Oxide thickness dependence of high-energy-electron-, VUV-, and corona-induced charge in MOS capacitors

The radiation-induced flatband voltage shift of MOS capacitors using dry-O2-grown SiO2 is shown to vary as the square of oxide thickness for penetrating 1-MeV electron radiation and linearly with oxide thickness for nonpenetrating 10.2-eV photon radiation. Corona discharge experiments on unmetallized portions of the same oxidized silicon wafers also show a flatband voltage shift linearly dependent upon oxide thickness. These experiments provide strong evidence to support a simple generation, transport, and trapping model for radiation charging of SiO2. The results also show that for dry oxides the density of trapped holes near the Si-SiO2 interface is indepenent of oxidation time