Thermal stability studies on ion beam sputter deposited substoichiometric iron nitride thin films

Iron nitride films were deposited on Ge(100) wafers by a reactive ion beam sputter deposition of iron in an ammonia atmosphere. The composition and microstructure of these films were monitored by Rutherford backscattering spectroscopy analyses and X-ray diffraction experiments. The influence of ammonia partial pressure on the microstructure of the films was studied. It was found that the optimum ammonia pressure for the alpha ''-Fe16N2 phase formation was about 5 x 10(-4) Torr or a little higher. The thermal stability of these Fe-N films was also investigated. Upon annealing at a temperature below 180 degrees C in a flowing nitrogen atmosphere, the alpha '' phase would decompose and nitrogen atoms would be released from the films.