The effect of reactive plasma etching on the transient enhanced diffusion of boron in silicon

Silicon wafers oxidized and stripped by reactive plasma etching were implanted with 5 keV B, 1 x 10(13)/cm(2). The transient enhanced diffusion of B, usually observed in samples which receive such implants over characteristic time scales, is strongly retarded in these plasma etched samples upon annealing at 800, 900, or 1000 degrees C, as measured by secondary ions mass spectrometry. These results suggest that the defects generated by the plasma etching procedure in the near surface region, represent an efficient sink against the flow of interstitials which cause the transient enhanced diffusion. A slow release of interstitials from this trapping immobile background occurs with characteristic time scales which are, however, a factor of 30-60 times higher than the usual lifetimes of transient diffusion. This release is characterized by an activation energy of 2.4 eV, These data are reported and their implication on shallow junction formation are discussed. (C) 1997 American Institute of Physics