Voltage pulse stress effect on gate stack TDDB distributions at nanometric scale: Consequence on aging by ESD

The effects of a voltage pulse stress on time to breakdown and breakdown voltage distributions of a 1.4nm thick SiON layer are investigated at nanometric scale using an atomic force microscope in conduction mode under ultra-high vacuum. Thanks to the reduced tip/sample contact area, a large window of voltage pulse amplitude and length is allowed. It is found that the pre-stress pulse does impact the slope of the cumulative failure distribution but has no effect on the voltage acceleration factor. Using this assumption an extrapolation formula is given to predict the decrease of the time to breakdown as a function of the pre-stress pulse parameters.