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Improved tungsten nanofabrication for hard X-ray zone plates

DOI: 10.1016/j.mee.2015.12.015 DOI Help

Authors: Karolis Parfeniukas (KTH Royal Institute of Technology) , Jussi Rahomaki (KTH Royal Institute of Technology) , Stylianos Giakoumidis (KTH Royal Institute of Technology) , Frank Seiboth (TU Dresden) , Felix Wittwer (DESY) , Christian G. Schroer (DESY) , Ulrich Vogt (KTH Royal Institute of Technology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Microelectronic Engineering , VOL 152 , PAGES 6 - 9

State: Published (Approved)
Published: February 2016
Diamond Proposal Number(s): 12046

Open Access Open Access

Abstract: 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.

Journal Keywords: X-ray diffractive optics; Zone plate; Tungsten; High aspect ratio; Reactive ion etching

Subject Areas: Engineering, Physics

Instruments: I13-1-Coherence