Polycrystalline silicon rod and process for production thereof

• US 9,481,578 B2
• Filed: 02/27/2015
• Issued: 11/01/2016
• Est. Priority Date: 05/07/2012
• Status: Active Grant

• Current Assignee: Wacker Chemie AG (Dr. Alexander Wacker Familiengesellschaft Mit Beschrã¤Nkter Haftung)
• Original Assignee: Wacker Chemie AG (Dr. Alexander Wacker Familiengesellschaft Mit Beschrã¤Nkter Haftung)
• Inventors: Weber, Martin, Dornberger, Erich, Kerscher, Michael, Kraus, Heinz, Pech, Reiner
• Primary Examiner(s): LANGMAN, JONATHAN C
• Application Number:
  US14/633,312
• Publication Number:
  US 20150166351A1
• Time in Patent Office: 613 Days
• US Class Current: 1/1
• CPC Class Codes: B02C 19/0056 specially adapted for specific materials not otherwise provided for
• CPC Class Codes: C01B 33/02 Silicon forming single crystals or homogeneous polycrystalline material with defined structure C30B
• CPC Class Codes: C01B 33/029 by decomposition of monosilane
• 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: C23C 16/24 Deposition of silicon only
• CPC Class Codes: C23C 16/4418 Methods for making free-standing articles C23C16/01 takes precedence
• CPC Class Codes: C30B 28/14 by chemical reaction of reactive gases
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: Y10T 428/12479 Porous [e.g., foamed, spongy, cracked, etc.]

Abstract

The invention provides a polycrystalline silicon rod having a total diameter of at least 150 mm, including a core A having a porosity of 0 to less than 0.01 around a thin rod, and at least two subsequent regions B and C which differ in porosity by a factor of 1.7 to 23, the outer region C being less porous than region B.

Claims

1. A process for producing polycrystalline silicon chunks, said process comprising comminuting a polycrystalline silicon rod having a total diameter of at least 150 mm, wherein the polycrystalline silicon rod comprises:

a core A having a porosity of 0 to less than 0.01,

which is around a thin rod;

a region B around core A; and

a region C around region B,

wherein regions B and C differ in porosity by a factor of 1.7 to 23, and region C is less porous than region B.

2. The process of claim 1, wherein core A of the polycrystalline silicon rod extends up to a diameter of not more than 60 mm.

3. The process of claim 1, wherein region B of the polycrystalline silicon rod has a porosity of 0.06 to 0.23 and extends over a region of 15% of the total diameter to a maximum of 90% of the total diameter.

4. The process of claim 1, wherein region C of the polycrystalline silicon rod has a porosity of 0.01 to 0.1 and extends over a region of at least 50% of the total diameter to a maximum of 100% of the total diameter, region C having a lower porosity than region B.

5. The process of claim 1, wherein the polycrystalline silicon rod further comprises a layer Z around region C, which has a porosity of 0 to less than 0.01 and extends over a region of at least 90% of the total diameter to 100% of the total diameter.

6. The process of claim 2, wherein region B of the polycrystalline silicon rod has a porosity of 0.06 to 0.23 and extends over a region of 15% of the total diameter to a maximum of 90% of the total diameter.

7. The process of claim 6, wherein region C of the polycrystalline silicon rod has a porosity of 0.01 to 0.1 and extends over a region of at least 50% of the total diameter to a maximum of 100% of the total diameter, region C having a lower porosity than region B.

8. The process of claim 7, wherein the polycrystalline silicon rod further comprises a layer Z around region C, which has a porosity of 0 to less than 0.01 and extends over a region of at least 90% of the total diameter to 100% of the total diameter.