Growth rate dependence of nitrogen incorporation in reactively sputtered FeXN films for recording head poles

In this paper we show that the efficiency of nitrogen incorporation in reactively sputtered FeAlN and FeN films is strongly dependent on the growth rate of the films. Efficiency is defined as the amount of nitrogen incorporated for a given ratio of arriving iron atoms to arriving nitrogen atoms. These findings are in contrast to previous work, which has suggested the amount of nitrogen incorporated in the films should be determined by this arrival flux ratio alone, and independent of growth rate. This difference may be due to the larger range of deposition rates explored in this work. A simple and phenomenological kinetic model of the deposition process is used to rationalize the observed behavior. This behavior has important consequences for scaling the deposition of FeXN up to commercial deposition rates while maintaining soft magnetic properties. This is because the amount of nitrogen incorporated has a strong effect on the soft properties of these pole materials.