Snapback behavior of the postbreakdown I–V characteristics in ultrathin SiO2 films

With the I–V measurement technique that forced a current to an ultrathin gate oxide and measured the voltage drop, a snapback phenomenon, i.e., the gate oxide was switched from a higher-impedance state to a lower-impedance state suddenly, was observed during the postbreakdown I–V measurement. The snapback could be triggered at a very low measurement current. Single or multiple snapbacks have been observed, and it was found that the occurrence of snapback was a random event. The snapback is explained in terms of the formation of an additional percolation path due to the neutralization of negatively charged traps or the generation of neutral electron traps at certain strategic positions during the measurement.