Characterization of thin films and bulk materials for DUV optical components

Applications of excimer lasers in the deep ultraviolet (DUV) for optical lithography, medicine and material processing are steadily growing together with drastically increasing requirements for low-loss optics. This leads to crucial requirements for at-wavelength characterization tools. For a thorough investigation of optical losses, all mechanisms contributing to the total loss have to be taken into account, comprising scattering at surfaces, thin film interfaces, and in bulk materials. Because of the strong wavelength-dependence of scattering (~1/λ2,1/λ4), this in particular holds for DUV optical components designed for high-end applications at 193 nm. Therefore, a system for the measurement of angle resolved and total scattering at 193 nm and 157 nm was developed at the IOF in Jena. The system enables at-wavelength scattering measurement and analysis of DUV optical components. Examples of investigations are discussed such as scatter analysis of all-fluoride thin film coatings on differently polished substrates and bulk scatter properties of synthetic fused silica.