EVALUATION OF SILICON-ON-INSULATOR SUBSTRATES USING PHOTOCONDUCTIVE FREQUENCY-RESOLVED SPECTROSCOPY

We describe here the application of photoconductive frequency resolved spectroscopy to determine excess carrier lifetime distributions and c arrier kinetics in SIMOX (separation by implanting oxygen) material. I n order to evaluate the influence of the implant and anneal processes on the quality of the silicon overlayer we have also analyzed unproces sed bulk silicon, high temperature annealed bulk silicon and as-implan ted SIMOX material. Our photoconductive frequency resolved spectroscop y results reveal that the SIMOX layers have a higher density of defect s than standard device quality silicon substrates. Characteristic para meters of the dominant traps in these materials have been obtained fro m Arrhenius plots of the lifetime distributions. The defects found in these SIMOX layers are shown to be formed during the high temperature anneal stage of the material production.