JP2017160115A - Cyclic silane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cyclic silane composition which has excellent long-term storage stability and can be suitably used for e.g. the production of semiconductors.SOLUTION: A cyclic silane composition comprises cyclohexasilane. The content of a silane compound represented by the following structural formula (1) is 1% or less based on cyclohexasilane.SELECTED DRAWING: None

Description

The present invention relates to a cyclic silane composition. More specifically, the present invention relates to a cyclic silane composition containing cyclohexasilane.

Hydrogenated silane compounds are used in the field of semiconductor manufacturing. In recent years, it has been proposed to use a cyclic silane compound such as cyclohexasilane as a raw material for producing semiconductors in place of the conventional monosilane compound (Patent Document 1). A method for producing an epitaxial Si-containing thin film by vapor deposition has been proposed. In addition, a method of forming a polysilane by photopolymerization by forming a solution layer having cyclopentasilane or cyclohexasilane as a solute on a substrate has been reported (Patent Document 3).

JP 60-26664 A Special table 2013-537705 gazette JP 2013-187261 A

As described above, cyclohexasilane is promising as a next-generation semiconductor raw material because it can produce high-performance Si-containing thin films. However, it is difficult to say that it has good stability because it reacts with a very small amount of oxygen and easily forms an oxide. For this reason, problems such as the generation of impurities may occur when cyclohexasilane is stored.
Therefore, an object of the present invention is to provide a cyclic silane composition which has good storage stability and can be preferably used, for example, for semiconductor manufacturing applications.

The present inventor has made various studies in order to achieve the above object, and arrived at the present invention.
That is, the cyclic silane composition contains cyclohexasilane, and the content of the silane compound (silyl-cyclohexasilane) represented by the following structural formula (1) is 1% or less with respect to cyclohexasilane. It is a silane composition.

  Another cyclic silane composition of the present invention contains cyclohexasilane, the content of the silane compound represented by the structural formula (1) is 1% or less with respect to cyclohexasilane, and the following structural formula (2- The total content of the compound represented by 1) (hydroxycyclohexasilane) and the compound represented by the following structural formula (2-2) (one oxide of cyclohexasilane) is 1 with respect to cyclohexasilane. % Is a cyclic silane composition.

The cyclic silane compound of the present invention has good long-term storage stability. Therefore, since it is difficult to generate impurities, it is possible to suppress variations in products.

Hereinafter, the present invention will be described in detail.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[Cyclic silane composition of the present invention]
<Cyclic silane composition of the present invention>
The cyclic silane composition of the present invention contains cyclohexasilane as an essential component. The cyclic silane composition of the present invention contains, for example, 60 mass% or more and 99.9999 mass% or less of cyclohexasilane. The cyclic silane composition of the present invention more preferably contains 80% by mass or more of cyclohexasilane, and more preferably 90% by mass or more of cyclohexasilane. In the cyclic silane composition of the present invention, the cyclohexasilane content is more preferably 99.999% by mass or less, and further preferably the cyclohexasilane content is 99.99% by mass or less.

The cyclic silane composition of the present invention is characterized in that the content of the silane compound represented by the structural formula (1) is 1% or less with respect to cyclohexasilane. Preferably it is 0.5% or less, More preferably, it is 0.1% or less. Further, the content of the silane compound represented by the structural formula (1) is preferably 0.0001% or more, more preferably 0.001% or more with respect to cyclohexasilane. More preferably, it is 01% or more.
If it is the said range, it exists in the tendency for the long-term storage stability of a cyclic silane composition to improve.

  In addition, about content of the silane compound represented by the said Structural formula (1),% with respect to cyclohexasilane is the peak intensity of the silane compound represented by the said Structural formula (1) and cyclohexasilane in a gas chromatography. It can be calculated from (area). That is, the above% can also be expressed as area%. The measurement conditions for gas chromatography are as described later.

The cyclic silane composition of the present invention comprises a compound represented by the following structural formula (2-1) (hydroxycyclohexasilane) and a compound represented by the following structural formula (2-2) (one oxide of cyclohexasilane). ) Is preferably 1% or less with respect to cyclohexasilane. More preferably, it is 0.5% or less, More preferably, it is 0.1% or less. The total content of the compound represented by the following structural formula (2-1) and the compound represented by the following structural formula (2-2) is 0.0001% or more with respect to cyclohexasilane. Is more preferably 0.001% or more, still more preferably 0.01% or more.
If it is the said range, it exists in the tendency for the long-term storage stability of a cyclic silane composition to improve.
In addition, regarding the total content of the compound represented by the following structural formula (2-1) and the compound represented by the following structural formula (2-2),% relative to cyclohexasilane is the above structural formula (1). It can be calculated from the peak intensity (area) of gas chromatography in the same manner as the% in the content of the silane compound represented.

  In the cyclic silane composition of the present invention, the content of the silane compound represented by the following structural formula (3) is preferably 2% or less with respect to cyclohexasilane. More preferably, it is 1% or less, More preferably, it is 0.5% or less. In addition, the content of the silane compound represented by the structural formula (3) is more preferably 0.0001% or more, further preferably 0.001% or more with respect to cyclohexasilane, More preferably, the content is 0.01% or more.

If it is the said range, it exists in the tendency for the storage stability of a cyclic silane composition to improve.
In addition, about content of the silane compound represented by the said Structural formula (3),% with respect to cyclohexasilane of gas chromatography is the same as% in content of the silane compound represented by the said Structural formula (1). It can be calculated from the peak intensity (area).

  In the cyclic silane composition of the present invention, the content of a silane compound (silyl-cyclopentasilane) represented by the following structural formula (7) is preferably 1% or less with respect to cyclohexasilane. More preferably, it is 0.5% or less, More preferably, it is 0.1% or less. In addition, the content of the silane compound represented by the structural formula (7) is more preferably 0.0001% or more, further preferably 0.001% or more, based on cyclohexasilane. More preferably, the content is 0.01% or more.

If it is the said range, it exists in the tendency for the storage stability of a cyclic silane composition to improve.
In addition, about content of the silane compound represented by the said Structural formula (7),% with respect to cyclohexasilane of gas chromatography is the same as% in content of the silane compound represented by the said Structural formula (1). It can be calculated from the peak intensity (area).

  The cyclic silane composition of the present invention can contain a silane compound other than the compounds represented by the structural formulas (1) to (3) and (7) as desired. The content of the silane compound other than the compounds represented by the structural formulas (1) to (3) and (7) in the cyclic silane composition of the present invention is 0% by mass or more and 2% or less with respect to cyclohexasilane. It is preferably 0% by mass or more and 1% or less, and more preferably 0% by mass or more and 0.5% or less.

  The cyclic silane composition of the present invention may contain an organic solvent or the like as desired. Examples of the organic solvent include ether solvents such as diethyl ether, tetrahydrofuran, and cyclopentyl methyl ether; aprotic polar solvents such as acetonitrile; hydrocarbon solvents such as hexane and toluene; The content of the organic solvent in the cyclic silane composition of the present invention is not limited as long as the content of cyclohexane is in the above range.

  Since the cyclic silane composition of the present invention is usually stored under an inert atmosphere such as nitrogen, helium, or argon, these gases may be dissolved. For example, it is preferably 0.0001 ml or more, more preferably 0.001 ml or more, with respect to 1 ml of the cyclic silane composition of the present invention (the upper limit of the dissolution amount is the saturation amount). If it is the said range, it exists in the tendency for the storage stability of a cyclic silane composition to improve (especially it exists in the tendency for generation | occurrence | production of cloudiness (insoluble matter) to be suppressed).

  The cyclic silane composition of the present invention preferably has a metal component content as low as possible. For example, each metal is preferably 1 ppm or less, more preferably 100 ppb or less, and even more preferably 10 ppb or less.

The cyclic silane composition of the present invention preferably has as few turbid components (insoluble matter) as possible. Specifically, it is preferable that the cyclic silane composition of the present invention is not visually turbid.
The cyclic silane composition of the present invention is slightly turbid even when diluted with a poor solvent, but preferably has high transparency, and more preferably no turbidity is observed even when diluted with a poor solvent.
In addition, the cyclic silane composition of the present invention is also one of preferred embodiments in which the insoluble content when dissolved in hexane at a concentration of 2 mass% is 0.1 mass% or less. More preferably, it is 0.01 mass% or less, More preferably, it is 0.001 mass% or less. It is particularly preferable that turbidity cannot be confirmed visually.

<Method for Producing Cyclic Silane Composition of the Present Invention>
Although the cyclic silane of the present invention is not particularly limited, (I) a step of cyclizing the halosilane compound to produce a cyclic halosilane compound (cyclization step), and (II) a step of reducing the cyclic halosilane compound (reduction step); It is preferable to produce as essential. Moreover, it is more preferable to include the process (purification process) (III) which refine | purifies a cyclic silane compound.

  Examples of the halosilane compound in the cyclization step include trihalogenated silanes such as trichlorosilane, tribromosilane, triiodosilane, and trifluorosilane; dihalogenated silanes such as dichlorosilane, dibromosilane, diiodosilane, and difluorosilane; tetra Tetrahalogenated silanes such as chlorosilane, tetrabromosilane, tetraiodosilane, and tetrafluorosilane can be used. Among these, trihalogenated silane is preferable, and trichlorosilane is particularly preferable.

In the cyclization step, the reaction is preferably performed in the presence of the following coordination compounds (i) to (iv). (Ii) a tertiary polyamine; (ii) a quaternary phosphonium salt or a quaternary ammonium salt; (iii) a compound represented by XR _n (when X is P or P = O, n = 3; R represents the same or different substituted or unsubstituted alkyl group or aryl group, and when X is S, S═O or O, n = 2, and R is the same or different substituted or unsubstituted alkyl group. or an aryl group, X is when the CN is n = 1, R represents a substituted or unsubstituted alkyl group or an aryl group. However, the number of amino groups in the XR _n is 0 or 1. (Iv) at least one heterocyclic compound selected from the group consisting of substituted or unsubstituted heterocyclic compounds containing N, O, S or P having an unshared electron pair in the ring, provided that the heterocyclic ring As a substituent of the compound The number of grade amino group is 0 or 1.). As the coordination compounds (i) to (iv), one or more selected from the coordination compounds (i) to (iv) may be used, or two or more may be used.

The tertiary polyamine of the above (i) is a compound containing two or more tertiary amino groups in one molecule, and N, N, N ′, N ″, N ″ -pentaethyldiethylenetriamine (Pedeta), Examples thereof include N, N, N, N ′, N′-tetraethylethylenediamine (Teeda) and the like. When the halosilane compound is cyclized in the presence of the tertiary polyamine (i) above, a dianion complex is formed. For example, when trichlorosilane is cyclized in the presence of Pedeta, [Pedeta.SiH ₂ Cl ⁺ ] ₂ [Si ₆ Cl ₁₄ ⁻² ], which is a tetradecalolocyclohexasilane dianion complex, is produced.

The quaternary phosphonium salts of the above (ii), but are not limited _{to, R 1 R 2 R 3 R} 4 P + · X - called (general formula _(4), R 1 to R ₄ are each independently , A hydrogen atom, an alkyl group, and an aryl group, and X ⁻ represents a monovalent anion).

The quaternary ammonium salt of the above (ii), but are not limited _{to, R 5 R 6 R 7 R} 8 N + · Y - called (general formula _(5), R 5 ~R ₈ are each independently , A hydrogen atom, an alkyl group, and an aryl group, and Y ⁻ represents a monovalent anion).

When the halosilane compound is cyclized in the presence of the coordination compound (ii) above, a dianion complex is formed. For example, when trichlorosilane is cyclized in the presence of a quaternary phosphonium salt, [R ₁ R ₂ R ₃ R ₄ P ⁺ ] ₂ [Si ₆ Cl ₁₄ ⁻² ] which is a tetradecalolocyclohexasilane dianion complex When trichlorosilane is cyclized in the presence of a quaternary ammonium salt, [R ₅ R ₆ R ₇ R ₈ N ⁺ ] ₂ [Si ₆ Cl ₁₄ ⁻² ] is generated.

Examples of the alkyl group which is an example of R _{1 to} R ₄ in the general formula (4) and R _{5 to} R ₈ in the general formula (5) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, hexyl group, heptyl group, octyl group, an alkyl group having 1 to 16 carbon atoms such as cyclohexyl group are preferably mentioned, _R 1 to R ₄ in the general formula (4), _{R 5} in the general formula (5) As the aryl group as an example of ˜R ₈ , an aryl group having about 6 to 18 carbon atoms such as a phenyl group and a naphthyl group is preferably exemplified. Among these, as R1 to R8, a butyl group and a phenyl group are particularly preferable. R _{1 to} R ₄ and R _{5 to} R ₈ may be different from each other, but are preferably all the same group.

Examples of the monovalent anion represented by X ⁻ in the general formula (4) and Y ⁻ in the general formula (5) include halide ions (Cl ⁻ , Br ⁻ , I ⁻ etc.), borate ions (BF ₄ ⁻ Etc.), phosphorus anions (PF ^6- etc.) And the like. Among these, from the viewpoint of easy availability, Cl ⁻ , Br ⁻ and I ⁻ are preferable, and Cl ⁻ and Br ⁻ are particularly preferable. In addition, ammonium salt and quaternary phosphonium salt may each use only 1 type, and may use 2 or more types together.

In XR _n of the (iii), X forms a neutral complex coordinated with cyclic silane. When X is P or P = O, X is trivalent and n indicating the number of R is 3. R is the same or different and represents a substituted or unsubstituted alkyl group or aryl group. R is more preferably a substituted or unsubstituted aryl group. When R is an alkyl group, examples thereof include a linear, branched or cyclic alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a cyclohexyl group. A C1-C16 alkyl group, such as group, is mentioned preferably. In addition, when R is an aryl group, an aryl group having about 6 to 18 carbon atoms such as a phenyl group and a naphthyl group is preferable.

In XR _n of the (iii), when X is N (provided that the number of amino groups in the XR _n is 1.) Also, X may form a neutral complex coordinated with cyclic silane. When X is N, X is trivalent and n indicating the number of R is 3. R is the same or different and represents a substituted or unsubstituted alkyl group or aryl group. R is more preferably a substituted or unsubstituted alkyl group. When R is an alkyl group, examples thereof include a linear, branched, or cyclic alkyl group, preferably an alkyl group having 1 to 16 carbon atoms, and having 1 to 1 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group. 4 alkyl groups are more preferable, and alkyl groups having 1 to 3 carbon atoms are more preferable. In addition, when R is an aryl group, an aryl group having about 6 to 18 carbon atoms such as a phenyl group and a naphthyl group is preferable.

In XR _n when X is P and P = O or when X is N, the alkyl group may have an alkoxy group, amino group, cyano group, carbonyl group, sulfonyl group. Examples of the substituent that the aryl group may have include an alkoxy group, an amino group, a cyano group, a carbonyl group, and a sulfonyl group. The amino group is dimethylamino group and a diethylamino group, the number of amino groups in XR _3, is 1 or less. The intent is to exclude tertiary polyamines. The three Rs may be the same or different.

  When X is S, S = O, O, X is divalent and n indicating the number of R is 2. R has the same meaning as R in the case where X is P and P = O, and is a substituted or unsubstituted alkyl group or aryl group. R is more preferably a substituted or unsubstituted aryl group. When X is CN, X is monovalent and n indicating the number of R is 1. Also in this case, R has the same meaning as R in the case where X is P and P = O, and is a substituted or unsubstituted alkyl group or aryl group. R is more preferably a substituted or unsubstituted aryl group.

Specific examples of the compound (iii) include X such as triphenylphosphine (PPh ₃ ), triphenylphosphine oxide (Ph ₃ P═O), and tris (4-methoxyphenyl) phosphine (P (MeOPh) ₃ ). Are compounds in which X is S = O such as dimethyl sulfoxide; compounds in which X is CN such as p-tolunitrile (also referred to as p-methylbenzonitrile).

  In the heterocyclic compound of (iv) above, it is necessary to have an unshared electron pair in the ring, and this unshared electron pair coordinates to the cyclic halosilane to form a cyclic halosilane neutral complex. . Examples of such a heterocyclic compound include one or more substituted or unsubstituted heterocyclic compounds containing N, O, S, or P having a loan pair in the ring. The substituent that the heterocyclic compound may have is the same as the substituent that R may have when it is an aryl group. Examples of the heterocyclic compound include pyridines, imidazoles, pyrazoles, oxazoles, thiazoles, imidazolines, pyrazines, thiophenes, and furans. Specific examples include N, N-dimethyl-4-aminopyridine, tetrahydrothiophene, tetrahydrofuran and the like.

  In the cyclization step, in the case of the coordination compound (i) or (ii), the coordination compound is used in an amount of 0.01 mol or more and 0.5 mol or less with respect to 1 mol of Si atom contained in the halosilane compound. It is preferably 0.05 mol or more and 0.4 mol or less, more preferably 0.08 mol or more and 0.3 mol or less; more preferably (iii) or (iv) coordination In the case of a compound, it is preferably used in an amount of 0.1 mol or more and 8 mol or less, more preferably 0.1 mol or more and 4 mol or less, and more preferably 0.1 mol per 1 mol of Si atoms contained in the halosilane compound. More preferably, 1 mol or less is used.

  The cyclization step is preferably performed in the presence of a tertiary amine (excluding tertiary polyamine). This is because the generated hydrogen halide can be neutralized. Examples of the tertiary amine used in the cyclization step include triethylamine, tripropylamine, tributylamine, trioctylamine, triisobutylamine, triisopentylamine, diethylmethylamine, diisopropylethylamine (DIPEA), dimethylbutylamine. , Dimethyl-2-ethylhexylamine, diisopropyl-2-ethylhexylamine, methyl dioctylamine and the like are preferable. Two or more tertiary amines may be used in combination. In the cyclization step, the tertiary amine is preferably used in an amount of 0.5 to 4 mol with respect to 1 mol of the halosilane compound. More preferably, it is 0.8-1.5 mol.

  The cyclization step (especially when (i) and / or (ii) is used as a coordination compound, it may be carried out in the presence of a compound represented by the following general formula (6). The following structural formula (6) It is presumed that it contributes to the cyclization coupling reaction of a halosilane compound as a compound chelate type ligand represented by the formula (1).

In the general formula (6), Z ¹ represents N, O, P or S, Z ² represents O, P or S, and R and R ″ each independently has 1 to 20 carbon atoms. Represents an organic group which may contain O, P, S or a halogen atom and may have a linear structure, a branched structure, an alicyclic structure or an aromatic ring structure, and R ′ represents a hydrogen atom or a carbon linear structure having 1 to 6, have a branched structure or a ring structure represents an organic group, Z1 is when l = 2, Z ¹ when the N or P is O or S be l = 1 M = 2 when Z ² is P, m = 1 when Z ² is O or S, n is an integer of 1 to 5, and when there are a plurality of R, R ′ or R ″, May be the same or different. In the general formula (6), Z ¹ is N, O, P or S, Z ² is O, P or S, but Z ¹ is preferably O or P, and Z ² is O or P P is preferred. More preferably, Z ¹ and Z ² are the same element.

  In the said General formula (6), n should just be an integer of 1-5, However, 4 or less are preferable, More preferably, it is 3 or less, More preferably, it is 2 or less.

  In the general formula (6), R ′ is a hydrogen atom or an organic group having 1 to 6 carbon atoms (such as a hydrocarbon group), and particularly preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Is preferably a hydrogen atom. In particular, among a plurality (2n) of R ′, the number of hydrogen atoms is preferably 0.5n or more, more preferably n or more, and even more preferably 1.5n or more is a hydrogen atom. Good. When R ′ is an organic group, the carbon number is preferably 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably 1 to 3 carbon atoms. In addition, each R ′ or two R ′ bonded to the same carbon atom may be the same or different, but may be bonded to a plurality of R ′, particularly the same carbon atom. The two R ′ are desirably the same. The organic group represented by R ′ in the general formula (6) may have a linear structure, a branched structure, or a ring structure, and two R ′s out of 2n R ′ are directly They may be bonded to form a ring (examples where two R's are directly bonded to form a ring include dialkoxycyclohexanes such as 1,1-dimethoxycyclohexane). In the general formula (6), specific examples of the organic group represented by R ′ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n— Examples thereof include alkyl groups such as a butyl group, a s-butyl group, a t-butyl group, a pentyl group, and a hexyl group. Examples of those having a ring structure include a cyclohexyl group. In the general formula (6), R and R ″ are each independently O, P, S or halogen having 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms). It is an organic group which may contain atoms (preferably Cl, Br, I, etc.), and R and R ″ may be different but are preferably the same. Further, when there are a plurality of R or R ″, it is desirable that they are the same.

  The organic group represented by R or R ″ in the general formula (6) may have a linear structure, a branched structure, an alicyclic structure, or an aromatic ring structure. One R ″ may be directly bonded to form a ring (an example in which one R and one R ″ are directly bonded to form a ring includes dioxane, 4-methyl-1 Substituent dioxane such as 1,3-dioxane, dioxolane and the like are applicable.) In the general formula (6), specific examples of the organic group represented by R and R ″ include a linear structure or a branched structure, Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group Alkyl groups such as As having a cyclohexyl group, adamantyl group and the like, as having an aromatic ring structure, phenyl, benzyl, 1-naphthyl and an aryl group of 2-naphthyl and the like.

  As the compound (chelate type ligand) represented by the general formula (6), a compound containing two or more O or P is particularly preferable in order to develop a good chelating ability. Specific examples of preferred chelate ligands include, for example, 1,1-dimethoxyethane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dipropoxy as compounds containing two O atoms. Ethane, 1,2-diisopropoxyethane, 1,2-dibutoxyethane, 1,2-diphenoxyethane, 1,3-dimethoxypropane, 1,3-diethoxypropane, 1,3-dipropoxypropane, 1,3-diisopropoxypropane, 1,3-dibutoxypropane, 1,3-diphenoxypropane, 1,4-dimethoxybutane, 1,4-diethoxybutane, 1,4-dipropoxybutane, 1, Examples include dialkoxyalkanes such as 4-diisopropoxybutane, 1,4-dibutoxybutane, 1,4-diphenoxybutane, and particularly preferably 1, - dimethoxyethane. Specific examples of preferred chelate-type ligands include, for example, 1,2-bis (dimethylphosphino) ethane, 1,2-bis (diethylphosphino) ethane, -Bis (dipropylphosphino) ethane, 1,2-bis (dibutylphosphino) ethane, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (dimethylphosphino) propane, 1,3- Bis (diethylphosphino) propane, 1,3-bis (dipropylphosphino) propane, 1,3-bis (dibutylphosphino) propane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (Dimethylphosphino) butane, 1,4-bis (diethylphosphino) butane, 1,4-bis (dipropylphosphino) butane, 1,4-bis (dibuty) Bis (dialkylphosphino) alkanes and bis (diarylphosphino) alkanes such as phosphino) butane and 1,4-bis (diphenylphosphino) butane are mentioned, and 1,2-bis (diphenylphosphino) is particularly preferred. ) Ethane. In addition, the compound (chelate type ligand) shown by general formula (i) may use only 1 type, and may use 2 or more types together.

  The use amount (total use amount) of the compound (chelate type ligand) represented by the general formula (6) is preferably 0.01 mol or more and 50 mol or less, more preferably 0 with respect to 1 mol of the halosilane compound. .05 mol or more and 40 mol or less, more preferably 0.1 mol or more and 30 mol or less.

  The said cyclization process can be implemented in an organic solvent as needed. Examples of the organic solvent include halogenated hydrocarbon solvents (eg, chloroform, dichloromethane, 1,2-dichloroethane), ether solvents (eg, diethyl ether, tetrahydrofuran, cyclopentyl methyl ether, diisopropyl ether, methyl tertiary butyl ether, etc.). ), Hydrocarbon solvents (for example, hexane, heptane, benzene, toluene, etc.), and aprotic polar solvents such as acetonitrile are preferred. Among these, chlorinated hydrocarbon solvents such as chloroform, dichloromethane and 1,2-dichloroethane are preferable, and 1,2-dichloroethane is particularly preferable. In addition, these organic solvents may use only 1 type and may use 2 or more types together. In the cyclization step, the amount of the organic solvent used is not particularly limited, but it is usually preferable to adjust the concentration of the halosilane compound to be 0.5 to 10 mol / L, and a more preferable concentration is 0.8 to 8 mol / L, more preferably 1 to 5 mol / L.

  In the cyclization step, the reaction temperature can be appropriately set according to the reactivity, and is, for example, about 0 to 120 ° C, preferably about 15 to 70 ° C. The cyclization reaction is preferably performed in an inert gas atmosphere such as nitrogen.

  When performing the said cyclization process by batch reaction, it is preferable to use the capacity | capacitance of the reaction kettle of 20L or more. When the reaction kettle within the above range is used, the content of the compounds represented by the structural formulas (1) to (3) and (7) in the cyclic silane composition tends to be in an appropriate range, and the cyclic silane composition There is a tendency for the storage stability of to improve. The upper limit is, for example, 20,000 L or less.

When the cyclic halosilane compound obtained in the cyclization step is a dianion complex, for example, J. Org. Tillmann et al. “Lewis acidity of Si ₆ Cl ₁₂ and its roles As Convenient SiCl ₂ source”, Inorganic Chemistry, vol. 54, p. 9611 (2015) and the like, by contacting the cyclic halosilane dianion complex with a Lewis acid, a deligandation reaction is performed, and Si ₆ X ₁₂ (X is F, Cl, Br, I), etc. May be generated (deliganding step).

  Although the kind of Lewis acid used at the said deliganding process is not specifically limited, It is preferable to use a metal halide. Examples of the metal halide include metal chloride, metal bromide, metal iodide, and the like. From the viewpoint of reactivity and ease of control of reaction, metal chloride is preferably used. The metal elements constituting the metal halide include group 13 elements such as boron, aluminum, gallium, indium and thallium, group 11 elements such as copper, silver and gold, group 4 elements such as titanium and zirconium, iron, zinc, Examples include calcium. Specific examples of the Lewis acid used in the deligandation step include boron halides such as boron trifluoride, boron trichloride, and boron tribromide; aluminum halides such as aluminum chloride and aluminum bromide; Gallium halides such as gallium and gallium bromide; Indium halides such as indium chloride and indium bromide; Thallium halides such as thallium chloride and thallium bromide; Copper halides such as copper chloride and copper bromide; Silver chloride; Silver halides such as silver bromide; Gold halides such as gold chloride and gold bromide; Titanium halides such as titanium chloride and titanium bromide; Zirconium halides such as zirconium chloride and zirconium bromide; Iron chloride and bromide Iron halides such as iron; zinc halides such as zinc chloride and zinc bromide; calcium halides such as calcium chloride and calcium bromide Etc. The.

  The amount of Lewis acid used in the deliganding step may be adjusted as appropriate according to the reactivity between the cyclic halosilane dianion complex and the Lewis acid. It is preferably 0.5 mol or more, more preferably 1.5 mol or more, more preferably 20 mol or less, and even more preferably 10 mol or less.

  The reaction between the cyclic halosilane dianion complex and the Lewis acid is preferably carried out in a solvent or dispersion medium (these are simply referred to as a solvent). Examples of the solvent (reaction solvent) used in the reaction include hydrocarbon solvents such as hexane and toluene; ether solvents such as diethyl ether, tetrahydrofuran, cyclopentyl methyl ether, diisopropyl ether, and methyl tertiary butyl ether. These organic solvents may use only 1 type and may use 2 or more types together. The reaction solvent is preferably subjected to purification such as distillation or dehydration before the reaction in order to remove water and dissolved oxygen contained therein.

  The reaction temperature for the reaction between the cyclic halosilane dianion complex and the Lewis acid may be appropriately adjusted according to the reactivity. For example, it is preferably −80 ° C. or higher, more preferably −50 ° C. or higher, and −30. More preferably, it is preferably 200 ° C. or lower, more preferably 150 ° C. or lower, and further preferably 100 ° C. or lower.

  Cyclic halosilane compounds (cyclic halosilane anion complex and cyclic halosilane neutral complex obtained in the cyclization step, cyclic halosilane obtained through the deligandation step after the cyclization step) are, for example, chloroform, dichloromethane, It may be washed with 2-dichloroethane or acetonitrile (washing step). When the cyclization reaction or the like is performed using a solvent, the reaction solution may be concentrated and then washed.

In the reduction step, the cyclic halosilane compound is reduced to produce a cyclic silane compound. Although it does not restrict | limit especially as a reducing agent which can be used in the said reduction | restoration process, It is preferable to use 1 or more types chosen from the group which consists of an aluminum-type reducing agent and a boron-type reducing agent. Examples of the aluminum reducing agent include lithium aluminum hydride (LiAlH ₄ ; LAH), diisobutylaluminum hydride (DIBAL), sodium bis (2-methoxyethoxy) aluminum hydride (“Red-Al” (registered trademark of Sigma-Aldrich). And metal hydrides and the like. Examples of the boron-based reducing agent include metal hydrides such as sodium borohydride and lithium triethylborohydride, and diborane. In addition, only 1 type may be used for a reducing agent and it may use 2 or more types together.

  What is necessary is just to set the usage-amount of the reducing agent in a reduction process suitably, for example, it is preferable that the equivalent of the hydride in a reducing agent with respect to one silicon-halogen bond of a cyclic halosilane compound shall be at least 0.9 equivalent or more. More preferably, it is 0.9-50 equivalent, More preferably, it is 0.9-30 equivalent, Most preferably, it is 0.9-15 equivalent, Most preferably, it is 0.9-2 equivalent. If the amount of the reducing agent used is too large, the post-treatment takes time and the productivity tends to decrease. On the other hand, if it is too small, the yield tends to decrease.

  In the reduction step, a Lewis acid catalyst may be used in combination with the reducing agent as a reduction aid. Lewis acid catalysts include chlorides such as aluminum chloride, titanium chloride, zinc chloride, tin chloride and iron chloride; bromides such as aluminum bromide, titanium bromide, zinc bromide, tin bromide and iron bromide; Iodides such as aluminum, titanium iodide, zinc iodide, tin iodide and iron iodide; fluorides such as aluminum fluoride, titanium fluoride, zinc fluoride, tin fluoride and iron fluoride; A metal compound is mentioned. These may use only 1 type and may use 2 or more types together.

  The reaction in the reduction step can be performed in the presence of an organic solvent, if necessary. Examples of the organic solvent that can be used here include hydrocarbon solvents such as hexane and toluene; ether solvents such as diethyl ether, tetrahydrofuran, cyclopentyl methyl ether, diisopropyl ether, and methyl tertiary butyl ether; These organic solvents may use only 1 type and may use 2 or more types together. Moreover, the organic solvent solution obtained when producing the cyclic halosilane compound may be used as it is as the organic solvent solution in the reduction step, or the organic solvent is distilled off from the organic solvent solution containing the cyclic halosilane compound, A new organic solvent may be added to carry out the reduction step. The organic solvent used for the reaction in the reduction step is preferably purified by distillation or dehydration before the reaction in order to remove water and dissolved oxygen contained therein.

  The amount of the organic solvent used for the reduction reaction is preferably adjusted so that the concentration of the cyclic halosilane compound is 0.01 to 1 mol / L, more preferably 0.02 to 0.7 mol / L, still more preferably. Is 0.03-0.5 mol / L. If the amount of the organic solvent used is too small, the heat generated by the reduction reaction may not be sufficiently removed, and problems such as a decrease in the reaction rate due to the difficulty of dissolving the reactants may occur. On the other hand, when the amount of the organic solvent used is too large, the amount of the solvent to be distilled off when the organic solvent and the target product are separated after the reduction reaction increases, so that the productivity tends to decrease.

  The reduction reaction in the reduction step can be performed by bringing a cyclic halosilane compound and a reducing agent into contact with each other. The contact between the cyclic halosilane compound and the reducing agent is preferably performed in the presence of an organic solvent. In order to bring the cyclic halosilane compound and the reducing agent into contact with each other in the presence of an organic solvent, for example, (1) the reducing agent is directly added to the solution or dispersion of the cyclic halosilane compound, and (2) the solution or dispersion of the cyclic halosilane compound. A mixing procedure such as adding a solution or dispersion in which a reducing agent is dissolved or dispersed in a solvent to the solution, or (3) adding a cyclic halosilane compound and a reducing agent simultaneously or sequentially in the solvent may be employed. Among these, the embodiment (2) is particularly preferable.

  When one or both of the cyclic halosilane compound and the reducing agent are added dropwise in the above-described embodiments A) to C), the concentration of the cyclic halosilane compound solution or dispersion is preferably 0.01 mol / L or more, more preferably 0.8. 02 mol / L or more, more preferably 0.04 mol / L or more, particularly preferably 0.05 mol / L or more. If the concentration of the cyclic halosilane compound is too low, the amount of solvent that must be distilled off when isolating the target product increases, so that productivity tends to decrease. On the other hand, the upper limit of the concentration of the cyclic halosilane compound solution or dispersion is preferably 1 mol / L or less, more preferably 0.8 mol / L or less, and still more preferably 0.5 mol / L or less.

  In the reduction step, the temperature at the time of dropping (specifically, the temperature of the dropping solution or dispersion) may be appropriately set according to the kind of the cyclic halosilane compound and the reducing agent, and the lower limit is usually preferably -198. ° C or higher, more preferably -160 ° C or higher, still more preferably -100 ° C or higher. Moreover, the upper limit of the temperature at the time of dripping becomes like this. Preferably it is +150 degrees C or less, More preferably, it is +100 degrees C or less, More preferably, it is +80 degrees C or less, Most preferably, it is +40 degrees C or less. The reduction reaction temperature (temperature of the reaction solution) may be appropriately set according to the kind of the cyclic halosilane compound and the reducing agent, and is usually preferably −198 ° C. or higher, more preferably −160 ° C. or higher, and −100 More preferably, it is not lower than ° C. The reduction reaction temperature is preferably + 150 ° C. or less, more preferably + 100 ° C. or less, more preferably + 80 ° C. or less, still more preferably + 40 ° C. or less, particularly preferably −10 ° C. or less, and most preferably −60 ° C. It is as follows. When the reduction reaction temperature is low, decomposition and polymerization of the intermediate product and the target product can be suppressed, so that the yield is improved. The reaction time may be appropriately determined according to the progress of the reaction, but is usually 10 minutes or longer and 72 hours or shorter, preferably 1 hour or longer and 48 hours or shorter, more preferably 2 hours or longer and 24 hours or shorter. .

  The reduction reaction is usually preferably performed in an atmosphere of an inert gas such as nitrogen gas or argon gas.

The production method of the present invention preferably includes a step of purifying a reaction solution containing cyclohexasilane (for example, the reaction solution obtained in the reduction step) (purification step).
The reaction solution containing cyclohexasilane may separate solids (impurities such as by-produced salts) and the like, for example, by solid-liquid separation. The solid-liquid separation method is preferably employed in terms of simple filtration, but is not limited thereto, and for example, a known solid-liquid separation method such as centrifugation or decantation may be appropriately employed. it can. In addition, it is preferable to perform said solid-liquid separation operation in inert gas atmosphere, such as nitrogen gas.

  After the reduction reaction, the reaction solution is heated to 5 ° C. or higher, more preferably 10 ° C. or higher, more preferably 15 ° C. or higher, and then cooled again to 0 ° C. or lower, more preferably −5 ° C. or lower. It is preferable to perform solid-liquid separation such as filtration. By performing the above steps, the content of the compounds represented by the structural formulas (1) to (3) and (7) in the cyclic silane composition tends to be in an appropriate range, and the cyclic silane composition is stored. It tends to improve stability.

  The reaction solution containing cyclohexasilane may be separated from impurities by washing with a solvent that is not compatible with the reaction solution, or by extracting cyclohexasilane with a solvent that is not compatible with the reaction solution. You may do it. In the above case, the reaction solution and a solvent that is incompatible with the reaction solution may be stirred and mixed, or mixed by circulation. In the latter case, a line mixer such as a static mixer may be included in the path.

  The reaction liquid containing cyclohexasilane may remove impurities with an adsorbent. Examples of the adsorbent include molecular sieves 4A and 5A.

  The reaction liquid containing cyclohexasilane may be separated by distilling off the solvent. The solvent is preferably distilled off under reduced pressure. The heating time may be set to a short time by using a thin film evaporator or the like.

  The reaction solution containing cyclohexasilane is preferably purified by distillation. Distillation is preferably performed under reduced pressure, for example, 3 kPa or less, preferably 2 kPa or less, more preferably 1 kPa or less, further preferably 500 Pa or less, and even more preferably 300 Pa or less. preferable. The lower limit of the degree of vacuum is, for example, 1 Pa or more, and more preferably 10 Pa or more.

  The distillation is preferably performed under heating conditions, for example, 25 ° C or higher, preferably 30 ° C or higher, more preferably 35 ° C or higher, still more preferably 40 ° C or higher, for example, 100 ° C or lower, more preferably 90 ° C. or lower, more preferably 85 ° C. or lower.

  When the distillation step is performed, it is preferable to use a distillation pot having a capacity of 100 mL or more. When a distillation kettle in the above range is used, refluxing is likely to occur. Therefore, the content of the compounds represented by the structural formulas (1) to (3) and (7) in the cyclic silane composition tends to be in an appropriate range. Therefore, the storage stability of the cyclic silane composition tends to be improved.

  The bottom residue after distillation may be washed with a poor solvent such as pentane, hexane, heptane, octane, cyclohexane, cyclohexene, toluene, xylene and other hydrocarbon solvents; and the extracted components may be recycled to the distillation process. . By performing the above steps, it is possible to efficiently produce a cyclohexasilane composition, and the inclusion of the compounds represented by the structural formulas (1) to (3) and (7) in the cyclic silane composition The amount tends to be in an appropriate range, and the storage stability of the cyclic silane composition tends to be improved.

  Distillation may be performed only once or two or more times. When performing twice or more, you may change distillation conditions and distillation equipment, respectively, and may make it the same. For example, some or all of the distillation conditions described in JP2014-141398A and JP2015-71530A may be applied to the above method.

[Cyclic silane composition of the present invention]
You may use the cyclic silane composition of this invention as a semiconductor manufacturing raw material as it is. The cyclic silane composition of the present invention is further purified before use to reduce impurities (for example, compounds of the above structural formulas (1) to (3) and (7)) (for example, each less than 1 ppb) May be used.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Purity of cyclohexasilane, evaluation of content of compounds represented by structural formulas (1) to (3) and (7)>
In a gas chromatograph apparatus (“GC2014” manufactured by Shimadzu Corporation) equipped with a capillary column (“DB-1MS” manufactured by J & W SCIENTIFIC; 0.25 mm × 50 m), N ₂ is used as a carrier gas, the sample injection amount is 1 μL, and the sample injection temperature. 300 ° C., column temperature 50 ° C. (holding 5 minutes) to 20 ° C./minute (heating 10 minutes) to 10 ° C./minute (heating 5 minutes) to 300 ° C. (holding 10 minutes), detector FID (300 ° C.) The content of the compounds represented by the structural formulas (1) to (3) and (7) is determined by the gas chromatographic peak area of cyclohexasilane. It was calculated by comparing with the area of the peak.

<Evaluation of cyclic hexasilane composition>
Evaluation (I):
The cyclic silane composition is stored at 20 ° C. under a nitrogen atmosphere for 3 weeks, and the cyclic silane composition after storage is analyzed by ²⁹ Si-NMR (400 MHz: C ₆ D ₆ ). Those having a peak derived from the polymer were judged as having no stability.
Evaluation (II):
The cyclic silane composition was stored at 20 ° C. under a nitrogen atmosphere for 3 weeks, and the cyclohexasilane after storage was dissolved in dehydrated hexane so as to be 2% by mass, visually observed, and evaluated as follows. It was judged that the one with white turbidity was inferior in stability because it was considered that some impurities were generated.
◎ ⇒ No turbidity observed ⇒ Slightly turbid, but highly transparent × ⇒ Faintly cloudy.

<Example 1>
(Example 1-1)
After replacing the inside of a 20 L four-necked flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer with nitrogen gas, 1248 g (4.76 mol) of triphenylphosphine as a phosphine and 3672 g (28 of diisopropylethylamine as a basic compound) .41 mol) and 14.3 kg of 1,2-dichloroethane as a solvent. Subsequently, while stirring the solution in the flask, 3864 g (28.53 mol) of trichlorosilane was slowly added dropwise as a halosilane compound from a dropping funnel at 25 ° C. After completion of dropping, the mixture was stirred as it was for 2 hours, and then reacted by heating and stirring at 60 ° C. for 8 hours. The obtained reaction solution was concentrated and washed to obtain 1440 g of a nonionic dodecachlorocyclohexasilane-containing compound ([Ph ₃ P] ₂ [Si ₆ Cl ₁₂ ]) as a white solid.

(Example 1-2)
Into a 20 L four-necked flask equipped with a dropping funnel and a stirrer, 1337 g of the white solid obtained in Example 1-1 (1.2 mol of dodecachlorocyclohexasilane-containing compound) was added and dried under reduced pressure. Next, after the inside of the flask was replaced with argon gas, 7755 g of cyclopentyl methyl ether was added as a solvent. Subsequently, while stirring the suspension in the flask, 3400 mL of a lithium ether hydride solution (concentration: about 1.0 mol / L) as a reducing agent was gradually added dropwise from a dropping funnel at -70 ° C. Then, the reaction was carried out by stirring at −70 ° C. for 5 hours. After the reaction, the temperature was raised to 15 ° C. and then cooled again to −10 ° C., and the reaction solution was filtered under a nitrogen gas atmosphere to remove the generated salt. The solvent was distilled off under reduced pressure from the obtained filtrate to obtain a slurry containing crude cyclohexasilane. The obtained slurry was filtered, and the solvent was further distilled off under reduced pressure to obtain 115 g of a colorless and transparent liquid crude cyclohexasilane.

(Example 1-3)
115 g of the slurry containing the crude cyclohexasilane obtained in Example 1-2 was absolutely obtained using a general glass vacuum distillation apparatus (bottle, fractionation pipe, condenser, receiver) having a bottom size of 200 ml. Distilling at a pressure of 300 Pa, evaporating surface temperature (crude cyclohexasilane temperature in the kettle) of 75 ° C., condensing surface temperature (condenser set temperature) of 10 ° C., purified cyclohexasilane (cyclic silane composition of the present invention) Product).

When the obtained purified cyclohexasilane was analyzed by gas chromatography, it was found that cyclohexasilane was 98.7 area%, hexasilane was 0.4 area%, silylcyclopentasilane was 0.02 area%, silylcyclohexasilane. Was 0.8 area%, and a total of 0.001 area% of compounds in which cyclohexanesilane was oxidized was detected.
The obtained purified cyclohexanesilane was stored at 20 ° C. for 3 weeks in a nitrogen atmosphere. As a result of analyzing cyclohexasilane after storage by ²⁹ Si-NMR (400 MHz: C ₆ D ₆ ), no polymer component was observed. Moreover, as a result of performing said evaluation (II), turbidity was not observed.

<Comparative Example 1>
(Comparative Example 1-1)
After replacing the inside of a 500 mL four-necked flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer with nitrogen gas, 11.62 g (0.044 mol) of triphenylphosphine as phosphine, and diisopropylethylamine 34. as a basic compound. 4 g (0.266 mol) and 200 mL of 1,2-dichloroethane were added as a solvent. Subsequently, while stirring the solution in the flask, 36.0 g (0.266 mol) of trichlorosilane was slowly added dropwise as a halosilane compound from a dropping funnel at 25 ° C. After completion of dropping, the mixture was stirred as it was for 2 hours, and then reacted by heating and stirring at 60 ° C. for 8 hours. The obtained reaction liquid was concentrated and washed to obtain 12.5 g of a nonionic dodecachlorocyclohexasilane-containing compound ([Ph ₃ P] ₂ [Si ₆ Cl ₁₂ ]) as a white solid.

(Comparative Example 1-2)
In a 100 mL two-necked flask equipped with a dropping funnel and a stirrer, 2.44 g of the white solid obtained in Comparative Example 1-1 (2.18 mmol of dodecachlorocyclohexasilane-containing compound) was added and dried under reduced pressure. Next, after the inside of the flask was replaced with argon gas, 30 mL of diethyl ether was added as a solvent. Subsequently, while stirring the suspension in the flask, 10 mL of a lithium aluminum hydride diethyl ether solution (concentration: about 1.0 mol / L) was gradually added dropwise from a dropping funnel under a -70 ° C condition. Then, the reaction was carried out by stirring at −70 ° C. for 5 hours. After the reaction, the reaction solution was filtered under a nitrogen gas atmosphere to remove the generated salt. As a result of distilling off the solvent from the obtained filtrate under reduced pressure, although some solids were precipitated, crude cyclohexasilane was obtained as a colorless transparent liquid.

(Comparative Example 1-3)
Using 1.0 g crude cyclohexasilane obtained by repeatedly synthesizing Comparative 1-2 several times, using a small vacuum distillation apparatus (bottom, condenser, receiver) having a bottom size of 5 ml, an absolute pressure of 300 Pa and an external temperature of 75. Distillation was performed at 0 ° C. (the temperature of the bottom crude cyclohexasilane was equivalent to 75 ° C.) to obtain purified cyclohexasilane.

When the obtained purified cyclohexasilane was analyzed by gas chromatography, it was found that cyclohexasilane was 97.5 area%, hexasilane was 0.2 area%, silylcyclopentasilane was 0.06 area%, silylcyclohexasilane. Was detected at a ratio of 2.1 area%, and a compound in which cyclohexanesilane was oxidized was not detected.
The obtained purified cyclohexanesilane was stored at 20 ° C. for 3 weeks in a nitrogen atmosphere. As a result of analyzing the cyclohexasilane after storage by ²⁹ Si-NMR (400 MHz: C ₆ D ₆ ), a polymer component was confirmed. Note that cyclohexasilane immediately after purification was also analyzed by ²⁹ Si-NMR (400 MHz: C ₆ D ₆ ), but no polymer component could be confirmed.

  From the above results, it was revealed that the cyclic hexasilane composition of the present invention has good storage stability.

Claims (4)

A cyclic silane composition containing cyclohexasilane, wherein the content of a silane compound represented by the following structural formula (1) is 1% or less with respect to cyclohexasilane.

The total content of the compound represented by the following structural formula (2-1) and the compound represented by the following structural formula (2-2) including cyclohexasilane is 1% or less with respect to cyclohexasilane. The cyclic silane composition according to claim 1, wherein

The cyclic silane composition according to claim 1 or 2, wherein the content of a silane compound containing cyclohexasilane and represented by the following structural formula (3) is 2% by mass or less based on cyclohexasilane.

The cyclic silane composition according to any one of claims 1 to 3, wherein the content of a silane compound containing cyclohexasilane and represented by the following structural formula (7) is 1% by mass or less with respect to cyclohexasilane. object.