2016Microelectronic engineering 152, 6 - 9(2016). doi:10.1016/j.mee.2015.12.015We present an improved nanofabrication method of high aspect ratio tungsten structures for use in high efficiency nanofocusing hard X-ray zone plates. A ZEP 7000 electron beam resist layer used for patterning is cured by a second, much larger electron dose after development. The curing step improves pattern transfer fidelity into a chromium hard mask by reactive ion etching using Cl2/O2 chemistry. The pattern can then be transferred into an underlying tungsten layer by another reactive ion etching step using SF6/O2. A 630 nm-thick tungsten zone plate with smallest line width of 30 nm was fabricated using this method and characterized. At 8.2 keV photon energy the device showed an efficiency of 2.2% with a focal spot size at the diffraction limit, measured at Diamond Light Source I-13-1 beamline.Published by Elsevier, [S.l.]10.3204/PUBDB-2016-05566en2016Deutsches Elektronen-Synchrotron, DESY, Hamburg10.1016/j.mee.2015.12.0150167-93171873-5568Journal articlepages 6 - 9620Improved tungsten nanofabrication for hard X-ray zone platesParfeniukas, KarolisRahomäki, JussiGiakoumidis, StylianosSeiboth, FrankWittwer, FelixDeutsches Elektronen-SynchrotronSchroer, Christian0000-0002-9759-1200Deutsches Elektronen-SynchrotronVogt, Ulrich