CORE WIRE HOLDER FOR PRODUCING POLYCRYSTALLINE SILICON AND METHOD FOR PRODUCING POLYCRYSTALLINE SILICON

• US 20120201976A1
• Filed: 07/27/2010
• Published: 08/09/2012
• Est. Priority Date: 10/14/2009
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Netsu, Shigeyoshi, Kurotani, Shinichi, Oguro, Kyoji, Kume, Fumitaka
• Granted Patent: US 8,793,853 B2
• Time in Patent Office: Days
• US Class Current: 427/585
• 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: Y10T 29/53796 Puller or pusher means, contained force multiplying operator
• CPC Class Codes: Y10T 29/53961 with work-holder for assembly

Abstract

One end side of a core wire holder 20 is formed into a shape of a truncated cone and has an inclined surface. In the end portion, an opening 22 is provided, and a hollow portion 21 is formed, a silicon core wire 5 being inserted into the hollow portion 21 and held therein. On the surface of the silicon core wire 5, polycrystalline silicon 6 is vapor deposited by the Siemens method to produce a polycrystalline silicon rod. On the inclined surface of the truncated cone portion in the vicinity of the opening 22, as a thermal insulating layer, annular slits 23a to 23c are formed from an outer circumferential surface in the vicinity of the opening toward the hollow portion 21. The annular slit acts as a thermal insulating portion, and suppresses escape of the heat to heat the one end side of the core wire holder 20.

Claims

1. A core wire holder comprising:

a thermal insulating portion provided between one end and the other end of the core wire holder, wherein an opening of a hollow portion into which a silicon core wire is inserted is provided in the one end, and the other end is a contact portion with a metal electrode for flowing a current to the silicon core wire wherein the core wire holder is suitable for use in producing polycrystalline silicon by Siemens method.

2. The core wire holder according to claim 1, wherein the core wire holder is a carbon electrode made of graphite.

3. The core wire holder according to claim 1, wherein the thermal insulating portion comprises an annular slit formed from an outer circumferential surface near the opening of the hollow portion.

4. The core wire holder according to claim 3, wherein a depth of the annular slit is not less than 70% and less than 100% of a thickness of the core wire holder in a region in which the annular slit is formed.

5. The core wire holder according to claim 3, wherein a depth of the annular slit is not less than 90% and less than 100% of a thickness of the core wire holder in a region in which the annular slit is formed.

6. The core wire holder according to claim 3, wherein a distance between an inner circumferential surface of the annular slit and an outer circumferential surface of the silicon core wire is not less than 0.1 mm.

7. The core wire holder according to claim 3, wherein a width of the annular slit is not less than 0.5 mm.

8. The core wire holder according to claim 3, wherein the one end is formed into a shape of a truncated cone, and the annular slit is formed on an inclined surface of the truncated cone.

9. The core wire holder according to claim 3, wherein the annular slit is filled with an insulating material having a thermal conductivity less than that of the core wire holder.

10. The core wire holder according to claim 1, wherein a thermal conductivity of the core wire holder is not more than 145 W/m·

K.

11. A method for producing polycrystalline silicon, the method comprising:

supplying a current to the core wire holder of claim 3 such that a current density in a cross section of the annular slit forming portion is not less than 0.05 A/mm² and not more than 4.9 A/mm² when vapor deposition of polycrystalline silicon is started.

12. The core wire holder according to claim 2, wherein the thermal insulating portion comprises an annular slit formed from an outer circumferential surface near the opening of the hollow portion.

13. The core wire holder according to claim 2, wherein a thermal conductivity of the core wire holder is not more than 145 W/m·

K.

14. The core wire holder according to claim 4, wherein a distance between an inner circumferential surface of the annular slit and an outer circumferential surface of the silicon core wire is not less than 0.1 mm.

15. The core wire holder according to claim 5, wherein a distance between an inner circumferential surface of the annular slit and an outer circumferential surface of the silicon core wire is not less than 0.1 mm.

16. The core wire holder according to claim 14, wherein a width of the annular slit is not less than 0.5 mm.

17. The core wire holder according to claim 15, wherein a width of the annular slit is not less than 0.5 mm.

18. The core wire holder according to claim 16, wherein the one end side is formed into a shape of a truncated cone, and the annular slit is formed on an inclined surface of the truncated cone.

19. The core wire holder according to claim 17, wherein the one end side is formed into a shape of a truncated cone, and the annular slit is formed on an inclined surface of the truncated cone.

20. The core wire holder according to claim 12, wherein the annular slit is filled with an insulating material having a thermal conductivity less than that of the core wire holder.