Method for producing trichlorosilane and method for producing polycrystalline silicon

• US 7,790,132 B2
• Filed: 09/03/2008
• Issued: 09/07/2010
• 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
• Primary Examiner(s): Vanoy; Timothy C
• Assistant Examiner(s): Liao; Diana J
• Application Number:
  US12/203,395
• Publication Number:
  US 20090060820A1
• Time in Patent Office: 734 Days
• Field of Search: 423/324, 423/341, 423/342, 423/348, 423/349, 423/240.R, 203/29
• 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:

reacting tetrachlorosilane with hydrogen to form trichlorosilane by hydrogenation of tetrachlorosilane;

separating an effluent produced during said reacting into a chlorosilane fraction and a trichlorosilane fraction, said chlorosilane fraction comprising a hydrocarbon and hyper-hydrogenated chlorosilane;

chlorinating said chlorosilane fraction by reaction with a chlorinating agent to form a fraction comprising chlorinated hydrocarbon and tetrachlorosilane;

upon said chlorinating, recycling the tetrachlorosilane produced by said chlorinating into said reacting; and

upon said chlorinating, separating the tetrachlorosilane produced during said chlorinating from the chlorinated hydrocarbon.

2. The method according to claim 1, further comprising removing a donor impurity and an acceptor impurity present in the effluent prior to said separating.

3. The method according to claim 1, wherein said chlorination agent is chlorine gas.

4. The method according to claim 1, wherein said chlorinating occurs by photo-chlorinating the hydrocarbon and the hyper-hydrogenated chlorosilane.

5. The method according to claim 1, wherein the hyper-hydrogenated chlorosilane is selected from the group consisting of SiH₄, SiH₃Cl, SiH₂Cl₂, SiHCl₃, and a mixture thereof.

6. A method for producing polycrystalline silicon, comprising

reacting trichlorosilane produced during the method according to claim 1 with hydrogen to deposit polycrystalline silicon on a base material, and

further chlorinating poly-silane represented by a chemical formula:

H<sub>2(n+1)−

m</sub>Cl_mSi_n

during said chlorinating,

wherein n is an integer of 2 to 4 and m is an integer of 0 to 2(n+1).

7. The method according to claim 1, wherein said reacting occurs at a temperature of from 400 to 600°

C.

8. The method according to claim 1, further comprising supplying silicon during said reacting.

9. The method according to claim 1, wherein said chlorinating occurs in a liquid phase at a temperature of from 20 to 100°

C.

10. The method according to claim 1, wherein said chlorinating occurs in a gas phase at a temperature of 400°

C. or greater.

11. The method according to claim 1, wherein the hydrocarbon has 5 carbon atoms.

12. The method according to claim 1, wherein the hydrocarbon is isopentane having a boiling point of 30°

C., which is close to the known boiling point of trichlorosilane.

13. The method according to claim 1, wherein said chlorinated hydrocarbon comprises at least one of I and II

14. The method according to claim 1, wherein said hydrocarbon is present in an amount of at least 5 ppm prior to said chlorinating.

15. The method according to claim 1, wherein said fraction comprising chlorinated hydrocarbon and tetrachlorosilane of said chlorinating comprises at least 99.895 wt % of tetrachlorosilane.

16. The method according to claim 1, wherein said reacting occurs in the presence of a fluidized bed.