Patent ID: 8547121
Filing Date: 2013-10-01
Classification: C01B,Y10T

Abstract:
1. A control method for evaluating the quality of a UMG-Si feedstock, the method comprising the steps of: performing a directional solidification of molten upgraded metallurgical-grade silicon (UMG-Si) from a UMG-Si feedstock batch to form a silicon test ingot; measuring the resistivity from top to bottom of said silicon test ingot; mapping the resistivity profile of said silicon test ingot; calculating the phosphorus and boron concentrations of said UMG-Si feedstock batch based on said resistivity profile of said silicon test ingot; and determining, based on the resistivity profile of said silicon test ingot, an amount of at least one co-dopant for use in said UMG-Si feedstock batch for increasing an ingot yield and producing an improved resistivity profile by directional solidification.