Characterization of reset state through energy activation study in Ge-GST based ePCM

Embedded phase change memories (ePCM) based on Ge-rich Ge2Sb2Te5 (Ge-GST) alloys are gaining increasing interest in recent years from the scientific community. The introduction of Ge-GST allows to meet the retention specifications of embedded nonvolatile memory (eNVM), where stored codes and parameters must remain unaffected by the high-temperature soldering reflow. This work presents a detailed study of the reset state of the ePCM. Resistance drift and the conduction mechanisms are assessed for different bake times and temperatures. For the first time, evolution of the activation energy for conduction is detailed for the Ge-GST compound. Finally the dependence of the activation energy and resistance value on the forming state is assessed.