Oxidation behavior of AlN films at high temperature under controlled atmosphere

摘要

Oxidation behavior of AlN films deposited on Si substrates by unbalanced magnetron sputtering was investigated over temperatures of 700-1200 deg C in different atmospheres by analyzing changes in appearance and crystalline phases, as well as microstructures. The atmospheres contained air, nitrogen, and forming gas (N_2/H_2 = 9), which exhibited drastically different nitrogen/oxygen partial pressure ratios. Observed color changes in appearance were associated with oxidation of the nitride film, which was analyzed by exploring Gibbs free-energy changes at various temperatures and nitrogen/oxygen partial pressures. Different phases of oxidants including intermediate delta-Al_2O_3 and thermodynamically stable alpha-Al_2O_3 were discerned by X-ray diffraction. Oxidation of A1N and phase transformation in Al_2O_3 depended on not only the temperature but the nitrogen/oxygen partial pressures. Microstructures of both oxide phases could be resolved by micro-Raman spectroscopy.