Method and system for forming a silicon ingot using a low-grade silicon feedstock

摘要

Techniques for the formation of a silicon ingot using a low-grade silicon feedstock include forming within a crucible device a molten silicon from a low-grade silicon feedstock and performing a directional solidification of the molten silicon to form a silicon ingot within the crucible device. The directional solidification forms a generally solidified quantity of silicon and a generally molten quantity of silicon. The method and system include removing from the crucible device at least a portion of the generally molten quantity of silicon while retaining within the crucible device the generally solidified quantity of silicon. Controlling the directional solidification of the generally solidified quantity of silicon, while removing the more contaminated molten silicon, results in a silicon ingot possessing a generally higher grade of silicon than the low-grade silicon feedstock.

主权项

1. A system for forming a silicon ingot using a low-grade silicon feedstock, said silicon ingot comprising higher grade silicon than said low-grade silicon feedstock, comprising:
a crucible device for receiving and heating a low-grade silicon feedstock and for forming a molten silicon in response to the heating; temperature control means for performing a directional solidification of the molten silicon to form a silicon ingot within the crucible device, the temperature control means configured to form the silicon ingot from the bottom of the crucible device toward the top to form a solidified quantity of silicon and a molten quantity of silicon on top of the solidified quantity of silicon, wherein the temperature control means is configured so that the directional solidification increases the height of the combined solidified quantity of silicon and the molten quantity of silicon within the crucible device; a pathway associated with the crucible device for removing from the crucible device at least a portion of the molten quantity of silicon while retaining within the crucible device the solidified quantity of silicon by flowing at least the portion of the molten quantity of silicon from the crucible device via the pathway, wherein the pathway is positioned at a height so that the increase in height due to the directional solidification allows at least the portion of the molten quantity of silicon to reach the height of the pathway.