Conductive Filament Scaling of ${\rm TaO}_{\rm x}$ Bipolar ReRAM for Improving Data Retention Under Low Operation Current

The retention model of a bipolar ReRAM considering the percolative paths in a conductive filament is proposed. We demonstrate, for the first time, that the control of oxygen vacancy concentration in a conductive filament is the key for ensuring data retention including tail bits. To improve the retention property under low-current operation, the size of the conductive filament must be scaled down while keeping the density of oxygen vacancy high enough. Based on this concept, we demonstrate both low-current operation and sufficient retention results exceeding 500 h at 150^°C, which correspond to more than 10 years at 85^°C.