Understanding the Role of the Ti Metal Electrode on the Forming of HfO2-Based RRAMs

In this paper we investigate in details the effects of the Ti metal electrode on the forming operation in HfO₂ RRAM devices. Starting from electrical data and physico-chemical analysis, we use physics-based RRAM modeling to understand the physics governing the CF formation in RRAM stacks with Ti electrodes. Simulations show that the lower forming voltage typically observed in these devices is due to the Ti-induced formation of a sub-stoichiometric HfO_x region in the resistive switching layer. The model allows extracting the characteristics of this sub-stoichiometric region that are crucial for developing future low-voltage RRAM devices.