Nano-fabrication of condenser and micro-zone plates for compact X-ray microscopy

Abstract

We demonstrate nano-fabrication of high-aspect ratio and high-spatial frequency diffractive X-ray optics with high uniformity for use in a laser-plasma-based compact water-window X-ray microscope. The structures are fabricated on 50 nm thin Si 3N 4-membranes using a three-layer resist scheme and 30 keV e-beam lithography in combination with reactive ion etching and nickel electroplating. The process is developed on solely commercially available resists and instruments. As examples, we demonstrate fabrication of micro-zone plates with outermost linewidths of 30 nm and an uniform zone height of 160 nm, and a 4.5 mm diameter condenser zone plate with 50–60 nm lines, fabricated by using stitched fields.