Effects of Oxygen Partial Pressure on the Sputtered Hafnium Oxide Thin Films for Resistive Random-Access Memory

Hafnium oxide thin films were deposited on silicon substrates by RF reactive magnetron sputtering. The effects of oxygen partial pressure, tuned by the O2/Ar flow ratio, on the microstructure and electrical properties were characterized. All HfOx thin films exhibit monoclinic phases. As the increase of O2/Ar flow ratio from 0.08 to 0.33, the crystallinity is improved accompanied with the decreases of flat band voltage and leakage current density. However, when the O2/Ar flow ratio further increases to 0.5, the crystallinity becomes worse with the increase of flat band voltage and leakage current. The HfOx based resistive random-access memory (RRAM) has been fabricated and its storage properties were also investigated.