Ionic salt and radiation-sensitive resist composition

Abstract

To provide means excellent in radiation (particularly EUV) absorption properties and enabling improvement of properties, such as sensitivity, developability and resolution.SOLUTION: Ionic salt is provided, consisting of a multivalent ion (a) having metal cluster structure or metal oxide cluster structure and an organic ion (b). The multivalent ion (a) includes at least one kind of metal atoms selected from a group consisting of tin, indium, antimony, tellurium and bismuth, and the organic ion (b) is at least one kind selected from a group consisting of: carboxylic acid anion having carbon numbers of 4 or more; sulfonic acid anion having carbon numbers of 4 or more; phosphonic acid anion having carbon numbers of 4 or more; phenoxide anion having carbon numbers of 6 or more; iodonium cation having carbon numbers of 4 or more; sulfonium cation having carbon numbers of 4 or more; ammonium cation having carbon numbers of 4 or more; and pyridinium cation having carbon numbers of 5 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ionic salt and a radiation-sensitive resist composition. [Background technology]

[0002] There is a constant demand for miniaturization of semiconductor processing, which will lead to faster semiconductor chips and lower power consumption, and research and development of lithography technology, which is at the core of this, is progressing. In recent years, extreme ultraviolet (EUV) has replaced lithography light sources, making it possible to obtain resist patterns with line widths of 20 nm or less. The chemically amplified resist used to obtain these resist patterns has superior sensitivity and resolution compared to materials used previously, and has been widely used since the days of the previous generation light source, the excimer laser.

[0003] However, chemically amplified resists lack both sensitivity and resolution to achieve the resist patterns with line widths of 10 nm or less that will be required in the future. One reason for this is that the organic materials contained in chemically amplified resists have low EUV absorption rates, making it difficult to efficiently convert the energy of photons emitted by EUV into chemical reactions. In response to this, metal-based resist materials have been proposed as new materials (see Patent Document 1). Metal atoms have a significantly higher EUV absorption coefficient than carbon and oxygen atoms, the main components of organic materials, and thus have the advantage of being able to capture photon energy. Therefore, compared to chemically amplified resists, metal-based resists have the advantage of superior sensitivity and resolution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-17780 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the technology described in Patent Document 1, sensitivity and resolution are insufficient, and further improvements in these properties have been desired.

[0006] Therefore, an object of the present invention is to provide a means for improving properties such as sensitivity, developability, and resolution while having excellent radiation (especially EUV) absorption properties. [Means for solving the problem]

[0007] The above-mentioned problems of the present invention can be solved by the following means: That is, one embodiment of the present invention is an ionic salt comprising (a) a multivalent ion having a metal cluster structure or a metal oxide cluster structure and (b) an organic ion, the polyvalent ion (a) contains at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth; The organic ion (b) is an ionic salt that is at least one selected from the group consisting of carboxylate anions having 4 or more carbon atoms; sulfonate anions having 4 or more carbon atoms; phosphonate anions having 4 or more carbon atoms; phenoxide anions having 6 or more carbon atoms; iodonium cations having 4 or more carbon atoms; sulfonium cations having 4 or more carbon atoms; ammonium cations having 4 or more carbon atoms; and pyridinium cations having 5 or more carbon atoms.

[0008] Another embodiment of the present invention is a radiation-sensitive resist composition comprising the above ionic salt and an organic solvent. [Effects of the Invention]

[0009] According to the present invention, a means is provided that has excellent radiation (especially EUV) absorption characteristics and can improve sensitivity and resolution. [Brief explanation of the drawings]

[0010] [Figure 1-1] FIG. 1 is a diagram showing the powder X-ray diffraction pattern of Compound 1 obtained in Synthesis Example 1. [Figure 1-2]FIG. 1 is a diagram showing the FT-IR spectrum of Compound 1 obtained in Synthesis Example 1. [Figure 2-1] FIG. 1 is a diagram showing the powder X-ray diffraction pattern of Compound 2 obtained in Synthesis Example 2. [Figure 2-2] FIG. 1 is a diagram showing the FT-IR spectrum of Compound 2 obtained in Synthesis Example 2. [Figure 3] FIG. 1 shows the FT-IR spectrum of Compound 3 obtained in Synthesis Example 3. [Figure 4] FIG. 1 shows the FT-IR spectrum of Compound 4 obtained in Synthesis Example 4. [Figure 5] FIG. 1 shows the FT-IR spectrum of Compound 5 obtained in Synthesis Example 5. [Figure 6] FIG. 1 shows the FT-IR spectrum of Compound 6 obtained in Synthesis Example 6. [Figure 7] FIG. 1 shows the FT-IR spectrum of Compound 7 obtained in Synthesis Example 7. [Figure 8] FIG. 1 shows the FT-IR spectrum of Compound 8 obtained in Synthesis Example 8. [Figure 9] FIG. 1 shows the FT-IR spectrum of Compound 9 obtained in Synthesis Example 9. [Figure 10] FIG. 1 shows the FT-IR spectrum of Compound 10 obtained in Synthesis Example 10. [Figure 11] FIG. 1 shows the FT-IR spectrum of Compound 11 obtained in Synthesis Example 11. [Figure 12] FIG. 1 shows the FT-IR spectrum of Compound 12 obtained in Synthesis Example 12. [Figure 13] FIG. 1 shows the FT-IR spectrum of Compound 13 obtained in Synthesis Example 13. [Figure 14] FIG. 1 shows the FT-IR spectrum of Compound 14 obtained in Synthesis Example 14. [Figure 15] FIG. 1 shows the FT-IR spectrum of Compound 15 obtained in Synthesis Example 15. [Figure 16] FIG. 1 shows the FT-IR spectrum of Compound 16 obtained in Synthesis Example 16. [Figure 17]FIG. 1 shows the FT-IR spectrum of Compound 17 obtained in Synthesis Example 17. [Figure 18] FIG. 1 shows the FT-IR spectrum of Compound 18 obtained in Synthesis Example 18. [Figure 19] FIG. 1 shows the FT-IR spectrum of Compound 19 obtained in Synthesis Example 19. [Figure 20] FIG. 1 shows the FT-IR spectrum of Compound 20 obtained in Synthesis Example 20. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. Furthermore, unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20°C to 25°C) and a relative humidity of 40% RH to 50% RH.

[0012] <Ionic salts> One aspect of the present invention is an ionic salt comprising a polyvalent ion (a) having a metal cluster structure or a metal oxide cluster structure and an organic ion (b), wherein the polyvalent ion (a) and the organic ion (b) are bonded to each other via an ionic bond to form the salt.

[0013] The polyvalent ion (a) contains at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth. The organic ion (b) is at least one selected from the group consisting of carboxylate anions having 4 or more carbon atoms, sulfonate anions having 4 or more carbon atoms, phosphonate anions having 4 or more carbon atoms, phenoxide anions having 6 or more carbon atoms, iodonium cations having 4 or more carbon atoms, sulfonium cations having 4 or more carbon atoms, ammonium cations having 4 or more carbon atoms, and pyridinium cations having 5 or more carbon atoms.

[0014] The ionic salt according to the present invention having the above-mentioned structure has excellent radiation (particularly EUV) absorption properties, and can improve properties such as sensitivity, developability, and resolution.

[0015] The present inventors presume that the mechanism by which the ionic salt having the above-described structure solves the problem is as follows.

[0016] The multivalent ion (a) according to the present invention contains at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth. These metal atoms have a high absorption coefficient for radiation (especially EUV), and can efficiently generate secondary electrons, thereby improving the sensitivity of the ionic salt according to the present invention.

[0017] Furthermore, the multivalent ionic nature of the multivalent ion (a) enables a wide range of structural designs for the counter ion organic ion (b), facilitating improvements in sensitivity, developability, resolution, and the like. Furthermore, the multivalent ionic nature increases the repulsive force between the multivalent ions (a), improving dispersibility in a liquid. Therefore, when a resist film is formed by applying a resist composition containing the ionic salt of the present invention, the uniformity of the resist film is improved, and the developability and resolution are likely to be improved.

[0018] Furthermore, the organic ion (b) according to the present invention has a structure in which secondary electrons generated from the multivalent ion (a) irradiated with radiation efficiently cause chemical reactions such as polarity change reactions and crosslinking reactions. The ionic salt of the present invention having such an organic ion (b) exhibits improved sensitivity, developability, resolution, etc.

[0019] The above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention. Similarly, the correctness of other speculations in this specification does not affect the technical scope of the present invention.

[0020] The ionic salt of the present invention will now be described.

[0021] [Ionic salts] <Multiply charged ions (a)> The ionic salt of the present invention has a multivalent ion (a) including a metal cluster or a metal oxide cluster. Here, "metal cluster" refers to an aggregate of compounds containing metal atoms that have a fixed structural unit formed by bonding between the metal atoms. Furthermore, "metal oxide cluster" refers to an atomic or molecular group or aggregate formed by bonding multiple types of atoms or molecules that constitute a metal oxide. By having such a cluster structure, the size of the multivalent ion (a) becomes smaller, and when used in a resist, resolution is improved.

[0022] The multivalent ion (a) according to the present invention contains at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth. From the viewpoint of further improving the absorption characteristics of radiation (especially EUV), the multivalent ion (a) preferably contains at least one metal atom selected from the group consisting of indium, antimony, tellurium, and bismuth.

[0023] The total number of metal atoms in the polyvalent ions (a) is preferably 4 to 30, and more preferably 4 to 20. Within this range, the size of the polyvalent ions (a) becomes smaller, and the resolution is further improved.

[0024] The content of at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth is preferably 50 at% or more relative to 100 at% of the total number of metal atoms in the multivalent ions (a). Such a content results in the presence of many metal atoms with a high absorption coefficient for radiation (especially extreme ultraviolet (EUV)), further improving sensitivity. The content of at least one metal atom selected from the group consisting of tin, indium, antimony, tellurium, and bismuth is more preferably 70 at% or more relative to 100 at% of the total number of metal atoms in the multivalent ions (a). The upper limit of this content is 100 at%.

[0025] The molecular weight of the polyvalent ion (a) is preferably 600 or more and 9000 or less, and more preferably 1000 or more and 6000 or less. If the molecular weight is within such a range, the size of the polyvalent ion (a) becomes smaller, and the resolution is further improved. In this specification, the molecular weight is the sum of the atomic weights of the atoms constituting the ion or compound.

[0026] The valence of the polyvalent ion (a) is preferably 3 or more, and more preferably 3 to 10. Such a valence can further improve the film uniformity of the resist film, and can further improve the sensitivity, developability, resolution, etc.

[0027] The average diameter of the polyvalent ions (a) is preferably 10 nm or less, more preferably 3 nm or less, from the viewpoint of further improving resolution. The lower limit of the average diameter is usually 0.5 nm or more. This average diameter can be measured by methods such as single crystal X-ray structural analysis and dynamic light scattering analysis of a solution.

[0028] The multivalent ion (a) according to the present invention may be anionic or cationic. Furthermore, the multivalent ion (a) according to the present invention may be one type alone or a combination of two or more types.

[0029] Specific examples of the multivalent ion (a) according to the present invention are shown below.

[0030] [ka]

[0031] Among these polyvalent ions (a), one or more of the ions listed below are preferred.

[0032] [ka]

[0033] (Method for preparing multivalent ions (a)) Commercially available metal-containing compounds can be used as the metal-containing component of the metal cluster or metal oxide cluster contained in the polyvalent ion (a). For example, a metal cluster or metal oxide cluster can be synthesized by carrying out a hydrolysis condensation reaction using this metal-containing compound. Here, the term "hydrolysis condensation reaction" refers to a reaction in which a hydrolyzable group in a metal compound is hydrolyzed to -OH, and the resulting two -OH groups undergo dehydration condensation to form -O-.

[0034] Examples of the metal-containing compound include a metal compound having a hydrolyzable group, a hydrolyzate of the metal compound (I) having a hydrolyzable group, a hydrolysis condensate of a metal compound having a hydrolyzable group, or a combination thereof. The metal-containing compound may be used alone or in combination of two or more.

[0035] More specific methods for the hydrolysis and condensation reaction include, for example, the sol-gel method, hydrothermal synthesis, glycothermal method, as well as ordinary sintering, synthesis in a gas flow, etc. Furthermore, the method may include a property adjustment step in which the desired range of properties is obtained by hydrothermal treatment subsequent to the hydrolysis and condensation reaction.

[0036] Representative structures of metal oxide clusters include the Keggin structure, the Wells-Dawson structure, the Anderson-Evans-Perloff structure, etc. However, the structure of the metal oxide cluster according to the present invention is not necessarily limited to these.

[0037] <Organic ions (b)> The organic ion (b) according to the present invention has a structure in which secondary electrons generated from the multivalent ion (a) irradiated with radiation efficiently cause chemical reactions such as polarity change reactions and crosslinking reactions. The ionic salt of the present invention containing such an organic ion (b) exhibits improved developability, resolution, etc.

[0038] The organic ion (b) is at least one selected from the group consisting of a carboxylate anion having 4 or more carbon atoms; a sulfonate anion having 4 or more carbon atoms; a phosphonate anion having 4 or more carbon atoms; a phenoxide anion having 6 or more carbon atoms; an iodonium cation having 4 or more carbon atoms; a sulfonium cation having 4 or more carbon atoms; an ammonium cation having 4 carbon atoms; and a pyridinium cation having 5 or more carbon atoms.

[0039] The number of carbon atoms in the carboxylate anion, sulfonate anion, phosphonate anion, iodonium cation, sulfonium cation, and ammonium cation is 4 or more. If the number of carbon atoms in these ions is less than 4, the solvent solubility and photosensitivity decrease, resulting in poor resolution and sensitivity as a resist. The number of carbon atoms is preferably 6 or more, and more preferably 8 or more.

[0040] The phenoxide anion has 6 or more carbon atoms, preferably 8 or more carbon atoms, and more preferably 10 or more carbon atoms.

[0041] The pyridinium cation has 5 or more carbon atoms, preferably 7 or more carbon atoms, and more preferably 9 or more carbon atoms.

[0042] The upper limit of the number of carbon atoms in these ions is not particularly limited, but is usually 100 or less, and preferably 30 or less.

[0043] When the organic ion (b) is an ammonium cation or a pyridinium cation, these ions preferably have at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group.

[0044] The term "carbon-carbon multiple bond-containing group" refers to a group containing a double or triple bond between two carbon atoms. The double bond includes conjugated double bonds in an aromatic hydrocarbon ring or an aromatic heterocycle.

[0045] Examples of the carbon-carbon double bond-containing group include ethylenic double bond-containing groups such as a vinyl group, a vinyloxy group, an allyl group, an allyloxy group, a (meth)acryloyl group, a (meth)acryloyloxy group, and a maleimide group; aromatic carbon ring-containing groups such as a phenyl group, a naphthyl group, an anthracene group, a benzoic acid group, a cinnamic acid group, an anthraquinone group, a styryl group, a stilbene group, a styrylpyridine group, and a ketoprofen group; aromatic heterocycle-containing groups such as a nicotinic acid group and a thioxanthone group; and groups in which some or all of the hydrogen atoms of these groups have been substituted with a hydroxy group, a halogen atom, a monovalent organic group, or the like (hereinafter, these may be referred to as "substituents (a)").

[0046] Examples of the carbon-carbon triple bond-containing group include a propargyl group, a propargyloxy group, groups in which some or all of the hydrogen atoms of these groups have been substituted with substituent (a), an ethynyl group, an ethynyloxy group, an ethynylcarbonyl group-containing group, and a phenylethynylcarbonyl group-containing group.

[0047] The carbonyl group-containing group is a group containing a carbonyl group (>C=O), and examples thereof include an aldehyde group, a ketone group, a carboxy group, an alkoxycarbonyl group (ester group), an amide group, an isocyanate group, a carbamate group (-OC(O)NH), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), a carbonate group (-OC(O)O-), etc. More specific examples include an acetophenone group, a benzophenone group, a ketoprofen group, etc.

[0048] Examples of the oxime ester group include oxime methyl ester and oxime ethyl ester.

[0049] Examples of halogenated alkyl groups include groups in which at least one hydrogen atom in a linear, branched, or cyclic alkyl group having from 1 to 10 carbon atoms has been substituted with a halogen atom. Examples of halogen atoms in the halogenated alkyl group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0050] The phosphorus-containing group is a group containing at least one phosphorus atom, and examples thereof include a phosphonic acid group, a phosphinic acid group, a phosphine oxide group, a phosphonous acid group, a phosphinous acid group, and a phosphine group.

[0051] Examples of the diazo group include a diazoalkane group, a diazonaphthoquinone group, and a diaziridine group.

[0052] Examples of the azido group include an azidomethyl group, an azidoethyl group, an azidoaryl group, and the like.

[0053] The ammonium cation and pyridinium cation according to the present invention preferably have the above-mentioned functional group, and the other organic ion (b) also preferably has the above-mentioned functional group. That is, according to a preferred embodiment of the present invention, the organic ion (b) has at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group.

[0054] According to a more preferred embodiment, the organic ion (b) has at least one functional group selected from the group consisting of a vinyl group, a stilbene group, an azide group, a diazoalkane group, a diaziridine group, a cinnamic acid group, an anthracene group, an anthraquinone group, a maleimide group, a styrylpyridine group, an arylsulfonium group, an aryliodonium group, and a phenyl ester group.

[0055] The organic ion (b) according to the present invention may be a monovalent ion or a polyvalent ion (divalent or higher), but is preferably monovalent from the viewpoint of resolution. The organic ion (b) according to the present invention may be anionic or cationic. Furthermore, the organic ion (b) constituting the ionic salt of the present invention may be a single type or a combination of two or more types.

[0056] Specific examples of the organic ion (b) according to the present invention are given below.

[0057] [ka]

[0058] From the viewpoint of making the size of the ionic salt smaller and further improving the resolution, the molecular weight of the organic ion (b) is preferably 50 or more and 5,000 or less, and more preferably 100 or more and 1,000 or less.

[0059] <Specific examples of ionic salts> Specific examples of the ionic salt of the present invention include the following compounds.

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [Method for producing ionic salts] The method for producing the ionic salt of the present invention is not particularly limited, and examples thereof include a method in which a compound having a polyvalent ion (a) including a metal cluster or a metal oxide cluster is mixed with a compound having an organic ion (b) to carry out a salt exchange reaction. The salt exchange reaction can be easily carried out by a known method, and if necessary, the resulting product can be purified by a conventional method such as filtration, distillation, extraction, washing with water or an organic solvent, crystallization, treatment with an acid, treatment with an alkali, or column chromatography. These purification methods are preferably repeated to adjust the impurity concentration of the composition to the desired range.

[0071] The compound having the polyvalent ion (a) and the compound having the organic ion (b) may be commercially available or synthesized. The synthesis method of these compounds can be appropriately selected by referring to conventionally known methods.

[0072] If necessary, the compound having the polyvalent ion (a) and the compound having the organic ion (b) can be purified by the following means. Purification means include filtration, distillation, extraction, washing with water or an organic solvent, recrystallization, crystallization, treatment with an acid, treatment with an alkali, and purification by column chromatography, and can be appropriately selected from these depending on the properties of the impurities to be removed. Among these, purification by filtration, column chromatography, recrystallization, or crystallization is preferred, and purification by recrystallization is more preferred. These purification means are preferably repeated to adjust the impurity concentration of the composition to a desired range.

[0073] The structure (composition) of the ionic salt of the present invention can be confirmed by FT-IR analysis, NMR analysis, X-ray fluorescence (XRF) analysis, mass spectrometry, UV analysis, single crystal X-ray structural analysis, powder X-ray diffraction (PXRD) analysis, liquid chromatography (LC) analysis, size exclusion chromatography (SEC) analysis, thermal analysis, etc. Detailed confirmation methods are as described in the Examples.

[0074] The ionic salt of the present invention preferably has a total molecular weight of 650 or more and 30,000 or less, more preferably 900 or more and 15,000 or less, from the viewpoint of improving resolution.

[0075] Furthermore, from the viewpoint of radiation absorption and photosensitivity, the ionic salt of the present invention preferably has a ratio of the molecular weight of the polyvalent ion (a) to the total molecular weight of the organic ions (b) [molecular weight of (a) / total molecular weight of (b)] of 0.3 to 30, and more preferably 0.5 to 10.

[0076] The total molecular weight of organic ions (b) refers to the total molecular weight of all organic ions (b) contained in an ionic salt. For example, five monovalent organic ions (b) are bonded to a pentavalent inorganic ion (a), and the total molecular weight of the five ions is the total molecular weight of the organic ions (b).

[0077] According to a preferred embodiment of the present invention, the ionic salt is preferably such that the multivalent ion (a) is cationic and the organic ion (b) is anionic.

[0078] [Radiation-sensitive resist composition] According to another embodiment of the present invention, there is provided a radiation-sensitive resist composition comprising the ionic salt of the present invention and an organic solvent. The radiation-sensitive resist composition comprising the ionic salt of the present invention has excellent radiation (especially EUV) absorption characteristics, and is also excellent in properties such as sensitivity, developability, and resolution.

[0079] The radiation-sensitive resist composition of this embodiment changes in solubility in a developer upon exposure to radiation. The radiation-sensitive resist composition of this embodiment may be a positive resist composition in which an exposed portion of a resist film is dissolved and removed to form a positive resist pattern, or a negative resist composition in which an unexposed portion of a resist film is dissolved and removed to form a negative resist pattern. Furthermore, the radiation-sensitive resist composition of this embodiment may be for use in an alkaline development process in which an alkaline developer is used in the development treatment during resist pattern formation, or may be for use in a solvent development process in which a developer containing an organic solvent (hereinafter also referred to as an organic developer) is used in the development treatment.

[0080] The ionic salt of the present invention has been described above, and the organic solvent and optional components contained as necessary will be described below. The ionic salt of the present invention contained in the radiation-sensitive resist composition may be used alone or in combination of two or more.

[0081] <Organic solvents> The organic solvent contained in the radiation-sensitive resist composition of the present invention is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the ionic salt of the present invention and any optional components contained as desired. The organic solvent may be the same as that used in synthesizing the ionic salt. The organic solvent may be used alone or in combination of two or more. A mixed solvent of water and an organic solvent may also be used.

[0082] Examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, sulfoxide solvents, and hydrocarbon solvents.

[0083] More specifically, examples of alcohol-based solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, and trimethylolpropanol. monoalcohol solvents such as methylcyclohexanol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol; polyalcohol solvents such as ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol;Examples of the polyhydric alcohol partial ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monopropyl ether;

[0084] Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0085] Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, diisobutyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0086] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methyl-2-pyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0087] Examples of ester solvents include acetate ester solvents such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, n-pentyl acetate, isopentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, and n-nonyl acetate; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. Examples of suitable solvents include polyhydric alcohol partial ether carboxylate solvents such as γ-butyrolactone and δ-valerolactone; lactone solvents such as γ-butyrolactone and δ-valerolactone; carbonate solvents such as dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate; lactate ester solvents such as methyl lactate, ethyl lactate, n-butyl lactate, and n-amyl lactate; glycol diacetate, methoxytriglyceride acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetoacetate, diethyl malonate, dimethyl phthalate, and diethyl phthalate.

[0088] Examples of sulfoxide solvents include dimethyl sulfoxide and diethyl sulfoxide.

[0089] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, 2,2,4-trimethylpentane, n-octane, isooctane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, isopropylbenzene, diethylbenzene, isobutylbenzene, triethylbenzene, diisopropylbenzene, and n-amylnaphthalene.

[0090] Among these organic solvents, alcohol solvents, amide solvents, ester solvents, and sulfoxide solvents are preferred, and propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, ethyl lactate, and dimethyl sulfoxide are even more preferred.

[0091] <Optional ingredients> The radiation-sensitive resist composition according to the present invention may contain, in addition to the ionic salt and organic solvent, optional components such as a radiation-sensitive acid generator, a fluorine atom-containing polymer, a surfactant, a crosslinking agent, a leveling agent, a colorant, or a combination thereof.

[0092] The surfactant has the effect of improving coatability, striation, developability, etc. Specific examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate. Commercially available surfactants or synthetic surfactants may be used. Examples of commercially available surfactants include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, No. 95 (all manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac (registered trademark) F171, F173, R40, R41, R43 (all manufactured by DIC Corporation), Fluorad (registered trademark) FC430, FC431 (all manufactured by 3M), Asahiguard AG710 (manufactured by AGC Corporation), Surflon (registered trademark) S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by AGC Seimi Chemical Co., Ltd.), and the like.

[0093] Examples of the crosslinking agent include, but are not limited to, a melamine-based crosslinking agent, a substituted urea-based crosslinking agent, or a polymer-based crosslinking agent. Examples of the crosslinking agent having at least two crosslink-forming substituents that can be used include compounds such as methoxymethylated glycoluril, butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, and methoxymethylated thiourea.

[0094] The leveling agent is used to improve the flatness of the coating film during printing (application), and any known leveling agent that is commercially available can be used.

[0095] The radiation-sensitive resist composition of the present invention may contain a silane coupling agent as an optional component in order to improve adhesion to the substrate, etc. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane; silane compounds containing a carbon-carbon unsaturated bond, such as 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane; trimethoxy[3-(phenylamino)propyl]silane, etc.

[0096] The amount of these optional components used can be easily adjusted and appropriately set depending on the desired physical properties. These optional components can be used either alone or in combination of two or more.

[0097] The method for producing the radiation-sensitive resist composition of the present invention is not particularly limited, and examples thereof include a method in which an ionic salt and optional components added as needed are mixed in an organic solvent. The temperature and time during mixing are not particularly limited. If necessary, filtration may be performed after mixing.

[0098] The content of the ionic salt in the radiation-sensitive resist composition of the present invention (the total amount when two or more types are used) is preferably 0.5% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 20% by mass or less, based on 100% by mass of the total mass of the composition.

[0099] <Pattern formation method> The pattern formation method using the radiation-sensitive resist composition of the present invention is not particularly limited. However, according to a preferred embodiment, the method comprises the steps of applying the radiation-sensitive resist composition of the present invention to a substrate to form a resist film (hereinafter also referred to as the "coating step"), exposing the resist film formed by the coating step (hereinafter also referred to as the "exposure step"), and developing the exposed resist film (hereinafter also referred to as the "developing step"). Because the pattern formation method uses the radiation-sensitive resist composition of the present invention, it is possible to form a pattern with high sensitivity, high developability, and high resolution. Each step will be described below.

[0100] [Coating process] In this process, a radiation-sensitive resist composition is applied to one side of a substrate, thereby forming a resist film. The application method is not particularly limited, and examples thereof include spin coating, spray coating, dip coating, knife-edge coating, inkjet printing, and screen printing. Examples of the substrate include silicon wafers and aluminum-coated wafers. Specifically, the radiation-sensitive resist composition is applied to the substrate so that the resulting film has a predetermined thickness, and then the substrate is prebaked (PB) as needed to volatilize the solvent in the coating film.

[0101] The lower limit of the thickness of the resist film after prebaking is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more, and the upper limit of the thickness of the resist film after prebaking is preferably 1,000 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less.

[0102] The lower limit of the pre-baking temperature is preferably 60°C or higher, more preferably 80°C or higher. The upper limit of the pre-baking temperature is preferably 150°C or lower, more preferably 140°C or lower. The lower limit of the pre-baking time is preferably 5 seconds or higher, more preferably 10 seconds or higher. The upper limit of the pre-baking time is preferably 600 seconds or lower, more preferably 300 seconds or lower.

[0103] [Exposure process] In this step, the film formed in the coating step is exposed to light. This exposure is sometimes carried out by irradiating the film with radiation through an immersion medium such as water and a mask having a desired pattern. Examples of the radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV, wavelength 13.5 nm), X-rays, and gamma rays; and charged particle beams such as electron beams (EB) and alpha rays. In this specification, irradiation with these types of radiation may be collectively referred to as "exposure."

[0104] Among these radiations, radiation that causes a large number of secondary electrons to be emitted from the metal atoms contained in the multivalent ions (a) upon exposure is preferred, and extreme ultraviolet (EUV) radiation or an electron beam is more preferred.

[0105] Various exposure light sources can be used, including those that emit ultraviolet laser light such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), and F2 excimer laser (wavelength 157 nm), those that convert the wavelength of laser light from a solid-state laser light source (such as a YAG or semiconductor laser) to emit harmonic laser light in the far ultraviolet or vacuum ultraviolet region, and those that irradiate with electron beams or extreme ultraviolet light (EUV). During exposure, exposure is usually carried out through a mask corresponding to the desired pattern, but when the exposure light source is an electron beam, exposure may be by direct writing without using a mask.

[0106] The cumulative dose of radiation in this process is, for example, 2000 mJ / cm when extreme ultraviolet radiation is used as the radiation. 2 Preferably, it is 500 mJ / cm or less. 2 When using an electron beam, the cumulative dose is preferably 5000 μC / cm 2 or less. 2 Preferably, it is 1000 μC / cm or less. 2 More preferably, it is:

[0107] After the exposure, post-exposure baking (PEB) may be performed. The lower limit of the PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. The upper limit of the PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The lower limit of the PEB time is preferably 5 seconds or higher, more preferably 10 seconds or higher. The upper limit of the PEB time is preferably 600 seconds or lower, more preferably 300 seconds or lower.

[0108] In the present invention, in order to maximize the capabilities of the radiation-sensitive resist composition, for example, an organic or inorganic anti-reflective film may be formed on the substrate to be used. Furthermore, in order to prevent the influence of basic impurities and the like contained in the ambient atmosphere, for example, a protective film may be provided on the coating film. Furthermore, when immersion exposure is performed, for example, an immersion protective film may be provided on the resist film to prevent direct contact between the immersion medium and the resist film.

[0109] [Development process] In this step, the resist film exposed in the exposure step is developed. Developers used in this development include alkaline developers and developers containing organic solvents (hereinafter also referred to as "organic developers"). Development methods include dipping, puddling, spraying, and dynamic dispensing. The development temperature is preferably, for example, 5°C or higher and 60°C or lower, and the development time is preferably, for example, 5 seconds or higher and 300 seconds or lower.

[0110] Examples of alkaline developers include alkaline aqueous solutions containing at least one alkaline compound dissolved therein, 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 (DBU), and 1,5-diazabicyclo-[4.3.0]-5-nonene (DBN). The alkaline developer may contain a surfactant.

[0111] The lower limit of the alkaline compound content in the alkaline developer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and the upper limit of the alkaline compound content is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0112] After development, the resist pattern is preferably washed with ultrapure water, and then water remaining on the substrate and pattern is removed.

[0113] Examples of the organic solvent contained in the organic developer include the same organic solvents as those exemplified in the section <Organic solvent> of the above [Radiation-sensitive resist composition].

[0114] The lower limit of the content of the organic solvent in the organic 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. The organic developer may contain a surfactant. The organic developer may also contain a trace amount of water. During development, development may be stopped by replacing the organic developer with a different type of solvent.

[0115] It is preferable to wash the resist pattern after development. Ultrapure water, a rinse solution, etc. can be used as the washing solution. There are no particular restrictions on the rinse solution as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent can be used. A preferred rinse solution is an alcohol-based solvent or an ester-based solvent. After washing, it is preferable to remove the rinse solution remaining on the substrate and pattern. Furthermore, when ultrapure water is used, it is preferable to remove the water remaining on the substrate and pattern.

[0116] These developers may be used singly or in combination of two or more.

[0117] After forming the resist pattern as described above, a patterned wiring substrate can be obtained by etching. The etching method can be a known method such as dry etching using plasma gas or wet etching using an alkaline solution, cupric chloride solution, ferric chloride solution, or the like.

[0118] After forming the resist pattern, plating can be carried out. The plating method is not particularly limited, but examples thereof include copper plating, solder plating, nickel plating, and gold plating.

[0119] The remaining resist pattern after etching can be stripped off with an organic solvent. Examples of such organic solvents include, but are not limited to, PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), and EL (ethyl lactate). Stripping methods include, but are not limited to, immersion methods, spraying methods, and the like. The wiring board on which the resist pattern is formed may be a multilayer wiring board and may have small-diameter through-holes.

[0120] In this embodiment, the wiring board can also be formed by a method in which a resist pattern is formed, a metal is evaporated in a vacuum, and then the resist pattern is dissolved in a solution, that is, by a lift-off method.

[0121] <Application> The radiation-sensitive resist composition of the present invention is suitable as a resist composition for KrF excimer laser exposure, ArF excimer laser exposure, electron beam exposure, or EUV exposure, and is more preferably a resist composition for electron beam exposure or EUV exposure, and can be suitably used in semiconductor microfabrication. [Example]

[0122] The present invention will be described in more detail using the following examples and comparative examples, but the technical scope of the present invention is not limited to the following examples. Various analyses were performed according to the following methods.

[0123] [Analysis method] (Powder X-ray diffraction measurement) The analysis was carried out using an X-ray diffractometer (Bruker, D8 advance, X-ray source: CuKα, output 40 kV-40 mA).

[0124] (Fourier transform infrared spectroscopy (FT-IR) measurement) Fourier transform infrared spectroscopy was measured by the ATR method using a Fourier transform infrared spectrophotometer (Nicolet iS10, manufactured by Thermo Scientific).

[0125] (Measurement of Bi element content (elemental analysis)) Using an energy dispersive X-ray analyzer (Horiba, Ltd., EMAXEvolution), the six elements Bi, C, N, S, F, and O in the compound were measured, and the content (mass%) of Bi element was calculated, with the total of the six elements being 100 mass%.

[0126] (Synthesis Example 1) <Compound 1 {[Bi6O5(OH)3(NO3)3]2} 4+ 4NO3 - Synthesis of> Compound 1 was synthesized according to the synthesis method described in Acta Cryst. (1978). B34, 3169-3173. Specifically, 10.000 g (20.51 mmol) of bismuth nitrate pentahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) and 14.950 g of 60% nitric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 2 L glass beaker, stirred, and then diluted with 990 mL of purified water. After stirring for 15 minutes, a 4% aqueous solution of sodium hydroxide was added to adjust the pH of the reaction solution to 1.5. During the dropwise addition of the aqueous sodium hydroxide solution, a white precipitate formed. The mixture was then stirred for 1 hour, and the precipitate was separated by vacuum filtration using a paper filter. The solid was washed with purified water and then dried under vacuum at 60 °C for 10 hours, yielding 5.785 g of compound 1 as a white powder.

[0127] Compound 1 was identified by powder X-ray diffraction. The crystal structure of compound 1 is registered as CCDC 1592300 in the Cambridge Structural Database (CSD, HP: https: / / www.ccdc.cam.ac.uk / ). The powder X-ray diffraction pattern of compound 2 obtained in this synthesis is shown in the lower part of Figure 1-1, and the powder X-ray diffraction pattern simulated using the reported crystal structure data is shown in the upper part of Figure 1-1. These two patterns were nearly identical, confirming that the obtained compound 1 is the compound registered as CCDC 1592300.

[0128] The FT-IR spectrum of the obtained compound 1 is shown in FIG. 1-2.

[0129] In Acta Cryst. (1978). B34, 3169-3173, Compound 1 is [Bi6O5(OH)3] + 5NO3 - However, in Inorg. Chem. 2012, 51, 9376-9384, it is written as a dimer structure {[Bi6O5(OH)3(NO3)3]2} 4+ 4NO3 - It has been pointed out that this is the case.

[0130] (Synthesis Example 2) <Compound 2 [Bi9O8(OH)6] 5+ 5CF3SO3 - Synthesis of> Compound 1 was synthesized according to the synthesis method described in Inorg. Chem. 2010, 49, 5619-5624. Specifically, 1.053 g (0.208 mmol) of bismuth(III) oxide (Fujifilm Wako Pure Chemical Industries, Ltd.), 0.680 g (0.417 mmol) of trifluoromethanesulfonic acid (Fujifilm Wako Pure Chemical Industries, Ltd.), and 16.3 ml of pure water were placed in a polytetrafluoroethylene PTFE beaker and stirred for 10 minutes using a magnetic stirrer. The pH of the solution was 0.9. Subsequently, 28-30% ammonia water (Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to adjust the pH of the solution to 3.1. The resulting solution was placed in a 25 ml high-pressure reactor (San-ai Science Co., Ltd.) and sealed. The sealed reaction vessel was placed in a thermostatic bath and heated at 175° C. for 48 hours, and then cooled to room temperature (25° C.) The precipitate in the reaction solution was separated by filtration to obtain 1.010 g of crystalline compound 2.

[0131] Compound 2 was identified by powder X-ray diffraction, as in the case of compound 1. The crystal structure of compound 2 is registered as CCDC 788955. The powder X-ray diffraction pattern of compound 2 obtained in this synthesis is shown in the lower part of Figure 2-1, and the powder X-ray diffraction pattern simulated using the reported crystal structure data is shown in the upper part of Figure 2-1. These two patterns were almost identical, confirming that the obtained compound 2 is the compound registered as CCDC 788955.

[0132] The FT-IR spectrum of the obtained compound 2 is shown in FIG. 2-2.

[0133] [Synthesis Example 3] <Compound 3 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4-propoxycinnamic acid anion <Synthesis of sodium 4-propoxycinnamate> 1.650 g (8 mmol) of 4-propoxycinnamic acid (Tokyo Chemical Industry Co., Ltd.) was placed in a 50 ml eggplant-shaped flask, and an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (Tokyo Chemical Industry Co., Ltd.) in 20 ml of pure water was added dropwise and stirred to obtain a colorless, transparent aqueous solution of sodium 4-propoxycinnamate. Water was removed using an evaporator and a vacuum dryer, yielding 1.825 g of sodium 4-propoxycinnamate.

[0134] ≪Compound 3 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (4-propoxycinnamic acid anion)≫ 0.700 g (0.2 mmol) of compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 1. A solution consisting of 0.456 g (2 mmol) of sodium 4-propoxycinnamate, 40,000 g of DMSO, and 40,000 g of pure water heated to 70°C was added dropwise with stirring and allowed to react at 25°C for 1 hour, resulting in a solution containing a white precipitate. The liquid and precipitate were separated using a centrifuge. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The water was then removed by vacuum drying, yielding 0.750 g of compound 3 as a white powder. FT-IR analysis (see Figure 3) confirmed that the nitrate ion, the anion moiety of compound 1, had been replaced with a 4-propoxycinnamate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 3 was obtained.

[0135] (Synthesis Example 4) <Compound 4 [Bi9O8(OH)6] 5+ Synthesis of 5 (4-propoxycinnamic acid anion) 0.559 g (0.2 mmol) of compound 2 obtained in Synthesis Example 2 above and 13.981 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 2. A solution consisting of 0.456 g (2 mmol) of sodium 4-propoxycinnamate, 40,000 g of DMSO, and 40,000 g of pure water, preheated to 70°C, was added dropwise with stirring and allowed to react at 25°C for 1 hour, resulting in a solution containing a white precipitate. The liquid and precipitate were separated using a centrifuge. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The water was then removed by vacuum drying, yielding 0.452 g of compound 4 as a white powder. FT-IR analysis (see Figure 4) confirmed that the trifluoromethanesulfonate ion, the anion moiety of compound 2, had been replaced with a 4-propoxycinnamate ion. Furthermore, the results of elemental analysis showed that the content (mass %) of Bi element was almost identical to the theoretical value, confirming that Compound 4 was obtained.

[0136] (Synthesis Example 5) <Compound 5 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (9,10-dimethoxyanthracene-2-sulfonic acid anion) 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.681 g (2 mmol) of 9,10-dimethoxyanthracene-2-sulfonic acid (Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 17.490 g of pure water was added dropwise, resulting in a solution containing an orange precipitate. The liquid and precipitate were separated using a centrifuge. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.710 g of Compound 5 as an orange powder. The FT-IR analysis results (see Figure 5) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with a 9,10-dimethoxyanthracene-2-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi (mass%) was almost identical to the theoretical value, confirming that Compound 5 was obtained.

[0137] (Synthesis Example 6) <Compound 6 [Bi9O8(OH)6] 5+ Synthesis of 5 (9,10-dimethoxyanthracene-2-sulfonic acid anion) 0.559 g (0.2 mmol) of Compound 2 obtained in Synthesis Example 2 above and 13.981 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 2. A solution consisting of 0.681 g (2 mmol) of 9,10-dimethoxyanthracene-2-sulfonic acid (Tokyo Chemical Industry Co., Ltd.), 13.981 g of DMSO, and 1.398 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 13.981 g of pure water was added dropwise, resulting in a solution containing an orange precipitate. The liquid and precipitate were separated using a centrifuge. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.663 g of Compound 6 as an orange powder. The FT-IR analysis results (see Figure 6) confirmed that the trifluoromethanesulfonate ion, which is the anion moiety of Compound 2, was replaced with a 9,10-dimethoxyanthracene-2-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi (mass%) was almost identical to the theoretical value, confirming that Compound 6 was obtained.

[0138] (Synthesis Example 7) <Compound 7 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (anthraquinone-2-sulfonic acid anion) 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.657 g (2 mmol) of sodium anthraquinone-2-sulfonate monohydrate (Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 8.745 g of pure water was added dropwise to obtain a solution containing a yellow precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.651 g of Compound 7 as a yellow powder. The FT-IR analysis results (see FIG. 7) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with an anthraquinone-2-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi element (mass%) was almost identical to the theoretical value, confirming that Compound 7 was obtained.

[0139] (Synthesis Example 8) <Compound 8 [Bi9O8(OH)6] 5+ Synthesis of 5 (anthraquinone-2-sulfonic acid anion) 0.559 g (0.2 mmol) of compound 2 obtained in Synthesis Example 2 above and 13.981 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 2. A solution consisting of 0.657 g (2 mmol) of sodium anthraquinone-2-sulfonate monohydrate (Tokyo Chemical Industry Co., Ltd.), 13.981 g of DMSO, and 1.398 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. 6.991 g of pure water was then added dropwise to obtain a solution containing a yellow precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.571 g of compound 8 as a yellow powder. The FT-IR analysis results (see FIG. 8) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with an anthraquinone-2-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi element (mass%) was almost consistent with the theoretical value, confirming that Compound 8 was obtained.

[0140] (Synthesis Example 9) <Compound 9 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (4-azidobenzoate anion) <Synthesis of sodium 4-azidobenzoate> A 50 ml eggplant-shaped flask was charged with 1.305 g (8 mmol) of 4-azidobenzoic acid (Tokyo Chemical Industry Co., Ltd.), and an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (Tokyo Chemical Industry Co., Ltd.) in 20 ml of purified water was added dropwise and stirred to obtain a brown, transparent aqueous solution of sodium 4-azidobenzoate. Water was removed using an evaporator and a vacuum dryer to obtain 1.620 g of sodium 4-azidobenzoate.

[0141] ≪Compound 9 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (4-azidobenzoic acid anion)≫ 0.700 g (0.2 mmol) of compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 1. A solution consisting of 0.370 g (2 mmol) of sodium 4-azidobenzoate, 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring and allowed to react at 25°C for 1 hour, resulting in a solution containing a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The water was then removed by vacuum drying, yielding 0.403 g of compound 13 as a white powder. FT-IR analysis (see Figure 9) confirmed that the nitrate ion, the anion moiety of compound 1, had been replaced with a 4-azidobenzoate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 9 was obtained.

[0142] (Synthesis Example 10) <Compound 10 [Bi9O8(OH)6] 5+ Synthesis of 5 (4-azidobenzoic acid anion) A solution of Compound 2 (0.559 g, 0.2 mmol) was prepared in Synthesis Example 2 and 13.981 g of dimethyl sulfoxide (DMSO) was stirred in a glass beaker to prepare a solution of Compound 2. A solution consisting of 0.370 g (2 mmol) of sodium 4-azidobenzoate, 13.981 g of DMSO, and 1.398 g of pure water was added dropwise to the solution while stirring, and the mixture was allowed to react at 25°C for 1 hour, resulting in a solution containing a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The water was then removed by vacuum drying, yielding 0.376 g of Compound 10 as a white powder. FT-IR analysis (see Figure 10) confirmed that the nitrate ion, the anion moiety of Compound 1, had been replaced with a 4-azidobenzoate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 10 was obtained.

[0143] (Synthesis Example 11) <Compound 11 [Bi9O8(OH)6] 5+ Synthesis of 5 (6-maleimidohexanoic acid anion) <Synthesis of sodium 6-maleimidohexanoate> A 50 ml eggplant-shaped flask was charged with 1.690 g (8 mmol) of 6-maleimidohexanoic acid (Tokyo Chemical Industry Co., Ltd.), and an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (Tokyo Chemical Industry Co., Ltd.) in 32 ml of purified water and 20.8 g of 2-propanol was added dropwise and stirred to obtain a colorless, transparent solution of sodium 6-maleimidohexanoate. Water and 2-propanol were removed using an evaporator and a vacuum dryer, yielding 1.820 g of sodium 6-maleimidohexanoate.

[0144] Synthesis of Compound 11 {[Bi6O5(OH)3(NO3)3]2}4+·4 (6-maleimidohexanoic acid anion) 0.700 g (0.2 mmol) of compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 1. A solution consisting of 0.456 g of sodium 6-maleimidohexanoate, 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 8.745 g of pure water was added dropwise to obtain a solution in which a white precipitate formed. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.383 g of compound 13 as a white powder. The FT-IR analysis results (see FIG. 11) confirmed that the anion moiety of Compound 1 had been substituted from nitrate ions to 6-maleimidohexanoic acid ions, and the elemental analysis results showed that the content of Bi (mass%) matched the calculated value, confirming that Compound 11 had been obtained.

[0145] (Synthesis Example 12) <Compound 12 [Bi9O8(OH)6] 5+Synthesis of 5 (6-maleimidohexanoic acid anion) 0.559 g (0.2 mmol) of compound 2 obtained in Synthesis Example 2 above and 13.981 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 2. A solution consisting of 0.456 g (2 mmol) of sodium 6-maleimidohexanoate, 13.981 g of DMSO, and 1.398 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. 6.991 g of pure water was then added dropwise to obtain a solution containing a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.390 g of compound 12 as a white powder. FT-IR analysis (see Figure 12) confirmed that the nitrate ion, the anion moiety of compound 1, had been replaced with a 6-maleimidohexanoate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 12 was obtained.

[0146] [Synthesis Example 13] <Compound 13 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (anthraquinone-1-sulfonic acid anion) 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.621 g (2 mmol) of sodium anthraquinone-1-sulfonate (Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. 8.745 g of pure water was then added dropwise to obtain a solution containing a yellow precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.625 g of Compound 13 as a yellow powder. The FT-IR analysis results (see FIG. 13) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with an anthraquinone-1-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi element (mass%) was almost consistent with the theoretical value, confirming that Compound 13 was obtained.

[0147] (Synthesis Example 14) <Compound 14 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4(2-[[9,10-dihydro-4-(methylamino)-9,10-dioxo-1-anthracenyl]amino]-5-methylbenzenesulfonic acid anion) 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.889 g (2 mmol) of Alizarin Astrol (2-[[9,10-dihydro-4-(methylamino)-9-10-dioxo-1-anthracenyl]amino]-5-methylbenzenesulfonate sodium, manufactured by Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise with stirring, and the mixture was allowed to react at 25°C for 1 hour. Subsequently, 8.745 g of pure water was added dropwise, resulting in a solution containing a dark blue precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The resulting mixture was then vacuum dried to remove water, yielding 0.340 g of compound 14 as a dark blue powder. The FT-IR analysis results (see FIG. 14) confirmed that the nitrate ion, which is the anion moiety of compound 1, had been replaced with a 2-[[9,10-dihydro-4-(methylamino)-9-10-dioxo-1-anthracenyl]amino]-5-methylbenzenesulfonate ion. Furthermore, the elemental analysis results showed that the Bi element content (mass%) was nearly consistent with the theoretical value, confirming that compound 14 had been obtained.

[0148] (Synthesis Example 15) <Compound 15 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (naphthoquinone-2-diazide-5-sulfonic acid anion) 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.544 g (2 mmol) of sodium naphthoquinone-2-diazide-5-sulfonate (Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 34.980 g of pure water was added dropwise to obtain a solution containing a yellow precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.211 g of Compound 15 as a yellow powder. The FT-IR analysis results (see FIG. 15) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with a naphthoquinone-2-diazide-5-sulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi (mass%) was almost identical to the theoretical value, confirming that Compound 15 was obtained.

[0149] (Synthesis Example 16) <Compound 16 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4-n-octylbenzenesulfonate anion 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.585 g (2 mmol) of sodium 4-n-octylbenzenesulfonate (Tokyo Chemical Industry Co., Ltd.), 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 8.745 g of pure water was added dropwise to obtain a solution containing a yellow-white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.402 g of Compound 16 as a white powder. The FT-IR analysis results (see FIG. 16) confirmed that the nitrate ion, which is the anion moiety of Compound 1, was replaced with a 4-n-octylbenzenesulfonate ion. Furthermore, the elemental analysis results showed that the content of Bi (mass%) was almost identical to the theoretical value, confirming that Compound 16 was obtained.

[0150] (Synthesis Example 17) <Compound 17 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4(4-n-octyloxybenzoate anion) <Synthesis of sodium 4-n-octyloxybenzoate> A 50 ml eggplant-shaped flask was charged with 2.003 g (8 mmol) of 4-n-octyloxybenzoic acid (Tokyo Chemical Industry Co., Ltd.), and an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (Tokyo Chemical Industry Co., Ltd.) in 32 ml of purified water and 20.8 g of 2-propanol was added dropwise and stirred to obtain a colorless, transparent solution of sodium 4-n-octyloxybenzoate. The water and 2-propanol were removed using an evaporator and a vacuum dryer, yielding 2.175 g of sodium 4-n-octyloxybenzoate.

[0151] ≪Compound 17 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (4-n-octyloxybenzoate anion)≫ A solution of Compound 1 (0.700 g, 0.2 mmol) was prepared in a glass beaker with stirring. A solution consisting of 0.545 g (2 mmol) of sodium 4-n-octyloxybenzoate, 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring. The mixture was allowed to react at 25°C for 1 hour, resulting in a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, a process repeated three times. The precipitate was then vacuum dried to remove water, yielding 0.652 g of Compound 17 as a yellow powder. FT-IR analysis (see Figure 17) confirmed that the nitrate ion, the anion moiety of Compound 1, had been replaced with a 4-n-octyloxybenzoate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 17 was obtained.

[0152] (Synthesis Example 18) <Compound 18 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (ketoprofen anion) <Synthesis of ketoprofen sodium> 2.034 g (8 mmol) of ketoprofen (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a 50 ml eggplant-shaped flask. Then, an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) in 32 ml of pure water was added dropwise and stirred to obtain a colorless, transparent aqueous solution of ketoprofen sodium. Water was removed using a vacuum dryer to obtain 2.203 g of ketoprofen sodium.

[0153] ≪Compound 18 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 (ketoprofen anion)≫ 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. A solution consisting of 0.553 g (2 mmol) of ketoprofen sodium obtained above, 17.490 g of DMSO, and 1.749 g of pure water was added dropwise to the beaker with stirring, and the mixture was allowed to react at 25°C for 1 hour. 8.745 g of pure water was then added dropwise to obtain a solution in which a white precipitate formed. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.760 g of Compound 18 as a white powder. FT-IR analysis (see Figure 18) confirmed that the nitrate ion, the anion moiety of Compound 1, had been replaced with a ketoprofen ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 18 was obtained.

[0154] (Synthesis Example 19) <Compound 19 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 [mono(2-acryloyloxyethyl) succinate anion] <Synthesis of sodium mono(2-acryloyloxyethyl) succinate> 1.730 g (8 mmol) of mono(2-acryloyloxyethyl) succinate (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a 50 ml eggplant-shaped flask. Then, an aqueous solution of sodium hydroxide prepared by dissolving 0.320 g (8 mmol) of sodium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) in 17.148 g of pure water was added dropwise and stirred to obtain a colorless and transparent aqueous solution of sodium mono(2-acryloyloxyethyl) succinate (10 mass % aqueous solution).

[0155] ≪Compound 19 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4 [mono(2-acryloyloxyethyl) succinate anion] 0.700 g (0.2 mmol) of Compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of Compound 1. 4.763 g (2 mmol) of a 10% by weight aqueous solution of mono(2-acryloyloxyethyl)sodium succinate was added dropwise to the solution with stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 17.490 g of pure water was added dropwise to obtain a solution containing a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation, and this process was repeated three times. The water was then removed by vacuum drying, yielding 0.245 g of Compound 19 as a white powder. FT-IR analysis (see Figure 19) confirmed that the nitrate ion, the anion moiety of Compound 1, had been replaced with a mono(2-acryloyloxyethyl)succinate ion. Furthermore, the results of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 19 was obtained.

[0156] (Synthesis Example 20) <Compound 20 {[Bi6O5(OH)3(NO3)3]2} 4+ Synthesis of 4[3-(acryloyloxy)propane-1-sulfonic acid anion] 0.700 g (0.2 mmol) of compound 1 obtained in Synthesis Example 1 above and 17.490 g of dimethyl sulfoxide (DMSO) were placed in a glass beaker and stirred to prepare a solution of compound 1. 0.465 g (2 mmol) of potassium 3-(acryloyloxy)propane-1-sulfonate (Tokyo Chemical Industry Co., Ltd.) was added to the solution while stirring, and the mixture was allowed to react at 25°C for 1 hour. Then, 42.470 ml of pure water was added dropwise to obtain a solution containing a white precipitate. The liquid and precipitate were separated by centrifugation. The precipitate was dispersed in 40 ml of pure water and washed by centrifugation. The water was then removed by vacuum drying, yielding 0.247 g of compound 20 as a white powder. FT-IR analysis (see Figure 20) confirmed that the nitrate ion, the anion moiety of compound 1, had been replaced with a 3-(acryloyloxy)propane-1-sulfonate ion. Furthermore, the result of elemental analysis showed that the content of Bi (mass %) was almost identical to the theoretical value, confirming that Compound 20 was obtained.

[0157] The results of elemental analysis of compounds 1 to 20 are shown in Table 1 below.

[0158] [Table 1-1]

[0159] [Table 1-2]

[0160] (Production of Radiation-Sensitive Resist Composition) 0.2 g of each of Compounds 1 to 20 was dissolved in 4.8 g of an organic solvent shown in Table 2 to prepare Radiation-sensitive Resist Compositions 1 to 20.

[0161] (Resist film preparation) The radiation-sensitive resist compositions 1 to 20 obtained above were applied to a 4-inch silicon wafer using a spin coater. Then, the wafer was pre-baked at 130°C for 120 seconds using a hot plate to obtain a resist film with a dry thickness of 40 nm.

[0162] (Radiation exposure and sensitivity evaluation of resist films) The sensitivity of the radiation-sensitive resist composition was evaluated by irradiating it with an electron beam (E-beam), which has a high correlation with extreme ultraviolet (EUV) sensitivity. Using an electron beam exposure device (ELS-7500, manufactured by Elionix Co., Ltd., acceleration voltage 50 kV), the resist film was irradiated with electron beams at two locations on a 250 μm square at different doses. The dose was 500 μC / cm. 2 , and 5000 μC / cm 2 After irradiation, the resist film was developed at 25°C for 1 minute and rinsed with methanol. After rinsing, the film thickness was measured at two irradiated locations to evaluate the sensitivity. For negative resists, the exposure rate was 500μC / cm 2 and 5000 μC / cm 2 If a film with a thickness of 20 nm or more was obtained at both irradiation points, it was marked as ◎. 2 If a film with a thickness of 20 nm or more was obtained only in the irradiated area, it was marked as ◯, and if a film with a thickness of 20 nm or more was not obtained in either of the irradiated areas, it was marked as ×. 2 and 5000 μC / cm 2 When no film remains at both irradiated areas, ◎ is used. 2 The case where no film remained only in the irradiated area was marked with a circle, and the case where film remained in both irradiated areas was marked with an ×.

[0163] The details of the solvents and developers shown in Table 2 below are as follows: NMP: N-methylpyrrolidone DMSO: dimethyl sulfoxide Mixed solvent 1: A mixed solvent of N-methylpyrrolidone and propylene glycol monomethyl ether in a mass ratio of 1:3 Mixed solvent 2: A mixed solvent of N-methylpyrrolidone and propylene glycol monomethyl ether in a mass ratio of 1:9 Mixed solvent 3: 2.38 mass % aqueous solution of TMAH (alkaline developer).

[0164] [Table 2]

[0165] As is clear from Table 2 above, the radiation-sensitive resist compositions of Examples 1 to 18, which contained Compounds 3 to 20, exhibited good sensitivity to electron beams. On the other hand, the radiation-sensitive resist compositions of Comparative Examples 1 and 2, which contained Compounds 1 and 2, exhibited good sensitivity to electron beams at an irradiation dose of 5000 μC / cm 2 However, sufficient sensitivity was not achieved.

[0166] (Comparison of EUV absorption coefficients) Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 7109-7113 describes a method for calculating the EUV linear absorption coefficient of resist polymers and the calculation results. The absorption coefficients of the resist polymers (poly(4-hydroxystyrene), polymethyl methacrylate, Polymer 1, Polymer 7) listed in Tables 1 and 2 of this paper (Comparative Examples 3 to 6), as well as the EUV absorption coefficients of Compound 3 and Compound 10 obtained above (Examples 19 and 20), are shown in Table 3 below.

[0167] The absorption coefficients of Compound 3 and Compound 10 were calculated by the following method. The densities of the resist films of Radiation-Sensitive Resist Compositions 3 and 10 were measured by X-ray reflectivity measurement using an X-ray diffractometer (SmartLab (registered trademark), manufactured by Rigaku Corporation). The density of Compound 3 was 3.9, and the density of Compound 10 was 4.0. Hereinafter, the EUV light absorption coefficient per 1 μm of resist film thickness was calculated from the density of the obtained film and the absorption coefficient of each atom described in BL Henke, EM Gullikson, and JC Davis, "X-ray interactions: photoabsorption, scattering, transmission, and reflection at E=50-30,000 eV, Z=1-92," Atomic Data and Nuclear Data Tables, Vol. 54 (no. 2), pp. 181-342 (July 1993), in the same manner as described in Jpn. J. Appl. Phys., Vol. 38 (1999), pp. 7109-7113.

[0168] [Table 3]

[0169] When the EUV absorption coefficients of each substance were compared, it was found that the EUV absorption coefficients of compounds 3 and 10 shown in Examples 19 and 20 were four or more times higher than the absorption coefficients of the representative resist polymer materials shown in Comparative Examples 3 to 6.

Claims

1. a multivalent ion (a) having a metal cluster structure or a metal oxide cluster structure; an organic ion (b); and an organic solvent, the polyvalent ion (a) contains at least one metal atom selected from the group consisting of indium, antimony, tellurium, and bismuth; The organic ion (b) is selected from the group consisting of a carboxylate anion having 4 or more carbon atoms; a sulfonate anion having 4 or more carbon atoms and having at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group; a phosphonate anion having 4 or more carbon atoms and having at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group; and a phosphonate anion having 6 or more carbon atoms and having at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group. a phenoxide anion having at least one functional group selected from the group consisting of an iodonium cation having 4 or more carbon atoms; a sulfonium cation having 4 or more carbon atoms; an ammonium cation having 4 or more carbon atoms and having at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group; and a pyridinium cation having 5 or more carbon atoms and having at least one functional group selected from the group consisting of a carbon-carbon multiple bond-containing group, a carbonyl group-containing group, an oxime group, an oxime ester group, a halogenated alkyl group, a phosphorus-containing group, a diazo group, and an azide group, a content of the ionic salt in the radiation-sensitive resist composition being 0.5% by mass or more and 30% by mass or less, with the total mass of the composition being 100% by mass;

2. 2. The radiation-sensitive resist composition according to claim 1, wherein the total number of metal atoms in said polyvalent ions (a) is 4 or more and 30 or less.

3. 3. The radiation-sensitive resist composition according to claim 1, wherein the content of at least one metal atom selected from the group consisting of indium, antimony, tellurium, and bismuth is 50 at % or more relative to 100 at % of the total number of metal atoms in the polyvalent ions (a).

4. 4. The radiation-sensitive resist composition according to claim 1, wherein the polyvalent ion (a) has a molecular weight of 600 or more and 9,000 or less.

5. 5. The radiation-sensitive resist composition according to claim 1, wherein the average diameter of the polyvalent ions (a) is 0.5 nm or more and 10 nm or less.

6. 6. The radiation-sensitive resist composition according to claim 1, wherein the polyvalent ions (a) have a valence of three or more.

7. The radiation-sensitive resist composition according to claim 1, wherein the carbon-carbon multiple bond-containing group is at least one group selected from the group consisting of a vinyl group, a stilbene group, a cinnamic acid group, a styrylpyridine group, an anthracene group, and a maleimide group.

8. The radiation-sensitive resist composition according to claim 1, wherein the carbonyl group-containing group is at least one group selected from the group consisting of an anthraquinone group and a phenyl ester group.

9. The radiation-sensitive resist composition according to claim 1, wherein the diazo group is at least one group selected from the group consisting of a diazoalkane group and a diaziridine group.

10. The radiation-sensitive resist composition according to claim 1, wherein the carboxylate anion is a cinnamate anion.

11. The radiation-sensitive resist composition according to claim 1, wherein the iodonium cation is an aryliodonium cation.

12. The radiation-sensitive resist composition according to claim 1, wherein the sulfonium cation is an arylsulfonium cation.

13. 13. The radiation-sensitive resist composition according to claim 1, wherein the organic ion (b) has a molecular weight of 50 or more and 5,000 or less.

14. The radiation-sensitive resist composition according to claim 1, wherein the ionic salt has a total molecular weight of 650 or more and 30,000 or less.

15. 15. The radiation-sensitive resist composition according to claim 1, wherein a ratio of a molecular weight of the polyvalent ion (a) to a total molecular weight of the organic ions (b) [molecular weight of (a) / total molecular weight of (b)] is 0.3 or more and 30 or less.

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