Film structure and magnetic properties for Co-Cr sputtered films

Film structure for Co-Cr sputtered film was observed using a scanning electron microscope (SEM) and transmission electron microscope (TEM) and was related to magnetic properties and sputtering parameters. The cross-sectional view seen by a SEM, which provides us with topographical information, was strongly dependent on the sputtering parameter, Ar pressure in particular. Columnar structure in the SEM view was observed only in films deposited under high Ar pressure. Film deposited under low Ar pressure exhibited no structure in its fracture cross section, namely, flat fracture plane. A TEM, which provides us with crystallographical information, revealed that all films in the present investigation have almost the same crystallographical structure, which consists of fine columnar grains. Columnar structure viewed by a SEM is accompanied by poor c-axis orientation and gives evidence of intergranular fracture and low tensile strength for Co-Cr films. Perpendicular coercive force and anisotropy field decreased abruptly above the Ar pressure at which columnar structure could be observed in the cross-sectional SEM view.