Studies of the reverse read method and second-bit effect of 2-bit/cell nitride-trapping device by quasi-two-dimensional model

The reverse read method and second-bit effect of the 2-bit/cell nitride-trapping device are comprehensively studied by a quasi-two-dimensional (2-D) model. Based on this model, analytical equations are derived to simulate the surface potential of the device with locally injected electrons. This model indicates that the reverse read method exploits the local drain-induced barrier lowering (DIBL) effect that reduces the potential barrier produced by the locally injected electrons. The experimental results of the two-region behavior of second-bit effect can be well explained and simulated by this analytical model. Two-dimensional numerical calculations are also carried out to verify these analytical equations. The impact of short-channel effect on the second-bit effect is also examined.