A Physics-Based Crystallization Model for Retention in Phase-Change Memories

A new model for data retention in phase-change memory cells is proposed. The model describes the formation of crystalline grains in the amorphous phase according to the standard nucleation theory. A conduction percolation concept is then applied to calculate the crystallization time for the cell. The model is used to account for the experimentally extracted nucleation/growth parameter and to provide a physics-based extrapolation method to predict retention lifetime at relatively low temperature. The sensitivity of the extrapolated results on different approximations for the Gibbs free energy of amorphous-to-crystalline transition and to material-related crystallization parameters is finally analyzed.