Influence of a high‐temperature hydrogen anneal on the memory characteristics ofp‐channel MNOS transistors

摘要

The effects of a postnitridation high‐temperature hydrogen anneal onp‐channel metal‐nitride‐oxide‐semiconductor (MNOS) memory transistors have been studied. It is shown that, although the density of surface states at the Si‐SiO2interface decreases with increasing temperatures, anneal temperatures exceeding the nitride deposition temperature should not be used, since they result in a nitride degradation. Short anneals at 800 °C result in a 30 reduction in the threshold voltage decay rates by elimination of backtunneling of stored charges towards the interface states. At the same time the hydrogen anneal technique guarantees a more reliable operation of transistors in the memory array and strongly increases the channel mobilities. In hydrogen‐annealed MNOS transistors the degradation process is retarded resulting in better endurance figures.