a method for post - etch copper cleaning uses a hydrogen plasma with a trace gas additive constituting about 3 - 10 percent of the plasma by volume to clean a copper surface exposed by etching . the trace gas may be atomic nitrogen or other species having an atomic mass of 15 or greater . the trace gas adds a sputtering aspect to the plasma cleaning and removes polymeric etch by - products and polymeric and other residuals formed during the deposition of dielectric materials or etch stop layers over the copper surface . an anti - corrosion solvent may be used to passivate the copper surface prior to formation of the dielectric materials or etch stop layers .