Magnetically enhanced plasma coating of nanostructures with ultrathin diamond-like carbon films

Abstract

Diamond-like carbon (DLC) films are widely used as protective coatings in a variety of technical macro- and micro-applications. However, most of the widely-used coating methods are not suitable for nanoscale applications. In this work, the method of magnetically enhanced plasma deposition (MEPCVD) was employed for the coating of AFM probes and free-standing nanostructures with 3–20 nm thick DLC films. The carbon bonding structure, mechanical and tribological properties of the films as well as the anisotropy of the coatings and its effect on the shape of nanoscale features were investigated and it is shown that the method employed produces very smooth coatings (roughness below 0.2 nm) with a significantly lower than usual internal stress of 0.5–0.8 GPa. Wear tests of AFM probes at a high load (1 μN) showed that the DLC coating decreases their wear rate by two orders of magnitude. It was found that coating of free-standing nanostructures even with ultrathin DLC films may cause their deformation due to the interface stress when the coating is asymmetric.