A Combined Modulation of Set Current With Reset Voltage to Achieve 2-bit/cell Performance for Filament-Based RRAM

A combined operation scheme to realize multibit switching in filament-based bipolar RRAM device is proposed. By combining the modulations of the current compliance in set operations with the stop voltage in reset operations together, the size or the quantity of the filaments in the film bulk can be controlled. An RRAM device with the structure of Ag/HfOx/Pt is fabricated and the 2-bit/cell memory function is achieved by the proposed modulation. Furthermore, the 2-bit/cell data reliability is satisfactory including the high-temperature retention, cycling endurance.