CORRELATION OF STRESS-INDUCED LEAKAGE CURRENT IN THIN OXIDES WITH TRAP GENERATION INSIDE THE OXIDES

It has been observed that the low-level pre-tunneling leakage currents in thin oxides increased after the oxides had been subjected to high voltage stresses. These increases in the pre-tunneling currents have been correlated with the number of traps generated inside of the oxides by the high-voltage stresses. The densities of the stress-generated traps inside of the oxides were calculated using the tunneling front model and analyzing the transient currents that flowed through the oxides after removal of the stress voltage pulses. It was found that the stress-generated trap distributions were relatively uniform throughout the small portion of the oxide sampled by the transient currents. The trap densities increased as the cube root of the fluence of electrons that had passed through the oxide during the stress, independent of the stress polarity. The voltage dependence of the low-level pre-tunneling current was dependent on the sequence in which the stress voltage polarities and the low-level current measurement polarities were applied, The portion of the low-level pre-tunneling current that was not dependent on the polarity sequence was best fitted by a voltage dependence consistent with Schottky emission.