Surface anisotropy of CrxN1−x films prepared on an inner wall by magnetic sputtering

The Cr_xN_1−x films were prepared by magnetic sputtering on an inner wall of a column. Their surface morphologies were studied by atomic force microscopy (AFM) and found to be anisotropic. The 3-D AFM images indicate the grains grow upward along the rotational axis of the system. The AFM top views show a mosaic-like pattern for all samples. Analysis of the height-height correlation function demonstrates that correlation length along the rotational axis of the system is longer than that vertical to the axis. The correlation length and RMS roughness increase with the flow rate of N₂. A deposition model proposed that the shadowing effect of the reactive gas N₂ is the dominant factor for surface anisotropy. The bias added on the substrate is regarded to modulate the grain direction to the rotation axis and enhance roughness and defects.