Magnetic properties of NiFe sputtered on sloping surfaces

RF diode sputtered NiFe films deposited on tilted surfaces can exhibit a 90° rotation of the magnetic easy axis from the direction of applied magnetic field. The rotation is largely independent of the sign of the magnetostriction, indicating a shape anisotropy originating with film crystallite morphology. It is less prevalent with increasing substrate bias. At low powers a large magnetic anisotropy is observed perpendicular to the plane defined by the tilted surface normal and the substrate holder normal. It is important for the function of thin film heads that films deposited on slanted surfaces have good magnetic properties, particularly near the apex region of inductive film heads. Evaporation experiments have shown that the magnetic properties of thin NiFe films depend critically on deposition angle-of-incidence. The situation for sputtered films is more complex since the source is large and close to the substrate being coated. However, even for sputtering when the surface being coated is tilted with respect to the substrate holder and target surfaces, material will impinge asymmetrically with respect to the slanted surface normal, so some sort of averaged angle-of-incidence effect can be expected