A predictive model of electron and hole decay in silicon-nitride-oxide-silicon nonvolatile memory transistors experiencing arbitrary thermal environments

A model is presented which accurately predicts the threshold voltage decay of both the excess electron and excess hole logic states of silicon-nitride-oxide-silicon nonvolatile memory transistors in thermally varying environments. The model predictions require as inputs the initial occupied trap distributions for both trapped holes and trapped electrons. A technique is presented to determine all model parameters, including the initial occupied trap distributions, by performing a single practical experiment with a specific thermal scenario. Once the model parameters are determined by this single experiment, the threshold voltage is predicted (with no adjustable parameters) for arbitrary time dependent thermal environments. Retention experiments are performed for a wide range of thermal environments which are changed during the charge decay process. The accuracy of the model predictions is verified by experimental data.