Guiding principles for charge trap memories -A theoretical approach-

We have proposed atomistic guiding principles for high program/erase (P/E) cycle endurance MONOS type memories based on first principles calculations. We found that excess O atoms near the SiN/SiO₂ interfaces are the cause of memory degradation due to an irreversible structural change during P/E cycles. These results indicate that by suppressing excess O atoms the MONOS characteristics can be effectively improved. Based on the calculated results, we proposed that a defect with Jahn-Teller type structural changes is one of the most suitable traps for charge trap memories, since Jahn-Teller distortion is essentially reversible during P/E cycles with very little degradation. Moreover, we also investigate the H incorporation effects.