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

Abstract

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 similar to 0.3 independent of the P/E cycle and the temperature in the case of programmed cell, and 0.36 similar to 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 (N-IT) 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 similar to 0.9 in the programmed cell and n=0.65 similar to 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.