THE EFFECT OF THE BORON DOPING LEVEL ON THE THERMAL-BEHAVIOR OF END-OF-RANGE DEFECTS IN SILICON

The effect of the doping level on the formation and growth of end-of-r ange (EOR) defects is studied. Transmission electron microscopy observ ations have been performed on boron doped Si wafers (from 10(15) to 10 (20) at/cm(3)) preamorphized with germanium and subjected to rapid the rmal annealing. When increasing the doping level up to a few 10(18) at /cm(3), a delay in the coarsening process encountered by the loops is observed while above this threshold the EOR defects quickly disappear. These results are interpreted by considering three possibly concomita nt phenomena: the formation of boron/Si-interstitial clusters, the get tering of boron at the loop periphery, and a change from the intrinsic to the extrinsic regime for self-diffusion. Moreover, an estimate of the effective trapping efficiency of boron is reached and gives about 1 +/- 0.3 Si interstitial per boron atom, a value consistent with the one obtained from studies of B transient enhanced diffusion. (C) 1997 American Institute of Physics.