Debris-free Euv Source for At-wavelength Metrology

Parallel to the development and optimization of high-power EUV sources for lithography, the realization of low-cost EUV sources for at-wavelength metrology is strongly required. These sources are important tools for the characterization of EUV mirrors and masks, for the determination of thin film transmission (EUV filters), for research on resist materials, and for the calibration of EUV detectors. Apart from the very expensive synchrotron facilities, EUV sources for metrology are presently based on laseror discharge-produced plasmas. Besides a complex setup and high running costs, these sources operate at a relatively low repetition rate, exhibit considerable temporal and spatial fluctuations, and always require techniques for debris mitigation.