Dielectrics and Metal Stack Engineering for Multilevel Resistive Random-Access Memory

Abstract

In this work, we have fabricated and evaluated a HfO2/Al2O3 bilayer structure for a two-terminal ReRAM device to have multiple resistance states as a function of compliance current (CC). Reduced power consumption was observed when the Al2O3 buffer layer was placed between the top electrode and the HfO2 layer as compared to when it is embedded between the HfO2 layer and the bottom electrode. Gradual resistance change capability was observed with varying CC. It was demonstrated that the presence of oxygen vacancies closer to the top electrode reduces the switching energy. Decreasing the thickness of the Al2O3 buffer layer, near the bottom electrode, increases the switching power requirement. It was also observed that the switching energy requirement could be altered by modifying the deposition process of the top metal layer.