THE SEARCH FOR CATHODE AND ANODE TRAPS IN HIGH-VOLTAGE STRESSED SILICON-OXIDES

When silicon oxide is stressed at high voltages, traps are generated i nside the oxide and at the oxide's interfaces. The traps are negativel y charged near the cathode and positively charged near the anode. The charge state of the traps can be easily changed by application of low voltages. Several models of trap generation have been proposed. These models involve either electron impact ionization processes or high fie ld generation processes. We have attempted to determine the relative t rap locations inside the oxides for oxides between 5 and 80 nm thick, in order determine which processes are most likely. No evidence for a higher density of traps near the anode in any of these oxides was foun d, casting doubt on the efficiency of the impact ionization process in trap generation, even in thicker oxides. These data would support a t rap generation model controlled by the high fields inside the oxides.