Dual-electron-injector-structure electrically alterable read-only-memory modeling studies

The threshold voltage shift of various dual-electron-injector structures (DEIS´s) which are composed of chemically vapor-deposited (CVD) stacks of Si-rich SiO2, SiO2, and Si-rich SiO2incorporated into floating polycrystalline-silicon-gate electrically alterable read-only memories (EAROM´s) has been studied as a function of write/erase voltages, write/erase times, and the initial charge state of the floating poly-Si gate and compared, to a simple physical model for a variety of different device structures. This model depends on the interface limited (Si-rich-SiO2-SiO2interfaces) enhanced current injection observed for the dual-electron-injector stacks at moderate gate voltages for both voltage polarities, the changing electric fields in the SiO2layers as the floating polycrystalline silicon gate electrode is charged or discharged, and the voltage-dependent capacitance of the dual-electron-injector stack. Good agreement is observed between the experimental data and this model. This model will be the starting point in designing more complicated device arrays for nonvolatile memory applications.