Resistance and Threshold Switching Voltage Drift Behavior in Phase-Change Memory and Their Temperature Dependence at Microsecond Time Scales Studied Using a Micro-Thermal Stage

We study the drift behavior of RESET resistance R_RESET and threshold switching voltage V_th in phase-change memory (PCM) and their temperature dependence. To extend the temperature-dependent measurement to microsecond time scales, we integrate an innovative micro-thermal stage (MTS) on the PCM cell. The MTS changes the temperature of the programmed region of the PCM cell within a few microseconds by placing the Pt heater in close proximity of the programmed region. First, we experimentally verify the existing phenomenological R_RESET and V_th drift model for constant annealing temperature at various temperatures between 25°C and 185°C down to 100 μs and show that the measured temperature dependence of the drift coefficient agrees well with what is expected from the existing drift models. Based on the existing drift model for a constant annealing temperature, we derive the analytical expression for the R_RESET drift for time-varying annealing temperature and experimentally verify the analytical expression. The derived analytical expression is important to understand the impact of thermal disturbance on PCM reliability such as variations in R_RESET and V_th.