Sulfur-containing siloxane, composition for forming silicon-containing film comprising said sulfur-containing siloxane, sulfur-containing siloxane production method, silicon-containing film, and silicon-containing film production method

Abstract

The present invention provides a sulfur-containing siloxane represented by formula (1) [in formula (1): A1-10, in each appearance, are each independently a hydrogen atom, an organic group, a halogen, a siloxy group represented by OSiRaRbRc, or an amino group represented by NRdRe, provided A1 and A3 may be a single oxygen atom and may form a cyclic siloxane, and A4 and A6 may be a single oxygen atom and may form a cyclic siloxane; Ra-e, in each appearance, are each independently a hydrogen atom or organic group, and Rd and Re may bind to each other to form a ring; and p and q are each independently an integer 1-5].

Description

Sulfur-containing siloxane, composition for forming silicon-containing film containing the sulfur-containing siloxane, method for producing sulfur-containing siloxane, silicon-containing film, and method for producing silicon-containing film

[0001] The technical field of this disclosure relates to sulfur-containing siloxanes and compositions for forming silicon-containing films that include such compounds.

[0002] In the fabrication of semiconductor devices, silicon-containing thin films are fabricated into various forms, such as silicon films, silicon oxide films, silicon nitride films, silicon carbonitride films, and silicon oxynitride films, using various deposition processes, and are used in a variety of fields. Among these, silicon oxide films and silicon nitride films have excellent barrier properties and oxidation resistance, and therefore function as insulating films, intermetal dielectric materials, seed layers, spacers, hard masks, trench isolation, diffusion barriers, etch stop layers, and passivation layers in device fabrication.

[0003] In recent years, with the miniaturization of devices, increasing aspect ratios, and diversification of device materials, there has been a demand for film formation techniques using atomic layer deposition (ALD), which can form uniform films. Furthermore, there has been a demand in recent years for high-quality films with few impurities and excellent electrical properties. As one solution for forming high-quality films, a method of forming films at high temperatures of 500°C or higher has attracted attention. However, conventional film formation materials often decompose at high temperatures, making film formation by atomic layer deposition (ALD) difficult. Decomposition makes it difficult to self-control film formation, making it difficult to form uniform films, and this may prevent the formation of high-aspect ratio films associated with miniaturization. Therefore, there is a demand for materials that can be formed by ALD without decomposing even under high-temperature conditions.

[0004] As an example of a conventional film-forming material, Patent Document 1 proposes a method for forming a uniform silicon oxide film by atomic layer deposition (ALD) using bisdiethylaminosilane (BDEAS), an aminosilane compound, as a silicon source.

[0005] Patent Document 2 proposes a method for forming a uniform silicon oxide film at a high deposition rate by atomic layer deposition (ALD) using an aminosilane compound, 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane, as a silicon source.

[0006] Furthermore, Patent Document 3 proposes a method for forming a uniform silicon oxide film at high temperature by atomic layer deposition (ALD) using dimethylaminotrimethylsilane (DMATMS), an aminosilane compound, as a silicon source.

[0007] Patent Publication No. 2008-533731, Patent Publication No. 2018-154615, Patent Publication No. 2020-038978

[0008] However, while bisdiethylaminosilane described in Patent Document 1 and 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane described in Patent Document 2 can form silicon oxide films by ALD at temperatures of 200 to 400° C., and 100 to 300° C., respectively, these temperature ranges are low, and there is a risk that the film-forming materials will decompose and a uniform film will not be formed if the film is formed at a high temperature of 500° C. or higher. Also, dimethylaminotrimethylsilane described in Patent Document 3 can form silicon oxide films by ALD at temperatures of 500 to 650° C., which are higher than the bisdiethylaminosilane described in Patent Document 1 and the 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane described in Patent Document 2, but the high-temperature conditions are still not sufficient, and the film formation rate is slow, at approximately 0.12 nm / cycle, which raises concerns about production costs.

[0009] The present disclosure has been made under these circumstances, and a main object of the present disclosure is to provide a novel silicon precursor that can be used to form a silicon-containing film by atomic layer deposition (ALD) even under high temperature conditions.

[0010] While aminosilane compounds in which an amino group is bonded to a Si atom have traditionally been used as precursors for forming silicon-containing films, the present inventors have conducted extensive research and found that the use of thiosilane compounds in which a sulfur atom is bonded to a Si atom as a silicon-containing film precursor is effective in achieving the desired effects. In particular, the present inventors have found that using a specific compound in which a sulfur atom is bonded to a Si atom of a siloxane structure (-Si-O-Si-) as a silicon precursor enables film formation by atomic layer deposition (ALD) over a wide temperature range, including high temperature conditions, and have completed the present disclosure.

[0011] An example of an embodiment of the present disclosure is as follows.

[0012] [Term 1] Below formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a siloxane ring, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; and p and q are each independently an integer of 1 to 5.] [Item 2] A １ and A ３ are taken together as oxygen atoms to form a cyclic siloxane, and A ４ and A ６ [Item 3] The sulfur-containing siloxane according to item 1, wherein together with an oxygen atom, the group represents a cyclic siloxane. [In formula (2), R １～３are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms in each occurrence; and n and m are each independently an integer of 1 to 4. [Item 4] The sulfur-containing siloxane according to any one of Items 1 to 3, having a molecular weight of 1,000 or less. [Item 5] The sulfur-containing siloxane according to any one of Items 1 to 4, having a carbon number of 50 or less. [Item 6] The sulfur-containing siloxane according to the following formula (3): [In formula (3), R １～３ [Item 7] The sulfur-containing siloxane according to any one of items 1 to 5, which is represented by the following formula (4): [Item 8] The sulfur-containing siloxane according to any one of items 1 to 6, which is bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide represented by the following formula (5): [In formula (5), R １～３ [Item 9] The sulfur-containing siloxane according to any one of items 1 to 7, represented by the following formula (6): [In formula (6), R １～３ [Item 10] The sulfur-containing siloxane according to any one of items 1 to 8, which is represented by the following formula (7): The sulfur-containing siloxane according to any one of Items 1 to 9, which is bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide represented by the formula: [Item 11] A precursor for a silicon-containing film, comprising the sulfur-containing siloxane according to any one of Items 1 to 10. [Item 12] The precursor according to Item 11, wherein the silicon-containing film is formed by chemical vapor deposition. [Item 13] The precursor according to Item 11 or 12, wherein the silicon-containing film is formed by atomic layer deposition. [Item 14] A composition for forming a silicon-containing film, comprising the sulfur-containing siloxane according to any one of Items 1 to 10. [Item 15] The composition according to Item 14, wherein the silicon-containing film is formed by chemical vapor deposition. [Item 16] The composition according to Item 14 or 15, wherein the silicon-containing film is formed by atomic layer deposition. [Item 17] A compound represented by the formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; and p and q are each independently an integer of 1 to 5.] A method for producing a sulfur-containing siloxane represented by the formula (8-3): The method comprises: (a) a step of synthesizing the sulfur-containing siloxane from a raw material siloxane; and (b) a distillation step of isolating the sulfur-containing siloxane by distillation. [Item 18] A method for producing a sulfur-containing siloxane according to Item 17, wherein in step (a), the raw material siloxane is reacted with a sulfurizing agent to synthesize the sulfur-containing siloxane. [Item 19] The method for producing a sulfur-containing siloxane according to the formula (8-3): [In formula (8-3), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms in each occurrence; Z is a halogen or a hydrogen atom; and n is an integer of 1 to 4.] or a compound represented by the following formula (8-4): [In formula (8-4), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, Z is a halogen or a hydrogen atom, and p is an integer of 1 to 5. [Item 20] A method for producing a sulfur-containing siloxane according to Item 17 or 18, which is a compound represented by the following formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; and p and q are each independently an integer of 1 to 5.

[0013] According to the present disclosure, by using a siloxane compound having a sulfur atom as a silicon precursor, it is possible to form a uniform, high-quality film by the ALD method over a wide temperature range, including high-temperature conditions. Therefore, the method of the present disclosure enables the formation of a uniform film with excellent film properties even under high-temperature conditions, thereby enabling the fabrication of high-performance semiconductor devices.

[0014] Bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide obtained by the production method in Example 1 of the present disclosure１ 1 shows a H-NMR chart; 2 shows the relationship between the substrate temperature and the deposition rate in Examples 2 and 4 of the present disclosure and Comparative Examples 1, 2, and 3; 3 shows the relationship between the substrate temperature and the deposition rate in Examples 2 and 4 of the present disclosure and Comparative Examples 1, 2, and 3; and 4 shows the relationship between the substrate temperature and the deposition rate in Examples 2 and 4 of the present disclosure and Comparative Examples 1, 2, and 3 of the present disclosure. １ The H-NMR chart is shown below.

[0015] <Sulfur-containing siloxane> The sulfur-containing siloxane in the present disclosure is represented by the following formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; and p and q are each independently an integer of 1 to 5. The sulfur-containing siloxane of the present disclosure may be a sulfur-containing siloxane represented by the formula (1): １～７ and A １０ is a methyl group and A ８ and A ９ Compounds in which is a trimethylsiloxy group and p and q are 1 may not be included.

[0016] A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by the formula: １ and A ３may be taken together as an oxygen atom to form a cyclic siloxane (i.e., -A １ -A ３ - may be -O-), A ４ and A ６ may be taken together as an oxygen atom to form a cyclic siloxane (i.e., -A ４ -A ６ - may be -O-). １ and A ３ and A ４ and A ６ Either one of them may form a cyclic siloxane.

[0017] All A's １～１０ The ratio of the number of groups other than hydrogen atoms (e.g., organic groups, particularly monovalent aliphatic hydrocarbon groups) among all A may be 0% or more, 10% or more, 30% or more, 50% or more, or 70% or more, for example, 50% or more, for example, 100%. １～１０ The ratio of the number of groups other than hydrogen atoms (for example, organic groups, particularly monovalent aliphatic hydrocarbon groups) among these may be 90% or less, 70% or less, 50% or less, 30% or less, or 0. Each —Si may have 0 or at least 1 (1, 2, or 3) group other than hydrogen atoms (for example, organic groups, particularly monovalent aliphatic hydrocarbon groups).

[0018] All A's １～１０ At least one (e.g., one or more, two or more) of the -SiA ２ A １０ A in O- ２ and A １０ At least one (e.g., one or both) of may be a hydrogen atom, and each -SiA ５ A ７ A in O- ５ and A ７ At least one (e.g., one or both) of the groups may be a hydrogen atom. For example, each Si may be bonded to at least one hydrogen atom.

[0019] A ２ and A １０ may be the same or different from each other, and A ５ and A ７may be the same or different from each other. １～１０ may be the same or different from each other. ２ , A ５ and A ７～１０ may be the same or different from each other.

[0020] A １～１０ The organic group in A may be an aliphatic group or an aromatic group, and is preferably an aliphatic group (e.g., an aliphatic hydrocarbon group). １～１０ The organic group in A may be a heteroatom-containing group or a hydrocarbon group, and is preferably a hydrocarbon group (e.g., an aliphatic hydrocarbon group). １～１０ The organic group of A may be linear, branched, or cyclic, and is preferably linear. １～１０ The number of carbon atoms in the organic group may be 1 or more, 2 or more, 3 or more, 5 or more, or 7 or more. １～１０ The organic group may have 20 or less, 15 or less, 10 or less, 5 or less, or 3 or less carbon atoms, and preferably 5 or less.

[0021] OSiR ａ R ｂ R ｃ or NR ｄ R ｅ R in ａ～ｅ R is independently a hydrogen atom or an organic group in each occurrence. ｄ and R ｅ may be bonded to each other to form a ring.

[0022] R ａ～ｅ The organic group in A may be an aliphatic group or an aromatic group, and is preferably an aliphatic group (e.g., an aliphatic hydrocarbon group). １～１０ The organic group in R may be a heteroatom-containing group or a hydrocarbon group, and is preferably a hydrocarbon group (e.g., an aliphatic hydrocarbon group). ａ～ｅ The organic group of R may be linear, branched, or cyclic, and is preferably linear. ａ～ｅ The number of carbon atoms in the organic group may be 1 or more, 2 or more, 3 or more, 5 or more, or 7 or more. ａ～ｅ The organic group may have 20 or less, 15 or less, 10 or less, 5 or less, or 3 or less carbon atoms, and preferably 5 or less.

[0023] For example, A １～１０ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decanyl), an alkenyl group having 2 to 10 carbon atoms (e.g., vinyl or 2-propenyl), an alkynyl group having 2 to 10 carbon atoms (e.g., ethynyl or propynyl), a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl or cyclobutyl), an aryl group having 4 to 10 carbon atoms (e.g., cyclopentadienyl or phenyl), a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), or OSiR ａ R ｂ R ｃ Siloxy groups (e.g., trimethylsiloxy or dimethylsiloxy) represented by the formula: ｄ R ｅ A may be an amino group represented by the formula (e.g., methylamino, ethylamino, dimethylamino, diethylamino, propylamino, isopropylamino, dipropylamino, diisopropylamino, pyrrolidino, or piperidino), and is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (methyl, ethyl, propyl, or isopropyl). １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may be taken together as an oxygen atom to form a cyclic siloxane. １～１０ Each of the hydrocarbon groups in may independently be branched or straight chain, preferably straight chain.

[0024] In formula (1), p and q are each an integer selected from 1 to 5, for example, (p, q) = (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (1, 2), (4, 5).

[0025] The molecular weight of the sulfur-containing siloxane may be 200 or more, 250 or more, 300 or more, or 350 or more. The molecular weight of the sulfur-containing siloxane may be 1000 or less, 900 or less, 800 or less, or 700 or less, and is preferably 700 or less.

[0026] The number of carbon atoms in the sulfur-containing siloxane may be 0 or more, 1 or more, 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more. The number of carbon atoms in the sulfur-containing siloxane may be 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or 25 or less.

[0027] The presence of multiple Si-O structures in one molecule is preferable from the viewpoint of film properties when forming a silicon oxide film, since the constituent elements are similar to the film composition. Furthermore, although the detailed reason is unclear, the presence of Si-S structures is preferable from the viewpoint of film formation methods under high temperature conditions. Meanwhile, from the viewpoint of film formability and vapor pressure control, molecular size is also important. After extensive research, the present inventors have found that a sulfur-containing siloxane having an appropriate number of Si-O structures and an appropriate molecular weight, as specified above, can produce favorable effects.

[0028] [Cyclic Siloxane] The sulfur-containing siloxane in the present disclosure can be cyclic siloxane.For example, the sulfur-containing siloxane in the present disclosure can be bis(cyclotrisiloxanyl)sulfide compound, bis(cyclotetrasiloxanyl)sulfide compound, bis(cyclopentasiloxanyl)sulfide compound, bis(cyclohexasiloxanyl)sulfide compound, (cyclotrisiloxanyl)thiocyclotetrasiloxane compound, (cyclotrisiloxanyl)thiocyclopentasiloxane compound, (cyclotrisiloxanyl)thiocyclohexasiloxane compound, (cyclotetrasiloxanyl)thiocyclopentasiloxane compound, (cyclotetrasiloxanyl)thiocyclohexasiloxane compound or (cyclopentasiloxanyl)thiocyclohexasiloxane compound.

[0029] The sulfur-containing siloxane of the present disclosure is particularly a siloxane represented by the following formula (2): [In formula (2), R １～３are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; and n and m are each independently an integer of 1 to 4.

[0030] In formula (2), R １～３ R each independently in each occurrence is a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms (for example, an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decanyl), an alkenyl group having 2 to 10 carbon atoms (e.g., vinyl or 2-propenyl), or an alkynyl group having 2 to 10 carbon atoms (e.g., ethynyl or propynyl), preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (methyl, ethyl, propyl, or isopropyl)). １～３ The hydrocarbon group in each occurrence may independently be branched or straight-chain, preferably straight-chain.

[0031] In formula (2), all R １～３ The ratio of the number of groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups) among all R may be 0% or more, 10% or more, 30% or more, 50% or more, or 70% or more, for example, 50% or more, for example, 100%. １～３ The ratio of the number of groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups) among these may be 90% or less, 70% or less, 50% or less, 30% or less, or 0. Each —Si may have 0 or one or more (e.g., 1 or 2) groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups).

[0032] In formula (2), in the sulfur-containing siloxane, all R １ and R ２ At least one (e.g., one or more, two or more) of each —SiR １ R ２ R in O- １ and R ２ At least one (eg, one or both) of may be a hydrogen atom.

[0033] In formula (2), R １ and R ２ may be the same or different from each other, and R １～３ may be the same or different from each other.

[0034] In formula (2), n and m are integers selected from 1 to 4, for example, n=m=2. When p, q, n, and m are within the above ranges, excellent film-forming properties can be achieved. For example, the sulfur-containing siloxane is a compound in which n and m are 2 and the compound is represented by the following formula (3): [In formula (3), R １～３ and each occurrence independently represent a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0035] Examples of sulfur-containing siloxanes that are cyclic siloxanes include bis(cyclotrisiloxanyl) sulfide, bis(2,4,6-trimethylcyclotrisiloxanyl) sulfide, bis(2,4,6-triethylcyclotrisiloxanyl) sulfide, bis(2,4,4,6,6-pentamethylcyclotrisiloxanyl) sulfide, bis(2,4,4,6,6-pentaethylcyclotrisiloxanyl) sulfide, bis(2,4,4,6,6-pentaphenylcyclotrisiloxanyl) sulfide, bis(cyclotetrasiloxanyl) sulfide, bis(2 ,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide, bis(2,4,6,8-tetraethylcyclotetrasiloxanyl) sulfide, bis(2,4,4,6,6,8,8-heptamethylcyclotetrasiloxanyl) sulfide, bis(2,4,4,6,6,8,8-heptaethylcyclotetrasiloxanyl) sulfide, bis(2,4,4,6,6,8,8-heptaphenylcyclotetrasiloxanyl) sulfide, bis(cyclopentasiloxanyl) sulfide, bis(2,4,6,8,10-pentamethylcyclopentasiloxanyl) Sulfide, bis(2,4,6,8,10-pentaethylcyclopentasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10-nonamethylcyclopentasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10-nonaethylcyclopentasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10-nonaphenylcyclopentasiloxanyl) sulfide, bis(cyclohexasiloxanyl) sulfide, bis(2,4,6,8,10,12-hexamethylcyclohexasiloxanyl) sulfide , bis(2,4,6,8,10,12-hexaethylcyclohexasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10,12,12-undecamethylcyclohexasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10,12,12-undecaethylcyclohexasiloxanyl) sulfide, bis(2,4,4,6,6,8,8,10,10,12,12-undecaphenylcyclohexasiloxanyl) sulfide, 2-[(2',4',6'-trimethylcyclotrisiloxan-2'-yl)thio]-2,4,6,8-tetramethylcyclotetrasiloxane, 2-[(2',4',6'-trimethylcyclotrisiloxane-2'-yl)thio]-2,4,6,8,10-pentamethylcyclopentasiloxane, 2-[(2',4',6'-trimethylcyclotrisiloxane-2'-yl)thio]-2,4,6,8,10,12-hexamethylcyclohexasiloxane, 2-[(2',4',6',8'-tetramethylcyclotetrasiloxane-2'-yl)thio]-2,4,6,8,10-pentamethylcyclopentasiloxane, 2-[(2',4',6' ,8'-tetramethylcyclotetrasiloxane-2'-yl)thio]-2,4,6,8,10,12-hexamethylcyclohexasiloxane or 2-[(2',4',6',8',10'-pentamethylcyclopentasiloxane-2'-yl)thio]-2,4,6,8,10,12-hexamethylcyclohexasiloxane, etc.

[0036] The sulfur-containing siloxane in the present disclosure is represented by the following formula (4): The compound may be bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide represented by the formula:

[0037] [Acyclic siloxane] The sulfur-containing siloxane in the present disclosure may be an acyclic siloxane.For example, the sulfur-containing siloxane in the present disclosure may be a bis(disiloxanyl)sulfide compound, a bis(trisiloxanyl)sulfide compound, a bis(tetrasiloxanyl)sulfide compound, a bis(pentasiloxanyl)sulfide compound, a (disiloxanyl)thiotrisiloxane compound, a (disiloxanyl)thiotetrasiloxane compound, a (disiloxanyl)thiopentasiloxane compound, a (trisiloxanyl)thiotetrasiloxane compound, a (trisiloxanyl)thiopentasiloxane compound, or a (tetrasiloxanyl)thiopentasiloxane compound.

[0038] The sulfur-containing siloxane of the present disclosure is particularly a siloxane represented by the following formula (5): [In formula (5), R １～３are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; and p and q are each independently an integer of 1 to 5.

[0039] In formula (5), R １～３ R each independently in each occurrence is a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms (for example, an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decanyl), an alkenyl group having 2 to 10 carbon atoms (e.g., vinyl or 2-propenyl), or an alkynyl group having 2 to 10 carbon atoms (e.g., ethynyl or propynyl), preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (methyl, ethyl, propyl, or isopropyl)). １～３ The hydrocarbon group in each occurrence may independently be branched or straight-chain, preferably straight-chain.

[0040] In formula (5), all R １～３ The ratio of the number of groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups) among all R may be 0% or more, 10% or more, 30% or more, 50% or more, or 70% or more, for example, 50% or more, for example, 100%. １～３ The ratio of the number of groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups) among these may be 90% or less, 70% or less, 50% or less, 30% or less, or 0. Each —Si may have 0 or one or more (e.g., 1 or 2) groups other than hydrogen atoms (monovalent aliphatic hydrocarbon groups).

[0041] In formula (5), in the sulfur-containing siloxane, all R １ and R ２ At least one (e.g., one or more, two or more) of the -SiR groups may be a hydrogen atom, but it is preferable that the sulfur-containing siloxane has a plurality of monovalent aliphatic hydrocarbon groups. １ R ２ R in O- １ and R ２At least one (e.g., one or both) of R may be a monovalent aliphatic hydrocarbon group, １～３ may all be monovalent aliphatic hydrocarbon groups.

[0042] In formula (5), R １ and R ２ may be the same or different from each other, and R １～３ may be the same or different from each other.

[0043] In addition, p and q in formula (5) are each an integer selected from 1 to 5, for example, (p, q) = (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (1, 2), (4, 5). For example, the sulfur-containing siloxane has p and q of 1 and is represented by the following formula (6): [In formula (6), R １～１０ and each occurrence independently represent a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0044] Examples of sulfur-containing siloxanes that are acyclic siloxanes include bis(disiloxanyl) sulfide, bis(1,1,3,3-tetramethyldisiloxanyl) sulfide, bis(1,1,3,3-tetraethyldisiloxanyl) sulfide, bis(1,1,3,3-tetrapropyldisiloxanyl) sulfide, bis(1,1,3,3-tetraisopropyldisiloxanyl) sulfide, bis(1,1,1,3,3-pentamethyldisiloxanyl) sulfide, bis(1,1,1,3,3-pentaethyldisiloxanyl) sulfide, bis(1,1,1, bis(1,1,1,3,3-pentapropyldisiloxanyl) sulfide, bis(1,1,1,3,3-pentaisopropyldisiloxanyl) sulfide, bis(trisiloxanyl) sulfide, bis(1,1,3,3,5,5-hexamethyltrisiloxanyl) sulfide, bis(1,1,3,3,5,5-hexaethyltrisiloxanyl) sulfide, bis(1,1,3,3,5,5-hexapropyltrisiloxanyl) sulfide, bis(1,1,3,3,5,5-hexaisopropyltrisiloxanyl) sulfide, bis(1,1,1,3,3,5,5-hepta methyltrisiloxanyl) sulfide, bis(1,1,1,3,3,5,5-heptaethyltrisiloxanyl) sulfide, bis(1,1,1,3,3,5,5-heptapropyltrisiloxanyl) sulfide, bis(1,1,1,3,3,5,5-heptaisopropyltrisiloxanyl) sulfide, (disiloxanyl)thiotrisiloxane, (1,1,3,3-tetramethyldisiloxanyl)thiotrisiloxane, (1,1,3,3-tetraethyldisiloxanyl)thiotrisiloxane, (1,1,1,3,3-pentamethyldisiloxanyl)thio Otrisiloxane, (1,1,1,3,3-pentaethyldisiloxanyl)thiotrisiloxane, (1,1,3,3-tetramethyldisiloxanyl)thio-1,1,3,3,5,5,5-pentamethyltrisiloxane, (1,1,3,3-tetraethyldisiloxanyl)thio-1,1,3,3,5,5,5-pentamethyltrisiloxane, (1,1,1,3,3-pentamethyldisiloxanyl)thio-1,1,3,3,5,5,5-pentamethyltrisiloxane, (1,1,1,3,3-pentaethyldisiloxanyl)thio-1,1,3,3,5,5,5-pentamethyltrisiloxane, etc.

[0045] The sulfur-containing siloxane in the present disclosure is represented by the following formula (7): It may also be bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide represented by the formula:

[0046] <Method for Producing Sulfur-Containing Siloxane> The method for producing a sulfur-containing siloxane in the present disclosure may include a production method including: (a) a step of synthesizing a sulfur-containing siloxane from a raw material siloxane; and (b) a distillation step of isolating the sulfur-containing siloxane by distillation.

[0047] [Synthesis Step (a)] The synthesis step (a) may include a step of reacting a raw material siloxane with a sulfurizing agent.

[0048] The raw material siloxanes are represented by the following formulas (8-1) and (8-2): [In formula (8-1) and formula (8-2), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; p and q are each independently an integer of 1 to 5; and Z is a halogen or a hydrogen atom. １～１０ The aspects of p and q are as explained above.

[0049] The raw material siloxane has the following formula (8-3): [In formula (8-3), R １～３are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; Z is a halogen or a hydrogen atom; and n is an integer of 1 to 4. １ , R ２ , R ３ and n are as described above.

[0050] The raw material siloxane has the following formula (8-4): [In formula (8-4), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, Z is a halogen or a hydrogen atom, and p is an integer of 1 to 5. １～３ , p and q are as described above.

[0051] Examples of Z include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and a hydrogen atom.

[0052] The molecular weight of the starting siloxane may be 100 or more, 150 or more, 200 or more, or 250 or more. The molecular weight of the starting siloxane may be 750 or less, 600 or less, 500 or less, or 400 or less, and is preferably 500 or less.

[0053] The carbon number of the starting siloxane may be 0 or more, 1 or more, 3 or more, 5 or more, 7 or more, 10 or more, 12 or more, or 15 or more. The carbon number of the sulfur-containing siloxane may be 30 or less, 25 or less, 20 or less, 15 or less, or 10 or less.

[0054] The starting siloxane may be synthesized in advance before use. For example, a siloxane compound in which Z is a hydrogen atom may be used as is in the synthesis step (a), or Z may be substituted with a halogen using a halogenating agent before the synthesis step (a) is carried out. The halogenating agent may be a fluorinating agent, a chlorinating agent, a brominating agent, or an iodinating agent. Among these, chlorinating agents such as N-chlorosuccinimide and N-chlorophthalimide are preferably used.

[0055] The sulfurizing agent is a sulfur compound capable of substituting sulfur for Z in --SiZ, and sulfides such as lithium sulfide, sodium sulfide, and hydrogen sulfide can be used.

[0056] An example of the reaction between the raw material siloxanes (8-1) and (8-2) and the sulfurizing agent is shown below: Formula (9-1):

[0057] An example of the reaction between the raw material siloxane (8-3) and the sulfurizing agent is shown below: Formula (9-2):

[0058] An example of the reaction between the raw material siloxane (8-4) and the sulfurizing agent is shown below: Reaction Formula (9-3):

[0059] In step (a), either a method in which the starting siloxane is first dissolved in an organic solvent and then the sulfurizing agent is added thereto, or a method in which the sulfurizing agent is dissolved in an organic solvent and then the starting siloxane is added thereto, can be used in this reaction.

[0060] The amount of sulfurizing agent used is usually 0.2 to 3.0 moles, preferably 0.4 to 2.0 moles (for example, 0.5 to 1.0 mole) per 1.0 mole of the starting siloxane.

[0061] The reaction may be carried out at a temperature in the range of −20° C. to 100° C., preferably −10° C. to 60° C. The reaction time is usually in the range of 0.5 to 30 hours.

[0062] Examples of solvents that can be used in the present disclosure include hydrocarbons such as hexane, cyclohexane, heptane, nonane, and decane; halogenated hydrocarbons such as dichloroethane, dichloromethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, and trichlorobenzene; ethers such as diethyl ether, tetrahydrofuran (THF), and ethylene glycol dimethyl ether, and mixtures thereof. Among these, ethers such as diethyl ether and tetrahydrofuran (THF) are preferred, with tetrahydrofuran (THF) being particularly preferred. The amount of solvent used is typically 0.1 to 50 times the mass of the starting siloxane compound.

[0063] To avoid hydrolysis of siloxanes and sulfur-containing siloxanes, it is desirable to carry out the reaction under anhydrous conditions, with the moisture content of all raw materials used being in the range of 0 to 5000 ppm by mass, preferably 0 to 500 ppm by mass, based on the mass of all raw materials. It is also desirable to use a reaction apparatus that has been dried by heating, reducing the pressure, or replacing the atmosphere with an inert gas such as nitrogen or argon.

[0064] In step (a), if solids such as by-product salts are present in the reaction solution, filtration may be carried out after the reaction is completed, if necessary.When filtration is carried out, it is desirable to carry out the filtration under a dry inert gas, for example, nitrogen or argon, in order to suppress the decomposition of the sulfur-containing siloxane.The filtration temperature is not uniquely determined, but can be applied from 10°C to the boiling point of the solvent used.Preferably, it is desirable to carry out the filtration in the range of 20°C to 65°C.

[0065] [Distillation step (b)] In step (b), the sulfur-containing siloxane is isolated by distillation, for example, vacuum distillation. The sulfurizing agent and organic solvent can be easily removed, and the sulfur-containing siloxane can be purified to a sufficiently high purity.

[0066] <Method for Producing Silicon-Containing Film> The sulfur-containing siloxane according to the present disclosure can be used as an intermediate for forming a silicon-containing film on a substrate. The method for forming a silicon-containing film according to the present disclosure can be chemical vapor deposition, particularly atomic layer deposition. More specifically, the method for forming a silicon-containing film according to the present disclosure includes: (c) adding a compound represented by the following formula (1) to a substrate: [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; Rａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; p and q are each independently an integer of 1 to 5.] to adsorb the sulfur-containing siloxane composition onto a substrate; (d) a step of purging the unadsorbed sulfur-containing siloxane composition and by-products; (e) a step of injecting a reactive gas into the substrate to which the sulfur-containing siloxane composition has been adsorbed, thereby decomposing the sulfur-containing siloxane to form an atomic layer; and (f) a step of purging the unreacted reactive gas and by-products.

[0067] The substrate temperature may be 100 to 800°C, preferably 100 to 750°C. From the viewpoint of the film properties to be obtained, the substrate temperature may be 200°C or higher, 300°C or higher, 400°C or higher, 500°C or higher, 600°C or higher, or 700°C or higher, for example, 250°C or higher, preferably 300°C or higher, 400°C or higher, or 500°C or higher. The film formation temperature may be the temperature of at least one of steps (c) to (f), for example, the temperature of the substrate when it is brought into contact with the sulfur-containing siloxane composition in step (c). Silicon-containing films obtained from the sulfur-containing siloxane of the present disclosure are stable even at high temperatures, and the sulfur-containing siloxane of the present disclosure can be suitably used in silicon-containing film production methods that employ high substrate temperatures.

[0068] The pressure during gas injection in steps (c) and (e) is 0.05 to 100 Torr, preferably 0.05 to 50 Torr.

[0069] In the step (e), when a silicon oxide film having Si—O bonds is formed, one or more gases selected from oxygen, ozone, and nitrogen monoxide can be used as the reactive gas, and when a silicon nitride film having Si—N bonds is formed, one or more gases selected from nitrogen, ammonia, nitrous oxide, nitric oxide, and nitrogen dioxide can be used.

[0070] The formation of the silicon-containing film is preferably carried out after replacing the atmosphere with an inert gas such as nitrogen or argon, i.e., after replacing the atmosphere inside the reaction system with an inert gas, the above step (c) is preferably carried out.

[0071] The sulfur-containing siloxanes of the present disclosure are suitable for use in producing silicon-containing films (silicon oxide films, silicon nitride films, etc.) by the ALD method. In the method for producing a silicon-containing film of the present disclosure, the lower limit of the ALD window may be 300°C, preferably 350°C. Furthermore, in the method for producing a silicon-containing film of the present disclosure, the upper limit of the ALD window may be 800°C, preferably 750°C. Here, the ALD window generally refers to the temperature range between the vaporization temperature and the thermal decomposition temperature of a silicon-containing film precursor compound. In this specification, the ALD window can be defined as the temperature range from the point at which the deposition rate becomes maximum to the point at which the deposition rate becomes minimum, with the film formation temperature on the horizontal axis and the deposition rate on the vertical axis.

[0072] The present disclosure will be described in detail below with reference to examples.

[0073] Example 1: Synthesis of bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide After purging with nitrogen, 7.7 g (0.17 mol) of lithium sulfide and 82.1 g of tetrahydrofuran were added to a 500 mL flask equipped with a thermometer, a condenser, and a motor stirrer. While stirring at room temperature, 145.9 g of a solution containing 72.6 g (0.26 mol) of 2-chloro-2,4,6,8-tetramethylcyclotetrasiloxane was slowly added dropwise over 30 minutes. After the dropwise addition, the mixture was stirred for 23 hours while maintaining the temperature at 26 to 33°C. Subsequently, solids produced as a by-product, primarily lithium chloride, were removed by vacuum filtration in a nitrogen-purged glove box, yielding a tetrahydrofuran solution containing bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide. This tetrahydrofuran solution was distilled under reduced pressure at an internal temperature of 60 to 80°C to remove tetrahydrofuran, and further distilled under reduced pressure at an internal temperature of 145°C and 0.6 Torr using a distillation column to obtain bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide in high purity.

[0074] GC analysis after distillation confirmed that 19.0 g (yield 28.1%) of bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide was obtained with a purity of 96.2 area %. 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.

[0075] １ H-NMR (400MHz, CDCl3): δ0.21-0.28(m, 18H, [CH ３ -SiH-]), δ0.48-0.51,6H,[CH ３ -SiS]), δ 4.71-4.79 (m, 6H, [Si-H]) １ The results of H-NMR and GC-MS showed that the obtained sulfur-containing siloxane had the following formula: The compound was identified as bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide, represented by the formula:

[0076] Example 2: Formation of a Silicon-Containing Film Using Bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) Sulfide A silicon substrate was placed in a vacuum chamber and heated to a predetermined temperature of 100 to 750°C. A siloxane composition containing bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide and a carrier gas obtained in Example 1 was injected at a pressure of 0.05 to 100 Torr and adsorbed onto the heated silicon substrate. Argon gas was then introduced into the chamber to purge any unadsorbed sulfur-containing siloxane composition and by-products. Ozone was then injected as a reactive gas at a pressure of 0.05 to 100 Torr, forming an atomic layer of silicon oxide derived from bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide deposited on the substrate. Argon gas was then introduced to purge any unreacted ozone and by-products. The above cycle was repeated to obtain a silicon oxide film.

[0077] Example 3: Synthesis of bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide After nitrogen purge, 274 g (1.85 mol) of pentamethyldisiloxane and 1,700 g of tetrahydrofuran were added to a 3 L flask equipped with a thermometer, a condenser, and a motor stirrer. 244 g (1.83 mol) of N-chlorosuccinimide was added while stirring at room temperature. After the addition, the mixture was stirred for 5 hours while maintaining the temperature at 56 to 59°C. The tetrahydrofuran was then removed by vacuum distillation at an internal temperature of 60 to 80°C. The by-product solid was removed by vacuum filtration in a nitrogen-purged glove box, yielding a tetrahydrofuran solution containing chloropentamethyldisiloxane. This tetrahydrofuran solution was further distilled under reduced pressure at an internal temperature of 100°C and 175 Torr using a distillation column to yield a tetrahydrofuran solution containing high-purity chloropentamethyldisiloxane. Subsequently, after purging with nitrogen, 8.7 g (0.19 mol) of lithium sulfide and 96 g of tetrahydrofuran were added to a 300 mL flask equipped with a thermometer, a condenser, and a motor stirrer. 68 g of the tetrahydrofuran solution containing 56 g (0.31 mol) of chloropentamethyldisiloxane obtained earlier was slowly added dropwise over 40 minutes while stirring at room temperature. After the dropwise addition, the mixture was stirred for 4 hours while maintaining the temperature at 26 to 33°C. Subsequently, the solid by-product, primarily lithium chloride, was removed by vacuum filtration in a nitrogen-purged glove box, yielding a tetrahydrofuran solution containing bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide. This tetrahydrofuran solution was subjected to vacuum distillation at an internal temperature of 60 to 80°C to remove the tetrahydrofuran, and further vacuum distillation was performed using a distillation column at an internal temperature of 84°C and 2.2 Torr to obtain bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide in high purity.

[0078] GC analysis after distillation confirmed that 27 g (18% yield) of bis(1,1,1,3,3-pentamethyldisiloxan-3-yl) sulfide had been obtained with a purity of 98.0 area %. The resulting bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide was identified by 1H-NMR and GC-MS. The 1H-NMR assignments are as follows. The 1H-NMR chart is shown in Figure 3.

[0079] 1H-NMR (400MHz, CDCl ３ ):δ0.12(s,18H,[CH ３ -Si]), δ0.40(s,12H,[CH ３ From the results of the 1H-NMR and GC-MS, it was found that the obtained sulfur-containing siloxane had the following formula: The compound was identified as bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide, represented by the formula:

[0080] Example 4: Formation of a silicon-containing film using bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide A silicon substrate was placed in a vacuum chamber and heated to a predetermined temperature of 100 to 750°C. A siloxane composition containing bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide obtained in Example 3 and a carrier gas was injected at a pressure of 0.05 to 100 Torr and adsorbed onto the heated silicon substrate. Argon gas was then introduced into the chamber to purge any unadsorbed sulfur-containing siloxane composition and by-products. Ozone was then injected as a reactive gas at a pressure of 0.05 to 100 Torr, forming an atomic layer of silicon oxide derived from bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide deposited on the substrate. Argon gas was then introduced to purge any unreacted ozone and by-products. The above cycle was repeated to obtain a silicon oxide film.

[0081] Comparative Example 1: Formation of a silicon-containing film using bis(diethylaminosilane) A silicon substrate was placed in a vacuum chamber and heated to a predetermined temperature of 100 to 750°C. An aminosilane composition containing bis(diethylaminosilane) and a carrier gas was injected at a pressure of 0.05 to 100 Torr and adsorbed onto the heated silicon substrate. Argon gas was then introduced to purge the chamber of any unadsorbed aminosilane composition and by-products. Ozone was then injected as a reactive gas at a pressure of 0.05 to 100 Torr, forming an atomic layer of silicon oxide derived from bis(diethylaminosilane) deposited on the substrate. Argon gas was then introduced to purge any unreacted ozone gas and by-products. The above cycle was repeated to obtain a silicon oxide film.

[0082] Comparative Example 2: Formation of a Silicon-Containing Film Using 2-Dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane A silicon substrate was placed in a vacuum chamber and heated to a predetermined temperature of 100 to 750°C. A siloxane composition containing 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane and a carrier gas was injected at a pressure of 0.05 to 100 Torr and adsorbed onto the heated silicon substrate. Argon gas was then introduced into the chamber to purge any unadsorbed aminosiloxane composition and by-products. Ozone was then injected as a reactive gas at a pressure of 0.05 to 100 Torr, forming an atomic layer of silicon oxide derived from 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane deposited on the substrate. Argon gas was then introduced to purge any unreacted ozone gas and by-products. The above cycle was repeated to obtain a silicon oxide film.

[0083] Comparative Example 3: Formation of a Silicon-Containing Film Using Triethoxy-[3-(trimethoxysilyl)propylthio]silane A silicon substrate was placed in a vacuum chamber and heated to a predetermined temperature of 100 to 750°C. A siloxane composition containing triethoxy-[3-(trimethoxysilyl)propylthio]silane and a carrier gas was injected at a pressure of 0.05 to 100 Torr and adsorbed onto the heated silicon substrate. Argon gas was then introduced into the chamber to purge any unadsorbed aminosiloxane composition and by-products. Ozone was then injected as a reactive gas at a pressure of 0.05 to 100 Torr, forming an atomic layer of silicon oxide derived from triethoxy-[3-(trimethoxysilyl)propylthio]silane deposited on the substrate. Argon gas was then introduced to purge any unreacted ozone gas and by-products. The above cycle was repeated to obtain a silicon oxide film.

[0084] Table 1 below shows a specific deposition method. Figure 2 shows the relationship between substrate temperature and deposition rate. The siloxane supply time that maximized the deposition rate was selected for each plot in Figure 2. Table 2 shows the deposition rates in Example 2 when 50 cycles were repeated at substrate temperatures of 400°C and 725°C, which are the minimum and maximum temperatures in the ALD window. Table 3 shows the deposition rates in Example 4 when 50 cycles were repeated at substrate temperatures of 500°C and 750°C, which are the minimum and maximum temperatures in the ALD window. The ALD window here refers to the temperature range from the point where the deposition rate reaches its maximum to its minimum in Figure 2. Table 4 also summarizes the temperature ranges of the ALD window for Examples 2 and 4, and Comparative Examples 1, 2, and 3. The layer thicknesses were measured using an ellipsometer.

[0085]

[0086] As shown in Table 2, the supply time of the bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide composition was investigated in Example 2 to form an atomic layer of silicon oxide derived from the bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide compound. At a substrate temperature of 400°C, the deposition rate reached its maximum at 15 seconds or more, and at a substrate temperature of 725°C, the deposition rate reached its maximum at 6 seconds or more, confirming that ALD film formation was possible at both temperatures.

[0087] As shown in Table 3, the supply time of the bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide composition was investigated in Example 4 to form an atomic layer of silicon oxide derived from the bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide compound. At a substrate temperature of 500°C, the deposition rate reached its maximum at 6 seconds or more, and at a substrate temperature of 750°C, the deposition rate reached its maximum at 6 seconds or more, confirming that ALD film formation was possible at both temperatures.

[0088] As shown in Table 4 and FIG. 2, it was confirmed that the temperature region (ALD window) in which ALD film formation is possible for bis(2,4,6,8-tetramethylcyclotetrasiloxanyl)sulfide and bis(1,1,1,3,3-pentamethyldisiloxane-3-yl)sulfide is located on the higher side than those for bisdiethylaminosilane, 2-dimethylamino-2,4,6,8-tetramethylcyclotetrasiloxane, and triethoxy-[3-(trimethoxysilyl)propylthio]silane.

[0089] By using atomic deposition, it is possible to form an ultrathin silicon oxide film that is free of atomic defects even on semiconductor substrates or nanowires that have high aspect ratios. The sulfur-containing siloxanes according to the present disclosure are useful for atomic deposition, which involves film formation at high temperatures.

Claims

1. Below formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a siloxane ring, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; p and q each independently represent an integer of 1 to 5. Sulfur-containing siloxanes represented by the formula:

2. A １ and A ３ are taken together as oxygen atoms to form a cyclic siloxane, and A ４ and A ６ The sulfur-containing siloxane of claim 1 , wherein together with an oxygen atom, form a cyclic siloxane.

3. Below formula (2) [In formula (2), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; n and m each independently represent an integer of 1 to 4. The sulfur-containing siloxane according to claim 1 or 2, wherein

4. 3. The sulfur-containing siloxane according to claim 1, having a molecular weight of 1,000 or less.

5. 3. The sulfur-containing siloxane according to claim 1, wherein the number of carbon atoms in the sulfur-containing siloxane is 50 or less.

6. Below formula (3): [In formula (3), R １～３ In each occurrence, each independently represents a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms. The sulfur-containing siloxane according to claim 1 or 2, wherein

7. Below formula (4): The sulfur-containing siloxane according to claim 1 or 2, which is bis(2,4,6,8-tetramethylcyclotetrasiloxanyl) sulfide represented by the formula:

8. Below formula (5): [In formula (5), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; p and q each independently represent an integer of 1 to 5. The sulfur-containing siloxane according to claim 1 or 2, wherein

9. Below formula (6): [In formula (6), R １～３ In each occurrence, each independently represents a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms. The sulfur-containing siloxane according to claim 1 or 2, wherein

10. Below formula (7): The sulfur-containing siloxane according to claim 1 or 2, which is bis(1,1,1,3,3-pentamethyldisiloxane-3-yl) sulfide represented by the formula:

11. A precursor of a silicon-containing film comprising the sulfur-containing siloxane of claim 1 or 2.

12. The precursor of claim 11 , wherein the silicon-containing film is formed by chemical vapor deposition.

13. 12. The precursor of claim 11, wherein the silicon-containing film is formed by atomic layer deposition.

14. A composition for forming a silicon-containing film, comprising the sulfur-containing siloxane according to claim 2.

15. The composition of claim 14 , wherein the silicon-containing film is formed by chemical vapor deposition.

16. The composition of claim 14 , wherein the silicon-containing film is formed by atomic layer deposition.

17. Below formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; p and q each independently represent an integer of 1 to 5. A method for producing a sulfur-containing siloxane represented by the formula: (a) synthesizing the sulfur-containing siloxane from a raw material siloxane; and (b) isolating the sulfur-containing siloxane by distillation. A method for producing a sulfur-containing siloxane, comprising:

18. 18. The method for producing a sulfur-containing siloxane according to claim 17, wherein in step (a), the raw material siloxane is reacted with a sulfurizing agent to synthesize the sulfur-containing siloxane.

19. The raw material siloxane is represented by the following formula (8-3): [In formula (8-3), R １～３ are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; Z is a halogen or hydrogen atom; n is an integer from 1 to 4. or a compound represented by Below formula (8-4): [In formula (8-4), R １～３ each occurrence independently represents a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; Z is a halogen or hydrogen atom; and p is an integer from 1 to 5. A compound represented by 19. The method for producing a sulfur-containing siloxane according to claim 17 or 18,

20. Below formula (1): [In formula (1), A １～１０ each occurrence independently represents a hydrogen atom, an organic group, a halogen, or OSiR ａ R ｂ R ｃ or a siloxy group represented by NR ｄ R ｅ where A is an amino group represented by １ and A ３ may be taken together with an oxygen atom to form a cyclic siloxane, A ４ and A ６ may together be an oxygen atom to form a cyclic siloxane; R ａ～ｅ is independently in each occurrence a hydrogen atom or an organic group; R ｄ and R ｅ may be bonded to each other to form a ring; p and q each independently represent an integer of 1 to 5. A method for producing a silicon-containing film using a sulfur-containing siloxane represented by the formula:

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