Operation Dynamics in Phase-Change Memory Cells and the Role of Access Devices

A detailed physical model of the heating and amorphization profiles in phase-change memory elements is applied to illustrate the effects of loads and pulse rise times on the reset operation of phase-change memory cells. Finite element modeling of the electrical and thermal transport is used for a mushroom phase-change memory element -- including temperature dependent materials parameters, thermoelectric terms and thermal boundary resistance between different materials - and integrated idealized circuit models are used for the access devices (MOSFET and diode, with a separate series resistance). The results show certain windows of loads and transient times that lead to successful reset operation without excessive wasted power, for the particular PCM cells and programming conditions simulated.