FEN PHASE GENERATION EFFECTS FOR HIGH MOMENT FETAN FILMS

FeN phase generation has been observed by x-ray analysis in FeTaN films, which normally show alpha-Fe, TaN phase, and no FeN phases. With a rise in substrate temperature T(s) above 200-degrees-C, FeN phases are generated in nitrogen reactive sputtering process with columnar structure formation, and remain after annealing. With FeN phase generation, coercivity H(c) and magnetostriction lambda values increase markedly. Moreover, internal stress sigma for the films increases drastically. The FeTaN films, sputtered on low temperature substrate, generate no FeN phases, and show low H(c), about 0.1 Oe, and low lambda. Consequently, FeN phase generation with columnar structure formation has negative effects for FeTaN films to be used as magnetic head core materials. For preparation of FeTaN films, the substrate temperature has to be controlled to a sufficiently low value for suppression of FeN phase generation.