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Pushing the Limits of Bottom-Up Gold Filling for X-Ray Grating Interferometry



Daniel Josell, Thomas P. Moffat, Z Shi, K Jefimovs, L Romano, J. Vila-Comamala


The application of superconformal Bi-catalyzed Au electrodeposition for void-free filling of recessed trenches in X-ray gratings used in phase contrast imaging is detailed. Filling of trenches with aspect ratio (height divided by its width) up to 55 is demonstrated. Uniform bottom-up filling of patterned trench arrays across a 4 inch (10 cm) diameter Si wafer is accomplished using a well defined hydrodynamic flow field across the wafer surface. The filling process and microstructure are examined by scanning electron microscopy of cross-sectioned specimens. The importance of process optimization, from the design of potential (current) programming to electrolyte pH and concentrations of Na3Au(SO3)2 and Bi3+, for the filling of high aspect ratio trenches is demonstrated. X-ray phase contrast imaging is used to assay the quality and uniformity of the as-formed gratings as well as demonstrate their application to imaging biological tissue. Successful void-free Au filling of micrometer pitch, high aspect ratio trenches in Si gratings promises to advance X-ray grating interferometry and its application to X-ray phase contrast imaging.
Journal of the Electrochemical Society


grating, medical imaging, imaging, gold, superconformal, superfill, trenches


Josell, D. , Moffat, T. , Shi, Z. , Jefimovs, K. , Romano, L. and Vila-Comamala, J. (2020), Pushing the Limits of Bottom-Up Gold Filling for X-Ray Grating Interferometry, Journal of the Electrochemical Society, [online], abba63 (Accessed April 20, 2024)
Created September 30, 2020, Updated January 25, 2023