Ion beam sputtering of fluoride thin films for 193 nm applications

Ion beam sputtering of AlF3, LaF3, and GdF3 as single layers, AR coatings, and HR coatings for 193 nm is presented. The resulting optical properties, such as reflectance/transmittance and optical constants, and material properties, such as surface roughness and film durability, are discussed. The low temperature of the process allows for both CaF2 and fused silica substrates to be used with the same optical results.