Hydrogen plasma etching of diamond films deposited on graphite

Poly- and nanocrystalline diamond films have been deposited using microwave plasma enhanced CVD with gas mixtures of x%CH4/15%H2/Ar (x = 0.5, 1, 3, and 5). After deposition the resulting films were exposed to a hydrogen plasma etching for 30 min. The hydrogen plasma produced preferential etching of non-diamond carbon on the surface of the samples and the development of steps and pits. Raman spectroscopy and X-ray photoelectron spectroscopy analyses on the etched films showed increased sp3/sp2 ratio and decreased surface oxygen. The etch mechanism proposed is regression of pre-existing steps and step flow.

Research highlights
► Diamond films were deposited on graphite by microwave CVD with CH4–H2–Ar mixtures.
► Hydrogen plasma etching resulted in preferential etching of non-diamond carbon.
► After etching, the surface of the samples developed steps and pits.