Additives for Superconformal Gold Feature Filling

Published

May 11, 2021

Author(s)

Daniel Josell, Thomas P. Moffat

Abstract

An overview of the effect of additives on Au electrodeposition from Na3Au(SO3)2 based electrolytes is presented with an emphasis on filling of fully metallized recessed surface features such as trenches and vias. The impact of heavy metals additives Tl+, Pb2+, and Bi3+ is reviewed and accompanied by a brief survey of the effects of Sb3+, Te4+, SeCN-, 3-mercapto-1-propanesulfonic acid (MPS) and polyethyleneimine (PEI) additions. The addition of Tl+, Pb2+, Bi3+ or Sb3+ accelerates the kinetics of Au(SO3)23- reduction to Au, as manifest in hysteretic voltammetry and rising chronoamperometric transients, and yields bright specular deposits. Gold deposition with Pb2+ addition exhibits superconformal filling in sub-micrometer trenches while Bi3+ addition induces a more extreme bottom-up filling, but Tl+ and Sb3+ additions yield essentially conformal deposition for the conditions examined. Modest acceleration and hysteresis observed with Te4+ addition reflect roughening due to limited nucleation, 3D growth and delayed coalescence, rather than catalysis, and are associated with conformal feature filling. Unlike the other additives, SeCN-, MPS and PEI inhibit the deposition kinetics. Breakdown of suppression during deposition in micrometer size trenches is biased toward recessed surfaces where the flux of suppressor is constrained, yielding localized deposition and superconformal filling.

Citation

Journal of the Electrochemical Society

Volume

168

Pub Type

Journals

Download Paper

https://doi.org/10.1149/1945-7111/ abfcd7

Local Download

Keywords

gold, electrodeposition, superconformal, trenches, gratings

Citation

Josell, D. and Moffat, T. (2021), Additives for Superconformal Gold Feature Filling, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/1945-7111/ abfcd7, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932124 (Accessed April 28, 2024)