Aluminum oxyfluoride films for deep ultraviolet optics deposited by a combined HIPIMS/CFUBMS deposition technique

Aluminum oxyfluoride films were deposited by a combined HIPIMS/CFUBMS deposition technique with Al targets at room temperature. In order to obtain better optical and mechanical properties, films were investigated under different duty cycles and CF4 gas flow rates. The optical properties in deep ultraviolet range, microstructure, surface roughness, and crystalline structure of aluminum oxyfluoride films have been studied. The aluminum oxyfluoride films deposited with 45/255 duty cycle and 0.8 sccm CF4 had the lowest extinction coefficient (8 × 10−4) and the highest refractive index (1.72) at 193 nm. Additionally, aluminum oxyfluoride films revealed a dense and amorphous structure with 0.155 nm surface roughness.