Understanding of the intrinsic characteristics and memory trade-offs of sub-μA filamentary RRAM operation

We optimize and investigate extensively the sub-μA bipolar operation of scaled Al₂O₃- and HfO₂-based RRAM cells using carefully thinned dielectrics and Hf scavenging layer. Although isotropic scaling favors the sub-μA operation, switching variability remains intrinsically large due to low number of involved O-vacancy switching species. The low filament temperature also accounts for slow forming/set speed. However, combining both Al₂O₃ and HfO₂ dielectrics leads to best trade-off between switching control, memory window, speed and retention.