Bottom-up Gold Filling of Sub-Micrometer Trenches

A Bi 3 + -stimulated Au electrodeposition process in slightly alkaline Na 3 Au SO 3 2 + Na 2 SO 3 electrolytes has been previously demonstrated for void-free bottom-up filling of progressively deeper and higher aspect trenches in gratings for advanced X-ray imaging technologies. The present work extends this bottom-up Au filling phenomenon to improve filling of small trenches. In particular, electrolytes are examined to reduce passive deposition on the sidewalls, demonstrating the feasibility of filling high aspect ratio features well into the sub-micrometer range. Improved Au fill in dense 1 μm pitch gratings with V-shaped trenches is detailed.