Beamline for metrology of x-ray/EUV optics at the advanced light source

We describe a bending magnet beamline for the characterization of optical elements (mirrors, gratings, multilayers, detectors, etc.) in the energy range 50-1000 eV. Although it was designed primarily for precision reflectometry of multilayer reflecting optics for EUV projection lithography, it has capabilities for a wide range of measurements. The optics consist of a monachromator, a reflectometer, a 3-mirror order suppressor, and focusing mirrors to provide a small spot on the sample. The monochromator is a very compact entrance slitless, varied line spacing plane grating design in which the mechanically ruled grating operates in the converging light from a spherical mirror working at high demagnification. Aberrations of the mirror are corrected by the line spacing variation, so that the spectral resolving power lambda/Delta lambda is limited by the ALS source size to about 7000. Wavelength is scanned by simple rotation of the grating with a fixed exit slit The reflectometer has the capability of positioning the sample to 10 mu m and setting its angular position to 0.002 degrees. LABVIEW(TM) based software provides a convenient interface to the user. The reflectometer is separated from the beamline by a differential pump, and can be pumped down in 1/2 hour. Auxiliary experimental stations can be mounted behind the reflectometer. Results are shown which demonstrate the performance and operational convenience of the beamline.