Investigation of resistance fluctuations in ReRAM: physical origin, temporal dependence and impact on memory reliability

We investigate the impact of ReRAM resistance fluctuations in a 16kb memory array. ReRAM retention and read current fluctuations are the main factors limiting the reliability of the array. A KMC-based 3D simulation framework is introduced for a complete physical description of the observed mechanisms. After individual cell relaxation (up to one second at room temperature) and resistance distribution stabilization, single cell level fluctuations still occur, especially in HRS. Oxygen vacancy migration and recombination, RTN and 1/f noise components contribute to the dynamic evolution. In a first phase, higher and faster current fluctuations are measured due to RTN and Vo low energy migration (1-10min at 25°C). In a second phase, the contribution of Vo migration tends to decrease as they neutralize in clusters or diffuse (> 10min at 25°C). Finally, the impact of individual cell fluctuations on the variability and reliability of memory array is analyzed.