NUMERICAL TRANSIENT SIMULATION OF THE PROGRAMMING WINDOW DEGRADATION IN FLOTOX EEPROM CELLS

Numerical transient simulations of the programming window degradation in FLOTOX EEPROM cells are presented. Unlike analytical solutions, thi s numerical approach takes into account the actual waveform of the pro gramming voltage. The programming window degradation can therefore be evaluated for realistic situations provided the degradation rate of th e tunnel oxide is known. The simulation enables the endurance characte ristics of the memory cells to be predicted for given programming cond itions and tunnel oxide quality. Thereby, the optimization of the cell geometry with respect to the endurance performance as well as the sel ection of the optimum programming conditions which minimize the window degradation become possible, even prior to the fabrication of the mem ory cells.