Beamline for measurement and characterization of multilayer optics for EUV lithography

Currently, intense efforts are in progress to develop a system to print 0.1 mu m features operating at an extreme ultraviolet (EW) wavelength between 11 and 14 nm, Such a development is critically dependent on the multilayer reflectors which are needed to coat the reflective masks and the optical elements of both the condenser and the projection systems. Understanding of the optical properties of these coatings (period, reflectivity, scattering, etc.) requires an accurate, well-characterized and stable measurement facility operating over the appropriate wavelength range. This paper describes a beamline installed on a synchrotron radiation source (the Advanced Light Source) which provides exceptionally high flux, high spectral resolution, absolute wavelength calibration, and excellent higher order suppression in the EW range. It allows reflectivity measurements to be made to a precision of better than 0.5%, determination of wavelength to 0.01%, and the measurement of scattering down to 10(-10) of the specular beam. The achievement of this performance through, the design of the beamline is briefly discussed, and a variety of representative results are presented.