Spatial and Temporal Characterization of Programming Charge in SONOS Memory Cell: Effects of Localized Electron Trapping

Abstract

Unique features of the threshold voltage shift, DeltaV(TH) and the Source Current, I-S in SONOS cells are quantified, Utilizing the concept of trapped and localized electron charge, Q(T). Dependence of DeltaV(TH) on forward and reverse readings, and on drain or source voltages are systematically analyzed for a given programming condition. Also constant transient I-S during the programming, is elucidated. The analysis is based upon embedding localized Q(T) in, and solving the coupled Poisson and continuity equations. As a consequence, Q(T) profiles diffusing progressively in time into the channel from its drain end is quantified. The technique for extracting the trap density and Studying the cell reliability has been developed.