Acceleration factors and mechanistic study of progressive breakdown in small area ultra-thin gate oxides

Two post soft breakdown modes are studied: one in which the conducting filament is stable until hard breakdown occurs and one in which the filament continually degrades with time. Acceleration factors are different for each mode, indicating different physical mechanisms. The results suggest that the "hardness" of the first breakdown influences the residual time distribution of the following hard breakdown. Tunneling current appears to be the driving force for both modes.