A method for post-etching treatment of copper interconnecting wires that are used to electrically couple an upper interconnecting layer with a lower interconnecting layer includes forming the lower interconnecting layer on a substrate, and forming the upper interconnecting layer on the lower interconnecting layer. The lower interconnecting layer includes a first dielectric layer, a plurality of wire trenches formed in the first dielectric layer and being filled with copper, and a first top barrier layer overlying the first dielectric layer and the wire trenches. The upper interconnecting layer includes a second dielectric layer on the top barrier layer, and a plurality of vias extending through the second dielectric layer and the top barrier layer and exposing the copper in the wire trenches. The method further includes treating the exposed copper using a plasma process comprising NH3.