Reaction of thin metal films with crystalline and amorphous Al₂O₃

Abstract

We have investigated the thermal reaction between thin transition metal films and sapphire, alumina or amorphous Al2O3 using backscattering spectrometry and x-ray diffraction. Thin films of Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Pt were deposited on the substrates by rf sputtering in an Ar gas ambient. The samples were subsequently annealed in vacuum at 800–900 °C for 20 min to 4 h duration. We found that only films of Y, Ti, and Hf react, regardless of the type of substrate, by forming aluminides near the substrate and oxides on the surface. The other metal films do not react with the Al2O3 substrates. Our results agree with thermodynamic consideration based on the heats of reactions between metals and Al2O3.