Effect of implantation current density and anneal time on the microstructure of SIMOX

We have studied two temperature-related effects in the fabrication of high quality SIMOX materials: 1) the large ion beam induced rise in sample temperature during oxygen implantation, and 2) the time dependence of the high temperature annealing required after implantation. Oxygen ions were implanted at 160 keV into (100) Si wafers to a total dose of 4 × 10 17 O + cm 2 with current densities from 10 to 60 μA/cm2. The samples were annealed at 1300°C for 0 to 6 h. The microstructures were examined using cross-sectional transmission electron microscopy. With a current density of 60 μA/cm2, permanent damage occurred in the top Si layer. No effects were observed after post-implantation annealing for samples implanted with 10–50 μA/cm2 current densities. Oxygen precipitates were found to grow and coarsen with increasing anneal time, finally becoming a non-uniform buried oxide layer. Oxide layer formation is an oxygen diffusion controlled process.