Reliability of low current filamentary HfO2 RRAM discussed in the framework of the hourglass SET/RESET model

We review our recent work on modeling of low current filamentary switching in amorphous HfO2 RRAM. The conduction is controlled by the width of the constriction, determining the electron transmission. The set and reset processes are modeled as a dynamic flow between two oxygen vacancy reservoirs connected by a narrow constriction. Reset is described as a dynamic balance between an upward and downward vacancy flow, while the set process is modeled as an unbalanced filament growth bounded by the external compliance. In the framework of this model, we discuss the intrinsic instabilities of narrow filamentary conduction that give rise to a series of reliability issue such as disturb and endurance. We explore some possible routes for improving the reliability.