Distribution and impact of local trapped charges in silicon-oxide-nitride-oxide-silicon (SONOS) memory

In this paper we propose a two-transistor model with an R(PT) for the punch-through resistor in the silicon-oxide-nitride-oxide-silicon (SONOS) memory cell. With this model, the subthreshold leakage current induced by the local trapped charges in silicon nitride and the impact on the cell's read characteristics are studied. Some solutions to decrease this leakage current and change the distribution of the trapped charges are proposed and analyzed, including programming condition optimization, the channel initiated secondary electron (CHISEL) programming, and cell structure optimization. Moreover, using the CHISEL or channel hot electron (CHE) programming, the influences on the programming and the erase characteristics of different charge distributions are investigated.