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 HfO_x film using the Hf target exhibits a tetragonal phase, what is likely due to a crystallite size effect. However, as-deposited HfO_x film using the HfO₂ target is amorphous. As the annealing temperature increases both films begin to become amorphous. At 600°C they start to crystallize into a stable monoclinic phase.