Ion mass influence on transient enhanced diffusion and boron clustering in silicon: Deviation from the “+1” model

Abstract

Boron in silicon doping superlattices is used to trace native point defect behavior during a 790 °C, 15 min anneal following a 200 keV, 1×1013/cm2 Pb+ or 40 keV 1×1013/cm2 Si+ implant. These nonamorphizing implants lead to transient enhanced diffusion and clustering of the boron doping spikes. The enhancement in B diffusion scales sublinearly with mass of the ion implant. Clustering of the boron occurs deeper and more extensively in the Pb+-implanted sample due to greater mass of the ion. Measurement of the number of interstitials bound by extended defects after an 800 °C/10 s rapid thermal anneal confirm that the Pb+ implant has “+4.5” of the implant dose bound by extended defects, compared to “+0.6” in the Si+ implant for the same anneal. Both of these results indicate that the “+1” model is not valid for heavy mass ion implants.