Journal article
Optimizing shape uniformity and increasing structure heights of deep reactive ion etched silicon x-ray lenses: Paper
DTU Danchip, Technical University of Denmark1
European Synchrotron Radiation Facility2
Department of Physics, Technical University of Denmark3
Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark4
Surface Physics and Catalysis, Department of Physics, Technical University of Denmark5
Department of Micro- and Nanotechnology, Technical University of Denmark6
Silicon Microtechnology, Department of Micro- and Nanotechnology, Technical University of Denmark7
Line-focusing compound silicon x-ray lenses with structure heights exceeding 300 μm were fabricated using deep reactive ion etching. To ensure profile uniformity over the full height, a new strategy was developed in which the perimeter of the structures was defined by trenches of constant width. The remaining sacrificial material inside the lens cavities was removed by etching through the silicon wafer.
Since the wafers become fragile after through-etching, they were then adhesively bonded to a carrier wafer. Individual chips were separated using laser micro machining and the 3D shape of fabricated lenses was thoroughly characterized by a variety of means. Optical testing using synchrotron radiation with a photon energy of 56 keV yielded a 300 μm wide beam with a waist of 980 nm (full width at half maximum) at a focal length of 1.3 m.
Optical aberrations are discussed in the context of the shape analysis, where a slight bowing of the lens sidewalls and an insufficiently uniform apex region are identified as resolution-limiting factors. Despite these, the proposed fabrication route proved a viable approach for producing x-ray lenses with large structure heights and provides the means to improve the resolution and capabilities of modern x-ray techniques such as x-ray microscopy and 3D x-ray diffraction.
Language: | English |
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Year: | 2015 |
Pages: | 125013 |
ISSN: | 13616439 and 09601317 |
Types: | Journal article |
DOI: | 10.1088/0960-1317/25/12/125013 |
ORCIDs: | Stöhr, Frederik , Michael-Lindhard, Jonas , Hübner, Jörg , Jensen, Flemming , Hansen, Ole and Poulsen, Henning Friis |