Gettering issues using MeV ion implantation

MeV implantation has generated interest as a gettering option in silicon since it was established that under the appropriate conditions of irradiation fluence, substrate oxygen content, and annealing treatment, at least two distinct regions, denoted as Rp and Rp/2, getter impurities (M. Tamura, T. Ando, O.K., Nucl. Instrum. Methods Phys. Res. B 59/60 (1991) 572; A. Agarwal, K. Christensen, D. Venables, D.M. Maher, G.A. Rozgonyi, Appl. Phys. Lett. 69 (1996) 3899). In the present work we report on the thermal stability of Fe gettered at Rp due to MeV ion implantation-induced dislocation loops in Fe contaminated CZ Si wafers, and an activation energy for the release of gettered Fe of 0.80 eV. It has also been determined that, the gettering mechanism in the Rp/2 region in epitaxial Si for high MeV ion doses (≈5×1015 Ge cm−2) is vacancy-related, since TEM analysis revealed 4–11-nm diameter voids. Under the annealing conditions studied, these voids were found to be more efficient at Fe capture than Rp defects.