New physical model to explain logarithmic time dependence of data retention in flash EEPROM

Data retention after program/erase (P/E) cycles is one of the most important reliability issues in a flash EEPROM. Electron detrapping is the main cause of data leakage in the state-of-the-art flash EEPROM. The log(t) dependence of ΔVth is a unique aspect of the electron detrapping. To explain log(t) dependence, we have assumed that after electron detrapping, the positive-ionized trap reduces the probability of electrons in the influence area being emitted from their site. Based on this assumption, we have proposed a model of detrapping which is consistent with the experimental results.