The effect of deposition parameters and substrate surface condition on texture, morphology and stress in magnetron-sputter-deposited Cu thin films

Cu films, 5 and 500 nm thick, were sputtered onto amorphous SiO2 and Si3N4 substrates. The dependence of the film properties on the deposition pressure and the type and cleaning conditions of the substrate was investigated by Atomic Force Microscopy (AFM), Focused Ion Beam (FIB) Microscopy and X-ray diffraction (XRD). Cleaning the substrate leads to a smaller island size for the 5-nm-thick films, to the development of a columnar microstructure for the 500-nm-thick films and to a more pronounced {111} fiber texture for the Cu films on Si3N4 substrates. The tensile growth stress at the coalescence stage of the 5-nm-thick films reversed to compressive in the 500-nm-thick films owing to stress relief and to atomic peening. Sharper texture correlates with higher microstrain. Postdeposition annealing results in a more pronounced texture, grain growth and relaxation of the growth stress and the microstrain.