Assessment of distributed-cycling schemes on 45nm NOR flash memory arrays

This paper investigates the validity of distributed-cycling schemes on scaled Flash memory technologies. These schemes rely on the possibility to emulate on-field device operation by increasing the cycling temperature according to an Arrhenius law, but the assessment of the activation energy that has to be used on scaled technologies requires a careful control of the experimental tests, preventing spurious second-order effects to emerge. In particular, long gate-stresses required to gather the array threshold voltage (V_T) map are shown to give rise to parasitic V_T-drifts, which add to the V_T-loss coming from damage recovery during post-cycling bake. When the superposition of the two phenomena is taken into account, the effectiveness of the conventional qualification schemes relying on a 1.1 eV activation energy is fully confirmed at the 45 nm NOR node.