Oxide trapped charge and time to breakdown of pulsed current measurements in the Fowler-Nordheim regime

In this research work, the trapped oxide charge (Q_ox) and the time to breakdown (t_bd) of a thin dielectric (SiO₂) layer were investigated using a constant current with low current characterisation pulses. The results imply that the stress method of DiMaria et al. (1976) is not suitable for a quantitative determination of Q_ox, or at least must be used very carefully in order to avoid crucial mistakes. For stress interval t_high<1 s t_bd decreases and V-t curves deviate, in contradiction to common understanding of a t_bd increase with pulsed measurements. The voltage transients at the beginning of the low current step are the reason for these observations. When the oxide does not reach a steady-state because of fast switching from high to low currents the measured data deviate significantly from expected results