Co60 Radiation Effects on Dry High Pressure Oxides

Co60 gamma radiation exposure of high pressure (10 atmospheres) dry oxides at a dosage of 1×106 rad (Si) under a +10V bias, results in a -2.5 volt inversion voltage shift on 500Å oxide capacitors on (100) n-type silicon and a -4.5 volt threshold voltage shift on 650Å gate oxide SOS N-channel phosphorus doped polysilicon gate transistors. The interface state density at the Si-SiO2 interface, prior to irradiation, is between 1-2×1010 states cm-2 eV-1 at the mid-band gap. The incorporation of a post oxidation annealing procedure lowers the fixed charge density and reduces the radiation induced total charge trapping.