First principle study of the stability of H atoms in SiN layers on MONOS-type memories during program/erase operations

Recently, hydrogen has been recognized as an important heteroatom in Metal-Oxide-Nitride-Oxide-Semiconductor (MONOS) -type memories for its quality improvement. However, if stability of H atoms in SiN layers changes by applying high voltage, memory characteristics of MONOS-type memories change during program/erase (P/E) operations, resulting in memory degradation. Therefore, in this paper, we have investigated the stability of H atoms in SiN charge trapping layers of MONOS-type memories during P/E operations by using first principles calculations. Our calculations show that H atoms in Si or N vacancies in SiN layers become unstable and migrate when high voltage is applied, leading to memory degradation with changes of memory characteristics. This result clearly indicates that suppression of H atoms in SiN layers is necessary for realization of high quality MONOS-type memories.