The object of the present invention is a method and compositions for direct copper plating and filling to form interconnects in the fabrication of semiconductor devices.According to the invention, this method comprises: providing an electrolytic copper bath containing, in solution in a solvent, a source of copper ions with a concentration of between 45 and 200 mM, preferably of between 45 and 100 mM and at least one copper complexing agent which is an aliphatic polyamine having 2 to 4 amine functions with a concentration of between 30 and 200 mM, preferably of between 60 and 200 mM; the copper/complexing agent(s) molar ratio being of between 0.2 and 2, preferably between 0.3 and 1.5; bringing said copper diffusion barrier layer of said substrate into contact with said electrolytic copper bath, applying an electrical bias to the substrate for a duration adjusted according to the thickness of copper to be electroplated, removing the substrate from said electrolytic copper bath.