Understanding the impact of slow electro-forming in Resistive Random Access Memories

We report an experimental study to understand the reduction in the forming voltage with slow electro-forming of HfO₂ based ReRAM devices. Using a combination of capacitance-voltage and current-voltage measurements, we captured the change in capacitance due to dielectric polarization as function of voltage sweep rates. The dielectric polarization was attributed to the charge trapping or internal redistribution of charged centers under electric field. Retention testing showed that this change in capacitance was volatile and decayed to initial values over time after the removal of bias indicating a dielectric relaxation. The dielectric polarization was significantly higher when voltage-sweep rate was slow which causes electro-forming of the dielectric at lower forming voltages.