Patent ID: 7651566
Filing Date: 2010-01-26
Classification: C30B,Y10T

Abstract:
1. A method for controlling resistivity in the formation of a silicon ingot, comprising the steps of: preparing a compensated, upgraded metallurgical silicon feedstock for being melted to form a silicon melt, said compensated, upgraded metallurgical silicon feedstock comprising a predominantly p-type semiconductor; assessing quantitatively the relative concentrations of boron and phosphorus in said compensated, upgraded metallurgical silicon feedstock; adding to said compensated, upgraded metallurgical silicon feedstock a greater-than-zero quantity of an element from the group consisting of aluminum, gallium, mixtures of aluminum and gallium, or other Group III elements, wherein said quantitatively assessed relative concentrations of boron and phosphorous determine said greater-than-zero quantity; melting said upgraded metallurgical silicon feedstock and said greater-than-zero quantity of said element to form a molten silicon solution including said greater-than-zero quantity of said element; and performing a directional solidification of said molten silicon solution for forming a silicon ingot and, by virtue of said adding said greater-than-zero quantity of said element, suppressing the transition of said silicon ingot to n-type material by virtue of reducing the effect of differing boron and phosphorous segregation coefficients.