The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 2010
Filed:
Jan. 12, 2009
Karl Hesse, Burghausen, DE;
Franz Schreieder, Tann, DE;
Karl Hesse, Burghausen, DE;
Franz Schreieder, Tann, DE;
Wacker Chemie, Munich, DE;
Abstract
Polycrystalline silicon is prepared by thermally decomposing a reaction gas comprising hydrogen and a silicon-containing gas in a reaction chamber containing heated silicon, depositing additional silicon thereon, and forming an offgas; and separating the offgas into a first fraction comprising trichlorosilane and lower boiling chlorosilanes, and a second offgas fraction comprising components having a higher boiling point than trichlorosilane; recycling the first offgas fraction to the reaction gas of a polycrystalline silicon deposition; and separating the second offgas fraction into tetrachlorosilane and a high boiler fraction of high boilers, optionally also containing some tetrachlorosilane, and supplying the high boiler fraction to the reaction gas of a silicon deposition and heating the reaction gas to a temperature which ensures that the high boiler fraction is present in gaseous form on entry into the reaction chamber of the deposition reactor.