Effect of High-Pressure Oxygen Annealing on Electrical Characteristics of Metal-Alumina-Nitride-Oxide-Silicon-Type Flash Memory Devices

摘要

We have investigated the effect of high-pressure oxygen annealing (HPOA) on metal-alumina-nitride-oxide-silicon (MANOS)-type flash memory devices. HPOA devices show significant improvement of retention characteristics at elevated temperatures under positive gate bias owing to the reduction of charge loss rate through the blocking oxide. Considering the improvement of electrical characteristics and the change in the Al chemical state, this was attributed to the effective removal of traps and the recovery of the stoichiometry of Al_2O_3 layer by oxygen passivation. We also confirmed this effect in a Si-Al_2O_3-Pt capacitor. As a result, we consider that HPOA could be a crucial process for future MANOS-type memory devices.