Reliability improvement of Ge2Sb2Te5-based phase-change memory devices with increased post annealing time

Abstract

The reliability of phase-change random access memory (PCRAM) can be degraded due to the diffusion of constituent atoms in the phase-change material during repetitive phase-change operations. This research reports the reliability enhancement of Ge₂Sb₂Te₅ (GST225)-based PCM device with prolonged post annealing time. The results indicate that although the on-current slightly decreases with increasing post annealing time, the voltage required to transform to the SET state remains approximately 1 V. Additionally, the endurance cycle count increases by a factor of 10 for each duration. Furthermore, compared to the device without post annealing, the RESET drift coefficient decreases by 5.3 %, 8.8 %, and 11.4 % for post annealing durations of 3 h, 9 h, and 18 h, respectively, while the SET drift coefficient decreases by 38.9 %, 51.1 %, and 59.6 %, respectively. The changes in electrical properties with increasing annealing time can be explained by analyzing the characteristics of the phase-change material, which provides insights into the impact of subsequent thermal treatment on the crystallization behavior of PCM. These findings are expected to serve as an additional approach to enhance the reliability of phase-change memory, a next-generation memory device, and to influence the understanding of the behavior of constituent elements in the development of new types of semiconductor devices based on chalcogenide materials used in phase-change memory.