Phase transition in sputtered HfO2 thin films: A qualitative Raman study

In this work the results of Linear Raman Spectroscopy experiments on hafnium dioxide (HfO2) thin films deposited by magnetron sputtering using different deposition conditions and post-deposition annealing are reported. Raman bands were identified considering the active symmetry modes expected from a tetragonal or monoclinic phase. The as-deposited HfOx films sputtered from an Hf target exhibit a tetragonal phase, which may be due to a crystallite size effect. However, the as-deposited HfOx films from the HfO2 target is found to be amorphous. As these films are annealed, these films remain or begin to become amorphous. However, at 600 °C they both begin to crystallize into a stable monoclinic phase.