PRODUCTION OF POLYCRYSTALLINE SILICON IN SUBSTANTIALLY CLOSED-LOOP SYSTEMS

• US 20130236367A1
• Filed: 04/26/2013
• Published: 09/12/2013
• Est. Priority Date: 10/22/2010
• Status: Active Grant

• Current Assignee: Corner Star Limited (GCL Technology Holdings Ltd.)
• Original Assignee: SunEdison, Inc.
• Inventors: Bhusarapu, Satish, Huang, Yue, Gupta, Puneet
• Granted Patent: US 9,394,180 B2
• Time in Patent Office: Days
• US Class Current: 422/144
• CPC Class Codes: B01J 8/24 according to "fluidised-bed" technique B01J8/20 takes precedence
• 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 33/039 by conversion of the silicon into a compound, optional purification of the compound, and reconversion into silicon
• CPC Class Codes: C01B 33/10742 prepared by hydrochlorination of silicon or of a silicon-containing material
• CPC Class Codes: C01B 33/10763 from silicon
• CPC Class Codes: C01B 33/10773 Halogenated silanes obtained by disproportionation and molecular rearrangement of halogenated silanes

Abstract

Production of polycrystalline silicon in a substantially closed-loop process is disclosed. The processes generally include decomposition of trichlorosilane produced from metallurgical grade silicon.

Claims

1. A system for producing polycrystalline silicon by decomposition of trichlorosilane, the system being substantially closed-loop with respect to trichlorosilane, the system comprising:

a chlorination reactor in which hydrogen chloride is contacted with silicon to produce trichlorosilane and silicon tetrachloride;

a fluidized bed reactor in which trichlorosilane is decomposed to produce polycrystalline silicon; and

a hydrogenation reactor in which silicon tetrachloride and hydrogen are introduced without silicon to produce trichlorosilane.

2. The system as set forth in claim 1 comprising:

a conveying apparatus for conveying trichlorosilane from the hydrogenation reactor to the fluidized bed reactor; and

a conveying apparatus for conveying trichlorosilane from the chlorination reactor to the fluidized bed reactor.

3. The system as set forth in claim 1 comprising a purification system to which trichlorosilane and silicon tetrachloride are introduced to separate trichlorosilane and silicon tetrachloride.

4. The system as set forth in claim 3 comprising:

a conveying apparatus for conveying trichlorosilane from the purification system to the fluidized bed reactor; and

a conveying apparatus for conveying silicon tetrachloride from the purification system to the hydrogenation reactor.

5. The system as set forth in claim 3 comprising an effluent gas separator to which effluent gas from the fluidized bed reactor is introduced, the effluent gas comprising silicon tetrachloride, hydrogen and unreacted trichlorosilane, wherein the effluent gas separator separates hydrogen from trichlorosilane and silicon tetrachloride.

6. The system as set forth in claim 5 comprising a conveying apparatus for conveying trichlorosilane and silicon tetrachloride from the effluent gas separator to the purification system.

7. The system as set forth in claim 3 comprising a hydrogenated gas separator to which hydrogenated gas from the hydrogenation reactor is introduced, the hydrogenated gas comprising trichlorosilane, hydrogen chloride, unreacted hydrogen and unreacted silicon tetrachloride, wherein the hydrogenated gas separator separates trichlorosilane and unreacted silicon tetrachloride from hydrogen and unreacted hydrogen chloride.

8. The system as set forth in claim 7 comprising a conveying apparatus for conveying trichlorosilane and unreacted silicon tetrachloride to the purification system.

9. The system as set forth in claim 7 comprising a separation system to which hydrogen and hydrogen chloride from the hydrogenated gas separator are introduced to separate hydrogen and hydrogen chloride.

10. The system as set forth in claim 9 comprising:

a conveying apparatus for conveying hydrogen chloride from the separation system to the chlorination reactor; and

a conveying apparatus for conveying hydrogen from the separation system to at least one of the fluidized bed reactor and the hydrogenation reactor.

11. A system for producing polycrystalline silicon by decomposition of trichlorosilane, the system being substantially closed-loop with respect to trichlorosilane, the system comprising:

a chlorination reactor in which hydrogen chloride is contacted with silicon to produce trichlorosilane and silicon tetrachloride;

a first fluidized bed reactor in which trichlorosilane is decomposed to produce polycrystalline silicon; and

a second fluidized bed reactor in which silicon tetrachloride is contacted with hydrogen and particulate silicon to produce trichlorosilane.

12. The system as set forth in claim 11 comprising a conveying apparatus for conveying trichlorosilane from the chlorination reactor to the first fluidized bed reactor.

13. The system as set forth in claim 11 comprising a purification system to which trichlorosilane and silicon tetrachloride are introduced to separate trichlorosilane and silicon tetrachloride.

14. The system as set forth in claim 13 comprising:

a conveying apparatus for conveying trichlorosilane from the purification system to the first fluidized bed reactor; and

a conveying apparatus for conveying silicon tetrachloride from the purification system to the second fluidized bed reactor.

15. The system as set forth in claim 13 comprising a first effluent gas separator to which effluent gas from the first fluidized bed reactor is introduced, the effluent gas comprising silicon tetrachloride, hydrogen and unreacted trichlorosilane, wherein the first effluent gas separator separates hydrogen from trichlorosilane and silicon tetrachloride.

16. The system as set forth in claim 15 comprising a conveying apparatus for conveying trichlorosilane and silicon tetrachloride from the first effluent gas separator to the purification system.

17. The system as set forth in claim 13 comprising a second effluent gas separator system to which a second effluent gas from the second fluidized bed reactor is introduced, the second effluent gas comprising trichlorosilane, unreacted trichlorosilane and unreacted hydrogen, wherein the second effluent gas separator separates trichlorosilane and unreacted silicon tetrachloride from unreacted hydrogen.

18. The system as set forth in claim 17 comprising a conveying apparatus for conveying trichlorosilane and unreacted silicon tetrachloride to the purification system.

19. The system as set forth in claim 17 comprising a separation system to which hydrogen and hydrogen chloride from the second effluent gas separator are introduced to separate hydrogen and hydrogen chloride.

20. The system as set forth in claim 19 comprising:

a conveying apparatus for conveying hydrogen chloride from the separation system to the chlorination reactor; and

a conveying apparatus for conveying hydrogen from the separation system to at least one of the first fluidized bed reactor and the second fluidized bed reactor.

21. The system as set forth in claim 11 wherein the chlorination reactor is a fluidized bed reactor.