Fabrication of high energy X-ray compound kinoform lenses using X-ray lithography

Abstract

Nickel high energy X-ray compound kinoform lenses were fabricated by X-ray lithography technology at Beijing Synchrotron Radiation Facility. The nickel compound refractive lenses aim at focusing X-ray with 50 keV and the designed smallest width of the tooth-like segment is 2.5 μm. To keep the best morphology of the element, Au masks were made twice, whose thickness gradually increased. The fabrication process of compound lenses consists of three parts in general, including the intermediate mask (1.2 μm thick Au pattern) fabrication, the working mask (12 μm thick Au pattern) fabrication and the 300 μm high lenses fabrication. The intermediate mask was made by UV lithography (UV sample) and electron beam direct write lithography (EBDW sample) for comparison, and the EBDW sample had a better morphology than the UV sample at each step. Both samples were tested using the knife-edge scan method at BL13W1 beamline in Shanghai Synchrotron Radiation Facility, which provided the focal widths of 9.2 and 10.4 μm, and the photon flux gains of 6.9 and 5.4 for the EBDW and UV samples at an X-ray energy with 50 keV, respectively.