A STUDY OF THE PHYSICAL-PROPERTIES AND ELECTROCHEMICAL-BEHAVIOR OF ALUMINUM NITRIDE FILMS

films of aluminium nitride (AlN) were deposited onto glass substrates by reactive sputtering. Various N-2 partial pressures were used to pro duce films the composition of which ranged from pure aluminium to stoi chiometric aluminium nitride. X-ray diffractometry, electrical resista nce measurements and electrochemical tests were carried out to charact erize these films. The XRD patterns show that the films are stoichiome tric (N/Al = 1) for a nitrogen partial pressure P-N2 = 1.33 x 10(-2) P a. From XRD patterns and electrical resistance values of the films, we have demonstrated that for under-stoichiometric films P-N2 < 1.33 x 1 0(-2) Pa, N/Al < 1)), the structure goes through an intermediary state where both metallic (Al) and ceramic (AlN) phases rake place. The ele ctrochemical behaviour of the films was studied in H2SO4 and HCl solut ions using classical electrochemical techniques as impedance diagrams and polarization curves. The results allow the proposition of a model for the under-stoichiometric films, which describes a contact between the metallic phase of Al and ceramic phases of AlN. When N-2 partial P ressure is increased, the corrosion resistance of the films is also in creased. The stoichiometric AlN films P-N2 = 1.33 x 10(-2) Pa)) show a corrosion resistance superior by several orders of magnitude to those of the under stoichiometric ones. (C) 1997 Elsevier Science S.A.