Durable fluoride nanocomposite coatings for photolithography

One of the reasons why the current optics used in 193 nm lithography do not have sufficiently high reflectivity and have poor optical timing is the lack of a low-refractive-index material with low absorption, low scattering, low residual stress, amorphous structure, and good aging resistance. In this study, we investigated the effect of the AlF3 content in MgF2-based low-refractive-index materials on the microstructure and optical properties of Mg1-xAlxF nanocomposite coatings prepared by thermal evaporation. Based on these findings, this study successfully solved the problems of large absorption, easy crystallization tendency, and poor aging performance of thermally evaporated AlF3 films. A novel low-refractive-index nanocomposite material with improved absorption reduction, scattering suppression, and aging resistance was obtained, which can be applied to the study of reflective optics for 193 nm lithography.