Gettering of iron impurities in p/p+ epitaxial silicon wafers with heavily boron-doped substrates

Abstract

We studied gettering effects in p/p+ silicon epitaxial wafers that have no dislocations near the epi/sub interface and oxygen precipitates inside the p+ substrate. The wafers were contaminated with high- and low-level Fe surface concentrations to clarify the relationship between gettering effects and Fe concentration. After annealing at 1000 °C for 60 min followed by quenching, the p/p+ epitaxial wafers showed the same gettering effect independent of the Fe contamination level. The intrinsic gettered reference wafers, however, did not show the gettering effect because Fe impurities do not supersaturate at 1000 °C. We concluded that the gettering effect of Fe in the p/p+ epitaxial wafers is due to the difference in solubility between the p epitaxial layer and the p+ substrate.