Onium salt compounds

Abstract

The present invention provides a radiation-sensitive resin composition, etc., capable of forming a resist film that exhibits sufficient levels of sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity, even when forming a high aspect ratio resist pattern. [Solution] A radiation-sensitive resin composition comprising a first onium salt compound represented by the following formula (1), a second onium salt compound represented by a specific formula, a resin containing structural units having acid-dissociable groups, and a solvent. TIFF2026065129000049.tif61169

Description

[Technical Field]

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

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

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

[0004] As efforts to further advance the technology progress, attempts are also being made to improve the sensitivity and resolution of photoacid generators, which are the main components of resist compositions. For example, an acid generator capable of imparting a strong acid by substituting the proximal carbon of the sulfonic acid group with fluorine is being investigated (see Patent No. 5703702). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5703702 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Further applications may involve forming high-aspect-ratio resist patterns with line widths and hole diameters of 100 nm or less and resist film thicknesses of 100 nm to 200 nm or more. When forming such high-aspect-ratio patterns, the resist performance is required to be equivalent to or better than conventional resists in terms of sensitivity, critical dimension uniformity (CDU) performance (an indicator of the uniformity of line width and hole diameter), pattern circularity (indicating the roundness of the hole shape), LWR (Line Width Roughness) performance (indicating the variation in the line width of the resist pattern), and pattern rectangularity (indicating the rectangularity of the cross-sectional shape of the resist pattern).

[0007] The present invention aims to provide a radiation-sensitive resin composition and a pattern-forming method that can form a resist film that exhibits sufficient levels of sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity, even when forming a high aspect ratio resist pattern. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to solve this problem and, as a result, found that the above objective can be achieved by adopting the following configuration, thus completing the present invention.

[0009] For example, in one embodiment, the present invention The first onium salt compound represented by the following formula (1), The second onium salt compound represented by the following formula (2), A resin containing structural units having acid-dissociable groups, Solvent and This relates to a radiation-sensitive resin composition containing [a specific substance]. [ka] (In formula (1), R 1 It is a monovalent, chain-like organic group having 1 to 40 carbon atoms. R 2 and R 3is, independently of each other, a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group or a monovalent fluorinated hydrocarbon group. R 2 and R 3 When a plurality of them exist, the plurality of R 2 and R 3 are each the same or different. R f11 and R f12 are, independently of each other, a fluorine atom or a monovalent fluorinated hydrocarbon group. R f11 and R f12 When a plurality of them exist, the plurality of R f11 and R f12 are each the same or different. m1 and m2 are, independently of each other, integers from 1 to 4. R 4 、R 5 、R 6 and R 7 are, independently of each other, a hydrogen atom, a hydroxy group, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. R 4 、R 5 、R 6 and R 7 When a plurality of them exist, the plurality of R 4 、R 5 、R 6 and R 7 are each the same or different. R 8 When one R 8 exists, R 8 is a hydrogen atom, a hydroxy group, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. R 8 When a plurality of them exist, R 8 is, independently of each other, a hydrogen atom, a hydroxy group, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, or two of the plurality of R n1 and n2 are, independently of each other, integers from 1 to 4. n3 is an integer from 1 to 5.)

Chemical formula

[0010] The radiation-sensitive resin composition contains both a first onium salt compound and a second onium salt compound as radiation-sensitive acid generators, enabling it to exhibit excellent sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity even when forming high aspect ratio resist patterns. While not bound by any theory, the reason for this is presumed to be as follows: The anionic portion of the first onium salt compound has a chain-like structure, reducing the effect of steric hindrance, resulting in a relatively long diffusion length of the generated acid. This allows the generated acid to spread sufficiently even in thick resist films without uneven distribution. Furthermore, the cation portion of the first onium salt compound has high transparency and high quantum efficiency due to its structure, enabling efficient acid generation across the entire thickness direction during exposure, even in thick resist films. In addition, it has a thioxane-like structure containing sulfur and oxygen, resulting in high solubility and allowing for homogeneous dispersion in the resist film. By combining the unique properties of these first onium salt compounds with those of the second onium salt compound, which has a cyclic structure in its anionic portion and generates an acid with a relatively short diffusion length, the effects of both compounds complement each other, making it possible to impart optimal acid diffusion length, solubility, and acidity to various pattern sizes that are difficult to achieve with a single composition. As a result, the given resist properties can be exhibited. Note that an organic group refers to a group containing at least one carbon atom.

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

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

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

[0014] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises a first onium salt compound, a second onium salt compound, a resin containing structural units having acid-dissociable groups, and a solvent. It further optionally contains an acid diffusion control agent. The above composition may contain other optional components as long as they do not impair the effects of the present invention. By including the first onium salt compound and the second onium salt compound together as a radiation-sensitive acid generator, the radiation-sensitive resin composition can impart a high level of sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity to the resist film of the radiation-sensitive resin composition.

[0015] (First onium salt compound) The first onium salt compound is represented by formula (1) above and functions as a radiation-sensitive acid generator that produces acid upon irradiation with radiation.

[0016] R 1The monovalent linear organic group having 1 to 40 carbon atoms represented by is not particularly limited as long as it has a linear structure. Examples of such linear structures include monovalent linear hydrocarbon groups having 1 to 40 carbon atoms, regardless of whether they are saturated or unsaturated, linear or branched; groups in which some or all of the hydrogen atoms in the linear hydrocarbon group are replaced with substituents; groups containing -CO-, -CS-, -O-, -S-, -SO2-, -NR'-, or a combination of two or more of these at the carbon-carbon intervals or carbon chain ends of these groups; or combinations thereof. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0017] Examples of the above-mentioned chain-like hydrocarbon groups having 1 to 40 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 40 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 40 carbon atoms. Examples of the above-mentioned linear or branched saturated hydrocarbon groups having 1 to 40 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, isopentyl, and neopentyl groups. Examples of linear or branched unsaturated hydrocarbon groups having 1 to 40 carbon atoms include alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0018] Examples of substituents that substitute for some or all of the hydrogen atoms of the above-mentioned chain-like hydrocarbon group include halogen atoms such as fluorine, chlorine, bromine, and iodine; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O).

[0019] Among them, R 1The monovalent linear organic group having 1 to 40 carbon atoms represented by is preferably a monovalent linear hydrocarbon group having 1 to 40 carbon atoms, a group in which at least one of an ether bond (-O-) and a carbonyl group (-CO-) (and therefore including an ester bond) is incorporated in the chain or at the end of the chain of a monovalent linear hydrocarbon group having 1 to 40 carbon atoms, a group in which some or all of the hydrogen atoms of a monovalent linear hydrocarbon group having 1 to 40 carbon atoms are substituted with fluorine atoms, or a combination thereof. Furthermore, a group in which at least one of an ether bond (-O-) and a carbonyl group (-CO-) is incorporated in the chain or at the end of the chain of a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, a group in which some or all of the hydrogen atoms of a monovalent linear hydrocarbon group having 1 to 20 carbon atoms are substituted with fluorine atoms, or a combination thereof. In particular, R 1 The monovalent chain-like organic group having 1 to 40 carbon atoms represented by is preferably a linear organic group having 1 to 40 carbon atoms.

[0020] Groups in which at least one of an ether bond (-O-) and a carbonyl group (-CO-) is incorporated into the chain or at the end of a monovalent linear hydrocarbon group having 1 to 20 carbon atoms include alkoxyalkyl groups, alkylcarbonylalkyl groups, alkoxycarbonylalkyl groups, alkylcarbonyloxyalkyl groups, alkylcarbonyloxy groups, and alkoxy groups. The alkyl chains of these groups are preferably independently having 1 to 12 carbon atoms. At least one of an ether bond (-O-) and a carbonyl group (-CO-) may be repeatedly incorporated into the chain. Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms.

[0021] As a group in which some or all of the hydrogen atoms of the above-mentioned monovalent chain hydrocarbon group having 1 to 20 carbon atoms are substituted with fluorine atoms, a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms is preferred.

[0022] Examples of the above monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms include, for example, Fluorinated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoro-n-propyl group, heptafluoro-i-propyl group, nonafluoro-n-butyl group, nonafluoro-i-butyl group, nonafluoro-t-butyl group, 2,2,3,3,4,4,5,5-octafluoro-n-pentyl group, tridecafluoro-n-hexyl group, and 5,5,5-trifluoro-1,1-diethylpentyl group; Fluorinated alkenyl groups such as trifluoroethenyl groups and pentafluoropropenyl groups; Examples include fluorinated alkynyl groups such as fluoroethynyl groups and trifluoropropynyl groups.

[0023] R 2 and R 3 The monovalent hydrocarbon group represented by the above R is 1 Examples include monovalent chain hydrocarbon groups having 1 to 40 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 40 carbon atoms, or combinations thereof.

[0024] Examples of monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. Examples of monocyclic unsaturated hydrocarbon groups are monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. Examples of polycyclic unsaturated hydrocarbon groups are polycyclic cycloalkenyl groups such as norborneyl, tricyclodecenyl, and tetracyclododecenyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded together by a bond chain containing one or more carbon atoms.

[0025] Examples of monovalent aromatic hydrocarbon groups having 6 to 40 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthyl groups; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0026] R 2 and R 3 The monovalent fluorinated hydrocarbon group represented by the above R is 1 Examples include monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms, as well as monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0027] Examples of the above-mentioned monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms include, for example, Fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, and fluorotricyclodecyl group; Examples include fluorinated cycloalkenyl groups such as fluorocyclopentenyl groups and nonafluorocyclohexenyl groups.

[0028] The above-mentioned fluorinated hydrocarbon group is preferably a monovalent fluorinated linear hydrocarbon group having 1 to 8 carbon atoms, and more preferably a monovalent fluorinated linear hydrocarbon group having 1 to 5 carbon atoms.

[0029] R 2 and R 3 In terms of the degree of freedom of the surrounding structure of the sulfo group and the acidity of the generated acid, hydrogen atoms, fluorine atoms, or monovalent fluorinated linear hydrocarbon groups having 1 to 5 carbon atoms are preferred.

[0030] R f11 and R f12 As a monovalent fluorinated hydrocarbon group represented by , R 2 and R 3A monovalent fluorinated hydrocarbon group represented by can be suitably used.

[0031] m1 and m2 are each independently preferably integers between 1 and 3, more preferably 1 or 2, and particularly preferably 1.

[0032] Specific examples of the anionic moiety of the first onium salt compound include, but are not limited to, the structures shown in formulas (1-1-1) to (1-1-20) below.

[0033] [ka]

[0034] [ka]

[0035] R 4 , R 5 , R 6 and R 7 (Hereinafter referred to as “R 4 ~R 7 ) is also written as ). The monovalent organic group having 1 to 20 carbon atoms represented by ) may be a group corresponding to the structure of 1 to 20 carbon atoms among the monovalent chain organic groups having 1 to 40 carbon atoms mentioned above, a cyclic structure, or a combination thereof. The cyclic structure may be an alicyclic, aromatic, or heterocyclic cyclic hydrocarbon group. The cyclic structure is preferably an alicyclic structure having 3 to 20 carbon atoms, an aromatic cyclic structure having 6 to 20 carbon atoms, or a combination thereof. Other examples include a group in which some or all of the hydrogen atoms contained in the cyclic structure are substituted with substituents, a group containing -CO-, -CS-, -O-, -S-, -SO2-, -NR''- or a combination of two or more of these at the carbon-carbon or carbon chain ends of these groups, or a combination thereof. R'' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0036] A substituent that replaces some or all of the hydrogen atoms of the above organic group is the above R 1 Examples include substituents that substitute for some or all of the hydrogen atoms of the chain-like hydrocarbon group in the above-mentioned compound.

[0037] R 4 ~R 7 As for the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above R 2 and R 3 In this material, monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms can be preferably selected from those having 3 to 20 carbon atoms.

[0038] R 4 ~R 7 In this, the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is the above R 2 and R 3 Among the monovalent aromatic hydrocarbon groups having 6 to 40 carbon atoms, groups corresponding to 6 to 20 carbon atoms can be suitably adopted.

[0039] The above R 4 ~R 7 Examples of heterocyclic cyclic hydrocarbon groups in this context include groups obtained by removing one hydrogen atom from an aromatic heterocyclic structure and groups obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. Aromatic structures with five-membered rings that acquire aromaticity by introducing heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0040] Examples of the above aromatic heterocyclic structures include, for example, Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur atom-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0041] Examples of the above alicyclic heterocyclic structures include, for example, Oxygen atom-containing alicyclic heterocyclic structures such as oxiranes, tetrahydrofurans, tetrahydropyrans, dioxolanes, and dioxanes; Nitrogen-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thiethane, thiolane, and thian; Examples include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0042] Examples of cyclic structures include lactone structures, cyclic carbonate structures, sultone structures, and structures containing cyclic acetals.

[0043] R 8 As a monovalent organic group having 1 to 20 carbon atoms, represented by the above R 4 ~R 7 A monovalent organic group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0044] R 8 When there are multiple R 8 The cyclic structure with 5 to 20 members, formed by combining these elements and bonding them together with the two carbon atoms of the benzene ring in formula (1) above, is R 4 ~R 7 Among the cyclic structures shown, structures corresponding to ring member numbers of 5 to 20 can be suitably adopted. In particular, as a cyclic structure, a alicyclic hydrocarbon structure with 5 to 20 carbon atoms is preferred from the viewpoint of the transparency of the cation portion of the first onium salt compound. As for the alicyclic hydrocarbon structure with 5 to 20 carbon atoms, R 4 ~R 7 Examples of structures corresponding to C5-C20 of the monovalent alicyclic hydrocarbon groups with C3-C20 shown above include the C5-C20 structure.

[0045] R 4 , R 5 , R 6 , R 7 and R8 Preferably, these are a hydrogen atom, a halogen atom, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. Among these, R 4 , R 5 , R 6 and R 7 is a hydrogen atom, and R 8 It is more preferable that the carbon atom is a chain-like hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 6 to 12 carbon atoms, a fluorine atom, or a fluorinated hydrocarbon group having 1 to 10 carbon atoms. Preferred monovalent chain-like hydrocarbon groups having 1 to 10 carbon atoms include methyl, ethyl, isopropyl, tert-butyl, and 1,1-dimethyl-1-propyl groups. Preferred monovalent alicyclic hydrocarbon groups having 6 to 12 carbon atoms include cyclohexyl and cycloheptyl groups. Preferred fluorinated hydrocarbon groups having 1 to 10 carbon atoms include trifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, 2,2,3,3,3-pentafluoropropyl, 1,1,1,3,3,3-hexafluoropropyl, and heptafluoro-n-propyl groups.

[0046] n1 and n2 are each independently preferably integers between 2 and 4, and more preferably 2 or 3. n3 is preferably an integer between 1 and 4, more preferably an integer between 1 and 3, and even more preferably 1 or 2.

[0047] Specific examples of the cation moiety of the first onium salt compound include, but are not limited to, the structures shown in formulas (1-2-1) to (1-2-24) below.

[0048] [ka]

[0049] The first onium salt compound can be obtained by appropriately combining the above-mentioned anionic and cationic moieties. Specific examples, though not limited to them, include structures such as those shown in formulas (1-1) to (1-22) below.

[0050] [Chemical formula]

[0051] [Chemical formula]

[0052] (When including a plurality of types of the first onium salt compounds, the lower limit of the content of the first onium salt compound (the total thereof) is preferably 0.1 part by mass, more preferably 1 part by mass, still more preferably 3 parts by mass, and particularly preferably 5 parts by mass with respect to 100 parts by mass of the resin described later. The upper limit of the above content is preferably 100 parts by mass, more preferably 80 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass. The content of the first onium salt compound is appropriately selected according to the type of resin used, exposure conditions, required sensitivity, etc. Thereby, excellent sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity can be exhibited during resist pattern formation.)

[0053] (Synthesis method of the first onium salt compound) As a synthesis method of the first onium salt compound, in the above formula (1), R 4 , R 5 , R 6 and R 7 are hydrogen atoms, n1 and n2 are both 2, and the case where n3 is 1 will be described as an example. A representative scheme is shown below.

[0054] [Chemical formula] (In the scheme, R 1 , R 2 , R 3 , R f11 , R f12 , m1, m2 and R 8 are synonymous with the above formula (1). M + is a monovalent metal ion.)

[0055] The (substituted)benzene ring is iodinated under acid catalysis, and the iodonium salt is obtained by oxidation of the (substituted)iodobenzene with a peroxide and subsequent iodine oxide elimination reaction. This is then subjected to a nucleophilic substitution reaction with a thioxane or its analog to generate the cation moiety of the first onium salt compound represented by formula (ia). Finally, the first onium salt compound represented by formula (1') can be synthesized by salt exchange with a sulfonate having the structure of the anionic moiety of the first onium salt compound. Other structures can also be synthesized by appropriately selecting the starting materials, thioxane analogs, and sulfonates.

[0056] (Second onium salt compound) The second onium salt compound is represented by formula (2) above and functions as a radiation-sensitive acid generator that produces acid upon irradiation with radiation.

[0057] R B The monovalent organic group having 3 to 40 carbon atoms and containing a cyclic structure represented by is not particularly limited and may be a group containing only a cyclic structure or a group combining a cyclic structure and a chain structure. The cyclic structure may be monocyclic or polycyclic. Furthermore, the cyclic structure may be an aromatic ring structure, an alicyclic structure, a heterocyclic structure, or a combination thereof. The heterocyclic structure includes lactone structures, cyclic carbonate structures, sultone structures, or combinations thereof. These structures are preferably included as the smallest basic skeleton of the cyclic structure. The number of cyclic structures as the basic skeleton in the organic group may be one or two or more. Heteroatoms or heteroatom-containing groups may be interposed between carbon atoms or at the ends of carbon chains forming the skeleton of the cyclic or chain structure, and hydrogen atoms on carbon atoms of the cyclic or chain structure may be substituted with other substituents.

[0058] The above-mentioned annular structure is R 4 , R 5 , R 6 , R 7 and R 8 The above-mentioned cyclic structure can be suitably adopted. Furthermore, as the chain-like structure, the above-mentioned R 1A monovalent, chain-like organic group having 1 to 40 carbon atoms, represented by , can be suitably used. Examples of the heteroatom or heteroatom-containing group include groups containing -CO-, -CS-, -O-, -S-, -SO2-, -NR'''-, or combinations of two or more of these. R''' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Substituents that replace hydrogen atoms on carbon atoms in the above cyclic or chain-like structure include the above R 1 Examples include substituents that substitute for some or all of the hydrogen atoms of the chain-like hydrocarbon group in the above-mentioned compound.

[0059] R B The cyclic structure contained in is preferably an alicyclic polycyclic structure having 6 to 14 carbon atoms, and more preferably a norbornyl group or an adamantyl group.

[0060] R f21 and R f22 The monovalent fluorinated hydrocarbon group represented by the above R is f11 and R f12 A monovalent fluorinated hydrocarbon group represented by can be suitably used.

[0061] p is preferably an integer between 1 and 3, and more preferably 1 or 2.

[0062] Specific examples of the anionic moiety of a second onium salt compound include, but are not limited to, the structures shown in formulas (2-1-1) to (2-1-30) below.

[0063] [ka]

[0064] [ka]

[0065] In the above equation (2), the above Z +Examples of monovalent radiosensitive onium cations represented by the formulas (X-1) to (X-6) below include radiodegradable onium cations containing, for example, elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, along with the cation portion of the first onium salt compound. Examples of radiodegradable onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, sulfonium cations or iodonium cations are preferred. Sulfonium cations or iodonium cations are preferably represented by the following formulas (X-1) to (X-6).

[0066] [ka]

[0067] In the above equation (X-1), R a1 Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxyl group, a halogen atom, and -OSO2-R. P , -SO2-R Q Alternatively, -SR T This represents a ring structure formed by combining two or more of these groups. This ring structure may contain heteroatoms such as O or S between the carbon-carbon bonds that form the skeleton. P , R Q and R T Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently integers from 0 to 5. a1 R P , R Q and R TIf each of them is multiple, then multiple R a1 R P , R Q and R T These may be the same or different.

[0068] In the above equation (X-2), R b1 This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. k n is either 0 or 1. k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer from 0 to 7. b1 If there are multiple, then multiple R b1 They may be the same or different, and there may be multiple R b1 R may represent a ring structure formed by combining with other elements. b2 This is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. b2 If there are multiple, then multiple R b2 They may be the same or different, and there may be multiple R b2 may represent a ring structure formed by combining with each other. q is an integer between 0 and 3. In the formula, S + The ring structure containing may include heteroatoms such as O and S between the carbon-carbon bonds that form the skeleton.

[0069] In the above equation (X-3), R c1 , R c2 and R c3 Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0070] In the above equation (X-4), R g1This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. k n is either 0 or 1. k2 When k10 is 0, k10 is an integer from 0 to 4, and n k2 When k10 is 1, k10 is an integer from 0 to 7. g1 If there are multiple, then multiple R g1 They may be the same or different, and there may be multiple R g1 R may represent a ring structure formed by combining with other elements. g2 is and R g3 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R g2 is and R g3 If each of them is multiple, then multiple R g2 is and R g3 These may be the same or different.

[0071] In the above equation (X-5), R d1 and R d2 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by two or more of these groups being combined. k6 and k7 are each independently integers from 0 to 5. d1 and R d2 If each of them is multiple, then multiple R d1 and R d2 These may be the same or different.

[0072] In the above equation (X-6), R e1 and R e2 k8 and k9 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0073] Specific examples of the above-mentioned radiation-sensitive onium cation include, but are not limited to, structures such as those shown in formulas (2-2-1) to (2-2-32) below.

[0074] [ka]

[0075] [ka]

[0076] Examples of secondary onium salt compounds include structures obtained by arbitrarily combining the above-mentioned anionic moiety and the above-mentioned radiation-sensitive onium cation. Specific examples of secondary onium salt compounds, though not limited to them, include onium salt compounds represented by the following formulas (2-1) to (2-30).

[0077] [ka]

[0078] [ka]

[0079] The lower limit of the content of the second onium salt compound (total of multiple types of second onium salt compounds if included) is preferably 1 part by mass, more preferably 2 parts by mass, even more preferably 3 parts by mass, and particularly preferably 4 parts by mass per 100 parts by mass of the resin described later. The upper limit of the above content is preferably 40 parts by mass, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass. The content of the second onium salt compound is appropriately selected depending on the type of resin used, exposure conditions, and the required sensitivity. This enables excellent sensitivity, CDU performance, pattern circularity, LWR performance, and pattern rectangularity during resist pattern formation.

[0080] The lower limit of the mass-based ratio b / a of the content b of the second onium salt compound to the content a of the first onium salt compound is preferably 0.05, more preferably 0.1, even more preferably 0.2, and particularly preferably 0.5. The upper limit of the ratio b / a is preferably 20, more preferably 15, even more preferably 10, and particularly preferably 5.

[0081] (resin) The resin is an aggregate of polymers containing structural units having acid-dissociable groups (hereinafter also referred to as "structural unit (I)") (hereinafter this resin is also referred to as the "base resin"). An "acid-dissociable group" is a hydrogen atom-substituting group such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group, which dissociates upon the action of an acid. The radiation-sensitive resin composition exhibits excellent pattern-forming properties because the resin contains structural unit (I).

[0082] The base resin preferably contains structural unit (II), which includes at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures, as described later, in addition to structural unit (I). It may also contain other structural units other than structural units (I) and (II). Each structural unit will be described below.

[0083] [Structural Unit (I)] Structural unit (I) is a structural unit containing an acid-dissociable group. Structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is replaced by a tertiary alkyl group, and a structural unit having an acetal bond. However, from the viewpoint of improving the pattern-forming properties of the radiation-sensitive resin composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0084] [ka]

[0085] In the above equation (3), R 17 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 18 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 19 and R 20 Each of these independently represents either a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups with the carbon atoms to which they are bonded.

[0086] The above R 17 From the viewpoint of copolymerization of the monomer that gives structural unit (I-1), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0087] The above R 18 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include chain hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0088] The above R 18 ~R 20 Examples of chain-like hydrocarbon groups having 1 to 10 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.

[0089] The above R 18 ~R 20 As an example of an alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (1), R 2 and R 3 In this material, monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms can be preferably selected from those having 3 to 20 carbon atoms.

[0090] The above R 18 As a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the above formula (1), R 2 and R 3 Among the monovalent aromatic hydrocarbon groups having 6 to 40 carbon atoms, groups corresponding to those with 3 to 20 carbon atoms can be suitably adopted.

[0091] The above R 18 Preferred carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0092] The above R 19 and R 20 A divalent alicyclic group having 3 to 20 carbon atoms, formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by the above formula with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon of the above carbon number. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and as a polycyclic hydrocarbon group, it may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. A condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

[0093] Among monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1 3,7 A decane-2,2-diyl group (adamantane-2,2-diyl group) is preferred.

[0094] Among these, R 18 R is an alkyl group having 1 to 4 carbon atoms. 19 and R 20 It is preferable that the alicyclic structure formed by combining these elements with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0095] Examples of structural units (I-1) include the structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0096] [ka]

[0097] In the above equations (3-1) to (3-6), R 17 ~R 20 This is equivalent to equation (3) above. i and j are independent integers between 1 and 4. k and l are 0 or 1.

[0098] i and j are preferably 1. 18 As such, a methyl group, ethyl group, isopropyl group, or cyclopentyl group is preferred. 19 and R 20 A methyl group or an ethyl group is preferred.

[0099] The base resin may contain one or more structural units (I) in combination.

[0100] The lower limit of the content of structural unit (I) (total content if multiple types are included) is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%, relative to the total structural units constituting the base resin. The upper limit of the above content is preferably 80 mol%, more preferably 75 mol%, even more preferably 70 mol%, and particularly preferably 65 mol%. By setting the content of structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive resin composition can be further improved.

[0101] [Structural Units (II)] Structural unit (II) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising structural unit (II), the solubility of the base resin in the developer can be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0102] Examples of structural units (II) include those represented by the following formulas (T-1) to (T-10).

[0103] [ka]

[0104] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group.L4 and R L5 These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and formed together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0105] The above R L4 and R L5 When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms that is formed together with the carbon atoms to which they are bonded is R in formula (3) above. 19 and R 20 Examples include divalent alicyclic groups with 3 to 8 carbon atoms, which are formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by , together with the carbon atoms to which they are bonded. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0106] The above L 2 Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0107] Among these, structural units (II) are preferably those containing a lactone structure, more preferably those containing a norbornane lactone structure, and even more preferably those derived from norbornane lactone-yl (meth)acrylate.

[0108] The lower limit of the content of structural unit (II) is preferably 20 mol%, more preferably 30 mol%, and even more preferably 35 mol%, relative to the total structural units constituting the base resin. The upper limit of the content is preferably 75 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By setting the content of structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0109] [Structural Unit (III)] The base resin may optionally contain other structural units in addition to the structural units (I) and (II) described above. Examples of these other structural units include structural unit (III) containing a polar group (excluding those corresponding to structural unit (II)). By further containing structural unit (III), the solubility of the base resin in the developer can be adjusted, and as a result, the lithographic performance such as resolution of the radiation-sensitive resin composition can be improved. Examples of these polar groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and sulfonamide groups. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.

[0110] Examples of structural units (III) include structural units represented by the following formula.

[0111] [ka]

[0112] In the above formula, R A This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0113] When the base resin has structural unit (III) having the polar group, the lower limit of the content of structural unit (III) is preferably 5 mol%, more preferably 8 mol%, and even more preferably 10 mol%, relative to the total structural units constituting the base resin. The upper limit of the content is preferably 40 mol%, more preferably 35 mol%, and even more preferably 30 mol%. By setting the content of structural unit (III) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0114] [Structural Units (IV)] The base resin may optionally contain structural units other than the polar group-containing structural unit (III) described above, such as structural units derived from hydroxystyrene or structural units containing phenolic hydroxyl groups (hereinafter, both are collectively referred to as "structural unit (IV)"). Structural unit (IV) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelengths of 50 nm or less, such as electron beams and EUV. In this case, it is preferable that the resin contains structural unit (I) along with structural unit (IV).

[0115] Structural units derived from hydroxystyrene are represented, for example, by formulas (4-1) to (4-2) below, and structural units having a phenolic hydroxyl group are represented, for example, by formulas (4-3) to (4-4) below.

[0116] [ka]

[0117] In the above equations (4-1) to (4-4), R 11 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0118] When obtaining structural unit (IV), it is preferable to polymerize the phenolic hydroxyl group while protecting it with a protecting group such as an alkali-dissociable group (e.g., an acyl group), and then deprotect it by hydrolysis to obtain structural unit (IV).

[0119] For resins used for exposure with radiation of wavelength 50 nm or less, the lower limit of the content of structural unit (IV) is preferably 10 mol%, and more preferably 20 mol%, relative to the total structural units constituting the resin. The upper limit of the above content is preferably 70 mol%, and more preferably 60 mol%.

[0120] (Method of synthesizing the base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0121] Examples of the radical polymerization initiators mentioned above 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), and dimethyl-2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl-2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used individually or in combination of two or more.

[0122] Examples of solvents used in the polymerization described above include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 2-butanone, 4-methyl-2-pentanone, and 2-heptanone; Ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. The solvent used in these polymerizations may be used alone or in combination of two or more.

[0123] The reaction temperature in the polymerization described above is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0124] The molecular weight of the base resin is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 4,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, even more preferably 15,000, and particularly preferably 12,000. If the Mw of the base resin is below the above lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the base resin exceeds the above upper limit, the developability of the resist film may decrease.

[0125] The ratio of Mw (Mw / Mn) to the polystyrene-equivalent number-average molecular weight (Mn) of the base resin, calculated by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0126] In this specification, the Mw and Mn values ​​of the resin are measured using gel permeation chromatography (GPC) under the following conditions.

[0127] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Leaching solvent: Tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0128] The base resin content is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, relative to the total solid content of the radiation-sensitive resin composition.

[0129] (Other resins) The radiation-sensitive resin composition of this embodiment may also contain, as another resin, a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface of the resist film relative to the base resin, and as a result, the water repellency of the surface of the resist film during immersion exposure can be improved.

[0130] The high-fluorine-content resin preferably has a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may optionally have structural unit (I) or structural unit (III) of the base resin.

[0131] [ka]

[0132] In the above equation (5), R 13 This is a hydrogen atom, a methyl group, or a trifluoromethyl group. LR is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. 14 This is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0133] The above R 13 From the viewpoint of copolymerization of monomers that provide structural unit (V), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0134] The above G L From the viewpoint of copolymerization of monomers that provide structural unit (V), single bonds and -COO- are preferred, and -COO- is more preferred.

[0135] The above R 14 Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0136] The above R 14 Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0137] The above R 14 Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0138] When a high-fluorine-content resin has structural units (V), the content of structural units (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, it is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less. By setting the content of structural units (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting the uneven distribution to the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0139] High-fluorine content resins may have fluorine atom-containing structural units (hereinafter also referred to as structural unit (VI)) represented by the following formula (f-2), either together with or in place of structural unit (V). The presence of structural unit (f-2) in high-fluorine content resins improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0140] [ka]

[0141] Structural units (VI) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates upon the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D This is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and the R of this hydrocarbon group E At the terminal end of the side are an oxygen atom, a sulfur atom, and -NR dd -, a structure to which a carbonyl group, -COO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are replaced by an organic group having a heteroatom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0142] If structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, A 1 * is an oxygen atom, -COO-* or -SO2O-*. F This shows the binding site. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 If is an oxygen atom, then W 1 is A 1 It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. E is a single bond or a divalent organic group with 1 to 20 carbon atoms. If s is 2 or 3, there are multiple R E , W 1 , A 1 and R F These may be the same or different. Having (x) an alkali-soluble group in structural unit (VI) increases its affinity for alkaline developer and suppresses development defects. A structural unit (VI) having (x) an alkali-soluble group is A 1 is an oxygen atom and W 1 It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0143] If structural unit (VI) has an alkali-dissociable group (y), R F A is a monovalent organic group having 1 to 30 carbon atoms. 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-* aa * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. F This shows the binding site. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 If is -COO-* or -SO2O-*, then W 1or R F is A 1 It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. 1 If is an oxygen atom, then W 1 , R E It is a single bond, R D R is a hydrocarbon group with 1 to 20 carbon atoms. E It is a structure in which a carbonyl group is bonded to the terminal end, R F is an organic group containing a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F These may be the same or different. The presence of (y) an alkali-dissociable group in structural unit (VI) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural unit (VI) having (y) an alkali-dissociable group include A 1 is -COO-*, R F Or W 1 Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0144] R C From the viewpoint of copolymerizability of the monomer that gives structural unit (VI), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0145] R E When the group is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is even more preferred.

[0146] When the high-fluorine content resin has the structural unit (VI), the content ratio of the structural unit (VI) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more with respect to all the structural units constituting the high-fluorine content resin. Further, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content ratio of the structural unit (VI) within the above range, the water repellency of the resist film during liquid immersion exposure can be further improved.

[0147] [Other structural units] The high-fluorine content resin may contain, as structural units other than the above-listed structural units, a structural unit having an alicyclic structure represented by the following formula (6). [Chemical formula] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0148] In the above formula (6), as the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R 2α , the groups corresponding to 3 to 20 carbon atoms among the monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms in R 2 and R 3 in the above formula (1) can be preferably adopted.

[0149] When the high-fluorine content resin contains a structural unit having the above alicyclic structure, the content ratio of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more with respect to all the structural units constituting the high-fluorine content resin. Further, it is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less.

[0150] The lower limit of Mw for the high-fluorine-content resin is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, and particularly preferably 15,000.

[0151] The Mw / Mn ratio of high-fluorine-content resins is usually 1 or higher, more preferably 1.1 or higher. It is also usually 5 or lower, preferably 3 or lower, more preferably 2 or lower, and even more preferably 1.9 or lower.

[0152] The content of the high-fluorine resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0153] By setting the content of the high-fluorine-content resin within the above range, the high-fluorine-content resin can be more effectively distributed to the surface layer of the resist film, and as a result, the water repellency of the surface of the resist film during immersion exposure can be further enhanced. The radiation-sensitive resin composition may contain one or more high-fluorine-content resins.

[0154] (Method for synthesizing high-fluorine content resins) High-fluorine-content resins can be synthesized by the same method as the base resin synthesis method described above.

[0155] (Acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion control agent. The acid diffusion control agent controls the diffusion phenomenon of acids generated from the first and second onium salt compounds in the resist film upon exposure, thereby suppressing undesirable chemical reactions in the unexposed areas. Furthermore, it improves the storage stability of the resulting radiation-sensitive resin composition. In addition, it further improves the resolution of the resist pattern and suppresses changes in the line width of the resist pattern due to variations in the holding time from exposure to development, resulting in a radiation-sensitive resin composition with excellent process stability.

[0156] Examples of acid diffusion control agents include compounds represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compounds (I)"), compounds having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compounds (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compounds (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

[0157] [ka]

[0158] In equation (7) above, R 22 , R 23 and R 24 Each of these is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0159] Examples of nitrogen-containing compounds (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0160] Examples of nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0161] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethyl acrylamide and the like.

[0162] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like.

[0163] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like.

[0164] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole and the like.

[0165] Also, as the above 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-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-butoxycarbonyl-4-acetoxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine and the like.

[0166] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can be suitably used as an acid diffusion control agent. The acid generated by the above-mentioned radiation-sensitive acid generator is a weak acid that does not induce the dissociation of the acid-dissociable groups in the resin under conditions that would normally cause the dissociation of those groups. In this specification, "dissociation" of an acid-dissociable group refers to dissociation that occurs when post-exposure baking is performed at 110°C for 60 seconds.

[0167] Examples of radiation-sensitive weak acid generators include onium salt compounds that decompose upon exposure and lose their ability to control acid diffusion. Examples of onium salt compounds include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2).

[0168] [ka]

[0169] In the above equations (8-1) and (8-2), J + It is a sulfonium cation, U + This is an iodonium cation. + Examples of sulfonium cations represented by the above formulas (X-1) to (X-3) include U + Examples of iodonium cations represented by the above formulas (X-4) to (X-5) include iodonium cations represented by E - and Q - Each of them is independent of OH - , R α -COO - , R α -SO3 - This is an anion represented by R. α This refers to a monovalent, chain-like organic group having 1 to 40 carbon atoms, or a monovalent organic group having 3 to 40 carbon atoms that includes a cyclic structure. α As a monovalent chain-like organic group having 1 to 40 carbon atoms, R in formula (1) above is an example. 1 A monovalent, chain-like organic group having 1 to 40 carbon atoms, represented by R, can be suitably used. αAs a monovalent organic group having 3 to 40 carbon atoms, R in formula (2) above is an example. B A monovalent organic group having 3 to 40 carbon atoms and containing a cyclic structure represented by [the formula shown] can be suitably used.

[0170] Examples of the above-mentioned radiation-sensitive weak acid generating agent include compounds represented by the following formula.

[0171] [ka]

[0172] [ka]

[0173] Among the above-mentioned radiation-sensitive weak acid generating agents, sulfonium salts are preferred, triarylsulfonium salts are more preferred, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are even more preferred.

[0174] The lower limit of the acid diffusion control agent content is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 2 parts by mass, per 100 parts by mass of the resin. The upper limit of the above content is preferably 20 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass.

[0175] By setting the content of the acid diffusion control agent within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion control agents.

[0176] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least compound (1) and the resin, as well as optionally contained radiation-sensitive acid generators, etc.

[0177] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0178] Examples of alcohol-based solvents include, Monoalcohol solvents with 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Polyhydric alcohol solvents with 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partial ether solvents, in which some of the hydroxyl groups of the above-mentioned polyhydric alcohol solvents have been etherified.

[0179] Examples of ether-based solvents include, Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether); Examples include polyhydric alcohol ether solvents, which are obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0180] Examples of ketone solvents include chain-like ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0181] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples include chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0182] Examples of ester-based solvents include, Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; Polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone-based solvents such as γ-butyrolactone and valerolactone; Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polycarboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0183] Examples of hydrocarbon solvents include, for example, Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0184] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0185] (Other optional components) The above-mentioned radiation-sensitive resin composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, segregation promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used individually or in combination of two or more types.

[0186] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a first onium salt compound, a second onium salt compound, a resin, and optionally a high-fluorine-content resin, as well as a solvent, in predetermined proportions. After mixing, the above radiation-sensitive resin composition is preferably filtered using a filter with a pore size of approximately 0.05 μm to 0.40 μm. The solid content concentration of the above radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0187] The lower limit of the viscosity of the above radiation-sensitive resin composition is preferably 1.0 mPa·s, more preferably 1.2 mPa·s, and even more preferably 1.4 mPa·s. The upper limit of the viscosity is preferably 15 mPa·s, more preferably 10 mPa·s, and even more preferably 5 mPa·s.

[0188] <Pattern Formation Method> A pattern forming method according to one embodiment of the present invention is: The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film formation step"), The above resist film is exposed in step (2) (hereinafter also referred to as the "exposure step"), The process includes (3) developing the exposed resist film (hereinafter also referred to as the "development step").

[0189] According to the above resist pattern formation method, a high-quality resist pattern can be formed because it uses the above-mentioned radiation-sensitive resin composition, which is capable of forming a resist film with excellent sensitivity in the exposure process, LWR performance, CDU performance, pattern rectangularity, and etching resistance. The following describes each step.

[0190] [Resist film formation process] In this step (step (1) above), a resist film is formed using the radiation-sensitive resin composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods for forming the resist film include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, with 80°C to 120°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0191] The lower limit of the thickness of the formed resist film is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the thickness is preferably 500 nm, more preferably 400 nm, and even more preferably 300 nm. In particular, when a thick resist film is exposed to ArF excimer laser light in the exposure process described later, the lower limit of the thickness may be 100 nm, 150 nm, or 200 nm.

[0192] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content resin in the above-mentioned radiation-sensitive resin composition, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0193] Furthermore, when the subsequent exposure process is carried out with radiation of a wavelength of 50 nm or less, it is preferable to use a resin having the above structural units (I) and (IV) as the base resin in the above composition.

[0194] [Synthesis process] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion medium such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0195] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorinated inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0196] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the resin, etc., by the acid generated from the radiation-sensitive acid generator during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0197] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0198] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0199] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0200] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate choice can be made depending on whether a positive or negative pattern is desired.

[0201] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling the developer solution onto the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution onto a substrate rotating at a constant speed while scanning the developer solution dispensing nozzle at a constant speed (dynamic dispensing method). [Examples]

[0202] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0203] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured Mw and Mn values.

[0204] [ 13 C-NMR analysis] polymer 13 ¹

[0205] <Synthesis of resins> The monomers used in the synthesis of each resin in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0206] [ka]

[0207] [Synthesis Example 1] (Synthesis of resin (A-1)) Monomers (M-1), (M-2), and (M-13) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% of the total monomers used, 100 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdered resin (A-1) (yield: 83%). The Mw of resin (A-1) was 8,800, and the Mw / Mn ratio was 1.50. 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-2), and (M-13) was 41.3 mol%, 13.8 mol%, and 44.9 mol%, respectively.

[0208] [Synthesis Examples 2-11] (Synthesis of resins (A-2) to (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the monomers used were of the types and proportions shown in Table 1 below. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0209] [Table 1]

[0210] (Synthesis of resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the resin. The obtained solid was filtered off and dried at 50°C for 13 hours to obtain a white powdered resin (A-12) (yield: 79%). The Mw of resin (A-12) was 5,200, and the Mw / Mn ratio was 1.60. 13 1C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-18) was 51.3 mol% and 48.7 mol%, respectively.

[0211] [Synthesis Examples 13-15] (Synthesis of resin (A-13) to resin (A-15)) Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the monomers used were of the types and proportions shown in Table 2 below. Note that all monomers that yielded structural unit (IV) had their alkali-dissociable groups hydrolyzed to phenolic hydroxyl groups. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit in the obtained resins are also shown in Table 2 below.

[0212] [Table 2]

[0213] [Synthesis Example 16] (Synthesis of high-fluorine content resin (F-1)) Monomer (M-1) and monomer (M-20) were dissolved in 200 parts by mass of 2-butanone to a molar ratio of 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 200 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine content resin (F-1) was obtained (yield: 69%). The Mw of the high-fluorine-content resin (F-1) was 6,000, and the Mw / Mn ratio was 1.62. Furthermore, 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-20) was 19.9 mol% and 80.1 mol%, respectively.

[0214] [Synthesis Examples 17-20] (Synthesis of high-fluorine content resins (F-2) to high-fluorine content resins (F-5)) High-fluorine-content resins (F-2) to (F-5) were synthesized in the same manner as in Synthesis Example 16, except that monomers of the types and proportions shown in Table 3 below were used. The content percentage (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine-content resins are shown in accordance with Table 3 below.

[0215] [Table 3]

[0216] <Synthesis of the first onium salt compound B> [Synthesis Example 21] (Synthesis of compound (B-1)) Compound (B-1) was synthesized according to the following synthesis scheme.

[0217] [ka]

[0218] 20.0 mmol of iodine, 40.0 mmol of tert-butylbenzene, 40.0 mmol of metachloroperbenzoic acid, 40.0 mmol of tosylic acid monohydrate, and 100 g of chloroform were added to a reaction vessel and stirred at room temperature for 24 hours. After dilution with water, methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated aqueous sodium chloride solution. After drying over sodium sulfate, the solvent was removed by distillation, and the iodonium salt compound was obtained in good yield by recrystallization with diethyl ether.

[0219] 20.0 mmol of 1,4-thioxane, 2.00 mmol of copper(II) acetate, and 50 g of chloroform were added to the iodonium salt and the mixture was stirred under ice for 24 hours. After removing impurities by Celite filtration, the solvent was removed by distillation, and the mixture was purified by column chromatography to obtain compound (B-1-a) represented by the above formula (B-1-a) in good yield.

[0220] To the salt represented by the above formula (B-1-a), 20.0 mmol of potassium nonafluoro-1-butanesulfonate was added, and a mixture of water and dichloromethane (1:1 by mass) was added to prepare a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the compound (B-1) represented by the above formula (B-1) was purified by column chromatography to obtain compound (B-1) in good yield.

[0221] [Synthesis Examples 22-27] (Synthesis of compounds (B-2) to (B-7)) The first onium salt compounds represented by the following formulas (B-2) to (B-7) were synthesized in the same manner as in Synthesis Example 21, except that the raw materials and precursors were changed as appropriate.

[0222] [ka]

[0223] [Synthesis Example 28] (Synthesis of compound (B-8)) Compound (B-8) was synthesized according to the following synthesis scheme.

[0224] [ka]

[0225] 20.0 mmol of 6-bromo-5,5,6,6-tetrafluorohexane-1-ol was mixed with acetonitrile and water (1:1 by mass) to make a 1 M solution. Then, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the mixture was reacted at 70°C for 4 hours. After extraction with acetonitrile and removal of the solvent, a mixture of acetonitrile and water (3:1 by mass) was added to make a 0.5 M solution. 60.0 mmol of hydrogen peroxide and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50°C for 12 hours. A sodium sulfonate salt compound was obtained by extraction with acetonitrile and removal of the solvent. 20.0 mmol of the salt represented by the above formula (B-1-a) was added to the above sodium sulfonate salt compound, and a mixture of water and dichloromethane (1:3 by mass) was added to make a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the onium salt was purified by column chromatography in good yield.

[0226] 20.0 mmol of lauric acid, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride were added to the above onium salt and stirred at room temperature for 3 hours. After dilution with water, methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the compound (B-8) represented by the above formula (B-8) was obtained in good yield by column chromatography.

[0227] [Synthesis Examples 29-37] (Synthesis of compounds (B-9) to (B-17)) The first onium salt compounds represented by the following formulas (B-9) to (B-17) were synthesized in the same manner as in Synthesis Example 28, except that the raw materials and precursors were changed as appropriate.

[0228] [ka]

[0229] [Onium salts other than the first onium salt compounds (B-1) to (B-17)] b-1 to b-5: Compounds represented by the following formulas (b-1) to (b-5) (Hereafter, compounds represented by formulas (b-1) to (b-5) may be referred to as "compound (b-1)" to "compound (b-5)," respectively.)

[0230] [ka]

[0231] [Second onium salt compounds (C-1)~(C-15)] (C-1)~(C-15): Compounds represented by the following formulas (C-1)~(C-15) (Hereafter, compounds represented by formulas (C-1)~(C-15) may be referred to as "compound (C-1)" to "compound (C-15)," respectively.)

[0232] [ka]

[0233] [[D] Acid diffusion control agent] D-1 to D-10: Compounds represented by the following formulas (D-1) to (D-10) and d-1 to d-9: Compounds represented by the following formulas (d-1) to (d-9).

[0234] [ka]

[0235] [ka]

[0236] [[E] Solvent] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-Butyrolactone E-4: Ethyl lactate

[0237] [Preparation of positive-type radiation-sensitive resin composition for ArF exposure] [Example 1] A radiation-sensitive resin composition (J-1) was prepared by mixing [A] 100 parts by mass of (A-1) as a resin, [B] 6.0 parts by mass of (B-1) as a first onium salt compound, [C] 6.0 parts by mass of (C-1) as a second onium salt compound, [D] 6.0 parts by mass of (D-1) as an acid diffusion control agent, [F] 3.0 parts by mass (solids) of (F-1) as a high fluorine-content resin, and [E] 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0238] [Examples 2-65 and Comparative Examples 1-10] Radiation-sensitive resin compositions (J-2) to (J-65) and (CJ-1) to (CJ-10) were prepared in the same manner as in Example 1, except that the components used were of the types and in the amounts shown in Tables 4-1 and 4-2 below.

[0239]

Table 4-1

[0240]

Table 4-2

[0241] [Viscosity Measurement] The viscosity (mPa·s) of the radiation-sensitive resin composition was measured at 25 °C using a Cannon-Fenske viscometer.

[0242] [Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for ArF Exposure] On a 12-inch silicon wafer, using a spin coater (「CLEAN TRACK ACT12」 from Tokyo Electron Limited), a composition for forming an anti-reflection film (「ARC66」 from Brewer Science) was applied, and then heated at 205 °C for 60 seconds to form an anti-reflection film with an average thickness of 100 nm. Using the above spin coater, the prepared positive-type radiation-sensitive resin composition for ArF exposure was applied onto this anti-reflection film, and PB (pre-bake) was performed at 100 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 160 nm was formed. Next, for this resist film, using an ArF excimer laser immersion exposure apparatus (「TWINSCAN XT-1900i」 from ASML), under the optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6), exposure was performed through a mask pattern of contact holes with 80 nm holes and 150 nm pitch. After exposure, PEB (post-exposure bake) was performed at 100 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (contact hole pattern with 80 nm holes and 150 nm pitch).

[0243] [Evaluation] The sensitivity, CDU performance, and pattern circularity of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure were evaluated according to the following methods. The results are shown in Tables 5-1 and 5-2 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0244] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure, the exposure amount used to form 80 nm holes and 150 nm pitch contact holes is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 30 mJ / cm². 2 The following cases are considered "good" and 30 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0245] [CDU performance] The optimal exposure dose determined in the sensitivity evaluation above was used to form 80 nm holes and 150 nm pitch contact holes. The formed resist pattern was observed from the top using the scanning electron microscope described above. The variation of the contact holes was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as CDU (nm). A smaller CDU value indicates less roughness and better performance of the holes. CDU performance was evaluated as "good" if it was less than 5.0 nm and "poor" if it was 5.0 nm or greater.

[0246] [Circular Pattern] The 80nm holes and 150nm pitch contact holes formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above were observed using the scanning electron microscope described above. The vertical and horizontal sizes were measured, and the ratio of vertical size to horizontal size was evaluated as "A" (excellent) if it was 0.95 or more and less than 1.05, "B" (good) if it was 0.90 or more and less than 0.95, or 1.05 or more and less than 1.10, and "C" (poor) if it was less than 0.90 or greater than 1.10.

[0247] [Table 5-1]

[0248] [Table 5-2]

[0249] As is clear from the results in Tables 5-1 and 5-2, the radiation-sensitive resin composition of the example showed good sensitivity, CDU performance, and pattern circularity when used in ArF exposure, whereas the comparative example exhibited inferior characteristics compared to the example. Therefore, when the radiation-sensitive resin composition of the example is used in ArF exposure, it is possible to form a resist pattern with high sensitivity, good CDU performance, and good pattern circularity.

[0250] [Preparation of positive-type radiation-sensitive resin compositions for extreme ultraviolet (EUV) exposure] [Example 66] A radiation-sensitive resin composition (J-66) was prepared by mixing [A] 100 parts by mass of (A-12) as a resin, [B] 9.0 parts by mass of (B-1) as a first onium salt compound, [C] 9.0 parts by mass of (C-1) as a second onium salt compound, [D] 3.0 parts by mass of (D-5) as an acid diffusion control agent, [F] 3.0 parts by mass of (F-5) as a high fluorine-content resin (solids), and [E] 6,110 parts by mass of a mixed solvent of (E-1) / (E-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0251] [Examples 67-82 and Comparative Examples 11-20] Radiation-sensitive resin compositions (J-67) to (J-82) and (CJ-11) to (CJ-20) were prepared in the same manner as in Example 66, except that the components used were of the types and in the amounts shown in Table 6 below.

[0252] [Table 6]

[0253] [Viscosity measurement] The viscosity (mPa·s) of the radiation-sensitive resin composition was measured at 25 °C using a Canon Fenske viscometer.

[0254] [Formation of a resist pattern using a positive-type radiation-sensitive resin composition for EUV exposure] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming an anti-reflection film for the lower layer ("ARC66" from Brewer Science) was applied, and then heated at 205 °C for 60 seconds to form an anti-reflection film for the lower layer with an average thickness of 105 nm. On this anti-reflection film for the lower layer, the prepared radiation-sensitive resin composition for EUV exposure was applied using the above spin coater, and PB was performed at 130 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 55 nm was formed. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" from ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (32 nm line and space pattern).

[0255] [Evaluation] Regarding the resist pattern formed using the above positive-type radiation-sensitive resin composition for EUV exposure, the sensitivity, LWR performance, and pattern rectangularity were evaluated according to the following methods. The results are shown in Table 7 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" from Hitachi High-Technologies Corporation) was used.

[0256] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure, the exposure amount for forming a 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 30 mJ / cm². 2 The following cases are considered "good" and 30 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0257] [LWR performance] The mask size was adjusted to form a 32nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation described above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line jaggedness and better performance. LWR performance was evaluated as "good" if it was 3.0nm or less, and "poor" if it was greater than 3.0nm.

[0258] [Pattern Rectangle] The 32nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was "B" (good); and if it was greater than 1.10, it was "C" (poor).

[0259] [Table 7]

[0260] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example showed good sensitivity, LWR performance, and pattern rectangularity when used in EUV exposure, whereas the comparative example exhibited inferior characteristics compared to the example.

[0261] [Preparation of negative-type radiation-sensitive resin composition for ArF exposure, formation and evaluation of resist patterns using this composition] [Example 83] A radiation-sensitive resin composition (J-83) was prepared by mixing [A] 100 parts by mass of (A-5) as a resin, [B] 6.0 parts by mass of (B-1) as a first onium salt compound, [C] 6.0 parts by mass of (C-7) as a second onium salt compound, [D] 6.0 parts by mass of (D-1) as an acid diffusion control agent, [F] 3.0 parts by mass of (F-4) as a high fluorine-content resin (solids), and [E] 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0262] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure negative-type radiation-sensitive resin composition (J-83) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Annular (σ=0.8 / 0.6) through a mask pattern with 40 nm holes and a 105 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0263] The resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for ArF exposure were evaluated in the same manner as the resist patterns using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 83 showed good sensitivity, CDU performance, and pattern circularity even when a negative-type resist pattern was formed by ArF exposure.

[0264] [Preparation of negative-type radiation-sensitive resin composition for EUV exposure, formation and evaluation of resist patterns using this composition] [Example 84] A radiation-sensitive resin composition (J-84) was prepared by mixing [A] 100 parts by mass of (A-15) as a resin, [B] 9.0 parts by mass of (B-1) as a first onium salt compound, [C] 9.0 parts by mass of (C-11) as a second onium salt compound, [D] 3.0 parts by mass of (D-5) as an acid diffusion control agent, [F] 3.0 parts by mass of (F-5) as a high fluorine-content resin (solids), and [E] 6,110 parts by mass of a mixed solvent of (E-1) / (E-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0265] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. On this base layer anti-reflective coating, the prepared EUV exposure negative-type radiation-sensitive resin composition (J-84) was applied using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR15. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0266] The resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for EUV exposure were evaluated in the same manner as the resist patterns using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 84 showed good sensitivity, LWR performance, and pattern rectangularity even when a negative-type resist pattern was formed by EUV exposure. [Industrial applicability]

[0267] The radiation-sensitive resin composition and resist pattern formation method described above allow for the formation of resist patterns that exhibit good sensitivity to exposure light and have excellent CDU performance, pattern circularity, LWR performance, and pattern rectangularity. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. The first onium salt compound represented by the following formula (1), The second onium salt compound represented by the following formula (2), A resin containing structural units having acid-dissociable groups, Solvent and A radiation-sensitive resin composition containing [a specific substance]. 【Chemistry 1】 (In formula (1), R １ It is a monovalent, chain-like organic group having 1 to 40 carbon atoms. R ２ and R ３ Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. ２ and R ３ If multiple R ２ and R ３ They are either the same or different. R ｆ１１ and R ｆ１２ is each independently a fluorine atom or a monovalent fluorinated hydrocarbon group. R ｆ１１ and R ｆ１２ When there are a plurality of R ｆ１１ and R ｆ１２ are each the same or different. I understand １ and m ２ Each of these is an independent integer between 1 and 4. R ４ , R ５ , R ６ and R ７ Each of these is independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４ , R ５ , R ６ and R ７ If there are multiple instances of R, then there are multiple instances of R ４ , R ５ , R ６ and R ７ They are either the same or different. R ８ If there is one, R ８ R is a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ８ If multiple instances exist, R ８ Each of these is independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or multiple R ８ Two of these can be combined with each other to form a cyclic structure with 5 to 20 members, which is formed together with the two carbon atoms of the benzene ring in formula (1) above. n １ and n ２ Each of these is an independent integer between 1 and 4. n ３ (This is an integer between 1 and 5.) 【Chemistry 2】 (In formula (2), R Ｂ It is a monovalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. R ｆ２１ and R ｆ２２ Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group. ｆ２１ and R ｆ２２ If multiple R ｆ２１ and R ｆ２２ They are either the same or different. p is an integer between 1 and 4. Z ＋ (This is a monovalent, radiation-sensitive onium cation.)

2. In the above formula (1), R ２ , R ３ , R ｆ１１ and R ｆ１２ The radiation-sensitive resin composition according to claim 1, wherein the total number of fluorine atoms in is 3 or more.

3. In the above formula (1), R １ The radiation-sensitive resin composition according to claim 1, wherein the monovalent chain-like organic group having 1 to 40 carbon atoms represented by is a linear organic group having 1 to 40 carbon atoms.

4. In the above formula (1), R １ The radiation-sensitive resin composition according to claim 1, wherein the monovalent chain-like organic group having 1 to 40 carbon atoms represented by is a chain-like hydrocarbon group having 1 to 40 carbon atoms, a group in which at least one of an ether bond and a carbonyl group is incorporated in the chain or at the end of the chain of a chain-like hydrocarbon group having 1 to 40 carbon atoms, or a group in which some or all of the hydrogen atoms of a fluorinated chain-like hydrocarbon group having 1 to 40 carbon atoms are replaced with fluorine atoms.

5. In the above formula (1), m １ and m ２ The radiation-sensitive resin composition according to claim 1, wherein each of the elements is independently 1 or 2.

6. In the above formula (1), R ８ The radiation-sensitive resin composition according to claim 1, wherein is a chain-like hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 6 to 12 carbon atoms, a fluorine atom, or a fluorinated hydrocarbon group having 1 to 10 carbon atoms.

7. In the above formula (2), R Ｂ The radiation-sensitive resin composition according to claim 1, wherein the cyclic structure contained therein is an alicyclic polycyclic structure having 6 to 14 carbon atoms.

8. The radiation-sensitive resin composition according to claim 1, wherein the monovalent radiation-sensitive onium cation in formula (2) is a sulfonium cation or an iodonium cation.

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

10. The radiation-sensitive resin composition according to claim 1, wherein the mass-based ratio b / a of the content b of the second onium salt compound to the content a of the first onium salt compound is 0.05 or more and 20 or less.

11. The above-mentioned structural unit having an acid-dissociable group is represented by the following formula (3) in the radiation-sensitive resin composition according to claim 1. 【Transformation 3】 (In the formula, R １７ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R １８ It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R １９ and R ２０ Each of these independently comprises 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 １９ and R ２０ These are divalent alicyclic groups with 3 to 20 carbon atoms, formed by combining them with the carbon atoms to which they are bonded.

12. The radiation-sensitive resin composition according to claim 1, further comprising an acid diffusion control agent.

13. The radiation-sensitive resin composition according to claim 1, wherein the viscosity is 1.0 mPa·s or more and 15 mPa·s or less.

14. A step of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 13 onto a substrate, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. A pattern formation method including the following.

15. The pattern formation method according to claim 14, wherein the above exposure is performed by an ArF excimer laser.

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