Radiation-Induced Perturbations of the Electrical Properties of the Silicon-Silicon Dioxide Interface

Interface-state densities and MOS transistor characteristics dependent upon such states have been studied as a function of radiation dose and type. Special MOS devices possessing doped silicon-dioxide layers as well as undoped "control" devices have been utilized. Infrared absorption measurements were performed on silicon-dioxide samples before and after exposure to radiation, as well as for doped and undoped samples. A model based on structural modifications of the silicon-dioxide-films is proposed for the build-up of interface-states resulting from exposure to radiation. It has been found that with the proper doping of the silicon-dioxide films, the build-up of such states can be reduced. Using such doped gate-dielectrics, planar semiconductor devices much less sensitive to radiation have been fabricated.