Fabrication of multilayer optics by sputtering: application to EUV optics with greater than 30% normal reflectance

A planar diode, rf-sputtering system, modified to triode operation by addition of a ring filament surrounding the anode, is described. Alternately timed sputtering is used to fabricate multilayer films with good characteristics, predominantly in the extreme ultraviolet (EUV) range of 15 to 20 nm. Fabrication of stable films of niobium/silicon is discussed, along with characterization results that utilized x-ray diffraction (XRD) and synchrotron source reflectance measurements. Characteristics of an optic that was designed and used to photograph the sun at 18.0 nm from a rocket-borne experiment are described.