Anomalous Grain Growth in Sputtered CoCrMn Thin Films

Abstract

This paper presents anomalous grain growth in sputtered hcp CoCrMn thin films: The grain size is about 250 nm wide and a few micrometers long in the film of only 50 nm thickness. Both selected area diffraction (SAD) and x-ray texture analysis indicate that the perpendicular direction to the substrate is parallel to the zone axis of hcp<100> and hcp<110>. SAD also indicates that short axis of elongated grains is the c-axis of hcp structure, i.e. grains are elongated in the orthogonal direction to the c-axis. In addition, these elongated grains compose a grain bunch, in which grains are parallel to each other. Phi (φ) scan at grazing incidence x-ray diffraction (GID) geometry reveals that bunches are, as a whole, randomly oriented. However, neighboring bunches are misoriented about 10-20 degrees with each other, which is consistent with TEM observation. Such an anomalous grain growth of CoCrMn thin film is explained in views of mechanisms of nucleation and surface energy minimization.