Superconformal Electrodeposition of Copper in 500-90 nm Features
Thomas P. Moffat, Daniel Wheeler, W H. Huber, Daniel Josell
Superconformal electrodeposition of copper in 500 nm deep trenches ranging from 500 to 90 nm in width has been demonstrated using an acid cupric sulfate electrolyte containing chloride (C1), polyethylene glycol (PEG), and 3-meracapto- 1propanesulfonate (MPSA). In contrast, similar experiments using either an additive-free electrolyte, or an electrolyte containing the binary combinations C1-PEG, C1-MPSA, or simply benzotriazole (BTAH), resulted in the formation of a continuous void within the center of the trench. Void formation in the latter electrolytes is shown to be reduced through the geometrical leveling effect associated with conformal deposition in trenches or vias with sloping sidewalls. The slanted sidewalls also counterbalance the influence of the differential cupric ion concentration that develops within the tranches. Examination of the i-E deposition characteristics of the electrolytes reveals a hysteretic response associated with the C1-PEG-MPSA electrolyte that can be usefully employed to monitor and explore additive efficency and consumption. Likewise, resistivity measurements performed on corresponding blanket films can be used to quantify the extent of additive incorporation and its influence on microstructural evolution. The films deposited from the C1-PEG-MPSA electrolyte exhibit spontaneous recrystallization at room temperature that results in a 23% drop in resistivity within a few hours of deposition.
, Wheeler, D.
, Huber, W.
and Josell, D.
Superconformal Electrodeposition of Copper in 500-90 nm Features, Journal of the Electrochemical Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852990
(Accessed November 29, 2023)