THERMAL-PROCESS EFFECTS ON NIFE AND NIFERH FILMS

The effect of thermal processing on thin films less-than-or-similar-to 1000 angstrom of permalloy and a permalloy alloyed with Rh has been examined. Coercivity, anisotropy field, and magnetostriction were measured both before and after annealing for 30 min. The films were exposed to temperatures representative of those employed in thin-film head fabrication, 92 and 185-degrees-C anneals representing photo processes and 240-degrees-C approximating the highest temperatures used during thin-film head processing. Significant changes occurred in the thinner films after the 185 and 240-degrees-C anneals. Changes were observed in both types of films. The largest occurred in the permalloy films. The magnetostriction of both film compositions became significantly more negative after annealing at the higher temperatures, with the change in the Rh alloy films smaller. The changes in properties decreased with increasing thickness for both permalloy and the Rh alloy. Auger electron spectroscopy analysis has shown that the differences before and after annealing at the higher temperatures result from oxidation of the upper (exposed) surface of the films. These studies show that the magnetic properties, especially magnetostriction, are strong functions of the process history of permalloy thin films.