Exploring the Limits of Bottom-Up Gold Filling to Fabricate Diffraction Gratings

Published

November 27, 2019

Author(s)

Daniel Josell, Stephen J. Ambrozik, Maureen E. Williams, A E. Hollowell, Christian Arrington, Shinichiro Muramoto, Thomas P. Moffat

Abstract

Gold deposition on rotating disk electrodes, Bi3+ adsorption on planar Au films and superconformal Au filling of trenches up to 45 m deep are examined in Bi+3-containing Na3Au(SO3)2 electrolytes with pH between 9.5 and 11.5. Higher pH is found to increase the potential-dependent rate of Bi adsorption on planar Au surfaces, shortening the incubation period that precedes active Au deposition on planar surfaces and bottom-up filling in patterned features. Decreased contact angles between the Au seeded sidewalls and bottom-up growth front also suggest improved wetting. The bottom-up filling dynamic in trenches is, however, lost at pH 11.5. The impact of Au concentration, 80 mmol/L versus 160 mmol/L Na3Au(SO3)2, on bottom-up filling is examined in trenches up ≈ 210 m deep with aspect ratio of depth/width ≈ 30. The microstructure of void-free, bottom-up filled structures characterized by scanning electron microscopy (SEM) and Electron BackScatter Diffraction (EBSD), revealing marked spatial variation of the grain size and orientation within the filled features.

Citation

Journal of the Electrochemical Society

Pub Type

Journals

Keywords

gold, grating, trenches, superfill

Citation

Josell, D. , Ambrozik, S. , Williams, M. , Hollowell, A. , Arrington, C. , Muramoto, S. and Moffat, T. (2019), Exploring the Limits of Bottom-Up Gold Filling to Fabricate Diffraction Gratings, Journal of the Electrochemical Society (Accessed October 21, 2025)