The role of localized states in the degradation of thin gate oxides

A model is proposed to address the effects of oxide electric field and anode bias, as well as the role of hydrogen, in the trap generation process. The oxide wear-out phenomenon is considered as a multi-step process initiated by the capture of injected electrons by localized states in SiO2. The captured electrons significantly weaken the corresponding Si-O bond, which becomes unstable with respect to the applied electric field and temperature. The hydrogen present in the oxide (due to the anode hydrogen release process) prevents restoration of the broken bonds and leads to the generation of neutral E' centers. The model describes the charge-to-breakdown dependence on the electron energy, electric field, temperature, and oxide thickness. (C) 2003 Elsevier B.V. All rights reserved.