Flash EPROM endurance simulation using physics-based models

A novel unified field-dependent oxide charge generation (FDG) model is introduced to consistently simulate oxide degradation due to Fowler Nordheim (FN) tunneling and hot carrier injection (HCI) stresses over a wide range of oxide field intensity. This model, combined with an interface charge generation model, is used to study effects of stress-induced interface and oxide charges on flash device erase and programming speeds, band-to-band tunneling leakage current, and threshold voltage shift. An efficient cycle-weighting method is introduced to simulate flash device programming/erase (P/E) cycle endurance. Excellent agreement has been achieved between the simulation predications and experimental data over various operation conditions without parameter fittings or preassumed interface and oxide charge distributions. Simulation results show that the endurance characteristics are mainly affected by both the P/E gate current reduction due to oxide charges and the flat-band voltage increase due to both oxide and interface charges.<>