Radiation-resistant composition

Abstract

The present invention provides a means that offers excellent radiation absorption characteristics and dissolution contrast, and can improve properties such as sensitivity, developability, and resolution. [Solution] A radiation-sensitive resist composition comprising an ionic salt (A) containing an anion (a) and an organic cation (b) having a metal chalcogenide cluster structure, and a solvent (B), wherein the anion (a) contains at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, and the organic cation (b) is a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, and carbon A radiation-sensitive resist composition comprising at least one selected from the group consisting of a sulfonium cation having 1 to 30 prime numbers, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms, wherein the content of the ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 20% by mass or more and 100% by mass or less.

Description

[Technical Field]

[0001] This invention relates to a radiation-sensitive resist composition. [Background technology]

[0002] The miniaturization of semiconductor processing, which leads to faster and lower-power semiconductor chips, is constantly in demand, and research and development of lithography technology, which is central to this, is progressing. In recent years, the light source for lithography has been replaced by extreme ultraviolet (EUV), and resist patterns with line widths of 20 nm or less are being obtained. The chemically amplified resists used to obtain these resist patterns have superior sensitivity and resolution compared to materials used in the past, and have been widely adopted since the era of the previous generation of light sources, the excimer laser.

[0003] However, obtaining resist patterns with line widths of 10 nm or less, which will be necessary in the future, presents a problem: the sensitivity and resolution of chemically amplified resists are both insufficient. This is because 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 novel materials (see Patent Document 1). Metal atoms have a significantly higher EUV absorption coefficient compared to carbon and oxygen atoms, which are the main components of organic materials, and have the advantage of being able to capture the energy of photons. Therefore, they have the advantage of superior sensitivity and resolution compared to chemically amplified resists. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-17780 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, even with the technology described in Patent Document 1, the sensitivity and resolution were insufficient, and further improvements in these characteristics were needed.

[0006] Therefore, the present invention aims to provide a means that can improve characteristics such as sensitivity, developability, and resolution, while also exhibiting excellent radiation absorption characteristics and dissolution contrast. [Means for solving the problem]

[0007] The above problems of the present invention can be solved by the following means. That is, according to one embodiment of the present invention, a radiation-sensitive resist composition comprising an ionic salt (A) having a metal chalcogenide cluster structure and an organic cation (b), and a solvent (B), wherein the anion (a) comprises at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, and the organic cation (b) comprises a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, and a phosphonium cation having 1 to 30 carbon atoms. The present invention provides a radiation-sensitive resist composition comprising at least one selected from the group consisting of ion, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms, wherein the content of the ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 20% by mass or more and 100% by mass or less. [Effects of the Invention]

[0008] According to the present invention, a means is provided that can improve properties such as sensitivity, developability, and resolution, while also exhibiting excellent radiation absorption characteristics and dissolution contrast. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the FT-IR spectrum of compound 1 obtained in synthesis example 1. [Figure 2] This figure shows the FT-IR spectrum of compound 2 obtained in synthesis example 2. [Figure 3] This figure shows the FT-IR spectrum of compound 3 obtained in synthesis example 3. [Figure 4] This figure shows the FT-IR spectrum of compound 4 obtained in synthesis example 4. [Figure 5] This figure shows the FT-IR spectrum of compound 5 obtained in synthesis example 5. [Figure 6] This figure shows the FT-IR spectrum of compound 6 obtained in synthesis example 6. [Figure 7] This figure shows the FT-IR spectrum of compound 7 obtained in synthesis example 7. [Figure 8] This figure shows the FT-IR spectrum of compound 8 obtained in synthesis example 8. [Figure 9] This figure shows the FT-IR spectrum of compound 9 obtained in synthesis example 9. [Figure 10] This figure shows the FT-IR spectrum of compound 10 obtained in synthesis example 10. [Figure 11] This figure shows the FT-IR spectrum of compound 11 obtained in synthesis example 11. [Figure 12] This figure shows the FT-IR spectrum of compound 12 obtained in synthesis example 12. [Figure 13] This figure shows the FT-IR spectrum of compound 13 obtained in synthesis example 13. [Figure 14] This figure shows the FT-IR spectrum of compound 14 obtained in synthesis example 14. [Figure 15] This figure shows the FT-IR spectrum of compound 15 obtained in synthesis example 15. [Figure 16] This figure shows the FT-IR spectrum of compound 16 obtained in synthesis example 16. [Figure 17] This figure shows the FT-IR spectrum of compound 17 obtained in synthesis example 17. [Figure 18] This figure shows the FT-IR spectrum of compound 18 obtained in synthesis example 18. [Figure 19] This figure shows the FT-IR spectrum of compound 19 obtained in synthesis example 19. [Figure 20] This figure shows the FT-IR spectrum of compound 20 obtained in synthesis example 20. [Figure 21] This figure shows the FT-IR spectrum of compound 21 obtained in synthesis example 21. [Figure 22] This figure shows the FT-IR spectrum of compound 22 obtained in synthesis example 22. [Figure 23] This figure shows the FT-IR spectrum of compound 23 obtained in synthesis example 23. [Figure 24] This figure shows the FT-IR spectrum of compound 24 obtained in synthesis example 24. [Figure 25] This figure shows the FT-IR spectrum of compound 25 obtained in synthesis example 25. [Figure 26] This figure shows the FT-IR spectrum of compound 26 obtained in synthesis example 26. [Figure 27] This figure shows the FT-IR spectrum of compound 27 obtained in synthesis example 27. [Figure 28] This figure shows the FT-IR spectrum of compound 28 obtained in synthesis example 28. [Figure 29] This figure shows the FT-IR spectrum of compound 29 obtained in synthesis example 29. [Figure 30] This figure shows the FT-IR spectrum of compound 30 obtained in synthesis example 30. [Figure 31] This figure shows the FT-IR spectrum of compound 31 obtained in synthesis example 31. [Figure 32] This figure shows the FT-IR spectrum of compound 32 obtained in synthesis example 32. [Figure 33] This figure shows the FT-IR spectrum of compound 33 obtained in synthesis example 33. [Figure 34]This figure shows the FT-IR spectrum of compound 34 obtained in synthesis example 34. [Figure 35] This figure shows the FT-IR spectrum of compound 35 obtained in synthesis example 35. [Figure 36] This figure shows the FT-IR spectrum of compound 36 obtained in synthesis example 36. [Figure 37] This figure shows the FT-IR spectrum of compound 37 obtained in synthesis example 37. [Figure 38] This figure shows the FT-IR spectrum of compound 38 obtained in synthesis example 38. [Figure 39] This figure shows the FT-IR spectrum of compound 39 obtained in synthesis example 39. [Figure 40] This figure shows the FT-IR spectrum of compound 40 obtained in synthesis example 40. [Figure 41] This figure shows the FT-IR spectrum of compound 41 obtained in synthesis example 41. [Figure 42] This figure shows the FT-IR spectrum of compound 42 obtained in synthesis example 42. [Figure 43] This figure shows the FT-IR spectrum of compound 43 obtained in synthesis example 43. [Figure 44] This figure shows the FT-IR spectrum of compound 44 obtained in synthesis example 44. [Figure 45] This figure shows the FT-IR spectrum of compound 45 obtained in synthesis example 45. [Figure 46] This figure shows the FT-IR spectrum of compound 46 obtained in synthesis example 46. [Figure 47] This figure shows the FT-IR spectrum of compound 47 obtained in synthesis example 47. [Modes for carrying out the invention]

[0010] The present invention relates to a radiation-sensitive resist composition comprising an ionic salt (A) having a metal chalcogenide cluster structure and an organic cation (b), and a solvent (B), wherein the anion (a) comprises at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, and the organic cation (b) comprises a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, and a carbon number The radiation-sensitive resist composition is at least one selected from the group consisting of a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms, wherein the content of the ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 20% by mass or more and 100% by mass or less.

[0011] The radiation-sensitive resist composition according to the present invention, having the above-described configuration, exhibits excellent radiation absorption characteristics and dissolution contrast, and can improve properties such as sensitivity, developability, and resolution.

[0012] The inventors hypothesize the following mechanism by which the problem is solved by the radiation-sensitive resist composition having the above configuration.

[0013] When irradiated with radiation, the anion (a) of the ionic salt (A) changes to a reduced form of the metal chalcogenide, and the organic cation (b) of the ionic salt (A) decomposes. The reduced form of the metal chalcogenide is stabilized by the donation of protons from the solvent (B) and / or the decomposed organic cation (b). This suppresses the reverse reaction in which the reduced form returns to the original metal chalcogenide, and the solubility of the ionic salt containing the reduced form in the developer is significantly different from the solubility of the ionic salt containing the original metal chalcogenide in the developer. Therefore, the radiation-sensitive resist composition according to the present invention exhibits excellent radiation absorption characteristics and solubility contrast, improving properties such as sensitivity, developability, and resolution.

[0014] Furthermore, because organic cation (b) allows for a wide range of structural designs, it becomes easier to further improve sensitivity, developability, resolution, and other properties.

[0015] It should be noted that the above mechanism is based on speculation, and its accuracy does not affect the technical scope of the present invention. Similarly, the accuracy of other speculations in this specification does not affect the technical scope of the present invention.

[0016] Embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments described below. Unless otherwise specified, operations and measurements of physical properties, etc., will be performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40%RH to 50%RH.

[0017] [Radiation-resistant composition] The present invention provides a radiation-sensitive resist composition comprising an ionic salt (A) and a solvent (B). The radiation-sensitive resist composition of the present invention exhibits excellent radiation absorption characteristics and dissolution contrast, as well as excellent properties such as sensitivity, developability, and resolution.

[0018] The radiation-sensitive resist composition of the present invention changes its solubility in a developer solution upon exposure to radiation. The radiation-sensitive resist composition of this embodiment may be a positive-type resist composition in which the exposed portion of the resist film is dissolved and removed to form a positive-type resist pattern, or it may be a negative-type resist composition in which the unexposed portion of the resist film is dissolved and removed to form a negative-type resist pattern. From the viewpoint of better demonstrating the effects of the present invention, it is preferable that it be a positive-type resist composition.

[0019] Furthermore, the radiation-sensitive resist composition of this embodiment may be used for an alkaline development process that uses an alkaline developer for the development process during resist pattern formation, for a solvent development process that uses a developer containing an organic solvent (hereinafter also referred to as an organic developer) for the development process, or for a water development process that uses water for the development process.

[0020] The ionic salt (A) contained in the radiation-sensitive resist composition may be a single type or two or more types.

[0021] [(A) Ionic salt] A radiation-sensitive resist composition according to one embodiment of the present invention comprises an ionic salt (A) containing an anion (a) and an organic cation (b) having a metal chalcogenide cluster structure. The anion (a) and the organic cation (b) are bonded together by an ionic bond to form a salt.

[0022] <Anion(a)> The ionic salt (A) of the present invention has an anion (a) having a metal chalcogenide cluster structure. Here, "metal chalcogenide cluster" refers to an atomic group or molecular group or aggregate formed by the bonding of multiple types of atoms or molecules constituting a metal chalcogenide. Due to having such a cluster structure, the size of the anion (a) is reduced, and when used in a resist, the resolution is improved.

[0023] Anion (a) contains at least one metal atom selected from the group consisting of V (vanadium), Nb (niobium), Ta (tantalum), Mo (molybdenum), and W (tungsten). From the viewpoint of the ease of generating a reducing agent, it is preferable that anion (a) contains at least one metal atom selected from the group consisting of V (vanadium), Mo (molybdenum), and W (tungsten).

[0024] The total number of metal atoms in anion (a) is preferably 4 or more and 50 or less, and more preferably 4 or more and 30 or less. Within this range, the size of anion (a) becomes smaller and the resolution is further improved.

[0025] With respect to 100 at% of the total number of metal atoms in anion (a), the content of at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W is preferably 20 at% or more. With such a content, there will be many metal atoms having a high absorption coefficient for radiation (especially extreme ultraviolet light (EUV)), and the sensitivity is further improved. With respect to 100 at% of the total number of metal atoms in anion (a), the content of at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W is more preferably 45 at% or more, still more preferably 70 at% or more, and particularly preferably 80 at% or more. The upper limit of the content is 100 at%.

[0026] The molecular weight of anion (a) is preferably 600 or more and 9000 or less, and more preferably 1000 or more and 6000 or less. With a molecular weight within such a range, the size of anion (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 an ion or a compound.

[0027] From the viewpoint of further improving resolution, the average diameter of anion (a) is preferably 0.5 nm to 10 nm, and more preferably 0.5 nm to 3 nm. This average diameter can be measured by methods such as single-crystal X-ray structure analysis and dynamic light scattering analysis of the solution.

[0028] The anion (a) constituting the ionic salt (A) according to the present invention may be a single type or a combination of two or more types.

[0029] Anion (a) is preferably at least one selected from the group consisting of anions represented by the following chemical formulas (a-1) to (a-6).

[0030] [ka]

[0031] In the above general formula (a-1), M 1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m1 is an integer between 4 and 60, and multiple M 1 They may be the same or they may be different. X 1 is at least one selected from the group consisting of O, OH, S, and Se, n1 is an integer between 10 and 200, and multiple X 1 They may be the same or they may be different. q1 is an integer between 2 and 40 (inclusive):

[0032] [ka]

[0033] In the above general formula (a-2), M 2-1is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, m2-1 is an integer of 4 or more and 60 or less, and a plurality of M 2-1 may be the same as or different from each other, M 2-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn, m2-2 is an integer of 1 or more and 10 or less. When m2-2 is 2 or more, a plurality of M 2-2 may be the same as or different from each other, X 2 is at least one selected from the group consisting of O, OH, S, and Se, n2 is an integer of 10 or more and 200 or less, and a plurality of X 2 may be the same as or different from each other, q2 is an integer of 2 or more and 40 or less:

[0034]

Chemical formula

[0035] In the above general formula (a-3), M 3 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, m3 is an integer of 4 or more and 60 or less, and a plurality of M 3 may be the same as or different from each other, X 3 is at least one selected from the group consisting of O, OH, S, and Se, n3 is an integer of 10 or more and 200 or less, and a plurality of X 3 may be the same as or different from each other, R 1 is an organic group having 1 to 20 carbon atoms, r1 is an integer of 1 or more and 10 or less. When r1 is 2 or more, a plurality of R1 They may be the same as or different from each other, q3 is an integer from 2 to 40:

[0036]

Chemical formula

[0037] In the general formula (a-4), M 4-1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, m4-1 is an integer from 4 to 60, and for multiple M 4-1 they may be the same as or different from each other, M 4-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn, m4-2 is an integer from 1 to 10. When m4-2 is 2 or more, for multiple M 4-2 they may be the same as or different from each other, X 4 is at least one selected from the group consisting of O, OH, S, and Se, n4 is an integer from 10 to 200, and for multiple X 4 they may be the same as or different from each other, R 2 is an organic group having 1 to 20 carbon atoms, r2 is an integer from 1 to 10. When r2 is 2 or more, for multiple R 2 they may be the same as or different from each other, q4 is an integer from 2 to 40:

[0038]

Chemical formula

[0039] In the general formula (a-5), M 5-1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m5-1 is an integer between 4 and 60, and multiple M 5-1 They may be the same or they may be different. M 5-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m5-2 is an integer between 1 and 10, and if m5-2 is 2 or greater, multiple M 5-2 They may be the same or they may be different. X 5 is at least one selected from the group consisting of O, OH, S, and Se, n5 is an integer between 10 and 200, and multiple X 5 They may be the same or they may be different. h is an integer between 1 and 10, R 3 This is an organic group having 1 to 20 carbon atoms. r3 is an integer between 1 and 10, and if r3 is 2 or greater, multiple R 3 They may be the same or they may be different. q5 is an integer between 2 and 40 (inclusive):

[0040] [ka]

[0041] In the above general formula (a-6), M 6 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m6 is an integer between 4 and 60, and multiple M 6 They may be the same or they may be different. X 6is at least one selected from the group consisting of O, OH, S, and Se, n6 is an integer between 10 and 200, and multiple X 6 They may be the same or they may be different. Z is an inorganic functional group comprising at least one atom selected from the group consisting of nitrogen, phosphorus, and sulfur atoms, and an oxygen atom. p is an integer between 1 and 10, and if p is 2 or greater, multiple Zs may be the same or different from each other. q6 is an integer between 2 and 40 (inclusive).

[0042] X in the above general formula (a-1) 1 , X in the above general formula (a-2) 2 , X in the above general formula (a-3) 3 , X in the above general formula (a-4) 4 , X in the above general formula (a-5) 5 , and X in the above general formula (a-6) 6 These are chalcogen elements or groups containing chalcogen elements. They are directly bonded to at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, and contribute to the stabilization of the cluster structure.

[0043] In the above general formula (a-2), M 2-2 , M in the above general formula (a-4) 4-2 , and M in the above general formula (a-5) 5-2 These are also called modifying elements, and although they are not directly bonded to at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W, they contribute to the stabilization of the cluster structure. Note that S, which is included in chalcogen elements, can also be used as a modifying element.

[0044] In the above general formula (a-3), R 1 , R in the above general formula (a-4) 2 , and R in the above general formula (a-5) 3This refers to an organic group having 1 to 20 carbon atoms. Specific examples of organic groups include, for example, chain-like hydrocarbon groups such as methyl and ethyl groups; cyclic hydrocarbon groups such as cyclohexyl and phenyl groups; chain-like heteroatom-containing groups such as trimethylolethane, ethylenecarbonyloxy, methylphosphonic acid, and ethylphosphonic acid groups; and heterocyclic groups such as pyridinyl and 1,10-phenanthrolinyl groups.

[0045] In the general formula (a-6) above, Z is an inorganic functional group comprising at least one atom selected from the group consisting of nitrogen, phosphorus, and sulfur atoms, and an oxygen atom. Examples of such functional groups include the nitroso group (NO), PO4 group, HPO4 group, SO3 group, etc.

[0046] From the viewpoint of reducing the size of the ionic salt (A) and improving resolution, it is preferable that q1 in the above general formula (a-1), q2 in the above general formula (a-2), q3 in the above general formula (a-3), q4 in the above general formula (a-4), q5 in the above general formula (a-5), and q6 in the above general formula (a-6) are each independent integers between 3 and 15.

[0047] A more specific example of the anion (a) represented by the general formula (a-1) above is, for example, [Nb6O 19 ] 8- [Nb7O 22 ] 9- [Nb 10 O 28 ] 6- [Ta6O 19 ] 8- [Ta 10 O 28 ] 6- [Mo6O 19 ] 2- [W6O 19 ] 2- [W7O 24 ] 6- [W 10 O 32 ] 4- [W 10 O 34 ] 8- [Mo7O24 6- ,[Mo8O 26 4- ,[Mo 10 O 34 8- ,[W 12 O 40 (OH)2] 10- ,[W 12 O 38 (OH)2] 6- ,[V4O 12 4- ,[V 10 O 28 6- ,[V 12 O 32 4- ,[V 13 O 34 4- ,[V 18 O 42 12- ,[NbW5O 19 3- ,[Nb4W2O 19 6- ,[V2W4O 19 4- ,[NbVW4O 19 4- ,[V5Mo8O 40 7- ,[W6O 18 S] 2- ,[W3OS8] 2- ,[W4S 12 2- and the like can be mentioned.

[0048] As more specific examples of the anion (a) represented by the general formula (a-2), for example, [TeMo6O 24 6- ,[CoW6As6O 30 4- ,[SW 12 O 40 2- ,[PW 12 O 40 3- ,[AsW 12 O 40 3- ,[SiW 12 O 40 ​​​​​​​​​​​​​​​​​​​​4- [GeW 12 ZERO 40 ] 4- [BW 12 ZERO 40 ] 5- [AlW 12 ZERO 40 ] 5- [GaW 12 ZERO 40 ] 5- [FeW 12 ZERO 40 ] 5- [ZnW 12 ZERO 40 ] 6- [CoW 12 ZERO 40 ] 6- [SMO] 12 ZERO 40 ] 2- [PM] 12 ZERO 40 ] 3- [Today 12 ZERO 40 ] 3- [SiMo 12 ZERO 40 ] 4- [GeMo] 12 ZERO 40 ] 4- [SiMo2W 10 ZERO 40 ] 4- [SiVW 11 ZERO 40 ] 5- ,[SiMo2VW9O 40 ] 5- [SiW 11 ZERO 39 ] 8- [PW 11 ZERO 39 ] 8- [B3W 39 ZERO 132 ] 21- [AsW9O 33 ] 9- [P2W 18 ZERO 62 ] 6- [As2W 18 ZERO 62 ] 6- [S2W 18 ZERO 62 ]4- [P2Mo 18 O 62 ] 6- [As2Mo 18 O 62 ] 6- [S2Mo 18 O 62 ] 4- [AgP5W 30 O 110 ] 14- [Sn8W 18 O 66 ] 8- [Sn3W 18 Nut2O 68 ] 14- [Sn3W 18 P2O 68 ] 12- [SnW 12 O 42 ] 10- [Te 10 W 28 O 118 ] 28- [Te2W 18 Cu3O 69 ] 16- [Te4W 20 O 80 ] 24- [Te9W 28 O 112 ] 24- [Te2W 58 O 198 ] 36- [TeW 18 O 63 ] 8- [TeW 18 O 62 ] 10- [TeW6O 24 ] 6- [Te2W 17 O 61 ] 12- [TeW 15 O 54 ] 14- [InW 11 PO 40 ] 8- [InW 11 SiO 40 ] 9- Examples include, etc.

[0049] A more specific example of the anion (a) represented by the general formula (a-3) above is, for example, [Mo6O 17 (NC6H5)2] 2- [Mo8O 24 {CH3C(CH2O)3}2] 6- Examples include, etc.

[0050] A more specific example of the anion (a) represented by the general formula (a-4) above is, for example, [InW3O4(C2H4COO)8]. 22- [MnMo6O 18 {CH3C(CH2O)3}2] 3- [ZnMo6O 18 {CH3C(CH2O)3}2] 4- [PW9O 30 (C2H5PO3)2] 6- Examples include, etc.

[0051] A more specific example of the anion (a) represented by the general formula (a-5) above is, for example, {ZnW 12 O 40 [Cu(phen)(H2O)]2} 2- These are some examples. In the formula, (phen) is an abbreviation for the 1,10-phenanthrolinyl group.

[0052] A more specific example of the anion (a) represented by the general formula (a-6) above is, for example, [Mo6O 18 (NO)] 3- [Mo5O 15 (PO4)2] 6- [W5O 15 (PO4)2] 6- [Mo5O 15 (HPO4)2] 4- [Mo5O 15 (SO3)2] 4- Examples include, etc.

[0053] Among these anions (a), [Mo6O 19 ] 2- [W6O 19 ] 2- [W7O24 ] 6- 、[W 10 O 32 ] 4- 、[W 10 O 34 ] 8- 、[Mo7O 24 ] 6- 、[Mo8O 26 ] 4- 、[Mo 10 O 34 ] 8- 、[W 12 O 40 (OH)2] 10- 、[W 12 O 38 (OH)2] 6- 、[V4O 12 ] 4- 、[V 10 O 28 ] 6- 、[V 12 O 32 ] 4- 、[V 13 O 34 ] 4- 、[V 18 O 42 ] 12- 、[NbW5O 19 ] 3- 、[Nb4W2O 19 ] 6- 、[V2W4O 19 ] 4- 、[NbVW4O 19 ] 4- 、[V5Mo8O 40 ] 7- 、[W6O 18 S] 2- 、[W3OS8] 2- 、[W4S 12 ] 2- 、[TeMo6O 24 ] 6- 、[CoW6As6O 30 ] 4- 、[SW 12 O 40 ] 2- 、[PW 12 O 40 ] 3- 、[AsW 12 O 40 ] 3-,[SiW 12 The 40 ] 4- ,[GeW 12 The 40 ] 4- [BW 12 The 40 ] 5- ,[AlW 12 The 40 ] 5- [GaW 12 The 40 ] 5- ,[FeW 12 The 40 ] 5- ,[ZnW 12 The 40 ] 6- ,[CoW 12 The 40 ] 6- [SMO] 12 The 40 ] 2- [PMo 12 The 40 ] 3- [AsMo 12 The 40 ] 3- [SiMo 12 The 40 ] 4- [GeMo 12 The 40 ] 4- ,[SiMo2W 10 The 40 ] 4- ,[SiVW 11 The 40 ] 5- ,[SiMo2VW9O 40 ] 5- ,[SiW 11 The 39 ] 8- [PW 11 The 39 ] 8- ,[B3W 39 The 132 ] 21- ,[AsW9O 33 ] 9- ,[P2W 18 The 62 ] 6- ,[As2W 18 The 62 ] 6-[S2W 18 ZERO 62 ] 4- [P2Mo] 18 ZERO 62 ] 6- [As2Mo 18 ZERO 62 ] 6- [S2Mo] 18 ZERO 62 ] 4- [AgP5W 30 ZERO 110 ] 14- [Sn8W 18 ZERO 66 ] 8- ,[Sn3W 18 Si2O 68 ] 14- ,[Sn3W 18 P2O 68 ] 12- [SnW 12 ZERO 42 ] 10- [The 10 W 28 ZERO 118 ] 28- [Te2W 18 Cu3O 69 ] 16- [Te4W 20 ZERO 80 ] 24- [Te9W 28 ZERO 112 ] 24- [Te2W 58 ZERO 198 ] 36- [TW 18 ZERO 63 ] 8- [TW 18 ZERO 62 ] 10- [TeW6O 24 ] 6- [Te2W 17 ZERO 61 ] 12- [TW 15 ZERO 54 ] 14- [InW 11 NIGHT 40 ] 8- [InW 11 SiO 40 ] 9- [Mo6O17 (NC6H5)2] 2- [Mo8O 24 {CH3C(CH2O)3}2] 6- [InW3O4(C2H4COO)8] 22- [MnMo6O 18 {CH3C(CH2O)3}2] 3- [ZnMo6O 18 {CH3C(CH2O)3}2] 4- [PW9O 30 (C2H5PO3)2] 6- , {ZnW 12 O 40 [Cu(phen)(H2O)]2} 2- [Mo6O 18 (NO)] 3- [Mo5O 15 (PO4)2] 6- [W5O 15 (PO4)2] 6- [Mo5O 15 (HPO4)2] 4- [Mo5O 15 (SO3)2] 4- It is preferable.

[0054] Among these anions (a), [Mo6O 19 ] 2- [W6O 19 ] 2- [W 10 O 32 ] 4- [Mo7O 24 ] 6- Now PW 12 O 40 ] 3- [SiW 12 O 40 ] 4- [PMo 12 O 40 ] 3- This is preferable.

[0055] Representative structures of metal chalcogenide clusters include the Keggin structure, the Wells-Dawson structure, and the Anderson-Evans-Perloff structure. While the above structures are examples of cluster structures for anion (a), the cluster structures of anion (a) are not limited to these.

[0056] <Organic cation (b)> The organic cation (b) according to the present invention is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms. Regardless of the type, the number of carbon atoms in the organic cation (b) is 30 or less. However, if the number of carbon atoms exceeds 30, the proportion of metal atoms with a high absorption coefficient for radiation (especially extreme ultraviolet (EUV)) in the ionic salt (A) decreases, resulting in reduced sensitivity.

[0057] Examples of organic groups that the organic cation (b) may possess include linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. These organic groups may contain heteroatoms. Linear hydrocarbon groups may be linear or branched. Linear hydrocarbon groups and alicyclic hydrocarbon groups may be saturated or unsaturated. Alicyclic hydrocarbon groups and aromatic hydrocarbon groups may be monocyclic or polycyclic. Furthermore, these organic groups may be substituted with substituents such as alkyl groups, alkenyl groups, alkoxy groups, cycloalkyloxy groups, aryl groups, arylalkyl groups, aryloxy groups, arylalkoxy groups, heterocyclic groups, alkylidene groups, acyl groups, acyloxy groups, amino groups, silyl groups, carboxyl groups, sulfo groups, cyano groups, nitro groups, thiol groups, hydroxyl groups, and halogen groups.

[0058] From the viewpoint of having high proton-donating properties, it is preferable that the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms. Furthermore, from a similar viewpoint, it is more preferable that the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms.

[0059] If the radiation-sensitive resist composition is a negative-type resist composition, it is also preferable to use a quaternary ammonium cation having 2 to 30 carbon atoms as the organic cation (b).

[0060] The organic cation (b) according to the present invention may be a monovalent ion or a polyvalent ion with two or more valencies, but it is preferable that it be monovalent from the viewpoint of resolution. Furthermore, the organic cation (b) constituting the ionic salt (A) according to the present invention may be a single type or a combination of two or more types.

[0061] Specific examples of the organic cation (b) according to the present invention include the following cations.

[0062] Examples of secondary ammonium cations with 2 to 30 carbon atoms: Dimethylammonium cation, Diethylammonium cation, N-ethylmethylammonium cation, Dipropylammonium cation, Dibutylammonium cation, Azetidinium cation, Pyrrolidinium cation, N-methylpropylammonium cation, N-methylethanolammonium cation, Piperidinium cation.

[0063] Examples of tertiary ammonium cations with 2 to 30 carbon atoms: Trimethylammonium cation, Triethylammonium cation, Triethanolammonium cation, N,N-dimethylethylammonium cation, 1-Methylpyrrolidinium cation, Tris[2-(2-methoxyethoxy)ethyl]ammonium cation, Trihexylammonium cation, Triheptylammonium cation, Anilinium cation, N,N,N',N'-tetramethylethylenediammonium cation, Triethanolammonium cation, N,N-dimethylanilinium cation, Methyldiphenylammonium cation, N,N,2,4,6-pentamethylanilinium cation, N,N-dimethyl-1-naphthylammonium cation, N,N-dipropylanilinium cation, 1-phenylpiperidinium cation, Triethylenediammonium cation.

[0064] Examples of quaternary ammonium cations with 2 to 30 carbon atoms: Tetramethylammonium cation, 2-hydroxyethyltrimethylammonium cation, Tetraethylammonium cation, 1,1-dimethylpiperidinium cation, Triethylmethylammonium cation, Trimethylphenylammonium cation, 2-Hydroxypropyltrimethylammonium cation, 5-Azonia spiro[4.4]nonancation, diallyldimethylammonium cation, Trimethylvinylammonium cation, benzyltrimethylammonium cation, Bis(2-hydroxyethyl)dimethylammonium cation, 1-Butyl-1-methylpyrrolidinium cation, Acetylcholine cation, Trimethylpropylammonium cation, N,N-dimethylmethyleneammonium cation, [2-(acryloyloxy)ethyl]trimethylammonium cation, benzyltriethylammonium cation, 1-ethyl-1-methylpyrrolidinium cation, Metacholine, Butyltrimethylammonium cation, Tetrapropylammonium cation, Tetrabutylammonium cation, (3-acrylamidopropyl)trimethylammonium cation, Trimethyl-2-methacryloyloxyethylammonium cation, n-octyltrimethylammonium cation, 1-methyl-1-propylpyrrolidinium cation, N-benzyl-2-((4-iodobenzoyl)oxy)-N,N-dimethylethane-1-aminium cation, 2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium cation, 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium cation.

[0065] Examples of phosphonium cations with 1 to 30 carbon atoms: Tetraethylphosphonium cation, Tetrabutylphosphonium cation, Tributyl(cyanomethyl)phosphonium cation, Methyltriphenylphosphonium cation, Ethyltriphenylphosphonium cation, (formylmethyl)triphenylphosphonium cation, Tributyl(methyl)phosphonium cation, (methoxymethyl)triphenylphosphonium cation, Tetraphenylphosphonium cation, Acetonyltriphenylphosphonium cation, Butyltriphenylphosphonium cation, Triphenylpropargylphosphonium cation, Methoxycarbonylmethyl(triphenyl)phosphonium cation, Amiltriphenylphosphonium cation, Tetrakis(hydroxymethyl)phosphonium cation, Tributyl-n-octylphosphonium cation, benzyltriphenylphosphonium cation, Triphenylpropylphosphonium cation, Allyltriphenylphosphonium cation, Cyclopropyltriphenylphosphonium cation, Benzyltriphenylphosphonium cation.

[0066] Examples of sulfonium cations with 1 to 30 carbon atoms: Triphenylsulfonium cation, Trimethylsulfonium cation, Triethylsulfonium cation, Tributylsulfonium cation, (2-carboxyethyl)dimethylsulfonium cation, 4-hydroxyphenyldimethylsulfonium cation, Diphenyl(methyl)sulfonium cation, Dimethyl(phenethyl)sulfonium cation, 5-Ethenylthianthrenium cation, (Difluoromethyl)bis(2,5-dimethylphenyl)sulfonium cation, Tri-p-tolylsulfonium cation, Benzyl(4-hydroxyphenyl)methylsulfonium cation, Dimethyl(trifluoromethyl)sulfonium cation, Diphenyl[4-(phenylthio)phenyl]sulfonium cation, (Thiodi-4,1-phenylene)bis(diphenylsulfonium) cation.

[0067] Examples of iodonium cations with 1 to 30 carbon atoms: Diphenyliodonium cation, Bis(4-tert-butylphenyl)iodonium cation, Bis(4-methylphenyl)iodonium cation, Bis(4-fluorophenyl)iodonium cation, (4-nitrophenyl)(phenyl)iodonium cation, (4-methylphenyl)(2,4,6-trimethylphenyl)iodonium cation, (2-methylphenyl)(2,4,6-trimethylphenyl)iodonium cation, (3-methylphenyl)(2,4,6-trimethylphenyl)iodonium cation, (4-isobutylphenyl)(p-tolyl)iodonium cation, Phenyl[3-(trifluoromethyl)phenyl]iodonium cation, Bis(2,4,6-trimethylphenyl)iodonium cation, [4-(trifluoromethyl)phenyl](2,4,6-trimethylphenyl)iodonium cation, [3-(trifluoromethyl)phenyl](2,4,6-trimethylphenyl)iodonium cation, Phenyl(2,4,6-trimethoxyphenyl)iodonium cation, (3-bromophenyl)(mesityl)iodonium cation, Bis(4-bromophenyl)iodonium cation, 4-Biphenylyl(2,4,6-trimethoxyphenyl)iodonium cation, (5-Fluoro-2-nitrophenyl)(2,4,6-trimethoxyphenyl)iodonium cation, [(4-trifluoromethyl)phenyl](2,4,6-trimethoxyphenyl)iodonium cation, (3,5-dichlorophenyl)(2,4,6-trimethoxyphenyl)iodonium cation, [4-Fluoro-3-(trifluoromethyl)phenyl](2,4,6-trimethoxyphenyl)iodonium cation, [4-(bromomethyl)phenyl](2,4,6-trimethoxyphenyl)iodonium cation, [4-(octyloxy)phenyl](phenyl)iodonium cation, [4-[(2-hydroxytetradecyl)oxy]phenyl]phenyliodonium cation, (4-isopropylphenyl)(p-tolyl)iodonium cation, 4-Isopropyl-4'-methyldiphenyliodonium cation.

[0068] Examples of pyridinium cations with 5 to 30 carbon atoms: Pyridinium cation, 1-methylpyridinium cation, 1-ethylpyridinium cation, 1-Propylpyridinium cation, 1-Acetonylpyridinium cation, 1-Butylpyridinium cation, 1-Butyl-4-methylpyridinium cation, 1-Butyl-3-methylpyridinium cation, 1-ethyl-2-methylpyridinium cation, 1-ethyl-4-methylpyridinium cation, 1-(3-sulfopropyl)-2-vinylpyridinium cation, 4-dimethylamino-1-neopentylpyridinium cation, 1,4-dimethylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 2-chloro-1-methylpyridinium cation, 1,1'-dimethyl-4,4'-bipyridinium cation, 4-tert-butyl-1-(3-sulfopropyl)pyridinium cation, 1-Ethyl-3-(hydroxymethyl)pyridinium cation, 2-bromo-1-ethylpyridinium cation, 1-(2,4-dinitrophenyl)pyridinium cation, 2-fluoro-1-methylpyridinium cation, 1-Dodecylpyridinium cation, 1-Ethylquinolinium cation, 1-Ethyl-4-(methoxycarbonyl)pyridinium cation, 10-methylacridinium cation, 1-Ethylquinaldinium cation, 1-Hexylpyridinium cation, 1-Tetradecylpyridinium cation, 2-benzyloxy-1-methylpyridinium cation, 1-Hexadecyl-4-methylpyridinium cation, Cetylpyridinium cation, Hexadecylpyridinium cation, 10-methyl-9-phenylacridinium cation, 1,1'-Diethyl-4,4'-Bipyridinium cation, 1,1'-Dibenzyl-4,4'-Bipyridinium cation.

[0069] Examples of imidazolium cations with 3 to 30 carbon atoms: Imidazolium cation, 1,3-dimethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-allyl-3-methylimidazolium cation, 1-methyl-3-propylimidazolium cation, 1-(2-hydroxyethyl)-3-methylimidazolium cation, 1-Butyl-3-methylimidazolium cation, 1-Butyl-2,3-dimethylimidazolium cation, 1-Hexyl-3-methylimidazolium cation, 1-benzyl-3-methylimidazolium cation, 2-Chloro-1,3-dimethylimidazolinium cation, 1,3-Diisopropylimidazolium cation, 1-methyl-3-n-octylimidazolium cation, 3-butyl-1-vinylimidazolium cation, 1-methyl-3-pentylimidazolium cation, 1,3-di-tert-butylimidazolium cation, 1,3-dicyclohexylimidazolium cation, 1,3-Diisopropylbenzimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-Hexadecyl-3-methylimidazolium cation, 1-Carbobenzoxy-3-methylimidazolium cation, 1-Methyl-3-[6-(methylthio)hexyl]imidazolium cation, 1,1'-(2,6-pyridinediyl)bis(3-methylimidazolium) cation, 3-ethyl-1-vinylimidazolium cation, 3,3'-Methylenebis(1-tert-butyl-3-imidazolium) cation, 1,3-di(1-adamantyl)imidazolium cation, 1,3-Bis(2,6-diisopropylphenyl)imidazolium cation.

[0070] Examples of diazonium cations with 1 to 30 carbon atoms 4-Methoxybenzenediazonium cation, 4-Nitrobenzenediazonium cation, 4-bromobenzenediazonium cation, 4-aminodiphenylaminediazonium cation, 4-(pentafluorosulfanyl)phenyldiazonium cation, 4-[N-(4-methoxyphenyl)amino]benzenediazonium cation.

[0071] Examples of guanidinium cations with 1 to 30 carbon atoms: Guanidia cation, 1,1,3,3-tetramethylguanidinium cation, 1-Acetylguanidinium cation, 1-Methylguanidinium cation, 1,3,4,6,7,8-Hexahydro-2H-pyrimido[1,2-a]pyrimidinium cation, 1,3,4,6,7,8-Hexahydro-1-methyl-2H-pyrimido[1,2-a]pyrimidinium cation, 2-tert-butyl-1,1,3,3-tetramethylguanidinium cation, 1,3-diphenylguanidinium cation, 1,3-di-o-tolylguanidinium cation.

[0072] Examples of hydrazinium cations with 1 to 30 carbon atoms: 1,1-dimethylhydrazinium cation, 1-methyl-1-phenylhydrazinium cation, Phenylhydrazinium cation, 1,1-Diphenylhydrazinium cation, 1-acetyl-2-phenylhydrazinium cation, 4-nitrophenylhydrazinium cation, 2-methylphenylhydrazinium cation, 4-Methoxyphenylhydrazinium cation, 2-Methoxyphenylhydrazinium cation, 3-(trifluoromethyl)phenylhydrazinium cation, 1,2-diphenylhydrazinium cation, 1-Naphthylhydrazinium cation.

[0073] Among these organic cations (b), the following organic cations are preferred.

[0074] Triethylammonium cation, Triethanolammonium cation, Tris[2-(2-methoxyethoxy)ethyl]ammonium cation, Triheptylammonium cation, N,N,N',N'-tetramethylethylenediammonium cation, N,N-dimethylanilinium cation, N,N,2,4,6-pentamethylanilinium cation, 1-phenylpiperidinium cation, Triethylenediammonium cation, Tetrabutylammonium cation, N-benzyl-2-((4-iodobenzoyl)oxy)-N,N-dimethylethane-1-aminium cation, 2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium cation, 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium cation, Methyltriphenylphosphonium cation, Tetraphenylphosphonium cation, Triphenylsulfonium cation, Diphenyliodonium cation, Bis(4-tert-butylphenyl)iodonium cation, (4-nitrophenyl)(phenyl)iodonium cation, (4-methylphenyl)(2,4,6-trimethylphenyl)iodonium cation, Phenyl[3-(trifluoromethyl)phenyl]iodonium cation, [3-(trifluoromethyl)phenyl](2,4,6-trimethylphenyl)iodonium cation, Phenyl(2,4,6-trimethoxyphenyl)iodonium cation, Pyridinium cation, 1-methylpyridinium cation, Imidazolium cation, 1,3-dimethylimidazolium cation, 4-Methoxybenzenediazonium cation, 1,1,3,3-tetramethylguanidinium cation, 1,3-di-o-tolylguanidinium cation, 1,1-Diphenylhydrazinium cation.

[0075] In addition to the organic cation (b), the ionic salt (A) also contains protons (hydrogen cations; H) as cationic components. + ) may have.

[0076] From the viewpoint of reducing the size of the ionic salt and further improving resolution, the molecular weight of the organic cation (b) is preferably 50 to 5000, and more preferably 100 to 1000.

[0077] <Specific examples of ionic salts> Specific examples of the ionic salt (A) of the present invention include the following compounds.

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] The ionic salt (A) contained in the radiation-sensitive resist composition of the present invention may be a single type or two or more types.

[0086] Among these ionic salts (A), the following compounds are considered preferred ionic salts (A).

[0087] [ka]

[0088] [ka]

[0089] <Method for producing ionic salts> The method for producing the ionic salt (A) used in the present invention is not particularly limited, and for example, a method can be used in which a compound having an anion (a) containing a metal chalcogenide cluster is mixed with a compound having an organic cation (b), and a salt exchange reaction is carried out. This salt exchange reaction can be easily carried out by known methods, and if necessary, it can be purified by conventional methods such as filtration, distillation, extraction, washing with water or organic solvent, crystallization, treatment with acid, treatment with alkali, and column chromatography. These purification methods are preferably repeated in order to adjust the impurity concentration of the composition to a desired range.

[0090] The compounds having the above-mentioned anion (a) and organic cation (b) may be commercially available or synthesized. For the synthesis methods of these compounds, conventionally known methods can be appropriately referred to and adopted.

[0091] Compounds having an anion (a) and compounds having an organic cation (b) can be purified by the following means if necessary. Purification methods include filtration, distillation, extraction, washing with water or organic solvent, recrystallization, crystallization, treatment with acid, treatment with alkali, and purification by column chromatography, and can be appropriately selected from these depending on the nature 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 methods are preferably repeated in order to adjust the impurity concentration of the composition to a desired range.

[0092] The structure (composition) of the ionic salt according to 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 structure analysis, powder X-ray diffraction (PXRD) analysis, liquid chromatography (LC) analysis, size exclusion chromatography (SEC) analysis, thermal analysis, etc. Details of the confirmation method are as described in the examples.

[0093] From the viewpoint of improving resolution, the ionic salt (A) according to the present invention preferably has a total molecular weight of 650 to 30,000, and more preferably 900 to 15,000.

[0094] Furthermore, from the viewpoint of radiation absorption and photosensitivity, the ionic salt (A) according to the present invention preferably has a ratio of the molecular weight of the anion (a) to the total molecular weight of the organic cation (b) [molecular weight of (a) / total molecular weight of (b)] of 0.3 or more and 30 or less, and preferably 0.5 or more and 10 or less.

[0095] Note that the total molecular weight of organic cation (b) refers to the total molecular weight of all organic cations (b) contained in the ionic salt. For example, if five monovalent organic cations (b) are bonded to a pentavalent anion (a), the total molecular weight of these five cations is the total molecular weight of organic cation (b).

[0096] The content of ionic salt (A) in the total solid content of the radiation-sensitive resist composition of the present invention is 20% by mass or more and 100% by mass or less. If the content of ionic salt (A) in the total solid content of the radiation-sensitive resist composition is less than 20% by mass, the dissolution contrast decreases. Preferably, the content of ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 50% by mass or more and 100% by mass or less, and more preferably 80% by mass or more and 100% by mass or less.

[0097] The content of ionic salt (A) in the radiation-sensitive resist composition of the present invention (the total amount if there are two or more types) is preferably 0.5% by mass or more and 30% by mass or less, based on 100% by mass of the total mass of the radiation-sensitive resist composition. More preferably, the content is 2% by mass or more and 20% by mass or less.

[0098] [Solvent (B)] The solvent (B) 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 (A) and any optional components that may be included. The solvent (B) may be the same solvent used when synthesizing the ionic salt (A). The solvent (B) may be a single solvent or a combination of two or more solvents. Alternatively, a mixed solvent of water and an organic solvent may be used.

[0099] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, sulfoxide-based solvents, and hydrocarbon-based solvents.

[0100] More specifically, alcoholic solvents include, for example, 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, trimethyl alcohol Monoalcohol solvents such as phenyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol; polyhydric alcohol 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 include polyhydric alcohol partial ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether (2-butoxyethanol), 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.

[0101] 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; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0102] Examples of ketone solvents include linear 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.

[0103] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methyl-2-pyrrolidone; and chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0104] 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, and propylene glycol acetate. Examples include polyhydric alcohol partial ether carboxylate solvents such as propyl monopropyl ether, propylene glycol acetate monobutyl ether, dipropylene glycol acetate monomethyl ether, and dipropylene glycol acetate monoethyl ether; lactone solvents such as γ-butyrolactone and δ-valerolactone; carbonate solvents such as dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate; lactic acid ester solvents such as methyl lactate, ethyl lactate, n-butyl lactate, and n-amyl lactate; and glycol diacetate, methoxytriglyceryl 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.

[0105] Examples of sulfoxide solvents include dimethyl sulfoxide and diethyl sulfoxide.

[0106] 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.

[0107] Among these solvents (B), alcohol-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and sulfoxide-based solvents are preferred. More preferably, solvent (B) is at least one selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monoethyl ether, cyclohexanone, propylene glycol acetate monomethyl ether, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, ethyl lactate, and dimethyl sulfoxide.

[0108] <Optional ingredients> In addition to the ionic salt (A) and solvent (B) described above, the radiation-sensitive resist composition according to the present invention may include, as an optional component, for example, a radiation-sensitive acid generator, a fluorine atom-containing polymer, a surfactant, a crosslinking agent, a leveling agent, a colorant, or a combination thereof.

[0109] Surfactants improve coating properties, striation properties, and developability. Specific examples of surfactants 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. Surfactants may be commercially available or synthetically produced. Examples of commercially available surfactants include, for example, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75 and No. 95 (both manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, and EF352 (both manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac® F171, F173, R40, R41, and R43 (all manufactured by DIC Corporation), Fluorad® FC430 and FC431 (both manufactured by 3M), Asahiguard AG710 (manufactured by AGC Inc.), Surflon® S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and SC-106 (all manufactured by AGC Seimi Chemical Co., Ltd.).

[0110] Examples of crosslinking agents include, but are not limited to, melamine-based crosslinking agents, substituted urea-based crosslinking agents, or polymer-based crosslinking agents. As crosslinking agents having at least two crosslinking substituents, for example, compounds such as methoxymethylated glycoluryl, butoxymethylated glycoluryl, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, or methoxymethylated thiourea can be used.

[0111] Leveling agents are used to improve the flatness of the coating film during printing (coating), and commercially available, known leveling agents can be used.

[0112] Furthermore, the radiation-sensitive resist composition of the present invention may use a silane coupling agent as an optional component to improve adhesion to the substrate. Examples of silane coupling agents include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane; carbon-carbon unsaturated bond-containing silane compounds such as 3-methacryloxypropyltrimethoxysilane, 3-acryloxpropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane; and trimethoxy[3-(phenylamino)propyl]silane.

[0113] The amount of these optional components used can be easily adjusted according to the desired physical properties and can be set as appropriate. Furthermore, these optional components can be used individually or in combination of two or more.

[0114] The method for producing the radiation-sensitive resist composition of the present invention is not particularly limited, and includes, for example, a method of mixing an ionic salt (A) and an optional component, which may be added as needed, in a solvent (B). The temperature and time during mixing are not particularly limited. Filtration may be performed after mixing, if necessary.

[0115] [Pattern formation method] The pattern formation method using the radiation-sensitive resist composition according to the present invention is not particularly limited. However, according to one preferred embodiment, the method comprises the steps of: coating the radiation-sensitive resist composition of the present invention onto 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 "development step"). Because this pattern formation method uses the radiation-sensitive resist composition of the present invention, it is possible to form a pattern that is highly sensitive, highly developable, and has high resolution. Each step will be described below.

[0116] <Coating Process> In this process, a radiation-sensitive resist composition is coated onto one side of the substrate. This forms a resist film. The coating method is not particularly limited and includes methods such as spin coating, spray coating, dip coating, knife-edge coating, inkjet printing, and screen printing. Examples of substrates include silicon wafers and aluminum-coated wafers. Specifically, after coating the radiation-sensitive resist composition to a predetermined thickness, the solvent in the coating film is evaporated by pre-baking (PB) as needed.

[0117] The lower limit of the resist film thickness after pre-baking is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. The upper limit of the resist film thickness after pre-baking is preferably 1,000 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less.

[0118] The lower limit of the pre-bake temperature is preferably 60°C or higher, and more preferably 80°C or higher. The upper limit of the pre-bake temperature is preferably 150°C or lower, and more preferably 140°C or lower. The lower limit of the pre-bake time is preferably 5 seconds or higher, and more preferably 10 seconds or higher. The upper limit of the pre-bake time is preferably 600 seconds or lower, and more preferably 300 seconds or lower.

[0119] <Exposure process> In this process, the film formed by the coating process described above is exposed to light. This exposure may be performed by irradiating the film with radiation through a liquid immersion medium such as water, via a mask having a desired pattern. Examples of such 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, the irradiation of these radiations may be collectively referred to as "exposure."

[0120] Among these types of radiation, extreme ultraviolet (EUV) or electron beams are more preferred.

[0121] Various types of light sources can be used for exposure, including those that emit ultraviolet laser light such as KrF excimer lasers (wavelength 248 nm), ArF excimer lasers (wavelength 193 nm), and F2 excimer lasers (wavelength 157 nm); those that emit far-ultraviolet or vacuum-ultraviolet harmonic laser light by wavelength conversion from laser light from solid-state laser sources (such as YAG or semiconductor lasers); and those that irradiate with electron beams or extreme ultraviolet (EUV) light. During exposure, exposure is usually performed through a mask corresponding to the desired pattern, but if the exposure light source is an electron beam, exposure may be performed by direct drawing without using a mask.

[0122] The integrated radiation dose in this process is, for example, 2000 mJ / cm² when using extreme ultraviolet radiation. 2 Preferably, it is 500 mJ / cm². 2 The following is more preferable. Furthermore, when using an electron beam, the cumulative irradiation dose should be 10,000 μC / cm². 2 Preferably, it is 5000 μC / cm². 2 The following is more preferable:

[0123] Furthermore, post-exposure baking (PEB) may be performed after exposure. The lower limit of the PEB temperature is preferably 50°C or higher, and more preferably 80°C or higher. The upper limit of the PEB temperature is preferably 180°C or lower, and more preferably 130°C or lower. The lower limit of the PEB time is preferably 5 seconds or higher, and more preferably 10 seconds or higher. The upper limit of the PEB time is preferably 600 seconds or lower, and more preferably 300 seconds or lower.

[0124] In this invention, in order to maximize the capabilities of the radiation-sensitive resist composition, an organic or inorganic anti-reflective film may be formed on the substrate used, for example. Furthermore, to prevent the influence of basic impurities and other elements in the ambient atmosphere, a protective film may be provided on the coating, for example. Also, when performing immersion exposure, a protective film for immersion exposure may be provided on the resist film, for example, to avoid direct contact between the immersion medium and the resist film.

[0125] <Developing process> In this step, the resist film exposed in the exposure step described above is developed. Examples of developers used for this development include water such as pure water or ultrapure water; alkaline developers; and developers containing organic solvents (hereinafter also referred to as "organic developers"). Examples of development methods include the dip method, paddle method, spray method, and dynamic dispensing method. The development temperature is preferably, for example, 5°C to 60°C, and the development time is preferably, for example, 5 seconds to 300 seconds.

[0126] Examples of alkaline developers include alkaline aqueous solutions 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 (DBU), or 1,5-diazabicyclo-[4.3.0]-5-nonene (DBN). The alkaline developer may also contain a surfactant.

[0127] 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. 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.

[0128] It is preferable to wash the resist pattern with ultrapure water after development, and then remove any remaining water on the substrate and pattern.

[0129] Examples of organic solvents included in the organic developer include those similar to those exemplified in the section [Solvent (B)] above.

[0130] The lower limit of the organic solvent content 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 small amount of water. Furthermore, development may be stopped by substituting the organic developer with a different type of solvent during development.

[0131] It is preferable to wash the resist pattern after development. Ultrapure water, rinsing solution, etc., can be used as the washing solution. There are no particular restrictions on the rinsing solution as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent can be used. Preferred rinsing solutions are alcohol-based solvents or ester-based solvents. After washing, it is preferable to remove any remaining rinsing solution from the substrate and pattern. Also, if ultrapure water is used, it is preferable to remove any remaining water from the substrate and pattern.

[0132] These developing solutions can be used individually or in combination of two or more.

[0133] After forming the resist pattern as described above, a patterned wiring substrate can be obtained by etching. The etching method can be any known method, such as dry etching using plasma gas, or wet etching using an alkaline solution, cupric chloride solution, ferric chloride solution, etc.

[0134] Plating can also be performed after forming the resist pattern. While not particularly limited, the plating method can include copper plating, solder plating, nickel plating, and gold plating.

[0135] The residual resist pattern after etching can be removed with an organic solvent. Examples of such organic solvents are not limited, but include PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), EL (ethyl lactate), etc. The removal method is not limited, but examples include immersion method, spray method, etc. The wiring substrate on which the resist pattern is formed may be a multilayer wiring substrate and may have small diameter through-holes.

[0136] In this embodiment, the wiring substrate can also be formed by a method in which a resist pattern is formed, a metal is deposited in a vacuum, and then the resist pattern is dissolved in a solution, i.e., the lift-off method.

[0137] [Application] The radiation-sensitive resist composition of the present invention is suitable as a resist composition for KrF excimer laser exposure, an ArF excimer laser exposure, an electron beam exposure, or an EUV exposure. More preferably, it is suitable as a resist composition for electron beam exposure or an EUV exposure, and can be used for semiconductor microfabrication.

[0138] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0139] The present invention encompasses the following embodiments and forms.

[0140] [1] An ionic salt (A) containing an anion (a) and an organic cation (b) having a metal chalcogenide cluster structure, Solvent (B) and, A radiation-resistant composition comprising, The anion (a) comprises at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. The organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms. A radiation-sensitive resist composition wherein the content of the ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 20% by mass or more and 100% by mass or less.

[0141] [2] The radiation-sensitive resist composition according to [1], wherein the anion (a) is at least one selected from the group consisting of anions represented by the following chemical formulas (a-1) to (a-6):

[0142] [ka]

[0143] In the above general formula (a-1), M 1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m1 is an integer between 4 and 60, and multiple M 1 They may be the same or they may be different. X 1 is at least one selected from the group consisting of O, OH, S, and Se, n1 is an integer between 10 and 200, and multiple X 1 They may be the same or they may be different. q1 is an integer between 2 and 40 (inclusive):

[0144] [ka]

[0145] In the above general formula (a-2), M 2-1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m2-1 is an integer between 4 and 60, and multiple M 2-1 They may be the same or they may be different. M 2-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m2-2 is an integer between 1 and 10, and if m2-2 is 2 or greater, multiple M 2-2 They may be the same or they may be different. X 2 is at least one selected from the group consisting of O, OH, S, and Se, n2 is an integer between 10 and 200, and multiple X 2 They may be the same or they may be different. q2 is an integer between 2 and 40 (inclusive):

[0146] [ka]

[0147] In the above general formula (a-3), M 3 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m3 is an integer between 4 and 60, and multiple M 3 They may be the same or they may be different. X 3 is at least one selected from the group consisting of O, OH, S, and Se, n3 is an integer between 10 and 200, and multiple X3 They may be the same or they may be different. R 1 This is an organic group having 1 to 20 carbon atoms. r1 is an integer between 1 and 10, and if r1 is 2 or greater, multiple R 1 They may be the same or they may be different. q3 is an integer between 2 and 40 (inclusive):

[0148] [ka]

[0149] In the above general formula (a-4), M 4-1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m4-1 is an integer between 4 and 60, and multiple M 4-1 They may be the same or they may be different. M 4-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m4-2 is an integer between 1 and 10, and if m4-2 is 2 or greater, multiple M 4-2 They may be the same or they may be different. X 4 is at least one selected from the group consisting of O, OH, S, and Se, n4 is an integer between 10 and 200, and multiple X 4 They may be the same or they may be different. R 2 This is an organic group having 1 to 20 carbon atoms. r2 is an integer between 1 and 10, and if r2 is 2 or greater, multiple R 2 They may be the same or they may be different. q4 is an integer between 2 and 40 (inclusive):

[0150] [ka]

[0151] In the above general formula (a-5), M 5-1 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m5-1 is an integer between 4 and 60, and multiple M 5-1 They may be the same or they may be different. M 5-2 is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m5-2 is an integer between 1 and 10, and if m5-2 is 2 or greater, multiple M 5-2 They may be the same or they may be different. X 5 is at least one selected from the group consisting of O, OH, S, and Se, n5 is an integer between 10 and 200, and multiple X 5 They may be the same or they may be different. h is an integer between 1 and 10, R 3 This is an organic group having 1 to 20 carbon atoms. r3 is an integer between 1 and 10, and if r3 is 2 or greater, multiple R 3 They may be the same or they may be different. q5 is an integer between 2 and 40 (inclusive):

[0152] [ka]

[0153] In the above general formula (a-6), M 6 is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m6 is an integer between 4 and 60, and multiple M 6 They may be the same or they may be different. X 6 is at least one selected from the group consisting of O, OH, S, and Se, n6 is an integer between 10 and 200, and multiple X 6 They may be the same or they may be different. Z is an inorganic functional group comprising at least one atom selected from the group consisting of nitrogen, phosphorus, and sulfur atoms, and an oxygen atom. p is an integer between 1 and 10, and if p is 2 or greater, multiple Zs may be the same or different from each other. q6 is an integer between 2 and 40 (inclusive).

[0154] [3] The radiation-sensitive resist composition according to [1] or [2], wherein the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms.

[0155] [4] The radiation-sensitive resist composition according to any one of [1] to [3], wherein the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms.

[0156] [5] The radiation-sensitive resist composition according to any one of [1] to [4], wherein the molecular weight of the anion (a) is 600 or more and 9000 or less.

[0157] [6] The radiation-sensitive resist composition according to any one of [1] to [5], wherein the average diameter of the anion (a) is 0.5 nm or more and 10 nm or less.

[0158] [7] The radiation-sensitive resist composition according to any one of [2] to [6], wherein q1 in general formula (a-1), q2 in general formula (a-2), q3 in general formula (a-3), q4 in general formula (a-4), q5 in general formula (a-5), and q6 in general formula (a-6) are each independently integers between 3 and 15.

[0159] [8] The radiation-sensitive resist composition according to any one of [1] to [7], wherein the molecular weight of the organic cation (b) is 50 or more and 5000 or less.

[0160] [9] The radiation-sensitive resist composition according to any one of [1] to [8], wherein the total molecular weight of the ionic salt (A) is 650 or more and 30,000 or less.

[0161]

[10] The radiation-sensitive resist composition according to any one of [1] to [9], wherein the ratio of the molecular weight of the anion (a) to the total molecular weight of the organic cation (b) [molecular weight of (a) / total molecular weight of (b)] is 0.3 or more and 30 or less.

[0162]

[11] A positive-type radiation-sensitive resist composition according to any of [1] to

[10] . [Examples]

[0163] 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 methods described below.

[0164] [Analysis method] (Fourier transform infrared spectroscopy (FT-IR) measurement) Fourier transform infrared spectrophotometers (Thermo Scientific, Nicolet iS10) were used to measure the Fourier transform infrared spectral spectrum using the ATR method.

[0165] (Measurement of elemental content of V, Nb, Ta, Mo, and W (elemental analysis)) Using an ICP emission spectrometer (EMAXEvolution, manufactured by Horiba, Ltd.), the total content (in mass%) of the five elements V, Nb, Ta, Mo, and W relative to the total mass of the ionic salt was determined.

[0166] (Synthesis Example 1) <Compound 1:[PMo 12 O 40 ] 3- • Synthesis of 3 {tris[2-(2-methoxyethoxy)ethyl]ammonium} Compound 1 was synthesized according to the synthesis method described in Angew. Chem. Int. Ed. 2017, 56, 2974-2978. Specifically, 0.797 g (2.47 mmol) of tris[2-(2-methoxyethoxy)ethyl]amine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were placed in a 100 ml round-bottom flask, and then 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride. In another 200 ml round-bottom flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were placed, and then the aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride obtained above was added dropwise. After dropwise addition, the mixture was stirred at room temperature, and the supernatant was removed by centrifugation. 27.4 g of pure water was added, and the centrifugation process to remove the supernatant was repeated twice. The resulting solid was then vacuum-dried to obtain 1.51 g of compound 1 as a yellow solid.

[0167] The FT-IR spectrum of compound 1 obtained is shown in Figure 1.

[0168] (Synthesis Example 2) <Compound 2: [SiW 12 O 40 ] 4- Synthesis of 4 (triphenylsulfonium) 0.700 g (0.236 mmol) of sodium 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 17.5 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 100 ml round-bottom flask and stirred at room temperature. Next, 0.648 g (1.89 mmol) of triphenylsulfonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at room temperature. Furthermore, 37.1 g of pure water was added and stirred at room temperature, after which the solid was filtered off. The obtained solid was washed with pure water and vacuum-dried to obtain 0.861 g of compound 2 as a white solid.

[0169] The FT-IR spectrum of the obtained compound 2 is shown in Figure 2.

[0170] (Synthesis Example 3) <Compound 3:[PMo 12 O 40 ] 3- Synthesis of 3 (diphenyliodonium) In a 30 ml round-bottom flask, 0.416 g (1.32 mmol) of diphenyliodonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 10.6 g of pure water, and 7.92 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of diphenyliodonium chloride. In another 100 ml round-bottom flask, 0.400 g (0.219 mmol) of 12-molybd(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 10.6 g of pure water were added and stirred at room temperature. The aqueous solution of diphenyliodonium chloride obtained above was added dropwise and stirred at room temperature. After adding 21.2 g of pure water and stirring at room temperature, the solid was filtered off. The filtered solid was washed with pure water and vacuum-dried to obtain 0.436 g of compound 3, a yellow solid.

[0171] The FT-IR spectrum of the obtained compound 3 is shown in Figure 3.

[0172] (Synthesis Example 4) <Compound 4:[PW 12 O 40 ] 3- Synthesis of 3 (triphenylsulfonium) In a 30 ml round-bottom flask, 0.358 g (1.04 mmol) of triphenylsulfonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 13.3 g of pure water were added and stirred at room temperature to obtain an aqueous solution of triphenylsulfonium bromide. In another 100 ml round-bottom flask, 0.500 g (0.174 mmol) of dodecatungst(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 13.3 g of pure water were added and stirred at room temperature. The aqueous solution of triphenylsulfonium bromide obtained above was added dropwise and stirred at room temperature. After adding 26.5 g of pure water and stirring at room temperature, the solid was filtered off. The filtered solid was washed with pure water and vacuum-dried to obtain 0.532 g of compound 4 as a white solid.

[0173] The FT-IR spectrum of the obtained compound 4 is shown in Figure 4.

[0174] (Synthesis Example 5) <Compound 5:[PMo 12 O 40 ] 3- Synthesis of 3 (triphenylsulfonium) In a 30 ml round-bottom flask, 0.451 g (1.32 mmol) of triphenylsulfonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 10.6 g of pure water were added and stirred at room temperature to obtain an aqueous solution of triphenylsulfonium bromide. In another 100 ml round-bottom flask, 0.400 g (0.219 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 10.6 g of pure water were added and stirred at room temperature. The aqueous solution of triphenylsulfonium bromide obtained above was added dropwise and stirred at room temperature. After adding 21.2 g of pure water and stirring at room temperature, the solid was filtered off. The filtered solid was washed with pure water and vacuum-dried to obtain 0.435 g of compound 5, a yellow solid.

[0175] The FT-IR spectrum of the obtained compound 5 is shown in Figure 5.

[0176] (Synthesis Example 6) <Compound 6:[PW 12 O 40 ] 3- Synthesis of 3 (diphenyliodonium) In a 30 ml round-bottom flask, 0.330 g (1.04 mmol) of diphenyliodonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 13.3 g of pure water, and 6.73 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of diphenyliodonium chloride. In another 100 ml round-bottom flask, 0.500 g (0.174 mmol) of dodecatungst(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 13.3 g of pure water were added and stirred at room temperature. The aqueous solution of diphenyliodonium chloride obtained above was added dropwise and stirred at room temperature. After adding 26.5 g of pure water and stirring at room temperature, the solid was filtered off. The filtered solid was washed with pure water and vacuum-dried to obtain 0.526 g of compound 6, a white solid.

[0177] The FT-IR spectrum of the obtained compound 6 is shown in Figure 6.

[0178] (Synthesis Example 7) <Compound 7:[SiW 12 O 40 ] 4- Synthesis of 4 (diphenyliodonium) In a 30 ml round-bottom flask, 0.191 g (0.604 mmol) of diphenyliodonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 13.3 g of pure water, and 5.94 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of diphenyliodonium chloride. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 13.3 g of pure water were added and stirred at room temperature. The aqueous solution of diphenyliodonium chloride obtained above was added dropwise and stirred at room temperature. After adding 26.5 g of pure water and stirring at room temperature, the solid was filtered off. The filtered solid was washed with pure water and vacuum-dried to obtain 0.543 g of compound 7, a white solid.

[0179] The FT-IR spectrum of the obtained compound 7 is shown in Figure 7.

[0180] (Synthesis Example 8) <Compound 8:[PW 12 O 40 ] 3- Synthesis of 2{tris[2-(2-methoxyethoxy)ethyl]ammonium}H> Compound 8 was synthesized according to the synthesis method described in Angew. Chem. Int. Ed. 2017, 56, 2974-2978. Specifically, 0.112 g (0.347 mmol) of tris[2-(2-methoxyethoxy)ethyl]amine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 22.8 g of pure water were placed in a 30 ml round-bottom flask, and then 6 N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride. In another 100 ml round-bottom flask, 1.00 g (0.347 mmol) of 12-tungst(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 23.1 g of pure water were placed, and then the aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation process was repeated twice. The resulting solid was then vacuum-dried to obtain 0.619 g of compound 8 as a white solid.

[0181] The FT-IR spectrum of the obtained compound 8 is shown in Figure 8.

[0182] (Synthesis Example 9) <Compound 9:[PMo 12 O 40 ] 3- Synthesis of 2{tris[2-(2-methoxyethoxy)ethyl]ammonium}H> Compound 9 was synthesized according to the synthesis method described in Angew. Chem. Int. Ed. 2017, 56, 2974-2978. Specifically, 0.160 g (0.493 mmol) of tris[2-(2-methoxyethoxy)ethyl]amine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 32.4 g of pure water were placed in a 50 ml round-bottom flask, and then 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride. In another 100 ml round-bottom flask, 0.900 g (0.493 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 32.9 g of pure water were placed, and then the aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 16.4 g of pure water was added, and the centrifugation process was repeated twice. The resulting solid was then vacuum-dried to obtain 0.562 g of compound 9 as a white solid.

[0183] The FT-IR spectrum of the obtained compound 9 is shown in Figure 9.

[0184] (Synthesis Example 10) <Compound 10: [SiW 12 O 40 ] 4- • Synthesis of 4[bis(4-tert-butylphenyl)iodonium] > In a 30 ml round-bottom flask, 0.518 g (1.21 mmol) of bis(4-tert-butylphenyl)iodonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of bis(4-tert-butylphenyl)iodonium chloride. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of bis(4-tert-butylphenyl)iodonium chloride obtained above was added dropwise and stirred at room temperature. Further addition of 6.50 g of pure water and 6.50 g of methanol was added and stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and then vacuum-dried to obtain 0.583 g of compound 10 as a white solid.

[0185] The FT-IR spectrum of the obtained compound 10 is shown in Figure 10.

[0186] (Synthesis Example 11) <Compound 11:[SiW 12 O 40 ] 4- • Synthesis of 4[(4-nitrophenyl)(phenyl)iodonium] > In a 30 ml round-bottom flask, 0.574 g (1.21 mmol) of (4-nitrophenyl)(phenyl)iodonium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of (4-nitrophenyl)(phenyl)iodonium trifluoromethanesulfonate. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of (4-nitrophenyl)(phenyl)iodonium trifluoromethanesulfonate obtained above was added dropwise and stirred at room temperature. Further addition of 6.50 g of pure water and 6.50 g of methanol was added and stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and vacuum-dried to obtain 0.658 g of compound 11 as a white solid.

[0187] The FT-IR spectrum of the obtained compound 11 is shown in Figure 11.

[0188] (Synthesis Example 12) <Compound 12:[SiW 12 O 40 ] 4- • Synthesis of 4[(4-methylphenyl)(2,4,6-trimethylphenyl)iodonium] In a 30 ml round-bottom flask, 0.588 g (1.21 mmol) of (4-methylphenyl)(2,4,6-trimethylphenyl)iodonium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of (4-methylphenyl)(2,4,6-trimethylphenyl)iodonium trifluoromethanesulfonate. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of (4-methylphenyl)(2,4,6-trimethylphenyl)iodonium trifluoromethanesulfonate obtained above was added dropwise to this solution and stirred at room temperature. Further, 6.50 g of pure water and 6.50 g of methanol were added and the mixture was stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and vacuum-dried to obtain 0.623 g of compound 12 as a white solid.

[0189] The FT-IR spectrum of the obtained compound 12 is shown in Figure 12.

[0190] (Synthesis Example 13) <Compound 13:[SiW 12 O 40 ] 4- • Synthesis of 4{phenyl[3-(trifluoromethyl)phenyl]iodonium} In a 30 ml round-bottom flask, 0.602 g (1.21 mmol) of phenyl[3-(trifluoromethyl)phenyl]iodonium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of phenyl[3-(trifluoromethyl)phenyl]iodonium trifluoromethanesulfonate. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of phenyl[3-(trifluoromethyl)phenyl]iodonium trifluoromethanesulfonate obtained above was added dropwise to this solution and stirred at room temperature. Further, 6.50 g of pure water and 6.50 g of methanol were added and the mixture was stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and vacuum-dried to obtain 0.618 g of compound 13 as a white solid.

[0191] The FT-IR spectrum of the obtained compound 13 is shown in Figure 13.

[0192] (Synthesis Example 14) <Compound 14:[SiW 12 O 40 ] 4- • Synthesis of 4 [phenyl(2,4,6-trimethoxyphenyl)iodonium] In a 30 ml round-bottom flask, 0.655 g (1.21 mmol) of phenyl(2,4,6-trimethoxyphenyl)iodonium tosylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of phenyl(2,4,6-trimethoxyphenyl)iodonium tosylate. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of phenyl(2,4,6-trimethoxyphenyl)iodonium tosylate obtained above was added dropwise and stirred at room temperature. Further addition of 6.50 g of pure water and 6.50 g of methanol was added and stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and vacuum-dried to obtain 0.645 g of compound 14 as a white solid.

[0193] The FT-IR spectrum of the obtained compound 14 is shown in Figure 14.

[0194] (Synthesis Example 15) <Compound 15:[SiW 12 O 40 ] 4- • Synthesis of 4{[3-(trifluoromethyl)phenyl](2,4,6-trimethylphenyl)iodonium} In a 30 ml round-bottom flask, 0.653 g (1.21 mmol) of [3-(trifluoromethyl)phenyl](2,4,6-trimethylphenyl)iodonium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.50 g of pure water, and 6.50 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain an aqueous solution of phenyl(2,4,6-trimethoxyphenyl)iodonium trifluoromethanesulfonate. In another 100 ml round-bottom flask, 0.500 g (0.151 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 6.50 g of pure water, and 6.50 g of methanol were added and stirred at room temperature. The aqueous solution of phenyl(2,4,6-trimethoxyphenyl)iodonium trifluoromethanesulfonate obtained above was added dropwise to this solution and stirred at room temperature. Further, 6.50 g of pure water and 6.50 g of methanol were added and the mixture was stirred at room temperature, after which the solid was filtered off. The filtered solid was washed with a 1:1 (mass ratio) mixture of pure water and methanol, and vacuum-dried to obtain 0.658 g of compound 15 as a white solid.

[0195] The FT-IR spectrum of the obtained compound 15 is shown in Figure 15.

[0196] (Synthesis Example 16) <Compound 16:[PMo 12 O 40 ] 3- Synthesis of 3 (triheptylammonium) Compound 16 was synthesized according to the synthesis method described in Angew. Chem. Int. Ed. 2017, 56, 2974-2978. Specifically, 2.00 g (1.10 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 73.0 g of pure water were placed in a 100 ml round-bottom flask and stirred at room temperature to obtain an aqueous solution of 12-molybdo(VI) phosphate n-hydrate. In another 300 ml round-bottom flask, 0.341 g (1.10 mmol) of triheptylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 68.3 g of pure water, and 2.88 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed, and then 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5. Next, an aqueous solution of the 12-molybdo(VI) phosphate n-hydrate obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 36.5 g of pure water was added, and the process of removing the supernatant by centrifugation was repeated twice. The resulting solid was then vacuum-dried to obtain 0.820 g of compound 16, a yellow solid.

[0197] The FT-IR spectrum of the obtained compound 16 is shown in Figure 16.

[0198] (Synthesis Example 17) <Compound 17:[PMo 12 O 40 ] 3- Synthesis of 3 (triethylammonium) In a 50 ml eggplant-shaped flask, 0.499 g (0.493 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 32.4 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of triethylamine hydrochloride. In another 100 ml eggplant-shaped flask, 0.900 g (0.493 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 32.9 g of pure water were added. The above-prepared aqueous solution of triethylamine hydrochloride was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Further, 16.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was then vacuum-dried to obtain 0.261 g of compound 17, a yellow solid.

[0199] The FT-IR spectrum of the obtained compound 17 is shown in Figure 17.

[0200] (Synthesis Example 18) <Compound 18:[PMo 12 O 40 ] 3- Synthesis of 3 (pyridinium) In a 100 ml eggplant-shaped flask, 0.0770 g (0.822 mmol) of pyridine hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous pyridine hydrochloride solution. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous pyridine hydrochloride solution obtained above was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.307 g of compound 18, a yellow solid.

[0201] The FT-IR spectrum of the obtained compound 18 is shown in Figure 18.

[0202] (Synthesis Example 19) <Compound 19:[PMo 12 O 40 ] 3- • Synthesis of 3(N,N,N',N',-tetramethylethylenediammonium) In a 100 ml eggplant-shaped flask, 0.0955 g (0.822 mmol) of N,N,N',N',-tetramethylethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of N,N,N',N',-tetramethylethylenediamine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of N,N,N',N',-tetramethylethylenediamine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.750 g of compound 19, a yellow solid.

[0203] The FT-IR spectrum of the obtained compound 19 is shown in Figure 19.

[0204] (Synthesis Example 20) <Compound 20:[PMo 12 O 40 ] 3- Synthesis of 3 (triethanolammonium) In a 100 ml eggplant-shaped flask, 0.153 g (0.822 mmol) of triethanolamine hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous triethanolamine hydrochloride solution. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The above-prepared aqueous triethanolamine hydrochloride solution was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.230 g of compound 20, a yellow solid.

[0205] The FT-IR spectrum of the obtained compound 20 is shown in Figure 20.

[0206] (Synthesis Example 21) <Compound 21:[PMo 12 O 40 ] 3- Synthesis of 3(N,N-dimethylanilinium) In a 100 ml eggplant-shaped flask, 0.100 g (0.822 mmol) of N,N-dimethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of N,N-dimethylaniline hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The above-prepared aqueous solution of N,N-dimethylaniline hydrochloride was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.534 g of compound 21, a yellow solid.

[0207] The FT-IR spectrum of the obtained compound 21 is shown in Figure 21.

[0208] (Synthesis Example 22) <Compound 22:[PW 12 O 40 ] 3- • Synthesis of 3(1,1-diphenylhydrazinium) In a 100 ml eggplant-shaped flask, 0.115 g (0.521 mmol) of 1,1-diphenylhydrazine hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 34.2 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of 1,1-diphenylhydrazine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.521 mmol) of 12-tungst(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 34.7 g of pure water were added. The aqueous solution of 1,1-diphenylhydrazine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 8.68 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.405 g of compound 22 as a white solid.

[0209] The FT-IR spectrum of the obtained compound 22 is shown in Figure 22.

[0210] (Synthesis Example 23) <Compound 23:[PW 12 O 40 ] 3- Synthesis of 3(N,N-dimethylanilinium) In a 100 ml eggplant-shaped flask, 0.631 g (0.521 mmol) of N,N-dimethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) and 34.2 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of N,N-dimethylaniline hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.521 mmol) of 12-tungst(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 34.7 g of pure water were added. The above-prepared aqueous solution of N,N-dimethylaniline hydrochloride was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Further, 17.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was then vacuum-dried to obtain 0.536 g of compound 23 as a white solid.

[0211] The FT-IR spectrum of the obtained compound 23 is shown in Figure 23.

[0212] (Synthesis Example 24) <Compound 24:[SiW 12 O 40 ] 4- Synthesis of 4(N,N-dimethylanilinium) In a 100 ml eggplant-shaped flask, 0.110 g (0.906 mmol) of N,N-dimethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) and 29.8 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of N,N-dimethylaniline hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.453 mmol) of 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 30.2 g of pure water were added. The above-prepared aqueous solution of N,N-dimethylaniline hydrochloride was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Further, 15.1 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was then vacuum-dried to obtain 0.709 g of compound 24 as a white solid.

[0213] The FT-IR spectra of the obtained compound 24 are shown in Figure 24.

[0214] (Synthesis Example 25) <Compound 25:[PMo 12 O 40 ] 3- • Synthesis of 3(1-methylpyridinium) In a 100 ml eggplant-shaped flask, 0.106 g (0.822 mmol) of 1-methylpyridine hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of 1-methylpyridine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 1-methylpyridine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the process of removing the supernatant by centrifugation was repeated twice. The resulting solid was vacuum-dried to obtain 0.510 g of compound 25, a yellow solid.

[0215] The FT-IR spectrum of the obtained compound 25 is shown in Figure 25.

[0216] (Synthesis Example 26) <Compound 26:[PMo 12 O 40 ] 3- • Synthesis of 3 (Imidazolium) > 0.0859 g (0.822 mmol) of imidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were placed in a 100 ml eggplant-shaped flask. Then, a 6 N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an imidazole hydrochloride aqueous solution. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were placed. The imidazole hydrochloride aqueous solution obtained above was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Further, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was then vacuum-dried to obtain 0.325 g of compound 26, a yellow solid.

[0217] The FT-IR spectrum of the obtained compound 26 is shown in Figure 26.

[0218] (Synthesis Example 27) <Compound 27:[PMo 12 O 40 ] 3- Synthesis of 3(1,3-dimethylimidazolium) In a 100 ml eggplant-shaped flask, 0.109 g (0.822 mmol) of 1,3-dimethylimidazole hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of 1,3-dimethylimidazole hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 1,3-dimethylimidazole hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.423 g of compound 27, a yellow solid.

[0219] The FT-IR spectrum of the obtained compound 27 is shown in Figure 27.

[0220] (Synthesis Example 28) <Compound 28:[PMo 12 O 40 ] 3- • Synthesis of 3(N,N,2,4,6-pentamethylanilinium) In a 100 ml eggplant-shaped flask, 0.134 g (0.822 mmol) of N,N,2,4,6-pentamethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, 6N hydrochloric acid solution was added to adjust the pH to 1.5, obtaining an aqueous solution of N,N,2,4,6-pentamethylaniline hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of N,N,2,4,6-pentamethylaniline hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.475 g of compound 28, a yellow solid.

[0221] The FT-IR spectrum of the obtained compound 28 is shown in Figure 28.

[0222] (Synthesis Example 29) <Compound 29:[PMo 12 O 40 ] 3- Synthesis of 3(1,3-di-o-trilguanidinium) In a 100 ml eggplant-shaped flask, 0.197 g (0.822 mmol) of 1,3-di-o-tolylguanidine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of 1,3-di-o-tolylguanidine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 1,3-di-o-tolylguanidine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.451 g of compound 29, a yellow solid.

[0223] The FT-IR spectrum of the obtained compound 29 is shown in Figure 29.

[0224] (Synthesis Example 30) <Compound 30:[PMo 12 O 40 ] 3- • Synthesis of 3(1-phenylpiperidinium) In a 100 ml eggplant-shaped flask, 0.132 g (0.822 mmol) of 1-phenylpiperidine (manufactured by Tokyo Chemical Industry Co., Ltd.), 54.0 g of pure water, and 10.8 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of 1-phenylpiperidine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 1-phenylpiperidine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 13.7 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 1.19 g of compound 30, a yellow solid.

[0225] The FT-IR spectrum of the obtained compound 30 is shown in Figure 30.

[0226] (Synthesis Example 31) <Compound 31:[PMo 12 O 40 ] 3- Synthesis of 3 (triethylenediammonium) In a 100 ml eggplant-shaped flask, 0.0992 g (0.822 mmol) of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of triethylenediamine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The above-prepared aqueous solution of triethylenediamine hydrochloride was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 13.7 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 1.07 g of compound 31, a yellow solid.

[0227] The FT-IR spectrum of the obtained compound 31 is shown in Figure 31.

[0228] (Synthesis Example 32) <Compound 32:[PMo 12 O 40 ] 3- • Synthesis of 3(1,1,3,3-tetramethylguanidinium) In a 100 ml eggplant-shaped flask, 0.0946 g (0.822 mmol) of 1,1,3,3-tetramethylguanidine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, 6N hydrochloric acid solution was added to adjust the pH to 1.5, obtaining an aqueous solution of 1,1,3,3-tetramethylguanidine hydrochloride. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 1,1,3,3-tetramethylguanidine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.466 g of compound 32, a yellow solid.

[0229] The FT-IR spectrum of the obtained compound 32 is shown in Figure 32.

[0230] (Synthesis Example 33) <Compound 33:[PMo 12 O 40 ] 3- • Synthesis of 3 (methyltriphenylphosphonium) In a 100 ml eggplant-shaped flask, 0.294 g (0.822 mmol) of methyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5 to obtain an aqueous solution of methyltriphenylphosphonium bromide. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybd(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of methyltriphenylphosphonium bromide obtained above was added dropwise to this solution. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 13.7 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.520 g of compound 33, a yellow solid.

[0231] The FT-IR spectrum of the obtained compound 33 is shown in Figure 33.

[0232] (Synthesis Example 34) <Compound 34:[PMo 12 O 40 ] 3- Synthesis of 3 (tetraphenylphosphonium) In a 100 ml eggplant-shaped flask, 0.345 g (0.822 mmol) of tetraphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of tetraphenylphosphonium bromide. In another 200 ml eggplant-shaped flask, 1.50 g (0.822 mmol) of 12-molybd(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of tetraphenylphosphonium bromide obtained above was then added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 13.7 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.570 g of compound 34, a yellow solid.

[0233] The FT-IR spectrum of the obtained compound 34 is shown in Figure 34.

[0234] (Synthesis Example 35) <Compound 35:[Mo6O 19 ] 2- Synthesis of 2 (diphenyliodonium) In a 100 ml round-bottom flask, 2.70 g (7.328 mmol) of diphenyliodonium tetrafluoroborate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 24.4 g of acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature to obtain a diphenyliodonium tetrafluoroborate solution. In another 200 ml round-bottom flask, [Mo6O 19 ][(C 16 H 36 0.500 g (0.366 mmol) of [N)2] and 24.4 g of acetonitrile were added, and the diphenyliodonium tetrafluoroborate solution obtained above was added dropwise. After stirring at room temperature, 48.1 g of pure water was added, and the mixture was stirred again at room temperature, and the supernatant was removed by centrifugation. Further, 12.2 g of pure water was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.484 g of compound 35 as a yellow solid.

[0235] The FT-IR spectrum of the obtained compound 35 is shown in Figure 35.

[0236] (Synthesis Example 36) <Compound 36:[PMo 12 O 40 ] 3- • Synthesis of 3(4-methoxybenzenediazonium) In a 100 ml round-bottom flask, 0.182 g (0.822 mmol) of 4-methoxyazobenzenediazonium tetrafluoroborate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 54.0 g of pure water were added. Then, a 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.5, obtaining an aqueous solution of 4-methoxyazobenzenediazonium tetrafluoroborate. In another 200 ml round-bottom flask, 1.50 g (0.822 mmol) of 12-molybdo(VI) phosphate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 54.8 g of pure water were added. The aqueous solution of 4-methoxyazobenzenediazonium tetrafluoroborate obtained above was added dropwise. The mixture was stirred at room temperature, and the supernatant was removed by centrifugation. Furthermore, 27.4 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.558 g of compound 36, a yellow solid.

[0237] The FT-IR spectra of the obtained compound 36 are shown in Figure 36.

[0238] (Synthesis Example 37) <Compound 37:[W 10 O 32 ] 4- • Synthesis of 4 {tris[2-(2-methoxyethoxy)ethyl]ammonium} In a 10 ml round-bottom flask, 0.132 g (0.409 mmol) of tris[2-(2-methoxyethoxy)ethyl]amine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.41 g of pure water were added. Then, 6 N hydrochloric acid solution was added to adjust the pH to 1.0, obtaining an aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride. In another 50 ml round-bottom flask, 0.250 g (0.102 mmol) of sodium decatungstate (manufactured by Aldrich) and 3.41 g of pure water were added. The aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, 13.4 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. Furthermore, 3.41 g of ethanol was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.101 g of compound 37 as a white solid.

[0239] The FT-IR spectrum of the obtained compound 37 is shown in Figure 37.

[0240] (Synthesis Example 38) <Compound 38:[W 10 O 32 ] 4- Synthesis of 4 (diphenyliodonium) In a 10 ml round-bottom flask, 0.151 g (0.409 mmol) of diphenyliodonium tetrafluoroborate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 6.82 g of acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added. Then, 6N hydrochloric acid aqueous solution was added to adjust the pH to 1.0, obtaining a diphenyliodonium tetrafluoroborate solution. In another 200 ml round-bottom flask, 0.250 g (0.102 mmol) of sodium decatungstate (manufactured by Aldrich), 36.9 g of acetonitrile, and 120 g of pure water were added. The diphenyliodonium tetrafluoroborate solution obtained above was then added dropwise. The mixture was stirred at room temperature, 13.4 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. Furthermore, 3.41 g of pure water was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.178 g of compound 38 as a white solid.

[0241] The FT-IR spectrum of the obtained compound 38 is shown in Figure 38.

[0242] (Synthesis Example 39) <Compound 39:[Mo7O 24 ] 6- • Synthesis of 6 {tris[2-(2-methoxyethoxy)ethyl]ammonium} In a 100 ml round-bottom flask, 1.67 g (5.12 mmol) of tris[2-(2-methoxyethoxy)ethyl]amine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 23.5 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added. Then, a 1 N hydrochloric acid aqueous solution was added to adjust the pH to 6.0, obtaining an aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride. In another 200 ml round-bottom flask, 0.500 g (0.430 mmol) of ammonium molybdate(VI) tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 28.6 g of pure water were added. The aqueous solution of tris[2-(2-methoxyethoxy)ethyl]amine hydrochloride obtained above was added dropwise. The mixture was stirred at room temperature, 23.5 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. Furthermore, 23.5 g of ethanol was added, and the supernatant was removed by centrifugation. This process was repeated twice, and the resulting solid was vacuum-dried to obtain 0.534 g of compound 39, a yellow solid.

[0243] The FT-IR spectrum of the obtained compound 39 is shown in Figure 39.

[0244] (Synthesis Example 40) <Compound 40:[Mo7O 24 ] 6- Synthesis of 6 (diphenyliodonium) In a 50 ml round-bottom flask, 0.948 g (2.58 mmol) of diphenyliodonium tetrafluoroborate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 14.3 g of acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed to obtain a diphenyliodonium tetrafluoroborate solution. In another 200 ml round-bottom flask, 0.250 g (0.215 mmol) of ammonium molybdenate(VI) tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 44.3 g of acetonitrile, and 40.0 g of pure water were placed, and the diphenyliodonium tetrafluoroborate solution obtained above was added dropwise. The mixture was stirred at room temperature, 28.2 g of pure water was added, and the mixture was stirred again at room temperature. The supernatant was removed by centrifugation. Further, 7.16 g of pure water was added, and the centrifugation and removal of the supernatant was repeated twice. The resulting solid was vacuum-dried to obtain 0.258 g of compound 40, a yellow solid.

[0245] The FT-IR spectrum of the obtained compound 40 is shown in Figure 40.

[0246] (Synthesis example A) (Synthesis of N-benzyl-2-[(4-iodobenzoyl)oxy]-N,N-dimethylethane-1-aminium bromide) In a 100 ml round-bottom flask, 1.34 g (15.0 mmol) of 2-(dimethylamino)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and methylene chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred under ice cooling. Next, 1.52 g (15.0 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 4.00 g (15.0 mmol) of 4-iodobenzoyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and stirred at room temperature. 17.7 g of saturated sodium bicarbonate aqueous solution was added dropwise, and the organic layer was obtained by liquid-liquid extraction. After dehydration with sodium sulfate, the organic layer was filtered to obtain the organic layer. After removing methylene chloride using an evaporator, the mixture was purified by silica gel column chromatography to obtain 3.49 g of orange solid 2-(dimethylamino)ethyl-4-iodobenzoate.

[0247] 2.39 g (7.50 mmol) of the 2-(dimethylamino)ethyl-4-iodobenzoate obtained above and 25.7 g of acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 50 ml round-bottom flask and stirred at room temperature. Next, 1.28 g (7.50 mmol) of benzyl bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at room temperature. The precipitated solid was filtered, washed with acetonitrile, and then vacuum-dried to obtain 3.20 g of N-benzyl-2-[(4-iodobenzoyl)oxy]-N,N-dimethylethane-1-aminium bromide as a white solid.

[0248] (Synthesis Example 41) <Compound 41:[SiW 12 O 40 ] 4- Synthesis of 4[2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium] In a 100 ml round-bottom flask, 0.523 g (0.150 mmol) of sodium 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 13.1 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed and stirred at room temperature. To this, a solution of 0.432 g (1.20 mmol) of 2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), dissolved in 13.1 g of dimethyl sulfoxide, was added dropwise. The mixture was stirred at room temperature, 26.2 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 13.1 g of pure water and removing the supernatant by centrifugation was repeated twice. Furthermore, 13.1 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.449 g of compound 41 as a white solid.

[0249] The FT-IR spectrum of the obtained compound 41 is shown in Figure 41.

[0250] (Synthesis Example 42) <Compound 42:[W6O 19 ] 2-Synthesis of 1,4(tetrabutylammonium)0.6[2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium] In a 100ml eggplant-shaped flask, add [W6O 19 0.473 g (0.250 mmol) of [(tetrabutylammonium)2] and 11.8 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. A solution of 0.360 g (1.00 mmol) of 2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 11.8 g of dimethyl sulfoxide was added dropwise. The mixture was stirred at room temperature, 23.7 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 11.8 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 11.8 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.387 g of compound 42 as a white solid.

[0251] The FT-IR spectrum of the obtained compound 42 is shown in Figure 42.

[0252] (Synthesis Example 43) <Compound 43:[Mo6O 19 ] 2- Synthesis of 1,2(tetrabutylammonium)0.8[2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium] [Mo6O 190.409 g (0.300 mmol) of [(tetrabutylammonium)2] and 10.2 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. A solution of 0.432 g (1.20 mmol) of 2-(acryloyloxy)-N-benzyl-N,N-dimethylethane-1-aminium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 10.2 g of dimethyl sulfoxide was added dropwise. The mixture was stirred at room temperature, 20.4 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 10.2 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 10.2 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.347 g of compound 43, a yellow solid.

[0253] The FT-IR spectrum of the obtained compound 43 is shown in Figure 43.

[0254] (Synthesis example B) <Synthesis of 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide> In a 100 ml round-bottom flask, 5.00 g (30.7 mmol) of 4-azidocarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 17.9 g of methylene chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. Next, 2.73 g (30.7 mmol) of 2-(dimethylamino)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.374 g (3.07 mmol) of dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 7.05 g (36.8 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and stirred at room temperature. Furthermore, 17.9 g of methylene chloride and 17.9 g of pure water were added, and the mixture was separated to obtain an organic layer. The organic layer was washed with saturated saline solution, dehydrated with sodium sulfate, and filtered to obtain the organic layer. After removing methylene chloride using an evaporator and purifying by silica gel column chromatography, 4.05 g of colorless oily 2-(dimethylamino)ethyl-4-azidobenzoate was obtained.

[0255] In a 50 ml round-bottom flask, 1.17 g (5.00 mmol) of the 2-(dimethylamino)ethyl-4-azidobenzoate obtained above and 17.1 g of acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed and stirred at room temperature. Next, 0.860 g (5.00 mmol) of benzyl bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at room temperature. The precipitated solid was filtered, washed with acetonitrile, and then vacuum-dried to obtain 1.40 g of white solid 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide.

[0256] (Synthesis Example 44) <Compound 44:[SiW 12 O 40 ] 4- Synthesis of 4[2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium]> 0.523 g (0.150 mmol) of sodium 12-tungst(VI) silicate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 13.1 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 100 ml round-bottom flask and stirred at room temperature. To this, a solution of 0.486 g (1.20 mmol) of 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide obtained in Synthesis Example B above, dissolved in 13.1 g of dimethyl sulfoxide, was added dropwise. The mixture was stirred at room temperature, 26.2 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 13.1 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 13.1 g of methanol was added, and the supernatant was removed by centrifugation. Vacuum drying yielded 0.456 g of compound 44 as a white solid.

[0257] The FT-IR spectrum of the obtained compound 44 is shown in Figure 44.

[0258] (Synthesis Example 45) <Compound 45:[W6O 19 ] 2-Synthesis of 1.4(tetrabutylammonium)0.6[2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium] > In a 100ml eggplant-shaped flask, add [W6O 19 0.473 g (0.250 mmol) of [(tetrabutylammonium)2] and 11.8 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. To this, a solution of 0.405 g (1.00 mmol) of 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide obtained in Synthesis Example B above, dissolved in 11.8 g of dimethyl sulfoxide, was added dropwise. The mixture was stirred at room temperature, 23.7 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 11.8 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 11.8 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.390 g of compound 45 as a white solid.

[0259] The FT-IR spectrum of the obtained compound 45 is shown in Figure 45.

[0260] (Synthesis Example 46) <Compound 46:[Mo6O 19 ] 2- Synthesis of 1,2(tetrabutylammonium)0.8[2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium]> In a 100 ml eggplant-shaped flask, add [Mo6O 190.409 g (0.300 mmol) of [(tetrabutylammonium)2] and 10.2 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. To this, a solution of 0.486 g (1.20 mmol) of 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide obtained in Synthesis Example B above, dissolved in 10.2 g of dimethyl sulfoxide, was added dropwise. The mixture was stirred at room temperature, 20.4 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 10.2 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 10.2 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.355 g of compound 46, a yellow solid.

[0261] The FT-IR spectra of the obtained compound 46 are shown in Figure 46.

[0262] (Synthesis Example 47) <Compound 47:[V 18 O 42 ] 12- Synthesis of 12[2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium]> In a 50ml eggplant-shaped flask, [V 18 O 42 ]K 12 0.206 g (0.0100 mmol) and 5.15 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at room temperature. To this, a solution of 0.973 g (2.40 mmol) of 2-((4-azidobenzoyl)oxy)-N-benzyl-N,N-dimethylethane-1-aminium bromide obtained in Synthesis Example B above, dissolved in 10.3 g of dimethyl sulfoxide, was added dropwise. The mixture was stirred at room temperature, 10.3 g of pure water was added, and the mixture was stirred further at room temperature. The supernatant was removed by centrifugation. The process of adding 5.15 g of pure water and removing the supernatant by centrifugation was repeated twice. Finally, 5.15 g of methanol was added, the supernatant was removed by centrifugation, and the resulting solid was vacuum-dried to obtain 0.339 g of compound 47, a yellow solid.

[0263] The FT-IR spectrum of the obtained compound 47 is shown in Figure 47.

[0264] (Synthesis Example 48) <Synthesis of Compound 48: Bis-(triphenylsulfonium)-tungstate(IV)> Compound 51 was synthesized according to the synthesis method described in Japanese Patent Publication No. 2017-207532. Specifically, 2.00 g (5.12 mmol) of triphenylsulfonium iodide and 0.68 g (2.93 mmol) of silver oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 20 g of pure water in a 50 ml round-bottom flask and stirred at room temperature. The solid was then filtered off, and 0.57 g (2.28 mmol) of tungstic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to the resulting aqueous solution and stirred at room temperature. After stirring, the aqueous solution was filtered and concentrated, and then 5.00 g of propylene glycol monomethyl ether was added and the solvent was removed by distillation to obtain 1.25 g of compound 48, a white solid.

[0265] The results of measuring the content of elements V, Nb, Ta, Mo, and W for compounds 1 to 48 obtained above are shown in Table 1 below, along with theoretical values. Similarly, the content of the five elements was measured for 12-tungst(VI) silicate n-hydrate, and the results are shown in Table 1 below as compound 49.

[0266] [Table 1-1]

[0267] [Table 1-2]

[0268] (Example 1) 0.20 g of compound 1 was dissolved in 4.8 g of propylene glycol monomethyl ether (PGME) to prepare radiation-sensitive resist composition 1.

[0269] (Examples 2 to 48, Comparative Examples 1 to 2) Radiation-sensitive resist compositions 2-47 and comparative radiation-sensitive resist compositions 1-2 were prepared in the same manner as in Example 1, using compounds 2-49 instead of compound 1 and the solvents listed in Table 2 below instead of PGME.

[0270] [evaluation] (Fabrication of resist film) The radiation-sensitive resist compositions 1-47 and comparative radiation-sensitive resist compositions 1-2 obtained above were applied to a 4-inch silicon wafer using a spin coater. Subsequently, pre-baking was performed at 130°C for 60 seconds using a hot plate to obtain a resist film with a dry thickness of 50 nm.

[0271] (Irradiation of resist films and sensitivity evaluation) The sensitivity of radiation-sensitive resist compositions was evaluated by irradiation with electron beams (E-beams), which have a high correlation with sensitivity to extreme ultraviolet (EUV) light. Using an electron beam lithography system (ELS-7500, manufactured by Elionix Co., Ltd., accelerating voltage 50kV), electron beams were irradiated at two locations within a 50μm square area of ​​the resist film, with varying irradiation doses. The electron beam irradiation dose was 5000 μC / cm². 2 , and 10000 μC / cm 2 The resist film was then developed at 25°C for 1 minute using the developer listed in Table 2 below. After development, the film thickness was measured at two irradiated areas, and the sensitivity was evaluated.

[0272] For positive type, 5000 μC / cm 2 and 10000 μC / cm 2 ◎ indicates that no film remains in either of the two irradiated areas, and the irradiation level is 5000 μC / cm². 2 A circle (○) indicates that no film remains in the irradiated area, while a cross (×) indicates that the film remains in both irradiated areas.

[0273] For negative type, 5000 μC / cm 2 and 10000 μC / cm 2◎ indicates that a film thickness of 25 nm or more is obtained in both irradiation areas, and the temperature is 5000 μC / cm². 2 A score of ○ was given if a film with a thickness of 25 nm or more was obtained only in one of the irradiated areas, and a score of × was given if a film with a thickness of 25 nm or more was not obtained in either of the two irradiated areas.

[0274] Both positive and negative ratings are usable if they receive a ◎ or ○ rating.

[0275] The evaluation results are shown in Table 2 below. Details of the solvents and developers shown in Table 2 are as follows: PGME: Propylene glycol monomethyl ether H2O: Pure water NMP:N-methyl-2-pyrrolidone DMAc: N,N-dimethylacetamide CyHex: Cyclohexanone MeOH: methanol EtOH: Ethanol IPA: 2-Isopropanol BuOEtOH: Ethylene glycol monobutyl ether (2-butoxyethanol) Mixed solvent 1: methanol / pure water = 9 / 1 (mass ratio) Mixed solvent 2: N-methyl-2-pyrrolidone / propylene glycol monomethyl ether = 2 / 8 (mass ratio) Mixed solvent 3: N-methyl-2-pyrrolidone / propylene glycol monomethyl ether = 7 / 3 (mass ratio).

[0276] [Table 2-1]

[0277] [Table 2-2]

[0278] As is clear from Table 2 above, the radiation-sensitive resist compositions of Examples 1 to 48, containing compounds 1 to 47, showed good sensitivity to electron beams. On the other hand, the radiation-sensitive resist compositions of Comparative Examples 1 to 2, containing compounds 48 to 49, showed good sensitivity to an irradiation dose of 10,000 μC / cm². 2 However, sufficient sensitivity was not achieved.

Claims

1. An ionic salt (A) containing an anion (a) and an organic cation (b) having a metal chalcogenide cluster structure, Solvent (B) and, A radiation-resistant composition comprising, The anion (a) comprises at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. The organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a quaternary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms. A radiation-sensitive resist composition wherein the content of the ionic salt (A) in the total solid content of the radiation-sensitive resist composition is 20% by mass or more and 100% by mass or less.

2. The radiation-sensitive resist composition according to claim 1, wherein the anion (a) is at least one selected from the group consisting of anions represented by the following chemical formulas (a-1) to (a-6): 【Chemistry 1】 In the above general formula (a-1), M １ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m1 is an integer between 4 and 60, and multiple M １ They may be the same or they may be different. X １ is at least one selected from the group consisting of O, OH, S, and Se, n1 is an integer between 10 and 200, and multiple X １ They may be the same or they may be different. q1 is an integer between 2 and 40 (inclusive): 【Chemistry 2】 In the above general formula (a-2), M ２－１ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m²-1 is an integer between 4 and 60, and multiple M ２－１ They may be the same or they may be different. M ２－２ is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m²-2 is an integer between 1 and 10, and if m²-2 is 2 or greater, multiple M ２－２ They may be the same or they may be different. X ２ is at least one selected from the group consisting of O, OH, S, and Se, n2 is an integer between 10 and 200, and multiple X ２ They may be the same or they may be different. q2 is an integer between 2 and 40 (inclusive): 【Transformation 3】 In the above general formula (a-3), M ３ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m3 is an integer between 4 and 60, and multiple M ３ They may be the same or they may be different. X ３ is at least one selected from the group consisting of O, OH, S, and Se, n3 is an integer between 10 and 200, and multiple X ３ They may be the same or they may be different. R １ This is an organic group having 1 to 20 carbon atoms. r1 is an integer between 1 and 10, and if r1 is 2 or greater, multiple R １ They may be the same or they may be different. q3 is an integer between 2 and 40 (inclusive): 【Chemistry 4】 In the above general formula (a-4), M ４－１ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m4-1 is an integer between 4 and 60, and multiple M ４－１ They may be the same or they may be different. M ４－２ is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m4-2 is an integer between 1 and 10, and if m4-2 is 2 or greater, multiple M ４－２ They may be the same or they may be different. X ４ is at least one selected from the group consisting of O, OH, S, and Se, n4 is an integer between 10 and 200, and multiple X ４ They may be the same or they may be different. R ２ This is an organic group having 1 to 20 carbon atoms. r2 is an integer between 1 and 10, and if r2 is 2 or greater, multiple R ２ They may be the same or they may be different. q4 is an integer between 2 and 40 (inclusive): 【Transformation 5】 In the above general formula (a-5), M ５－１ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m5-1 is an integer between 4 and 60, and multiple M ５－１ They may be the same or they may be different. M ５－２ is at least one atom selected from the group consisting of P, As, Si, Ge, Sn, B, Al, Ga, In, Fe, Zn, Co, Te, Cu, Ag, and Mn. m5-2 is an integer between 1 and 10, and if m5-2 is 2 or greater, multiple M ５－２ They may be the same or they may be different. X ５ is at least one selected from the group consisting of O, OH, S, and Se, n5 is an integer between 10 and 200, and multiple X ５ They may be the same or they may be different. h is an integer between 1 and 10, R ３ This is an organic group having 1 to 20 carbon atoms. r3 is an integer between 1 and 10, and if r3 is 2 or greater, multiple R ３ They may be the same or they may be different. q5 is an integer between 2 and 40 (inclusive): 【Transformation 6】 In the above general formula (a-6), M ６ is at least one metal atom selected from the group consisting of V, Nb, Ta, Mo, and W. m6 is an integer between 4 and 60, and multiple M ６ They may be the same or they may be different. X ６ is at least one selected from the group consisting of O, OH, S, and Se, n6 is an integer between 10 and 200, and multiple X ６ They may be the same or they may be different. Z is an inorganic functional group comprising at least one atom selected from the group consisting of nitrogen, phosphorus, and sulfur atoms, and an oxygen atom. p is an integer between 1 and 10, and if p is 2 or greater, multiple Zs may be the same or different from each other. q6 is an integer between 2 and 40 (inclusive).

3. The radiation-sensitive resist composition according to claim 1, wherein the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a sulfonium cation having 1 to 30 carbon atoms, an iodonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a diazonium cation having 1 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms.

4. The radiation-sensitive resist composition according to claim 1, wherein the organic cation (b) is at least one selected from the group consisting of a secondary ammonium cation having 2 to 30 carbon atoms, a tertiary ammonium cation having 2 to 30 carbon atoms, a phosphonium cation having 1 to 30 carbon atoms, a pyridinium cation having 5 to 30 carbon atoms, an imidazolium cation having 3 to 30 carbon atoms, a guanidinium cation having 1 to 30 carbon atoms, and a hydrazinium cation having 1 to 30 carbon atoms.

5. The radiation-sensitive resist composition according to claim 1, wherein the molecular weight of the anion (a) is 600 or more and 9000 or less.

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

7. The radiation-sensitive resist composition according to claim 2, wherein q1 in the general formula (a-1), q2 in the general formula (a-2), q3 in the general formula (a-3), q4 in the general formula (a-4), q5 in the general formula (a-5), and q6 in the general formula (a-6) are each independently integers between 3 and 15.

8. The radiation-sensitive resist composition according to claim 1, wherein the molecular weight of the organic cation (b) is 50 or more and 5000 or less.

9. The radiation-sensitive resist composition according to claim 1, wherein the total molecular weight of the ionic salt (A) is 650 or more and 30,000 or less.

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

11. A radiation-sensitive resist composition according to any one of claims 1 to 10, which is of the positive type.

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