Numerical Implementation of Low Field Resistance Drift for Phase Change Memory Simulations

Phase change memories (PCM) are strongly believed to be an important technology for the memory application field, aiming to be at leading edge beyond 32 nm. Among the basic physical mechanisms related to the PCM device operation, low field resistance drift is actually one of the most interesting features of chalcogenides affecting the electrical behavior of the amorphous phase and thus having important implications in the PCM multilevel memory design. In this paper we present a drift model based on the electrically active defect formation theory. The model has been integrated in a physically-based numerical solver and a quantitative agreement with the electrical data is shown. An explanation of the experimentally observed dependence of the drift coefficient on the resistance values is finally provided.