A study of point defect detectors created by Si and Ge implantation

Abstract

Short-time/low-temperature thermal oxidation is known to lead to point defect perturbations in silicon. This study investigates the interaction between oxidation-induced point defects and type II dislocation loops intentionally introduced in silicon via ion implantation. The type II (end-of-range) dislocation loops were introduced via implantation of either Si+ ions at 50 keV or Ge+ ions at 100 keV into <100≳Si wafers at doses ranging from 2×1015 to 1×1016/cm 2. Furnace anneals were done at 900°C for times between 30 min and 4 h in both a dry oxygen and nitrogen ambient. The change in atom concentration bound by dislocation loops as a result of oxidation was measured by plan-view transmission electron microscopy. The results show type II dislocation loops can be used as point defect detectors. When Ge+ implantation was used to form the dislocation loops, a decrease in trapped atom concentration relative to the control was observed upon oxidation. These results imply that oxidation of high dose Ge+ implanted silicon results either in vacancy injection or provides an excellent sink for interstitials. It is also shown that when Si+ implantation is used to form the dislocation loops, the measured net interstitial flux trapped by dislocation loops is linearly proportional to the total supersaturation of interstitials determined by oxidation-enhanced diffusion studies done by Packan and Plummer [J. Appl. Phys. 68, 4327 (1990)].