Higher initial number of copper nucleation sites on a substrate surface may have substantial benefits. For example, in the process of copper deposition, copper nuclei may start growing initially from the palladium sites in all directions (3D growth). As deposition progresses, individual nuclei may coalesce into a continuous film, and the film may continue growing uniformly into the 2D growth phase. The uniformity of the electroless copper film may be related to the initiation phase that depends on factors described before including favorable catalytic sites for initial seeding. Typically, higher number of palladium sites may provide for faster coalescence of copper nuclei in the initiation phase and subsequent transition from 3D to 2D growth, resulting in improved thickness uniformity of the resulting plated copper film.