Electronic devices are constructed by a method that includes forming a first conductive layer in an opening in a multilayer dielectric structure supported by a substrate, forming a core conductive layer on the first conductive layer, subjecting the core conductive layer to a H.sub.2 plasma treatment, and depositing a capping adhesion/barrier layer on the core conductive layer after the H.sub.2 plasma treatment. The multilayer dielectric structure provides an insulating layer for around the core conducting layer and at least one sacrificial layer for processing. The H.sub.2 plasma treatment removes unwanted oxide from the surface region of the core conducting layer such that the interface between the core conducting layer and the capping adhesion/barrier is substantially free of oxides. In an embodiment, the core conducting layer is copper with a titanium nitride or zirconium capping adhesion/barrier layer.