Gettering of Co in Si by High Energy B Ion-Implantation and by P/p+ Epitaxial Si

Detection and gettering of Co contamination in processed Si is an important issue in intregrated circuit fabrication. In this work, Co was intentionally introduced into Si by ion implantation, and its diffusion monitored by secondary ion mass spectroscopy. The surface layer recombination lifetime in p/p+ epitaxial Si is unaffected by the Co at doses of 1x10 sup (11) cm sup (-2) or 1x10 sup (12) cm sup (-2). In the case of 2.5 MeV, 4x10 sup (14) B/cm sup 2 ion implanted bulk Si, two mechanisms for Co redistribution during high temperature furnace, 900C, 30min., processing are evident. First, regions of high boron concentation provide gettering sites for Co contamination. Second, the final distribution of Co in Si reflects ion-implantation induced defect evolution during annealing. Both mechanisms will operate during device processing and will control the effect of the metal on the electrical properties of the Si.