Phase-Change Memory: Performance, Roles and Challenges

In this paper we analyze recent progress in Phase- Change Memory (PCM) technology targeting both Storage Class Memory and embedded applications. The challenge to achieve a high temperature data retention without compromising the device programming speed can be addressed by material engineering. We show that volume and thermal confinement improvement of the phase-change material enables a high (10-fold) reduction of the programming current, achieved also by the optimization of the device architecture, in particular in the case of a confined structure. It leads to a higher cell efficiency proven by a 6× reduction of the programming current density wrt a standard PCM structure. Furthermore, we demonstrate the reduction of thermal losses by the tuning of the thermal conductivity of the dielectrics surrounding the phase-change material. Finally, we propose some considerations about the PCM ultimate scaling and the reliability at such dimensions, showing that the engineering of the bottom electrode/phase-change material interface can lead to a reduced variability in scaled devices.