Ultralow sub-500nA operating current high-performance TiN\Al2O3\HfO2\Hf\TiN bipolar RRAM achieved through understanding-based stack-engineering

We demonstrate sub-500nA switching and tunable set voltage by inserting thin Al
₂
O
₃
layer in TiN\HfO
₂
\Hf\TiN RRAM cell. Stack engineering clearly led to novel insights into the switching phenomenology: (i) O-scavenging is key in the forming process and stack-asymmetry management; (ii) dielectric-stack thinning allows lower forming current; (iii) `natural' (asymmetry-induced) reset switching takes place close to the TiN anode; (iv) reset resistance is limited by material-barrier properties at TiN interface.