Microdefects and self-interstitial diffusion in crystalline silicon

摘要

In this thesis, a study is presented of D-defects and self-interstitial diffusion in silicon using Li ion (Li(sup +)) drifting in an electric field and transmission electron microscopy (TEM). Obstruction of Li(sup +) drifting has been found in wafers from certain but not all FZ p-type Si. Incomplete Li(sup +) drifting always occurs in the central region of the wafers. This work established that interstitial oxygen is not responsible for hindering Li(sup +) drifting. TEM was performed on a samples from the partially Li(sup +) drifted area and compared to regions without D-defects. Precipitates were found only in the region containing D-defects that had partially Li(sup +) drifted. This result indicates D-defects are responsible for the precipitation that halts the Li(sup +) drift process. Nitrogen (N) doping has been shown to eliminate D-defects as measured by conventional techniques. Li(sup +) drifting and D-defects provide a useful means to study Si self-interstitial diffusion. The process modeling program SUPREM-IV was used to simulate the results of Si self-interstitial diffusion obtained from Li(sup +) drifting experiments. Anomalous results from the Si self-interstitial diffusion experiments forced a re-examination of the possibility of thermal dissociation of D-defects. Thermal annealing experiments that were performed support this possibility. A review of the current literature illustrates the need for more research on the effects of thermal processing on FZ Si to understand the dissolution kinetics of D- defects.