Fabrication of Ultra-Thick Masks for X-ray Phase Contrast Imaging at Higher Energy

Published

February 16, 2025

Author(s)

Daniel Josell, Alessandro Rossi, Sandro Olivo, ioannis Papakonstantinou, Ian Buchanon, Alberto Astolfo, Anton Charman, Daniel Briglin

Abstract

X-ray phase contrast imaging (XPCI) provides higher sensitivity to low absorbing objects that can be invisible to conventional attenuation-based X-ray imaging. This technique's main application has been so far mostly focused on medical areas at relatively low X-rays energies (<100 keV). The translation to higher energy for industrial applications, where energies above 150 keV are often needed, is hindered by the lack of masks/gratings with sufficiently thick gold septa. The fabrication of such structures with apertures several tens of microns wide becomes difficult at depths higher than a few hundreds of micrometers due to aspect ratio dependent effects. At aspect ratios (AR) higher than 10, etching easily lacks anisotropy and a preferential deposition of metals (e.g., Au) occurs at the top of the apertures. In this work, these difficulties are overcome by Deep Reactive Ion Etching (DRIE) following a stepped parameters approach and Bismuth-mediated superconformal filling of Au, ultimately resulting in 500 µm deep Si masks filled with Au at bulk density. The obtained masks, tested in an Edge Illumination XPCI system with a conventional X-ray source and a photon counting detector, show good agreement with simulations at different energy thresholds and higher phase sensitivity for highly absorbing objects compared to previously available masks, proving their potential for industrial non-destructive testing and other areas requiring high X-ray energies such as security inspections.

Citation

Advanced Materials Interfaces

Pub Type

Journals

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https://doi.org/10.1002/admi.202400749

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Keywords

gold electrodeposition, gratings, imaging, superconformal

Citation

Josell, D. , Rossi, A. , Olivo, S. , Papakonstantinou, I. , Buchanon, I. , Astolfo, A. , Charman, A. and Briglin, D. (2025), Fabrication of Ultra-Thick Masks for X-ray Phase Contrast Imaging at Higher Energy, Advanced Materials Interfaces, [online], https://doi.org/10.1002/admi.202400749, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958455 (Accessed May 20, 2025)