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 Al
₂
O
₃
- and HfO
₂
-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 Al
₂
O
₃
and HfO
₂
dielectrics leads to best trade-off between switching control, memory window, speed and retention.