Superconformal Electrodeposition of Silver in Submicrometer Features

Abstract

The generality of the curvature-enhanced accelerator coverage (CEAC) model of superconformal electrodeposition is demonstrated through application to superconformal filling of fine trenches during silver deposition from a selenium-catalyzed silver cyanide electrolyte. The CEAC mechanism involves (i) increase of local metal deposition rate with increasing coverage of a catalytic species adsorbed on the metal/electrolyte interface and (ii) significant change of local coverage of catalyst (and thus local deposition rate) in submicrometer features through the changing area of the metal/electrolyte interface. Electrochemical and X-ray photoelectron experiments with planar electrodes (substrates) are used to identify the catalyst and obtain all kinetic parameters required for the simulations of trench filling. In accord with the model, the electrolyte yields optically shiny, dense films, hysteretic current-voltage curves, and rising current-time transients. Experimental silver deposition in trenches from 350 down to 200 nm wide are presented and compared with simulations based on the CEAC mechanism. All kinetics for the modeling of trench filling come from the studies on planar substrates. The results support the CEAC mechanism as a quantitative formalism for exploring morphological evolution during film growth. © 2002 The Electrochemical Society. All rights reserved.