Recovery of silicon value from kerf silicon waste
AssigneeSemlux Newco
InventorsAlleppey V. HARIHARAN, Jagannathan RAVI
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Abstract
The present invention is for the recovery of maximum silicon value of kerf silicon waste, produced during the manufacture of silicon wafers by wire saw, diamond saw and chemical mechanical polishing, as high purity metallurgical silicon. This recovery is achieved by a process scheme that effects an initial removal of minor extrinsic metallic impurities but not the major silicon compound impurities, and followed, preferentially, by a direct metallurgical process to form elemental silicon. The recovered silicon is for use as feedstock for polysilicon manufacturing, as high purity polysilicon for PV application, and in metallurgical alloy manufacture.
Claims23
A method of converting kerf silicon waste to high purity kerf-derived Metallurgical Grade silicon comprising:
- a. providing a kerf silicon waste comprising silicon (Si) and an abrasive reducing agent selected from the group consisting of silicon carbide, carbon and mixtures thereof;
- b. introducing to the kerf silicon waste a desired amount of silicon oxide in proportion to the amount of abrasive reducing agent in the kerf silicon waste to provide a kerf material mixture;
- c. treating the kerf material mixture to reduce the silicon oxide to silicon and thereby consume the reducing agent in the kerf material mixture and provide a kerf-derived Metallurgical Grade silicon.
A method of making a silicon wafer, comprising:
- a. providing a kerf-derived silicon ingot prepared according to the method 20;
- and
- b. cutting a wafer from the ingot, wherein a wafer is obtained without an additional melt and crystal growth step.
Dependencies are inferred from the claim text.