicyclic skeleton has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, etc.

[0156] Examples of the alicyclic skeleton-containing compound include, for example, adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; lithocholic acid esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, and the like can be mentioned. The content of the alicyclic skeleton-containing compound in the above radiation-sensitive resin composition is usually 5 parts by mass or less with respect to 100 parts by mass of the resin.

[0157] (Sensitizer) The sensitizer exhibits an action of increasing the amount of acid generated from a radiation-sensitive acid generator or the like, and has an effect of improving the "apparent sensitivity" of the above radiation-sensitive resin composition.

[0158] Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the above radiation-sensitive resin composition is usually 2 parts by mass or less with respect to 100 parts by mass of the resin.

[0159] <Method for preparing a radiation-sensitive resin composition> The above-mentioned radiation-sensitive resin composition can be prepared, for example, by mixing an onium salt compound (1), a resin, a solvent, a radiation-sensitive acid generator, a high fluorine content resin, etc. at a predetermined ratio. After mixing, the above-mentioned radiation-sensitive resin composition is preferably filtered, for example, with a filter having a pore size of about 0.5 μm. The solid content concentration of the above-mentioned radiation-sensitive resin composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0160] <Pattern formation method> The pattern formation method according to one embodiment of the present invention is a step (1) of applying the above-mentioned radiation-sensitive resin composition directly or indirectly on a substrate to form a resist film (hereinafter, also referred to as "resist film formation step"), a step (2) of exposing the above-mentioned resist film (hereinafter, also referred to as "exposure step"), and a step (3) of developing the exposed resist film (hereinafter, also referred to as "development step").

[0161] According to the above-mentioned resist pattern formation method, since the above-mentioned radiation-sensitive resin composition excellent in sensitivity, CDU performance, and LWR performance in the exposure step is used, a high-quality resist pattern can be formed. Hereinafter, each step will be described.

[0162] [Resist film formation step] In this step (the above step (1)), a resist film is formed using the above radiation-sensitive resin composition. Examples of the substrate on which this resist film is formed include conventionally known ones such as silicon wafers, silicon dioxide, and wafers coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in, for example, Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448 may be formed on the substrate. Examples of the coating method include spin coating, casting coating, roll coating, etc. After coating, if necessary, prebaking (PB) may be performed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, preferably 80°C to 120°C. The PB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The film thickness of the formed resist film is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0163] When performing liquid immersion exposure, regardless of the presence or absence of a water-repellent polymer additive such as the high-fluorine content resin in the above radiation-sensitive resin composition, for the purpose of avoiding direct contact between the liquid immersion liquid and the resist film, a liquid immersion protective film insoluble in the liquid immersion liquid may be provided on the above-formed resist film. As the liquid immersion protective film, a solvent-peeling type protective film that is peeled off by a solvent before the development process (see, for example, Japanese Patent Application Laid-Open No. 2006-227632), or a developer-peeling type protective film that is peeled off simultaneously with the development in the development process (see, for example, WO2005-069076, WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peeling type liquid immersion protective film.

[0164] Further, when performing the exposure step, which is the next step, with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit (I) and the structural unit (IV) as the base resin in the above composition.

[0165] [Exposure Step] In this step (the above step (2)), the resist film formed in the resist film forming step which is the above step (1) is irradiated with radiation through a photomask (in some cases, through an immersion medium such as water) for exposure. As the radiation used for exposure, depending on the line width of the target pattern, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, γ-rays; charged particle beams such as electron beams and α-rays can be mentioned. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with a wavelength of 50 nm or less positioned as the next-generation exposure technology are even more preferred.

[0166] When exposure is performed by immersion exposure, examples of the immersion liquid used include water, fluorine-based inert liquids, etc. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a temperature coefficient of refractive index as small as possible to minimize the distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above viewpoints, it is preferable to use water from the viewpoints of easy availability and ease of handling. When using water, an additive that reduces the surface tension of water and increases the interfacial activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and has a negligible effect on the optical coating on the lower surface of the lens. Distilled water is preferably used as the water to be used.

[0167] After the above exposure, post-exposure baking (PEB) is performed, and it is preferable to promote the dissociation of the acid-dissociable groups of the resin, etc. generated from the radiation-sensitive acid generator by the acid generated in the exposed portion of the resist film. Due to this PEB, a difference in solubility in the developer occurs between the exposed portion and the unexposed portion. The PEB temperature is usually 50°C to 180°C, and preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[0168] [Development Step] In this step (the above step (3)), the resist film exposed in the above exposure step (step (2)) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse solution such as water or alcohol and then dry.

[0169] As the developer used for the above development, in the case of alkali development, for example, an aqueous alkali solution in which 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, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved can be mentioned. Among these, an aqueous TMAH solution is preferable, and a 2.38 mass% aqueous TMAH solution is more preferable.

[0170] In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing an organic solvent can be mentioned. Examples of the above organic solvent include one or more of the solvents listed as the solvent of the above radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferable. As the ether solvent, a glycol ether solvent is preferable, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferable. As the ester solvent, an acetate ester solvent is preferable, and n-butyl acetate and amyl acetate are more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The content of the organic solvent in the developer is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and particularly preferably 99 mass% or more. Examples of the components other than the organic solvent in the developer include water, silicone oil, etc.

[0171] As described above, the developer may be either an alkaline developer or an organic solvent developer. However, it is preferable that the developer contains an organic solvent and the resulting pattern is a negative pattern.

[0172] Examples of the development method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by raising the developer on the substrate surface by surface tension and allowing it to stand for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning a developer discharge nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method), and the like.

[0173] <onium salt compound (1)> The onium salt compound according to another embodiment of the present invention is represented by the following formula (1). [Chemical formula] (In the above formula (1), R f is a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. R 1 ~R 3 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or two of 1 R 3 ~R are combined with each other to represent a cyclic structure having 3 to 20 carbon atoms formed together with the carbon atom to which they are bonded. 2 n is an integer of 1 to 4. When n is 2 or more, a plurality of 3 R and R + are the same as or different from each other.

[0174] As the onium salt compound represented by the above formula (1) according to this embodiment, the onium salt compound (1) contained in the above radiation-sensitive resin composition can be preferably used. [Example]

[0175] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement methods of various physical property values are shown below.

[0176] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the above-described conditions. Also, the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0177] 13 [C-NMR analysis] For the 13 C-NMR analysis of the resin, a nuclear magnetic resonance apparatus ("JNM-Delta400" manufactured by JEOL Ltd.) was used.

[0178] [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 each comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass mean the values when the total mass of the monomers used is 100 parts by mass, and mol% means the values when the total number of moles of the monomers used is 100 mol%.

[0179] [Chemical formula]

[0180] [Synthesis Example 1] [Synthesis of resin (A-1)] ​Monomer (M-1), monomer (M-2), and monomer (M-10) were dissolved in 2-butanone (200 parts by mass) such that the molar ratio was 40 / 15 / 45 (mol%). AIBN (azobisisobutyronitrile) (3 mol% based on the total 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 purged with nitrogen for 30 minutes. Then, the inside of the reaction vessel was set to 80 °C, and the above monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to 30 °C or lower. 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, then filtered again, and dried at 50 °C for 24 hours to obtain a white powder polymer (A-1) (yield: 80%). The Mw of resin (A-1) was 8,700, and Mw / Mn was 1.49. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1), (M-2), and (M-10) were 39.9 mol%, 14.3 mol%, and 45.8 mol%, respectively.

[0181] [Synthesis Examples 2 to 11] (Synthesis of Resins (A-2) to (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and blending ratios shown in Table 1 below were used. The content ratios (mol%) of the respective structural units, yields (%), and physical property values (Mw and Mw / Mn) of the obtained resins are also shown in Table 1 below. Note that “-” in Table 1 below indicates that the corresponding monomer was not used (the same applies to the subsequent tables).

[0182]

Table 1

[0183] [Synthesis Example 12] (Synthesis of Resin (A-12)) The monomer (M-1) and the monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio was 50 / 50 (mol%). 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 purged with nitrogen for 30 minutes. Then, the temperature inside the reaction vessel was set to 80 °C, and the above monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was taken as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to 30 °C or lower. 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, then filtered and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70 °C for 6 hours while stirring. After the reaction was completed, the residual solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass) and dropped into water (500 parts by mass) to coagulate the resin. The obtained solid was filtered and dried at 50 °C for 13 hours to obtain a white powdery resin (A-12) (yield: 79%). The Mw of the resin (A-12) was 5,200, and Mw / Mn was 1.60. Also, 13 As a result of 13C-NMR analysis, the content ratios of the respective structural units derived from (M-1) and (M-18) were 51.3 mol% and 48.7 mol%, respectively.

[0184] [Synthesis Examples 13 to 15] (Synthesis of Resins (A-13) to (A-15)) Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the monomers of the types and blending ratios shown in Table 2 below were used. The content ratios (mol%) of the respective structural units, the yields (%), and the physical property values (Mw and Mw / Mn) of the obtained resins are shown together in Table 2 below.

[0185]

Table 2

[0186] [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) so that the molar ratio was 20 / 80 (mol %), and AIBN (4 mol %) was added as an initiator to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel and purged with nitrogen for 30 minutes. Then, the inside of the reaction vessel was set to 80 °C, and the above monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to a temperature of 30 °C or lower. After replacing the solvent with acetonitrile (400 parts by mass), hexane (100 parts by mass) was added and stirred, and the operation of recovering the acetonitrile layer was repeated 3 times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine-content resin (E-1) was obtained (yield: 69%). The Mw of the high-fluorine-content resin (E-1) was 6,000, and Mw / Mn was 1.62. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.

[0187] [Synthesis Examples 17 to 20] (Synthesis of High-Fluorine-Content Resins (E-2) to (E-5)) High-fluorine-content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 16, except that the monomers of the types and blending ratios shown in Table 3 below were used. The content ratios (mol %), yields (%), and physical property values (Mw and Mw / Mn) of the respective structural units of the obtained high-fluorine-content resins are shown in accordance with Table 3 below.

[0188]

Table 3

[0189] (Synthesis of Acid Diffusion Controller C (Onium Salt Compound (1))) [Example 1] (Synthesis of Compound (C-1)) Compound (C-1) was synthesized according to the following synthetic scheme.

[0190] [Chemical formula]

[0191] Ethyl pentafluoropropionylacetate (20.0 mmol), sodium borohydride (24.0 mmol), and toluene were added to a reaction vessel to make a 0.5 M solution, and then the mixture was reacted at room temperature for 3 hours. Thereafter, a saturated aqueous ammonium chloride solution was added to stop the reaction, and then ethyl acetate was added for extraction, and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was distilled off, and purification by column chromatography gave the β-hydroxy ester in good yield.

[0192] A mixed solution of acetonitrile:water (1:1 (mass ratio)) was added to 20.0 mmol of the above β-hydroxy ester to make a 1 M solution, and then 24.0 mmol of lithium hydroxide was added, followed by reaction at room temperature for 3 hours to obtain the lithium carboxylate salt.

[0193] 20.0 mmol of triphenylsulfonium chloride was added to 20.0 mmol of the above lithium carboxylate salt, and a mixed solution of water:dichloromethane (1:1 (mass ratio)) was added to make a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. After drying the obtained organic layer over sodium sulfate, the solvent was distilled off to obtain the compound (C-1) represented by the above formula (C-1).

[0194] [Examples 2 to 10] (Synthesis of Compounds (C-2) to (C-10)) Radiation-sensitive acid diffusion control agents represented by the following formulas (C-2) to (C-10) were synthesized in the same manner as in the synthesis example except that the raw materials and precursors were appropriately changed.

[0195] [Chemical formula]

[0196] [Example 11] (Synthesis of Compound (C-11)) Compound (C-11) was synthesized according to the following synthetic scheme.

[0197] [Chemical Formula]

[0198] Ethyl pentafluoropropionylacetate (20.0 mmol) and THF were added to a reaction vessel to form a 0.5 M solution, which was then cooled to -20°C. A THF solution of methylmagnesium bromide (20.0 mmol) was added dropwise and reacted for 3 hours. Then, a saturated aqueous ammonium chloride solution was added to stop the reaction, and ethyl acetate was added for extraction. The organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was distilled off, and the β-hydroxy ester was obtained in good yield by purification by column chromatography.

[0199] A mixed solution of acetonitrile:water (1:1 (mass ratio)) was added to 20.0 mmol of the above β-hydroxy ester to form a 1 M solution, and then 20.0 mmol of lithium hydroxide was added and reacted at room temperature for 3 hours to obtain a lithium carboxylate salt.

[0200] 20.0 mmol of triphenylsulfonium chloride was added to 20.0 mmol of the above lithium carboxylate salt, and a mixed solution of water:dichloromethane (1:1 (mass ratio)) was added to form 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 and then the solvent was distilled off to obtain Compound (C-11) represented by the above formula (C-11).

[0201] [Examples 12 - 13] (Synthesis of Compounds (C-12) - (C-13)) A radiation-sensitive acid diffusion controller represented by the following formulas (C-12) to (C-13) was synthesized in the same manner as in the synthesis example, except that the raw materials and precursors were appropriately changed.

[0202]

Chemical formula

[0203] [Radiation-sensitive acid diffusion controller other than compounds (C-1) to (C-13)] cc-1 to cc-9: Compounds represented by the following formulas (cc-1) to (cc-9) (hereinafter, the compounds represented by the formulas (cc-1) to (cc-9) may be referred to as "compound (cc-1)" to "compound (cc-9)", respectively).)

[0204]

Chemical formula

[0205] [[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 the formulas (B-1) to (B-6) may be referred to as "compound (B-1)" to "compound (B-6)", respectively).)

[0206]

Chemical formula

[0207] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-Butyrolactone D-4: Ethyl lactate

[0208] [Preparation of negative-type radiation-sensitive resin composition for ArF exposure] [Example 14] 100 parts by mass of (A-1) as a resin, 15.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 3.0 parts by mass of (C-1) as an acid diffusion controller, 5.0 parts by mass (solid content) of (E-1) as a high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) = 69 / 30 / 1 (mass ratio) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-14).

[0209] [Examples 15 to 54 and Comparative Examples 1 to 9] Except for using each component of the types and contents shown in Table 4 below, radiation-sensitive resin compositions (J-15) to (J-54) and (CJ-1) to (CJ-9) were prepared in the same manner as in Example 14.

[0210]

Table 4

[0211] [Formation of a resist pattern using a negative-type radiation-sensitive resin composition for ArF exposure] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming an underlayer antireflection film ("ARC66" from 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 105 nm. On this underlayer antireflection film, the prepared negative-type radiation-sensitive resin composition for ArF exposure was applied using the above spin coater, and PB (pre-bake) was performed at 90°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" from ASML), under the optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6), it was exposed through a mask pattern with a 40 nm space and a 105 nm pitch. After exposure, PEB (post-exposure bake) was performed at 90°C for 60 seconds. Then, using n-butyl acetate as an organic solvent developer, the above resist film was developed with an organic solvent and dried to form a negative-type resist pattern (40 nm line and space pattern). Also, except for changing the mask pattern, in the same manner as the above operations, a negative-type resist pattern (40 nm hole, 105 nm pitch) was formed.

[0212] <Evaluation> Regarding the resist patterns formed using the above negative-type radiation-sensitive resin composition for ArF exposure, the sensitivity, LWR performance, and CDU performance were evaluated according to the following methods. The results are shown in Table 5 below. For the measurement of the length of the resist pattern, a scanning electron microscope ("CG-5000" from Hitachi High-Technologies Corporation) was used.

[0213] [Sensitivity] In the formation of the resist pattern using the above negative-type radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 ). The sensitivity is "good" when it is 27 mJ / cm 2 or less, and 27 mJ / cm 2When it exceeded, it was evaluated as "defective".

[0214] [LWR performance] The mask size was adjusted to form a 40 nm line and space pattern by irradiating the optimum exposure dose obtained in the above sensitivity evaluation, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the above scanning electron microscope. The variation in line width was measured at 500 points in total, the 3-sigma value was obtained from the distribution of the measured values, and this 3-sigma value was defined as LWR (nm). The smaller the value of LWR, the smaller the roughness of the line and the better it is. The LWR performance was evaluated as "good" when it was 3.5 nm or less and "defective" when it exceeded 3.5 nm.

[0215] [CDU performance] A resist pattern with a 40 nm hole and a 105 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the above scanning electron microscope. The variation in dimensions (3σ) was obtained and defined as the CDU performance (nm). The smaller the value of CDU, the smaller the variation in hole diameter in the long period and the better it is. The CDU performance was evaluated as "good" when it was 4.5 nm or less and "defective" when it exceeded 4.5 nm.

[0216]

Table 5

[0217] As is clear from the results in Table 5, the radiation-sensitive resin composition of the example had good sensitivity, LWR performance, and CDU performance when used for ArF exposure, whereas in the comparative example, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used for ArF exposure, a resist pattern with high sensitivity and good LWR performance and CDU performance can be formed.

[0218] [Preparation of positive radiation-sensitive resin composition for extreme ultraviolet (EUV) exposure] [Example 55] 100 parts by mass of (A-12) as a resin, 20.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 4.0 parts by mass of (C-1) as an acid diffusion controller, 3.0 parts by mass of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) = 70 / 30 (mass ratio) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-55).

[0219] [Examples 56 to 65 and Comparative Examples 10 to 13] Radiation-sensitive resin compositions (J-56) to (J-65) and (CJ-10) to (CJ-13) were prepared in the same manner as in Example 55, except that the components of the types and contents shown in Table 6 below were used.

[0220]

Table 6

[0221] <Formation of a resist pattern using a positive-type radiation-sensitive resin composition for EUV exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming an underlayer antireflection film ("ARC66" from 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 105 nm. On this underlayer antireflection film, the prepared positive-type radiation-sensitive resin composition for EUV exposure 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" from ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as the alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (32 nm line and space pattern).

[0222] <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" from Hitachi High-Technologies Corporation) was used.

[0223] [Sensitivity] In the formation of the resist pattern using the above positive-type 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 defined as the sensitivity (mJ / cm 2 ). The sensitivity was evaluated as "good" when it was 30 mJ / cm 2 or less, and as "bad" when it exceeded 30 mJ / cm 2 .

[0224] [LWR Performance] The mask size was adjusted to form a 32 nm line-and-space pattern by irradiating the optimum exposure dose obtained in the above sensitivity evaluation, and a resist pattern was formed. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. The variation in line width was measured at 500 points in total, the 3-sigma value was obtained from the distribution of the measured values, and this 3-sigma value was defined as LWR (nm). The smaller the value of LWR, the smaller the line wobbling and the better the performance. The LWR performance was evaluated as "good" when it was 3.8 nm or less and "bad" when it exceeded 3.8 nm.

[0225]

Table 7

[0226] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example had good sensitivity and LWR performance when used for EUV exposure, whereas in the comparative example, each characteristic was inferior to that of the example.

[0227] [Preparation of a positive-type radiation-sensitive resin composition for ArF exposure, formation and evaluation of a resist pattern using this composition] [Example 66] 100 parts by mass of (A-4) as a resin, 12.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 2.5 parts by mass of (C-1) as an acid diffusion controller, 3.0 parts by mass (solid content) of (E-2) as a high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) = 69 / 30 / 1 (mass ratio) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-66).

[0228] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming an underlying antireflection film ("ARC66" from Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlying antireflection film with an average thickness of 105 nm. On this underlying antireflection film, the prepared positive-type radiation-sensitive resin composition for ArF exposure (J-66) was applied using the above spin coater, and PB (pre-bake) was performed at 90 °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" from ASML), under optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6), it was exposed through a mask pattern with a 40 nm space and a 105 nm pitch. After exposure, PEB (post-exposure bake) was performed at 90 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as the alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (40 nm line and space pattern).

[0229] Regarding the resist pattern using the above positive-type radiation-sensitive resin composition for ArF exposure, it was evaluated in the same manner as the evaluation of the resist pattern using the above negative-type radiation-sensitive resin composition for ArF exposure. As a result, even when the radiation-sensitive resin composition of Example 66 was used to form a positive-type resist pattern by ArF exposure, the sensitivity, LWR performance, and CDU performance were good.

[0230] [Preparation of a negative-type radiation-sensitive resin composition for EUV exposure, formation and evaluation of a resist pattern using this composition] [Example 67] 100 parts by mass of (A-12) as a resin, 21.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 5.0 parts by mass of (C-1) as an acid diffusion control agent, 3.0 parts by mass of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) = 70 / 30 (mass ratio) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-67).

[0231] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), after applying a composition for forming a lower layer antireflection film ("ARC66" of Brewer Science, Inc.), it was heated at 205°C for 60 seconds to form a lower layer antireflection film with an average thickness of 105 nm. On this lower layer antireflection film, the above-prepared negative-type radiation-sensitive resin composition (J-67) for EUV exposure 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 developed with an organic solvent developer of n-butyl acetate and dried to form a negative-type resist pattern (32 nm line and space pattern).

[0232] Regarding the resist pattern using the above negative-type radiation-sensitive resin composition for EUV exposure, it was evaluated in the same manner as the evaluation of the resist pattern using the above positive-type radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 67 had good sensitivity and LWR performance even when a negative-type resist pattern was formed by EUV exposure.

Industrial Applicability

[0233] According to the radiation-sensitive resin composition, pattern forming method, and onium salt compound described above, it has good sensitivity to exposure light and can form a resist pattern excellent in LWR performance and CDU performance. Therefore, these can be suitably used in the processing process of semiconductor devices and the like, which are expected to further progress in miniaturization in the future.

Claims

1. An onium salt compound represented by the following formula (1), a resin containing a structural unit having an acid dissociable group, a solvent and a radiation-sensitive resin composition containing the same. 【Chemical Formula 1】 (In the above formula (1), R ｆ is a fluorine atom or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. R １ to R ３ are each independently a hydrogen atom, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or two of R １ to R ３ together represent a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed together with the carbon atom to which they are bonded. n is an integer of 1 to 4. When n is 2 or more, a plurality of R ２ and R ３ are the same as or different from each other. Z ＋ is a monovalent radiation-sensitive onium cation. )

2. The radiation-sensitive resin composition according to Claim 1, wherein n is 1 or 2 in the above formula (1).

3. The radiation-sensitive resin composition according to Claim 1 or 2, wherein R ｆ is a perfluoroalkyl group having 1 to 6 carbon atoms in the above formula (1).

4. In the above formula (1), R １ is a hydrogen atom, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, R ２ and R ３ are each independently a hydrogen atom, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R ２ and R ３The radiation-sensitive resin composition according to any one of claims 1 to 3, which represents a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and composed of carbon atoms that are aligned with each other and bonded together.

5. In the above formula (1), R ｆ and R １ to R ３ All of them do not contain a hydroxy group, and the radiation-sensitive resin composition according to any one of claims 1 to 4.

6. The radiation-sensitive resin composition according to any one of claims 1 to 5, wherein the radiation-sensitive onium cation in the above formula (1) is each independently a sulfonium cation or an iodonium cation.

7. The radiation-sensitive resin composition according to any one of claims 1 to 6, further comprising a radiation-sensitive acid generator that generates an acid having a pKa smaller than that of the acid generated from the above onium salt compound upon irradiation with radiation.

8. The radiation-sensitive resin composition according to any one of claims 1 to 7, wherein the structural unit having the above acid dissociable group is represented by the following formula (2). 【Chemical formula 2】 (In the above formula (2), R ７ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ８ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ９ and R １０ each independently represent 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.)

9. A step of forming a resist film by applying the radiation-sensitive resin composition according to any one of claims 1 to 8 directly or indirectly on a substrate, A step of exposing the above resist film, A step of developing the exposed resist film with a developer A patterning method including the above.

10. The patterning method according to claim 9, wherein the development is performed with an organic solvent.

11. An onium salt compound represented by the following formula (1). 【Chemical formula 3】 (In the above formula (1), R ｆ is a fluorine atom or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. R １ to R ３ are each independently a hydrogen atom, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or two of R １ to R ３ are combined with each other to represent a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed together with the carbon atom to which they are bonded. n is an integer of 1 to 4. When n is 2 or more, a plurality of R ２ and R ３ are the same as or different from each other. Z ＋ is a monovalent radiation-sensitive onium cation. )

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