Structure Optimization of 4X NM Nor Flash for Improving Cell Performance

ETOX devices with high-tech nodes offer superior PGM/ERS efficiency, but there are challenges in maintaining PGM/ERS Vt window when developing more advanced technical node. In this paper, a feasible optimization strategy is proposed to improve attenuation of Vt Windows in shrunken ETOX NOR Flash. Based on the technological parameters of 4X nm NOR Flash, the CG filling window is adjusted by increasing the amount of etching in the nitride pullback to improve the coverage ratio of CG on FG. Therefore, the gate coupling ratio of device is optimized. In addition, it shows the same trend in traditional cell that Vt window can be enhanced by optimizing the coupling ratio. On the one hand, it provides an efficient PGM/ERS strategy for shrunken NOR Flash, on the other hand, the widened FG space increases the CG filling window. The experimental results after process optimization show that the Vt window is improved by at least 10% and obtain an extra 10% for CG filling Window in tiny cell.