Cu (400 Å)/polyimide was mixed with 80 keV Ar+and N2+from 1.0×1015to 2.0×1016ions/cm2. The same processes were repeated for the Cu (400 Å)/Al (50 Å)/polyimide system which has Al as a buffer layer. The quantitative adhesion strength was measured by a standard scratch test. X-ray photoelectron spectroscopy was employed to investigate the change in the chemical bonds of the ion beam mixed polyimide substrate and the intermediate effects for the adhesion enhancement in Cu/Al/polyimide. Two distinct tendencies are observed in the adhesion strength: Cu/Al/polyimide is more adhesive than Cu/polyimide after ion beam mixing, and N2+ions are more effective in the adhesion enhancement than Ar+. The formation of an interlayer compound of CuAl2O4accounts for the former, while the latter is understood by the fact that N2+ions produce more pyridinelike moiety, amide group and tertiary amine moiety which are known as adhesion promoters. ©1997 American Institute of Physics.