Oxygen implanted silicon investigated by positron annihilation spectroscopy

In the manufacture of SIMOX a Si wafer is implanted with 1.7 x 10(18). 180 keV oxygen ions. After implantation the wafer is annealed at 1350 degrees C . This process creates a top layer of silicon, which almost has the quality of bulk silicon, and an insulating layer of buried oxide (BOX), that separ ates the top layer from the Si wafer, Positron annihilation techniques are very sensitive for the open-volume defects produced during the implantation . The Doppler broadening of the annihilation radiation technique was applie d to investigate the effect of dose variations and anneal temperature, The positron annihilation results show that the top silicon layer in SIMOX stil l contains small vacancy-oxygen clusters which cannot be observed with TEM. (C) 1998 Elsevier Science B.V. All rights reserved.