Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Poster Session I
DS 17.74: Poster
Tuesday, March 13, 2018, 18:15–20:15, Poster B
Materials Science of ALD Fresnel Zone Plates — •Umut T. Sanli1, Chengge Jiao2, Margarita Baluktsian1, Kersten Hahn3, Yi Wang3, Vesna Srot3, Gunther Richter1, Iuliia Bykova1, Markus Weigand1, Gisela Schütz1, and Kahraman Keskinbora1 — 1MPI for Intelligent Systems, Stuttgart — 2FEI, Eindhoven — 3MPI for Solid State Research, Stuttgart
X-ray microscopy is a very strong tool to investigate matter providing high penetration depths combined with structural, chemical and magnetic contrast. One of the most widely used X-ray optics is the Fresnel zone plate (FZP), particularly for ultrahigh resolution X-ray microscopy. A FZP is an alternating set of transparent and opaque concentric rings and its resolution is given by the width of its outermost zone. Currently, the direct imaging resolutions using FZPs have saturated to about 10 nm (in half-pitch). For lower values, wave-coupling effects dominate with a significant penalty to the diffraction efficiencies. One promising solution is to tilt the zones to the Bragg angle, which is a significant fabrication challenge. Hereby the material properties, which require a more stringent quality, are of critical importance since the zones must have a low roughness both radially and longitudinally and the interfaces must be chemically extremely smooth. Furthermore, the microstructure and morphology must be controlled to avoid diffuse scattering. Here we present a new fabrication route for FZP arrays with zones tilted to the Bragg angle by a combination of FIB pre-structuring and subsequent ALD. We demonstrate the quality of these optics and discuss their potential for sub-10 nm resolutions.