Method for producing sulfur-containing cyclic siloxane

Abstract

A sulfur-containing cyclic siloxane can be produced through a simple process even under mild conditions by means of a method for producing a sulfur-containing cyclic siloxane, the method comprising: a ring-opening step for reacting a cyclic siloxane with a dihalosilane to obtain a chain siloxane; and a recyclization step for reacting the chain siloxane with a sulfurizing agent to obtain a sulfur-containing cyclic siloxane containing a sulfur atom as an atom constituting a portion of the ring structure.

Description

Method for producing sulfur-containing cyclic siloxane

[0001] The present disclosure relates to a method for producing sulfur-containing cyclic siloxanes.

[0002] Silane compounds are used in various electronic materials, including semiconductors. In the fabrication of semiconductor devices, these compounds are utilized as raw materials for forming silicon-containing thin films, and are used to produce thin films such as silicon films, silicon oxide films, silicon nitride films, silicon carbonitride films, and silicon oxynitride films by various vapor deposition processes. For example, Patent Document 1 proposes a method for forming a uniform silicon oxide film by atomic layer deposition (ALD) using the aminosilane compound bisdiethylaminosilane (BDEAS) as a silicon source.

[0003] Among these silane compounds, synthesis examples of sulfur-containing cyclic siloxanes containing a sulfur atom as part of the ring structure have been reported in the past. For example, known methods include adding dimethyldichlorosilane to a mixture of 5-anisyl-2,2,3,3-tetramethyl-5-thio-1,4,5,2,3-dithiaphosphadigermorane and hexamethylcyclotrisiloxane to cause a reaction (Non-Patent Document 1), reacting hexamethylcyclotrisiloxane and dodecamethylcyclohexasilane with sulfur (Non-Patent Document 2), and heat-treating hexamethylcyclotrisiloxane and hexamethylcyclotrisilathiane (Non-Patent Document 3).

[0004] WO2006 / 097525

[0005] Canadian Journal of Chemistry, 1986, vol.64, p.615-620.Journal of Organometallic Chemistry, 1988, vol.346, p.287-296.Journal of Organometallic Chemistry, 1979, vol.165, p.C1, C3, C4

[0006] However, these conventionally known methods have problems such as requiring a reaction step at a high temperature of 150° C. or higher, requiring a large number of steps, etc. The present disclosure aims to provide a method that can produce sulfur-containing cyclic siloxanes using simple steps and under mild conditions.

[0007] One aspect of the present disclosure provides a production method described in the following items: [Item 1] A production method for a sulfur-containing cyclic siloxane, comprising: a ring-opening step of reacting a cyclic siloxane with a dihalosilane to obtain a linear siloxane; and a recyclization step of reacting the linear siloxane with a sulfurating agent to obtain a sulfur-containing cyclic siloxane containing a sulfur atom as an atom constituting part of the ring structure. [Item 2] The cyclic siloxane is represented by the following formula: [In the formula, R １ ~R ６ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ６ may be bonded to each other to form a ring, and n is an integer of 0 to 2.], wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms, and X is independently in each occurrence a halogen atom.], wherein the sulfiding agent is a compound represented by the following formula: Y ２ Item 3: The method according to Item 1, wherein the sulfur-containing cyclic siloxane is a compound represented by the following formula: [wherein Y, at each occurrence, is independently a hydrogen atom, a sodium atom, or a lithium atom.] [Item 4: The method according to Item 1 or 2, wherein the ring-opening step uses one or more catalysts selected from the group consisting of Lewis base compounds having a bond represented by -C(=O)N<, phosphorus compounds having a P=O bond, quaternary ammonium salts, and quaternary phosphonium salts. [Item 5: The method according to Item 1, wherein the sulfur-containing cyclic siloxane is a compound represented by the following formula: [In the formula, R １ ~R ８is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, and n is an integer of 0 to 2. [Item 5] The method according to any one of Items 1 to 3, wherein the linear siloxane is a compound represented by the following formula: [In the formula, R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, X is independently a halogen atom in each occurrence, and n is an integer of 0 to 2. [Item 6] The method according to any one of Items 1 to 4, wherein the cyclic siloxane is a compound represented by the following formula: [In the formula, R １ ~R ６ is independently in each occurrence a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 2.], wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ [Item 7] The method according to any one of Items 1 to 5, wherein the cyclic siloxane is a compound represented by the following formula: [In the formula, R １ ~R ６ is a methyl group, and n is an integer of 0 to 2.], wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ [Item 8] The method according to any one of Items 1 to 6, wherein the cyclic siloxane is a compound represented by the following formula: [In the formula, R １ ~R ６is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ６ may be bonded to each other to form a ring, and n is 0 or 1. [Item 9] The method according to any one of Items 1 to 7, wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ [Item 10] The method according to any one of Items 1 to 8, wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ [Item 11] The method according to any one of Items 1 to 9, wherein the sulfurizing agent is a compound represented by the following formula: Y ２ [Item 12] The method according to any one of Items 1 to 11, wherein the sulfur-containing cyclic siloxane is a compound represented by the formula: S [wherein Y, in each occurrence, is independently a hydrogen atom or a lithium atom.] [Item 12] The method according to any one of Items 1 to 11, wherein the sulfur-containing cyclic siloxane is a silicon-containing film precursor.

[0008] According to the production method according to one aspect of the present disclosure, sulfur-containing cyclic siloxanes can be produced by simple steps under mild conditions.

[0009] 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane obtained according to the examples of the present disclosure １ The H-NMR chart is shown below.

[0010] The method for producing the sulfur-containing cyclic siloxane of the present disclosure will be described in detail below. The method for producing the sulfur-containing cyclic siloxane of the present disclosure includes at least two steps: a ring-opening step and a recyclization step. The method for producing the sulfur-containing cyclic siloxane of the present disclosure includes a ring-opening step in which a cyclic siloxane is reacted with a dihalosilane to obtain a linear siloxane, and a recyclization step in which the linear siloxane is reacted with a sulfurizing agent to obtain a sulfur-containing cyclic siloxane containing a sulfur atom as an atom constituting part of the ring structure.

[0011] <Ring-Opening Step> In the ring-opening step, a cyclic siloxane is reacted with a dihalosilane to obtain a chain siloxane.

[0012] In the ring-opening step, it is preferable to react the cyclic siloxane with the dihalosilane in the presence of one or more catalysts selected from a Lewis base compound having a bond represented by —C(═O)N<, a phosphorus compound having a P═O bond, a quaternary ammonium salt, and a quaternary phosphonium salt to obtain a linear siloxane.

[0013] For example, in the ring-opening step, a cyclic siloxane and a dihalosilane may be reacted in the presence of a catalyst to open the ring of the cyclic siloxane and produce a linear siloxane having halogen atoms at both ends as a synthetic intermediate. For example, this step can be represented by the following reaction formula: R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, n is an integer of 0 to 2, and X, independently in each occurrence, is a halogen atom.

[0014] [Cyclic Siloxane] In the present disclosure, a cyclic siloxane is a compound in which a plurality of siloxane bonds are connected to form at least a part of a cyclic structure. In the present disclosure, a cyclic siloxane is a compound represented by the following formula: [In the formula, R １ ~R ６is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ６ may be bonded to each other to form a ring, and n is an integer of 0 to 2. The cyclic siloxane may be aliphatic or aromatic.

[0015] R １ ~R ６ The hydrocarbon group in R may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and is preferably an aliphatic hydrocarbon group. １ ~R ６ Examples of the hydrocarbon group in include alkyl groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or pentyl), alkenyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., vinyl or 2-propenyl), and alkynyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., ethynyl or propynyl).

[0016] R １ ~R ６ The hydrocarbonoxy group in R may be an aliphatic hydrocarbonoxy group or an aromatic hydrocarbonoxy group, and is preferably an aliphatic hydrocarbonoxy group. １ ~R ６ Examples of the hydrocarbonoxy group in the formula (I) include an alkoxy group having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., a methoxy group, an ethoxy group, or a propoxy group), an alkenyloxy group having 2 to 6 carbon atoms (e.g., a vinyloxy group or a 2-propenyloxy group), and an alkynyloxy group having 2 to 6 carbon atoms (e.g., a 2, 3, 4, 5, or 6) (e.g., an ethynyloxy group or a propynyloxy group).

[0017] R １ ~R ６ The average number of carbon atoms may be 0 to 6, preferably 1 to 3, and more preferably 1 or 2.

[0018] R １ ~R ６ At least one of R may be other than a hydrogen atom (the hydrocarbon group or the hydrocarbonoxy group). １ ~R ６ The number of R １ ~R ６ With respect to the total number of R, it may be 0% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, and is preferably 50% or more. １ ~R ６ may be the same.

[0019] R １ ~R ６ may be a hydrocarbon group or a hydrocarbonoxy group (especially an aliphatic group), which may be linear, branched, or cyclic, preferably linear or branched, more preferably linear.

[0020] R １ ~R ６ may all be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms (e.g., 1 to 3 carbon atoms, or 1 to 2 carbon atoms), and more preferably a methyl group.

[0021] R １ ~R ６ may or may not be bonded to each other to form a ring. When a ring is formed, one R １ ~R ６ and R bonded to, for example, the same silicon atom or adjacent silicon atoms. １ ~R ６ may form a ring, and typically R １ ~R ６ may form a ring together. Here, the bond means that R １ ~R ６ The bond possessed by each of R １ ~R ６ The bond generated by the elimination of a hydrogen atom from R １ ~R６ The structure formed by bonding each other may be a linear or branched alkylene structure, a linear or branched oxyalkylene structure, or a linear or branched dioxyalkylene structure, and may have 2 to 12, 2 to 6, or 4 to 6 carbon atoms.

[0022] n is an integer of 0 to 2, for example, 1.

[0023] The molecular weight of the cyclic siloxane may be from 100 to 1,000, and preferably from 100 to 400.

[0024] The cyclic siloxane may have 0 to 50 carbon atoms, and preferably 0 to 20 carbon atoms.

[0025] [Dihalosilane] Dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R ７ and R ８ may be bonded to each other to form a ring, and X is, independently in each occurrence, a halogen atom. The dihalosilane may be aliphatic or aromatic.

[0026] R ７ and R ８ The hydrocarbon group in R may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and is preferably an aliphatic hydrocarbon group. ７ and R ８ Examples of the hydrocarbon group in include alkyl groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or pentyl), alkenyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., vinyl or 2-propenyl), and alkynyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., ethynyl or propynyl).

[0027] R ７ and R８ The hydrocarbonoxy group in R may be an aliphatic hydrocarbonoxy group or an aromatic hydrocarbonoxy group, and is preferably an aliphatic hydrocarbonoxy group. ７ and R ８ Examples of the hydrocarbonoxy group in the formula (I) include an alkoxy group having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., a methoxy group, an ethoxy group, or a propoxy group), an alkenyloxy group having 2 to 6 carbon atoms (e.g., a vinyloxy group or a 2-propenyloxy group), and an alkynyloxy group having 2 to 6 carbon atoms (e.g., a 2, 3, 4, 5, or 6) (e.g., an ethynyloxy group or a propynyloxy group).

[0028] R ７ and R ８ The average number of carbon atoms may be 0 to 6, preferably 1 to 3, and more preferably 1 or 2.

[0029] R ７ and R ８ At least one of the groups may be other than a hydrogen atom (the hydrocarbon group or the hydrocarbonoxy group), and both of the groups may be other than a hydrogen atom.

[0030] R ７ and R ８ may be a hydrocarbon group or a hydrocarbonoxy group (especially an aliphatic group), which may be linear, branched, or cyclic, preferably linear or branched, more preferably linear.

[0031] R ７ and R ８ may all be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms (e.g., 1 to 3 carbon atoms, or 1 to 2 carbon atoms), and more preferably a methyl group.

[0032] R ７ and R ８ may or may not be bonded to each other to form a ring. ７ and R ８ The bond possessed by each of R ７ and R８ This means that the bonds formed by the removal of hydrogen atoms from the alkyl groups are bonded to each other.

[0033] X is independently in each occurrence a halogen atom, for example, a chlorine atom, a bromine atom, and an iodine atom.

[0034] The molar ratio of the cyclic siloxane to the dihalosilane is preferably 1 to 5 moles, for example 1 to 3.5 moles, and more preferably 1 to 2 moles, of dihalosilane per mole of the cyclic siloxane.

[0035] [Catalyst] The catalyst is not particularly limited as long as it can catalyze the ring-opening step, but preferably one or more catalysts selected from Lewis base compounds having a bond represented by -C(=O)N<, phosphorus compounds having a P=O bond, quaternary ammonium salts, and quaternary phosphonium salts are used. One type of catalyst may be used, or two or more types may be used in combination.

[0036] (Lewis base compound having a bond represented by -C(=O)N<) Any carboxylic acid amide compound, urethane compound, or urea compound can be used as the Lewis base compound having a bond represented by -C(=O)N<. From the viewpoint of reaction efficiency, a Lewis base compound containing a tertiary amide bond and not having an H atom directly bonded to an N atom is preferred.

[0037] Examples of the carboxylic acid amide compound include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-dimethylisobutyramide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N,N',N'-tetraacetylethylenediamine, 1-methyl-2-pyrrolidone, etc. Among these, N,N-dimethylformamide is preferred because of its easy availability.

[0038] Examples of the urethane compound include N-methoxycarbonylmaleimide, 3-methyl-2-oxazolidone, 1-ethoxycarbonyl-4-piperidone, and 1-tert-butoxycarbonylpyrrolidine.

[0039] Examples of the urea compound include tetramethylurea, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 1,1,3,3-tetraethylurea, 1,1,3,3-tetrabutylurea, N,N'-dimethyl-N,N'-diphenylurea, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyluracil, 1,3-dimethylbarbituric acid, caffeine, etc. Among these, tetramethylurea, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, and 1,3-dimethyl-2-imidazolidinone are preferred due to their ease of availability.

[0040] (Phosphorus Compound Having P═O Bond) The phosphorus compound having a P═O bond may be an inorganic phosphorus compound or an organic phosphorus compound. ３ Compounds represented by P=O, (OH) ３ Phosphoric acid represented by P=O, (OR')(OH) ２ Compounds represented by P=O, R'(OH) ２ A compound represented by P=O, (OR') ２ a compound represented by (OH)P═O, R′ ２ A compound represented by (OH)P═O, (OR′) ３ A compound represented by P=O, (OR') ２ A compound represented by R'P=O, [(OR') ２ P=O] ２ The compound represented by R', [(OH) ２ P=O] ２ R', and (OR') ２ Examples of such compounds include compounds represented by the formula HP═O (wherein R′, in each occurrence, is independently an alkyl group which may have a halogen atom as a substituent, an aryl group which may have a halogen atom as a substituent, or an alkenyl group which may have one or more substituents, and which may contain a heteroatom (for example, a nitrogen atom, an oxygen atom, or a silicon atom) in its skeleton).

[0041] R' may be a hydrocarbon group having 1 to 40 carbon atoms. The hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group, and is preferably an aliphatic hydrocarbon group. The hydrocarbon group may be branched, cyclic, or linear, and is more preferably linear.

[0042] The number of carbon atoms in R' may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more, and may be 20 or less, 15 or less, 10 or less, 5 or less, or 3 or less.

[0043] The number of heteroatoms contained in R' may be 1 to 5, for example, 1 to 3. R' may not contain any heteroatoms.

[0044] R' ３Examples of the compound represented by P═O include trimethylphosphine oxide, triethylphosphine oxide, tri-n-propylphosphine oxide, tributylphosphine oxide, tri-n-octylphosphine oxide, tris(2-ethylhexyl)phosphine oxide, tricyclohexylphosphine oxide, triphenylphosphine oxide, methyl(diphenyl)phosphine oxide, ethyldiphenylphosphine oxide, diphenylvinylphosphine oxide, ethynyl(diphenyl)phosphine oxide, methoxymethyl(diphenyl)phosphine oxide, cyclohexyldiphenylphosphine oxide, (4-bromophenyl)diphenylphosphine oxide, (3-bromophenyl)diphenylphosphine oxide, bis(4-bromophenyl)phenylphosphine oxide, and bis(3-bromophenyl) phenylphosphine oxide, tris(3-bromophenyl)phosphine oxide, tris(4-methylphenyl)phosphine oxide, 2,5-dihydroxyphenyl(diphenyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 3-methyl-1-phenyl-2-phospholene 1-oxide, [(N,N-diisobutylcarbamoyl)methyl]octylphenylphosphine oxide, 1,2-bis(diphenylphosphino)ethane monoxide, 1,3-bis(diphenylphosphino)propane monoxide, 1,8-bis(diphenylphosphinyl)naphthalene, bis[2-[(oxo)diphenylphosphino]phenyl]ether, and 2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan.

[0045] (OH) ３ The compound represented by P=O is phosphoric acid.

[0046] (OR')(OH) ２ Examples of compounds represented by P=O include methyl phosphate and phenyl phosphate.

[0047] R'(OH) ２Examples of compounds represented by P=O include methylphosphonic acid, butylphosphonic acid, vinylphosphonic acid, and phenylphosphonic acid.

[0048] (OR') ２ Examples of compounds represented by (OH)P=O include dimethyl phosphate, dibutyl phosphate, and diphenyl phosphate.

[0049] R' ２ Examples of the compound represented by (OH)P═O include dimethylphosphinic acid and diphenylphosphinic acid.

[0050] (OR') ３ Examples of compounds represented by P=O include trimethyl phosphate, tributyl phosphate, triallyl phosphate, triphenyl phosphate, and tris(trimethylsilyl) phosphate.

[0051] (OR') ２ Examples of the compound represented by R'P=O include dimethyl methylphosphonate and diethyl vinylphosphonate.

[0052] [(OR') ２ P=O] ２ An example of the compound represented by R' is tetraisopropyl methylenediphosphonate.

[0053] [(OH) ２ P=O] ２ An example of the compound represented by R' is methylenediphosphonic acid.

[0054] (OR') ２ Examples of compounds represented by HP═O include dimethyl phosphite, dibutyl phosphite, and diphenyl phosphite.

[0055] Among these, from the viewpoint of reaction efficiency, R' ３A compound represented by P═O is preferred, and in terms of reaction efficiency and easy availability, trimethylphosphine oxide, triethylphosphine oxide, tri-n-propylphosphine oxide, tributylphosphine oxide, tri-n-octylphosphine oxide, tris(2-ethylhexyl)phosphine oxide, tricyclohexylphosphine oxide, triphenylphosphine oxide, methyl(diphenyl)phosphine oxide, ethyldiphenylphosphine oxide, diphenylvinylphosphine oxide, ethynyl(diphenyl)phosphine oxide, methoxymethyl(diphenyl)phosphine oxide, or cyclohexyldiphenylphosphine oxide is more preferred.

[0056] (Quaternary Ammonium Salt, Quaternary Phosphonium Salt) As the quaternary ammonium salt and quaternary phosphonium salt, any quaternary ammonium salt and any quaternary phosphonium salt can be used.

[0057] Examples of quaternary ammonium salts include tetrabutylammonium bromide, tetrabutylammonium chloride, tetrapropylammonium bromide, methyltri-n-octylammonium chloride, etc. Examples of quaternary phosphonium salts include tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, methyltriphenylphosphonium bromide, etc. Among these, methyltri-n-octylammonium chloride or tetrabutylphosphonium bromide is preferred because of ease of availability.

[0058] The amount of the catalyst used is preferably 0.0001 to 5 moles, more preferably 0.0005 to 3 moles, and even more preferably 0.001 to 1 mole, per mole of cyclic siloxane. When the amount of catalyst used is 0.0001 mole or more, a more sufficient catalytic effect can be obtained, but when the amount exceeds 5 moles, it may be economically disadvantageous.

[0059] The reaction temperature for the ring-opening reaction is preferably −10 to 140° C., more preferably 0 to 100° C. The method and order of mixing the reaction raw materials can be appropriately determined. For example, the cyclic siloxane and catalyst may be mixed together, and then the dihalosilane may be added dropwise.

[0060] After the ring-opening reaction, a step of removing the catalyst may be carried out, for example, by distillation, filtration, decantation, or the like.

[0061] A reaction solvent may be used as needed to improve the homogeneity of the reaction system, increase the volume of the reaction system to improve stirrability, etc. The solvent may be used alone or in appropriate combination of two or more. The solvent may be appropriately selected, excluding substances that may react with cyclic siloxane and dihalosilane. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, xylene, ethylbenzene, and mesitylene; aliphatic hydrocarbon solvents such as hexane, heptane, octane, isooctane, decane, undecane, dodecane, tetradecane, hexadecane, cyclohexane, methylcyclohexane, and paraffin; hydrocarbon solvents such as industrial gasoline (rubber volatile oil, etc.), petroleum benzine, and solvent naphtha; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, methyl isobutyl ketone, diisobutyl ketone, acetonylacetone, and cyclohexanone; ester solvents such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; diethyl ether, dipropyl ether, diisopropyl ether, and dibutyl ether. ether-based solvents such as 1,2-dimethoxyethane, 1,4-dioxane, and tetrahydrofuran; solvents having an ester and an ether moiety such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, and 2-butoxyethyl acetate; siloxane-based solvents such as hexamethyldisiloxane, octamethyltrisiloxane, and dimethylsilicone oil; nitrile-based solvents such as acetonitrile; chlorinated hydrocarbon-based solvents such as methylene chloride, chloroform, and carbon tetrachloride; fluorine-modified aromatic hydrocarbon-based solvents such as m-xylene hexafluoride and benzotrifluoride; fluorine-modified ether-based solvents such as methyl perfluorobutyl ether, ethyl perfluorobutyl ether, and perfluoro(2-butyltetrahydrofuran); and dimethyl sulfoxide.

[0062] Among these, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, ketone solvents, ester solvents, nitrile solvents, fluorine-modified aromatic hydrocarbon solvents, and dimethyl sulfoxide are preferred, and toluene, hexane, heptane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, acetonitrile, m-xylene hexafluoride, and dimethyl sulfoxide are more preferred.

[0063] When the cyclic siloxane is a solid, it does not need to be dissolved uniformly in the reaction solvent, and the ring-opening reaction may be carried out in a partially dissolved state.

[0064] The amount of the solvent used is preferably 1 to 1,000 parts by mass, and more preferably 5 to 500 parts by mass, per 100 parts by mass of the total of the cyclic siloxane and dihalosilane.

[0065] The reaction pressure may be normal pressure or elevated pressure, and is preferably atmospheric pressure.

[0066] Since flammable compounds are handled, the reaction system is preferably under an inert gas atmosphere from the viewpoint of disaster prevention, such as nitrogen and argon.

[0067] The reaction time is 0.1 to 100 hours, preferably 1 to 50 hours.

[0068] <Recyclization Step> The recyclization step is a step in which the linear siloxane obtained in the ring-opening step is reacted with a sulfurizing agent to obtain a sulfur-containing cyclic siloxane.

[0069] In the recyclization step, the linear siloxane is ２ By reacting with a sulfurizing agent represented by S, a cyclic structure may be formed in the molecule to obtain a sulfur-crosslinked sulfur-containing cyclic siloxane, and for example, this process is represented by the following reaction formula: １ ~R ８ is as described above, and the above description is incorporated herein by reference.

[0070] Y in this reaction ２ The molar ratio of S to chain siloxane is 1 mole of chain siloxane to 1 mole of Y ２S may be 0.8 to 5.0 mol, preferably 0.8 to 2.0 mol, more preferably 1.0 to 1.5 mol. The reaction temperature is preferably 0 to 100°C, more preferably 10 to 40°C.

[0071] The method for mixing the reaction raw materials can be appropriately set. For example, a sulfurizing agent may be added to the chain siloxane.

[0072] In this reaction, a base may be added as necessary. Examples of the base include tertiary amines such as trimethylamine, triethylamine, diisopropylethylamine, pyridine, pyrimidine, and pyrazine. The amount of the base used is preferably 0.8 to 4.0 mol, more preferably 1.5 to 2.5 mol, per mol of the chain siloxane.

[0073] In this reaction, an organic solvent may be used as needed. The organic solvent may be added before or after the reaction. Examples of the solvent include aliphatic hydrocarbon solvents such as hexane, cyclohexane, methylcyclohexane, heptane, octane, isooctane, nonane, decane, and undecane; halogenated hydrocarbon solvents such as dichloroethane, dichloromethane, and chloroform; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, chlorobenzene, and trichlorobenzene; ether solvents such as diethyl ether, dipropyl ether, diisopropyl ether, 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran (THF), and ethylene glycol dimethyl ether; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, methyl isobutyl ketone, diisobutyl ketone, acetonylacetone, and cyclohexanone; ester solvents such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; and mixtures thereof.

[0074] Among these, aromatic hydrocarbon solvents or ether solvents are preferred, and toluene or tetrahydrofuran (THF) is more preferred. The organic solvents may be used alone or in combination of two or more.

[0075] The amount of the solvent used is preferably 10 to 5,000 parts by mass, for example 300 to 3,000 parts by mass, per 100 parts by mass of the chain siloxane.

[0076] To avoid hydrolysis of the linear siloxane and sulfur-containing cyclic siloxane, it is desirable to carry out the reaction under anhydrous conditions, with the total water content of all raw materials being 0 to 5,000 ppm by mass, preferably 0 to 500 ppm by mass, relative to the total mass of all raw materials used. It is desirable to use a dry reactor. Drying methods include heat drying, drying under reduced pressure, and inert gas substitution. Examples of inert gases include nitrogen and argon.

[0077] The reaction pressure may be normal pressure or elevated pressure, with atmospheric pressure being preferred.

[0078] In this reaction system, since flammable compounds are handled, it is desirable to operate in a closed system under an inert gas atmosphere, such as nitrogen or argon.

[0079] The reaction time is preferably 0.1 to 100 hours, more preferably 0.1 to 5 hours.

[0080] The method for extracting the sulfur-containing cyclic siloxane from the reaction solution can be appropriately selected, for example, by removing low molecular weight components such as the solvent and raw materials by distillation under reduced pressure, or by distilling the sulfur-containing cyclic siloxane.

[0081] [Chained Siloxane] In the present disclosure, the chained siloxane is a siloxane represented by the following formula: [In the formula, R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, X is independently a halogen atom in each occurrence, and n is an integer of 0 to 2. The linear siloxane may be an aliphatic or aromatic compound.

[0082] The linear siloxane can be obtained by the ring-opening process described above.１ ~R ８ is as described above, and the above description is incorporated herein by reference.

[0083] [Sulfurizing Agent] The sulfurizing agent is a compound represented by the following formula: Y ２ The compound may be represented by S .

[0084] Y is independently in each occurrence a hydrogen atom, a sodium atom, or a lithium atom. Y is preferably a hydrogen atom or a lithium atom, and more preferably a hydrogen atom.

[0085] [Sulfur-Containing Cyclic Siloxane] In the present disclosure, the sulfur-containing cyclic siloxane is a cyclic siloxane compound containing a sulfur atom as an atom constituting a part of the ring structure, and is represented by the following formula: [In the formula, R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, and n is an integer of 0 to 2. The sulfur-containing cyclic siloxane may be aliphatic or aromatic.

[0086] R １ ~R ８ The hydrocarbon group in R may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and is preferably an aliphatic hydrocarbon group. １ ~R ８ Examples of the hydrocarbon group in include alkyl groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or pentyl), alkenyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., vinyl or 2-propenyl), and alkynyl groups having 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6) (e.g., ethynyl or propynyl).

[0087] R １ ~R ８The hydrocarbonoxy group in R may be an aliphatic hydrocarbonoxy group or an aromatic hydrocarbonoxy group, and is preferably an aliphatic hydrocarbonoxy group. １ ~R ８ Examples of the hydrocarbonoxy group in the formula (I) include an alkoxy group having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6) (e.g., a methoxy group, an ethoxy group, or a propoxy group), an alkenyloxy group having 2 to 6 carbon atoms (e.g., a vinyloxy group or a 2-propenyloxy group), and an alkynyloxy group having 2 to 6 carbon atoms (e.g., a 2, 3, 4, 5, or 6) (e.g., an ethynyloxy group or a propynyloxy group).

[0088] R １ ~R ８ The average number of carbon atoms may be 0 to 6, preferably 1 to 3, and more preferably 1 or 2.

[0089] R １ ~R ８ At least one of R may be other than a hydrogen atom (the hydrocarbon group or the hydrocarbonoxy group). １ ~R ８ The number of R １ ~R ８ With respect to the total number of R, it may be 0% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, and is preferably 50% or more. １ ~R ８ may be the same.

[0090] R １ ~R ８ may be a hydrocarbon group or a hydrocarbonoxy group (especially an aliphatic group), which may be linear, branched, or cyclic, preferably linear or branched, more preferably linear.

[0091] R １ ~R ８ may all be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms (e.g., 1 to 3 carbon atoms, or 1 to 2 carbon atoms), and more preferably a methyl group.

[0092] R １ ~R ８ may or may not be bonded to each other to form a ring. When a ring is formed, one R １ ~R ８ and R bonded to, for example, the same silicon atom or adjacent silicon atoms. １ ~R ８ Here, the bond may be formed by R １ ~R ８ The bond possessed by each of R １ ~R ８ This means that the bonds formed by the removal of hydrogen atoms from the alkyl groups are bonded to each other.

[0093] n is an integer of 0 to 2, for example, 1.

[0094] The molecular weight of the sulfur-containing cyclic siloxane may be from 150 to 1,500, and is preferably from 200 to 400.

[0095] The sulfur-containing cyclic siloxane may have 0 to 60 carbon atoms, and preferably 0 to 20 carbon atoms.

[0096] Although one embodiment of the present disclosure has been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0097] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0098] [Example 1] (Ring-Opening Step) After nitrogen purge, a 1-L flask equipped with a thermometer, a condenser, and a motor stirrer was charged with hexamethylcyclotrisiloxane (249.9 g, 1.12 mol), a cyclic siloxane, tri-n-octylphosphine oxide (4.34 g, 0.011 mol), and toluene (255.4 g). Dichlorodimethylsilane (145.0 g, 1.12 mol) was added dropwise over 150 minutes while stirring at 25°C. After the dropwise addition, the mixture was stirred at 300 rpm for 3 hours while maintaining a bath temperature of 25-26°C. The toluene was then removed by simple distillation at a bath temperature of 79-134°C, an internal temperature of 69-122°C, and a reduced pressure of 3.60-240 Torr, yielding 1,7-dichloro-octamethyltetrasiloxane, a linear siloxane.

[0099] GC analysis after distillation confirmed that 335 g (83% yield) of 1,7-dichloro-octamethyltetrasiloxane was obtained with a purity of 97 area %. Similar operations were repeated several times to obtain 1,7-dichloro-octamethyltetrasiloxane for the next step.

[0100] (Recyclization Step) After nitrogen purge, 1,7-dichloro-octamethyltetrasiloxane (401.10 g, 1.050 mol), toluene (2309 g), and triethylamine (214.8 g, 2.123 mol) were added to a 10 L flask equipped with a thermometer, a condenser, and a motor stirrer. Hydrogen sulfide (36.80 g, 1.0791 mol) was bubbled into the flask over a period of 2 hours while stirring at an internal temperature of 23-24°C. After the bubble-in, the mixture was stirred for 2 hours while maintaining the internal temperature at 23°C. The solid matter was then removed by pressure filtration in a nitrogen-purged glove box. The solid matter was then washed with toluene (1132 g), and the washings and filtrate were mixed to obtain a solution containing 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane. Thereafter, toluene was removed by vacuum distillation at 30 to 180 Torr with a bath temperature of 65 to 70°C, an internal temperature of 53 to 58°C, and GC analysis confirmed that 261.8 g (80% yield) of 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was obtained with a purity of 92.4 area %.

[0101] Distillation was carried out under reduced pressure at a bath temperature of 80 to 150°C, an internal temperature of 68 to 115°C, and 3.77 to 71.8 Torr to obtain 239.3 g of 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane. GC analysis after distillation confirmed that 239.3 g (76% yield (after purification)) of 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was obtained with a purity of 98 area %. The obtained 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane (formula below) is １ Identification was carried out by H-NMR and GC-MS. １ H-NMR assignments are as follows: １ The H-NMR chart is shown in FIG. １ H-NMR (400MHz, CDCl3): δ0.12(s, 12H, [CH ３-Si]), δ0.43(s, 12H, [CH ３ -SiS])

[0102] [Example 2] (Recyclization Step) After nitrogen purge, 11.9 g (0.259 mol) of lithium sulfide and 1,902 g of tetrahydrofuran were added to a 3 L flask equipped with a thermometer, a condenser, and a motor stirrer. While stirring at room temperature (19 to 20°C), 65.3 g (0.186 mol) of 1,7-dichloro-octamethyltetrasiloxane was added dropwise over 6 minutes. After the dropwise addition, the mixture was stirred for 6 hours while maintaining the internal temperature at 20 to 26°C. Tetrahydrofuran was then removed by vacuum distillation at a bath temperature of 65°C, an internal temperature of 52 to 60°C, and a pressure of 140 to 270 Torr. The mixture was then filtered under reduced pressure in a nitrogen-purged glove box to remove solids. Thereafter, the solid was washed with 75 g of hexane, and the washing liquid and the filtrate were mixed to obtain a solution containing 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane.

[0103] Highly pure 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was obtained by vacuum distillation at a bath temperature of 70 to 95°C, an internal temperature of 60 to 86°C, and pressures of 1.89 to 397 Torr. GC analysis after distillation confirmed that 33.92 g (58% yield) of 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was obtained with a purity of 95 area % or higher. The resulting 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was １ The compound was identified as the same as in Example 1 by H-NMR and GC-MS.

[0104] According to the present disclosure, sulfur-containing cyclic siloxanes can be provided in high yield and high purity using a simple process under mild conditions. The method for producing sulfur-containing cyclic siloxanes of the present disclosure, which involves a simple process and mild conditions, reduces energy consumption and contributes to reducing carbon dioxide emissions, making it highly applicable industrially. Furthermore, the sulfur-containing cyclic siloxanes of the present disclosure can be used as silicon-containing film precursors and can be used to produce various silicon-containing films, such as silicon films, silicon oxide films, silicon nitride films, silicon carbonitride films, and silicon oxynitride films, using various deposition processes (such as atomic layer deposition (ALD) and chemical vapor deposition). These silicon-containing films function as insulating films, intermetal dielectric materials, seed layers, spacers, hard masks, trench isolation, diffusion barriers, etching stop layers, and protective layers in semiconductor devices.

Claims

1. A method for producing a sulfur-containing cyclic siloxane, comprising: a ring-opening step of reacting a cyclic siloxane with a dihalosilane to obtain a linear siloxane; and a recyclization step of reacting the linear siloxane with a sulfurating agent to obtain a sulfur-containing cyclic siloxane containing a sulfur atom as an atom constituting part of the ring structure.

2. The cyclic siloxane has the following formula: [In the formula, R １ ~R ６ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ６ may be bonded to each other to form a ring, and n is an integer of 0 to 2.], wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms, and X is independently in each occurrence a halogen atom.], wherein the sulfiding agent is a compound represented by the following formula: Y ２ S wherein Y is, independently in each occurrence, a hydrogen atom, a sodium atom, or a lithium atom.

3. The method according to claim 1, wherein the ring-opening step uses one or more catalysts selected from the group consisting of Lewis base compounds having a bond represented by -C(=O)N<, phosphorus compounds having a P=O bond, quaternary ammonium salts, and quaternary phosphonium salts.

4. The sulfur-containing cyclic siloxane is represented by the following formula: [In the formula, R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, and n is an integer of 0 to 2.

5. The chain siloxane is represented by the following formula: [In the formula, R １ ~R ８ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ８ may be bonded to each other to form a ring, X is independently in each occurrence a halogen atom, and n is an integer of 0 to 2.

6. The cyclic siloxane is represented by the following formula: [In the formula, R １ ~R ６ is independently in each occurrence a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 2.], wherein the dihalosilane is a compound represented by the following formula: [In the formula, R ７ and R ８ is independently in each occurrence a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and X is independently in each occurrence a halogen atom.

7. The cyclic siloxane is represented by the following formula: [In the formula, R １ ~R ６ is independently in each occurrence a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a hydrocarbonoxy group having 1 to 6 carbon atoms; R １ ~R ６ may be bonded to each other to form a ring, and n is 0 or 1.

8. The method of claim 1, wherein the sulfur-containing cyclic siloxane is a silicon-containing film precursor.

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