Statistical and scaling behavior of structural relaxation effects in phase-change memory (PCM) devices

The phase-change memory (PCM) technology represents one of the most attractive concepts for next generation data storage. PCM behavior is mainly limited by the structural relaxation (SR) and by the crystallization of an amorphous chalcogenide material: the ternary alloy Ge₂Sb₂Te₅. SR is a local structural-rearrangement at the atomic/bonding scale and crystallization is the reaching of a periodic atomic structure. While the retention capabilities related to crystallization have been already extensively addressed in the literature, both at the single-cell and at the statistical level, those related to SR have been mainly studied at the intrinsic level and a statistical analysis at the device level is still lacking. The purpose of this paper is to study the statistical and scaling behavior of the SR phenomenon in PCM devices, through experimental and modeling tools, allowing for long term, physics-based, reliability extrapolations in large-scaled PCM arrays.