Electrodeposition of copper in the presence of a multicomponent additives mixture, consisting of an inhibitor [e.g., poly(ethylene glycol)] and an accelerator [e.g., bis(3-sulfopropyl) disulfide] that is typically used in the "bottom-up" fill of submicrometer vias and trenches on semiconductor wafers, is analyzed. The additives transport, adsorption, and interactions are incorporated in a time-dependent multicomponent model that provides the additives distribution inside the via. The additives distribution is translated into location- and time-dependent copper deposition rates to simulate the via-fill process. All model parameters are based on experimentally measured transient copper deposition kinetics in the presence of additives. The effect of the local area reduction during the via fill on the additives distribution is incorporated into the simulations. The model indicates that the short time scale additives transport and adsorption processes provide a differential additives coverage between the via top and its bottom sufficient to initiate bottom-up growth. The long time-scale accelerator-inhibitor interactions in combination with the local area reduction effects provide further enhancement to the additives-induced differential plating rates. The latter generates the bottom-up deposition necessary for the "void-free" gap fill of high aspect ratio structures.