Mechanism for the reduction of interstitial supersaturations in MeV-implanted silicon

We demonstrate that the excess vacancies induced by a 1 MeV Si implant redu ce the excess interstitials generated by a 40 keV Si implant during thermal annealing when these two implants are superimposed in silicon. It is shown that this previously observed reduction is dominated by vacancy annihilati on and not by gettering to deeper interstitial-type extended defects. Inter stitial supersaturations were measured using B doping superlattices (DSL) g rown on a silicon-on-insulator (SOI) substrate. Implanting MeV and keV Si i ons into the B DSL/SOI structure eliminated the B transient enhanced diffus ion normally associated with the keV implant. The buried SiO2 layer in the SOI substrate isolates the deep interstitials-type extended defects of the MeV implant, thereby eliminating the possibility that these defects getter the interstitial excess induced by the keV Si implant. (C) 1999 American In stitute of Physics. [S0003-6951(99)03309-4].