Effects of growth and postgrowth parameters on the microstructure and copper distribution in Al(Cu)/SiO2 thin films

Rutherford backscattering spectroscopy (RBS), x-ray diffraction (XRD), and transmission electron microscopy (TEM) have been employed to study sputter-deposited Al(Cu)/SiO2 films with as low as 0.2 at.% concentration of copper at the wafer target. It is shown that (1) copper concentration is not uniform throughout the film and (2) copper is depleted near the Al/SiO2 interface. The nonuniformity of copper at the interface has been discussed in terms of grain boundaries, their dynamics under film-growth conditions, and the nonuniformity’s consequences in microelectronic device fabrications.