CHARGE TRAPPING VERSUS BURIED OXIDE THICKNESS FOR SIMOX STRUCTURES

Radiation induced charge trapping versus Buried-Oxide (BOX) thickness on various Separation-by-IMplantation-of-OXygen (SIMOX) buried oxides has been determined. An inflection point has been observed in the volt age shift versus buried oxide thickness relationship. As such, the rad iation-induced voltage shifts for thin buried-oxides are greater than what could be expected from a simple square-law relationship. However, for irradiation applied fields higher than that of typical buried-oxi de fringing fields the thickness relationship obeys a square-law. Thes e results can be explained by the location and magnitude of the radiat ion induced oxide charge centroid and its relationship to the BOX thic kness. The location of the centroid for trapped positive charge is dep endant on the radiation-induced hole mobility, which is related to SIM OX processing, as well as on geometry and charge saturation.