Recovery of silicon from kerf silicon waste
AssigneeSemlux Technologies, Inc.
InventorsAlleppey V. Hariharan, Jagannathan Ravi
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Abstract
A process for the recovery of silicon includes providing silicon-containing solids recovered from a silicon manufacturing process, said recovered silicon-containing solids being substantially free of semiconductor dopants; converting the recovered silicon-containing solids into gaseous silicon forms; subjecting to purification by minimal distillation; collecting the gaseous silicon forms as a condensed liquid of silicon-containing compounds; and utilizing the silicon-containing compounds for silicon deposition.
Claims36
A method of converting kerf silicon waste to high purity silicon comprising:
- selecting kerf silicon waste to be converted to high purity silicon, wherein the kerf silicon waste comprises silicon powder having an average particle size in the range of 1-10 microns and about 5 to 35 wt % silicon carbide impurities, wherein said silicon powder comprises less than 1 wt % metallic and nonmetallic impurities;
- converting said silicon powder into halosilanes with a mixture of hydrogen chloride and hydrogen gas between 200-250° C., wherein substantially all of said silicon carbide impurities remain unreacted;
- separating said halosilanes from said unreacted silicon carbide impurities;
- and
- converting the separated halosilanes to high purity silicon, wherein the high purity silicon is at least a photovoltaic-grade silicon.
A method of producing polysilicon comprising:
- selecting kerf silicon waste to be converted to high purity silicon, wherein the kerf silicon waste comprises silicon powders having an average particle size in the range of 1-10 microns and about 5 to 35 wt % silicon carbide impurities, wherein said silicon powder comprises less than 1 wt % metallic and nonmetallic impurities;
- converting said silicon powders into trichlorosilane with hydrogen chloride and hydrogen gas between 200-250° C., wherein substantially all of said silicon carbide impurities remain unreacted;
- separating said trichlorosilane from said silicon carbide impurities;
- and
- converting said trichlorosilane to polysilicon, wherein said polysilicon is at least photovoltaic-grade polysilicon.
Dependencies are inferred from the claim text.