Development of a robust 2T-SONOS cell for embedded flash application

In this paper, optimization and physical scaling of the SONOS ONO triple layer are extensively evaluated, with detailed characterization of the Flash cell behavior. Reliability tests have demonstrated high temperature endurance and long-term data retention. The results have shown that the reliability requirement is attainable even with down scaling of the vertical component of the oxynitride charge trapping layer, which makes it feasible to operate the cell at a lower programming voltage. Low leakage performance at high temperature(175°C) and a significant shrinkage in lateral geometry of a 2T-SONOS cell are demonstrated in a 0.13μm technology platform. Extensive characterization of data retention and endurance with respect to the threshold voltage and cell current degradation as well as cell disturbance in a flash array has been performed. The results have shown that a highly promising 2T-SONOS cell for application in embedded Flash, based on the modified Fowler-Nordheim tunnelling concept, is demonstrated.