METHOD FOR PRODUCING TRICHLOROSILANE AND METHOD FOR PRODUCING POLYCRYSTALLINE SILICON

• US 20090060820A1
• Filed: 09/03/2008
• Published: 03/05/2009
• Est. Priority Date: 09/05/2007
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Oguro, Kyoji, Shimizu, Takaaki
• Granted Patent: US 7,790,132 B2
• Time in Patent Office: Days
• US Class Current: 423/342
• CPC Class Codes: C01B 33/03 by decomposition of silicon halides or halosilanes or reduction thereof with hydrogen as the only reducing agent
• CPC Class Codes: C01B 33/035 by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process
• CPC Class Codes: C01B 33/1071 Tetrachloride, trichlorosilane or silicochloroform, dichlorosilane, monochlorosilane or mixtures thereof

Abstract

The present invention includes a step of separating an effluent produced in a hydrogenation step of making tetrachlorosilane (STC) react with hydrogen into trichlorosilane (TCS), into a chlorosilane fraction containing a hydrocarbon and a TCS fraction, and a chlorination step of making the chlorosilane fraction containing the hydrocarbon react with chlorine to form STC and a substance containing a chlorinated hydrocarbon, wherein the effluent containing STC produced in the chlorination step is circulated to the hydrogenation step. In the chlorination step, the chlorosilane fraction containing a hydrocarbon (capable of containing hyper-hydrogenated chlorosilanes) having a boiling point close to TCS is hyper-chlorinated to be converted and acquire a higher boiling point, which facilitates the hyper-chlorinated chlorosilanes and the hyper-chlorinated hydrocarbons to be separated into high concentration, and increases the purity of TCS to be finally obtained.

Claims

1. A method for producing trichlorosilane comprising a hydrogenation step of making tetrachlorosilane (STC) react with hydrogen into trichlorosilane (TCS), a step of separating an effluent produced in the hydrogenation step into a chlorosilane fraction containing a hydrocarbon and a TCS fraction, and a chlorination step of making the chlorosilane fraction containing the hydrocarbon produced in the separation step react with chlorine to form STC and a substance containing a chlorinated hydrocarbon, wherein the effluent containing STC produced in the chlorination step is circulated to the hydrogenation step.

2. The method for producing the trichlorosilane according to claim 1, wherein the chlorosilane fraction containing the hydrocarbon separated in the separation step contains a hyper-hydrogenated chlorosilane.

3. The method for producing the trichlorosilane according to claim 1, comprising an STC purification step of separating the chlorinated hydrocarbon from the effluent containing STC produced in the chlorination step, wherein an STC fraction after having been purified is circulated to the hydrogenation step.

4. The method for producing the trichlorosilane according to claim 1, comprising a step of removing a donor impurity and an acceptor impurity contained in the effluent produced in the hydrogenation step, wherein the effluent after the impurities have been removed therefrom is separated into the chlorosilane fraction containing the hydrocarbon and the TCS fraction, in the separation step.

5. The method for producing the trichlorosilane according to claim 1, wherein chlorine gas is used as a chlorination agent in the chlorination step.

6. The method for producing the trichlorosilane according to claim 1, wherein a chlorination reaction to be conducted in the chlorination step is a photo-chlorination reaction.

7. The method for producing the trichlorosilane according to claim 2, wherein the hyper-hydrogenated chlorosilane is selected from the group containing of SiH₄, SiH₃Cl, SiH₂Cl₂, SiHCl₃ or mixtures thereof.

8. A method for producing polycrystalline silicon comprising a CVD step of making TCS produced in the method for producing the trichlorosilane according to claim 1 react with hydrogen to deposit polycrystalline silicon on a base material, wherein a by-product mixture which is produced in the CVD step and includes poly-silane represented by a chemical formula H_2(n+1)−

mCl_mSi_n (wherein n is an integer of 2 to 4 and m is an integer of to 2(n+1)) is chlorinated into an STC-containing substance in the chlorination step.