This work presents experiments and theory describing a mechanism for how brighteners in electrolytes function. The mechanism involves change of local coverage of a deposition rate-enhancing catalyst adsorbed on the surface through change of local surface area during growth as well as accumulation and consumption. A first-order perturbation analysis shows the surface is stable against growth of perturbations for all wavelengths below a critical value that is deposition-condition dependent. The model predictions are shown to be consistent with the experimental results.Roughness evolution during electrodeposition is a subject of wide-ranging scientific and technical interest. Experience has shown that metal ion depletion at the interface is usually associated with destabilization of planar growth fronts. This has been explained by Mullins-Sekerka morphological stability theory which examines system response to small perturbations from steady-state growth conditions. Typically, a sinusoidal variation of surface height is imposed on the flat surface, and the resulting time evolution, to first order in the amplitude of the perturbation, is analyzed. 1,2 A positive growth rate reflects instability while a negative value results in attenuation of the perturbation; the former yields a rough surface while the latter case gives a smooth interface. This type of analysis has been widely applied to study phase transformations ranging from solidification, 1,2 to additive-free electroplating, 3-11 and chemical vapor deposition. 12,13 In contrast to the destabilizing influence of the reactant gradient, it is known that capillarity, adatom diffusion, and reaction kinetics dampen, and even stabilize the system, particularly at shorter wavelengths.An important aspect of electroplating practice involves the use of electrolyte additives to generate smooth, optically bright films. In certain instances, additives even allow the leveling of undesired surface imperfections by inducing preferential deposition at the bottom of features such as scratches. The traditional leveling mechanism behind this process is the existence of a concentration gradient of the inhibiting additive that results in lower deposition of the inhibitor, with associated decreasing inhibition of the metal deposition, the farther down one goes in the defect. 14-17 It is generally known that electrolytes that otherwise deposit at equal rates on all surfaces can be induced to deposit preferentially at the bottoms of polishing scratches and other surface imperfections through the addition of deposition-rate inhibiting additives.It is generally recognized that the traditional leveling mechanism will not affect deposition substantially when the dimensions of the defect are orders of magnitude smaller than the thickness of the boundary layer responsible for the concentration gradient. For optically relevant dimensions that are only a fraction of 1 m and a typical boundary layer thickness of 100 m, the appropriateness of such a model becomes questionable. For this reason, el...

State-of-the-art manufacturing of semiconductor devices involves the electrodeposition of copper for on-chip wiring of integrated circuits.

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