Structural characterization of Mo/Ru/Si EUV reflector by optical modeling

The performance of multilayer extreme ultraviolet (EUV) reflector has direct bearing on the process throughput and cost of new technology. Using measured data from the experimentally manufactured reflector, we intended, in this work, to show that the reflectivity of the Bragg reflector can be characterized by structural parameters such as d-spacing, density, and the thickness of inter-diffusion layers and oxidation layer. This quantitative analysis of the reflectivity derived from the structural parameters can be utilized to optimize the optical properties of the existing Mo/Ru/Si system as well as to provide fundamental insights into the science involved in a Bragg EUV reflector.