Elimination of stacking faults in silicon devices: a gettering process

Abstract

Described are procedures for fabricating silicon devices which prevent the formation and/or activation of stacking fault nucleation sites during high temperature processing steps, such as steam oxidation of silicon wafers. The procedures, which take place before such high temperature steps, include forming on the back surface of the wafer a stressed layer and then annealing the wafer for a time and at a temperature effective to cause the nucleation sites to diffuse to a localized region near to the back surface. Illustratively the stressed layer comprises silicon nitride or aluminum oxide. Enhanced gettering is achieved if, prior to forming the stressed layer, interfacial misfit dislocations are introduced into the back surface by, for example, diffusion of phosphorus therein. Following the gettering step(s) on the back surface, conventional procedures, such as growing epilayers and/or forming p-n junctions, are performed on the front surface of the wafer.