Effects of a high-temperature hydrogen anneal on the memory retention of metal-nitride-oxide-silicon transistors at elevated temperatures

Abstract

The effects of a postnitridation high-temperature hydrogen anneal on the discharge behavior at elevated temperatures during continuous reading of the written state of p-channel metal-nitride-oxide-silicon memory transistors is studied. It is shown that by the annealing the threshold voltage decay of transistors being written and read at 125 °C can be reduced by more than 20%. This makes the information retention capability of annealed devices operating at 125 °C to be better than that of unannealed devices operated at room temperature. By using different read voltage polarities it is shown that the improved retention in annealed devices can be ascribed to the elimination of the backtunneling of holes to the Si-SiO2 interface states.