Thermal and ion beam induced thin film reactions in Cu-Al bilayers

Abstract Thermal and ion beam induced thin film reactions in Cu-Al bilayers were investigated by Rutherford backscattering and X-ray diffraction. A marker experiment was performed to study the moving species during the reaction using W embedded in the interface. At the initial stage of the thermally induced reaction, CuAl 2 , which is the most Al rich phase in the Cu-Al system, was observed to nucleate after annealing at 220°C for 30 min. Al was the dominant moving species during CuAl 2 phase growth. The diffusion of Cu was enhanced as the temperature increased, which resulted in the formation of Cu 9 Al 4 as the second phase. The diffusion of Cu became dominant at temperatures above 240°C. In ion beam mixing, on the other hand, the CuAl 2 phase was not observed to form. The Cu 9 Al 4 phase nucleated from the beginning of the reaction.