A novel programming method for multilevel RRAM based on pulse width modulation

A novel programming method for multilevel resistive random access memory (RRAM) is proposed and experimentally demonstrated to improve the stability of multilevel high resistance states (HRS). By substituting a relatively long reset pulse with a series of short pulses, this method effectively reduces the resistance variation resulted from Joule heating. The standard deviation of one HRS is greatly reduced. Though this method is demonstrated on our TiN/TaOX/Pt devices, further analysis indicates its possible validity in bipolar RRAM devices based on other transition metal oxides. Stable multilevel RRAM for applications in memory chips can be achieved through this method.