Comparative investigation of endurance and bias temperature instability characteristics in metal-Al₂O₃-nitride-oxide-semiconductor (MANOS) and semiconductor-oxide-nitride-oxide-semiconductor (SONOS) charge trap flash memory

The program/erase (P/E) cyclic endurances including bias temperature instability (BTI) behaviors of Metal-Al2O3-Nitride-Oxide-Semicon-ductor (MANOS) memories are investigated in comparison with those of Semiconductor-Oxide-Nitride-Oxide-Semiconductor (SONOS) memories. In terms of BTI behaviors, the SONOS power-law exponent n is ~0.3 independent of the P/E cycle and the temperature in the case of programmed cell, and 0.36~0.66 sensitive to the temperature in case of erased cell. Physical mechanisms are observed with thermally activated h* diffusion-induced Si/SiO₂ interface trap (NIT) curing and Poole-Frenkel emission of holes trapped in border trap in the bottom oxide (N_OT). In terms of the BTI behavior in MANOS memory cells, the power-law exponent is n=0.4~0.9 in the programmed cell and n=0.65~1.2 in the erased cell, which means that the power law is strong function of the number of P/E cycles, not of the temperature. Related mechanism is can be explained by the competition between the cycle-induced degradation of P/E efficiency and the temperature-controlled h* diffusion followed by N_IT passivation.