Research On Soft X-ray Condenser Zone Plates

Because of advantages such as high resolution, a natural contrast for samples containing carbon in water, and the soft x-ray energy matching the absorb line of many elements, soft X-ray microscopies have many important applications in life science, environmental science and physics. X-ray condenser zone plates (CZP) focalize and disperse X-ray, and x-ray micro zone plates (MZP) serve as the imaging component for the sample, which are both the key components in soft X-ray microscope. This dissertation was aimed at this background, and the main motivation was to fabricate soft X-ray CZP with longer life and higher efficiency for the transmission soft X-ray microscope in the National Synchrotron Radiation Laboratory. The main problems in the fabrication of X-ray CZP are investigated, and the fabrication processes are presented. The relative efficiencies between phase CZP and amplitude CZP are measured.The development of soft X-ray CZP included design of optical path, selection of material, preparation of thin film, sub-micron lithography, X-ray lithography, reactive ion etching, ion beam etching, electroplating and chemical etching.We integrally investigated the fabrication of holographic Soft X-ray CZP, and suggested the full process of the fabrication of soft X-ray CZP, and the measurement of relative efficiency between phase zone plates and an amplitude zone plate was also carried out.The main works of this thesis can be summarized as follows:(1) Fabrication of soft X-ray self-supporting (or free-standing) condenser zone plates. The main characterization of a self-supporting zone plate is to use not membrane but metal struts to support the zones. This kind of zone plate has a longer life than the zone plates with membrane substrate under radiation. We used laser holography-ion beam etching technology fabricated Au condenser zone plates with polyimide substrate, and the Au zone plates was employed as the mask of synchrotron radiation lithography, and then we used ion beam etching technology to obtain metal a zone plate pattern. Lastly, the Au support struts are fabricated by micro electroplating.(2) Fabrication of Ni and Ge X-ray phase condenser zone plates. X-ray phase zone plates have higher efficiencies than amplitude zone plates. In common use, the Ge zone plates with high aspect ratio can be fabricated by fluoride gases, and the Ni zone plates with high aspect ratio can be fabricated by nickel low stress electroplating. If the aspect ratio of a zone plate is high, silicon nitride membrane can be employed as substrate. High compressive silicon nitride membrane should be used when Ge is evaporated on the membrane, and low stress silicon nitride membrane should be used when fabricating Ni zone plate pattern by electroplating. The matching of the stress of polyimide membrane is easier because of its very good elasticity, and considering the condenser zone plates we fabricated are with low aspect ratio, so we used synchrotron radiation lithography-ion beam etching...