Barrier layer and annealing temperature dependent microstructure evolution of nanocrystalline Cu films

The effects of barrier layers and annealing temperature on texture variation, grain growth and void forming of nanocrystalline Cu films were investigated by X-ray diffraction, transmission electron microscope and scanning electron microscope (SEM). The variation in texture and grain size of Cu films with annealing temperature is different for Cu/Ti and Cu/Ta. The activation energies of grain growth of Cu films on Ti and Ta, respectively, are 19.7 and 23.4 kJ mol−1, which are much closer to that of grain boundary diffusion of Cu. The average diameter of about 400 nm for surface voids of Cu/Ti is larger than that of Cu/Ta structure. Furthermore, both the electrical resistivity measurement and SEM observation imply that Cu/Ti rather than Cu/Ta structure tend to fail easier as annealing temperature exceed 400 °C.