Effect of RF power of post-deposition oxygen treatment on HfO2 gate dielectrics

The radio frequency (RF) power effect of post-deposition O2 plasma treatment on the physical, electrical, and reliability characteristics of high-k HfO2 dielectric films was comprehensively investigated in this study. The experimental results indicated that increasing the RF power of post-deposition O2 plasma treatment resulted in a stoichiometric HfO2 film, but led to a thinner interfacial layer and the formation of new HfSi bonds. Additionally, the electrical performance and reliability of HfO2 dielectric films were significantly impacted by the RF power of the post-deposition O2 plasma treatment. As the RF power is less than 30 W, the leakage current density and time-to-breakdown of the O2 plasma-treated HfO2 films were improved in comparison with those of the as-deposited samples. However, further increasing RF power to exceed 50 W would cause the continuous degradation in the electrical performance and reliability due to the plasma damage induced by oxygen active spices in a plasma environment. Therefore, performing a post-deposition O2 plasma treatment process on the as-deposited HfO2 dielectric films can effectively improve the dielectric's properties. However, the applied RF power is an essential controlling parameter, avoiding serious plasma damage occurrence.