Improved tungsten nanofabrication for hard X-ray zone plates
2016 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 152, 6-9 p.Article in journal (Refereed) PublishedText
We 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.
Place, publisher, year, edition, pages
2016. Vol. 152, 6-9 p.
High aspect ratio, Reactive ion etching, Tungsten, X-ray diffractive optics, Zone plate
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:kth:diva-180917DOI: 10.1016/j.mee.2015.12.015ScopusID: 2-s2.0-84952359520OAI: oai:DiVA.org:kth-180917DiVA: diva2:898484
QC 201601282016-01-282016-01-252016-01-28Bibliographically approved