Microstructure related properties of lanthanum fluoride films deposited by molybdenum boat evaporation at 193 nm

Single layer lanthanum fluoride (LaF3) at 193 nm was deposited by a molybdenum boat evaporation process. Various microstructures that formed under different substrate temperatures and with deposition rates were investigated. The relation between these microstructures (including cross section morphology, surface roughness and crystalline structure), the optical properties (including refractive index and optical loss) and mechanical properties (stress) were investigated. It was found that the laser-induced damage threshold (LIDT) was affected by the microstructure and composition of the thin film. To obtain a larger LIDT value and better optical characteristics, LaF3 films should be deposited at a high substrate temperature and a low deposition rate.