The desorption / adsorption of suppressor additive during Cu electroplating plays a critical role in the void-free filling of recessed features such as through-silicon vias (TSVs) used in 3-dimensional integration. A stochastic model was proposed for Polyethylene Glycol (PEG) as a suppressor additive in Cu electroplating. Using the proposed model, a program capable of simulating transient processes such as cyclic voltammograms (CVs) was developed. The steep change of current density due to suppressor desorption, as well as the characteristic hysteresis, observed in the CVs was shown in simulation. The dependency of PEG desorption / adsorption on various factors, including the bath composition, scan rate and molecular weight, was simulated. The simulation results were confronted side-by-side with the corresponding experimental measurements. An overall good qualitative match was shown. (C) 2014 The Electrochemical Society. All rights reserved.