ePCM reliability improvement through active material carbon implantation

Embedded Phase Change Memories (ePCM) based on Ge-rich Ge2Sb2Te5 alloy have been proven to guarantee code integrity after soldering thermal profile and data retention in extended temperature range for automotive application. A characteristic of this kind of alloy is Ge segregation during the fabrication process. This paper shows how carbon implantation can influence this phenomenon on a process not optimized to contain Ge segregation leading to a more homogeneous and stable alloy. This effect was demonstrated by detailed physical and chemical analysis and the impact on electrical performances was investigated at intrinsic cell level and on a 20Mbit array.