In this study, we propose a simple and indirect method to determine the optical constants of Mo and ITO thin films in the extreme ultraviolet (EUV) wavelength region by using X-ray reflectometry (XRR) and Rutherford backscattering spectrometry (RBS). Mo and ITO films were deposited on silicon substrates by using an RF magnetron sputtering method. The density and the composition of the deposited films were evaluated from the XRR and RBS analysis, respectively and then the optical constants of the Mo and ITO films were determined by an indirect optical method. The results suggest that the indirect method by using the XRR and RBS analysis will be useful to search for suitable high absorbing EUVL mask material quickly.
In this study, we propose binary mask (BIM) designs with single- and double-layer absorber stacks with high optical contrast at a wavelength of 13.5 nm for use in extreme ultraviolet lithography (EUVL) and actinic defect inspection. The optimum thickness of the absorber stack was estimated using a method based on the transfer matrix. In the double-layer designs, [Ag/SnTe] has a minimum thickness of ∼32 nm with almost 100% optical contrast compared to the TaN layer. In addition, a SnTe absorber layer was deposited using radio frequency magnetron sputtering. The optical constant of the SnTe layer at 13.5 nm wavelength was determined using the density of the layer, which was obtained from x-ray reflectivity measurements. The reflectance of the SnTe single-layer absorber stack was measured in the EUV region and compared with the simulated reflectance by using the calculated optical constants. The results show that the new BIM designs for EUVL and actinic inspection can be helpful in reducing the geometric shadow effect compared to the TaN absorber layer with a thickness of ∼70 nm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.