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.