Preparation of (Ti1-xAlx)N films from mixed alkoxide solutions by plasma CVD

(Ti1-xAlx)N films were prepared on a Si wafer at 700 degrees C from toluene solution of alkoxides (titanium tetraetoxide and aluminum tri-butoxide) in an Ar/N-2/H-2 plasma by the thermal plasma chemical vapor deposition (CVD) method. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electrical resistivity, and Vickes micro-hardness. Single phase TiN formed at an Al atomic fraction of 0-0.2, with a mixed TiN and AIN phase occurring up to 0.6 and single phase A1N forming above 0.8. The films had relatively sooth surfaces, 0.4 mu m thick at an Al atomic fraction of 0.2, and thickened with increasing Al fraction. The atomic concentration of Ti, Al, N, O, and C determined from their respective XPS areas showed that the Ti and Al contents of the films changes with the solution composition in a complementary way. The impurities were about 10 at.% oxygen and carbon. The electrical resistivity was almost unchanged from the value of 10(3) mu Omega cm at 0-0.6 Al but then suddenly increased to 10(4) mu Omega cm at higher Al contents. The hardness showed a synergic maximum of about 20 GPa at an Al fraction of 0.6-0.8. (C) 2000 Elsevier Science S.A. All rights reserved.