Electromigration and stress migration of Cu interconnects are significantly reduced by forming a composite capping layer comprising a layer of tantalum nitride on the upper surface of the inlaid Cu and a layer of .alpha.-Ta on the titanium nitride layer. Embodiments include forming a recess in an upper surface of an upper surface of Cu inlaid in a dielectric layer, depositing a layer of titanium nitride of a thickness of 20 .ANG. to 100 .ANG. and then depositing a layer of .alpha.-Ta at a thickness of 200 .ANG. to 500 .ANG..