Radiation-sensitive composition, pattern forming method, and radiation-sensitive acid generator

Abstract

The invention provides a radiation-sensitive composition, a pattern forming method and a radiation-sensitive acid generator. The radiation-sensitive composition is capable of forming a resist film that can exhibit sufficient levels of sensitivity, LWR, pattern rectangularity, development defect performance, EL, CDU and pattern circularity. A radiation-sensitive composition containing an onium salt compound represented by formula (1), a polymer containing a structural unit having an acid-dissociable group, and a solvent. (In formula (1), W represents a C3-40 organic group having at least one ring structure. L is a (r + 1)-valent linking group, and r is an integer of 1-3. For p and q, when r is 1, each of p and q is an integer of 1-3, and when r is 2-3, each of a plurality of p and q is an integer of 0-3. Wherein, when r is 2-3, at least one of the plurality of p is 1 or more, and at least one of the plurality of q is 1 or more. M + is a monovalent onium cation. > # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive composition, a pattern forming method, and a radiation-sensitive acid generator. Background Art

[0002] In the formation of fine circuits of semiconductor elements, a lithography technique using a resist composition is utilized. As a representative process, for example, by interposing a mask pattern and irradiating a film of a resist composition with radiation to generate an acid, and by a reaction using the acid as a catalyst, a difference in solubility of the resin with respect to an alkaline or organic developer is generated between the exposed portion and the unexposed portion, whereby a resist pattern is formed on a substrate.

[0003] In the lithography technique, pattern miniaturization is advanced by using short-wavelength radiation such as an ArF excimer laser, or by using a liquid immersion exposure method (Liquid Immersion Lithography) in which exposure is further performed in a state where a space between a lens of an exposure apparatus and a resist film is filled with a liquid medium. As a next-generation technology, lithography using even shorter-wavelength radiation such as an electron beam, an X-ray, and an Extreme Ultraviolet (EUV) is also being studied.

[0004] In the formation of circuits of semiconductor elements based on the lithography technique, various studies have been conducted on a photoacid generator which is one of the main components of a resist composition (for example, Japanese Patent Application Laid-Open No. 2020-75910 and Japanese Patent No. 5083528).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-75910

[0008] Patent Document 2: Japanese Patent No. 5083528 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] Resist composition requirements include sensitivity, line width roughness (LWR) indicating the deviation of the line width or the line width of the resist pattern, pattern rectangularity indicating the rectangularity of the cross-sectional shape of the resist pattern, development defect performance, exposure latitude (EL), critical dimension uniformity (CDU) as an index of the uniformity of the aperture diameter, pattern circularity indicating the roundness of the hole shape, and other resist properties.

[0011] An object of the present invention is to provide a radiation-sensitive composition, a pattern forming method, and a radiation-sensitive acid generator, and the radiation-sensitive composition can form a resist film that can sufficiently exhibit sensitivity, LWR, pattern rectangularity, development defect performance, EL, CDU, and pattern circularity in a horizontal direction.

[0012] Technical means for solving the problem

[0013] The inventors of the present invention repeated their efforts to study in order to solve this problem, and as a result, they found that the above object can be achieved by adopting the following structure, and thus completed the present invention.

[0014] That is, in one embodiment, the present invention relates to a radiation-sensitive composition containing:

[0015] An onium salt compound represented by the following formula (1) (hereinafter, also referred to as "onium salt compound (1)"), a polymer containing a structural unit having an acid dissociable group, and

[0016] a solvent.

[0017] [Chemical formula 1]

[0018]

[0019] (In formula (1), W is an organic group having at least one ring structure and having 3 to 40 carbon atoms; L is an (r + 1)-valent linking group, and r is an integer of 1 to 3; regarding p and q, when r is 1, p and q are both integers of 1 to 3, and when r is 2 to 3, a plurality of p and q are respectively integers of 0 to 3; wherein, when r is 2 to 3, at least one of the plurality of p is 1 or more, and at least one of the plurality of q is 1 or more; M + is a monovalent onium cation)

[0020] By including the onium salt compound (1), the radiation-sensitive composition can form a resist film that can sufficiently exhibit excellent sensitivity, LWR, pattern rectangularity, development defect performance, EL, CDU, and pattern circularity in a horizontal direction. As a reason, although not bound by any theory, it is speculated as follows.

[0021] The anion of the onium salt compound (1) has a carboxyl group and a hydroxyl group. By the interaction of these groups with the polymer in the composition, the diffusion length of the generated acid can be moderately shortened, and LWR and EL can be improved. In addition, since the anion of the onium salt compound (1) has a carboxyl group and a hydroxyl group, the solubility in the developer is greatly improved, and the insoluble components can be reduced. Therefore, it is presumed that development defects can be more efficiently suppressed, and furthermore, various properties of the given resist can be exhibited.

[0022] In another embodiment, the present invention relates to a pattern forming method, which includes:

[0023] a step of directly or indirectly coating the radiation-sensitive composition on a substrate to form a resist film;

[0024] a step of exposing the resist film; and

[0025] a step of developing the exposed resist film with a developer.

[0026] In the above pattern forming method, since the radiation-sensitive composition capable of forming a resist film with excellent sensitivity, LWR, pattern rectangularity, development defect performance, EL, CDU and pattern circularity is used, a high-quality resist pattern can be efficiently formed.

[0027] In still another embodiment, the present invention relates to a radiation-sensitive acid generator represented by the following formula (1).

[0028] [Chemical formula 2]

[0029]

[0030] (In formula (1), W is an organic group having at least one ring structure and having 3 to 40 carbon atoms; L is an (r + 1)-valent linking group, and r is an integer of 1 to 3; regarding p and q, when r is 1, p and q are both integers of 1 to 3, and when r is 2 to 3, a plurality of p's and q's are respectively integers of 0 to 3; wherein, when r is 2 to 3, at least one of the plurality of p's is 1 or more, and at least one of the plurality of q's is 1 or more; M + is a monovalent onium cation)

[0031] Since the radiation-sensitive acid generator contains the onium salt compound (1) having the specific structure, it can impart good sensitivity, LWR, pattern rectangularity, development defect performance, EL, CDU and pattern circularity to the resist film obtained when used in the radiation-sensitive composition. Detailed embodiments

[0032] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. In addition, combinations of preferred embodiments are also preferred.

[0033] <Radiation-sensitive composition>

[0034] The radiation-sensitive composition (hereinafter, also simply referred to as "composition") of the present embodiment contains: an onium salt compound (1), a polymer containing a structural unit having an acid dissociable group, and a solvent. As long as the effects of the present invention are not impaired, the composition may also contain any other components. By containing a specific onium salt compound (1) as a radiation-sensitive acid generator, the radiation-sensitive composition can impart high levels of sensitivity, LWR, pattern circularity, development defect performance, EL, CDU, and pattern circularity to the resist film of the radiation-sensitive composition.

[0035] (Onium salt compound (1))

[0036] The onium salt compound (1) is represented by the formula (1) and functions as a radiation-sensitive acid generator that generates an acid upon irradiation with radiation. Due to the structure of the onium salt compound (1), it can also function as a radiation-sensitive strong acid generator and can also function as an acid diffusion control agent that generates an acid having a higher pKa than the acid generated by the radiation-sensitive strong acid generator upon irradiation with radiation. In the present invention, from the viewpoint of development defect performance, it is preferable to use the onium salt compound (1) as a radiation-sensitive strong acid generator. Hereinafter, the onium salt compound (1) as a radiation-sensitive strong acid generator will be described.

[0037] The organic group having at least one ring structure and having 3 to 40 carbon atoms represented by W is not particularly limited and may be either a group containing only a ring structure or a group formed by combining a ring structure and a chain structure. The ring structure may be any of a monocyclic structure, a polycyclic structure, or a combination thereof. In addition, the ring structure may be any of an alicyclic structure, an aromatic ring structure, a heterocyclic structure, or a combination thereof. In the case of a combination, it may be a structure in which a ring structure is bonded to a chain structure, or two or more ring structures may form a condensed ring structure or a bridged ring structure. The number of ring structures in the organic group is only required to be 1 or more, and may also be 2 or more. The divalent heteroatom-containing group may be present between carbon-carbon atoms forming the skeleton of the ring structure or the chain structure, and the hydrogen atom on the carbon atom of the ring structure or the chain structure may also be substituted with other substituents.

[0038] As the alicyclic structure, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be cited. As the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group can be cited. As the monocyclic saturated hydrocarbon group, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl are preferred. As the polycyclic cycloalkyl group, a bridged alicyclic hydrocarbon group such as norbornyl, adamantyl, tricyclodecyl, tetracyclododecyl, etc. is preferred. As the monocyclic unsaturated hydrocarbon group, monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl can be cited. As the polycyclic unsaturated hydrocarbon group, polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, tetracyclododecenyl can be cited. In addition, the so-called bridged alicyclic hydrocarbon group means a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms among the carbon atoms constituting the alicyclic ring are bonded through a bonding chain containing one or more carbon atoms.

[0039] As the aromatic ring structure, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms can be cited. As the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, for example, aryl groups such as phenyl, tolyl, xylyl, naphthyl, anthryl; aralkyl groups such as benzyl, phenethyl, naphthylmethyl, etc. can be cited.

[0040] As the heterocyclic structure, a group formed by removing one hydrogen atom from an aromatic heterocyclic structure and a group formed by removing one hydrogen atom from an alicyclic heterocyclic structure can be cited. An aromatic structure of a five-membered ring having aromaticity by introducing a heteroatom is also included in the heterocyclic structure. As the heteroatom, oxygen atom, nitrogen atom, sulfur atom, etc. can be cited.

[0041] As the aromatic heterocyclic structure, for example,

[0042] Aromatic heterocyclic structures containing an oxygen atom such as furan, pyran, benzofuran, benzopyran;

[0043] Aromatic heterocyclic structures containing a nitrogen atom such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, carbazole;

[0044] Aromatic heterocyclic structures containing a sulfur atom such as thiophene;

[0045] Aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, oxazine, etc.

[0046] As the alicyclic heterocyclic structure, for example,

[0047] Alicyclic heterocyclic structures containing an oxygen atom such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, dioxane;

[0048] Alicyclic heterocyclic structures containing a nitrogen atom such as aziridine, pyrrolidine, piperidine, piperazine;

[0049] Aliphatic heterocyclic structures containing sulfur atoms such as thietane, thiolane, and thiane;

[0050] Aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane;

[0051] Lactone structures, cyclic carbonate structures, and sultone structures, etc.

[0052] The heterocyclic structure contains a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal, or a combination thereof.

[0053] As the linear structure, a monovalent linear organic group having 1 to 30 carbon atoms can be exemplified. As the monovalent linear organic group having 1 to 30 carbon atoms, as long as it has a linear structure, it is not particularly limited. As the linear structure, a monovalent linear hydrocarbon group having 1 to 30 carbon atoms that can be either saturated or unsaturated, straight-chain or branched-chain, a group formed by substituting a part or all of the hydrogen atoms contained in the linear hydrocarbon group with a substituent, a group containing a divalent heteroatom-containing group between the carbon-carbon bonds of these groups, or a combination thereof, etc. can be exemplified.

[0054] As the monovalent linear hydrocarbon group having 1 to 30 carbon atoms, for example, a straight-chain or branched-chain saturated hydrocarbon group having 1 to 30 carbon atoms or a straight-chain or branched-chain unsaturated hydrocarbon group having 1 to 30 carbon atoms can be exemplified. As the straight-chain or branched-chain saturated hydrocarbon group having 1 to 30 carbon atoms, for example, alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, and isoheptyl can be exemplified. As the straight-chain or branched-chain unsaturated hydrocarbon group having 1 to 30 carbon atoms, for example, alkenyl groups such as vinyl, propenyl, and butenyl; alkynyl groups such as ethynyl, propynyl, and butynyl can be exemplified.

[0055] As the substituent that substitutes a part or all of the hydrogen atoms of the linear hydrocarbon group, for example, halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom; hydroxyl group; carboxyl group; cyano group; nitro group; amino group; aldehyde group; mercapto group; side oxygen group (=O), etc. can be exemplified.

[0056] As the divalent heteroatom-containing group in the group containing a divalent heteroatom-containing group between the carbon-carbon bonds of the linear hydrocarbon group, -CO-, -C(=O)O-, -CS-, -O-, -S-, -SO2-, -NR”- or a combination of two or more of these can be preferably used. R” is a hydrogen atom or a monovalent hydrocarbon group having 1 to 5 carbon atoms. When the linear hydrocarbon group has the divalent heteroatom-containing group, the number of the divalent heteroatom-containing groups is preferably one, two, or three, and more preferably one or two.

[0057] The bonding sites of the carboxyl group and the hydroxyl group bonded to W in the formula (1) are not particularly limited, and can be bonded to a certain position on the structure represented by W. Preferably, they are directly or indirectly bonded to the same or different ring structures respectively, more preferably directly bonded to the same or different ring structures respectively, and further preferably directly bonded to the same ring structure respectively, and at least one hydroxyl group is bonded to the carbon atom adjacent to the carbon atom to which the carboxyl group is bonded.

[0058] Regarding the manner in which the carboxyl group and the hydroxyl group are directly or indirectly bonded to the same ring structure, preferably, the partial structure “-W(OH) p (COOH) q ” in the formula (1) contains one or more groups selected from the group consisting of the groups represented by the following formulae (W-1) to (W-5).

[0059] [Chemical formula 3]

[0060]

[0061] (In the formula, s is an integer of 0 to 2, and t is an integer of 1 to 3; l, m, and n are each independently an integer of 1 to 6; X is a hydrogen atom, an organic group having 1 to 12 carbon atoms, a cyano group, a hydroxyl group, or a halogen atom; b is 1 to 10; when b is 2 or more, a plurality of Xs may be the same or different; R 1 、R 2 are the same as or different from each other and are a single bond or a divalent organic group)

[0062] In the formula (W-1), s is an integer of 0 to 2, preferably 0 or 1. In the formula (W-2), t is an integer of 1 to 3, preferably 1 or 2. In the formula (W-3), l, m, and n are each independently an integer of 1 to 6, preferably l is 2, m is 1, and n is 2.

[0063] Examples of the organic group having 1 to 12 carbon atoms as X in the formulae (W-1) to (W-5) include a hydrocarbon group having 1 to 12 carbon atoms and a monovalent organic group represented by -X 1 -Y-X 2 (wherein, X 1 is a single bond or a divalent hydrocarbon group having 1 to 11 carbon atoms, Y is -O-, -CO-, -COO-, -OCO-, -OCOO-, -NHCO-, or -CONH-, and X 2 is a monovalent hydrocarbon group having 1 to 12 carbon atoms).

[0064] Examples of the hydrocarbon group having 1 to 12 carbon atoms as X and X 2 include a monovalent linear hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, or a combination thereof, etc.

[0065] As the monovalent linear hydrocarbon group having 1 to 12 carbon atoms, the group corresponding to 1 to 12 carbon atoms in the monovalent linear hydrocarbon group having 1 to 30 carbon atoms in W of the formula (1) can be preferably used.

[0066] As the monovalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, the group corresponding to 3 to 12 carbon atoms in the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in W of the formula (1) can be preferably used.

[0067] As the monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, the group corresponding to 6 to 12 carbon atoms in the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in W of the formula (1) can be preferably used.

[0068] As X 1 For the divalent hydrocarbon group having 1 to 11 carbon atoms represented, a group formed by removing one hydrogen atom from the group corresponding to 1 to 11 carbon atoms among the groups listed from the hydrocarbon group having 1 to 12 carbon atoms can be preferably used.

[0069] As the halogen atom represented by X, for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom can be listed. Among these, a fluorine atom and an iodine atom are preferred.

[0070] b is an integer of 1 to 3, and preferably 1 or 2. When b is 2 or more, the plurality of Xs may be the same or different from each other.

[0071] As R 1 、R 2 For the divalent organic group represented, a divalent organic group having 1 to 30 carbon atoms can be listed. For example, a divalent hydrocarbon group having 1 to 30 carbon atoms, a group containing a divalent heteroatom-containing group between carbon-carbon bonds or at any terminal in the hydrocarbon group, a group formed by substituting a part or all of the hydrogen atoms of the group and the hydrocarbon group with a monovalent heteroatom-containing group, etc. can be listed.

[0072] As the divalent organic group having 1 to 30 carbon atoms, a group formed by removing one hydrogen atom from the monovalent linear hydrocarbon group having 1 to 30 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in W of the formula (1) can be listed. In addition, a group formed by removing two hydrogen atoms from the aromatic heterocyclic structure in W of the formula (1) and a group formed by removing two hydrogen atoms from the alicyclic heterocyclic structure can be listed.

[0073] As the divalent heteroatom-containing group, the divalent heteroatom-containing group in W of the formula (1) can be preferably used.

[0074] As the monovalent heteroatom-containing group, for example, halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, a hydrogen sulfide group (-SH), etc. can be listed.

[0075] Among these, as R 1 and R 2 , it is preferably a single bond, a divalent chain hydrocarbon group or a group containing a divalent heteroatom-containing group between carbon-carbon atoms of the divalent chain hydrocarbon group, and more preferably a single bond.

[0076] Regarding the manner in which the carboxyl group and the hydroxyl group are directly or indirectly bonded to different ring structures, it is preferably that the partial structure "-W(OH) p (COOH) q " in the formula (1) contains one or more groups selected from the group consisting of the groups represented by the following formulas (W-6) to (W-9), and

[0077] contains one or more groups selected from the group consisting of the groups represented by the following formulas (W-10) to (W-13).

[0078] [Chemical formula 4]

[0079]

[0080] s, t, l, m, n, X, b, R in the formulas (W-6) to (W-13) 1 and R 2 have the same meanings as s, t, l, m, n, X, b, R in the formulas (W-1) to (W-5). 1 and R 2

[0081] In addition, one or more groups selected from the group consisting of the groups represented by the formulas (W-6) to (W-9) and one or more groups selected from the group consisting of the groups represented by the formulas (W-10) to (W-13) may also be bonded via a divalent organic group.

[0082] As such a divalent organic group, for example, a divalent organic group represented by -X 1 -Y-X 1 - can be cited. X 1 , Y have the same meanings as X 1 , Y in the formulas (W-1) to (W-5). In addition, the two X 1 may be the same or different. Specifically, for example, -CH2OC(=O)-, -OC(=O)- can be preferably cited.

[0083] ​In the formula (1), L is a (r + 1)-valent linking group, r is 1 to 3, preferably 1 or 2. Regarding p and q, when r is 1, p and q are each 1 to 3, and when r is 2 to 3, multiple p's and q's are each 0 to 3. Among them, when r is 2 to 3, at least one of the multiple p's is 1 or more, and at least one of the multiple q's is 1 or more.

[0084] Examples of the (r + 1)-valent linking group represented by L include groups having one or more bonding groups selected from the group consisting of an ether bond, an amide bond, an ester bond, and an acetal bond.

[0085] L is preferably at least one structure selected from the structures represented by the following formulas (L-1) to (L-5).

[0086] [Chemical formula 5]

[0087]

[0088] (In formula (L-1), R 11 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms; R 12 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms; * is a bonding bond that bonds to W in the formula (1), and ** is a bonding bond that bonds to S of SO3 - in the formula (1))

[0089] [Chemical formula 6]

[0090]

[0091] (In formula (L-2), R 13 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms; R 14 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms; * is a bonding bond that bonds to W in the formula (1), and ** is a bonding bond that bonds to S of SO3 - in the formula (1))

[0092] [Chemical formula 7]

[0093]

[0094] (In formula (L-3), R 21 , R 22 are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms, and a is an integer of 1 to 3; * is a bonding bond that bonds to W in the formula (1), and ** is a bonding bond that bonds to S of SO3 - in the formula (1))

[0095] [Chemical formula 8]

[0096]

[0097] (In formula (L-4), Y 11 and Y 12 are each independently an oxygen atom or a sulfur atom; R 41 is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, or a -X 1 -Y-X 2 -represented monovalent organic group (wherein, X 1 is a single bond or a divalent hydrocarbon group having 1 to 11 carbon atoms, Y is -O-, -CO-, -COO-, -OCO-, -OCOO-, -NHCO- or -CONH-, and X 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms); R 42 is a single bond, or a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms; R 43 is a single bond or a divalent organic group; Q forms a monocyclic or condensed-ring cyclic (thio) acetal structure together with Y 11 , Y 12 and the carbon atom to which these are bonded; * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to the S of SO3 - in the formula (1))

[0098] [Chemical Formula 9]

[0099]

[0100] (In formula (L-5), Y 11 , Y 12 , R 42 , R 43 , Q have the same meanings as in the formula (L-4); R 44 is a single bond or a divalent organic group; * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to the S of SO3 - in the formula (1))

[0101] The divalent hydrocarbon groups having 1 to 12 carbon atoms represented by R 11 , R 12 , R 13 , R 14 , R 21 , R 22 in the formulas (L-1) to (L-3) are preferably groups formed by removing one hydrogen atom from the groups listed in the hydrocarbon groups having 1 to 12 carbon atoms in X of the formulas (W-1) to (W-5).

[0102] R in the formula (L-4)41 The monovalent hydrocarbon group having 1 to 10 carbon atoms represented may preferably be a group corresponding to 1 to 10 carbon atoms among the groups listed in the hydrocarbon group having 1 to 12 carbon atoms in X of the formulas (W-1) to (W-5).

[0103] Regarding -X having 1 to 12 carbon atoms in the formulas (L-4) and (L-5) 1 -Y-X 2 The monovalent organic group represented is the same in meaning as -X having 1 to 12 carbon atoms in the formulas (W-1) to (W-5) 1 -Y-X 2 The monovalent organic group represented has the same meaning.

[0104] R in the formulas (L-4) and (L-5) 42 The divalent hydrocarbon group having 1 to 10 carbon atoms represented may preferably be a group formed by removing one hydrogen atom from the group corresponding to 1 to 10 carbon atoms among the groups listed in the hydrocarbon group having 1 to 12 carbon atoms in X of the formulas (W-1) to (W-5).

[0105] R in the formulas (L-4) and (L-5) 43 、R 44 The divalent organic group represented may preferably be the divalent organic group in R of the formulas (W-1) to (W-5) 1 among them.

[0106] As a substituent for substituting part or all of the hydrogen atoms possessed by the hydrocarbon group, the substituents in W of the formula (1) may be mentioned.

[0107] L contains a ring structure, and the ring structure of L and the ring structure possessed by W may form a spiro ring structure. Specifically, for example, when W has a cyclohexane ring structure and L has the cyclic (thio)acetal structure represented by the formula (L-4), the following spiro ring structure is formed. Among them, this is an example of forming a spiro ring structure and is not limited thereto.

[0108] [Chemical formula 10]

[0109]

[0110] (In the formula, R 1 、R 2 、X, and b have the same meaning as R 1 、R 2 、X, and b in the formulas (W-1) to (W-4), R 42 has the same meaning as R 42 in the formula (L-4))

[0111] Regarding the onium salt compound (1), in order to fully function as a radiation-sensitive strong acid generator, it is preferable that fluorine or a fluorinated hydrocarbon group is bonded to the carbon atom adjacent to the sulfur atom of the sulfonate ion (SO3 - ).

[0112] Regarding specific examples of the anion of the onium salt compound (1) as a radiation-sensitive strong acid generator, although not limited, for example, the structures of the following formulas (1-1-1) to (1-1-36) can be cited.

[0113] [Chemical formula 11]

[0114]

[0115] [Chemical formula 12]

[0116]

[0117] [Chemical formula 13]

[0118]

[0119] [Chemical formula 14]

[0120]

[0121] [Chemical formula 15]

[0122]

[0123] In the formula (1), as the monovalent onium cation represented by M + , for example, radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi can be cited. As radiation-decomposable onium cations, for example, sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, etc. can be cited. Among them, sulfonium cations or iodonium cations are preferable. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0124] [Chemical formula 16]

[0125]

[0126] In the formula (X-1), R a1 , R a2 and R a3Each independently is a substituted or unsubstituted linear or branched alkyl, alkoxy or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxyl group, a halogen atom, -OSO2-R P , -SO2-R Q , -S-R T , -O-, -CO- or a combination thereof, or represents a ring structure formed by the combination of two or more of these groups. The ring structure may contain heteroatoms such as O or S between the carbon-carbon bonds forming the skeleton. R P , R Q and R T Each independently is a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. In R a1 ~R a3 and R P , R Q and R T When there are a plurality of them respectively, the plurality of R a1 ~R a3 and R P , R Q and R T may be the same or different respectively.

[0127] In the formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group, an alkoxyalkyloxy group, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. n k is 0 or 1. When n k is 0, k4 is an integer of 0 to 4, and when n k is 1, k4 is an integer of 0 to 7. When there are a plurality of R b1 , the plurality of R b1 may be the same or different, and in addition, the plurality of R b1 may also be represented as a ring structure formed by their combination. 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 of 0 to 4. When there are a plurality of R b2 , the plurality of R b2 may be the same or different, and in addition, the plurality of R b2It can also be a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, it contains S + The ring structure containing + may contain heteroatoms such as O or S between the carbon-carbon bonds forming the backbone.

[0128] In the 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.

[0129] In the 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, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. n k2 is 0 or 1. 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. When there are multiple R g1 , the multiple R g1 can be the same or different. Additionally, the multiple R g1 can also be a ring structure formed by combining with each other. R g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxyl group, a halogen atom, or a ring structure formed by combining these groups with each other. k11 and k12 are each independently an integer from 0 to 4. When R g2 and R g3 are each multiple, the multiple R g2 and R g3 can be the same or different from each other respectively.

[0130] In the formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups with each other. k6 and k7 are each independently an integer from 0 to 5. When R d1 and R d2 are each multiple, the multiple R d1 and R d2 can be the same or different from each other respectively.

[0131] In the formula (X-6), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0132] Specific examples of the radiation-sensitive onium cation are not limited, but for example, structures such as the following formulas (1-2-1) to (1-2-54) can be cited.

[0133] [Chemical formula 17]

[0134]

[0135] (In the formula, tBu represents tert-butyl and Me represents methyl)

[0136] [Chemical formula 18]

[0137]

[0138] [Chemical formula 19]

[0139]

[0140] The onium salt compound (1) as the radiation-sensitive strong acid generator can be obtained by appropriately combining the anion and the radiation-sensitive onium cation. Specific examples are not particularly limited, but for example, structures such as the following formulas (1-3-1) to (1-3-36) can be cited.

[0141] [Chemical formula 20]

[0142]

[0143] [Chemical formula 21]

[0144]

[0145] [Chemical formula 22]

[0146]

[0147] [Chemical formula 23]

[0148]

[0149] With respect to 100 parts by mass of the following-described polymer, the lower limit of the content of the onium salt compound (1) as a radiation-sensitive strong acid generator (in the case of containing a plurality of onium salt compounds (1), the total thereof) is preferably 0.1 part by mass, more preferably 0.5 part by mass, still more preferably 1 part by mass, and particularly preferably 3 parts by mass. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, still more preferably 35 parts by mass. The content of the onium salt compound (1) can be appropriately selected according to the type of the polymer used, exposure conditions, required sensitivity, etc. Thereby, when forming a resist pattern, excellent sensitivity, LWR, pattern circularity, development defect performance, EL, CDU, and pattern circularity can be exhibited.

[0150] The onium salt compound (1) as a radiation-sensitive strong acid generator and other radiation-sensitive strong acid generators (for example, the following onium salt compound (P1)) can also be used in combination. With respect to the total mass of the radiation-sensitive strong acid generators contained in the composition, the lower limit of the content of the onium salt compound (1) in the case of combined use is preferably 35% by mass, more preferably 40% by mass, still more preferably 45% by mass. In addition, the upper limit is preferably 75% by mass, more preferably 70% by mass, still more preferably 60% by mass. Thereby, when forming a resist pattern, excellent sensitivity, LWR, pattern rectangularity, EL, development defect performance, CDU, and pattern circularity can be exhibited.

[0151] (Synthesis method of onium salt compound (1))

[0152] As a synthesis method of the onium salt compound (1), the following representative process is shown.

[0153] [Chemical formula 24]

[0154]

[0155] In the said process, W, q, p, r, L, M + have the same meanings as those in the formula (1).

[0156] The bromine moiety of (a-1) is converted into a sulfonate by a dithionite and an oxidizing agent, and salt exchange is carried out by reacting with an onium cation halide salt corresponding to the onium cation (a bromide salt in the process), whereby the target onium salt compound (1) represented by the formula (a-2) can be synthesized. In addition, other than the above, the target onium salt compound (1) can also be synthesized according to the synthesis process described in the examples.

[0157] (Onium salt compound (1) as an acid diffusion control agent)

[0158] The onium salt compound (1) also functions as an acid diffusion control agent due to its structure. Examples of the anion of the onium salt compound (1) as an acid diffusion control agent include anions in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom bonded to the sulfur atom of SO3 as the anion of the onium salt compound (1) which is a radiation-sensitive strong acid generator. - An anion in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to the carbon atom bonded to the sulfur atom of SO3.

[0159] As the radiation-sensitive onium cation of the onium salt compound (1) as an acid diffusion control agent, a radiation-sensitive onium cation identical to the radiation-sensitive onium cation of the onium salt compound (1) which is a radiation-sensitive strong acid generator can be preferably cited.

[0160] The onium salt compound (1) as an acid diffusion control agent can be obtained by appropriately combining the anion and the radiation-sensitive onium cation. As a specific example, although not particularly limited, structures such as the following formulas (1-4-1) to (1-4-34) can be cited, for example.

[0161] [Chemical formula 25]

[0162]

[0163] [Chemical formula 26]

[0164]

[0165] [Chemical formula 27]

[0166]

[0167] [Chemical formula 28]

[0168]

[0169] With respect to 100 parts by mass of the polymer described later, the lower limit of the content of the onium salt compound (1) as an acid diffusion control agent (in the case of containing a plurality of onium salt compounds (1), it is the total thereof) is preferably 0.1 part by mass, more preferably 0.5 part by mass, still more preferably 1 part by mass, and particularly preferably 3 parts by mass. The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, still more preferably 20 parts by mass, and particularly preferably 10 parts by mass. The content of the onium salt compound (1) can be appropriately selected according to the type of the polymer used, the exposure conditions, or the required sensitivity, etc. Thereby, excellent sensitivity, LWR, pattern circularity, development defect performance, EL, CDU, and pattern circularity can be exhibited when forming a resist pattern.

[0170] Regardless of whether the onium salt compound (1) functions as a radiation-sensitive strong acid generator or an acid diffusion control agent, the lower limit of the content of the onium salt compound (1) is preferably 0.1 part by mass, more preferably 0.5 part by mass, still more preferably 1 part by mass, and particularly preferably 3 parts by mass. The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, and still more preferably 20 parts by mass. Thus, when forming a resist pattern, excellent sensitivity, LWR, pattern circularity, development defect performance, EL, CDU, and pattern circularity can be exhibited.

[0171] (Radiation-sensitive strong acid generator other than the onium salt compound (1))

[0172] In the radiation-sensitive composition, a radiation-sensitive strong acid generator other than the onium salt compound (1) that functions as a radiation-sensitive strong acid generator may be included.

[0173] As the radiation-sensitive strong acid generator, an onium salt compound (P1) represented by the following formula (P1) (excluding the compound corresponding to the onium salt compound (1)) can be exemplified.

[0174] [Chemical formula 29]

[0175]

[0176] (In formula (P1),

[0177] R 40 is a monovalent organic group having 3 to 40 carbon atoms and containing a ring structure

[0178] R f21 and R f22 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group; when there are a plurality of R f21 and R f22 in the case, the plurality of R f21 and R f22 are each the same or different;

[0179] n is an integer of 1 to 4;

[0180] Z2 + is a monovalent radiation-sensitive onium cation)

[0181] As the monovalent organic group having 3 to 40 carbon atoms and containing a ring structure represented by R 40 , a monovalent organic group in the organic group having 3 to 40 carbon atoms and having at least one ring structure represented by W of the formula (1) can be preferably used.

[0182] As R f21 and R f22Examples of the monovalent fluorinated hydrocarbon group represented include monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and the like.

[0183] Examples of the monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms include:

[0184] Fluorinated alkyl groups such as trifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, 2,2,3,3,3-pentafluoropropyl, 1,1,1,3,3,3-hexafluoropropyl, heptafluoropropyl, heptafluoroisopropyl, nonafluorobutyl, nonafluoroisobutyl, nonafluorotert-butyl, 2,2,3,3,4,4,5,5-octafluoropentyl, tridecafluorohexyl, 5,5,5-trifluoro-1,1-diethylpentyl;

[0185] Fluorinated alkenyl groups such as trifluorovinyl, pentafluoropropenyl;

[0186] Fluorinated alkynyl groups such as fluoroethynyl, trifluoropropynyl, etc.

[0187] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include:

[0188] Fluorinated cycloalkyl groups such as fluorocyclopentyl, difluorocyclopentyl, nonafluorocyclopentyl, fluorocyclohexyl, difluorocyclohexyl, undecafluorocyclohexylmethyl, fluoronorbornanyl, fluoroadamantyl, fluorobornyl, fluoroisobornyl, fluorotricyclodecyl;

[0189] Fluorinated cycloalkenyl groups such as fluorocyclopentenyl, nonafluorocyclohexenyl, etc.

[0190] As the fluorinated hydrocarbon group, a monovalent fluorinated linear hydrocarbon group having 1 to 8 carbon atoms is preferred, and a monovalent fluorinated straight-chain hydrocarbon group having 1 to 5 carbon atoms is more preferred.

[0191] Specific examples of the anion of the onium salt compound (P1) are not limited, but include, for example, the structures of the following formulas (2-1-1) to (2-1-32).

[0192] [Chemical formula 30]

[0193]

[0194] [Chemical formula 31]

[0195]

[0196] [Chemical formula 32]

[0197]

[0198] As a specific example of the radiation-sensitive onium cation of the onium salt compound (P1), although not limited, a structure exemplified as a specific example of the radiation-sensitive onium cation of the formula (1) can be preferably adopted.

[0199] As the onium salt compound (P1), a structure formed by arbitrarily combining the anion and the radiation-sensitive onium cation can be exemplified. As a specific example of the onium salt compound (P1), although not limited, for example, onium salt compounds represented by the following formulas (2-1) to (2-32) can be exemplified.

[0200] [Chemical formula 33]

[0201]

[0202] [Chemical formula 34]

[0203]

[0204] [Chemical formula 35]

[0205]

[0206] With respect to 100 parts by mass of the polymer described later, the lower limit of the content of the onium salt compound (P1) (in the case of containing a plurality of onium salt compounds (P1), it is the total thereof) is preferably 0 part by mass, more preferably 0.1 part by mass, still more preferably 0.5 part by mass, and particularly preferably 3 parts by mass. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, still more preferably 30 parts by mass, and particularly preferably 25 parts by mass. The content of the onium salt compound (P1) can be appropriately selected according to the type of the polymer used, the exposure conditions, or the required sensitivity, etc.

[0207] (Polymer)

[0208] The polymer is an aggregate of polymer chains containing a structural unit having an acid dissociable group (hereinafter, also referred to as "structural unit (I)") (hereinafter, the aggregate is also referred to as "base polymer"). The "acid dissociable group" is a group that substitutes the hydrogen atom of a carboxyl group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and dissociates by the action of an acid. The radiation-sensitive composition has excellent pattern formability due to the polymer having the structural unit (I).

[0209] The base polymer preferably contains, in addition to the structural unit (I), 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 also contain other structural units other than the structural unit (I) and the structural unit (II). Hereinafter, each structural unit will be described.

[0210] [Structural unit (I)]

[0211] The structural unit (I) is a structural unit containing an acid dissociable group. As the structural unit (I), as long as it contains an acid dissociable group, it is not particularly limited. For example, it may include: a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, a structural unit having an acetal bond, etc. From the viewpoint of improving the pattern forming property of the radiation-sensitive composition, it is preferably a structural unit represented by the following formula (2) (hereinafter, also referred to as "structural unit (I-1)").

[0212] [Chemical formula 36]

[0213]

[0214] In the formula (2), R 51 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 52 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. R 53 and R 54 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 R 53 and R 54 are combined with each other and together with the carbon atom to which they are bonded form a divalent alicyclic group having 3 to 20 carbon atoms. L 81 is a single bond or a divalent organic group.

[0215] As the R 51 , from the viewpoint of providing the copolymerizability of the monomer of the structural unit (I-1), it is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

[0216] As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 52 , for example, it may 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, etc.

[0217] As the linear hydrocarbon group having 1 to 10 carbon atoms represented by R 52 to R 54 , the group corresponding to 1 to 10 carbon atoms in the monovalent linear hydrocarbon group having 1 to 30 carbon atoms in W of the formula (1) can be preferably used.

[0218] As the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R 52 to R 54 , the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in W of the formula (1) can be preferably used.

[0219] As the R 52The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented may preferably be the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in W of the formula (1).

[0220] As the R 52 , it is preferably a linear or branched chain saturated hydrocarbon group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0221] The R 53 and R 54 The divalent alicyclic group having 3 to 20 carbon atoms formed by the chain hydrocarbon group or alicyclic hydrocarbon group represented binding to each other and together with the carbon atoms to which they are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom of the carbon ring of the alicyclic hydrocarbon of the carbon number forming the monocyclic or polycyclic. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. As the polycyclic hydrocarbon group, it may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may also be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. In addition, the so-called condensed alicyclic hydrocarbon group is a polycyclic alicyclic hydrocarbon group formed in such a form that multiple alicycles share a side (bond between adjacent two carbon atoms).

[0222] As the saturated hydrocarbon group in the monocyclic alicyclic hydrocarbon group, it is preferably cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, cyclooctanediyl, etc. As the unsaturated hydrocarbon group, it is preferably cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, cyclodecenediyl, etc. As the polycyclic alicyclic hydrocarbon group, it is preferably a bridged alicyclic saturated hydrocarbon group. For example, it is preferably bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, tricyclo[3.3.1.1 3,7 decane-2,2-diyl (adamantane-2,2-diyl), etc.

[0223] Among these, it is preferable that R 52 is an alkyl group having 1 to 4 carbon atoms, and the alicyclic structure formed by R 53 and R 54 binding to each other and together with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0224] As the substituent that substitutes for a part or all of the hydrogen atoms of the hydrocarbon group, the substituents in W of the formula (1) can be cited.

[0225] The divalent organic group in L 81 may preferably be the divalent organic group in R 1 in the formulae (W-1) to (W-5)

[0226] As the structural unit (I-1), for example, the structural units represented by the following formulas (3-1) to (3-9) (hereinafter, also referred to as "structural units (I-1-1) to structural units (I-1-9)") etc. can be cited.

[0227] [Chemical formula 37]

[0228]

[0229] In the above formulas (3-1) to (3-9), R 51 ~R 54 have the same meaning as in the above formula (2). i and j are each independently an integer of 1 to 4. k and l are 0 or 1.

[0230] As i and j, 1 is preferred. As R 52 , methyl, ethyl, isopropyl or cyclopentyl is preferred. As R 53 and R 54 , methyl or ethyl is preferred.

[0231] In the above formulas (3-1) to (3-9), X P1 is a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. P2 is an integer of 1 to 5. When P2 is 2 or more, the plurality of X P1 may be the same or different from each other. X P3 is a hydroxyl group, a halogen atom, a carboxyl group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group or an alkoxy group. a1 is an integer of 0 to 3. When a1 is 2 or more, the plurality of X P3 are the same or different from each other. a2 is an integer of 1 to 3.

[0232] The base polymer may contain one kind or contain two or more kinds of structural units (I) in combination.

[0233] With respect to all the structural units constituting the base polymer, the lower limit of the content ratio of the structural unit (I) (the total content ratio in the case of containing a plurality of kinds) is preferably 10 mol%, more preferably 20 mol%, still more preferably 30 mol%, and particularly preferably 35 mol%. In addition, the upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, still more preferably 60 mol%, and particularly preferably 55 mol%. By setting the content ratio of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive composition can be further improved.

[0234] [Structural unit (II)]

[0235] 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), the solubility of the base polymer in the developer can be adjusted. As a result, the radiation-sensitive composition can improve lithography performance such as analytical performance. In addition, the adhesion between the resist pattern formed from the base polymer and the substrate can be improved.

[0236] Examples of the structural unit (II) include structural units represented by the following formulas (T-1) to (T-11).

[0237] [Chemical formula 38]

[0238]

[0239] In the formulas, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R L2 to 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 hydroxyl group, a hydroxymethyl group, or a dimethylamino group. R L4 and R L5 may also be a divalent alicyclic group having 3 to 8 carbon atoms formed by bonding to each other and together with the carbon atom to which they are bonded. 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.

[0240] Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by bonding R L4 and R L5 to each other and together with the carbon atom to which they are bonded include groups having 3 to 8 carbon atoms among the divalent alicyclic groups having 3 to 20 carbon atoms formed by bonding the chain hydrocarbon group or alicyclic hydrocarbon group represented by R 53 and R 54 in the formula (2) to each other and together with the carbon atom to which they are bonded. One or more hydrogen atoms on the alicyclic group may also be substituted with a hydroxyl group.

[0241] Examples of the divalent linking group represented by 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 formed by combining one or more of these hydrocarbon groups with at least one group selected from -CO-, -O-, -NH-, and -S-.

[0242] Among these, as the structural unit (II), a structural unit containing a lactone structure is preferred, a structural unit containing a norbornane lactone structure is more preferred, and a structural unit derived from a (meth)acrylate norbornane lactone group ester is still more preferred.

[0243] With respect to all the structural units constituting the base polymer, the lower limit of the content ratio of the structural unit (II) is preferably 15 mol%, more preferably 20 mol%, and still more preferably 25 mol%. In addition, the upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and still more preferably 65 mol%. By setting the content ratio of the structural unit (II) within the above range, the radiation-sensitive composition can further improve lithography performance such as analyticity and the adhesion between the formed resist pattern and the substrate.

[0244] [Structural unit (III)]

[0245] In addition to having the structural unit (I) and the structural unit (II), the base polymer optionally has other structural units. Examples of the other structural units include a structural unit (III) containing a polar group (excluding the structural unit equivalent to the structural unit (II)). By further having the structural unit (III), the solubility of the base polymer in the developer can be adjusted, and as a result, the lithography performance such as analyticity of the radiation-sensitive composition can be improved. Examples of the polar group include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxyl group and a carboxyl group are preferred, and a hydroxyl group is more preferred.

[0246] Examples of the structural unit (III) include structural units represented by the following formulae.

[0247] [Chemical formula 39]

[0248]

[0249] In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0250] When the base polymer contains the structural unit (III) having a polar group, with respect to all the structural units constituting the base polymer, the lower limit of the content ratio of the structural unit (III) is preferably 2 mol%, more preferably 5 mol%, and still more preferably 8 mol%. In addition, the upper limit of the content ratio is preferably 40 mol%, more preferably 30 mol%, and still more preferably 25 mol%. By setting the content ratio of the structural unit (III) within the above range, the lithography performance such as analyticity of the radiation-sensitive composition can be further improved.

[0251] [Structural unit (IV)]

[0252] As other structural units, in addition to the structural unit (III) having a polar group, the base polymer may also optionally have a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both will also be collectively referred to as "structural unit (IV)"). The structural unit (IV) contributes to the improvement of etching resistance and the improvement of the difference in developer solubility (dissolution contrast) between the exposed portion and the unexposed portion. In particular, it can be preferably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less, such as electron beam or EUV. In such a case, the polymer preferably has both the structural unit (IV) and the structural unit (I).

[0253] The structural unit derived from hydroxystyrene is represented, for example, by the following formulas (4-1) to (4-2), etc., and the structural unit having a phenolic hydroxyl group is represented, for example, by the following formulas (4-3) to (4-4), etc.

[0254] [Chemical formula 40]

[0255]

[0256] In the above formulas (4-1) to (4-4), R 61 are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y is a halogen atom, a trifluoromethyl group, a cyano group, an alkyl or alkoxy group having 1 to 6 carbon atoms, or an acyl group, acyloxy group or alkoxycarbonyl group having 2 to 7 carbon atoms. In the case where there are a plurality of Ys, the plurality of Ys may be the same or different from each other. t is an integer from 0 to 4.

[0257] In the case of obtaining the structural unit (IV), it is preferable to carry out polymerization in a state where the phenolic hydroxyl group is protected by a protecting group such as an alkali dissociable group (e.g., acyl group) during polymerization, and then carry out hydrolysis and deprotection to obtain the structural unit (IV).

[0258] In the case of a polymer for exposure with radiation having a wavelength of 50 nm or less, the lower limit of the content ratio of the structural unit (IV) is preferably 10 mol%, more preferably 20 mol%, relative to all the structural units constituting the polymer. In addition, the upper limit of the content ratio is preferably 70 mol%, more preferably 60 mol%.

[0259] [Other structural units]

[0260] The base polymer may also contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the above-listed structural units.

[0261] [Chemical formula 41]

[0262]

[0263] (In the above formula (6), R1α 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)

[0264] In the formula (6) above, as R 2α The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by can preferably be the R in the formula (1) 1 and R 2 among the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0265] When the base polymer contains the structural unit having an alicyclic structure, the lower limit of the content ratio of the structural unit having an alicyclic structure is preferably 2 mol%, more preferably 5 mol%, and still more preferably 8 mol% with respect to all the structural units constituting the base polymer. In addition, the upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%, and still more preferably 15 mol%.

[0266] (Synthesis method of base polymer)

[0267] The base polymer can be synthesized, for example, by polymerizing monomers providing each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0268] 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), 2,2'-azobisisobutyric acid dimethyl ester; peroxide-based radical initiators such as benzoyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc. Among these, AIBN and 2,2'-azobisisobutyric acid dimethyl ester are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0269] Examples of the solvent used in the polymerization include:

[0270] alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane;

[0271] cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;

[0272] aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;

[0273] Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene;

[0274] Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, and methyl propionate;

[0275] Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone;

[0276] Lactones such as γ-butyrolactone;

[0277] Polyol partial ether carboxylic acid esters such as propylene glycol monomethyl ether acetate;

[0278] Ethers such as tetrahydrofuran, propylene glycol monomethyl ether, dimethoxyethanes, and diethoxyethanes;

[0279] Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-methoxy-2-propanol, and 4-methyl-2-pentanol. These solvents used in the polymerization can be used alone or in combination of two or more.

[0280] As the reaction temperature in the polymerization, it is usually 40°C to 150°C, preferably 50°C to 120°C. As the reaction time, it is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0281] The molecular weight of the base polymer is not particularly limited. As the lower limit of the polystyrene-equivalent weight average molecular weight (Mw) obtained by gel permeation chromatography (GPC), it is preferably 2,000, more preferably 3,000, further preferably 4,000, and particularly preferably 4,500. As the upper limit of Mw, it is preferably 30,000, more preferably 20,000, further preferably 12,000, and particularly preferably 10,000. By setting the Mw of the base polymer within the above range, good heat resistance and developability can be imparted to the obtained resist film.

[0282] The ratio (Mw / Mn) of the Mw of the base polymer to the polystyrene-equivalent number average molecular weight (Mn) obtained by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, further preferably 1 or more and 2 or less.

[0283] The Mw and Mn of the polymers in this specification are values measured by gel permeation chromatography (GPC) under the following conditions.

[0284] GPC columns: 2 pieces of G2000HXL, 1 piece of G3000HXL, 1 piece of G4000HXL (manufactured by Tosoh above)

[0285] Column temperature: 40 °C

[0286] Dissolution solvent: Tetrahydrofuran

[0287] Flow rate: 1.0 mL / min

[0288] Sample concentration: 1.0 mass%

[0289] Sample injection volume: 100 μL

[0290] Detector: Differential refractometer

[0291] Standard substance: Monodisperse polystyrene

[0292] The content ratio of the base polymer is preferably 60 mass% or more, more preferably 65 mass% or more, and still more preferably 70 mass% or more, relative to the total solid content of the radiation-sensitive composition.

[0293] (Other polymers)

[0294] The radiation-sensitive composition of the present embodiment may also contain a polymer having a higher mass content of fluorine atoms than the base polymer (hereinafter, also referred to as "high-fluorine-content polymer") as other polymers. When the radiation-sensitive composition contains a high-fluorine-content polymer, it can be preferentially present in the surface layer of the resist film relative to the base polymer. As a result, the water repellency of the surface of the resist film during immersion lithography can be improved, or surface modification of the resist film or control of the distribution of the film composition during EUV lithography can be achieved.

[0295] As the high-fluorine-content polymer, it is preferably, for example, a polymer having a structural unit represented by the following formula (5) (hereinafter, also referred to as "structural unit (V)"), and may also have structural unit (I) or structural unit (III) in the base polymer as needed.

[0296] [Chemical formula 42]

[0297]

[0298] In the formula (5), R 73 is a hydrogen atom, a methyl group, or a trifluoromethyl group. G L is a single bond, an alkanediyl group having 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, -OCO-, -SO2ONH-, -CONH-, -OCONH-, or a combination thereof. R 74 is a monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0299] As the R 73, from the viewpoint of the copolymerizability of the monomer providing the structural unit (V), it is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

[0300] As the G L , from the viewpoint of the copolymerizability of the monomer providing the structural unit (V), it is preferably a combination of at least one of a single bond, -COO-, -COO- and -OCO- and an alkanediyl group having 1 to 5 carbon atoms, more preferably -COO-.

[0301] As the R 74 The monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by can be exemplified by those in which part or all of the hydrogen atoms of a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0302] As the R 74 The monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by can be exemplified by those in which part or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms.

[0303] As the R 74 , it is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and further preferably 2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl, 1,1,1,3,3,3-hexafluoropropyl and 5,5,5-trifluoro-1,1-diethylpentyl.

[0304] When the high-fluorine content polymer has the structural unit (V), the lower limit of the content ratio of the structural unit (V) is preferably 40 mol%, more preferably 50 mol%, and further preferably 55 mol% with respect to all the structural units constituting the high-fluorine content polymer. In addition, the upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, and further preferably 70 mol%. 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 polymer can be adjusted more moderately, and the preferential existence 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.

[0305] The high-fluorine content polymer may also have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter, also referred to as structural unit (VI)) together with or instead of the structural unit (V). By the high-fluorine content polymer having the structural unit (f-2), the solubility in an alkaline developer can be improved, and the generation of development defects can be suppressed.

[0306] [Chemical formula 43]

[0307]

[0308] The structural unit (VI) is roughly divided into two cases: the case having (x) a base-soluble group and the case having (y) a group that dissociates by the action of a base and has increased solubility in an alkaline developer (hereinafter, also simply referred to as "base-dissociable group"). (x) and (y) are common to both. In the 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, an (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, a structure in which an oxygen atom, a sulfur atom, -NR E -, a carbonyl group, -COO-, -OCO-, or -CONH- is bonded to the terminal on the R dd side of the hydrocarbon group, or a structure in which a part of the hydrogen atoms of the hydrocarbon group is substituted with an organic group having a heteroatom. R dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0309] When the structural unit (VI) has (x) a base-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-*, or -SO2O-*. * represents the bonding position 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 on 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, multiple R E , W 1 , A 1 , and R F can be the same or different respectively. By the structural unit (VI) having (x) a base-soluble group, the affinity for an alkaline developer can be improved, and development defects can be suppressed. As the structural unit (VI) having (x) a base-soluble group, the case where A 1 is an oxygen atom and W 1 is 1,1,1,3,3,3-hexafluoro-2,2-methanediyl is particularly preferred.

[0310] When the structural unit (VI) has (y) a base-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-*, -OCO-*, or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * represents the bonding position to R FPart of W 1 Is a single bond or a divalent fluorinated hydrocarbon group with 1 to 20 carbon atoms. R E Is a single bond or a divalent organic group with 1 to 20 carbon atoms. In A 1 When it is -COO-*, -OCO-*, or -SO2O-*, W 1 Or R F Has a fluorine atom on the carbon atom bonded to A 1 Or the carbon atom adjacent to it. In A 1 When it is an oxygen atom, W 1 、R E Is a single bond, R D Is a structure in which a carbonyl group is bonded to the end on the R E Side of a hydrocarbon group with 1 to 20 carbon atoms, R F Is an organic group having a fluorine atom. When s is 2 or 3, multiple R E 、W 1 、A 1 And R F Can be the same or different respectively. By having the structural unit (VI) have a (y) base dissociable group, in the alkali developing process, the surface of the resist film changes from hydrophobic to hydrophilic. As a result, the affinity for the developer can be greatly improved, and development defects can be more effectively suppressed. As the structural unit (VI) having a (y) base dissociable group, it is particularly preferable that A 1 Is -COO-* and R F Or W 1 Or both of these have a fluorine atom.

[0311] As R C , from the viewpoints of copolymerizability of the monomer of the structural unit (VI), etc., it is preferably a hydrogen atom and a methyl group, and more preferably a methyl group.

[0312] In the case where R E Is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and still more preferably a group having a norbornane lactone structure.

[0313] When the high-fluorine content polymer has the structural unit (VI), the lower limit of the content ratio of the structural unit (VI) is preferably 40 mol%, more preferably 50 mol%, and still more preferably 55 mol% with respect to all the structural units constituting the high-fluorine content polymer. In addition, the upper limit of the content ratio is preferably 95 mol%, more preferably 90 mol%, and still more preferably 85 mol%. By setting the content ratio of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved, and development defects can be suppressed.

[0314] [Other structural units]

[0315] The high fluorine content polymer may also contain the structural unit (I) or the structural unit (III) in the base polymer and the structural unit having an alicyclic structure represented by the formula (6) as structural units other than the listed structural units.

[0316] When the high fluorine content polymer contains the structural unit (I) or the structural unit (III), the content ratio of each structural unit in the high fluorine content polymer may preferably adopt the content ratio described for the base polymer.

[0317] When the high fluorine content polymer contains the structural unit having an alicyclic structure, with respect to all the structural units constituting the high fluorine content polymer, the lower limit of the content ratio of the structural unit having an alicyclic structure is preferably 10 mol%, more preferably 20 mol%, and still more preferably 30 mol%. In addition, the upper limit of the content ratio is preferably 60 mol%, more preferably 50 mol%, and still more preferably 45 mol%.

[0318] The lower limit of the Mw of the high fluorine content polymer is preferably 2,000, more preferably 3,000, still more preferably 4,000, and particularly preferably 5,000. In addition, the upper limit of the Mw is preferably 30,000, more preferably 20,000, still more preferably 10,000, and particularly preferably 8,000.

[0319] The lower limit of the Mw / Mn of the high fluorine content polymer is usually 1, and more preferably 1.1. In addition, the upper limit of the Mw / Mn is usually 5, preferably 3, and more preferably 2.

[0320] When the radiation-sensitive composition contains a high fluorine content polymer, with respect to 100 parts by mass of the base polymer, the content of the high fluorine content polymer is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, still more preferably 1.5 part by mass or more, and particularly preferably 2 parts by mass or more. In addition, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less, and particularly preferably 6 parts by mass or less.

[0321] By setting the content of the high fluorine content polymer within the above range, the high fluorine content polymer can be more effectively biased to exist in the surface layer of the resist film. As a result, the water repellency of the surface of the resist film during immersion exposure can be further improved. The radiation-sensitive composition may contain one or more high fluorine content polymers.

[0322] (Synthesis method of high fluorine content polymer)

[0323] The high fluorine content polymer can be synthesized by the same method as the synthesis method of the base polymer.

[0324] (An acid diffusion control agent other than the onium salt compound (1) as an acid diffusion control agent)

[0325] The radiation-sensitive composition may also contain, if necessary, an acid diffusion control agent other than the onium salt compound (1) as an acid diffusion control agent. The acid diffusion control agent has the following effects: controlling the diffusion phenomenon of the acid generated from the onium salt compound (1) or other radiation-sensitive strong acid generators through exposure in the resist film, and suppressing the undesirable chemical reactions in the unexposed portion. In addition, the storage stability of the obtained radiation-sensitive composition is improved. Furthermore, the resolution of the resist pattern is further improved, and the line width variation of the resist pattern caused by the variation in the standing time from exposure to development processing can be suppressed, thereby obtaining a radiation-sensitive composition with excellent process stability.

[0326] Examples of the acid diffusion control agent include: a compound represented by the following formula (7) (hereinafter, also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter, also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter, also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, a nitrogen-containing heterocyclic compound, and the like.

[0327] [Chemical formula 44]

[0328]

[0329] In the formula (7), R 22 , R 23 and R 24 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0330] Examples of the nitrogen-containing compound (I) include: monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline and 2,6-di-isopropyl aniline, and the like.

[0331] Examples of the nitrogen-containing compound (II) include: ethylenediamine, N,N,N',N'-tetramethylethylenediamine, and the like.

[0332] Examples of the nitrogen-containing compound (III) include: polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethyl acrylamide, and the like.

[0333] Examples of the amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, etc.

[0334] Examples of the urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea, etc.

[0335] Examples of the nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecanecarbonyloxyethyl) morpholine; pyrazine, pyrazole, etc.

[0336] In addition, as the nitrogen-containing organic compound, a compound having an acid dissociable group can also be used. Examples of such a nitrogen-containing organic compound having an acid dissociable group include N-tert-butoxycarbonylpiperidine, N-tert-butoxycarbonylimidazole, N-tert-butoxycarbonylbenzimidazole, N-tert-butoxycarbonyl-2-phenylbenzimidazole, N-tert-amyloxycarbonyl-2-phenylbenzimidazole, N-(tert-butoxycarbonyl) di-n-octylamine, N-(tert-butoxycarbonyl) diethanolamine, N-(tert-butoxycarbonyl) dicyclohexylamine, N-(tert-butoxycarbonyl) diphenylamine, N-tert-butoxycarbonyl-4-hydroxypiperidine, N-tert-butoxycarbonyl-4-acetoxypiperidine, N-tert-amyloxycarbonyl-4-hydroxypiperidine, etc.

[0337] In addition, as the acid diffusion control agent, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can also be preferably used. The acid generated by the radiation-sensitive weak acid generator is a weak acid that does not induce the dissociation of the acid dissociable group under the conditions for dissociating the acid dissociable group in the polymer. In addition, in the present specification, the "dissociation" of the acid dissociable group means dissociation during baking after exposure at 110 °C for 60 seconds.

[0338] Examples of the radiation-sensitive weak acid generator include onium salt compounds that decompose upon exposure and lose acid diffusion control properties. Examples of the radiation-sensitive weak acid generator include sulfonium salt compounds represented by the following formula (8-1), iodonium salt compounds represented by the following formula (8-2), ammonium salt compounds represented by the following formula (8-5), etc. In addition, compounds containing a sulfonium cation and an anion in the same molecule represented by the following formula (8-3) or compounds containing an iodonium cation and an anion in the same molecule represented by the following formula (8-4) can be cited. Among them, compounds equivalent to the onium salt compound (1) as the acid diffusion control agent are not included.

[0339] [Chemical formula 45]

[0340]

[0341] In the formulas (8-1) to (8-5), J + is a sulfonium cation, and U + is an onium cation, and D + is an ammonium cation. As the sulfonium cation represented by J + , the sulfonium cations represented by the formulas (X-1) to (X-4) can be cited. As the onium cation represented by U + , the onium cations represented by the formulas (X-5) to (X-6) can be cited. As the ammonium cation represented by D + , it is preferably represented by N + -(R 50 )4. A plurality of R 50 are each independently a hydrogen atom or a monovalent hydrocarbon group. As the monovalent hydrocarbon group, the monovalent hydrocarbon group in the formula (1) can be preferably used.

[0342] E - , Q - , and V - are each independently an anion represented by OH - , R α -COO - , R α -SO3 - . R α is a single bond or a monovalent organic group having 1 to 30 carbon atoms (wherein, when the anion is represented by R α -SO3 - , a fluorine atom or a fluorinated hydrocarbon group is not bonded to the carbon atom bonded to the sulfur atom in R α ). As the organic group, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between carbon-carbon or at the end of the carbon chain of the hydrocarbon group, a group obtained by substituting a part or all of the hydrogen atoms of the hydrocarbon group with a monovalent heteroatom-containing group, or a combination thereof can be cited.

[0343] As the monovalent hydrocarbon group having 1 to 20 carbon atoms, the monovalent hydrocarbon group in the formula (1) can be preferably used.

[0344] As the heteroatom constituting the divalent or monovalent heteroatom-containing group, for example, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a silicon atom, a halogen atom, etc. can be cited. As the halogen atom, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom can be cited.

[0345] As the divalent heteroatom-containing group, the divalent heteroatom-containing group in the formula (1) can be preferably used.

[0346] As a monovalent heteroatom-containing group, for example, the following can be mentioned: hydroxyl group, hydrogen sulfide group, cyano group, nitro group, halogen atom, etc.

[0347] As the onium salt compound, for example, the compounds represented by the following formula can be mentioned, etc.

[0348] [Chemical formula 46]

[0349]

[0350] [Chemical formula 47]

[0351]

[0352] As the radiation-sensitive weak acid generator, among these, sulfonium salts are preferred, triarylsulfonium salts are more preferred, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are even more preferred.

[0353] With respect to 100 parts by mass of the polymer, the lower limit of the content of the acid diffusion control agent other than the onium salt compound (1) as the acid diffusion control agent is preferably 0.5 part by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass. In addition, the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

[0354] By setting the content of the acid diffusion control agent within the above range, the lithography performance of the radiation-sensitive composition can be further improved. The radiation-sensitive composition may also contain one or more acid diffusion control agents.

[0355] (Solvent)

[0356] The radiation-sensitive composition of the present embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the compound (1), the polymer, and the radiation-sensitive acid generator contained as needed.

[0357] As the solvent, for example, the following can be mentioned: alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, etc.

[0358] As the alcohol solvent, for example, the following can be mentioned:

[0359] Monohydric alcohol solvents having 1 to 18 carbon atoms such as isopropyl alcohol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, diacetone alcohol;

[0360] Polyhydric alcohol solvents having 2 to 18 carbon atoms such as ethylene glycol, 1,2-propanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;

[0361] A polyol partial ether solvent obtained by etherifying a part of the hydroxyl groups of the polyol solvent, etc.

[0362] Examples of the ether solvent include:

[0363] Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether;

[0364] Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;

[0365] Ether solvents containing an aromatic ring such as diphenyl ether and anisole (methyl phenyl ether);

[0366] A polyol ether solvent obtained by etherifying the hydroxyl groups of the polyol solvent, etc.

[0367] Examples of the ketone solvent include: chain ketone solvents such as acetone, butanone, and methyl-isobutyl ketone;

[0368] Cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone;

[0369] 2,4-Pentanedione, acetonylacetone, acetophenone, etc.

[0370] Examples of the amide solvent include: cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone;

[0371] Chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropanamide, etc.

[0372] Examples of the ester solvent include:

[0373] Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;

[0374] Polyol partial ether acetate solvents such as diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate;

[0375] Lactone solvents such as γ-butyrolactone and valerolactone;

[0376] Carbonate ester solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate;

[0377] Polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriethylene glycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0378] Examples of the hydrocarbon solvent include:

[0379] Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane;

[0380] Aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-amylnaphthalene.

[0381] Among these, ester solvents and ether solvents are preferred, polyol partial ether acetate solvents, lactone solvents, monocarboxylic acid ester solvents, and ketone solvents are more preferred, and propylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl lactate, cyclohexanone, and propylene glycol monomethyl ether are even more preferred. The radiation-sensitive composition may contain one or more than two solvents.

[0382] (Other optional components)

[0383] In addition to the above components, the radiation-sensitive composition may also contain other optional components. Examples of the other optional components include crosslinking agents, bias presence promoters, surfactants, compounds containing an alicyclic skeleton, sensitizers, etc. These other optional components may be used alone or in combination of two or more.

[0384] <Preparation method of the radiation-sensitive composition>

[0385] The radiation-sensitive composition can be prepared, for example, by mixing an onium salt compound (1), a polymer, a high-fluorine content polymer as needed, and a solvent in a specified ratio. The radiation-sensitive composition is preferably filtered, for example, using a filter with a pore size of about 0.05 μm to 0.40 μm after mixing. As the solid content concentration of the radiation-sensitive composition, it 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.

[0386] <Pattern formation method>

[0387] A pattern formation method according to an embodiment of the present invention includes:

[0388] Step (1) (hereinafter, also referred to as "resist film formation step"), forming a resist film by directly or indirectly coating the radiation-sensitive composition on a substrate;

[0389] Step (2) (hereinafter, also referred to as "exposure step"), exposing the resist film; and

[0390] Step (3) (hereinafter, also referred to as "development step"), developing the exposed resist film.

[0391] According to the resist pattern forming method, since the radiation-sensitive composition capable of forming a resist film excellent in sensitivity, LWR, DOF performance, pattern rectangularity, EL, CDU, and pattern circularity in the exposure process is used, a high-quality resist pattern can be formed. Hereinafter, each process will be described.

[0392] [Resist Film Formation Process]

[0393] In this process (the process (1)), a resist film is formed using the radiation-sensitive composition. As the substrate for forming the resist film, for example, substrates known in the past such as silicon wafers, silicon dioxide, and wafers coated with aluminum can be cited. In addition, an organic or inorganic antireflection film disclosed in, for example, Japanese Patent Publication No. 6-12452 or Japanese Patent Laid-Open No. 59-93448 can be formed on the substrate. As the coating method, for example, spin coating, casting coating, roll coating, etc. can be cited. After coating, prebaking (PB) may be performed as needed to volatilize the solvent in the coating film. As the PB temperature, it is usually 60°C to 150°C, preferably 80°C to 140°C. As the PB time, it is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0394] As the lower limit of the film thickness of the formed resist film, it is preferably 10 nm, more preferably 15 nm, and still more preferably 20 nm. As the upper limit of the film thickness, it is preferably 500 nm, more preferably 400 nm, and still more preferably 300 nm. Among them, for a thick resist film, when exposure using ArF excimer laser light is performed in the subsequent exposure process, the lower limit of the film thickness can be 100 nm, 150 nm, or 200 nm.

[0395] In the case of immersion exposure, regardless of the presence or absence of a water-repellent polymer additive such as the high-fluorine content polymer in the radiation-sensitive composition, for the purpose of avoiding direct contact between the immersion liquid and the resist film, an immersion protective film insoluble in the immersion liquid may be provided on the formed resist film. As the immersion protective film, either a solvent-strippable protective film (for example, refer to Japanese Patent Laid-Open No. 2006-227632) that is peeled off with a solvent before the development process or a developer-strippable protective film (for example, refer to WO2005-069076, WO2006-035790) that is peeled off simultaneously with the development in the development process can be used. Among them, from the viewpoint of production volume, it is preferable to use a developer-strippable immersion protective film.

[0396] In addition, when performing an exposure process as the next process using radiation with a wavelength of less than 50 nm, it is preferable to use a polymer having the structural unit (I) and the structural unit (IV) as the base polymer in the composition.

[0397] [Exposure process]

[0398] In this process (the process (2)), radiation is irradiated onto the resist film formed in the resist film formation process in the process (1) through a photomask (optionally via a liquid immersion liquid such as water) for exposure. As the radiation used in the exposure, depending on the line width of the target pattern, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and γ-rays; charged particle beams such as electron beams and α-rays can be cited. Among these, far ultraviolet light, electron beams, and EUV are preferable, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferable. Furthermore, electron beams and EUV with a wavelength of less than 50 nm, which are positioned as the next-generation exposure technology, are even more preferable.

[0399] When performing exposure by liquid immersion exposure, as the liquid immersion liquid used, for example, water, fluorine-based inert liquids, etc. can be cited. The liquid immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible to suppress deformation of the optical image projected onto the film to a minimum. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), based on the above viewpoints, in terms of ease of acquisition, ease of operation, etc., it is preferable to use water. When using water, an additive that reduces the surface tension of water and increases the interfacial activity can be added in a slightly proportion. The additive is preferably one that does not dissolve the resist film on the wafer and has a negligible impact on the optical coating on the lower surface of the lens. As the water used, distilled water is preferable.

[0400] It is preferable to perform post-exposure bake (PEB) after the exposure. In the exposed portion of the resist film, the acid generated from the radiation-sensitive acid generator through exposure is used to promote the dissociation of the acid-dissociable groups possessed by polymers and the like. Through the PEB, a difference in solubility in the developer is generated between the exposed portion and the unexposed portion. As the PEB temperature, it is usually 50°C to 180°C, preferably 80°C to 130°C. As the PEB time, it is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0401] [Development process]

[0402] In this step (the step (3)), the resist film exposed in the step (2), i.e., the exposure step, is developed. Thus, a prescribed resist pattern can be formed. Generally, after development, it is washed with a rinsing liquid such as water or alcohol and dried.

[0403] As the developer used in the development, in the case of alkali development, for example, an alkaline aqueous solution in which at least one of alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethyl ammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene, etc. is dissolved can be cited. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass% TMAH aqueous solution is more preferred.

[0404] In addition, in the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents can be cited. As the organic solvent, for example, one or more of the solvents cited as the solvent of the radiation-sensitive composition can be cited. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As the ether solvent, a glycol ether solvent is preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As the ester solvent, an acetate solvent is preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, a chain ketone is preferred, and 2-heptanone is more preferred. As the content of the organic solvent in the developer, 80 mass% or more is preferred, 90 mass% or more is more preferred, 95 mass% or more is further preferred, and 99 mass% or more is particularly preferred. As components other than the organic solvent in the developer, for example, water, silicone oil, etc. can be cited.

[0405] As described above, as the developer, either an alkaline developer or an organic solvent developer can be used. It can be appropriately selected according to the difference between the target positive pattern and negative pattern.

[0406] As the development method, for example, a method of immersing the substrate in a tank filled with the developer for a fixed time (immersion method); a method of developing by stacking the developer on the substrate surface using surface tension and allowing it to stand for a fixed time (puddle method); a method of spraying the developer on the substrate surface (spray method); a method of continuously coating the developer on a substrate rotating at a fixed speed while scanning the developer coating nozzle at a fixed speed (dynamic dispense method), etc. can be cited.

[0407] <Radiation-sensitive acid generator>

[0408] The radiation-sensitive acid generator of this embodiment is represented by the following formula (1).

[0409] [Chemical formula 48]

[0410]

[0411] (In formula (1), W is an organic group having at least one ring structure and having 3 to 40 carbon atoms; L is an (r + 1)-valent linking group, and r is an integer of 1 to 3; regarding p and q, when r is 1, both p and q are integers of 1 to 3, and when r is 2 to 3, a plurality of p's and q's are respectively integers of 0 to 3; wherein, when r is 2 to 3, at least one of the plurality of p's is 1 or more, and at least one of the plurality of q's is 1 or more; M + is a monovalent onium cation)

[0412] As the onium salt compound represented by the formula (1), the onium salt compound (1) in the radiation-sensitive composition can be preferably used.

[0413] Examples

[0414] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The following shows the measurement methods of various physical property values.

[0415] [Weight average molecular weight (Mw) and number average molecular weight (Mn)]

[0416] The Mw and Mn of the polymer are measured under the above conditions. In addition, the dispersity (Mw / Mn) is calculated based on the measurement results of Mw and Mn.

[0417] 13 C-Nuclear Magnetic Resonance 13 C-Nuclear Magnetic Resonance, 13 C-NMR) analysis]

[0418] For the 13 C-NMR analysis of the polymer, a nuclear magnetic resonance apparatus ("JNM-Delta400" manufactured by JEOL Ltd.) is used.

[0419] <Synthesis of polymer>

[0420] The monomers used in the synthesis of each polymer in each example and each comparative example are shown below. In addition, in the following synthesis examples, unless otherwise specified, parts by mass refer to values when the total mass of the monomers used is set to 100 parts by mass, and mol% refers to values when the total number of moles of the monomers used is set to 100 mol%.​

[0421] [Chemical 49]

[0422]

[0423] [Synthesis Example 1]

[0424] (Synthesis of Polymer (A-1))

[0425] Monomer (M-1), monomer (M-2), monomer (M-5), monomer (M-10) and monomer (M-14) were dissolved in 2-butanone (200 parts by mass) in a molar ratio of 40 / 10 / 20 / 20 / 10 (mol%), and azobisisobutyronitrile (AIBN) as an initiator (5 mol% based on 100 mol% of the total monomers used) was added to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel, and after nitrogen purging for 30 minutes, the inside of the reaction vessel was set to 80 °C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and a 6-hour polymerization reaction was carried out. After the polymerization reaction was completed, the polymerization solution was cooled with water and cooled to 30 °C or lower. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice with methanol and then separated by filtration, and dried at 50 °C for 24 hours to obtain a white powder polymer (A-1) (yield: 85%). The Mw of polymer (A-1) was 7,100, and Mw / Mn was 1.61. In addition, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1), (M-2), (M-5), (M-10) and (M-14) were 40.3 mol%, 9.2 mol%, 20.5 mol%, 19.8 mol% and 10.2 mol%, respectively.

[0426] [Synthesis Examples 2-11]

[0427] (Synthesis of Polymer (A-2) to Polymer (A-11))

[0428] Using the monomers of the types and blending ratios shown in Table 1 below, polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1. The content ratios (mol%) of the respective structural units and physical property values (Mw and Mw / Mn) of the obtained polymers are shown together in Table 1 below. In addition, "-" in Table 1 below indicates that the corresponding monomer was not used (the same applies to the subsequent tables).

[0429] [Table 1]

[0430]

[0431] [Synthesis Example 12]

[0432] (Synthesis of Polymer (A-12))

[0433] The monomers (M-1) and (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) at a molar ratio of 50 / 50 (mol %), and AIBN (5 mol %) as an initiator was added to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the inside of the reaction vessel was set to 80 °C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and a 6-hour polymerization reaction was carried out. After the polymerization reaction was completed, the polymerization solution was cooled with water and cooled to 30 °C or lower. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice with hexane, then separated by filtration, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Subsequently, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a 6-hour hydrolysis reaction was carried out at 70 °C while stirring. After the reaction was completed, the residual solvent was distilled off, the obtained solid was dissolved in acetone (100 parts by mass), and dropped into water (500 parts by mass) to solidify the polymer. The obtained solid was separated by filtration and dried at 50 °C for 13 hours to obtain a white powder polymer (A-12) (yield: 81%). The Mw of polymer (A-12) was 5,500, and Mw / Mn was 1.62. In addition, 13 As a result of 13C-NMR analysis, the content ratios of the respective structural units derived from (M-1) and (M-18) were 50.2 mol % and 49.8 mol %, respectively.

[0434] [Synthesis Examples 13 to 15]

[0435] (Synthesis of Polymers (A-13) to (A-15))

[0436] Using the monomers of the types and blending ratios shown in Table 2 below, polymers (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except for this. In addition, in the monomer providing the structural unit (IV), all the base-dissociable groups were hydrolyzed to phenolic hydroxyl groups. The content ratios (mol %) of the respective structural units and the physical property values (Mw and Mw / Mn) of the obtained polymers are shown together in Table 2 below.

[0437] [Table 2]

[0438]

[0439] [Synthesis Example 16]

[0440] (Synthesis of High-Fluorine-Content Polymer (F-1))

[0441] Monomer (M-1), monomer (M-15), and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 20 / 10 / 70 (mol%). AIBN (4 mol%) as an initiator was added to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel. After purging with nitrogen for 30 minutes, the inside of the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and a 6-hour polymerization reaction was carried out. After the polymerization reaction was completed, the polymerization solution was cooled with water and cooled to 30°C or lower. After replacing the solvent with acetonitrile (400 parts by mass), hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was recovered. The above operation was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine-content polymer (F-1) was obtained (yield: 78%). The Mw of the high-fluorine-content polymer (F-1) was 6,200, and Mw / Mn was 1.77. In addition, 13 As a result of 13C-NMR analysis, the content ratios of the respective structural units derived from (M-1), (M-15), and (M-20) were 20.2 mol%, 9.5 mol%, and 70.3 mol%, respectively.

[0442] [Synthesis Examples 17 to 20]

[0443] (Synthesis of High-Fluorine-Content Polymer (F-2) to High-Fluorine-Content Polymer (F-5))

[0444] Using the monomers of the types and blending ratios shown in Table 3 below, high-fluorine-content polymers (F-2) to high-fluorine-content polymers (F-5) were synthesized in the same manner as in Synthesis Example 16. The content ratios (mol%) of the respective structural units and the physical property values (Mw and Mw / Mn) of the obtained high-fluorine-content polymers are shown together in Table 3 below.

[0445]

[0446] <Synthesis of Onium Salt Compound (1)>

[0447] [Example B1]

[0448] (Synthesis of Compound (B-1))

[0449] Compound (B-1) was synthesized according to the following synthesis process.

[0450] [Chemical Formula 50]

[0451]

[0452] In a reaction vessel, 20.0 mmol of cyclopentadiene and 50 g of chloromethane were added to 20.0 mmol of 4-bromo-3,3,4,4-tetrafluoro-1-butene, and the mixture was stirred at room temperature for 3 hours. Thereafter, after adding water for dilution, chloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was successively washed with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby an olefin compound was obtained in good yield.

[0453] 40.0 mmol of potassium permanganate and 50 g of acetonitrile were added to the olefin compound, and the mixture was stirred at 50 °C for 10 hours. Thereafter, after adding a saturated aqueous sodium thiosulfate solution to stop the reaction, ethyl acetate was added for extraction, and the organic layer was separated. The obtained organic layer was successively washed with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby a diol compound was obtained in good yield.

[0454] 20.0 mmol of 5-acetylsalicylic acid, 2.00 mmol of sulfuric acid and 50 g of dichloromethane were added to the diol compound, and the mixture was stirred at room temperature for 24 hours. Thereafter, after adding water for dilution, ethyl acetate was added for extraction, and the organic layer was separated. The obtained organic layer was successively washed with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby an acetal compound was obtained in good yield.

[0455] After adding a mixed solution of acetonitrile:water (1:1 (mass ratio)) to the acetal compound to prepare a 1 M solution, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium hydrogen carbonate were added, and the reaction was carried out at 70 °C for 4 hours. After extraction with acetonitrile and distilling off the solvent, a mixed solution of acetonitrile:water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 60.0 mmol of hydrogen peroxide solution and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50 °C for 12 hours. After extraction with acetonitrile and distilling off the solvent, a sodium sulfonate compound was obtained. 20.0 mmol of triphenylsulfonium bromide was added to the sodium sulfonate compound, and a mixed solution of water:dichloromethane (1:3 (mass ratio)) was added thereto to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby the compound (B-1) represented by the formula (B-1) was obtained in good yield.

[0456] [Examples B2 - B9]

[0457] (Synthesis of Compounds (B - 2) - (B - 9))

[0458] Appropriately change the raw materials and precursors. Except for this, synthesize the onium salt compounds (1) represented by the following formulas (B - 2) - (B - 9) in the same manner as in Example B1.

[0459] [Chemical Formula 51]

[0460]

[0461] [Example B10]

[0462] (Synthesis of Compound (B - 10))

[0463] Synthesize Compound (B - 10) according to the following synthesis process.

[0464] [Chemical Formula 52]

[0465]

[0466] Add 20.0 mmol of 4 - bromo - 3,3,4,4 - tetrafluoro - 1 - butene, 40.0 mmol of potassium permanganate, and 50 g of acetonitrile to a reaction vessel, and stir at 50 °C for 10 hours. After that, add a saturated aqueous solution of sodium thiosulfate to stop the reaction, then add ethyl acetate for extraction, and separate the organic layer. Wash the obtained organic layer successively with a saturated aqueous solution of sodium chloride and water. After drying with sodium sulfate, distill off the solvent, and purify by column chromatography to obtain the diol in good yield.

[0467] Add 20.0 mmol of 5 - formylsalicylic acid, 2.00 mmol of sulfuric acid, and 50 g of dichloromethane to the diol, and stir at room temperature for 24 hours. After that, add water for dilution, then add ethyl acetate for extraction, and separate the organic layer. Wash the obtained organic layer successively with a saturated aqueous solution of sodium chloride and water. After drying with sodium sulfate, distill off the solvent, and purify by column chromatography to obtain the acetal in good yield.

[0468] After adding a mixed solution of acetonitrile: water (1:1 (mass ratio)) to the acetal to prepare a 1 M solution, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the reaction was carried out at 70 °C for 4 hours. After extraction with acetonitrile and removal of the solvent by distillation, a mixed solution of acetonitrile: water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 60.0 mmol of hydrogen peroxide solution and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50 °C for 12 hours. After extraction with acetonitrile and removal of the solvent by distillation, the sodium sulfonate compound was obtained. 20.0 mmol of triphenylsulfonium bromide was added to the sodium sulfonate compound, and a mixed solution of water: dichloromethane (1:3 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and purification was carried out by column chromatography to obtain the compound (B-10) represented by the formula (B-10) in good yield.

[0469] [Example B11]

[0470] (Synthesis of compound (B-11))

[0471] Compound (B-11) was synthesized according to the following synthetic procedure.

[0472] [Chemical formula 53]

[0473]

[0474] After adding a mixed solution of acetonitrile: water (1:1 (mass ratio)) to 20.0 mmol of ethyl bromodifluoroacetate to prepare a 1 M solution, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the reaction was carried out at 70 °C for 4 hours. After extraction with acetonitrile and removal of the solvent by distillation, a mixed solution of acetonitrile: water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 60.0 mmol of hydrogen peroxide solution and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50 °C for 12 hours. After extraction with acetonitrile and removal of the solvent by distillation, the sodium sulfonate compound was obtained. 20.0 mmol of triphenylsulfonium bromide was added to the sodium sulfonate compound, and a mixed solution of water: dichloromethane (1:3 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and purification was carried out by column chromatography to obtain the sulfonium salt.

[0475] After adding a mixed solution of methanol:water (1:1 (mass ratio)) to the onium salt to prepare a 1 M solution, 20.0 mmol of lithium hydroxide was added, and the reaction was carried out at room temperature for 2 hours. After that, 2 M hydrochloric acid was added to stop the reaction, and then methyl chloride was added for extraction, and the organic layer was separated. For the obtained organic layer, after drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby the compound (B-11-1) represented by the formula (B-11-1) was obtained in good yield.

[0476] To the compound (B-11-1), 20.0 mmol of 4-(2-hydroxyethoxy)salicylic acid, 20.0 mmol of dicyclohexylcarbodiimide, 2.0 mmol of 4-dimethylaminopyridine and 50 g of methyl chloride were added, and the mixture was stirred at room temperature for 3 hours. After that, it was diluted with 1 M hydrochloric acid, and then methyl chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed successively with saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby the compound (B-11) represented by the formula (B-11) was obtained in moderate yield.

[0477] [Examples B12 - B13]

[0478] (Synthesis of Compounds (B-12) - (B-13))

[0479] The starting materials and precursors were appropriately changed, and except for this, the onium salt compounds (1) represented by the following formula (B-12) - formula (B-13) were synthesized in the same manner as in Example B11.

[0480] [Chemical Formula 54]

[0481]

[0482] [Example B14]

[0483] (Synthesis of Compound (B-14))

[0484] Compound (B-14) was synthesized according to the following synthetic route.

[0485] [Chemical Formula 55]

[0486]

[0487] Add 20.0 mmol of the compound (B-11-1), 20.0 mmol of 1,2-isopropylidene glycerol, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methyl chloride to a reaction vessel, and stir at room temperature for 10 hours. Then, after adding water for dilution, add ethyl acetate for extraction, and separate the organic layer. For the obtained organic layer, wash successively with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, distill off the solvent, and purify by column chromatography to obtain the ester compound in good yield.

[0488] Add 20.0 mmol of 5-acetylsalicylic acid, 2.00 mmol of sulfuric acid, and 50 g of dichloroethane to the ester compound, and stir at 70 °C for 24 hours. Then, after adding water for dilution, add dichloromethane for extraction, and separate the organic layer. For the obtained organic layer, wash successively with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, distill off the solvent, and purify by column chromatography to obtain the compound (B-14) represented by the formula (B-14) in good yield.

[0489] [Example B15]

[0490] (Synthesis of compound (B-15))

[0491] Synthesize the compound (B-15) according to the following synthetic process.

[0492] [Chemical formula 56]

[0493]

[0494] Add 20.0 mmol of the compound (B-11-1), 20.0 mmol of the compound (B-15-1), 3.0 mmol of p-toluenesulfonic acid monohydrate, and 50 g of toluene to a reaction vessel, and stir at 100 °C for 10 hours. Then, after adding a saturated aqueous sodium bicarbonate solution to stop the reaction, add dichloromethane for extraction, and separate the organic layer. For the obtained organic layer, wash successively with a saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, distill off the solvent, and purify by column chromatography to obtain the ester compound in good yield.

[0495] After adding a mixed solution of acetonitrile: water (1:1 (mass ratio)) to the ester body to prepare a 1 M solution, 20.0 mmol of lithium hydroxide was added, and the reaction was carried out at room temperature for 2 hours. After that, 2 M hydrochloric acid was added to stop the reaction, and then chloromethane was added for extraction, and the organic layer was separated. For the obtained organic layer, after drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby the compound (B-15) represented by the formula (B-15) was obtained in a moderate yield.

[0496] [Example B16]

[0497] (Synthesis of compound (B-16))

[0498] Compound (B-16) was synthesized according to the following synthetic process.

[0499] [Chemical Formula 57]

[0500]

[0501] 20.0 mmol of 4-bromo-3,3,4,4-tetrafluorobutan-1-ol, 20.0 mmol of the compound (B-16-1), 20.0 mmol of dicyclohexylcarbodiimide and 50 g of acetonitrile were added to a reaction vessel, and the mixture was stirred at room temperature for 10 hours. After that, water was added for dilution, and then ethyl acetate was added for extraction, and the organic layer was separated. The obtained organic layer was washed successively with saturated aqueous sodium chloride solution and water. After drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby an ester body was obtained in a good yield.

[0502] After adding a mixed solution of acetonitrile: water (1:1 (mass ratio)) to the ester body to prepare a 1 M solution, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the reaction was carried out at 70 °C for 4 hours. After extraction with acetonitrile and distilling off the solvent, a mixed solution of acetonitrile: water (3:1 (mass ratio)) was added to prepare a 0.5 M solution. 60.0 mmol of hydrogen peroxide solution and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50 °C for 12 hours. After extraction with acetonitrile and distilling off the solvent, a sodium sulfonate compound was obtained. 20.0 mmol of triphenylsulfonium bromide was added to the sodium sulfonate compound, and a mixed solution of water: dichloromethane (1:3 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. For the obtained organic layer, after drying with sodium sulfate, the solvent was distilled off, and purification was carried out by column chromatography, whereby the compound (B-16) represented by the formula (B-16) was obtained in a good yield.

[0503] [Examples B17 - B20]

[0504] (Synthesis of Compounds (B - 17) - (B - 20))

[0505] Appropriately change the raw materials and precursors. Except for this, synthesize the onium salt compounds (1) represented by the following formulas (B - 17) - (B - 20) in the same manner as in Example B16.

[0506] [Chemical Formula 58]

[0507]

[0508] <Synthesis of Onium Salt Compounds (Radiation - Sensitive Acid Generators) Other than the Above>

[0509] As components other than the components of the above synthesis, use the following compounds.

[0510] [Onium Salt Compounds (Radiation - Sensitive Acid Generators) Other than (B - 1) - (B - 20)]

[0511] b - 1 to b - 8: Compounds represented by the following formulas (b - 1) - (b - 8) (hereinafter, the compounds represented by formulas (b - 1) - (b - 8) may be respectively referred to as "Compound (b - 1)" - "Compound (b - 8)")

[0512] [Chemical Formula 59]

[0513]

[0514] <Synthesis of Acid Diffusion Controller D>

[0515] [Example D1]

[0516] (Synthesis of Compound (D - 1))

[0517] Synthesize Compound (D - 1) according to the following synthesis process.

[0518] [Chemical Formula 60]

[0519]

[0520] 20.0 mmol of sodium 2-hydroxyethanesulfonate, 20.0 mmol of the compound (B-16-1), 20.0 mmol of dicyclohexylcarbodiimide and 50 g of dichloromethane were added to a reaction vessel, and the mixture was stirred at room temperature for 10 hours. Then, 50 g of water was added for dilution, and 20.0 mmol of 4-methylphenyldiphenylsulfonium bromide was added, and the mixture was vigorously stirred at room temperature for 3 hours. Then, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain the compound (D-1) represented by the formula (D-1) in good yield.

[0521] [Example D2]

[0522] (Synthesis of compound (D-2))

[0523] The raw materials and precursors were appropriately changed, and otherwise, the acid diffusion control agent represented by the following formula (D-2) was synthesized in the same manner as in Example D1.

[0524] [Chemical formula 61]

[0525]

[0526] [Example D3]

[0527] (Synthesis of compound (D-3))

[0528] Compound (D-3) was synthesized according to the following synthetic route.

[0529] [Chemical formula 62]

[0530]

[0531] 20.0 mmol of bromoacetyl bromide, 20.0 mmol of 4-(2-hydroxyethoxy)salicylic acid, 20.0 mmol of triethylamine and 50 g of acetonitrile were added to a reaction vessel, and the mixture was stirred at room temperature for 10 hours. Then, water was added for dilution, ethyl acetate was added for extraction, and the organic layer was separated. The obtained organic layer was washed successively with saturated aqueous sodium chloride solution and water. After drying over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain the ester in moderate yield.

[0532] After adding a mixed solution of acetonitrile: water (1:1 (mass ratio)) to the ester body to make a 1 M solution, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the reaction was carried out at 70 °C for 4 hours. After extraction with acetonitrile and removal of the solvent by distillation, a mixed solution of acetonitrile: water (3:1 (mass ratio)) was added to make a 0.5 M solution. 60.0 mmol of hydrogen peroxide solution and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50 °C for 12 hours. After extraction with acetonitrile and removal of the solvent by distillation, the sodium sulfonate compound was obtained. 20.0 mmol of 4-methylphenyldiphenylsulfonium bromide was added to the sodium sulfonate compound, and a mixed solution of water: dichloromethane (1:3 (mass ratio)) was added to make 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 with sodium sulfate, the solvent was removed by distillation, and purification was carried out by column chromatography, whereby the compound (D-3) represented by the formula (D-3) was obtained in good yield.

[0533] [Example D4]

[0534] (Synthesis of compound (D-4))

[0535] Appropriately changing the raw materials and precursors, and otherwise, the acid diffusion control agent represented by the following formula (D-4) was synthesized in the same manner as in Example D3.

[0536] [Chemical formula 63]

[0537]

[0538] [Acid diffusion control agents other than acid diffusion control agent (D-1) to acid diffusion control agent (D-4)]

[0539] d-1 to d-8: Compounds represented by the following formulas (d-1) to (d-8) (hereinafter, the compounds represented by the formulas (d-1) to (d-8) may be sometimes referred to as "compound (d-1)" to "compound (d-8)")

[0540] [Chemical formula 64]

[0541]

[0542] [[E] Solvent]

[0543] E-1: Propylene glycol monomethyl ether acetate

[0544] E-2: Propylene glycol monomethyl ether

[0545] E-3: γ-Butyrolactone

[0546] [Preparation of Positive-Type Radiation-Sensitive Composition for ArF Immersion Lithography]

[0547] [Example 1]

[0548] 100 parts by mass of (A-1) as the [A] polymer, 10.0 parts by mass of (B-1) as the [B] onium salt compound (1) (radiation-sensitive acid generator), 6.0 parts by mass of (d-1) as the [D] acid diffusion control agent, 5.0 parts by mass (solid content) of (F-1) as the [F] high-fluorine content polymer, and 3,400 parts by mass of the mixed solvent (E-1) / (E-2) / (E-3) as the [E] solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare the radiation-sensitive composition (J-1).

[0549] [Examples 2 to 49 and Comparative Examples 1 to 6]

[0550] Using the components of the types and contents shown in Table 4 below, the radiation-sensitive compositions (J-2) to (J-49) and the radiation-sensitive compositions (CJ-1) to (CJ-6) were prepared in the same manner as in Example 1, except for this.

[0551] [Table 4]

[0552]

[0553]

[0554] <Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Composition for ArF Immersion Lithography>

[0555] Using a spin coater (“CLEAN TRACK ACT12” by Tokyo Electron Limited), a composition for forming a lower antireflection film (“ARC66” by Brewer Science, Inc.) was coated on a 12-inch silicon wafer and then heated at 205°C for 60 seconds to form a lower antireflection film with an average thickness of 100 nm. Using the spin coater, the prepared positive-type radiation-sensitive composition for ArF exposure was coated on the lower antireflection film and prebaked (PB) at 100°C for 60 seconds. Then, it was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 110 nm. Next, for the resist film, using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” by ASML), exposure was performed with an optical condition of NA = 1.35 and dipole (σ = 0.9 / 0.7) through a mask pattern of 60 nm line and space. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Then, using a 2.38 mass% aqueous TMAH solution as an alkaline developer, the resist film was alkali-developed, washed with water after development, and further dried to form a positive-type resist pattern (60 nm line and space pattern).

[0556] <Evaluation>

[0557] For the resist pattern formed using the positive-type radiation-sensitive composition for ArF immersion exposure, sensitivity, LWR, pattern rectangularity, EL, and the number of development defects were evaluated according to the following method. The results are shown in Table 5 below. In addition, for the length measurement of the resist pattern, a scanning electron microscope (“CG-5000” by Hitachi High-Technologies Corporation) was used. The results are shown in Table 5 below.

[0558] [Sensitivity]

[0559] In the formation of the resist pattern using the positive-type radiation-sensitive composition for ArF immersion exposure, the exposure amount for forming a 60 nm line and space pattern was set as the most preferred exposure amount, and the most preferred exposure amount was defined as the sensitivity (mJ / cm 2 ). Regarding sensitivity, a case of 30 mJ / cm 2 or less was evaluated as “good”, and a case exceeding 30 mJ / cm 2 was evaluated as “bad”.

[0560] [LWR]

[0561] Irradiate the most preferred exposure dose obtained in the evaluation of the sensitivity to form a resist pattern of 60 nm lines and spaces. Using the scanning electron microscope, observe the formed resist pattern from above the pattern. Measure the deviation of the line widths at a total of 500 locations, and obtain the 3-sigma value based on the distribution of the measured values. Set the 3-sigma value as LWR (nm). The smaller the value of LWR, the smaller the line roughness and the better. Regarding LWR, a case of 2.5 nm or less is evaluated as "good", and a case exceeding 2.5 nm is evaluated as "bad".

[0562] [Pattern Rectangularity]

[0563] For the 60 nm line and space resist pattern formed with the most preferred exposure dose obtained in the evaluation of the irradiation sensitivity, observe it using the scanning electron microscope and evaluate the cross-sectional shape of the line and space pattern. Regarding the rectangularity of the resist pattern, if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape is 1 or more and 1.05 or less, it is evaluated as "A" (extremely good); if it exceeds 1.05 and is 1.10 or less, it is evaluated as "B" (good); if it exceeds 1.10, it is evaluated as "C" (bad).

[0564] [Number of Development Defects]

[0565] Expose the resist film with the most preferred exposure dose to form a line and space pattern with a line width of 60 nm, and use it as a wafer for defect inspection. Use a defect inspection device ("KLA2810" from KLA-Tencor Corporation) to measure the number of defects on the wafer for defect inspection. Determine the defects with a diameter of 50 μm or less as defects originating from the resist film and calculate their number. Regarding the number of defects after development, a case where the number of defects determined to originate from the resist film is 30 or less is evaluated as "good", and a case exceeding 30 is evaluated as "bad".

[0566] [EL (Exposure Latitude)]

[0567] Within the range of exposure doses including the optimal exposure dose, at 1 mJ / cm 2The exposure amount is changed in units to form resist patterns respectively, and the line width of each is measured using the scanning electron microscope. Based on the relationship between the obtained line width and the exposure amount, the exposure amount E(66) for a line width of 66 nm and the exposure amount E(54) for a line width of 54 nm are obtained, and the exposure latitude (%) is calculated according to the formula of exposure latitude (EL) = (E(54) - E(66)) × 100 / (optimal exposure amount). The larger the value of the exposure latitude, the smaller the change in the size of the pattern obtained when the exposure amount varies, and the yield in device fabrication can be improved. Regarding EL, a case of 10% or more is evaluated as "good", and a case of less than 10% is evaluated as "bad".

[0568] [Table 5]

[0569]

[0570]

[0571] As is clear from the results in Table 5, when the radiation-sensitive composition of the example is used for ArF immersion exposure, the sensitivity, LWR, pattern rectangularity, EL, and development defect performance are good. In contrast, in the comparative examples, each characteristic is inferior compared to the example. Therefore, when the radiation-sensitive composition of the example is used for ArF immersion exposure, a resist pattern with good LWR, EL, and pattern rectangularity and few development defects can be formed with high sensitivity.

[0572] [Preparation of Positive-Type Radiation-Sensitive Composition for Extreme Ultraviolet (EUV) Exposure]

[0573] [Example 50]

[0574] 100 parts by mass of (A-12) as the [A] polymer, 30.0 parts by mass of (B-1) as the [B] onium salt compound (1) (radiation-sensitive acid generator), 20.0 parts by mass of (d-1) as the [D] acid diffusion control agent, 5.0 parts by mass (solid content) of (F-5) as the [F] high-fluorine content polymer, and 6,000 parts by mass of the mixed solvent of (E-1) / (E-2) / (E-3) as the [E] solvent are mixed and filtered using a membrane filter with a pore size of 0.2 μm to prepare the radiation-sensitive composition (J-50).

[0575] [Examples 51 to 65 and Comparative Examples 7 to 9]

[0576] Using the components of the types and contents shown in Table 6 below, except for this, the radiation-sensitive compositions (J-51) to (J-65) and the radiation-sensitive compositions (CJ-7) to (CJ-9) are prepared in the same manner as in Example 50.

[0577] [Table 6]

[0578]

[0579] <Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Composition for EUV Exposure>

[0580] Using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), a composition for forming an underlayer antireflection film ("ARC66" manufactured by Brewer Science, Inc.) was coated on a 12-inch silicon wafer and then heated at 205°C for 60 seconds to form an underlayer antireflection film with an average thickness of 105 nm. The prepared positive-type radiation-sensitive composition for EUV exposure was coated on the underlayer antireflection film using the spin coater, and PB was performed at 130°C for 60 seconds. Thereafter, it was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. Next, for the resist film, using an EUV exposure apparatus ("NXE3300" manufactured by ASML), exposure was performed with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Thereafter, using a 2.38 mass% aqueous TMAH solution as an alkaline developer, the resist film was alkali-developed, washed with water after development, and then dried to form a positive-type resist pattern (25 nm line and space pattern).

[0581] <Evaluation>

[0582] For the resist pattern formed using the positive-type radiation-sensitive composition for EUV exposure, sensitivity, LWR, EL, and the number of development defects were evaluated according to the following method. The results are shown in Table 7 below. In addition, in the measurement of the length of the resist pattern, a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation) was used.

[0583] [Sensitivity]

[0584] In the formation of the resist pattern using the positive-type radiation-sensitive composition for EUV exposure, the exposure amount for forming a 25 nm line and space pattern was set as the most preferred exposure amount, and the most preferred exposure amount was defined as the sensitivity (mJ / cm 2 ). Regarding the sensitivity, a case where it is 40 mJ / cm 2 or less was evaluated as "good", and a case where it exceeds 40 mJ / cm 2 was evaluated as "bad".

[0585] [LWR]

[0586] Adjust the mask size to form a resist pattern by using the most preferred exposure dose obtained in the evaluation of the sensitivity, so as to form a 25 nm line and space pattern. Observe the formed resist pattern from above the pattern by using the scanning electron microscope. Measure the deviation of the line widths at a total of 500 locations, and obtain the 3-sigma value based on the distribution of the measured values. Set the 3-sigma value as LWR (nm). The smaller the value of LWR, the smaller the line wobbling and the better. Regarding LWR, a case where it is 3.0 nm or less is evaluated as "good", and a case where it exceeds 3.0 nm is evaluated as "bad".

[0587] [Number of development defects]

[0588] Expose the resist film with the most preferred exposure dose to form a line and space pattern with a line width of 25 nm, and use it as a wafer for defect inspection. Measure the number of defects on the wafer for defect inspection by using a defect inspection device ("KLA2810" of KLA-Tencor Corporation). Judge the defects with a diameter of 50 μm or less as defects originating from the resist film, and calculate the number thereof. Regarding the number of defects after development, a case where the number of defects judged to be from the resist film is 50 or less is evaluated as "good", and a case where it exceeds 50 is evaluated as "bad".

[0589] [EL (Exposure Latitude)]

[0590] Within the range of exposure doses including the optimal exposure dose, change the exposure dose in units of 1 mJ / cm 2 to form resist patterns respectively, and measure the line widths of each by using the scanning electron microscope. According to the relationship between the obtained line width and the exposure dose, obtain the exposure dose E(28) with a line width of 28 nm and the exposure dose E(22) with a line width of 22 nm, and calculate the exposure latitude (%) according to the formula of exposure latitude (EL) = (E(22) - E(28)) × 100 / (optimal exposure dose). The larger the value of the exposure latitude, the smaller the change in the size of the pattern obtained when the exposure dose changes, and the yield during device fabrication can be improved. Regarding EL, a case where it is 7% or more is evaluated as "good", and a case where it is less than 7% is evaluated as "bad".

[0591] [Table 7]

[0592]

[0593] As is clear from the results in Table 7, when the radiation-sensitive composition of the example is used for EUV exposure, the sensitivity, LWR, EL, and development defect performance are good. In contrast, in the comparative example, each characteristic is poor compared with the example.

[0594] [Preparation of Negative-Type Radiation-Sensitive Composition for ArF Exposure, Formation and Evaluation of Resist Pattern Using the Composition]

[0595] [Example 66]

[0596] 100 parts by mass of (A-8) as [A] polymer, 8.0 parts by mass of (B-1) as [B] onium salt compound (1) (radiation-sensitive acid generator), 7.0 parts by mass of (d-2) as [D] acid diffusion control agent, 2.0 parts by mass of (F-4) as [F] high-fluorine-content polymer (solid content), and 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio 2,240 / 960 / 30) as [E] solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-66).

[0597] Using a spin coater (“CLEAN TRACK ACT12” of Tokyo Electron Co., Ltd.), a composition for forming an underlayer antireflection film (“ARC66” of Brewer Science, Inc.) was coated on a 12-inch silicon wafer and then heated at 205 °C for 60 seconds to form an underlayer antireflection film with an average thickness of 100 nm. The prepared negative-type radiation-sensitive composition for ArF exposure (J-66) was coated on the underlayer antireflection film using the spin coater and prebaked (PB) at 100 °C for 60 seconds. Then, it was cooled at 23 °C for 30 seconds to form a resist film with an average thickness of 90 nm. Next, for the resist film, using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” of ASML), exposure was performed with an optical condition of NA = 1.35, Annular (σ = 0.8 / 0.6), through a mask pattern with 50-nm holes and 100-nm pitch. After exposure, post-exposure baking (PEB) was performed at 100 °C for 60 seconds. Then, using n-butyl acetate as an organic solvent developer, the resist film was developed with an organic solvent and dried to form a negative-type resist pattern (contact hole pattern with 50-nm holes and 100-nm pitch).

[0598] For the resist pattern using the negative-type radiation-sensitive composition for ArF exposure, the sensitivity was evaluated in the same manner as for the resist pattern using the positive-type radiation-sensitive composition for ArF exposure. In addition, CDU and pattern circularity were evaluated according to the following methods.

[0599] [CDU]

[0600] The most preferred exposure dose obtained in the evaluation of the irradiation sensitivity is used to form contact holes with a 50 nm hole and a 100 nm pitch. Using the scanning electron microscope, the formed resist pattern is observed from above the pattern. The deviation of a total of 500 contact holes is measured, and the 3-sigma value is obtained based on the distribution of the measured values. The 3-sigma value is set as CDU (nm). The smaller the value of CDU, the smaller the roughness of the holes and the better. Regarding CDU, a case where it is less than 3.5 nm is evaluated as "good", and a case where it is 3.5 nm or more is evaluated as "bad".

[0601] [Pattern circularity]

[0602] For the contact holes with a 50 nm hole and a 100 nm pitch formed with the most preferred exposure dose obtained in the evaluation of the irradiation sensitivity, the formed resist pattern is observed from above using the scanning electron microscope, and the longitudinal dimension and the transverse dimension are measured respectively. If the ratio of the longitudinal dimension / the transverse dimension is 0.95 or more and less than 1.05, it is evaluated as "A" (extremely good). If it is 0.90 or more and less than 0.95, or 1.05 or more and less than 1.10, it is evaluated as "B" (good). If it is less than 0.90 or 1.10 or more, it is evaluated as "C" (bad).

[0603] As a result, even when the radiation-sensitive composition of Example 66 is used to form a negative resist pattern by ArF exposure, the sensitivity, CDU, and pattern circularity are good.

[0604] [Preparation of a negative radiation-sensitive composition for EUV exposure, formation and evaluation of a resist pattern using the composition]

[0605] [Example 67]

[0606] 100 parts by mass of (A-13) as the [A] polymer, 30.0 parts by mass of (B-5) as the [B] onium salt compound (1) (radiation-sensitive acid generator), 15.0 parts by mass of (d-4) as the [D] acid diffusion control agent, 2.0 parts by mass (solid content) of (F-5) as the [F] high-fluorine content polymer, and 6,000 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio 1,000 / 4,900 / 100) as the [E] solvent are mixed and filtered using a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-67).

[0607] Using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), a composition for forming an underlayer antireflection film (“ARC66” manufactured by Brewer Science, Inc.) was coated on a 12-inch silicon wafer and then heated at 205° C. for 60 seconds to form an underlayer antireflection film with an average thickness of 105 nm. Using the spin coater, the prepared negative-type radiation-sensitive composition for EUV exposure (J-67) was coated on the underlayer antireflection film, and PB was performed at 130° C. for 60 seconds. Thereafter, it was cooled at 23° C. for 30 seconds to form a resist film with an average thickness of 55 nm. Next, for the resist film, using an EUV exposure apparatus (“NXE3300” manufactured by ASML), exposure was performed with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR15. After the exposure, PEB was performed at 120° C. for 60 seconds. Thereafter, using n-butyl acetate as an organic solvent developer, the resist film was developed with an organic solvent and dried to form a negative-type resist pattern (a contact hole pattern with 20-nm holes and 40-nm pitch).

[0608] Regarding the resist pattern using the negative-type radiation-sensitive composition for EUV exposure, evaluation was performed in the same manner as the evaluation of the resist pattern using the negative-type radiation-sensitive composition for ArF exposure. As a result, even when a negative-type resist pattern was formed by EUV exposure, the radiation-sensitive composition of Example 67 exhibited good sensitivity, CDU, and pattern circularity.

[0609] Industrial Applicability

[0610] According to the radiation-sensitive composition and the resist pattern forming method described above, a resist pattern having good sensitivity to exposure light and excellent LWR, pattern rectangularity, development defect performance, EL, CDU, and pattern circularity can be formed. Therefore, these can be preferably used in processing processes of semiconductor devices and the like that are expected to be further miniaturized in the future.

Claims

1. A radiation-sensitive composition containing: an onium salt compound represented by the following formula (1), a polymer containing a structural unit having an acid-dissociable group, and a solvent. [Chemical formula 1] (In formula (1), W is an organic group having at least one ring structure and having 3 to 40 carbon atoms. L is an (r + 1)-valent linking group, and r is an integer of 1 to 3. Regarding p and q, when r is 1, both p and q are integers of 1 to 3, and when r is 2 to 3, a plurality of p's and q's are integers of 0 to 3, respectively. Among them, When r is from 2 to 3, at least one of the plurality of p is 1 or more, and at least one of the plurality of q is 1 or more. M + is a monovalent onium cation.).

2. The radiosensitive composition according to claim 1, wherein, The partial structure "-W(OH) p (COOH) q " in the formula (1) includes one or more groups selected from the group consisting of the groups represented by the following formula (W-1) to formula (W-5). [Chemical formula 2] (In the formula, s is an integer from 0 to 2, t is an integer from 1 to 3. l, m, and n are each independently an integer from 1 to 6. X is a hydrogen atom, an organic group having 1 to 12 carbon atoms, a cyano group, a hydroxyl group, or a halogen atom. b is an integer from 1 to 10. When b is 2 or more, the plurality of Xs may be the same or different. R 1 , R 2 are each the same as or different from each other and are a single bond or a divalent organic group.).

3. The radiation-sensitive composition according to claim 1, wherein, A partial structure in the formula (1) "-W(OH) p (COOH) q " contains one or more groups selected from the group consisting of the groups represented by the following formulas (W-6) to (W-9), and contains one or more groups selected from the group consisting of groups represented by the following formulas (W-10) to (W-13). [Chemical formula 3] (In the formula, s is an integer from 0 to 2, t is an integer from 1 to 3. l, m, and n are each independently an integer from 1 to 6. X is a hydrogen atom, an organic group having 1 to 12 carbon atoms, a cyano group, a hydroxyl group, or a halogen atom. b is an integer from 1 to 10. When b is 2 or more, the plurality of Xs may be the same or different. R 1 , R 2 are each the same as or different from each other and are a single bond or a divalent organic group.).

4. The radio-sensitive composition according to claim 1, wherein, The L has one or more bonding groups selected from the group consisting of an ether bond, an amide bond, an ester bond, and an acetal bond.

5. The radiosensitive composition according to claim 4, wherein, The L is at least one structure selected from the structures represented by the following formulas (L-1) to (L-5). [Chemical formula 4] (In formula (L-1), R 11 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. R 12 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to S of SO3 - in the formula (1).) [Chemical formula 5] (In formula (L-2), R 13 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. R 14 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to the S of SO3 - in the formula (1).) [Chemical formula 6] (In formula (L-3), R 21 , R 22 are the same as or different from each other and are a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms, and a is an integer of 1 to 3. * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to the S of SO3 - in the formula (1).) [Chemical formula 7] (In formula (L-4), Y 11 and Y 12 are each independently an oxygen atom or a sulfur atom. R 41 is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent organic group represented by -X 1 -Y-X 2 (wherein X 1 is a single bond or a divalent hydrocarbon group having 1 to 11 carbon atoms, Y is -O-, -CO-, -COO-, -OCO-, -OCOO-, -NHCO- or -CONH-, and X 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms).). R 42 is a single bond, or a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R 43 is a single bond or a divalent organic group. Q forms a monocyclic or condensed-ring cyclic (thio)acetal structure together with Y 11 , Y 12 and the carbon atom to which these are bonded. * is a bonding bond bonded to W in the formula (1), and ** is a bonding bond bonded to the S of SO3 - in the formula (1).) [Chemical formula 8] (In formula (L-5), Y 11 , Y 12 , R 42 , R 43 , Q have the same meanings as in the formula (L-4). R 44 is a single bond or a divalent organic group. * is a bonding bond that bonds with W in the formula (1), and ** is a bonding bond that bonds with S of SO3 - in the formula (1).).

6. The radiosensitive composition according to claim 1, wherein, The L contains a ring structure, and the ring structure of the L forms a spiro ring structure with the ring structure possessed by W.

7. The radio-sensitive composition according to claim 1, wherein, The carboxyl group and the hydroxyl group bonded to W in the formula (1) are directly bonded to the same or different ring structures, respectively.

8. The radio-sensitive composition according to claim 1, wherein, The structural unit having an acid-dissociable group is represented by the following formula (2). [Chemical formula 9] (In formula (2), R 51 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 52 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. R 53 and R 54 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 R 53 and R 54 are bonded to each other and together with the carbon atoms to which they are bonded form a divalent alicyclic group having 3 to 20 carbon atoms. L 81 is a single bond or a divalent organic group.).

9. A pattern forming method, comprising: a step of directly or indirectly coating the radiation-sensitive composition according to any one of claims 1 to 8 on a substrate to form a resist film; a step of exposing the resist film; and a step of developing the exposed resist film.

10. The pattern forming method according to claim 9, wherein, In the developing step, the exposed resist film is developed with an alkaline developer.

11. The pattern forming method according to claim 9, wherein, The exposure is performed by ArF excimer laser or extreme ultraviolet ray.

12. A radiation-sensitive acid generator represented by the following formula (1). [Chemical formula 10] (In formula (1), W is an organic group having at least one ring structure and having 3 to 40 carbon atoms. L is an (r + 1)-valent linking group, and r is an integer of 1 to 3. Regarding p and q, when r is 1, both p and q are integers of 1 to 3, and when r is 2 to 3, a plurality of p's and q's are integers of 0 to 3 respectively. Among them, When r is from 2 to 3, at least one of the plurality of p is 1 or more, and at least one of the plurality of q is 1 or more. M + is a monovalent onium cation.).

13. The radiation-sensitive acid generator according to claim 12, wherein, The partial structure "-W(OH) p (COOH) q " in the formula (1) includes one or more groups selected from the group consisting of the groups represented by the following formula (W-1) to formula (W-5). [Chemical formula 11] (In the formula, s is an integer from 0 to 2, t is an integer from 1 to 3. l, m, and n are each independently an integer from 1 to 6. X is a hydrogen atom, an organic group having 1 to 12 carbon atoms, a cyano group, a hydroxyl group, or a halogen atom. b is an integer from 1 to 10. When b is 2 or more, the plurality of Xs may be the same or different. R 1 , R 2 are the same as or different from each other and are a single bond or a divalent organic group.).

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