THE SUPERPOSITION OF TRANSIENT LOW-LEVEL LEAKAGE CURRENTS IN STRESSED SILICON-OXIDES

Thin films of silicon oxide were stressed at high voltages, which generated traps inside of the oxides and at the oxide interfaces. The transient low-level leakage currents were measured in these stressed oxides as a function of the magnitude of low voltages applied after the stress. It was found that the transient low-level leakage currents resulting from the application of two voltage pulses of different magnitudes with no relaxation time between the pulses were the same as the linear superposition of the currents resulting from each pulse when measured separately. The linear superposition of these transient currents can result in currents which change polarity during the application of a constant voltage across the oxide. This bipolar current is due to the transient charging and discharging of stress generated traps, which are distributed in space and energy within the oxide.