A novel method for the activation of semiconductor substrates for highly selective electroless copper plating in multilayer interconnect metallization lines and vias/contact holes has been developed. A copper-seeded polysilicon layer is provided over the substrate to facilitate growth of copper into the vias. Subsequent rinsing and chemical-mechanical polishing processes allow removal of overgrowth of copper and the polysilicon layer to achieve overall smooth topography of the copper surface and the insulating layer surface of the substrate.