Development of soft x-ray laser irradiation beamline for damage examination of soft x-ray/EUV optics

The soft x-ray laser (SXRL) is one of attractive x-ray source for ablation study, because the ablation threshold obtained with the focused SXRL pulse having the wavelength of 13.9 nm and duration of 7 ps is much smaller than those obtained with other lasers having longer durations and/or longer wavelengths. The low ablation threshold of a material for the SXRL beam has a possibility of efficient nanometer scale surface direct machining by an ablation. In addition, the wavelength of the SXRL is very close to the wavelength of the extreme ultraviolet lithography system (λ = 13.5 nm). So, the SXRL has an ability not only to confirm the ablation threshold but also to examine the damage property of the extreme ultraviolet (EUV) optical elements, which have the same specifications of those in the EUV lithography. To examine the damage threshold and/or durability of EUV optical elements, we develop the soft x-ray laser irradiation system. The irradiation system has an intensity monitor based on the Mo/Si multilayer beam splitter. This intensity monitor provides the irradiation energy onto sample surface.The 11th International Conference on Inertial Fusion Sciences and Applications (IFSA 2019