Changes in structure and magnetic properties of Co-Cr films by oblique incident of sputtered particles

The effect of the incident angle of sputtered particles relative to the substrate surface on the magnetic properties and c-axis orientation of Co-Cr films has been investigated using an opposed-targets sputtering apparatus that can operate at a gas pressure as low as 1×10^-4 Torr. The c-axis orientation and magnetic properties of the film depend little on the incident angle below 45°. However, oblique incidence at an angle above 50° leads not only to a significant deterioration of the c-axis orientation but also to a marked decrease in the mean crystallite size, saturation magnetization, and perpendicular magnetic anisotropy energy. Films deposited at large incident angle have a porous structure and large c-axis canting angle. This is caused by the shadowing effect due to the surface roughness of the substrate. Substrate temperature and ion bombardment of the substrate during sputtering also affect the magnetic properties and c-axis orientation of the film but do not improve them significantly