Measurement and statistical analysis of single trap current-voltage characteristics in ultrathin SiON

This work discusses the discrete nature of stress-induced leakage current (SILC) in small samples with ultrathin SiON. We isolate the current-voltage characteristics of single-trap leakage paths and we evaluate their statistical properties. Each leakage path can, to a first order approximation, be described by the gate voltage at which it becomes conducting and by its conductivity at a fixed voltage. From a statistical study of these two parameters, we propose a model for the spatial and energetic distribution of the traps causing the SILC. The trap generation rate is shown to be higher than stress-induced leakage current generation rate due to switching behavior of the leakage paths. The voltage acceleration of the trap generation process corresponds to that of dielectric breakdown if progressive wearout effects are not taken into account.