Comprehensive understanding of conductive filament characteristics and retention properties for highly reliable ReRAM

We have proposed a retention degradation model based on an oxygen diffusion and percolation path cut mechanism in a filament of TaO_x bipolar ReRAM. We have developed a new methodology for quantitating the conductive filament characteristics and have revealed that the retention property of ReRAMs can be explained in terms of filament characteristics, including filament size S, density of oxygen vacancies N(Vo), and density of residual oxygen N(O_x). We have improved the retention property of ReRAM under low current operation, by controlling these filament characteristics.