Atmospheric pressure chemical vapor deposition of titanium aluminum nitride films

The atmospheric pressure chemical vapor deposition of titanium aluminum nitride films was accomplished using a three-precursor system comprised of titanium tetrachloride, tert-butylamine, and trimethylaluminum at a substrate temperature of 600 degrees C. Smooth, specular, and highly adherent violet-black films were obtained. The aluminum content of the films varied with trimethylaluminum flow rate up to a maximum aluminum/titanium ratio of about 1:1. Higher aluminum flow rates afforded rough, poorly adherent coatings. Films having the compositions Ti0.83Al0.17N0.89, Ti0.69Al0.31N0.85, and Ti0.52Al0.48N1.38 were analyzed in detail. The films were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, scanning electron microscopy, atomic force microscopy, and resistivity measurements. The films were subjected to nanoindentation hardness testing and high-temperature oxidation studies. The Ti1-xAlxN films were found to be harder and more resistant to oxidation by ambient atmosphere than TiN films deposited from titanium tetrachloride and tert-butylamine at 600 degrees C. The dependence of the film properties on the aluminum content is discussed.