LOW-ENERGY ION-INDUCED DAMAGE OF POLYCRYSTALLINE DIAMOND FILMS

Polycrystalline films with different diamond qualities, prepared by microwave chemical vapour deposition (MWCVD) and hollow cathode arc plasma CVD, were post-treated by normal neon ion bombardment at low energies (100-1600 eV). The bombardment caused various ion-solid interactions, resulting in erosion and modification of the diamond surface. In addition, the estimation of the etching rates and, consequently, the sputtering yields, topography and structure modification were studied using scanning electron microscopy and Raman spectroscopy respectively. More details of the ion bombardment effects on the films should be investigated by cross-sectional transmission electron microscopy in connection with electron energy loss spectroscopy at the C K edge. The experimental results show ion-energy- and film-quality-dependent etching effects-up to threshold energies-for surface topography modification. Two different algorithms were used to approximate the ion-induced damage depths in polycrystalline diamond from about 10 angstrom (100 eV) up to about 70 angstrom (1600 eV), which are important for layer application. The results are discussed in the light of a two-step process caused by ion bombardment.