Modeling and simulation of conduction characteristics and programming operation in nanoscaled phase-change memory cells

摘要

A numerical model for electro-thermal simulations of phase-change memories is described. The model employs the Dessis platform to calculate the current-voltage characteristics, the temperature profile and the phase transformation in the cell according to the standard techniques for semiconductor devices. The basis of the model is first shown, describing the band-structure models for the crystalline and the amorphous phases and the numerical approach used. The simulation of the reset operation is then described, focusing on the procedure for the calibration of electrical and thermal parameters. In particular, the comparison between simulation and experimental results for different cell geometries and sizes is shown, allowing to obtain a full confidence of the model accuracy over an extended range of cell geometry. The crystallization process is addressed, including high-temperature set operation (100 ns time range) and low-temperature crystallization for accelerated bake analysis of data retention. Finally, the several applications of the model are shown, highlighting the optimization procedure of the cell and the scaling investigation of phase-change cells.