The embodiments fill the need to enhance electro-migration performance, provide lower metal resistivity, and improve metal-to-metal interfacial adhesion for copper interconnects by providing improved processes and systems that produce an improved metal-to-metal interface, more specifically barrier-to-copper interface. An exemplary method of preparing a substrate surface of a substrate to deposit a metallic barrier layer to line a copper interconnect structure of the substrate and to deposit a thin copper seed layer on a surface of the metallic barrier layer in an integrated system to improve electromigration performance of the copper interconnect is provided. The method includes cleaning an exposed surface of a underlying metal to remove surface metal oxide in the integrated system, wherein the underlying metal is part of a underlying interconnect electrically connected to the copper interconnect. The method also includes depositing the metallic barrier layer to line the copper interconnect structure in the integrated system, wherein after depositing the metallic barrier layer, the substrate is transferred and processed in controlled environment to prevent the formation of metallic barrier oxide. The method further includes depositing the thin copper seed layer in the integrated system, and depositing a gap-fill copper layer over the thin copper seed layer in the integrated system. An exemplary system to practice the exemplary method described above is also provided.