Semiconductor devices include a patterned dielectric layer overlaying a semiconductor substrate; a metal layer comprising copper disposed in the patterned dielectric layer; and a barrier layer formed at an interface between the dielectric layer and the metal layer, wherein the barrier layer is AlOxNy. The patterned dielectric may define a trench and via interconnect structure or first and second trenches for a capacitor structure. Also disclosed are processes for forming the semiconductor device, which includes subjecting the dielectric surfaces to a nitridization process to form a nitrogen enriched surface. Aluminum metal is then conformally deposited onto the nitrogen enriched surfaces to form AlOxNy at the aluminum metal/dielectric interface. The patterned substrate is then metalized with copper and annealed. Upon annealing, a copper aluminum alloy is formed at the copper metal/aluminum interface.