Resistance drift in phase change memory

This paper discusses the major reliability issue in MLC PCM, namely time dependent resistance drift in amorphous chalcogenide materials. Starting from experimental observations, this paper presents a complete physical picture for structural relaxation (SR), which is considered to be the underlying mechanism for resistance drift. In particularly, various physics models and quantum molecular dynamics simulation are presented to reveal the interrelationship between atomic structure and electrical properties of amorphous chalcogenide materials. The paper provides insights to develop mitigation techniques including material engineering and various design techniques, etc. to ensure reliable MLC operations.