Method for purifying chlorosilanes

A purification method and technology of chlorosilanes, which are applied in the direction of halosilanes, chemical instruments and methods, silicon compounds, etc., can solve the problems of impracticality, reduced concentration rate, and increased discarding volume, etc.

CN102471076AInactive Publication Date: 2012-05-23SHIN ETSU CHEM CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2012-05-23
Estimated Expiration
Not applicable · inactive patent

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Abstract

Provided is a method for obtaining high-purity chlorosilanes from chlorosilanes that contain boron impurities or phosphorus impurities. On the basis of the finding that generation of solid byproducts when purifying chlorosilanes by adding aromatic aldehyde results from a reaction catalyzed by iron ions or rust-like iron, the disclosed method adds to the chlorosilanes a Lewis base that has a masking effect. Examples given for the Lewis base include divalent sulfur-containing compounds and alkoxysilanes. In the case of the former, R-S-R' is preferable (R representing a hydrocarbon group containing a C1-20 aliphatic or aromatic backbone; R' representing either a hydrocarbon group containing a C1-20 aliphatic or aromatic backbone, or a carbonyl group substituted with a hydrocarbon group containing a C1-20 aliphatic or aromatic backbone; and the total carbon number of R and R' being at least 7), and in the case of the latter, RxSi(OR')4-x is preferable (R and R' representing C1-20 alkyl groups and x being 0, 1, 2, or 3).
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Description

technical field

[0001] The present invention relates to a method for purifying chlorosilanes, and more particularly, to a method for obtaining high-purity chlorosilanes by removing impurities from chlorosilanes containing boron impurities and phosphorus impurities. Background technique

[0002] In general, polysilicon used as a raw material for manufacturing semiconductors and the like requires high purity. Therefore, it is required that chlorosilanes used as raw materials for producing polysilicon should have very high purity. For example, when boron and phosphorus are contained as impurities in chlorosilanes, even very small amounts of these impurities significantly affect the electrical properties (resistivity) of polysilicon. Therefore, it is practical to provide a technique for effectively removing boron impurities and phosphorus impurities contained in chlorosilanes.

[0003] Generally, crude chlorosilanes are obtained by a known method from metallurgical-grade silic...

Examples

Embodiment 1

[0088] In order to mask the iron involved in the reaction to form by-product solids, sulfur-containing compounds were added to confirm the effect as an inhibitor of solid by-product formation.

[0089] Specifically, 1 g of PhCHO, PhCH 2 Cl or PhCHCl 2 and 2g of SPh 2 、CH 3 SPh or CH 3 COSPh added to HSiCl 3 (20g), and further add 0.01g of FeCl to it 3 as a catalyst substance. These samples were placed in airtight containers and left to stand at normal temperature for a week to examine the state of solid by-product formation. The results are shown in Table 1.

[0090] Table 1

[0091]

[0092] ○: added ×: not added

[0093] According to the results shown in Table 1, in the above nine samples, after adding PhCHO and SPh 2 The formation of solid by-products was not observed in samples other than . These results show that using sulfur-containing compounds such as CH 3 SPh and SPh 2 effectively inhibits the PhCH 2 Cl and PhCHCl 2 Friedel-Crafts polymerization, whi...

Embodiment 2

[0101] In order to suppress the reaction of forming a by-product solid by polymerization of siloxane, an alkoxysilane was added to confirm the effect as a solid by-product formation inhibitor.

[0102] Specifically, 1 g of PhCHO, PhCH 2 Cl or PhCHCl 2 and 2 g of CH 3 Si(OCH 3 ) 3 or (CH 3 ) 2 Si(OCH 3 ) 2 Add to HSiCl 3 (20g), and further add 0.01g of FeCl to it 3 as a catalyst substance. These samples were placed in airtight containers and left to stand at normal temperature for a week to examine the state of solid by-product formation. The results are shown in Table 3.

[0103] table 3

[0104]

[0105] ○: added ×: not added

[0106] From this experiment, it was found that alkoxysilanes have an effect of inhibiting the polymerization of siloxane, and that alkoxysilanes have no effect of preventing by-product formation of benzylidene polymers, whereas sulfur-containing compounds have this effect.

Embodiment 3

[0114] An experiment for confirming the effect of using a sulfur compound and an alkoxysilane in combination was conducted.

[0115] Specifically, 1 g of PhCHO, PhCH 2 Cl or PhCHCl 2 and 2 g of CH as a sulfur compound 3 SPh and 2 g of CH as an alkoxysilane 3 Si(OCH 3 ) 3 Add to HSiCl 3 (20g), and further add 0.01g of FeCl to it 3 as a catalyst substance. These samples were placed in airtight containers and left to stand at normal temperature for a week to examine the state of solid by-product formation. The results are shown in Table 5.

[0116] table 5

[0117]

[0118] ○: added ×: not added

[0119] Solid by-product formation was not observed in any of the samples, and it was confirmed that the reaction to form a by-product solid could be suppressed by the synergistic effect of each inhibitory effect.