Nanofabrication of high aspect ratio 24 nm x-ray zone plates for x-ray imaging applications

Building high-performance zone plate is a critical step for achieving nanometer resolution in advanced x-ray imaging and microscopy. Zone plates with smaller outmost zone width and higher aspect ratio are increasingly in demand, simply because the resolution and efficiency of an x-ray microscope are ultimately determined by these two features. In this paper, we will present detailed discussion of achieving high aspect ratio and high resolution x-ray zone plate through electron beam lithography, trilevel resist process and gold plating, fabrication problems, and limitations. We will also present the technique to double the aspect ratio of the zone plate and measure the results of x-ray diffraction efficiency of single and aspect ratio doubled zone plates. (c) 2007 American Vacuum Society.