Spectroscopic and energetic characterization of capillary discharge plasmas devoted to EUV production for new lithography generation

Summary form only given. We report on the investigation of three types of capillary discharges likely to produce significant amount of EUV photons for the new lithography generation The discharges are driven by low inductance capacitor banks connected in Blumlein configuration and switched by high repetition rate commutation devices. Currents of a few kA are produced for driving capillaries of selected material or filled with appropriate gas or excited between different electrode shapes and material. The main goal of our investigations was to optimize the EUV power in the 10 to 14 nm spectral range. The influence of the charging voltage, current rise time, capillary parameters (gas, material, length, diameter, pressure) on the EUV production has been analyzed by electrical measurements and time resolved EUV spectroscopic experiments. The energy radiated in the different capillaries was measured with the use of XUV silicon photodiodes and selected spectral filters. A first conclusion was that the energy injected in the capillary had to be matched to an optimal value depending on the capillary parameters and on the gas.