Method for producing sulfur-containing cyclic siloxane

Abstract

The present invention produces a sulfur-containing cyclic siloxane in simple steps under mild conditions by a method for producing a sulfur-containing cyclic siloxane, the method involving: a step for reacting water and a dihalosilane represented by formula (1) [in the formula, R1 and R2 are each independently a hydrogen atom, a hydrocarbon group having 1-6 carbon atoms, or a hydrocarbon oxy group having 1-6 carbon atoms at each occurrence; R1 and R2 may be bonded to each other to form a ring; and X is independently a halogen atom at each occurrence] to obtain a linear siloxane represented by formula (2) [in the formula, R1 and R2 are each independently a hydrogen atom, a hydrocarbon group having 1-6 carbon atoms, or a hydrocarbon oxy group having 1-6 carbon atoms at each occurrence; R1 and R 2 bonded to the same silicon atom may be bonded to each other to form a ring; X is independently a halogen atom at each occurrence; and n is an integer of 0-2]; and a step for reacting the linear siloxane and a sulfating agent represent by formula (3): Y2S [in the formula, Y is independently a hydrogen atom, a sodium atom, or a lithium atom at each occurrence] to obtain a sulfur-containing cyclic siloxane represented by formula (4) [in the formula, R1 and R2 are each independently a hydrogen atom, a hydrocarbon group having 1-6 carbon atoms, or a hydrocarbon oxy group having 1-6 carbon atoms at each occurrence; R1 and R2 bonded to the same silicon atom may be bonded to each other to form a ring; and n is an integer of 0-2].

Description

Method for producing sulfur-containing cyclic siloxanes

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

[0002] Silane compounds are used in a variety of electrical equipment material applications, 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 through 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 / 097525Canadian Journal of Chemistry, 1986, vol. 64, p. 615 - 620.Journal of Organometallic Chemistry, 1988, vol. 346, p. 287 - 296Journal of Organometallic Chemistry, 1979, vol. 165, p. C1, C3, C4

[0005] However, these conventionally known methods have problems such as requiring a reaction step at a high temperature of 150° C. or higher, or requiring a large number of steps. An object of the present disclosure is to provide a method for producing a sulfur-containing cyclic siloxane using simple steps under mild conditions.

[0006] One aspect of the present disclosure provides a production method described in the following items. [Item 1] Formula (1): [In the formula, R １ and R ２ 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 and R ２ may be bonded to each other to form a ring, and X is independently a halogen atom in each occurrence.] is reacted with water to produce a dihalosilane represented by formula (2): [In the formula, R １ and R ２ 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 R bonded to the same silicon atom １ and R ２ 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.], and reacting the linear siloxane with a compound represented by formula (3): Y ２ S, wherein Y is independently a hydrogen atom, a sodium atom, or a lithium atom in each occurrence, to form a sulfurizing agent represented by formula (4): [In the formula, R １ and R ２ 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 R bonded to the same silicon atom １ and R ２ may bond with each other to form a ring, and n is an integer of 0 to 2.]. [Item 2] A method for producing a sulfur-containing cyclic siloxane, comprising: １ and R ２[Item 3] The method according to Item 1, wherein R is independently in each occurrence a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. １ and R ２ is independently in each occurrence a hydrogen atom or a methyl group. [Item 4] The method of any one of Items 1 to 3, wherein n is 0 or 1. [Item 5] The method of any one of Items 1 to 4, wherein X is a chlorine atom. [Item 6] The method of any one of Items 1 to 5, wherein the sulfur-containing cyclic siloxane is a silicon-containing film precursor.

[0007] 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.

[0008] 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.

[0009] The method for producing the sulfur-containing cyclic siloxane of the present disclosure will be described in detail below.

[0010] The present disclosure has two steps (hereinafter referred to as Step I and Step II, respectively): <Step I: Hydrolysis Step> Step I is a step in which dihalosilane is reacted with water to obtain a linear siloxane by hydrolysis.

[0011] The reaction in step I will be described in more detail. Step I is a step in which dihalosilane is reacted with water to produce a linear siloxane having halogen atoms at both ends, which is a synthetic intermediate, and is represented by reaction formula [I]: [wherein, X, R １ , R ２ and n is as defined below.]

[0012] [Dihalosilane] The dihalosilane in the present disclosure is represented by the formula (1): [In the formula, R １ and R ２ 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; R１ and R ２ 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.

[0013] The dihalosilanes may be used alone or in combination of two or more.

[0014] R １ and R ２ The hydrocarbon group in R may be an aliphatic group or an aromatic group, and is preferably an aliphatic group. １ and R ２ 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).

[0015] R １ and R ２ The hydrocarbonoxy group in R may be an aliphatic group or an aromatic group, and is preferably an aliphatic group. １ and R ２ 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).

[0016] R １ and R ２ The average number of carbon atoms may be 0 to 6, preferably 1 to 3, and more preferably 1 or 2.

[0017] R１ and R ２ may be linear, branched, or cyclic, is preferably linear or branched, and is more preferably linear.

[0018] R bonded to the same silicon atom １ and R ２ may or may not be bonded to each other to form a ring. １ and R ２ The bond possessed by each of R １ and R ２ This means that the bonds formed by the removal of hydrogen atoms from the alkyl groups are bonded to each other.

[0019] R １ and R ２ At least one of R may be other than a hydrogen atom (the hydrocarbon group or the hydrocarbonoxy group). １ and R ２ All of R may be other than a hydrogen atom. １ and R ２ The number of R １ and R ２ It may be 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, based on the total number of

[0020] R １ and R ２ may be the same or different, and are preferably the same. １ and R ２ is more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

[0021] X is a halogen atom, for example, a chlorine atom, a bromine atom, or an iodine atom.

[0022] [Linear Siloxane] The linear siloxane in the present disclosure is represented by formula (2): [In the formula, R １ and R ２is 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 R bonded to the same silicon atom １ and R ２ 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. １ , R ２ For X, the explanation for dihalosilanes is used.

[0023] n is an integer of 0 to 2, preferably 0 to 1, and particularly preferably 1.

[0024] The molecular weight of the linear siloxane is 150 to 1,500, and preferably 200 to 400.

[0025] The linear siloxane may have 0 to 60 carbon atoms, preferably 0 to 20 carbon atoms.

[0026] [Reaction Conditions, etc.] The molar ratio of dihalosilane to water in this reaction is generally 0.2 to 1.5 moles, preferably 0.5 to 1.0 moles, of water per 1.0 mole of dihalosilane represented by formula (1).

[0027] The reaction temperature of this reaction may be −10 to 80° C., preferably 0 to 40° C. A reaction temperature of −10° C. or higher is preferred from the viewpoints of reactivity and workability.

[0028] The reaction time for this reaction is 0.1 to 100 hours, preferably 1 to 30 hours.

[0029] A solvent may be used in this reaction. Examples of the solvent that can be used include halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, and chloroform; aromatic hydrocarbon solvents such as benzene, toluene, xylene, 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 methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; and mixtures thereof.

[0030] Among these, ether solvents such as diethyl ether and tetrahydrofuran (THF) are preferred, with tetrahydrofuran (THF) being more preferred.

[0031] The amount of the solvent used may be 1 to 1,000 parts by mass, preferably 5 to 500 parts by mass, and more preferably 50 to 400 parts by mass, per 100 parts by mass of the total of the dihalosilane and water.

[0032] The linear siloxane can be isolated from the reaction solution by vacuum distillation after removing low molecular weight components such as the solvent and raw materials.

[0033] 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, and more preferably 0.8 to 2.0 mol, per 1.0 mol of dihalosilane.

[0034] A base may be added at the end of the reaction.

[0035] <Step II: Cyclization Step> Step II is a step in which the linear siloxane obtained in step I is reacted with a sulfurizing agent to obtain a sulfur-containing cyclic siloxane.

[0036] The reaction in step II will be described in more detail. This is a step in which the linear siloxane obtained by the reaction represented by the above-mentioned reaction formula [I] is reacted with a sulfurizing agent to form a cyclic structure within the molecule, thereby obtaining a sulfur-containing cyclic siloxane crosslinked with sulfur, as shown in reaction formula [II]: [In the formula, X, Y, R １ , R ２ and n is as defined above or below.]

[0037] [Sulfurizing Agent] The sulfurizing agent of the present disclosure is a sulfurizing agent represented by the formula (3): Y ２ S wherein Y in each occurrence is independently a hydrogen atom, a sodium atom, or a lithium atom.

[0038] Y is preferably a hydrogen atom or a lithium atom, and more preferably a hydrogen atom.

[0039] [Sulfur-containing cyclic siloxane] The sulfur-containing cyclic siloxane of the present disclosure is represented by formula (4): [In the formula, R １ and R ２ 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 R bonded to the same silicon atom １ and R ２ may be bonded to each other to form a ring, and n is an integer of 0 to 2.

[0040] R １ and R ２ The hydrocarbon group in R may be an aliphatic group or an aromatic group, and is preferably an aliphatic group. １ and R ２Examples 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).

[0041] R １ and R ２ The hydrocarbonoxy group in R may be an aliphatic group or an aromatic group, and is preferably an aliphatic group. １ and R ２ 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).

[0042] R １ and R ２ The average number of carbon atoms may be 0 to 6, preferably 1 to 3, and more preferably 1 or 2.

[0043] R １ and R ２ may be linear, branched, or cyclic, is preferably linear or branched, and is more preferably linear.

[0044] R bonded to the same silicon atom １ and R ２ may or may not be bonded to each other to form a ring. １ and R ２ The bond possessed by each of R １ and R ２The bond generated by the elimination of a hydrogen atom from R １ and R ２ The structure formed by bonding together 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.

[0045] R １ and R ２ At least one of R may be other than a hydrogen atom (the hydrocarbon group or the hydrocarbonoxy group). １ and R ２ All of R may be other than a hydrogen atom. １ and R ２ The number of R １ and R ２ It may be 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, based on the total number of

[0046] R １ and R ２ may be the same or different, and are preferably the same. １ and R ２ is more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

[0047] n is an integer of 0 to 2, preferably 0 to 1, and particularly preferably 1.

[0048] The molecular weight of the sulfur-containing cyclic siloxane is 150 to 1,500, preferably 200 to 600, and more preferably 200 to 400.

[0049] The sulfur-containing cyclic siloxane may have 0 to 60 carbon atoms, and preferably 0 to 20 carbon atoms.

[0050] [Reaction Conditions, etc.] The amount of sulfurizing agent used in this reaction may be 0.8 to 5.0 mol, preferably 0.8 to 2.0 mol, and more preferably 1.0 to 1.5 mol, per 1.0 mol of linear siloxane. The reaction temperature is preferably 0 to 100°C, and more preferably 10 to 40°C.

[0051] The reaction raw materials can be mixed by dissolving the linear siloxane in an organic solvent and then adding the sulfurizing agent, or by dissolving the sulfurizing agent in an organic solvent and then adding the linear siloxane. When Y in the sulfurizing agent is a hydrogen atom, the sulfurizing agent is preferably added to the linear siloxane.

[0052] 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, and more preferably 1.5 to 2.5 mol, per 1.0 mol of the linear siloxane.

[0053] In this reaction, a solvent may be used as needed. The solvent may be mixed with the reaction raw materials or may be added 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 methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; and mixtures thereof.

[0054] Among these, aromatic hydrocarbon solvents or ether solvents are preferred, and toluene or tetrahydrofuran (THF) is more preferred. The solvents may be used alone or in combination of two or more.

[0055] The amount of the solvent used may be 10 to 5,000 parts by mass, preferably 100 to 5,000 parts by mass, and more preferably 500 to 3,500 parts by mass, per 100 parts by mass of the linear siloxane.

[0056] In this reaction, if a solid is present in the reaction solution, filtration may be performed after completion of the reaction, if necessary. When filtration is performed, it is desirable to perform it under an atmosphere of dry inert gas to suppress decomposition of the sulfur-containing cyclic siloxane. Specific examples of inert gas include nitrogen and argon. The filtration temperature is not uniquely determined, but can be applied from 10°C to the boiling point of the solvent used, and is preferably 10 to 40°C.

[0057] In this reaction, in order to handle flammable compounds, it is desirable to carry out the reaction in a closed system under an inert gas atmosphere, examples of which include nitrogen and argon.

[0058] The reaction time may be 0.1 to 100 hours, preferably 1 to 5 hours.

[0059] Methods for extracting the sulfur-containing cyclic siloxane from the reaction solution include removing low molecular weight components such as the solvent and raw materials by distillation under reduced pressure, and distilling the sulfur-containing cyclic siloxane.

[0060] In order to avoid hydrolysis of the linear siloxane, it is desirable to carry out this reaction under anhydrous conditions. The reaction is carried out by adjusting the total water content of all raw materials to be 0 to 5,000 ppm by mass, preferably 0 to 500 ppm by mass, based on the total mass of all raw materials used.

[0061] It is desirable to use a dry reaction apparatus. Drying methods include heat drying, vacuum drying, and inert gas substitution using nitrogen, argon, etc.

[0062] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0063] Example 1: Synthesis using hydrogen sulfide [Step I] After nitrogen purge, dichlorodimethylsilane (252.5 g, 1.956 mol) and THF (250.95 g) were added to a 1000 mL flask equipped with a thermometer, a condenser, and a motor stirrer. Water (21.16 g, 1.176 mol) was then added dropwise over 90 minutes. After the addition, the mixture was stirred for 4 hours while maintaining the internal temperature at 26°C. The bath temperature was then cooled to 1°C, and triethylamine (125.76 g, 1.243 mol) was added dropwise over 45 minutes while maintaining the internal temperature at 1-5°C. After a 90-minute hold, triethylamine (43.43 g, 0.4292 mol) was added dropwise over 15 minutes. After a 19-minute hold, triethylamine (43.20 g, 0.4269 mol) was added dropwise over 15 minutes, followed by a 30-minute hold. Subsequently, 200 g of THF was added, and the solid matter was removed by vacuum filtration in a nitrogen-purged glove box. Furthermore, the solid matter was washed with 300 g of THF, and the washings and filtrate were mixed to obtain a solution containing 1,7-dichloro-octamethyltetrasiloxane. The THF was then removed by vacuum distillation at a bath temperature of 70°C, an internal temperature of 46 to 66°C, and a vacuum level of 62.5 to 760 Torr, yielding 1,7-dichloro-octamethyltetrasiloxane.

[0064] After concentration, the solids were removed by vacuum filtration in a nitrogen-purged glove box. GC analysis after filtration confirmed that 169.63 g (13.9% yield) of 1,7-dichloro-octamethyltetrasiloxane with a purity of 18.2 area% had been obtained. This was then vacuum distilled at a bath temperature of 80 to 120°C, an internal temperature of 70 to 104°C, and a reduced pressure of 1.46 to 22.8 Torr, yielding 20.8 g of 1,7-dichloro-octamethyltetrasiloxane with a purity of 80 area% or more (8.07% yield). Similar operations were repeated multiple times to obtain 1,7-dichloro-octamethyltetrasiloxane for the next step.

[0065] [Step II] After purging with nitrogen, 1,7-dichloro-octamethyltetrasiloxane (79.99 g, 0.223 mol), toluene (452.34 g), and triethylamine (50.75 g, 0.502 mol) were added to another 1000 mL flask equipped with a thermometer, a condenser, and a motor stirrer. Hydrogen sulfide (8.37 g, 0.2453 mol) was bubbled into the flask over two hours with stirring at an internal temperature of 42°C. After the bubble-in, the flask was stirred for one hour while maintaining the internal temperature at 40 to 41°C. Thereafter, the solid matter was removed by pressure filtration in a nitrogen-substituted glove box. The solid matter was washed with a solution containing toluene (145 g) and triethylamine (7.3 g). The washing liquid and the filtrate were mixed to obtain 616.2 g of a solution containing 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane. The same operation was repeated twice. A total of three operations yielded 1,569 g of 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane. The toluene was then removed by vacuum distillation at a bath temperature of 80°C, an internal temperature of 61 to 72°C, and a vacuum of 211 to 307 Torr. Thereafter, distillation was carried out under reduced pressure at a bath temperature of 100 to 115°C, an internal temperature of 80 to 100°C, and a vacuum of 1.21 to 688 Torr to obtain 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane with high purity.

[0066] GC analysis after distillation confirmed that 119.4 g (64.1% 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 98 area % or more. 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. １H-NMR (400MHz, CDCl3): δ0.12(s, 12H, [CH ３ -Si]), δ0.43(s, 12H, [CH ３ -SiS])

[0067] Example 2: Synthesis using lithium sulfide

[0068] [Step II] After nitrogen purge, 11.09 g (0.241 mol) of lithium sulfide and 1,762 g of tetrahydrofuran were added to a 3,000 mL flask equipped with a thermometer, a condenser, and a motor stirrer. While stirring at room temperature (23.5 to 24°C), 58.29 g (0.1658 mol) of 1,7-dichloro-octamethyltetrasiloxane was added dropwise over 8 minutes. After completion of the dropwise addition, the mixture was stirred for 6 hours while maintaining the internal temperature at 22 to 23°C, and then an additional 0.71 g (0.015 mol) of lithium sulfide was added, followed by stirring for an additional 90 minutes. The tetrahydrofuran was then removed by vacuum distillation at a bath temperature of 70°C and an internal temperature of 49 to 58°C. The solid matter was removed by gravity filtration in a nitrogen-substituted glove box, and a solution containing 2,2,4,4,6,6,8,8-octamethyl-1,3,5-trioxa-7-thia-2,4,6,8-tetrasilacyclooctane was obtained as the filtrate.

[0069] 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 120°C, an internal temperature of 55 to 104°C, and pressures of 4.06 to 760 Torr. GC analysis after distillation confirmed that 40.8 g (78% 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 99 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.

[0070] According to the present disclosure, sulfur-containing cyclic siloxanes can be produced using a simple process and under mild conditions. The method for producing sulfur-containing cyclic siloxanes of the present disclosure uses a simple process and mild conditions, thereby reducing energy consumption and contributing to a reduction in carbon dioxide emissions, making it highly applicable industrially. Furthermore, the sulfur-containing cyclic siloxanes of the present disclosure can be used as silicon-containing thin 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, by 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, protective layers, and the like in semiconductor devices.

Claims

1. Formula (1): [In the formula, R １ and R ２ 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 and R ２ may be bonded to each other to form a ring, and X is independently a halogen atom in each occurrence.] is reacted with water to produce a dihalosilane represented by formula (2): [In the formula, R １ and R ２ 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 R bonded to the same silicon atom １ and R ２ 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.], and reacting the linear siloxane with a compound represented by formula (3): Y ２ S, wherein Y is independently a hydrogen atom, a sodium atom, or a lithium atom in each occurrence, to form a sulfurizing agent represented by formula (4): [In the formula, R １ and R ２ 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 R bonded to the same silicon atom １ and R ２ may be bonded to each other to form a ring, and n is an integer of 0 to 2.

2. R １ and R ２ The method of claim 1, wherein, in each occurrence, is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

3. R １ and R ２ 3. The method of claim 1, wherein, in each occurrence, is independently a hydrogen atom or a methyl group.

4. The method of claim 1 or 2, wherein n is 0 or 1.

5. The method according to claim 1 or 2, wherein X is a chlorine atom.

6. The method of claim 1 or 2, wherein the sulfur-containing cyclic siloxane is a silicon-containing film precursor.

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