Surface Structuring of Diamond-Like Carbon Films by Chemical Etching of Zinc Inclusions

A diamond-like carbon (DLC) film with a nanostructured surface can be produced in a two-step process. At first, a metal-containing DLC film is deposited. Here, the combination of plasma source ion implantation using a hydrocarbon gas and magnetron sputtering of a zinc target was used. Next, the metal particles within the surface are dissolved by an etchant (HNO₃:H₂O solution in this case). Since Zn particles in the surface of Zn-DLC films have a diameter of 100–200 nm, the resulting surface structures possess the same dimensions, thus covering a range that is accessible neither by mask deposition techniques nor by etching of other metal-containing DLC films, such as Cu-DLC. The surface morphology of the etched Zn-DLC films depends on the initial metal content of the film. With a low zinc concentration of about 10 at.%, separate holes are produced within the surface. Higher zinc concentrations (40 at.% or above) lead to a surface with an intrinsic roughness.