Fabrication of Small Linewidth Diffractive Optics for Use with Soft X-Rays

Abstract

Recently there has been much interest in the development and use of soft x-ray microscopy, as other contributions to this volume show. In the United Kingdom, a soft x-ray microscopy program is being carried out on the Synchrotron Radiation Source at the Daresbury Laboratory [12.1]. Although it is intended ultimately to develop a scanning microscope, the initial stages of the program have concentrated on the construction of high-resolution optical components for use in a prototype imaging microscope. For this purpose a lithographic technique using a Vacuum Generators HB5 scanning transmission electron microscope (STEM) is being used. This technique is capable of drawing accurate patterns, with linewidths much less than 50 nm, over small areas. It is therefore suitable for the manufacture of soft x-ray diffractive optics, in particular zone plates. This is discussed in this paper, as are the effects of possible manufacturing inaccuracies on the zone plate imaging properties. Deliberate modifications to the Fresnel zone plate are also considered.