Abstract: Embodiments of the invention provide methods for reducing formation of void-type defects on the surface of a substrate during electrochemical plating. Embodiments of the invention provide methods to improve the wetting of a substrate surface prior to immersion and thereby minimize adhesion of bubbles to the substrate surface during immersion. A thin uniform metal oxide is formed on a metal layer on the substrate immediately prior to substrate immersion. In one aspect, exposing the substrate to an oxygen-containing gas, e.g. air, forms the metal oxide. The oxygen-containing gas may be flowed over the substrate or the substrate may be rotated at a high rate in the presence of an oxygen-containing gas. In another aspect, non-uniform metal oxides are first removed from the substrate in an anneal process and a thin uniform metal oxide is subsequently re-formed. An optimized substrate immersion method may also be used to further reduce void defects.