On the drift behaviors of a phase change memory (PCM) cell

This paper presents a HSPICE macromodel of a phase change memory (PCM) by considering the phenomenon of drift behavior as leading to incorrect operation. The model simulates the behavior due to the drift in the resistance and threshold voltage when the cell is not been read or programmed. It considers not only the resistance change by phase (as corresponding to the two phases, amorphous and crystalline), but also the temperature, the crystalline fraction and the continuous profile of the resistance. This electrical based modeling by HSPICE allows to fully characterizing the holding voltage and the continuous behavior of the PCM resistance, while assessing the impact of the programming time of the drifted parameters. The proposed macromodel generates the I-V and R-I plots of a PCM cell at a very small error compared with experimental data. A detailed sensitivity analysis of the electrical parameters of the PCM cell is pursued to show the robust characteristics of the proposed macromodel to capture the variation in parameters due to drift.