Several techniques are described for reducing or mitigating the formation
of seams and/or voids in electroplating the interior regions of microscopic recessed
features. Cathodic polarization is used to mitigate the deleterious effects of
introducing a substrate plated with a seed layer into an electroplating solution.
Also described are diffusion-controlled electroplating techniques to provide for
bottom-up filling of trenches and vias, avoiding thereby sidewalls growing together
to create seams/voids. A preliminary plating step is also described that plates
a thin film of conductor on the interior surfaces of features leading to adequate
electrical conductivity to the feature bottom, facilitating bottom-up filling.