Oxygen Recovery in Hf Oxide Films Fabricated by Sputtering

The chemical structure of ultrathin Hf oxide films (< 10nm) fabricated by a standard sputtering method is investigated using x-ray spectroscopy and Rutherford backscattering spectroscopy. According to the experiments, oxygen species are impacted to the HfO₂/Si interface during the initial sputtering, and then released back to the upper HfO₂ region driven by the oxygen concentration grads. A vacuum annealing can greatly enhance this recovery process. Additionally, significant SiO₂ reduction in the interface is observed after the vacuum annealing for the thick HfO₂ films in our experiment. It might be an effective method to confine the interfacial layer thickness by sputtering thick HfO₂ in no-oxygen ambient.