Size dependence of TiN/HfO2/Ti MIM ReRAM resistance states: Model and experimental results

The size dependence of the resistance states of a TiN/HfO2/Ti resistance random access memory (ReRAM) metal–insulator–metal (MIM) structure is described in terms of the filament distribution within the structure. We introduce radial distribution functions to model process-induced effects on the density of percolating conduction paths in the oxide. A suitably chosen function can accurately model the size dependence of the HIGH resistance ReRAM state. On the other hand, the size independence of the LOW state is attributed to the selection of a dominant filament. Our experimental results match the proposed explanations very well, if the distribution of HIGH state conduction paths is dominated by process effects near the edge of the ReRAM cell, while the distribution of LOW state conduction paths is very localized somewhere within the ReRAM cell.