Random telegraph signal noise in phase change memory devices

Reliability in phase-change memory (PCM) devices is mainly related to the metastable nature of the amorphous phase, affected by crystallization and structural relaxation (SR) processes. More recently, low-frequency noise has attracted interest both as a valuable investigation tool of the microscopic properties of the chalcogenide material and as a possible reliability topic for future technology nodes. Moreover the recent appearance of random telegraph-signal noise (RTN) as a result of cell downscaling supports the need of a deeper insight into these phenomena. This work presents for the first time RTN in PCM, describing both frequency and time dependences of the noise. We analyze (i) the R dependence with the aid of a distributed Poole-Frenkel (DPF) conduction model and (ii) the voltage and temperature dependences, discussing possible physical origins of RTN in phase-change memories.