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

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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 30W, 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 50W 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.