Tin compound, tin composition, methods for producing same, resist solution, pattern forming method, thin film, patterned thin film, and method for producing substrate

Abstract

Provided is a tin compound that has high performance as a resist material by having, in a well-balanced manner, characteristics such as solubility, hydrophobicity, and resist sensitivity.　The tin compound includes tin atoms, organic groups R, and oxo ligands and / or hydroxo ligands. A single molecule of the tin compound includes two types or more of the organic groups R, and an Sn-O-Sn structure. Each of the organic groups R has 1-30 carbon atoms.

Description

Tin compounds, tin compositions, methods for producing them, resist solutions, pattern forming methods, thin films, patterned thin films, and methods for producing substrates

[0001] The present invention relates to a tin compound, a tin composition, a method for producing the same, a resist solution, a pattern forming method, a thin film, a patterned thin film, and a method for producing a substrate.

[0002] In recent years, against the backdrop of a paradigm shift toward an advanced information society, there is a demand for faster, larger amounts of information to be handled with greater precision, and semiconductor device technology, such as integrated circuits using semiconductors, is advancing remarkably every day.

[0003] Evolution in semiconductor design has necessitated the creation of ever-smaller features on semiconductor substrate materials, with individual features measuring approximately 22 nanometers (nm) or less, and in some cases, less than 10 nm. One challenge in the fabrication of devices with such fine features is the ability to reliably and reproducibly create photolithography masks with sufficient resolution. Achieving feature sizes smaller than the wavelength of light requires the use of complex high-resolution techniques, such as multiple patterning. Thus, the development of photolithography techniques using shorter wavelength light, such as extreme ultraviolet (EUV) light, which has wavelengths of 10 nm to 15 nm (e.g., 13.5 nm), is becoming increasingly important.

[0004] Conventional organic chemically amplified resists (CARs) have potential drawbacks when used in EUV lithography, particularly because they have low adsorption coefficients in the EUV region, which can lead to blurred diffusion of photoactivated species, large line width roughness (LWR), pattern collapse, etc. Therefore, there remains a need for improved EUV photoresist materials that have the properties of higher sensitivity, lower line width roughness (LWR), and better etch resistance.

[0005] For this reason, metal materials using organotin compounds and the like have recently begun to be used as resists, particularly for EUV applications. Specifically, for example, alkyltin oxo-hydroxo compounds synthesized by hydrolysis of high-purity monoalkyltin compounds have been reported as resist materials for EUV applications, and it has been reported that they can achieve very fine negative patterning with high resolution and low line width roughness (LWR). It has also been reported that branched alkyl groups, in particular, have excellent sensitivity (Patent Document 1).

[0006] It has also been reported that when a monoalkyltin compound containing a small amount of dialkyltin compounds as impurities is used as a resist material, it is excellent in reducing outgassing (Patent Document 2).

[0007] It has also been reported that alkyltin oxo-hydroxo compounds synthesized using hydrolyzable tin compounds having multiple alkyl groups as raw materials can achieve both high sensitivity and low line width roughness (LWR) (Patent Document 3).An example of synthesizing an alkyltin oxo-hydroxo compound by mixing an organometallic compound having a hydrolyzable group but no alkyl group has also been reported (Patent Document 4).

[0008] Japanese Patent Application Laid-Open No. 2021-21953 Japanese Patent Application Laid-Open No. 2021-519340 Japanese Patent Application Laid-Open No. 2019-500490 Japanese Patent Application Laid-Open No. 2023-27078

[0009] However, the alkyltin oxo-hydroxo compounds reported to date have been insufficient to provide satisfactory performance as resist materials. In particular, the selection of alkyl group structure and compounding composition, which affect sensitivity and hydrophobicity, which are related to performance and quality, have not been optimized, and the preferred cluster structure and alkyl group composition in alkyltin oxo-hydroxo compounds have not been clarified.

[0010] Under these circumstances, the present invention provides a tin compound and / or a tin composition that has a good balance of properties such as solubility, hydrophobicity, and resist sensitivity, and can be used as a high-performance resist material.

[0011] The present inventors have conducted extensive research to solve the above problems and have found that the above object can be achieved by a tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, which has an Sn—O—Sn structure and contains two or more types of organic groups R in one molecule.

[0012] That is, the present invention has the following aspects: [1] A tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, wherein the tin compound contains two or more types of the organic group R in one molecule and has a Sn—O—Sn structure, and the organic group R has 1 to 30 carbon atoms. [2] The tin compound has a composition formula RSnO (3 / 2-X / 2) (OH) X [3] The tin compound according to [1], wherein the tin compound is represented by the chemical formula (RSn): 12 O 14 (OH)6 +2 [4] The tin compound according to any one of [1] to [3], wherein the organic group R has 3 to 10 carbon atoms. [5] The tin compound according to any one of [1] to [4], wherein the organic group R is a hydrocarbon group. [6] The organic group R is a hydrocarbon group, and 20 to 99 mol % of the substituents constituting the organic group R are secondary hydrocarbon groups R 2 [7] The tin compound according to any one of [1] to [5], wherein the organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are tertiary hydrocarbon groups R 3 [8] The tin compound according to any one of [1] to [5], wherein the organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are cyclic hydrocarbon groups R c [9] The tin compound according to any one of [1] to [5], wherein the organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are hydrocarbon groups R having an unsaturated bond. u

[10] The tin compound according to any one of [1] to [9], wherein the organic group R comprises an isopropyl group and a t-butyl group.

[11] The tin compound according to any one of [1] to

[10] , wherein the organic group R comprises an isopropyl group and a methylcyclopentyl group.

[12] The tin compound according to any one of [1] to

[11] , wherein the organic group R comprises a saturated hydrocarbon group.

[13] The tin compound according to any one of [1] to

[12] , wherein the organic group R comprises 50 mol % or more of isopropyl groups.

[14] A tin composition comprising the tin compound according to any one of [1] and [3] to

[13] , wherein the tin compound has the chemical formula (R A Sn) x (R B Sn) y O 14 (OH)6 +2 A tin composition comprising three or more tin compounds (P3AB) containing a cation represented by the formula: where x is an integer of 0<x<12, y is an integer of 0<y<12, and x+y=12 is satisfied. In the composition ratio of the organic group R calculated by NMR measurement of the tin composition, the organic group that occupies the largest proportion is designated as R A The organic group that accounts for the second largest proportion is R B The organic group R is the organic group R A and R B

[15] The tin composition according to

[14] , wherein the total content (%) of the tin compound (P3AB) calculated by the following formula A is 80% or more. <Formula A> Content (%) of the tin compound (P3AB) = [Peak intensity of the tin compound (P3AB)] / [Total peak intensity of the tin compounds (P3AB), (P3A), and (P3B)] The peak intensity refers to a peak intensity measured by ESI-MASS. The tin compound (P3A) is a single organic group R A The tin compound (P3B) refers to a tin compound containing only the single organic group R B

[16] The content (%) of the tin compound (P3AB-1) having the largest content (%) calculated by the above-mentioned calculation formula A is a tin compound containing only the single organic group R A

[17] The tin composition according to

[15] , wherein the content (%) of each of the tin compounds (P3AB), (P3A), and (P3B) in the tin composition is plotted on the y-axis, and the content (%) of the organic group R in one molecule is plotted on the y-axis. A The tin composition according to any one of

[14] to

[16] , wherein, in a distribution shape of a graph in which the number of tin compounds contained is plotted on the x-axis, when the tin compound with the highest content is tin compound (P3AB-1), the tin compound (P3AB-1) is at the peak top (maximum point) and the distribution structure is monoclinic.

[18] The tin composition according to any one of

[14] to

[17] , wherein the molecular weight distribution Mw / Mn calculated from the peak molecular weights (Mi) and contents (%) (Ni) of the tin compounds (P3AB), (P3A), and (P3B) in the tin composition is 1.00001 to 1.05.

[19] 119 The sum (k1 + k2) of the peak integral value sum (k1) of five-coordinate Sn (-250 to -350 ppm) and the peak integral value sum (k2) of six-coordinate Sn (-450 to -600 ppm) in Sn-NMR, 119 The tin composition according to any one of

[14] to

[18] , wherein the ratio [(k1 + k2) / (k3)] of the integral value of all peaks (including k1 and k2) in the range of 1000 to -1000 ppm detected by Sn-NMR to the total value (k3) is 0.9 or more.

[20] 119The tin composition according to any one of

[14] to

[19] , wherein the ratio (k1 / k2) of the sum of the peak integrals (k1) of pentacoordinated Sn (-250 to -350 ppm) in Sn-NMR to the sum of the peak integrals (k2) of hexacoordinated Sn (-450 to -600 ppm) is 0.5 to 2.5.

[21] A method for producing a tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, the method comprising the following steps: <Step 1> Blending two or more precursors RSnX3(A1) (wherein X in A1 is a hydrolyzable group) having different structures for the organic group R to obtain a precursor mixture. <Step 2> Contacting the blend of the precursor mixture and an organic solvent with liquid water.

[22] A method for producing the tin compound and / or tin composition according to

[21] , comprising a step of blending 100 parts by mass or more of an organic solvent relative to 100 parts by mass of the precursor mixture.

[23] A tin compound or tin composition produced by the production method according to

[21] or

[22] .

[24] A resist solution comprising the tin compound according to any one of [1] to

[13] and / or the tin composition according to any one of

[14] to

[20] and an organic solvent.

[25] A pattern formation method comprising the steps of applying the resist solution according to

[24] to a substrate, exposing the resist solution to radiation, and developing the resist solution using a developer.

[26] A thin film on a substrate, comprising the tin compound according to any one of [1] to

[13] and / or the tin composition according to any one of

[14] to

[20] .

[27] A patterned thin film on a substrate, comprising the tin compound according to any one of [1] to

[13] and / or the tin composition according to any one of

[14] to

[20] .

[28] A method for manufacturing a substrate, comprising the pattern forming method according to

[25] .

[0013] The tin compound and / or tin composition of the present invention has a well-balanced combination of properties such as solubility, hydrophobicity, and resist sensitivity, and can therefore be used as a high-performance resist material.

[0014] Figure 1 is an electrospray ionization mass spectrometry (ESI-MS) chart of tin hydrolysate H1. Figure 2 is an ESI-MS chart of tin hydrolysate H2. Figure 3 is an ESI-MS chart of tin hydrolysate H3. Figure 4 is an ESI-MS chart of tin hydrolysate H4. Figure 5A is an ESI-MS chart of tin hydrolysate H5. 119 FIG. 5B is a Sn-NMR chart of tin hydrolyzate H5. 1 FIG. 5C is a H-NMR chart of tin hydrolyzate H5. 13 5C-NMR chart. Fig. 5D is an ESI-MS chart of tin hydrolysate H5. Fig. 5E is an organic group R of each tin compound in the tin composition of tin hydrolysate H5. A 6A is a graph plotting the number of tin hydrolysates on the x-axis and the content (%) on the y-axis. 119 FIG. 6B is a Sn-NMR chart of tin hydrolyzate H6. 1 FIG. 6C is a H-NMR chart of tin hydrolyzate H6. 13 6D is a C-NMR chart of the tin hydrolyzate H6. FIG. 6E is an ESI-MS chart of the organic group R of each tin compound in the tin composition of the tin hydrolyzate H6. A 7A is a graph plotting the number of tin hydrolysates on the x-axis and the content (%) on the y-axis. 119 FIG. 7B is a Sn-NMR chart of tin hydrolyzate H7. 1 7C is an ESI-MS chart of the tin hydrolysate H7.

[0015] The present invention will be described below based on examples of embodiments for carrying out the present invention. However, the present invention is not limited to the embodiments described below. In the present invention, when "α to β" (α and β are arbitrary numbers) is used, it means "α or more and β or less," unless otherwise specified, and also includes "preferably more than α" or "preferably less than β." In the present invention, when "α or more" (α is an arbitrary number) or "β or less" (β is an arbitrary number) is used, it also includes "preferably more than α" or "preferably less than β." In the present invention, "γ and / or δ (γ and δ are arbitrary constituents or components)" refers to three combinations: γ only, δ only, and γ and δ. Regarding the numerical ranges described in stages in the present invention, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described herein, the upper or lower limit of the numerical range can be replaced with the values ​​shown in the examples. In the present invention, the term "main component" means a component that has a significant effect on the properties of the target object, and the content of the component is usually 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, and may be 100% by mass.

[0016] A tin compound and a tin composition according to one embodiment of the present invention are described in detail below. As defined in detail below, a tin compound refers to a compound represented by a single chemical formula. A tin composition refers to a mixture of tin compounds represented by multiple chemical formulas. For convenience, a "tin compound" and / or a "tin composition" synthesized by hydrolysis may be referred to as a "tin hydrolysate."

[0017] <<Tin Compound>> The tin compound (P1) according to one embodiment of the present invention is a tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, and is a tin compound containing two or more types of organic group R per molecule, and also containing an Sn—O—Sn structure, wherein the organic group R has 1 to 30 carbon atoms. Hereinafter, the substituent bonded to the tin atom may be referred to as a “ligand.”

[0018] Specifically, the tin compound (P1) is an organotin compound having multiple tin atoms and at least an Sn—O—Sn structure. Each tin atom typically has a ligand selected from an organic group R, an oxo ligand (Sn—O structure, Sn═O structure), and a hydroxo ligand (Sn—OH structure). In this embodiment, the organic group R in the tin compound (P1) must have two or more organic groups with different chemical structures. The tin compound (P1) may have multiple tin atoms in one molecule, each having an R—Sn bond, and may have two or more types of organic groups R, or one tin atom in one molecule may have two or more types of organic groups R. The presence of two or more types of organic groups R in one molecule of the tin compound (P1) can be confirmed by, for example, ESI-mass analysis.

[0019] The present tin compound (P1) is usually formed from the above-mentioned metal and ligand, but may contain other metal atoms and ligands (substituents) within the range that does not impair its properties.

[0020] The tin compound (P1) is synthesized by hydrolysis of RSnX3 (a monoalkyltin compound, sometimes referred to as a "precursor") as a main raw material, for example, using a method such as that disclosed in JP 2021-21953 A. (X is a hydrolyzable group [a substituent that can form an oxo ligand (Sn—O structure) or a hydroxo ligand (Sn—OH structure) by hydrolysis].)

[0021] By reacting RSnX3 with water or other suitable reagents under appropriate conditions by hydrolysis, condensation, or the like, tin hydrolysates represented by the following compositional formulas are obtained: RSnOOH (where x = 2), RSn(OH)3 (where x = 3), and condensates (where x = 1). These also react with each other to form condensates. Among these, tin compounds containing two or more types of organic groups R and containing an Sn-O-Sn structure are tin compounds (P2). Tin compounds (P2) are compounds containing tin atoms and organic groups, and containing oxo and / or hydroxo ligands. For example, they include compounds in which tin atoms (optionally containing hydroxo ligands) bearing organic groups form a network structure via the oxo ligands. [Formula] RSnO (1.5-(x / 2)) (OH) x (In the formula, 0≦x≦3)...(P2)

[0022] The reaction formula for obtaining the tin compound (P2) is shown below: (Reaction formula) RSnX3 + 3H2O → RSn(OH)3 + 3HX RSn(OH)3 → RSnO (1.5-(x / 2)) OH x + (x / 2) H2O

[0023] Among the compounds shown in the present tin compound (P1), tin compounds having a specific structure and number of tin atoms may be used as high-performance resist materials. For example, a compound containing a tin dodecamer (tin compound) represented by the chemical formula shown below is a stable football-shaped tin dodecamer cluster compound and is useful as a resist material. It is a cationic compound with the chemical formula shown below. [Formula] (RSn) 12 O 14 (OH)6 +2 ...(P3) (In the above formula, +2 represents a divalent cation.)

[0024] The tin compound (P3) is generally a divalent cationic compound that is stabilized by a counter anion (Z), and when combined with a monovalent counter anion (Z), the salt has the following chemical formula: [Formula] (RSn) 12 O 14 (OH)6(Z)2

[0025] The counter anion (Z) is not particularly limited, and examples thereof include an OH anion, an RCO2 anion, an HCO2 anion, an F anion, and a Cl anion.

[0026] As a specific example of the tin compound (P3), the synthesis examples described in the following document are known: (nBuSn) 12 O 14 (OH)6 +2 A report on the synthesis of: Eychenne-Baron et al., "New synthesis of the nanobuilding block {(BuSn) 12 O 14 (OH) 2+ and exchange properties of {(BuSn) 12 O 14 (OH)6}(O3SC6H4CH3)2", J. Organometallic Chemistry 1998, 567, 137-142

[0027] (iPrSn) 12 O 14 (OH)6 +2 Synthesis report: Puff et al. , "Zur hydrolyse von monoorganylzinn-tri halogeniden (III. mit dem nueartigen Kaefig-ion [(i-PrSn) 12 O 14 (OH)6 +2 These compounds have been identified by NMR, single crystal X-ray structure, etc., and the analytical results are cited as support in the examples of the present invention.

[0028] <Tin composition (M) containing tin compounds (P1), (P2), and (P3)> When tin compound (P1), (P2), or (P3) is produced by hydrolysis, a mixture containing tin compounds having multiple types of structures may be obtained. A mixture of multiple types of tin compounds (P1), (P2), or (P3) is called tin composition (M). Specific components constituting the mixture include tin compounds (P1), (P2), or (P3) containing multiple types of organic groups R per molecule, and multiple different types of organic groups R per molecule. Furthermore, a mixture of tin compounds (P1) or (P2) with different numbers of tin atoms per molecule or tin compounds (P1), (P2), or (P3) with different compositions of substituents (organic groups R, oxo ligands, hydroxo ligands) bonded to the tin atom may also be obtained, and such a mixture also corresponds to tin composition (M). The following description will be given using a specific example of a tin composition (M) containing a tin compound (P3), but these examples are equally applicable to cases containing tin compounds (P1) and (P2). The structure, number, and content of the multiple tin compounds (P3) contained in the tin composition (M) can be analyzed, for example, by ESI-mass spectrometry; specific analytical methods and examples are described below. The types of tin compounds (P3) contained in the tin composition (M) preferably have a lower limit of 3 or more, more preferably 5 or more, and even more preferably 7 or more, as detected by ESI-mass spectrometry. The upper limit is preferably 30 or less, more preferably 25 or less, more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less. When the number of tin compounds (P3) contained in the tin composition (M) is greater than the above-mentioned lower limit, it is possible to appropriately reduce crystallinity, which can impart appropriate solubility when used as a resist solution, and roughness can be reduced by preventing the generation of insoluble crystals during pattern formation. On the other hand, if the amount is less than the upper limit, the amount of tin compound (P3) having a different structure or molecular weight is small, so that a more uniform pattern can be formed, and roughness during pattern formation can be reduced in some cases.

[0029] [Organic Group R] The present tin compound (P1, P2, P3, hereinafter) contains an organic group R connected to a Sn atom. The organic group R has 1 to 30 carbon atoms. Considering the ease of elimination of the R group during EUV exposure and the vaporization of the generated component having the R group, the upper limit of the number of carbon atoms in the organic group R is 30 or less, preferably 20 or less, and more preferably 10 or less. From the viewpoint of the stability of the elimination component, the lower limit is 1 or more, preferably 2 or more, and more preferably 3 or more. Examples of the organic group R include halogenated hydrocarbon groups, hydrocarbon groups containing heteroatoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups. Among these, hydrocarbon groups are preferred because, when used as a resist, the outgassing generated upon elimination after exposure is hydrocarbon, which has minimal impact on semiconductor devices. When a heteroatom is contained, the organic group R is highly decomposable by EUV light, which may improve resist performance such as sensitivity.

[0030] When the organic group R is a hydrocarbon group, preferred specific examples of the hydrocarbon group include primary alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl; secondary alkyl groups such as isopropyl, isobutyl, sec-butyl, and isopentyl; tertiary alkyl groups such as t-butyl, t-amyl, cyclopentyl, cyclohexyl, methylcyclopentyl, and methylcyclohexyl; aryl groups such as phenyl, tolyl, benzyl, and naphthyl; aralkyl groups such as phenethyl, α-methylbenzyl, and 2-phenyl-2-propyl; alkenyl groups such as vinyl, 1-propenyl, allyl, and 3-butenyl; and alkyl groups substituted with a halogen atom such as 2-fluoroethyl and 2-iodoethyl. In terms of the effects of the present invention, it is preferable to use two or more of these organic groups R in combination.

[0031] Further examples of the structure include the following compounds: a and R bis an organic group having 1 to 10 carbon atoms, and examples of the organic group R include halogenated hydrocarbon groups, hydrocarbon groups containing heteroatoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups, and among these, hydrocarbon groups are preferred because when used as a resist, the outgassing generated when desorbed after exposure is hydrocarbon and has little effect on the semiconductor device. The substituent A on the aromatic ring is a halogen atom or an organic group having 1 to 10 carbon atoms, and examples of such organic groups include hydrocarbon groups containing heteroatoms such as nitrogen atoms, and hydrocarbon groups, and hydrocarbon groups are preferred.

[0032]

[0033]

[0034] (Preferred Hydrocarbon Group) Among the hydrocarbon groups shown above, the primary hydrocarbon group R 1 , a secondary hydrocarbon group R 2 , a tertiary hydrocarbon group R 3 a cyclic hydrocarbon group R c These hydrocarbon groups are classified into saturated hydrocarbon groups and unsaturated hydrocarbon groups such as , and may exhibit different properties when used as a resist material. When the hydrocarbon group is a saturated hydrocarbon group, it is preferred from the viewpoint of sensitivity (photoreactivity). In each classification, preferred substituents include primary hydrocarbon groups R 1 , a secondary hydrocarbon group R 2 , a tertiary hydrocarbon group R 3 From the viewpoint of sensitivity (photoreactivity) when used in an EUV resist, a secondary hydrocarbon group R that is easily eliminated is preferred. 2 , a tertiary hydrocarbon group R 3 is preferred, and the tertiary hydrocarbon group R 3 From the viewpoint of hydrophobicity, the tertiary hydrocarbon group R 3 is preferred from the viewpoint of controlling solubility because it can most effectively increase the hydrophobicity in the vicinity of the tin atom. However, if the hydrophobicity is too high, the secondary hydrocarbon group R 2 may be preferred.

[0035] (Mixture of Multiple Types of Organic Groups R) The present tin compound contains an organic group R, and the organic group R may be of multiple types. For example, two different organic groups R may be mixed as organic groups that occupy a major proportion of the organic group R.A and R B (Note that, by analyzing the composition of the organic group R by NMR, the organic group R that occupies the largest proportion calculated by the following formula may be referred to as "R A ", and the organic group that accounts for the second largest proportion is "R B ". The organic group R A and R B The organic group R may contain an organic group other than the above. A and R B The structure of R is selected from the above range of R, A and R B There are no particular limitations on the structure of the primary hydrocarbon group R 1 , a secondary hydrocarbon group R 2 , a tertiary hydrocarbon group R 3 In selecting the range of R A and R B It is preferable that different ranges are selected for the structures of "R A : Primary hydrocarbon group / R B : tertiary hydrocarbon group R 3 "," "R A : Secondary hydrocarbon group / R B : tertiary hydrocarbon group R 3 " is preferred, and among them, "R A : Secondary hydrocarbon group / R B : tertiary hydrocarbon group R 3 " is particularly preferred. That is, such "R A : Secondary hydrocarbon group / R B : tertiary hydrocarbon group R 3 " is particularly preferred in terms of the balance of performance as a resist material. (Calculation formula) Composition ratio (mol %) of each organic group = [H 1 -Ratio of each organic group R calculated from the integral value of NMR / H 1 -total proportion of all organic groups calculated from NMR integral value] × 100 The method for analyzing each organic group R by NMR is shown in the section "Compositional analysis of the present tin hydrolysate" below.

[0036] (Tin compounds containing a mixture of multiple organic groups R) For example, (RSn)12 O 14 (OH)6 +2 Regarding the tin compound (P3) containing a cation represented by the formula: A and R B If it consists only of A and R B The tin compound (P3AB) containing the following in one molecule is represented by the chemical formula (R A Sn) x (R B Sn) y O 14 (OH)6 +2 A tin compound containing a cation represented by the formula (P3AB), wherein x is an integer of 0<x<12, y is an integer of 0<y<12, and x+y=12.

[0037] The compounds represented here are specifically listed as tin compounds containing the following 11 types of cations. (R A Sn)1(R B Sn) 11 O 14 (OH)6 +2 , (R A Sn)2(R B Sn) 10 O 14 (OH)6 +2 , (R A Sn)3(R B Sn) 9 O 14 (OH)6 +2 , (R A Sn)4(R B Sn) 8 O 14 (OH)6 +2 , (R A Sn)5(R B Sn) 7 O 14 (OH)6 +2 , (R A Sn)6(R B Sn) 6 O 14 (OH)6 +2 , (R A Sn)7(R B Sn) 5 O 14 (OH)6 +2 , (RA Sn)8(R B Sn) 4 O 14 (OH)6 +2 , (R A Sn)9(R B Sn) 3 O 14 (OH)6 +2 , (R A Sn) 10 (R B Sn) 2 O 14 (OH)6 +2 , (R A Sn) 11 (R B Sn) 1 O 14 (OH)6 +2 .

[0038] As tin compounds that do not contain multiple types of organic groups R in one molecule, the tin compounds (P3A) and (P3B) shown below are expressed as follows: (R A Sn) 12 O 14 (OH)6 +2 Tin compounds containing cations represented by the formula (P3A) (R B Sn) 12 O 14 (OH)6 +2 As a supplementary note, the tin compounds (P3A) and (P3B) are tin compounds that do not contain multiple types of organic groups R, and therefore are not included in the tin compound (P3) of this embodiment.

[0039] (Method for detecting each tin compound in a tin composition) The structures and number of types of the tin compound (P3AB), tin compound (P3A), and tin compound (P3B) shown above can be analyzed and detected by ESI-mass, and specific analysis examples are shown in the Examples described below. The types of tin compounds (P3) contained in the tin composition (M) are preferably 3 or more types as a lower limit of the number detected by ESI-mass, more preferably 5 or more types, and even more preferably 7 or more types. The upper limit is preferably 30 or less types, more preferably 25 or less types, more preferably 20 or less types, even more preferably 15 or less types, and even more preferably 10 or less types.

[0040] Furthermore, the number of types of tin compounds (P3AB) contained in the tin composition (M) at a high ratio is more important in determining the resist properties. A preferred range for the number of types is a lower limit of two or more types, more preferably five or more types, and even more preferably eight or more types, as detected by ESI-mass spectrometry. The upper limit is preferably 10 or less types. When the number of types of tin compounds (P3AB) contained in the tin composition (M) is greater than the above-mentioned lower limit, it is possible to appropriately reduce crystallinity, thereby imparting appropriate solubility when used as a resist solution, and preventing the generation of insoluble crystals during pattern formation, thereby reducing roughness. When the number is less than the above-mentioned upper limit, it is possible to form a more uniform pattern due to the presence of fewer tin compounds (P3) having different structures or molecular weights, and it is possible to reduce roughness during pattern formation.

[0041] (Content of each tin compound in tin composition (M)) The content of each tin compound in the tin compound (P3AB), tin compound (P3A), and tin compound (P3B) shown above can be analyzed by quantifying the peak intensity of ESI-mass, and specific analytical examples are shown in the Examples described below. As a quantification method, the peak intensity shown in the ESI-mass chart of each of the tin compounds (P3AB), tin compound (P3A), and tin compound (P3B) is quantified, and the content (%) of each tin compound is calculated using the following formula: Content (%) of each tin compound (P3AB) = [Peak intensity of each tin compound (P3AB)] / [Total peak intensity of each tin compound (P3AB), (P3A), and (P3B)]

[0042] In this calculation formula, the content of each tin compound (P3AB), (P3A), and (P3B) for which no peak was detected is 0 (%), but the content of other tin compounds for which peaks were detected can be calculated. The total content (%) of each tin compound (P3AB) calculated by this calculation is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and even more preferably 80% or more. The upper limit is 100%. The higher this value, the lower the proportion of the tin compound (P3A) and tin compound (P3B) having a single organic group, which is preferable because it reduces the amount of tin compound (P3A) and tin compound (P3B) that remain in the resist solvent, improves filterability, and prevents crystallization, thereby improving storage stability.

[0043] (Content of Tin Compound (P3AB-1) with the Largest Content in Tin Composition (M)) The tin compound (P3AB) with the largest content (%) in the tin composition (M) was selected as (R A Sn) x' (R B Sn) y' O 14 (OH)6 +2 (P3AB-1), where x' is an integer in the range of 0<x'<12, y is an integer in the range of 0<y'<12, and x'+y'=12.

[0044] The upper limit of the content (%) of the tin compound (P3AB-1) calculated by the above formula is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, and particularly preferably 20% or less. The lower limit is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. When the content of the tin compound (P3AB-1) is within the above preferred range, a tin composition containing an appropriate amount of the compound that is the core of the composition can be obtained, thereby achieving a well-balanced crystallinity and uniformity, and enabling the formation of an excellent pattern. Furthermore, when the content of the tin compound (P3AB-1) with the highest content is a tin composition containing an appropriate amount of the compound that is the core of the composition, a resist material can be obtained that has a good balance between crystallinity and uniformity and is capable of forming ... A In this case, the proportion of the tin compound (P3A) having a single organic group is low, which can reduce the amount of tin compound that remains in the resist solvent, improve filterability, and prevent crystallization, thereby improving storage stability.

[0045] (Molecular Weight Distribution of Tin Compound (P3AB) in Tin Composition (M)) The content (%) of each tin compound (P3AB), (P3A), and (P3B) in the tin composition (M) is plotted on the y-axis, and the organic group R A Regarding the distribution shape of a graph plotting the number of tin compounds contained on the x-axis, it is preferable that the distribution structure be a single peak, with the tin compound (P3AB-1) with the highest content at the peak top (maximum point). If there are multiple peak tops, the molecular weight distribution will be broad, which may cause roughness during pattern formation. Furthermore, when dissolved in a resist solvent, the distribution of compounds with different solubilities will not be as broad, which may result in problems such as residual residue.

[0046] Furthermore, the number average molecular weight Mn, weight average molecular weight Mw, and molecular weight distribution Mw / Mn can be calculated from the peak molecular weight (Mi) and content (%) (Ni) of each tin compound (P3AB), (P3A), and (P3B). Specific calculation methods are shown below based on the formulas for calculating the molecular weight and molecular weight distribution of polymers. Number average molecular weight: Mn = Σ(Mi × Ni) / Σ(Ni) Weight average molecular weight: Mw = Σ(Mi 2× Ni) / Σ(Mi × Ni) ・Molecular weight distribution: Mw / Mn

[0047] The preferred molecular weight distribution value of the tin composition (M) calculated by this calculation formula is preferably 1.00001 or more as the lower limit, more preferably 1.00005 or more, and even more preferably 1.0001 or more. The upper limit is preferably 1.10 or less, more preferably 1.05 or less, even more preferably 1.01 or less, particularly preferably 1.005 or less, and especially preferably 1.002 or less. When the molecular weight distribution is below the above upper limit, the structures and molecular sizes of the tin compounds in the tin composition are uniform, which may reduce insoluble matter when dissolved in a resist solvent or reduce roughness during pattern formation. Furthermore, when the molecular weight distribution is above the above lower limit, the tin composition is a mixture of tin compounds with different molecular weights above a certain level, which may moderately reduce crystallinity, improve solubility, and improve storage stability in a resist solution.

[0048] (Cyclic Hydrocarbon Group) Regarding the organic group R, the cyclic hydrocarbon group R c When the compound contains R, the reactivity during exposure is improved due to the strain of the cyclic skeleton, which may be preferable from the viewpoint of resist sensitivity. c Examples of the cyclic skeleton contained in the organic group R include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. Among these, those having an alkyl group such as a methyl group at the 1-position (carbon bonded to Sn) may be preferred because they become tertiary hydrocarbon groups, and for example, 1-methyl-cyclopropyl, 1-methyl-cyclobutyl, 1-methyl-cyclopentyl, 1-methyl-cyclohexyl, and 1-methyl-cycloheptyl groups are preferred. c The proportion of is not particularly limited, but the upper limit is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and particularly preferably 30 mol% or less. The lower limit is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more.

[0049] (Organic group having an unsaturated bond) With respect to the organic group R, a hydrocarbon group R having an unsaturated bond u When the unsaturated bond is contained in the hydrocarbon group R, the unsaturated bond reacts or polymerizes during exposure, causing a change in structure, which may be preferable from the viewpoint of resist sensitivity. u Examples of skeletons having an unsaturated bond contained in include alkenes, alkynes, dienes, trienes, benzenes, etc., and alkenes are preferred from the viewpoint of reactivity and stability, and among these, terminal alkenes are preferred from the viewpoint of reactivity. Specific preferred examples include vinyl groups, 1-propenyl groups, allyl groups, 3-butenyl groups, 4-pentenyl groups, etc., and from the viewpoint of resist sensitivity, vinyl groups, 1-propenyl groups, and allyl groups in which the alkene is close to the Sn atom are preferred, and from the viewpoint of stability, it is preferred that the unsaturated bond is two or more carbon atoms away from the Sn atom. In view of the balance between these, allyl groups, 3-butenyl groups, etc. are preferred. The cyclic hydrocarbon group R in the organic group R c The proportion of is not particularly limited, but the upper limit is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and particularly preferably 30 mol% or less. The lower limit is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more.

[0050] (Preferred R A and R B Composition ratio of) Preferred R A and R B The most abundant organic group R is "R A ", and the second most common organic group is "R B ", then R A The content of the organic group R is preferably 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more of the substituents constituting the organic group R. The upper limit is preferably 99 mol % or less, more preferably 95 mol % or less, and even more preferably 90 mol % or less. The organic group R that occupies the main proportion in the organic group R A is in the above range, R AThe crystal formation during hydrolysis can be appropriately controlled to give a tin compound having suitable crystallinity without impairing the performance of the resist material. B The content of R is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and particularly preferably 30 mol% or less. The lower limit is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more. B When the composition of is within the above range, R A Without compromising the performance of R B In some cases, it may be possible to give the above characteristics or obtain a tin compound with appropriate crystallinity.

[0051] R A As the secondary hydrocarbon group R 2 is preferable, and among these, an isopropyl group is preferable. B As the tertiary hydrocarbon group R 3 , a cyclic hydrocarbon group R c , a hydrocarbon group R having an unsaturated bond u and the tertiary hydrocarbon group R 3 Among these, a t-butyl group is preferred. c Among these, a methylcyclopentyl group is preferred. u Among these, a butenyl group is preferred. A and R B In the combination of A and R B The upper limit of the difference in the number of carbon atoms between R and R is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The lower limit is preferably 0 or more, and more preferably 1 or more. A and R B When the difference in the number of carbon atoms between the organic group R A and R BSince the difference in molecular weight and hydrophobicity between the tin compounds are sufficiently close, the molecular weight distribution of the tin compound can be narrowed and the solubility in the resist solvent can be made uniform, which may reduce roughness during pattern formation. On the other hand, if the difference in molecular weight is equal to or greater than the above lower limit, the crystallinity may be appropriately reduced, which may improve the solubility in the resist solvent and the storage stability.

[0052] [Composition Analysis of the Tin Hydrolysate] The tin hydrolysate was analyzed by NMR ( 1 H-NMR, 13 C-NMR, 119 The composition of the organic groups contained can be analyzed using analytical devices such as Sn-NMR and their correlation NMR, mass spectrometry, etc. NMR can analyze the composition of the entire sample (composition of the tin composition), and can analyze information such as the ligands of the tin atom (organic group R, etc.), the coordination number per tin atom, etc., and can identify the structure of the organic group R and quantify the average composition of the organic group R in the sample (composition of the tin composition).

[0053] of this tin hydrolysate 119 In Sn-NMR, the ratio (k1 / k2) of the total peak integrals (k1) of pentacoordinate Sn (-250 to -350 ppm) to the total peak integrals (k2) of hexacoordinate Sn (-450 to -600 ppm) is preferably 0.5 to 2.5, more preferably 1.0 to 2.4, even more preferably 1.2 to 2.3, and particularly preferably 1.3 to 2.2. In this tin hydrolysate, pentacoordinate Sn tends to have OH groups, while hexacoordinate Sn tends to have more coordination moieties and therefore to have only Sn—O—Sn bonds with no OH groups bonded. In other words, the higher the k1 / k2 value, the greater the number of OH groups, and the lower the value, the fewer the number of OH groups. The number of OH groups affects the polarity of the tin compound, which affects its solubility in resist solvents, and the hydrophobicity and hydrophilicity parameters of the tin compound, which affect resist performance. From the viewpoint of controlling the balance of performance, it is preferable that k1 / k2 is controlled within the above range.

[0054] In mass analysis (mass spectrometry, sometimes referred to as "MS") (ESI-mass analysis (electrospray ionization) is particularly preferred from the viewpoint of sensitivity and the ability to detect unstable compounds through soft ionization), the molecular weight and molecular formula of each tin compound contained in the tin composition can be identified from the molecular weight of the ions observed. In other words, whereas what is observed in NMR is the average composition of the entire sample (tin composition), the composition of the organic group R observed in mass analysis represents the composition of the organic group R contained in one molecule (the composition in each tin compound). Furthermore, by quantifying the intensity of each peak, it is possible to identify the structure of the tin compound with the highest content in the tin composition and the composition of the organic group R of that tin compound, or to quantify the content of each tin compound. Since the tin atoms, oxygen atoms, carbon atoms, hydrogen atoms, etc. present in the tin compounds have isotopes, each tin compound gives a mass spectrum with multiple peaks, but only the peak with the greatest intensity from the theoretical mass spectrum pattern of each tin compound was analyzed as the peak of each tin compound, and the peak intensity was quantified. Examples of these analyses are also given in the Examples section.

[0055] (Purity of Tin Composition) The method for calculating the purity of a tin composition by NMR is shown below. Here, the "mol %" in terms of tin atoms, which represents the purity, is the ratio of tin atoms in the target compound to the number of tin atoms in all compounds containing tin atoms (including unidentified compounds). In practice, 119 The calculation is performed by using the sum of the integral values ​​of all peaks observed by Sn-NMR as the denominator and the integral value of the peak of the target compound as the numerator. 119 The measurement range of Sn-NMR is 1000 to -1000 ppm, which is the range in which the compound to be analyzed can be sufficiently measured. For example, the purity of a tin composition consisting of five-coordinate Sn and six-coordinate Sn is as follows: 119 Five-coordinate Sn in Sn-NMR 119The sum of the integral values ​​of the peaks of five-coordinate Sn (-250 to -350 ppm) in Sn-NMR (k1) and the integral value of the peaks of six-coordinate Sn (-450 to -600 ppm) (k2) is expressed as (k1+k2), 119 When k3 is the sum of all integrals of other peaks detected by Sn-NMR (in the range of 1000 to -1000 ppm, including k1 and k2), k1 is expressed as (k1 + k2) / (k3). The larger this value, the lower the concentration of impurities other than pentacoordinate Sn and hexacoordinate Sn in the tin hydrolyzate, and therefore, it is preferable. The lower limit is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.9 or more, particularly preferably 0.95 or more, and most preferably 0.99 or more. From the viewpoint of the measurement sensitivity of this method, if no peaks corresponding to k1 and k2 can be detected, it can be considered as 0.99 or more. The upper limit is 1.

[0056] According to this calculation method, only compounds containing tin atoms are included in the calculation. For example, even if additives or solvents are added according to the intended use after the present tin hydrolyzate is produced, the present tin hydrolyzate and other impurities such as tin compounds are included in the range of the present tin hydrolyzate as long as they contain the present tin hydrolyzate.

[0057] 119 In order to improve sensitivity, the Sn-NMR analysis method involves dissolving the tin hydrolyzate at a high concentration and performing the analysis (using a solvent that dissolves it at a high concentration), and obtaining the data under the following conditions: a large number of integration times (1,000 or more, preferably 10,000 or more), sufficient relaxation time (1 second or more), reverse gate decoupling, and an appropriate measurement range (1,000 to -1,000 ppm). As a result, by using these methods, the detection limit for trace amounts of tin compounds (A2), (A3), and (A4) can reach 0.01 mol%. In addition, if the sensitivity of the measurement peak is still insufficient, the detection sensitivity can be further increased to 0.001 mol% by using a high-sensitivity NMR (for example, a 600 MHz NMR using a cryoprobe).

[0058] ​In addition to the monoalkyltin compound (A1), the tin compounds that may be contained in the tin hydrolyzate include the following tin compounds (A2), (A3), and (A4): R2SnX2 (A2) SnX4 (A3) RSn(NR')2(N(R')CHNR'2) (A4)

[0059] [Crystallization of the Present Tin Hydrolysate] The present tin hydrolysate is preferably solid so that it can form a thin film as a resist material and be resistant to semiconductor processes (exposure, development, etching, etc.). In particular, controlling the properties of the solid, i.e., particle size, shape, crystallinity, and surface condition, within specific ranges may be preferable as a resist material. Crystallinity is particularly important because it allows for control of solubility (which contributes to development performance, coating performance, ease of filtration, and storage stability of the resist solution) and the solid's surface condition (which contributes to hydrophobicity / hydrophilicity, substrate adhesion, etc.) while maintaining the properties derived from the chemical formula. In addition, crystallinity also affects adhesion when applied to a substrate, post-exposure roughness and susceptibility to pattern collapse, solubility during development, and other factors, so it must be appropriately controlled within the range required for resist performance. Specifically, if the crystallinity is too high, dissolution in the resist solvent becomes difficult, causing problems during processes such as dissolution, filtration, and storage. Furthermore, if the crystallinity is too high during application and drying, cracking or collapse of the pattern may occur at the interface between crystals or on the crystal surface. During exposure and development, high crystallinity and large crystal size can lead to increased pattern roughness after development. On the other hand, if the crystallinity is too low, the resist film may have poor adhesion to the substrate or low strength, which can lead to peeling of the resist film during application, drying, exposure, development, etc., the pattern may collapse, or the pattern may become rough after development. As such, in resist materials with excellent solubility, adhesion, and roughness, an appropriate range of crystallinity exists, so it is necessary to appropriately control the ratio of crystalline components to amorphous components (non-crystalline) and control it within a specific crystallinity range.

[0060] Crystallinity can be analyzed by XRD (X-ray diffraction measurement), which can be applied to the tin hydrolyzate in the form of powder, molded body, thin film, or patterned thin film after exposure. Among the values ​​obtained from XRD, the diffraction angle 2θ (°) at the maximum intensity peak, the half-width (°) at the maximum intensity peak, and the number of detected peak tops can be used as numerical values ​​representing the crystallinity of the resulting tin compound. The analytical accuracy shown in this example is valid up to two decimal places, and when comparing the diffraction angle 2θ (°) and half-width (°), values ​​of 0.01 (°) or greater can be considered significant. Specific measurement methods are also shown in the examples.

[0061] The diffraction angle 2θ (°) of the peak with maximum intensity of the present tin hydrolyzate is preferably 5.00 to 15.00°, with the upper limit more preferably 3.00° or less, even more preferably 11.00° or less, particularly preferably 10.00° or less, and especially preferably 9.00° or less. The lower limit is more preferably 5.50° or more, even more preferably 5.80° or more, and particularly preferably 6.00° or more. The diffraction angle 2θ (°) of the peak with maximum intensity correlates with the lattice spacing of the crystals, and when it is in the above preferred range, the crystals of the present tin compound are arranged with an appropriate lattice spacing, and as crystals with appropriate crystallinity and strength during pattern formation, it is possible to suppress pattern collapse and simultaneously reduce roughness during fine pattern formation.

[0062] The half-width (°) at the maximum intensity peak is preferably in the range of 1.00 to 4.00°, with the upper limit being more preferably 3.50° or less, particularly preferably 3.00° or less, particularly preferably 2.50° or less, and particularly preferably 2.00° or less. The lower limit is more preferably 1.05° or more, even more preferably 1.10° or more, particularly preferably 1.20° or more, particularly preferably 1.43° or more, and particularly preferably 1.50° or more. The half-width (°) at the maximum intensity peak is particularly strongly correlated with the crystallinity of the tin compound, and when the half-width (°) is in the above-mentioned preferred range, parameters such as the solubility required for the resist material (contributing to development performance, coating performance, ease of filtration process, and storage stability of the resist solution) and the surface state of the solid (contributing to hydrophobicity / hydrophilicity, substrate adhesion, etc.) can be controlled within appropriate ranges.

[0063] The number of peak tops detected in the diffraction angle 2θ (°) range of 5.00 to 15.00° is preferably 5 or less, more preferably 3 or less, even more preferably 2 or less, and particularly preferably 1 or less. The lower limit is preferably 1 or more. Note that 0 indicates that no peak tops are detected by the above analytical method. For the present tin hydrolysate, the fewer the number of peak tops, the lower the crystallinity tends to be; however, 0 peak tops indicates that no crystalline structure is detected at all. In other words, when the number of peak tops is within the above preferred range, the resist material has appropriate crystallinity, and parameters such as solubility (contributing to development performance, coating performance, ease of filtration process, and storage stability of the resist solution) and solid surface condition (contributing to hydrophobicity / hydrophilicity, substrate adhesion, etc.) required for the resist material can be controlled within appropriate ranges.

[0064] [Solubility of the Present Tin Hydrolysate] When used as a resist material, the present tin hydrolysate may be dissolved in the resist solvent described below and used as a resist solution. The solubility of the present tin hydrolysate refers to the solubility when dissolved in the organic solvent used to prepare the resist solution. After dissolution, the resist solution is preferably completely dissolved, free of insoluble matter and turbidity derived from the present tin hydrolysate. Insoluble matter derived from the present tin hydrolysate can cause performance degradation and problems when used as a resist material. Specific examples include defects during patterning, resulting in performance degradation as a resist material (causing line width roughness (LWR), pattern collapse, and reduced sensitivity), equipment contamination due to impurities and foreign matter generated during etching, and clogging and reduced productivity in the filtration process.

[0065] (Resist Solvent) The tin hydrolyzate is dissolved in a resist solvent, which may be an organic solvent such as an alcohol, an ester, or a combination thereof. Particularly suitable solvents include aromatic compounds (e.g., xylene, toluene), ethers (anisole, tetrahydrofuran), halogenated solvents (dichloromethane, chloroform), esters (propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate), alcohols (e.g., 4-methyl-2-pentanol, 4-methyl-2-propanol, 1-butanol, methanol, isopropyl alcohol, 1-propanol), and mixtures of ketones (e.g., methyl ethyl ketone, cyclohexanone, 2-heptanone). These solvents may be used alone or in combination. Among these, alcoholic solvents are preferred for dissolving tin hydrolyzates having OH groups, with 4-methyl-2-pentanol being more preferred. From the viewpoints of toxicity, legal regulations, and volatility, 2-heptanone, 4-methyl-2-pentanol, and ethyl lactate are also preferred solvents in practical manufacturing processes.

[0066] The selection of these resist solvents may be based on the physical properties of the solvent itself, such as solubility parameter, volatility, flammability, toxicity, and viscosity. Alternatively, the resist solvent may be evaluated based on its stability (dissolution stability) when a tin hydrolyzate or other material is dissolved in the resist solvent. That is, after the components of the resist solution are dissolved and mixed, the properties of the dissolved tin hydrolyzate may change as a result of partial interactions (reaction, condensation, solvation, coordination, etc.) between the tin hydrolyzate and the solvent, particularly during the period from solution preparation to film formation. Solution stability due to these interactions is evaluated based on the storage stability of the resist solution, as described below. From the viewpoint of storage stability, alcoholic solvents are preferred due to stabilization through coordination with OH groups.

[0067] (Method for Evaluating Solubility) The solubility of the present tin hydrolysate was evaluated by comparing the turbidity (clarity) when the tin hydrolysate was dissolved at a certain concentration in 4-methyl-2-pentanol. Specifically, a mixed solution of 2.0% by mass of the tin hydrolysate in 4-methyl-2-pentanol was prepared as disclosed in JP-A-2019-500490, and the turbidity (clarity) of the resulting solution was visually confirmed by comparison with a standard turbidity solution to evaluate the solubility of the corresponding present tin hydrolysate. Kaolin turbidity standard solutions (0°C (clear), 50°C, 100°C, 500°C, 1000°C (white turbidity)) specified in JIS K0110 were used as the standard turbidity solutions, and the turbidity closest to that of each standard turbidity solution was evaluated as turbidity ratings 1 to 5 as follows: Turbidity rating 1: 0 degrees (transparent) Turbidity rating 2: 50 degrees Turbidity rating 3: 100 degrees Turbidity rating 4: 500 degrees Turbidity rating 5: 1000 degrees (cloudy)

[0068] [Storage Stability of Resist Solution] The resist solution prepared by dissolving the present tin hydrolyzate is required to be stable without stirring for at least one week, preferably two weeks or more, more preferably one month or more, even more preferably three months or more, and particularly preferably six months or more, without solid precipitation or sedimentation. A specific method for evaluating storage stability is to store the above solution sample at 20°C and perform a similar turbidity evaluation one week, two weeks, and one month after dissolution. For a resist solution to be stably stored, it is preferable that there be no change in turbidity in this evaluation.

[0069] <<Raw Materials for the Tin Hydrolysate>> In producing the tin hydrolysate as described above, it is preferable to use the monoalkyltin compounds (A1) and (B1) shown below as raw materials (sometimes referred to as "precursors"), although there are no particular limitations. The monoalkyltin compounds (A1) and (B1) that can be used as precursors are described below.

[0070] <Monoalkyltin Compound (A1)> The monoalkyltin compound (A1) is defined as follows. It is a compound in which one organic group and three hydrolyzable groups X capable of undergoing a reaction such as hydrolysis are bonded to tetravalent tin. Specifically, it is represented by the following general formula (A1): RSnX3 ... (A1) (In the general formula (A1), R is an organic group having 1 to 30 carbon atoms. X is selected from OR', NR'2, and C≡CR'. R' is an organic group having 1 to 10 carbon atoms. Examples of the organic group R' include halogenated hydrocarbon groups, hydrocarbon groups containing a heteroatom such as an oxygen atom or a nitrogen atom, and hydrocarbon groups. Among these, hydrocarbon groups are preferred because, when used as a resist, the outgassing generated when the compound is desorbed after exposure is hydrocarbon, which has little effect on the semiconductor device. Furthermore, when there are multiple R's in a molecule, they may have different structures, or they may be bonded to each other to form a cyclic structure.)

[0071] [Organic Group R] The organic group R has 1 to 30 carbon atoms. Examples of the organic group R include halogenated hydrocarbon groups, hydrocarbon groups containing heteroatoms such as oxygen and nitrogen atoms, and hydrocarbon groups. Among these, hydrocarbon groups are preferred because, when used as a resist, the outgassing generated upon elimination after exposure is hydrocarbon, and they have minimal impact on semiconductor devices. When a heteroatom is contained, the organic group R exhibits high decomposition properties with respect to EUV light, which may improve resist performance such as sensitivity. Considering the ease of elimination of the R group and vaporization of the generated R group component during EUV exposure, the upper limit of the number of carbon atoms in the organic group R is 30 or less, preferably 20 or less, and more preferably 10 or less. From the viewpoint of the stability of the elimination component, the lower limit is 1 or more, preferably 2 or more, and more preferably 3 or more.

[0072] The organic group R is preferably a hydrocarbon group because, when used as a resist, the outgassing generated upon desorption after exposure is hydrocarbon, and therefore the impact on the semiconductor device is minimal. Specific preferred hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, cyclopentyl, and cyclohexyl; aryl groups such as phenyl, tolyl, benzyl, and naphthyl; aromatic hydrocarbon groups such as aralkyl groups such as phenethyl, α-methylbenzyl, and 2-phenyl-2-propyl; alkenyl groups such as vinyl, 1-propenyl, allyl, and 3-butenyl; and alkyl groups substituted with halogen atoms such as 2-fluoroethyl and 2-iodoethyl. These groups may be used in combination of two or more.

[0073] Further examples of the structure include the following compounds: a and R b is an organic group having 1 to 10 carbon atoms. Examples of such organic groups include halogenated hydrocarbon groups, hydrocarbon groups containing hetero atoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups. The substituent A on the aromatic ring is a halogen atom or an organic group having 1 to 10 carbon atoms. Examples of such organic groups include hydrocarbon groups containing hetero atoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups.

[0074]

[0075]

[0076] The hydrocarbon groups shown above are primary hydrocarbon groups R 1 , a secondary hydrocarbon group R 2 , a tertiary hydrocarbon group R 3 and are typically alkyl or aralkyl groups. Preferred examples of each group include primary hydrocarbon groups R 1 R: a secondary hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an isobutyl group, a benzyl group, or a phenethyl group 2 R: a tertiary hydrocarbon group such as an isopropyl group, a sec-butyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, or an α-methylbenzyl group 3 Examples of such groups include t-butyl, t-amyl, 1-methyl-cyclopentyl, 1-methyl-cyclohexyl, and 2-phenyl-2-propyl groups. Each group may exhibit different properties when used in a resist material. The following describes hydrocarbon groups as representative examples. From the viewpoint of sensitivity (photoreactivity) when used in a preferred EUV resist, the secondary hydrocarbon group R that is easily eliminated is selected. 2 , a tertiary hydrocarbon group R 3 From the viewpoint of hydrophobicity, the tertiary hydrocarbon group R 3 is most preferable from the viewpoint of controlling solubility because it can increase the hydrophobicity in the vicinity of the tin atom. However, if the hydrophobicity is too high, the secondary hydrocarbon group R 2 is sometimes preferable. Furthermore, from the viewpoint of thermal stability, which affects distillation and the like, primary hydrocarbon groups tend to be less susceptible to disproportionation and the like, and may be easily purified. On the other hand, secondary and tertiary hydrocarbon groups are prone to disproportionation reactions, and secondary and tertiary hydrocarbon groups having a small carbon number (6 or less) in particular are unstable during distillation, and distillation with high purification efficiency is often difficult due to thermal decomposition and the like. Therefore, it is more important to obtain a high-purity tin compound with a low content of by-products with similar boiling points in the reaction stage prior to purification such as distillation.

[0077] [Substituent X] The structure of the substituent X is not particularly limited as long as it is a hydrolyzable group that can undergo a reaction such as hydrolysis. Preferred examples of the substituent X include OR', NR'2, and C≡CR' in terms of high reactivity, with OR' and NR'2 being more preferred in terms of hydrolysis reactivity. R' is an organic group having 1 to 10 carbon atoms, and examples of the organic group include halogenated hydrocarbon groups, hydrocarbon groups containing heteroatoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups. Furthermore, when there are multiple R's in a molecule, the structures may be different from each other, or they may be bonded to each other to form a cyclic structure. Among these, an alkoxy group is preferred as OR', and an alkylamino group is preferred as NR'2, in terms of the balance between high reactivity upon hydrolysis and stability during synthesis. Specific examples of the organic group R' include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a t-amyl group, a 2-methyl-pentyl group, a trifluoroethyl group, and a trifluoromethyl group. Examples of NR'2 include a 1-pyrrolidinyl group in which two substituents on the nitrogen are bonded to form a five-membered ring.

[0078] As a preferred substituent X, an alkyl group containing no heteroatoms or an alkyl group containing fluorine is preferred as the organic group R' from the viewpoint of low boiling point and stability. Furthermore, from the viewpoint of low boiling point, a smaller number of carbon atoms is preferred, while from the viewpoint of thermal stability and stability against moisture, a larger number of carbon atoms is preferred. Specific examples of substituent X that have an excellent balance of these properties include OR': t-butoxy group, t-amyloxy group, 4-methyl-2-pentaloxy group, trifluoroethoxy group, trifluoromethoxy group; and NR'2: dimethylamino group, diethylamino group, methylethylamino group, pyrrolidyl group, etc. Among these, OR' is preferred from the viewpoint of hydrolysis reactivity when used as a resist material, with dimethylamino group and diethylamino group being most preferred. NR'2 is preferred from the viewpoint of balance between stability and reactivity, with t-butoxy group, t-amyloxy group, and 4-methyl-2-pentaloxy group being most preferred.

[0079] Furthermore, R in the molecule and the organic group contained in the substituent X may be bonded to each other to form a cyclic structure. In this case, for example, compounds having the structure shown below may be mentioned.

[0080]

[0081] [Structure of Monoalkyltin Compound (A1)] The structure and physical properties of the monoalkyltin compound (A1) (hereinafter sometimes referred to as "tin compound (A1)") are not particularly limited as long as they fall within the above-mentioned ranges. However, when used as an EUV resist material, it may be preferable for the compound to have the following physical properties.

[0082] (Boiling point) When using the tin compound (A1), the boiling point at 1 torr is preferably 300°C or less, more preferably 250°C or less, even more preferably 200°C or less, and particularly preferably 150°C or less. The lower limit of the boiling point at 1 torr is usually 0°C or more, preferably 10°C or more, more preferably 20°C or more. A low boiling point allows distillation at low temperatures, which is preferable from the viewpoint of facilitating deposition when used as a resist material. When the boiling point is above the above lower limit, processes involving deposition and reaction at high temperatures tend to be easier when used as an EUV resist, and the thermal stability of the formed film is excellent, which tends to suppress volatilization and scattering of components and outgassing.

[0083] (Molecular Weight) The molecular weight of the tin compound (A1) is preferably 500 or less, more preferably 400 or less, and even more preferably 350 or less. The lower limit is preferably 150 or more, more preferably 180 or more, and even more preferably 200 or more. If the molecular weight is too high, the boiling point becomes too high, which may make deposition difficult when used as an EUV resist. If the molecular weight is too low, the boiling point becomes too low, which may make processes involving deposition or reaction at high temperatures difficult, or the thermal stability of the formed film may be insufficient, causing problems such as volatilization and scattering of components and outgassing.

[0084] (Molecular Weight Difference Between Organic Group R and Substituent X) There is no particular limitation on the molecular weight difference between the organic group R and the substituent X, but it is preferably 50 or less, more preferably 30 or less, even more preferably 20 or less, particularly preferably 10 or less, and especially preferably 6 or less. The lower limit is 0. By reducing the molecular weight difference between R and X, the mass difference of various outgases generated when used as a resist tends to be reduced, making it easier to set conditions in the EUV process. Furthermore, in order to control the EUV sensitivity and boiling point of the tin compound, the molecular weight difference may be adjusted by changing the substituent. On the other hand, as described below, the smaller the molecular weight difference between R and X, the smaller the molecular weight difference between the tin compound (A1) and impurities, which may make purification more difficult.

[0085] <Tin Compound (B1)> The tin compound (B1) of RSnX2Y is defined as follows. It is a compound in which one organic group R, two hydrolyzable groups X capable of undergoing a reaction such as hydrolysis, and one hydrolyzable group Y are bonded to tetravalent tin. Specifically, it is represented by the following general formula (B1): RSnX2Y ... (B1)

[0086] In the general formula (B1), R is an organic group having 1 to 30 carbon atoms, and examples of the organic group include halogenated hydrocarbon groups, hydrocarbon groups containing heteroatoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups, and two or more of these can be used in combination. X has the same meaning as above. X and Y are hydrolyzable groups with different chemical formulas, and OR' B , NR' B 2. C≡CR' B The R' is selected from the group consisting of B is an organic group having 1 to 10 carbon atoms, and examples of the organic group include a halogenated hydrocarbon group, a hydrocarbon group containing a hetero atom such as an oxygen atom or a nitrogen atom, and a hydrocarbon group. B In the case of 2, the R' B may be the same or different. B When there are a plurality of groups, they may have different structures, or may be bonded to each other to form a cyclic structure.

[0087] The tin compound (B1) is formed of two hydrolyzable groups X and one hydrolyzable group Y, which can undergo hydrolysis or other reactions, and therefore hydrolysis can proceed at unequal rates. Furthermore, by controlling the hydrolysis method, it is possible to preferentially react only specific substituents X and / or Y.

[0088] A preferred structure of RSnX2Y (B1) is one in which X is NR2 and Y is NR' from the viewpoint of hydrolysis reactivity. B 2 structure, and particularly, Y is N(R' B ) CHNR' B 2 is preferable in terms of adjusting the difference between X and Y upon hydrolysis.

[0089] [Tin Hydrolysate Containing Tin Compounds (A1) and (B1)] Although RSnX and RSnXY can each be hydrolyzed alone to form a tin hydrolysate, it is preferable to use a mixture containing (A1) and (B1), particularly in order to control the crystallinity without reducing the purity of the resulting tin hydrolysate. That is, the tin compound (A1) and the tin compound (B1) have the same organic group R, and the organic groups R remaining in the tin hydrolysate after hydrolysis are essentially equivalent, which is an important point and is different from the impurities contained in monoalkyl tin compounds having a structure different from (B1).

[0090] In the specific composition of the mixture (A1B1) containing the tin compounds (A1) and (B1) (the purity of the tin compounds (A1) and (B1) in the tin hydrolyzate), the purity of the tin compound (A1) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, particularly preferably 50 mol% or more, and especially preferably 70 mol% or more. The upper limit is preferably 99 mol% or less, more preferably 97 mol% or less, even more preferably 95 mol% or less, and especially preferably 90 mol% or less. The purity of (B1) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, particularly preferably 50 mol% or more, and especially preferably 70 mol% or more. The upper limit is preferably 99 mol% or less, more preferably 97 mol% or less, even more preferably 95 mol% or less, and especially preferably 90 mol% or less. The total content of the tin compounds (A1) and (B1) in the mixture (A1B1) is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more. A sufficiently high total content of the tin compounds (A1) and (B1) results in a highly pure tin hydrolyzate. When the total content of the tin compounds (A1) and (B1) is 80 mol% or more, the lower limit of the RSnX2Y content is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, even more preferably 0.5 mol% or more, particularly preferably 1 mol% or more, especially preferably 3 mol% or more, and even more preferably 5 mol% or more. The upper limit is preferably 30 mol% or less, more preferably 25 mol% or less, even more preferably 20 mol% or less, and especially preferably 15 mol% or less.

[0091] <Impurities> [Tin compounds as impurities] Tin compounds as impurities other than the above tin compounds (A1) and (B1) are not particularly limited, but typical examples of tin compounds as impurities include the following tin compounds (A2) and (A3). Tin compounds (A2) and (A3) are difficult to separate because they have similar structures and boiling points to tin compound (A1), making separation by distillation difficult, and they are generated by decomposition of tin compound (A1) during reaction, heating, etc. R2SnX2 (A2) SnX4 (A3)

[0092] In particular, when the boiling points of the tin compound (A1) and the tin compound (A2) or (A3) are close to each other, separation by distillation is often difficult, and suppression during the reaction and post-treatment is important. In cases where the tin compounds (A2) and (A3), which are impurities with similar boiling points, are contained, it is preferable to suppress the content of the tin compounds (A2) and (A3) after the reaction. The amount of the tin compounds (A2) and (A3) contained in the synthesized tin compound (crude product) after the reaction is preferably 3 mol% or less, more preferably 2 mol% or less, even more preferably 1 mol% or less, particularly preferably 0.5 mol% or less, especially preferably 0.3 mol% or less, and even more preferably 0.1 mol% or less, 0.05 mol% or less, and 0.03 mol% or less. The lower limit is 0 mol%.

[0093] (Boiling Point of Impurities) Here, the boiling point refers to the boiling point when compared under the same pressure, not limited to normal pressure, particularly at the pressure when distillation is carried out. When the boiling point difference is close, it means that the difference in boiling point between the tin compounds (A1) and (A2) is usually 50°C or less, preferably 30°C or less, more preferably 10°C or less, and even more preferably 5°C or less. The lower limit is 0°C. Furthermore, when the molecular weights of R and X are close, the difference in boiling point is close or the intermolecular interaction is strong, making separation often difficult. When the molecular weight difference between R and X is close, it means that the difference is usually 30 or less, preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less. The lower limit is 0.

[0094] As an example, the difference in molecular weight between iPrSn(NMe) (A1-1) and iPrSn(NMe) (A2-1) is small (294 g / mol and 293 g / mol, respectively). The difference is only 1 g / mol. Additionally, the polarity of the isopropyl group and the dimethylamino group are very similar, so the difference in boiling point between the tin compounds (A1-1) and (A2-1) is extremely small. Measurements of the boiling points of these compounds revealed that the difference between the two boiling points was within 2°C in the pressure range of 0.7 to 10 torr. In other words, distillation with high separation capability is required to obtain high-purity tin compound (A1-1).

[0095] Tin compound (A1) and its raw material tin compound (E1) (hereinafter sometimes referred to as the "raw material tin compound") can suffer from decomposition due to side reactions during the reaction and in subsequent post-treatment processes. For example, a disproportionation reaction between tin compounds (A1) and (E1) as shown in the following formula may occur, and this reaction can be accelerated or suppressed depending on various reaction conditions. Light-induced decomposition reactions can also occur, or the decomposition reaction can be accelerated by light and heat. Additionally, the presence of trace amounts of air, moisture, etc. can also promote decomposition.

[0096] (Decomposition of tin compounds)

[0097] [Other Impurities] In addition, when the tin compound (A1) is RSn(NR2)3, the following tin compound (A4) may be contained as an impurity in the synthesized tin compound: RSn(NR')2(N(R')CHNR'2) (A4)

[0098] The tin compound (A4) is generated by decomposition of the tin compound (A1), and its generation may be accelerated by heat, light, or a combination of these factors. For example, when the tin compound (A1) is iPrSn(NMe2)3 (A1-1), the impurity tin compound (A4) may be iPrSn(NMe2)2(NMeCHNMe2) (A4-1) represented by the following formula (A4-1). This is as follows: 119 Sn-NMR spectrum, 1 It has a chemical shift in H-NMR and can be identified and quantified.

[0099] 119 Sn-NMR (223.8 MHz; C6D6): δ -82ppm. 1 H-NMR (600 MHz; C6D6): δ 3.37 (s, 2H, CH2), 2.89 (s, 3H, Sn-NMe), 2.86 (s, 12H, Sn-(NMe2)2), 2.15 (s, 6H, NMe2), 1.68 (m, 1H, iPr), 1.33 (s, 6H, iPr).

[0100]

[0101] When X is a dialkylamino group (NR'2) (where R'2 is selected from a methyl group, a primary alkyl group, or a secondary alkyl group), the mechanism of formation of the aforementioned compound RSn(NR')2(N(R')CH2NR'2) is not clear, but structurally it is presumed that the nitrogen radical (.NR'2) generated by the elimination of one of the three dialkylamino groups possessed by the tin compound (A1) is inserted into the C-H bond next to the nitrogen atom of another nearby compound (A1). Specifically, as shown in the Examples, this compound can be produced by decomposing the tin compound (A1) by heating or light. Furthermore, the aforementioned compound RSn(NR')2(N(R')CH2NR'2) represents a case where R' is a methyl group, but it can also be produced when R' is a primary alkyl group such as an ethyl group (where R' is CH2R 1 That is, the compound (A1) is RSnN(CHR 1 )3, compound (A4) is represented by RSn[N(CHR 1 )2]2[N(CH2R 1 ) CHR 1 N(CH2R 1 ) 2]. When R' is a secondary alkyl group such as an isopropyl group (where R' is RCHR 2 R 3 That is, the compound (A1) is RSn[N(CHR 2 R 3 )2]3, compound (A4) is represented by RSn[N(CHR 2 R​3 )2]2[N(CHR 2 R 3 )CR 2 R 3 N (CHR 2 R 3 )2].

[0102] It may also contain a divalent tin compound, SnX2 (A8). When the tin compound (A1) is RSn(NR2)3, the following tin compound (A8-1) may be mentioned: Sn(NR'2)2 (A8-1)

[0103] From the viewpoint of obtaining a high-purity resist material, the content of the tin compound A8 is preferably 1.0 mol % or less, calculated as tin atoms, relative to the synthetic tin compound, more preferably 0.5 mol % or less, even more preferably 0.1 mol % or less, and particularly preferably 0.01 mol % or less. The lower limit is 0 mol %.

[0104] Furthermore, depending on the raw materials and manufacturing method used, impurities such as R3SnX and R4Sn, which are tin compounds with many hydrocarbon groups, may also be mixed in as impurities.

[0105] <Method for producing tin compound (A1)> The method for producing the tin compound (A1) is not particularly limited, and the tin compound (A1) can be produced by a conventionally known method. Specifically, examples of methods for producing a tin compound containing the tin compound (A1) as a main component for the purpose of obtaining the tin compound (A1) include the following production methods.

[0106] (Production Method 1) One example of a method for producing the tin compound (A1) is a method for synthesizing a synthetic tin compound by reacting a raw material tin compound (E1) with a reactant ((M1) or (M2)) in an organic solvent (S1) under specific conditions, with the aim of obtaining the tin compound (A1). As will be described in detail below, a typical reaction scheme for this production method is as follows: RSnY E 3(E1)+3MX(M1)→RSnX3(A1)+3MY E

[0107] In the manufacturing method 1, the raw material is a tin compound RSnYE This method is advantageous in that it is possible to increase the purity of RSnX3 (A1) by purifying 3, thereby obtaining high-purity RSnX3 (A1). In addition, since a tin compound into which an organic group R has been previously introduced is used as a raw material, it is possible to reduce impurities such as tin compounds A2, A3, and A4, which are impurities, compared to other methods, and to reduce impurities that are difficult to separate by distillation.

[0108] The material components used in the method for producing the tin compound (A1) will be described below.

[0109] [Raw material tin compound (E1)] The raw material tin compound (E1) is represented by the following formula: RSnY E 3 ... (E1) (In general formula (E1), R is an organic group having 1 to 30 carbon atoms. Examples of such organic groups include halogenated hydrocarbon groups, hydrocarbon groups containing hetero atoms such as oxygen atoms and nitrogen atoms, and hydrocarbon groups. Y E is selected from a halogen atom, OR', and NR'2. R' may be the same or different and is an organic group having 1 to 10 carbon atoms which may be substituted with a halogen. When there are multiple R's in a molecule, they may have different structures and may be bonded to each other to form a cyclic structure.

[0110] Organic group Y in the reaction formula E is an organic group that can be substituted by reaction with the reactant (M1), and the structure thereof is not particularly limited, but preferred examples thereof are organic groups selected from a halogen atom, OR', and NR'2, with halogen atoms being particularly preferred due to their high reactivity. Among these, Cl atoms are preferred because they have a good balance between stability and reactivity, are easy to purify by distillation or the like, and allow for the preparation of a raw material tin compound (E1) with a higher purity, and monoalkyltin chlorides are the most preferred.

[0111] Raw material tin compound RSnY E The purity of 3 can be increased by refining, and high-purity RSnY can be used as a raw material. EIt is preferable to use 3 because the amount of remaining impurities is small and a high-purity tin compound (A1) is increased. Specifically, the tin atom content is usually 95 mol% or more, preferably 97 mol% or more, more preferably 99 mol% or more, even more preferably 99.5 mol% or more, and particularly preferably 99.9 mol% or more. The upper limit is 100 mol%.

[0112] On the other hand, the impurities of tin compounds and moisture may contribute to stabilization, such as preventing crystallization of the target product, or may affect the reaction for synthesizing the tin compound (A1), and therefore it may be preferable that the impurity tin compounds are contained in an amount of 0.1 mol% or more, more preferably 0.2 mol% or more, and even more preferably 0.3 mol% or more. E 2. R3SnY E , R4Sn are each preferably 3 mol % or less, more preferably 2 mol % or less, even more preferably 1 mol % or less, and particularly preferably 0.1 mol % or less, calculated as tin atoms. On the other hand, from the viewpoint of contributing to stabilization, such as preventing crystallization of the target product, R2SnY E 2. R3SnY E , R4Sn may preferably be contained in an amount of 0.01 mol % or more, more preferably 0.1 mol % or more.

[0113] [Reactant (M1)] The reactant (M1) is a raw material tin compound (E1) (RSnY E 3) Organic group Y E The reactant (M1) is capable of a substitution reaction with MX, thereby producing the target tin compound (A1) (RSnX3). Preferred structures of the reactant (M1) include MX, MX2, MX3, etc. For example, when the reactant (M1) is MX, the theoretical reaction formula is as follows: RSnY E 3(E1)+3MX(M1)→RSnX3(A1)

[0114] In the reaction formula, M represents a metal atom of Group 1, Group 2, Group 12, or Group 13. When M is Group 1, it may be expressed as "MX", when it is Group 2 or Group 12, it may be expressed as "MX2", and when it is Group 13, it may be expressed as "MX3", and multiple Xs in the molecule may be different. Furthermore, X is as described in the above section. Specifically, when X is OR', examples include LiOR', NaOR', KOR', MgOR'2, and ZnOR'2, and from the viewpoint of high reactivity, LiOR', NaOR', and KOR' are preferred. When X is NR'2, examples include LiNR'2, NaNR'2, KNR'2, Mg(NR'2)2, Zn(NR'2)2, etc., of which LiNR'2, NaNR'2, and KNR'2 are preferred from the viewpoint of high reactivity, and Mg(NR'2)2 and Zn(NR'2)2 are preferred from the viewpoint of stability, and of these, LiNR'2 (lithium amides: lithium dimethylamide, lithium diethylamide, etc.) is most preferred from the viewpoint of ease of preparation of a highly pure reagent.

[0115] [Reactant (M2)] The reactant (M2) represents a compound selected from the reactant (M1) or a compound represented by the chemical formula HX. H represents a hydrogen atom, and X has the same meaning as that contained in the tin compound (A1). Examples of compounds corresponding to HX include HOR' (methanol, ethanol, t-butanol, 4-methyl-2-pentanol, etc.) and HNR'2 (dimethylamine, diethylamine, morpholine, etc.). Among the reactants (M2), from the viewpoint of reactivity, compounds selected from the reactant (M1) are preferred because of their high reactivity. From the viewpoint of preventing metal contamination after the reaction, compounds corresponding to HX, i.e., HOR' (methanol, ethanol, t-butanol, 4-methyl-2-pentanol, etc.) and HNR'2 (dimethylamine, diethylamine, morpholine, etc.) are preferred, and the raw material tin compound (E1) (RSnY E 3) Y E When is a highly reactive NR'2, the use of a compound corresponding to HX may give a high purity product without metal contamination.

[0116] (Amount of reactants (M1) and (M2)) In terms of molar equivalents relative to the starting tin compound (E1), the lower limit is preferably 3.00 eq or more, more preferably 3.03 eq or more, and most preferably 3.06 eq or more. The upper limit is preferably 10.00 eq or less, more preferably 8.00 eq or less, and even more preferably 7.00 eq or less. In some cases, a plurality of reactants (M1) and (M2) may be used in combination, and in such cases, it is preferable that the total molar equivalents of the reactants falls within this range.

[0117] (Method for Preparing Reactant (M1)) With regard to the temperature in the step of preparing reactant (M1), the lower limit temperature is preferably about −78° C. or higher, more preferably about −40° C. or higher, even more preferably about −20° C. or higher, particularly preferably about −10° C. or higher, and especially preferably −5° C. or higher. The upper limit temperature is preferably about 40° C. or lower, more preferably about 20° C. or lower, and even more preferably 15° C. or lower. In particular, when reactant (M1) is lithium amide, it must be prepared from an amine and an alkyllithium, and if the temperature is below the above upper limit, volatilization of the amine and decomposition of the alkylamide tend to be suppressed. Furthermore, if the temperature is above the above lower limit, the solubility of dimethylamide in the solvent tends to be excellent, and the appropriate viscosity tends to result in excellent stirrability.

[0118] The reaction time after dropwise addition during preparation of the reactant (M1) is preferably 0.5 hours (hereinafter, "hours" may be referred to as "h") or more as a lower limit, more preferably 1 hour or more, and even more preferably 2 hours or more. The upper limit is preferably 48 hours or less, more preferably 30 hours or less, and even more preferably 20 hours or less. If the reaction time is too short, the reactant (M1) may not be produced with sufficient purity, or in the case of a slurry, the reactant (M1) may be produced inhomogeneously due to insufficient mixing. If the reaction time is too long, the reactant (M1) may decompose, resulting in the generation of by-products or a decrease in the number of equivalents.

[0119] Furthermore, it is preferable to continue stirring the reactant (M1) after its preparation and use the reactant (M1) in this reaction within 3 to 48 hours after its preparation, in order to maintain the purity of the reactant (M1) and to control the water content in the reactant (M1).

[0120] (Method for Preparing Reactant (M2)) Reactant (M2) represents a compound selected from the reactants (M1) or a compound represented by the chemical formula HX. The method for preparing reactant (M1) is as described above and will be described for a compound represented by the chemical formula HX. Commercially available compounds of the chemical formula HX may be used as is, but to avoid contamination with impurities, moisture, or metals, it is preferable to use compounds that have been purified by distillation, adsorption, column chromatography, or the like. Alternatively, products that have been purified to semiconductor grade (EL grade) or dehydrated grade may be commercially available. The specific purity is preferably 95% or more by mass, more preferably 98% or more, even more preferably 99% or more, particularly preferably 99.9% or more, and especially preferably 99.99% or more. The upper limit is 100%. Preferred organic solvents for preparation are those shown in the organic solvent (S1) below. Specifically, the amount of metal contamination is preferably 100 ppm or less by mass of each metal element, more preferably 10 ppm or less, even more preferably 1 ppm or less, particularly preferably 100 ppb or less, and especially preferably 10 ppb or less. The lower limit is 0 ppb.

[0121] [Organic Solvent (S1)] In this production method, a raw material tin compound (E1), a reactant ((M1) or (M2)), and an organic solvent (S1) are used. The organic solvent (S1) is not particularly limited, but examples thereof include hydrocarbons (hexane, cyclohexane, heptane, decane, decalin, etc.), aromatics (benzene, toluene, xylene, anisole, etc.), ethers (THF (tetrahydrofuran), diethyl ether, TBME (t-butyl methyl ether), dibutyl ether, 3-methyl THF, THP (tetrahydropyran), 3-methyl THP, etc.), ketones (acetone, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), etc.), amides (DMF (NN dimethylformamide), DMAC (NN dimethylacetamide), etc.), esters (ethyl acetate, butyl acetate, etc.), and alcohols (methanol, ethanol, isopropanol, butanol, 4-methyl-2-pentanol, etc.). Preferred are aromatic, hydrocarbon, and ether solvents that do not readily react with the reactants. These solvents can be used alone or in combination of two or more. It is preferable that the solvent itself does not contribute to the formation of metal contaminants.

[0122] Particularly preferred are hydrocarbons and aromatic solvents, which have low solubility in inorganic salts and allow for easy removal of by-products such as inorganic salts by filtration or centrifugation after the reaction. Among these, toluene and hexane are currently the most preferred solvents because they allow for easy removal of the product under vacuum at low temperature after the reaction. On the other hand, ethers are preferred solvents for smoothly progressing the reaction due to their high solubility in organometallic reactants such as lithium dimethylamide. In other words, combining multiple solvents, such as hydrocarbons, aromatics, and ethers, can sometimes combine the advantages of these solvents. Furthermore, when HOR' (e.g., methanol, ethanol, t-butanol, 4-methyl-2-pentanol) or HNR'2 (e.g., dimethylamine, diethylamine, morpholine) is used as the reactant (M2), the reactant (M2) may also function as a solvent.

[0123] (Production Method 2) As an example, it is synthesized from a raw material tin compound SnX4 and a reactant RM or RMZ containing R. SnX4 + RM → RSnX3 + MX SnX4 + RMZ → RSnX3 + MXZ E In the above reaction formula, M represents a metal atom of Group 1, Group 2, Group 12, or Group 13, or a hydrogen atom. When M is a Group 1 or a hydrogen atom, it is expressed as "RM", and when M is a Group 2 or Group 12, it is expressed as "RMZ". E ", and for the 13th family, "RMZ E 2", and multiple Xs in the molecule may be different. Z E represents a halogen atom or R. E may be different. X is as described above. Specifically, when X is OR', ROH, RLi, RNa, RK, RMgZ E , RZnZ E Among these, RLi is preferred from the viewpoint of high reactivity, and RMgZ is preferred from the viewpoint of reaction selectivity in monoalkylation and low basicity, which can prevent decomposition of the target compound. E , RZnZ E Among these, RMgZ is most preferable. Furthermore, ROH is preferable from the viewpoint of preventing metal contamination.

[0124] Due to the reaction format, this method suffers from the problem of contamination with by-products containing multiple organic groups R. In relation to this point, the structure of RSnX3 (A1) for which this method is effective is a structure in which the organic group R is a tertiary alkyl group (e.g., t-butyl, t-amyl, 1-methyl-cyclopentyl, 1-methyl-cyclohexyl). In this case, the reactivity of the reactant RM is easily controlled with a bulky tertiary alkyl group, and multiple bulky tertiary alkyl groups are unlikely to be introduced onto the Sn atom, so there is a tendency to selectively obtain the target product to which one alkyl group is attached in good yield. In addition, the boiling points of by-products containing multiple organic groups R are different from those of the target product, making them easy to separate by distillation, which is another factor that makes this method effective.

[0125] (Production Method 3) As an example, a step a of producing MSnX3 from a reactant containing SnX2, a monoalkyltin compound as raw materials, and MX, and a step b of reacting the resulting MSnX3 with an alkylating agent RZ F SnX + MX → MSnX 3 (Process α) MSnX3+RZ F → RSnX 3 (Process β)

[0126] In the reaction formula, M represents a metal atom of Group 1, Group 2, Group 12, or Group 13. When M is Group 1, it may be represented as "MX", when it is Group 2 or Group 12, it may be represented as "MX2", and when it is Group 13, it may be represented as "MX3". Multiple Xs in a molecule may be different. X is as described in the above section. Specifically, when X is OR', examples include LiOR', NaOR', KOR', MgOR'2, and ZnOR'2, and from the viewpoint of high reactivity, LiOR', NaOR', and KOR' are preferred. When X is NR'2, examples include LiNR'2, NaNR'2, KNR'2, Mg(NR'2)2, and Zn(NR'2)2, and from the viewpoint of high reactivity, LiNR'2, NaNR'2, and KNR'2 are preferred. Among them, LiNR'2 is most preferred from the viewpoint of ease of preparation of a high-purity reagent. Alkylating Agent RZ F In this case, Z F is a halogen atom (F, Cl, Br, I), and among these, Br and I are preferred from the viewpoint of reactivity.

[0127] In this method, the organic group R is replaced with an alkyl halide RZ, which is easy to synthesize and obtain. F This method has the advantage that it can be introduced from the starting point. In this respect, it is effective when the organic group R is unstable and would cause decomposition or side reactions if applied to Production Methods 1 and 2. Specifically, it may be effective when the organic group R has a heteroatom, an unsaturated bond, or an aromatic ring.

[0128] (Distillation Purification) The synthesized tin compound (A1) (crude product) may be further purified by distillation. The crude product is distilled and purified, and the resulting product is referred to as a purified tin compound of tin compound (A1). The higher the proportion of tin compound (A1) in the purified tin compound, the better the resist performance. Therefore, the purity of the tin compound (A1) is preferably 96 mol%, more preferably 97 mol%, even more preferably 98 mol% or more, particularly preferably 99% mol% or more, particularly preferably 99.2 mol% or more, particularly more preferably 99.5 mol% or more, even more preferably 99.8 mol% or more, and most preferably 99.9 mol% or more. On the other hand, if the purity of the triaminotin compound is too high, the disproportionation reaction of the organic group R of the tin compound (A1) may cause decomposition or instability during storage or use. In this case, the purity is preferably 100.0 mol% or less, more preferably 99.9 mol% or less.

[0129] The inorganic impurities in the purified tin compound are preferably low in order to be used as a resist material. Specifically, the content of each inorganic impurity element is preferably 10 ppm or less, more preferably 1 ppm or less, even more preferably 0.1 ppm or less, and particularly preferably 0.01 ppm or less. The lower limit is 0 ppm.

[0130] If the purified tin compound does not reach a sufficient quality, other purification treatments (filtration, column purification, addition of adsorbents, reactants, etc.) may be carried out before or after distillation.

[0131] <<Application as a resist material>> <Method for producing the present tin hydrolyzate> The method for producing the present tin hydrolyzate preferably involves hydrolysis by the following steps: <Step 1> Blending two or more precursors RSnX3(A1) (wherein X in A1 is a hydrolyzable group) having different structures of the organic group R to obtain a precursor mixture. <Step 2> Contacting the blend of the precursor mixture and an organic solvent with liquid water.

[0132] In step 1, two or more types of precursors, i.e., a precursor mixture, are obtained. In this step, the precursor mixture is not hydrolyzed and its chemical structure does not change. The precursors are preferably mixed, for example, in a gaseous and / or liquid state, until a sufficiently homogeneous state is obtained to obtain a precursor mixture, which is then used in step 2. Therefore, step 1 is preferably performed under an inert gas atmosphere. In steps 1 and 2, it is not necessary to use other additives such as solvents. However, particularly in the case where a homogeneous mixture of liquid precursor mixtures (step 1) is blended with an organic solvent and the blend is contact-reacted (mixed) with liquid water (step 2), it is preferable to blend 100 parts by mass or more of the organic solvent per 100 parts by mass of the precursor mixture to form a composition.

[0133] In order to obtain a uniformly mixed precursor mixture in step 1, it is preferable to carry out step 1 using the following specific equipment and under the following mixing conditions. The tin composition (M) obtained from the mixture obtained under the preferred mixing conditions shown below will have a low proportion of tin compounds (P3A) and (P3B) each having only a single organic group R, resulting in a tin composition with a more uniform compositional and molecular weight distribution, which is preferable in that it can reduce residue in the resist solvent and improve filterability. It is also preferable in that it can suppress crystallization during storage and achieve improved storage stability.

[0134] On the other hand, if two or more precursors are not sufficiently uniformly mixed before proceeding to step 2 and hydrolysis is performed, the hydrolysis will proceed with the precursors being unevenly distributed, and the content (%) of each tin compound (P3AB) in the tin composition (M) may decrease, or the proportion of tin compounds (P3A) and (P3B) having only a single organic group R may increase. Furthermore, the distribution shape of a graph plotting the content (%) of each tin compound (P3AB), (P3A), and (P3B) in the tin composition (M) on the y-axis and the number of organic groups R per molecule on the x-axis may have a more non-uniform distribution with multiple peaks. Furthermore, the molecular weight distribution in the tin composition (M) tends to broaden.

[0135] <Apparatus and Conditions During Mixing> The container used during mixing in step 1 is not particularly limited, but is preferably a container equipped with a stirrer, and mixing is performed under mixing conditions that prevent precursor decomposition and impurity contamination. Specifically, preferred containers during mixing include glass containers, SUS containers, Teflon (registered trademark) containers, and containers made of composite materials thereof, all equipped with a stirrer. A container with a glass liquid-contacting surface is particularly preferred, as this prevents metal contamination and reduces precursor decomposition. As the stirrer, a blade-rotating stirrer such as a stirring blade or a stirring bar (magnetic stirrer) is preferred, as it can efficiently stir the liquid mixture. Furthermore, it is preferable that these containers and stirrers during mixing are thoroughly washed with ultrapure water and then thoroughly dried, as this sufficiently reduces the contamination of metals and halogens. The rotation speed of the stirrer is preferably 50 rpm or more, more preferably 100 rpm or more, more preferably 150 rpm or more, and even more preferably 200 rpm or more. The above-mentioned preferred range of rotation speed is preferable because it allows the preparation of a uniform mixture in a short time that does not cause decomposition. The mixing time is not particularly limited as long as the mixture is sufficiently uniform within a time range that does not cause decomposition of the precursor, but the upper limit is preferably within 12 hours, more preferably within 6 hours, even more preferably within 3 hours, particularly preferably within 1 hour, and especially preferably within 30 minutes. The lower limit is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 5 minutes or more.

[0136] The temperature during mixing is not particularly limited, but the upper limit is preferably 150°C or lower, more preferably 100°C or lower, even more preferably 50°C or lower, and particularly preferably 30°C or lower. The lower limit is preferably -20°C or higher, more preferably -10°C or higher, and even more preferably -5°C or higher. When the temperature during mixing is equal to or lower than the upper limit, it is possible to suppress the generation of impurities or insoluble matters due to decomposition of the precursor during mixing, and to suppress non-uniformity due to volatilization of the precursor or solvent. Furthermore, when the temperature is equal to or higher than the lower limit, it is possible to uniformly mix the precursors in a liquid state without crystallizing or eluting.

[0137] The inert gas filled in the container during mixing is preferably nitrogen or argon, and more preferably high-purity nitrogen or argon. Since the precursor compound may react with light and decompose, generating impurities and insoluble matters, mixing is preferably performed under light-shielded conditions.

[0138] <Solvent for Mixing in Step 1> When mixing in Step 1, a solvent is not necessarily required as long as the desired precursor mixture can be obtained, but using an organic solvent may enable more efficient mixing. In addition, it is preferable to use the same solvent as that used in the hydrolysis in the subsequent Step 2, since this eliminates the need for a solvent substitution step. Specific organic solvents are not particularly limited, but examples thereof include hydrocarbons (hexane, cyclohexane, heptane, decane, decalin, etc.), aromatics (benzene, toluene, xylene, anisole, etc.), ethers (THF (tetrahydrofuran), diethyl ether, TBME (t-butyl methyl ether), dibutyl ether, 3-methyl THF, THP (tetrahydropyran), 3-methyl THP, etc.), ketones (acetone, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), etc.), amides (DMF (NN dimethylformamide), DMAC (NN dimethylacetamide), etc.), esters (ethyl acetate, butyl acetate, etc.), halogens (dichloromethane, chloroform), and alcohols (methanol, ethanol, isopropanol, butanol, 4-methyl-2-pentanol, etc.). A combination of solvents that does not react with the precursor to be used is preferred. Specifically, in systems where the precursor structure contains an NR2 group or the like and is highly reactive, such as for hydrolysis, aprotic solvents are preferred, and specific examples of aprotic solvents include aromatic, hydrocarbon, ether, and halogen-based solvents. These solvents can be used alone or in combination of two or more. It is preferable that the solvent itself does not contribute to metal contaminants. Furthermore, in order to prevent hydrolysis during mixing, the water content in the solvent is preferably 100 ppm or less, more preferably 50 ppm or less, more preferably 30 ppm or less, and even more preferably 15 ppm or less. The lower limit is 0 ppm.

[0139] To obtain a gaseous precursor mixture in step 1, there are two methods: one is to place a mixture of two or more precursors in a container in advance and volatilize the mixture as a precursor mixture, and the other is to mix the vapors of two or more precursors in an apparatus such as a CVD apparatus or an ALD apparatus (including an attached mixer, piping, etc.).From the viewpoint of uniformly mixing precursors with different boiling points with good reproducibility, it is preferable to mix them at the location where hydrolysis step 2 is performed, that is, in an apparatus such as a CVD apparatus or an ALD apparatus (including an attached mixer, piping, etc.).

[0140] Next, in the case of carrying out hydrolysis using liquid water, it is preferable to prepare two or more precursors and a precursor mixture under an inert gas atmosphere (Step 1), and then bring a blend of the precursors and an organic solvent into contact with liquid water to carry out hydrolysis of the precursor mixture (Step 2). In this case, the organic solvent used in Step 2 is preferably a solvent that does not hydrolyze the precursor, and specifically, an aprotic solvent is preferred, and a dehydrated aprotic solvent is more preferred.

[0141] [Organic Solvent During Hydrolysis] In the present production method, the organic solvent is not particularly limited, but preferred examples include hydrocarbon-based organic solvents (hexane, cyclohexane, heptane, decane, decalin, etc.), aromatic-based organic solvents (benzene, toluene, xylene, anisole, etc.), ether-based organic solvents (THF (tetrahydrofuran), diethyl ether, TBME (t-butyl methyl ether), dibutyl ether, 3-methyl THF, THP (tetrahydropyran), 3-methyl THP, etc.), ketone-based organic solvents (acetone, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), etc.), amide-based organic solvents (DMF (NN dimethylformamide), DMAC (NN dimethylacetamide), etc.), ester-based organic solvents (ethyl acetate, butyl acetate, etc.), halogen-based organic solvents (dichloromethane, chloroform), and alcohol-based organic solvents (methanol, ethanol, isopropanol, butanol, 4-methyl-2-pentanol, etc.). Preferred are combinations of solvents that do not react with the precursor to be used. Specifically, in systems where the precursor structure contains an NR2 group or the like and is highly reactive, such as in hydrolysis, aprotic solvents are preferred, and specific examples of aprotic solvents include aromatic, hydrocarbon, ether, and halogen-based solvents. These solvents can be used alone or in combination of two or more. It is preferable that the solvent itself does not contribute to metal contaminants. Furthermore, the water content of the solvent is preferably 100 ppm or less, more preferably 50 ppm or less, more preferably 30 ppm or less, and even more preferably 15 ppm or less, in order to prevent uneven hydrolysis that occurs before adding water. The lower limit is 0 ppm.

[0142] <Equipment and Conditions for Hydrolysis> The equipment and container for hydrolysis in Step 2 are not particularly limited, but are preferably a container equipped with a stirrer and are preferably carried out under conditions that prevent precursor decomposition and impurity contamination. Specifically, preferred containers for hydrolysis include glass containers, SUS containers, Teflon containers, and containers made of composite materials thereof, all equipped with a stirrer. Glass containers, SUS containers, Teflon containers, and containers made of composite materials thereof are particularly preferred, with glass containers having a liquid-contacting surface being particularly preferred because this prevents metal contamination and reduces precursor decomposition. Rotating blade stirrers, such as stirring blades and magnetic stirrers, are preferred because they can efficiently stir the liquid mixture. Furthermore, these containers and stirrers for hydrolysis are preferably thoroughly washed with ultrapure water and then thoroughly dried to ensure sufficiently low contamination with metals and halogens. The rotation speed of the stirrer is preferably 50 rpm or higher, more preferably 100 rpm or higher, more preferably 150 rpm or higher, and even more preferably 200 rpm or higher. The preferred rotation speed range is preferred because it allows a uniform hydrolysis reaction to be carried out in a shorter time. The mixing time is not particularly limited as long as the precursors are mixed sufficiently uniformly within a time range that does not cause decomposition, but the upper limit is preferably 12 hours or less, more preferably 6 hours or less, even more preferably 3 hours or less, particularly preferably 1 hour or less, and especially preferably 30 minutes or less. The lower limit is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 5 minutes or more. The temperature during hydrolysis is not particularly limited, but the upper limit is preferably 150°C or less, more preferably 100°C or less, even more preferably 50°C or less, and particularly preferably 30°C or less. The lower limit is preferably -20°C or more, more preferably -10°C or more, and even more preferably -5°C or more. A mixing temperature of less than the upper limit tends to suppress the generation of impurities or insoluble matter due to decomposition of the precursor during mixing, and to suppress non-uniformity due to volatilization of the precursor or solvent. Furthermore, a temperature above the lower limit tends to enable the precursors to be mixed uniformly in a liquid state without crystallization or elution.The inert gas filled in the vessel during hydrolysis is preferably nitrogen or argon, and more preferably high-purity nitrogen or argon. Since the precursor compound may react with light and decompose, producing impurities or insoluble matter, it is preferable to perform mixing under light-shielded conditions.

[0143] <Method for forming a thin film containing the present tin hydrolysate> The present tin hydrolysate (P1) shown above can be used as a resist material. Regarding its use as a resist material, for example, the method disclosed in JP 2021-21953 A can be used. For use as a resist material, there are two methods for forming a thin film (coating layer, coating film, etc.) containing the present tin hydrolysate on a substrate, for example, the dry method and the wet method described below.

[0144] In the dry method, the raw material for tin hydrolysate, a monoalkyltin compound (precursor), is vaporized under heat or reduced pressure and used as a vapor. The precursor vapor or the precursor deposited on a substrate is reacted with water vapor or other gases to synthesize the tin hydrolysate. By carrying out this method on a substrate, a thin film (coating film) containing the tin hydrolysate can be formed on the substrate. If necessary, the formation of the tin hydrolysate can be accelerated by combining reaction, heating, washing, or other processes before and after this process.

[0145] In the wet method, a raw material containing a monoalkyltin compound (precursor), which is the raw material for the tin hydrolyzate, is reacted with water or the like in solution or solid state to hydrolyze the tin hydrolyzate. The tin hydrolyzate can then be used as a coating solution by dissolving it in an organic solvent or the like. Alternatively, a solution containing the precursor may be first applied to a substrate, and then part or all of the above hydrolysis process may be carried out on the substrate before the tin hydrolyzate is produced.

[0146] In the coating step, the coating can be applied to a substrate by any coating or printing technique, and a thin film (coating film) containing the tin hydrolyzate can be formed on the substrate.

[0147] In the above-mentioned wet thin film formation method, the generation of tin hydrolyzate by hydrolysis in step 2 can occur either before or after the formation of a thin film. Of these two cases, in order to produce a tin composition (M) having multiple organic groups with an appropriate composition and distribution, it is preferable to perform the hydrolysis before the formation of a thin film using the preferred hydrolysis method in step 2 described above. When the hydrolysis is performed before the formation of a thin film, the tin composition (M) reacts with water while being appropriately mixed, allowing for uniform hydrolysis, resulting in the synthesis of a more uniform tin composition (M). That is, when the film is subsequently formed, a thin film containing a more uniform tin composition (M) with a lower proportion of tin compounds (P3A) and (P3B) having only a single organic group R and a more uniform composition distribution and molecular weight distribution can be obtained.

[0148] On the other hand, when hydrolysis is performed after film formation, the tin composition (M) becomes non-uniform because the hydrolysis proceeds in a state where the film is formed unevenly and cannot be sufficiently mixed. Specifically, examples include a case where a film is formed without hydrolysis occurring when the resist solution is applied to the substrate, and then hydrolysis is performed using water or the like after film formation. In such a case, the content (%) of each tin compound (P3AB) in the tin composition (M) in the thin film after hydrolysis may decrease, or the proportion of tin compounds (P3A) and (P3B) having only a single organic group R may increase. Furthermore, with respect to the distribution shape of a graph plotting the content (%) of each tin compound (P3AB), (P3A), and (P3B) in the tin composition (M) in the thin film on the y-axis and the number of organic groups R per molecule on the x-axis, the distribution may be more non-uniform with multiple peaks. Furthermore, the molecular weight distribution in the tin composition (M) tends to broaden.

[0149] <Patterning of Thin Films> The thin film obtained by any of the above methods may be stabilized or partially condensed by drying, heating, etc., before irradiation with light. Generally, the thin film (coating film) is thin, e.g., having an average thickness of less than 10 microns, although very thin submicron films, e.g., about 100 nm or less, even 50 nm or less, and particularly 30 nm or less, may be desired for patterning very small features. The resulting thin film (coating film) can be referred to as a "resist" because exposure to light treats the composition so that portions of the composition are resistant to development / etching.

[0150] The thin film (coating film) can be exposed to appropriate radiation, such as extreme ultraviolet, electron beam, or ultraviolet radiation, using a selected pattern or the negative of the pattern to form a latent image with developer-resistant and developer-soluble areas. After exposure to the appropriate radiation and before development, the thin film can be heated or otherwise reacted to differentiate the latent image from non-irradiated areas. The latent image is then contacted with a developer to form a physical image, i.e., a patterned thin film. The patterned thin film can be further heated to stabilize the remaining patterned thin film on the surface. The patterned thin film can be used as a physical mask to perform further processing according to the pattern, such as etching the substrate and / or depositing additional materials. After using the patterned thin film as a resist as desired, the remaining patterned thin film can be removed at an appropriate point in processing, or the patterned thin film can be incorporated into a final structure.

[0151] The conditions for each process are described in more detail below.

[0152] <Preparation and Filtration of Resist Solution> Generally, the resist solution used in the wet method is prepared by thoroughly mixing using an appropriate mixing device suitable for the volume of the material to be formed. Any contaminants or other insoluble components can be removed using appropriate filtration. In some embodiments, the prepared resist solution may be mixed and used. In addition to the tin compound as the main component, various additives may be added to the resist solution.

[0153] <Coating onto a Substrate> The precursor for dry processes and the resist solution for wet processes are selected based on their adhesion to the substrate and subsequent processability. The precursor for dry processes and the resist solution for wet processes are generally applied to the substrate surface. The substrate may include multiple layers on its surface. In some embodiments, the substrate surface may be treated to promote adhesion of the precursor for dry processes and the resist solution for wet processes. The substrate surface may also be cleaned and / or smoothed as needed. Suitable substrate surfaces can include any reasonable material. Some substrates of particular interest (e.g., silicon wafers, silica substrates) contain other inorganic materials, such as ceramic materials, polymeric substrates, organic polymers, composites thereof, and combinations thereof, on and / or within the substrate surface layer. While wafers, such as relatively thin circular structures, can be convenient substrates, any reasonably shaped structure can be used.

[0154] Polymer substrates or substrates having a polymer layer on a non-polymeric structure may be desirable for certain applications due to their low cost and flexibility. Such polymers may be selected based on the relatively low processing temperatures that can be used to process the patterning materials described herein. Such polymers preferably include, for example, polycarbonates, polyimides, polyesters, polyalkenes, copolymers thereof, and mixtures thereof.

[0155] Generally, it is desirable for the substrate to have a flat surface, particularly for high-resolution applications. However, in certain embodiments, the substrate may have substantial topography, and the resist coating is intended to fill or planarize features for certain patterning applications. Such functionality of resist materials is described in U.S. Patent Application Publication No. 2015 / 0253667 (Bristol et al.), entitled "Pre-Patterned Hard Mask for Ultrafast Lithographic Imaging," which is incorporated herein by reference.

[0156] Generally, any suitable coating process can be used to coat the substrate with the precursor (dry method) or the resist solution (wet method). Examples of suitable coating methods include, for example, spin coating, spray coating, dip coating, knife-edge coating, and printing methods (e.g., inkjet printing and screen printing) for wet methods, while dry methods include vapor deposition methods such as physical vapor deposition and chemical vapor deposition. While some of these coating methods form patterns during the coating process, the resolution currently achieved by printing and the like is significantly lower than that achieved by the radiation-based patterning described herein. To provide greater control over the coating process, the coating material can be applied in multiple coating steps. For example, multiple spin coatings can be performed for wet methods, and multiple vapor depositions can be performed for dry methods to achieve the desired final coating thickness. The heat treatment described below can be applied after each coating step or after multiple coating steps.

[0157] When patterning is performed using radiation, spin coating can be a desirable means for achieving a relatively uniform coating of the substrate, although edge effects may exist. In some embodiments, the wafer may be spun at a speed of about 500 to about 10,000 rpm, in further embodiments about 1,000 to about 7,500 rpm, and in additional embodiments about 2,000 to about 6,000 rpm. The rotation speed may be adjusted to achieve the desired coating thickness. Spin coating may be performed for a time period of about 5 seconds to about 5 minutes, and in further embodiments about 15 seconds to about 2 minutes. An initial slow rotation speed (e.g., 50-250 rpm) may be used to perform an initial bulk application of the composition across the entire substrate. To remove any edge bead, a backside rinse, edge bead removal step, or the like, using water or other suitable solvent may be performed. A person of ordinary skill in the art will recognize that additional ranges of spin coating parameters within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0158] The thickness of a coating film generally tends to depend on the concentration, viscosity, and spin-coating rotation speed of the resist solution for wet processes, and on the deposition pressure for dry processes. For other coating processes, the thickness can also generally be adjusted by selecting coating parameters. In some embodiments, it may be desirable to use a thin coating to facilitate the formation of small and highly modified features in a subsequent patterning process. For example, the coating film after drying can have an average thickness of about 10 μm or less, in other embodiments about 1 μm or less, in further embodiments about 250 nm or less, in additional embodiments about 1 to about 50 nm, in other embodiments about 2 to about 40 nm, and in some embodiments about 3 to about 25 nm. One of ordinary skill in the art will recognize that additional ranges of thickness within the explicit ranges above are contemplated and are within the scope of the present disclosure. The thickness can be evaluated using non-contact methods of X-ray reflectivity and / or ellipsometry based on the optical properties of the film. Generally, the coating film is relatively uniform to facilitate processing. In some embodiments, the coating film thickness varies by no more than ±50% from the average coating thickness, in further embodiments by no more than ±40%, and in additional embodiments by no more than about ±25% relative to the average coating thickness. In some embodiments, such as highly uniform coatings on larger substrates, evaluation of coating uniformity may be evaluated using a 1 cm edge exclusion; that is, coating uniformity is not evaluated within 1 cm of the coating edge. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the present disclosure.

[0159] The coating process itself may result in evaporation of some of the solvent, as multiple coating processes form droplets or other forms of coating material with larger surface areas and / or solution migration that stimulates evaporation. Solvent evaporation tends to increase the viscosity of the coating material as the species concentration in the material increases. The goal during the coating process is to remove enough solvent to allow the active substances in the dry precursor and wet resist solution to react and stabilize for further processing. That is, solvent may be removed, hydrolyzed tin compounds may form, or condense during the coating process or subsequent heating steps. Typically, the dry precursor and wet resist solutions may be heated prior to radiation exposure to promote densification. In the dried coating film, the dry precursor and wet resist solutions generally form a polymeric metal-oxo / hydroxo network based on oxo-hydroxo ligands to the metal, where the metal also has a molecular solid composed of some hydrocarbon groups or polynuclear metal-oxo / hydroxo species with hydrocarbon groups.

[0160] For wet processes, the solvent removal process may or may not be quantitatively controlled with respect to the specific amount of solvent remaining in the coating material, and empirical evaluation of the properties of the resulting resist solution may generally be performed to select processing conditions that are effective for the patterning process. While heating is not required for successful process application, it may be desirable to heat the coated substrate to accelerate processing and / or increase process reproducibility. In embodiments where heating is applied to remove solvent, the coated substrate with the coating film may be heated to about 45 to about 250°C, and in further embodiments, about 55 to about 225°C. Heating for solvent removal may generally be carried out for at least about 0.1 minutes, in further embodiments, from about 0.5 to about 30 minutes, and in additional embodiments, from about 0.75 to about 10 minutes. Those skilled in the art will recognize that additional ranges of heating temperature and time within the explicit ranges above are contemplated and are within the scope of the present disclosure. As a result of heat treatment and densification, the coating film may exhibit an increase in refractive index and radiation absorption without a significant loss of contrast.

[0161] Patterning by Exposure and Patterned Coating Films Coating films can be finely patterned using radiation. As described above, the composition of the coating film, depending on the composition of the resist solution, can be designed to sufficiently absorb the desired form of radiation. Absorption of radiation generates energy that breaks the bonds between the metal and the hydrocarbon groups, resulting in at least some of the hydrocarbon groups no longer being available to stabilize the material. Radiation degradation products, including hydrocarbon groups or fragments, may or may not diffuse from the film, depending on process variables and the identity of such products. Upon absorption of a sufficient amount of radiation, the exposed coating film condenses, i.e., forms an enhanced metal oxo / hydroxo network, which may include water absorbed from the ambient atmosphere. Radiation can generally be delivered according to a selected pattern. Such a radiation pattern is transferred as a latent image in the coating film, with corresponding irradiated and non-irradiated areas. The irradiated areas tend to chemically alter the components that make up the coating film. As described below, upon development, selective removal of the non-irradiated or irradiated portions of the coating film can form patterns with very sharp edges.

[0162] The radiation may typically be directed to the coated substrate through a mask, or a radiation beam may be controllably scanned across the substrate. Generally, the radiation may comprise electromagnetic radiation, an electron beam (beta radiation), or other suitable radiation. Generally, the electromagnetic radiation may have a desired wavelength or range of wavelengths, such as visible light, ultraviolet light, or X-rays. The achievable resolution for a radiation pattern generally depends on the wavelength of the radiation, with higher resolution patterns generally being achievable with shorter wavelength radiation. Therefore, it may be desirable to use ultraviolet light, X-rays, or an electron beam to achieve particularly high resolution patterns.

[0163] According to International Standard ISO 21348 (2007), incorporated herein by reference, ultraviolet radiation spans the wavelength range from 100 nm to less than 400 nm. A krypton fluoride laser can be used as a 248 nm ultraviolet source. The ultraviolet range can be subdivided in several ways under accepted standards, such as extreme ultraviolet (EUV), which is from 10 nm to less than 121 nm, and far ultraviolet (FUV), which is from 122 nm to less than 200 nm. The 193 nm line from an argon fluoride laser can be used as a radiation source in the FUV range. EUV light is used for lithography at 13.5 nm, and is generated from Xe or Sn plasma sources excited using high-energy lasers or discharge pulses. Soft x-rays can be defined as from 0.1 nm to less than 10 nm.

[0164] The amount of electromagnetic radiation can be characterized by the fluence or dose, which is the integrated radiant flux over the exposure time. Suitable radiation fluences are from about 1 to about 150 mJ / cm. 2 and in further embodiments from about 2 to about 100 mJ / cm 2 , and in further embodiments from about 3 to about 50 mJ / cm 2 A person of ordinary skill in the art will recognize that additional ranges of radiation fluence within the explicit ranges above are contemplated and are within the present disclosure.

[0165] In electron beam lithography, the electron beam typically induces secondary electrons, which typically alter the irradiated material. Resolution can be, at least in part, a function of the range of the secondary electrons within the material, where it is believed that higher resolution generally results from shorter-range secondary electrons. Based on the high resolution achievable by electron lithography using the inorganic coating materials described herein, the range of secondary electrons in inorganic materials is limited. The electron beam can be characterized by the energy of the beam, with suitable energies ranging from about 5 V to about 200 kV, and in further embodiments, from about 7.5 V to about 100 kV. The proximity-corrected beam dose at 30 kV is about 0.1 μC / cm 2~Approx. 5mC / cm 2 , and in a further embodiment, about 0.5 μC / cm 2 ~Approx. 1mC / cm 2 , and in other embodiments, about 1 μC / cm 2 ~Approx. 100μC / cm 2 A person of ordinary skill in the art will be able to calculate corresponding doses at other beam energies based on the teachings herein and will recognize that additional ranges of electron beam characteristics within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0166] Based on the design of the precursor in dry processes and the resist solution in wet processes, a large contrast in material properties exists between the irradiated and non-irradiated regions of the coating film, which have substantially unchanged hydrocarbon groups. While the contrast in dosage can be improved by a post-exposure heat treatment, in some embodiments, satisfactory results can be obtained without a post-exposure heat treatment. The post-exposure heat treatment appears to anneal the irradiated regions, increasing their condensation without significantly condensing the non-irradiated regions of the coating film due to thermal breakdown of the hydrocarbon group-metal bonds. For embodiments in which a post-exposure heat treatment is used, the post-exposure heat treatment may be carried out at a temperature of from about 45 to about 250°C, from about 50 to about 190°C in additional embodiments, and from about 60 to about 175°C in further embodiments. The post-exposure heat treatment may generally be carried out for at least about 0.1 minute, from about 0.5 to about 30 minutes in further embodiments, and from about 0.75 to about 10 minutes in additional embodiments. A person of ordinary skill in the art will recognize that additional ranges of post-exposure heat temperatures and times within the explicit ranges above are contemplated and are within the scope of the present disclosure. This high contrast in material properties further facilitates the formation of sharp lines in the pattern after development, as described in the following section. As a result, after exposure to radiation, the coating film is patterned with irradiated and non-irradiated areas.

[0167] Development and Patterned Structures: Image development involves contacting the coating film containing the latent image with a developer composition to either remove the non-irradiated portions to form a negative image or remove the irradiated portions to form a positive image. Using the precursors for dry processes and resist solutions for wet processes described herein, effective negative or positive patterning with desired resolution can be achieved using an appropriate developer, typically based on the same coating. In particular, the irradiated areas tend to at least partially condense, enhancing the properties of the components that make up the coating film, making them resistant to dissolution by organic solvents, while the non-irradiated areas tend to remain soluble in organic solvents. The irradiated areas tend to further condense due to the cleavage of hydrocarbon-tin bonds, liberating hydrocarbon groups, enhancing the metal oxide-like properties of the components that make up the coating film. Meanwhile, the non-irradiated material is less soluble in weak bases or aqueous acids due to its hydrophobic nature, lacking the release of hydrocarbon groups. Therefore, for positive patterning, an aqueous base can be used to remove the irradiated material while preserving the non-irradiated material.

[0168] Dry process precursors and wet process resist solutions containing hydrocarbon groups inherently produce relatively hydrophobic materials. Irradiation to break at least some of the organometallic bonds converts the material to a less hydrophobic, i.e., more hydrophilic, material. This change in properties provides a significant contrast between irradiated and non-irradiated areas of the coating film, thereby enabling both positive and negative patterning of the same coating film. Specifically, the irradiated areas of the coating film condense to some extent, becoming more metal oxide-rich, but the degree of condensation is generally moderate even without significant heating, and therefore the irradiated material becomes relatively insoluble in conventional developers.

[0169] For negative-tone imaging, the developer can be an organic solvent, such as the solvent used to form the resist solution. Generally, the choice of developer can be influenced by the solubility parameters of the coating film components (the chemical components of the irradiated and non-irradiated areas), as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. In particular, suitable developers include, for example, aromatic compounds (e.g., benzene, xylene, toluene), esters (e.g., propylene glycol monomethyl ester acetate, ethyl acetate, ethyl lactate, n-butyl acetate, butyrolactone), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, methanol), ketones (e.g., methyl ethyl ketone, acetone, cyclohexanone, 2-heptanone, 2-octanone), ethers (e.g., tetrahydrofuran, dioxane, anisole), and the like. Development may be carried out for from about 5 seconds to about 30 minutes, in further embodiments from about 8 seconds to about 15 minutes, and in additional embodiments from about 10 seconds to about 10 minutes. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the present disclosure.

[0170] For positive-tone imaging, the developer can generally be an aqueous acid or base solution. In some embodiments, an aqueous base solution can be used to obtain sharper images. To reduce contamination from the developer, it may be desirable to use a developer that does not contain metal atoms. Thus, quaternary ammonium hydroxide compositions, such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or combinations thereof, are desirable as developers. In general, quaternary ammonium hydroxides of particular interest are those of the formula R 4NOH (where R = methyl, ethyl, propyl, butyl, or combinations thereof). The coating materials described herein can generally be developed with the same developers currently commonly used for polymer resists, specifically tetramethylammonium hydroxide (TMAH). Commercially available TMAH is available at 2.38 wt. %, and this concentration can be used for the processes described herein. Additionally, mixed quaternary tetraalkylammonium hydroxides can be used. Generally, the developer can include from about 0.5 to about 30 wt. %, in further embodiments from about 1 to about 25 wt. %, and in other embodiments from about 1.25 to about 20 wt. % of a tetraalkylammonium hydroxide or similar quaternary ammonium hydroxide. A person of ordinary skill in the art will recognize that additional ranges of developer concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0171] In addition to the main developer composition, the developer can contain additional compositions to facilitate the development process. Suitable additives include, for example, dissolved salts having a cation selected from the group consisting of ammonium, d-block metal cations (e.g., hafnium, zirconium, lanthanum), f-block metal cations (e.g., cerium, lutetium), p-block metal cations (e.g., aluminum, tin), alkali metals (e.g., lithium, sodium, potassium), and combinations thereof, and an anion selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrate, sulfate, phosphate, silicic acid, boric acid, peroxide, butoxide, formate, oxalate, ethylenediamine-tetraacetic acid (EDTA), tungstic acid, molybdic acid, and the like, and combinations thereof. Other potentially useful additives include, for example, molecular chelating agents, such as polyamines, alcoholamines, amino acids, carboxylic acids, or combinations thereof. When optional additives are present, the developer can contain up to about 10% by weight of the additives, and in further embodiments up to about 5% by weight of the additives. A person of ordinary skill in the art will recognize that additional ranges of additive concentrations within the explicit ranges above are contemplated and are within the present disclosure. Additives can be selected to improve contrast, sensitivity, and linewidth roughness. Additives in the developer can also suppress metal oxide particle formation and precipitation.

[0172] For weaker developers, such as less concentrated aqueous developers, diluted organic developers, or compositions (where the coating has a lower development rate), a higher temperature development process can be used to increase the speed of the process. For stronger developers, the temperature of the development process can be lowered to slow down the rate of development and / or control the development kinetics. In general, the temperature of development can be adjusted between appropriate values ​​consistent with the volatility of the solvent. Furthermore, the developer containing dissolved coating film components near the developer-coating interface can be dispersed by sonication during development.

[0173] The developer can be applied to the coating film containing the latent image using any reasonable means. For example, the developer can be sprayed onto the patterned coating material. Spin coating can also be used. For automated processing, a puddle method, which involves statically pouring the developer onto the coating material, can be used. If desired, spin rinsing and / or drying can be used to complete the development process. Suitable rinsing solutions include, for example, ultrapure water, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof in the case of negative patterning, and ultrapure water in the case of positive patterning. After the image is developed, the coating film is disposed on the substrate as a patterned coating film.

[0174] Once the development step is complete, the patterned coating film may be heat treated to further condense the material and further dehydrate, densify, or remove residual developer from the material. While this heat treatment may be particularly desirable for embodiments in which the oxide coating material is incorporated into the final device, it may also be desirable to perform the heat treatment for some embodiments in which the coating film is used as a resist and ultimately removed if stabilization of the coating film is desired to facilitate further patterning. In particular, baking of the patterned coating film may be performed under conditions that result in the patterned coating film exhibiting a desired level of etch selectivity. In some embodiments, the patterned coating film may be heated to a temperature of about 100 to about 600°C, in further embodiments from about 175 to about 500°C, and in additional embodiments from about 200 to about 400°C. Heating may be performed for at least about 1 minute, in other embodiments from about 2 minutes to about 1 hour, and in further embodiments from about 2.5 minutes to about 25 minutes. Heating may be performed in air, vacuum, or an inert gas atmosphere such as Ar or N. A person of ordinary skill in the art will recognize that additional ranges of temperature and time for thermal treatment within the explicit ranges above are contemplated and are within the present disclosure. Similarly, non-thermal treatments, including blanket UV exposure or exposure to an oxidizing plasma, such as O, may be used for similar purposes.

[0175] In conventional organic resists, when the aspect ratio (height divided by width) of a structure becomes very large, the structure is prone to pattern collapse. Pattern collapse can be related to the mechanical instability of high-aspect-ratio structures, where forces associated with the processing step, such as surface tension, deform the structural elements. Low-aspect-ratio structures are more stable with respect to potential deformation forces. Using the dry process precursors and wet process resist solutions described herein, structures with thinner coating films can be effectively processed, thereby achieving improved patterning without the need for high-aspect-ratio patterned coating films. Thus, very high-resolution features were formed without relying on high-aspect-ratio features in the patterned coating films.

[0176] The resulting structures can have sharp edges and very low linewidth roughness. In particular, in addition to being able to reduce linewidth roughness, the high contrast also enables the formation of small features and spaces between features, as well as the ability to form very well-resolved two-dimensional patterns (e.g., sharp corners). Thus, in some embodiments, adjacent linear portions of adjacent structures can have an average pitch (half pitch) of about 60 nm (30 nm half pitch) or less, in some embodiments about 50 nm (25 nm half pitch) or less, and in further embodiments about 34 nm (17 nm half pitch) or less.

[0177] Pitch can be evaluated by design and confirmed by scanning electron microscopy (SEM), e.g., top-down imaging. As used herein, pitch refers to the spatial period, i.e., center-to-center distance, of repeating structural elements, and as commonly used in the art, half-pitch is half the pitch. Feature dimensions of a pattern can also be expressed in terms of the average width of the feature, typically evaluated away from corners, etc. Feature can also refer to the gaps between and / or material elements. In some embodiments, the average width can be about 25 nm or less, further embodiments about 20 nm or less, and in additional embodiments about 15 nm or less. Average linewidth roughness can be about 5 nm or less, in some embodiments about 4.5 nm or less, and further embodiments about 2.5 to about 4 nm. Linewidth roughness evaluation is performed by deriving the 3σ deviation from the average linewidth through analysis of top-down SEM images. The average contains both high-frequency and low-frequency roughness, i.e., short correlation lengths and long correlation lengths, respectively. While the linewidth roughness of organic resists is primarily characterized by a long correlation length, the organometallic coating materials of the present embodiments exhibit a significantly shorter correlation length. In the pattern transfer process, the short correlation roughness can be smoothed out during the etching process to produce a much higher fidelity pattern. A person of ordinary skill in the art will recognize that additional ranges of pitch, average width, and linewidth roughness within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0178] <Further Processing of Patterned Coating Film> After forming a patterned coating film on a substrate, the substrate can be further processed to facilitate the formation of a selected device. Furthermore, deposition of additional materials, etching, and / or patterning can typically be performed to complete the structure. The patterned coating film may or may not be ultimately removed. In either case, it is desirable to improve the quality of the patterned coating film to form improved devices (e.g., devices with a smaller footprint, etc.).

[0179] Alternatively or additionally, deposition of additional material according to a mask pattern can modify the properties of the underlying structure and / or provide contact with the underlying structure. The additional coating material can be selected based on the desired material properties. In addition, the density of the patterned inorganic coating material can provide a high implant resistance so that ions can be selectively implanted into the underlying structure through the openings in the mask. In some embodiments, the additionally deposited material can be a dielectric, semiconductor, conductor, or other suitable material. The additionally deposited material can be deposited using any suitable means, such as a solution-based procedure, chemical vapor deposition (CVD), sputtering, physical vapor deposition (PVD), or other suitable means.

[0180] Generally, multiple additional layers can be deposited. Additional patterning can be performed in conjunction with the deposition of multiple layers. If desired, any additional patterning can be performed using additional amounts of the coating materials described herein, polymer-based resists, other patterning means, or combinations thereof.

[0181] As described above, the patterned coating film may or may not be removed. If the patterned coating film is not removed, the patterned coating film is incorporated into the structure. In the embodiment in which the patterned coating film is incorporated into the structure, the properties of the patterned coating film can be selected to provide not only the desired patterning properties, but also the properties of the material within the structure.

[0182] When removal of the patterned coating film is desired, the patterned coating film functions as a conventional resist. The patterned coating film is used to pattern subsequently deposited materials and / or selectively etch the substrate through spaces within the condensed coating material before removal. The condensed coating material can be removed using an appropriate etching process. Specifically, to remove the condensed coating material, dry etching can be performed using, for example, BCl plasma, Cl plasma, HBr plasma, Ar plasma, or other suitable process gas plasma. Alternatively or additionally, wet etching can be used to remove the patterned coating material, for example, using an aqueous acid or base solution, HF (water), or buffered HF (water) / NHF, or oxalic acid.

[0183] The resist material can be utilized to perform multiple patterning. That is, the process can be applied to multiple coatings and multiple patterning. With regard to multiple patterning, a notable difference between the inorganic coating materials described herein and conventional organic resists is that the organic resists remain soluble in conventional resist casting solvents even after thermal baking. The resist materials described herein can be hardened by thermal baking, thereby becoming insoluble in organic solvents, allowing subsequent coating layers and the like to be formed on the resist material.

[0184] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0185] Unless otherwise specified, the following raw materials were used. In addition, each tin compound may be referred to as follows.

[0186] [Precursor] iPrSn(NMe2)3: isopropyltris(dimethylamido)tin, 119Sn-NMR: -64ppm... Compound (1)

[0187] [Impurity tin compounds (A2, A3, A4)] Tin compound (A2): iPrSn(NMe): diisopropyl form 119 Sn-NMR: -18 ppm...Compound (2) Tin compound (A3): Sn(NMe2)4: tetrakisamide 119 Sn-NMR: -120 ppm... Compound (3) Tin compound (A4): iPrSn(NMe2)2(NMeCHNMe2), 119 Sn-NMR: -82 ppm...Compound (4) Tin compounds other than compounds (1) to (4): Other impurities

[0188] [Organic solvent] Dehydrated hexane: n-hexane (dehydrated) (manufactured by Kanto Chemical Co., Inc.) (water content 10 ppm)

[0189] <<Preparation and Analysis of Monoalkyltin Compounds (Precursors)>> The precursors were prepared to have the compositions of the following Comparative Examples and Examples, and the detailed compositions of the functional groups in the obtained precursors are shown in Tables 2 and 3, respectively. Note that the abbreviations for the organic group R in Tables 2 and 3 are as follows: iPr: isopropyl, molecular formula C3H7 tBu: tertial-butyl, molecular formula C4H9 1Me-cPen: 1Me-cyclopentyl, molecular formula C6H 11 ・3Butenyl: 3-butenyl, molecular formula C4H7

[0190] Comparative Example 1-1 Precursor L1: RSn(NMe) purity 99.2 mol% (R=isopropyl) A monoalkyltin compound (precursor) having the composition (content of tin compounds (1) to (4)) shown in Table 1 and the following text was prepared.

[0191]

[0192] (Method for Producing Precursor L1) A 200 L light-shielded glass reactor (with a jacket using circulating water), a cooling condenser with an internal coil, a stirring device (stirring blade: Twin Star, diameter: 350 mm, width: 110 mm, made of Teflon (registered trademark)-coated stainless steel), and a 50 L glass dropping device were prepared and used. The pressure inside the reactor was reduced to 3 kPa, and then the operation of replacing the atmosphere with nitrogen was repeated three times. Hexane (36.6 kg, water content 21 ppm) and n-butyllithium [41.0 kg, 96.8 mol (3.09 eq), 15% hexane solution (containing hexane equivalent to 34.9 kg)] were charged and stirred at 150 rpm [impeller tip speed (m / s) = 3.14 × 0.35 × 150 / 60 = 2.74 (m / s)]. Dimethylamine (8.69 kg, 193.6 mol, 6.18 eq) was added dropwise over 1 hour while maintaining the temperature between -5 and 10°C. The resulting lithium dimethylamide slurry was stirred at 23 to 27°C for 1 hour.

[0193] The temperature of the obtained lithium dimethylamide slurry was adjusted to -10°C, and a hexane solution (4.20 kg in terms of hexane) containing isopropyltrichlorotin (8.40 kg, 31.3 mol, 1.00 eq) was added dropwise from a glass dropping device over 2 hours while maintaining the temperature within the temperature range (internal temperature -10°C to 0°C). Thereafter, the dropping device was washed with hexane (0.61 kg) while the solution was added dropwise.

[0194] After the dropwise addition, the temperature was raised to 25°C over 3 hours and then stirred for 16 hours. The resulting reaction solution was filtered using a pressure filter to remove the white solid (LiCl), yielding a clear filtrate. The white solid was further washed with dehydrated hexane (7.3 kg x 3), and the filtrates were combined. The resulting reaction solution was concentrated under reduced pressure. The resulting concentrated solution (10.3 kg) was loaded into a light-shielded glass simple distillation apparatus while still under a nitrogen atmosphere. The distillation apparatus was introduced under a nitrogen inert gas atmosphere, and simple distillation was carried out under reduced pressure and heating to obtain the corresponding tin compound (1) as a fraction (distillation apparatus: glass simple distillation apparatus wrapped in a light-shielding cloth; distillation conditions: internal temperature: 70-80°C, vacuum: 0.3 kPa). The tin compound (1) obtained by this simple distillation was purified by precision distillation using a distillation column with 30 theoretical plates at a reflux ratio of 10. The resulting precision distillation product of tin compound (1) was designated precursor L1.

[0195] Comparative Example 1-2 Precursor L2: RSn(NMe) purity 99.8 mol% (R=tertial-butyl)

[0196] <Comparative Example 1-3> Precursor L3: RSn(NMe2)3 purity 99.9 mol% (R = 1-methyl-cyclopentyl)

[0197] Comparative Example 1-4 Precursor L4: RSn(OtBu) purity 99.7 mol% (R=3-Butenyl)

[0198] Example 1-1 Precursor L5: Precursors L1 and L2 mixed at a mass ratio of 7:3

[0199] Example 1-2 Precursor L6: Precursors L1 and L3 mixed at a mass ratio of 7:3

[0200] Example 1-3 Precursor L7: Precursors L1 and L4 mixed at a mass ratio of 7:3

[0201]

[0202] <<Preparation and Analysis of Tin Hydrolyzate by Hydrolysis>> <Comparative Example 2-1> The mixing and hydrolysis equipment used consisted of a 100 mL glass three-neck flask (covered with aluminum foil to shield from light, washed with ultrapure water, and then dried), and a magnetic stirrer (stir bar: Teflon rod, 20 mm long). Under an inert gas (G1 grade nitrogen, manufactured by Taiyo Nippon Sanso Corporation) atmosphere and in the dark, 10 mL of dehydrated hexane (water content: 10 ppm) was added to the flask using an airtight syringe. Then, 1.0 g (3.4 mmol, calculated as iPrSn(NMe2)3) of precursor L1 was added to the flask using an airtight syringe. The resulting solution was cooled in an ice bath, and while stirring at 200 rpm, 1.0 mL of demineralized water (18.2 MΩ) was added over 3 minutes while maintaining the temperature at 0-10°C. As a result, a white solid slurry was formed. This was further stirred for 10 minutes while maintaining the temperature at 0 to 10°C. The slurry was then filtered through filter paper (Kiriyama 5B) to obtain a white solid. The solid was rinsed twice with demineralized water (18.2 MΩ) (3.0 mL) and collected in a 20 mL glass vial. The glass vial was vacuum dried at 40°C for 8 hours to obtain a white solid tin hydrolyzate H1.

[0203] The composition and crystallinity of the obtained tin hydrolysate were analyzed using the following measuring device and conditions, and the results are shown in Table 3 below. [NMR analysis device and method] NMR analysis device: Avance Neo, 600 MHz, manufactured by Bruker Corporation, probe: cryo 5 mm BBO The tin hydrolysate was dissolved in the measurement solvent shown in the examples below, and NMR ( 1 H-NMR, 13 C-NMR, 119Sn-NMR and their correlation NMR were measured. From the obtained NMR chart, the composition and purity of the tin hydrolysate were analyzed based on the above-mentioned section on composition and purity analysis of tin hydrolysates. [ESI-MS analysis equipment and method] ESI-MS analysis equipment: Xevo G2-XS Qtof, manufactured by Waters, measurement mode: ESI positive, solvent: acetonitrile Analysis method: The theoretical mass spectrum including the isotopes of each tin compound was calculated using the analysis software attached to the equipment, and the peak with the maximum intensity from the theoretical mass spectrum was detected as the peak of each tin compound, and the peak intensity was quantified. [XRD analysis equipment and method] XRD analysis equipment: X'Pert Pro MPD, manufactured by PANalytical, X-ray source: CuKα focusing optical system, scanning range: 3 to 50°, half-width analysis method: calculated by profile fitting method (Pearson-VII function, pseudo-Voigt function)

[0204] Comparative Examples 2-2 to 2-4 The same procedure as in Comparative Example 2-1 was carried out (the precursor amount was standardized to 1.0 g, and the same amounts of other reagents were used) except that the precursor in Comparative Example 2-1 was changed to precursors L2 to L4 as shown in Table 3 below, to obtain tin hydrolysates H2 to H4 shown below. The compositions and crystallinity of the obtained tin hydrolysates were analyzed, and the results are also shown in Table 3 below.

[0205] Example 2-1: The mixing and hydrolysis equipment used consisted of a 100 mL glass three-neck flask (covered with aluminum foil to shield from light, washed with ultrapure water, and then dried), and a magnetic stirrer (stir bar: Teflon rod, 20 mm long). Under an inert gas (G1 grade nitrogen, manufactured by Taiyo Nippon Sanso Corporation) atmosphere and in the dark, 10 mL of dehydrated hexane (water content: 10 ppm) was added to the flask using an airtight syringe. Then, under an inert gas atmosphere and in the dark, 0.70 g (2.38 mmol) of precursor L1 and 0.30 g (0.97 mmol) of precursor L2 were added using an airtight syringe. The resulting solution was cooled in an ice bath and stirred at 200 rpm for 5 minutes. This produced a mixture of precursors L1 and L2. (The molar ratio of precursors L1:L2 was 0.71:0.29). To this mixture, demineralized water (18.2 MΩ) (1.0 mL) was added over 3 minutes while maintaining the temperature at 0 to 10°C. As a result, a white solid slurry was formed. This was further stirred for 10 minutes while maintaining the temperature at 0 to 10°C. The slurry was then filtered using filter paper (Kiriyama 5B) to obtain a white solid. The solid was rinsed twice with demineralized water (18.2 MΩ) (3.0 mL) and collected in a 20 mL glass vial. The glass vial was vacuum dried at 40°C for 8 hours to obtain a white solid tin hydrolyzate H5.

[0206] Example 2-2: Using the same method as in Example 2-1, a mixed solution of precursors L1 and L2 was prepared using 0.70 g (2.38 mmol) of precursor L1 and 0.30 g (0.90 mmol) of precursor L2 (molar ratio of precursors L1:L2 = 0.73:0.27). Using the same procedure as in Example 2-1, tin hydrolyzate H6 was obtained.

[0207] Example 2-3: Using the same method as in Example 2-1, a mixed solution of precursors L1 and L3 was prepared using 0.70 g (2.38 mmol) of precursor L1 and 0.30 g (0.90 mmol) of precursor L3 (precursor molar ratio L1:L2 = 0.76:0.24). Using the same procedure as in Example 2-1, tin hydrolyzate H7 was obtained.

[0208]

[0209] [Analysis results of tin hydrolysate H1] (R = isopropyl, chemical formula C3H7) 119 As a result of Sn-NMR measurement, as shown in Table 3, a 1:1 peak was observed at SnNMR (MeOD): 5-coordinate (RSnO4): -337 ppm, and 6-coordinate (RSnO5): -513 ppm. This corresponds to the tin dodecamer cluster (nBuSn) reported in Organometallics 19, 2000, 1940-1949. 12 O 14 This correlates with the NMR results of (OH)6, i.e., the composition formula RSnO (3 / 2-x / 2) (OH) x A compound corresponding to the following was obtained.

[0210] As a result of the analysis of the tin hydrolyzate H1 by electrospray ionization mass spectrometry (ESI-MS), the ESI-MS chart of H1 is shown in Figure 1. In this chart, the composition formula RSnO (3 / 2-x / 2) Divalent ions (specifically, chemical formula [(C3H7Sn) 12 O 14 (OH) +2 Peaks corresponding to a singly charged ion (m / z = approximately 2268), calculated m / z = approximately 1134, and their adducts (equivalent to m / z + 40) were observed. This doubly charged ion has the chemical formula (RSn) 12 O 14 (OH)6 +2 is equivalent to

[0211] [Analysis results of tin hydrolysate H2] (R = tertial-butyl, chemical formula C4H9) 119 As a result of Sn-NMR measurement, as shown in Table 3, peaks were observed for 5-coordination:6-coordination at a ratio of about 0.9:1, and the composition formula was RSnO (3 / 2-x / 2) (OH) x The tin hydrolyzate H2 was analyzed by electrospray ionization mass spectrometry (ESI-MS), and the ESI-MS chart of H2 is shown in FIG. 2. In this chart, a compound corresponding to the composition formula RSnO (3 / 2-x / 2) Divalent ions (specifically, chemical formula [(RSn)12 O 14 (OH) +2 , calculated m / z = 1218), and peaks corresponding to singly charged ions (m / z = 2435) were observed.

[0212] [Analysis results of tin hydrolysate H3] (R = 1Methyl-cyclopentyl, chemical formula CH 11 As a result of NMR identification of the tin hydrolyzate H3, as shown in Table 3, peaks were observed in the 5-coordinate:6-coordinate coordinate system at a ratio of approximately 0.6:1, and the composition formula was RSnO (3 / 2-x / 2) (OH) x A compound corresponding to the following was obtained. 1 H NMR (600 MHz MeOD / CDCl3 1 / 1): 2.0-2.4 (m, 2H), 1.6-1.9 (m, 6H), 1.48 (Me, 3H RSnO4), 1.28 (Me, 3H RSnO5). The tin hydrolyzate H3 was analyzed by electrospray ionization mass spectrometry (ESI-MS). Figure 3 shows the ESI-MS chart of H3. This chart shows the composition formula RSnO (3 / 2-x / 2) A divalent ion (specifically, a compound corresponding to the chemical formula [R(Sn) 12 O 14 (OH) +2 , calculated m / z = approx. 1374), and peaks corresponding to singly charged ions (m / z = approx. 2747) were observed.

[0213] [Analysis Results of Tin Hydrolyzate H4] (R = 3-butenyl, Chemical Formula: C4H7) As a result of NMR identification of tin hydrolyzate H4, as shown in Table 3, peaks were observed for 5-coordinated and 6-coordinated structures at a ratio of approximately 0.4:1. (3 / 2-x / 2) (OH) x The tin hydrolyzate H4 was analyzed by electrospray ionization mass spectrometry (ESI-MS), and the ESI-MS chart of H4 is shown in FIG. 4. In this chart, a compound corresponding to the composition formula RSnO (3 / 2-x / 2) A divalent ion (specifically, a compound having the chemical formula [(RSn) 12 O 14 (OH) +2, calculated m / z = approx. 1240), and peaks corresponding to singly charged ions (m / z = approx. 2480) were observed.

[0214] [Analysis results of tin hydrolysate H5] (R A =isopropyl Chemical formula C3H7,R B = tertial-butyl (chemical formula: C4H9) As a result of NMR identification of the tin hydrolyzate H5, as shown in Table 3, peaks were observed for 5-coordination: 6-coordination at a ratio of approximately 0.84:1, and the composition formula was RSnO (3 / 2-x / 2) (OH) x A compound corresponding to the compound was obtained. In addition, since no peaks other than k1 and k2 were present with detectable intensity, the value of (k1 + k2) / (k3), which indicates purity, was 0.99 or more. 1 H-NMR, 13 From the results of C-NMR analysis, the molar composition ratio R A :R B The molar ratio of H5 was calculated to be 70 / 30. This composition correlated with the molar ratio of the mixed precursors used as raw materials. Figures 5A-C show the NMR charts of H5.

[0215] As a result of electrospray ionization mass spectrometry (ESI-MS) analysis of the tin hydrolyzate H5, the ESI-MS chart of H5 is shown in FIG. 5D. In this chart, RSnO (3 / 2-x / 2) A divalent ion (specifically, a compound having the chemical formula [(R A Sn)8(R B Sn)O 14 (OH) +2 , calculated m / z = approx. 1162), and the peaks corresponding to singly charged ions (m / z = approx. 2336) appear as the most intense peaks, which is R A = 7 isopropyl, R B = tert-butyl corresponds to a tin compound (P3AB) having five substituents. A and R B In other words, in one molecule of the tin hydrolyzate, there were peaks corresponding to compounds with different compositions, such as R A and R B It has been revealed that there exists

[0216] Table A-1 below shows the molecular weights, peak intensities, and content (%) of each tin compound of the peaks detected by ESI-MS. Ten types of tin compounds (P3AB) were detected in this tin hydrolyzate H5, and tin compounds (P3A) and (P3B) having a single organic group R were also detected. The content of each tin compound was calculated using the following formula, as described above: Content (%) of each tin compound (P3AB) = [peak intensity of each tin compound (P3AB)] / [total peak intensities of each tin compound (P3AB), (P3A), and (P3B)]

[0217] The total content (%) of each tin compound (P3AB) in this formula was 97.2%. The tin compound with the highest content (%) was R A = 7 isopropyl, R B The tin compound contained five tert-butyl groups in one molecule, and its content was 16.2%. The tin compound with the highest content was a single organic group R A This was higher than the 1.8% content of tin compounds (P3A) containing only tin.

[0218]

[0219] As shown in FIG. 5E, the organic group R A In a graph plotting the number of tin compounds on the x-axis and the content (%) on the y-axis, the distribution had a single peak, with the tin compound with the highest content (%) at the peak top (maximum point). From the molecular weight and content (%) of each tin compound, the number-average molecular weight Mn, weight-average molecular weight Mw, and molecular weight distribution Mw / Mn of tin hydrolyzate H5 were calculated as shown in Table A-2 below.

[0220]

[0221] [Analysis results of tin hydrolysate H6] (R A =isopropyl Chemical formula C3H7,R B =1-Methyl-cyclopentyl Chemical formula C6H 11As a result of NMR identification of the tin hydrolyzate H6, as shown in Table 3, peaks were observed for 5-coordinate and 6-coordinate coordinates at a ratio of approximately 1.88:1. (3 / 2-x / 2) (OH) x A compound corresponding to the following was obtained. 1 H-NMR, 13 From the results of C-NMR analysis, the molar composition ratio R A :R B The ratio was calculated to be 75 / 25. Furthermore, since no peaks other than k1 and k2 were present with detectable intensity, the value of (k1 + k2) / (k3), which indicates purity, was 0.99 or greater. This composition correlated with the molar ratio of the mixed precursors used as raw materials. Figures 6A-C show the NMR charts of H6.

[0222] As a result of electrospray ionization mass spectrometry (ESI-MS) analysis of the tin hydrolyzate H6, the ESI-MS chart of H6 is shown in FIG. 6D. In this chart, the composition formula RSnO (3 / 2-x / 2) Divalent ions (specifically, chemical formula [(R A Sn) 10 (R B Sn)O 14 (OH) +2 , calculated m / z = doubly charged ions (m / z = about 1154) and singly charged ions (m / z = about 2306) appear as the most intense peaks, which is R A = 11 isopropyl, R B = 1-Methyl-cyclopentyl corresponds to a tin compound (P3AB) having one substituent. A and R B In other words, in one molecule of the tin hydrolyzate, there are peaks corresponding to tin compounds with different compositions, such as R A and R B It has been revealed that there exists

[0223] Table B-1 below shows the molecular weight, peak intensity, and content (%) of each tin compound of the peaks detected by ESI-MS. As shown in Table B-1, 11 types of tin compounds (P3AB) were detected in this tin hydrolyzate H6, and similarly, 11 types of tin compounds (P3AB) were detected in this tin hydrolyzate H6, each containing a single organic group R A The tin compound (P3A) having the formula (I) was detected, but (P3B) was not detected. The content of each tin compound was calculated using the following formula as described above: Content (%) of each tin compound (P3AB) = [peak intensity of each tin compound (P3AB)] / [total peak intensity of tin compounds (P3AB), (P3A), and (PB)]

[0224] The total content (%) of each tin compound (P3AB) in this formula was 84.8%. The tin compound with the highest content (%) was R A = 11 isopropyl, R B The tin compound contained one 1-methyl-cyclopentyl group per molecule, and its content was 19.0%. The tin compound with the highest content was found to contain a single organic group R A This was higher than the 15.2% content of tin compounds (P3A) containing only tin.

[0225]

[0226] As shown in FIG. 6E, the organic group R A In a graph plotting the number of tin compounds on the x-axis and the content (%) on the y-axis, the distribution had a single peak, with the tin compound with the highest content (%) at the peak top (maximum point). From the peak molecular weight (Mi) and content (%) (Ni) of each tin compound, the number average molecular weight Mn, weight average molecular weight Mw, and molecular weight distribution Mw / Mn of tin hydrolyzate H6 were calculated as shown in Table B-2 below.

[0227]

[0228] [Analysis results of tin hydrolysate H7] (R A =isopropyl Chemical formula C3H7,R B= 3-Butenyl (chemical formula: C4H7) As a result of NMR identification of the tin hydrolyzate H7, as shown in Table 3, peaks were observed in the 5-coordinate:6-coordinate coordinate ratio of approximately 1.1:1, and the composition formula was RSnO (3 / 2-x / 2) (OH) x A compound corresponding to the compound was obtained. In addition, since no peaks other than k1 and k2 were present with detectable intensity, the value of (k1 + k2) / (k3), which indicates purity, was 0.99 or more. 1 H-NMR, 13 From the results of C-NMR analysis, the molar composition ratio R A :R B The molar ratio of H7 was calculated to be 78 / 22. This composition correlated with the molar ratio of the mixed precursors used as raw materials. NMR charts of H7 are shown in Figures 7A and 7B.

[0229] As a result of electrospray ionization mass spectrometry (ESI-MS) analysis of the tin hydrolyzate H7, the ESI-MS chart of H7 is shown in FIG. 7C. In this chart, the composition formula RSnO (3 / 2-x / 2) Divalent ions (specifically, chemical formula [(R A Sn) 10 (R B Sn)O 14 (OH) +2 The peaks corresponding to singly charged ions (m / z = approx. 1148, calculated value) and singly charged ions (m / z = approx. 2300) appear as the most intense peaks, and R A and R B In other words, in one molecule of the tin hydrolyzate, there were peaks corresponding to compounds with different compositions, such as R A and R B It has been revealed that there exists

[0230] <<Solubility, Filterability, and Storage Stability of Resist Solution>> The obtained tin hydrolyzate is used to prepare a solution (resist solution) in a resist solvent by the following method. The obtained resist solution is subjected to a solubility test, a filtration test, and a storage stability test, and evaluated according to the following evaluation criteria.

[0231] <Comparative Examples 3-1 to 3-4, Examples 3-1 to 3-3> Specifically, each of the tin hydrolysates H1 to H7 (0.100 g) and 4-methyl-2-pentanol (4.90 g) were weighed into a 20 mL transparent glass vial to prepare a resist solution, and the vial containing the resist solution was placed in an ultrasonic generator containing water at room temperature (23° C.), and ultrasonic waves were applied for 5 minutes to perform a dissolution operation.

[0232] Comparative Example 3-5 Instead of the resist solution of Comparative Example 3-1, a resist solution was prepared by further mixing 4.0 g of the mixed solution obtained from H1 and 1.0 g of the mixed solution obtained from H2 according to JP-T-2019-500490, and dissolving operation was again carried out by applying ultrasonic waves for 5 minutes in the same manner as in Comparative Example 3-1.

[0233] [Method for Evaluating Solubility] The solubility of a tin hydrolyzate is evaluated by comparing the turbidity (transparency) when the tin hydrolyzate is dissolved in a resist solvent at a certain concentration. Specifically, 5.0 g of a 2.0% tin hydrolyzate mixture in 4-methyl-2-pentanol, as disclosed in JP-A-2019-500490, was prepared, and the turbidity (transparency) of the resulting solution was visually confirmed by comparing it with a standard turbidity solution to evaluate the solubility of the corresponding tin hydrolyzate. Kaolin turbidity standard solutions (0° (transparent), 50°, 100°, 500°, and 1000° (white turbidity)) specified in JIS K0110 were used as the standard turbidity solutions, and the turbidity closest to that of each standard turbidity solution was evaluated using the following evaluation criteria 1 to 5. (Evaluation criteria) Turbidity rating 1: 0 degrees (transparent) Turbidity rating 2: 50 degrees Turbidity rating 3: 100 degrees Turbidity rating 4: 500 degrees Turbidity rating 5: 1000 degrees (cloudy)

[0234] [Method for Evaluating Filterability] The filterability of a tin hydrolysate is evaluated by comparing the degree of clogging of a filter using a solution in which the tin hydrolysate is dissolved at a constant concentration in a resist solvent. Specifically, 5.0 g of a mixed solution of 2.0% tin hydrolysate in 4-methyl-2-pentanol as disclosed in JP-A-2019-500490 is prepared, and the degree of clogging when the solution is filtered is evaluated according to the following evaluation criteria. Specifically, the evaluation is performed by filtering 5.0 g of the mixed solution using a 10 mL syringe while applying pressure (approximately 300 kPa) to a filter with a pore size of 0.2 μm. (Filter used: 0.2 μm, made of PTFE, effective filtration area 4.0 cm) 2 (Advantech, Disposable Membrane Filter Unit DISMIC 25HP045AN) (Evaluation criteria) - If 5.0 g of filtration was possible without clogging, it was given a "1". - If 2.0 g or more was filtered and then clogged, it was given a "2". - If 2.0 g or less was filtered and then clogged, it was given a "3".

[0235] [Method for evaluating storage stability] In the filterability test, the resist solution after filter filtration was introduced into a brown glass vial (20 mL) in the air, and the vial was closed with a lid. In this state, the resist solution was stored for one month at 20°C under light-shielded conditions. After storage, the resist solution was transferred to a transparent vial and evaluated in the same manner as in the solubility evaluation, and the result was used as an evaluation of storage stability.

[0236]

[0237] From Table 4 above, in Examples 3-1 to 3-3, multiple types of organic groups R (R A , R B It was revealed that when a precursor containing tin nitrite was used, the resulting tin hydrolyzate had high solubility and a resist solution with high storage stability was obtained.

[0238] In addition, from Comparative Examples 3-1 to 3-4, a single organic group (R A It was found that the tin hydrolysate obtained using a precursor consisting of tin stearate (only tin stearate) was highly crystalline, had low solubility, and was poor in storage stability.

[0239] Furthermore, from Comparative Example 3-5, in accordance with JP-A 2019-500490, a single organic group (R A It was found that even when multiple types of tin hydrolysates consisting of tin compounds (only tin compounds) were mixed, the solubility was low. In other words, it was not possible to obtain a highly soluble tin hydrolysate unless each tin compound molecule contained multiple types of alkyl groups.

[0240] <<Preparation of Patterned Thin Films>> <Example 4> The obtained tin hydrolysates H5 to H7 from Examples 3-1 to 3-3 were dissolved in 4-methyl-2-pentanol (5 mL) using ultrasound to a concentration of 2.0%, and the resulting solution was filtered through a 0.2 μm syringe filter to obtain a transparent resist solution containing the tin hydrolysate. A silicon wafer (Si substrate, 100 mm diameter) with an oxide surface was treated with ozone and used as a substrate for the deposition of a thin resist film. Prior to resist deposition, the surface of the Si substrate was treated with hexamethyldisilazane (HMDS) vapor. The resist solution was spin-coated onto the substrate at 2000 rpm and baked on a hot plate at 90°C for 2 minutes. The film thickness after coating and baking was approximately 22 nm as measured by an ellipsometer. The coated substrate was then irradiated with ultraviolet light (light source: xenon excimer lamp (172 nm, 7.2 eV), manufactured by Ushio Inc., light source intensity: 0.7 mW / cm). 2 The film is exposed to a pattern using a developer (developer) and the pattern is projected onto the substrate. The substrate is then immersed in 2-heptanone for 15 seconds and rinsed in the same developer for another 15 seconds to form a negative image, i.e., the unexposed portions of the film are removed, leaving only the pattern-exposed portions (patterned film).

[0241] The patterned thin film is an excellent resist material having higher sensitivity and lower LWR (roughness) than those using the tin compound of the comparative example.

[0242] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

Claims

1. A tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, wherein one molecule of the tin compound contains two or more types of the organic group R and has a Sn-O-Sn structure, and the organic group R has 1 to 30 carbon atoms.

2. The tin compound has the composition formula RSnO (3 / 2-X / 2) (OH) X 2. The tin compound according to claim 1, represented by the formula: (wherein 0≦x≦3).

3. The tin compound has the chemical formula (RSn) 12 O 14 (OH)6 +2 The tin compound according to claim 1 or 2, which is a compound containing a cation represented by the formula:

4. The tin compound according to any one of claims 1 to 3, wherein the organic group R has 3 to 10 carbon atoms.

5. A tin compound according to any one of claims 1 to 4, wherein the organic group R is a hydrocarbon group.

6. The organic group R is a hydrocarbon group, and 20 to 99 mol % of the substituents constituting the organic group R are secondary hydrocarbon groups R 2 The tin compound according to any one of claims 1 to 5, 7. The organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are tertiary hydrocarbon groups R 3 The tin compound according to any one of claims 1 to 5, 8. The organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are cyclic hydrocarbon groups R c The tin compound according to any one of claims 1 to 5, 9. The organic group R is a hydrocarbon group, and 1 to 50 mol % of the substituents constituting the organic group R are hydrocarbon groups R having an unsaturated bond. u The tin compound according to any one of claims 1 to 5, 10. The tin compound according to any one of claims 1 to 9, wherein the organic group R comprises an isopropyl group and a t-butyl group.

11. The tin compound according to any one of claims 1 to 10, wherein the organic group R comprises an isopropyl group and a methylcyclopentyl group.

12. The tin compound according to any one of claims 1 to 11, wherein the organic group R comprises a saturated hydrocarbon group.

13. The tin compound according to any one of claims 1 to 12, wherein the organic group R contains 50 mol % or more of isopropyl groups.

14. A tin composition comprising the tin compound according to any one of claims 1, 3 to 13, which has a chemical formula (R A Sn) x (R B Sn) y O 14 (OH)6 +2 A tin composition comprising three or more kinds of tin compounds (P3AB) containing a cation represented by the formula: where x is an integer of 0<x<12, y is an integer of 0<y<12, and x+y=12 is satisfied. In the composition ratio of the organic group R calculated by NMR measurement of the tin composition, the organic group that occupies the largest proportion is designated as R A The organic group that occupies the second largest proportion is R B The organic group R is the organic group R A and R B It may contain organic groups other than those mentioned above.

15. The tin composition according to claim 14, wherein the total content (%) of the tin compound (P3AB) calculated by the following formula A is 80% or more. <Formula A> The content (%) of the tin compound (P3AB) = [peak intensity of the tin compound (P3AB)] / [total peak intensity of the tin compounds (P3AB), (P3A), and (P3B)] The peak intensity refers to a peak intensity measured by ESI-MASS. The tin compound (P3A) is a single organic group R A The tin compound (P3B) refers to a tin compound containing only the organic group R B This indicates tin compounds containing only tin.

16. The content (%) of the tin compound (P3AB-1) having the largest content (%) calculated by the above formula A is a single organic group R A 16. The tin composition of claim 15, wherein the content of tin compounds (P3A) is greater than or equal to 100% by weight.

17. The content (%) of each of the tin compounds (P3AB), (P3A), and (P3B) in the tin composition is plotted on the y-axis, and the organic group R A The tin composition according to any one of claims 14 to 16, wherein, in a distribution shape of a graph in which the number of contained tin compounds is plotted on the x-axis, when the tin compound (P3AB-1) is the tin compound having the largest content, the tin compound (P3AB-1) is at the peak top (maximum point) and has a single-peak distribution structure.

18. The tin composition according to any one of claims 14 to 17, wherein the molecular weight distribution Mw / Mn value calculated from the peak molecular weight (Mi) and content (%) (Ni) of each of the tin compounds (P3AB), (P3A), and (P3B) in the tin composition is 1.00001 to 1.

05.

19. 119 The sum (k1 + k2) of the peak integral value sum (k1) of 5-coordinate Sn (-250 to -350 ppm) and the peak integral value sum (k2) of 6-coordinate Sn (-450 to -600 ppm) in Sn-NMR, 119 The tin composition according to any one of claims 14 to 18, wherein the ratio [(k1 + k2) / (k3)] of all peak integral values ​​(including k1 and k2) in the range of 1000 to -1000 ppm detected by Sn-NMR to the total value (k3) is 0.9 or more.

20. 119 The tin composition according to any one of claims 14 to 19, wherein the ratio (k1 / k2) of the sum of the peak integral values ​​(k1) of five-coordinate Sn (-250 to -350 ppm) in Sn-NMR to the sum of the peak integral values ​​(k2) of six-coordinate Sn (-450 to -600 ppm) is 0.5 to 2.

5.

21. A method for producing a tin compound having a tin atom, an organic group R, and an oxo ligand and / or a hydroxo ligand, comprising the following steps: <Step 1> Blending two or more types of precursors RSnX3(A1) (wherein X in A1 is a hydrolyzable group) having different structures of the organic group R to obtain a precursor mixture; <Step 2> Contacting the blend of the precursor mixture and an organic solvent with liquid water.

22. A method for producing a tin compound and / or a tin composition according to claim 21, comprising a step of blending 100 parts by mass or more of an organic solvent relative to 100 parts by mass of the precursor mixture.

23. A tin compound or tin composition produced by the method of claim 21 or 22.

24. A resist solution comprising the tin compound according to any one of claims 1 to 13 and / or the tin composition according to any one of claims 14 to 20 and an organic solvent.

25. A method for forming a pattern, comprising the steps of applying the resist solution according to claim 24 to a substrate, exposing the substrate to radiation, and developing the resist solution with a developer.

26. A thin film on a substrate comprising a tin compound according to any one of claims 1 to 13 and / or a tin composition according to any one of claims 14 to 20.

27. A patterned thin film on a substrate comprising a tin compound according to any one of claims 1 to 13 and / or a tin composition according to any one of claims 14 to 20.

28. A method for manufacturing a substrate, comprising the pattern formation method according to claim 25.

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