Statistical modeling of bit distributions in Phase Change Memories

The capability to handle multi-level cells is an appealing challenge to reach a high degree of integration also in the field of phase change memories (PCMs). To this aim, tight current (or bit) distributions are needed so as to allocate all programmed levels in the allowed window. As opposed to the above requirement, technology driven spreads tend to increase when the memory cell shrinks to nanoscale sizes, and even atomic scale fluctuations can play an important role. In this scenario, the present work provides a new physically based approach that allows describing the statistical spread for the bit distributions of PCM arrays through a viable and flexible SPICE-like model.