Copper aluminum oxide thin films were prepared by the plasma-enhanced chemical vapor deposition from metal organic precursors. The film was characterized by x-ray diffraction, atomic force microscopy, and the depth profile analysis using, secondary ion mass spectrometry. Nanoindentation was performed to measure the hardness and elastic modulus of the film. The mechanical strengthening of the film was considered to be due to nanograins of CuAlO2 and CuO throughout the film, the large area of grain boundaries, and also finer Al2O3 particles dispersed in the film matrix. (c) 2006 American Vacuum Society.