X-RAY PHOTOELECTRON-SPECTROSCOPY AND TRANSMISSION ELECTRON-MICROSCOPY STUDIES OF THE NIAL/AL2O3 INTERFACIAL CHEMICAL COMPATIBILITY

beta-NiAl thin films were prepared by physical vapor deposition (PVD) either on thin PVD Al2O3 films on Si substrates or on sapphire single crystals. These samples were characterized by x-ray diffraction and electron spectroscopies [Auger electron spectroscopy and x-ray photoelectron spectroscopy (XPS)]. Crystalline films were obtained after deposition Bt room temperature. XPS depth profiles and transmission electron microscopy cross sections show that the NiAl-Al2O3 interface is sharp (1 nm) and that NiAl oxidation occurs. Ni remains chemically unaffected by the presence of oxygen while the formation of Al3+ compounds is discussed. Within the film Al and Ni appear in a single chemical environment characterized by binding energies close to those of pure intermetallic compounds. Annealing of these wafers at 600 degrees C induces surface oxidation and,particularly, the formation of an Al2O3 protective layer. (C) 1995 American Vacuum Society.