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

Published

September 30, 2020

Author(s)

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

Abstract

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.

Citation

Journal of the Electrochemical Society

Volume

167

Pub Type

Journals

Download Paper

DOI Link

Keywords

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

Citation

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], https://doi.org/10.1149/1945-7111/ abba63 (Accessed September 17, 2024)