Using E-Beam and X-Ray Lithography Techniques to Fabricate Zone Plates for Hard X-ray

摘要

A high-resolution zone plate for focusing and magnifying hard-x-rays require very high fabrication precision and high aspect ratio metal structures and therefore post perhaps the most challenging task to the nanofabrication. We present a nanofabrication strategy to fabricate such devices for x-ray applications which takes advantage of the state-of-the-art x-ray lithography and electroplating processes. The substrate used to fabricate the x-ray mask is first prepared by depositing Si3N4 film on a Si wafer. Electron beam lithography capable of writing small lines (<10nm on photoresist) is then used to create desired zone plate pattern. An Au layer is electrodeposited into nano-paterned photoresist structure of sufficient thickness and the resist is then removed to expose the Au zone plate structure. Finally, the KOH is used to etch the Si wafer down to the Si3N4 film and to produce the desired x-ray hard mask. This hard mask defines the zone plate pattern with the x-ray lithography method. We demonstrate that the mask prepared by this method is of very high precision—30nm outermost zone—can be obtained. X-ray lithography process is attempted with convincing results.