An analytical model for optimization of programming efficiency and uniformity of split gate source-side injection SuperFlash memory

An analytical model for evaluating the programming efficiency and uniformity of SST SuperFlash cells is developed for the first time. Starting with a two-dimensional electric field analysis, this model calculates the effective hot electron injection-induced gate current during programming. Based on a full transient simulation of the calculated gate current, the time to program is then developed and used as a figure of merit to evaluate SST cells programming. The time-to-program model predicts the nonlinear transformation from control-floating gate coupling ratios to the programming speed and the programming distribution broadening correlates with coupling ratios. The model also suggests that higher bias voltage of (V_d-V_cg) and a lower coupling ratio should result in better programming efficiency and uniformity.