Thermal disturbance and its impact on reliability of phase-change memory studied by the micro-thermal stage

In this paper, we study thermal disturbance and its impact on reliability using a novel measurement structure - the micro-thermal stage (MTS). The small thermal time constant of the MTS extends the time-scale of temperature dependence measurement to ~100 μs. The reliability of phase-change memory (PCM) is evaluated in terms of data retention and variation of the high resistance (RESET) state resistance (R_RESET) and the threshold switching voltage (V_th). We experimentally show how the impact of thermal disturbances on retention is accumulated and its dependence on the electric field. The thermal disturbance effect on RR_RESET variation changes with time and it is the largest for the shortest time delay after RESET programming. Thermal disturbance can cause at least 25 and 100% variation for RR_RESET and V_th respectively in the given thermal disturbance scenario. We propose an effective method to exploit thermal disturbance to make multi-bit operation more robust.