Properties of dc magnetron sputtered nickel-chromium alloy thin films

The properties of de magnetron sputtered nickel-chromium alloy thin films are examined for changes in intrinsic stress, stoichiometry and grain size as a result of heat treatment. We find that a large change in stress from compressive to tensile occurs above 300 degrees C in air ambient for films deposited under nominally low stress. Auger depth profilometry of as-deposited and heat treated films shows that a minimal change in Ni:Cr stoichiometry occurs along with a small increase in oxygen and carbon content for the heat treated film. The accompanying change in grain size of the two types of films is also examine d in addition to the large change in intrinsic stress as a function of rf substrate bias on the films during deposition. Atomic Force Microscopy of a heat treated film shows the presence of voids, which along with the increased grain size, may account for the change in film stress. It is postulated that the voids are formed by evolution of impurities.