X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and thin-film X-ray diffraction (TF-XRD) have been used to investigate the oxidation-resistant property of the plasma-treated copper. From the XPS and AES results, it is possible to confirm the successful incorporation of the C and N into copper matrix using plasma treatment. Thick;ness measurements from AES depth profiles confirm the dominant influence the film thickness has on the enhanced oxidation resistance of the plasma-treated copper as compared to the small difference in film stoichiometry. TF-XRD analysis on the various heated samples shows the progressive Formation of the cuprous oxide (Cu2O) and cupric oxide (CuO) as a function of heating temperature. Also, the threshold of the copper oxidation or oxidation resistance window has been enlarged by the plasma treatment. The variation in oxidation resistance of the films con be ascribed to the incorporation of the C and N into the films as well as the thickness of the films since the composition and distribution of the C and N in the films play a very important role in oxidation resistance.