Three-Additive Model of Superfilling of Copper

Abstract

A model describing the effect of an accelerator bis(3-sulfopropyl)disulfide (SPS) and the two inhibitors poly(ethylene glycol) and Janus Green B (PEG and JGB) on the leveling efficacy on submicrometer trenches of an acid-copper plating bath is described, simulated, and compared to experimental fill studies. All parameters of the model are estimated from electrochemical measurements on a nonpatterned, rotating disk electrode. A multicomponent version of a Frumkin isotherm is employed to account for the interaction between SPS and PEG, and the interaction between PEG and JGB are described by a competitive adsorption, Langmuir model. Shape-change simulations employing these descriptions of the surface phenomena are consistent with fill studies over a large range of SPS and JGB concentrations; however, simulations do not predict the result that void-free deposits are achieved when the concentration of JGB is zero. © 2001 The Electrochemical Society. All rights reserved.