An examination of the surface silicon layer of SOI substrates was made using X-ray double crystal rocking curve (XDCRC) and reflection topographic analysis (XRT). The original intent was to examine dislocations in SOI substrates-SIMOX, and BESOI (bond and etchback silicon-on-insulator). The properties of the superficial or surface silicon layer were characterized with reflection topography for the three SOI technologies, and these results were correlated with crystal quality measured by XDCRC. Reflection topography did not reveal surface imperfection, defects, or dislocations in SIMOX or BESOI, but XRT revealed the transmission of substrate strain or warpage into the surface silicon layer for all SOI samples. Rocking curves confirmed the high quality of the surface silicon layer.< >
Hole trapping, interface-state production and annealing were studied in NMOS transistors irradiated with x-rays and Co-60. Hole trapping showed a photon energy dependence that can be explained by existing models. However, interface-state generation showed an energy dependence that cannot be explained using previously available models. The results given here suggest that hole production and trapping in the oxide may involve different mechanisms than the generation of interface states. In addition, annealing of hole trapping observed in what is called "super recovery" or "rebound" was found to be reversible.
Exposure of MOSFET's to large doses of ionizing radiation causes bulk oxide charging and an increase in interface state density. The former shifts device operation thresholds. The latter degrades channel mobility gmand increases subthreshold leakage. The degree of damage introduced depends on oxide electric fields. Making gate dimensions smaller complicates modeling a number of ways. Some of these...
Annealing of defects in bulk fused silicas suggests the rate-limiting step is diffusion of molecular species. Evidence that similar processes occur in MOS devices is presented. A systematic dependence on gate size is shown.
