Mechanism for interfacial adhesion strength of an ion beam mixed Cu/polyimide with a thin buffer layer

A Cu (400 Angstrom)/Al (50 Angstrom)/polyimide system showed larger adhesio n strength than that of Cu (400 Angstrom)/polyimide after N-2(+) ion beam m ixing. X-ray emission spectroscopy was performed to elucidate the mechanism of adhesion enhancement of the ion beam mixed Cu (400 Angstrom)/polyimide with a thin Al buffer layer. Cu L-2,L-3 x-ray emission spectra showed the f ormation of a CuAl2O4 layer which is strongly correlated with the large adh esion strength of a Cu/Al/polyimide. A decrease in adhesion strength at an ion dose higher than 5 x 10(15) cm(-2) was also explained by the formation of an amorphous carbon. This was understood by investigating C K alpha x-ra y emission spectra. The overall spectroscopic results were in accordance wi th the behavior of quantitative adhesion strength. (C) 1999 American Instit ute of Physics. [S0003-6951(99)00404-0].