High Resolution Germanium Zone Plates and Apertures for Soft X-Ray Focalometry

Circular Fresnel zone plates, apodized linear zone plates, and a variety of apertures have been fabricated in smooth germanium films deposited on boron doped silicon membranes. Minimum zone widths down to 60 nm have been achieved using electron beam lithography in a tri-level resist followed by reactive ion etching to transfer the patterns. These optical elements are the key components in a soft x-ray focalometer currently being tested at the NSLS at Brookhaven. The main purpose of this system is to evaluate the surface figure of convergent mirrors both with and without reflective coatings for use at soft x-ray wavelengths (~10 nm). While the materials and fabrication methods of these components is central to this report, preliminary results obtained at 13 nm using this system for an uncoated and therefore low reflectivity mirror will also be presented.