Negative bias dependence of sulfur and fluorine incorporation in diamond films etched by an SF6 plasma

Reactive ion etching of polycrystalline diamond films has been performed in an electron cyclotron resonance SF6 plasma by applying negative substrate bias (V-dc) The structure and composition at the surface were examined as a function of V-dc by scanning electron microscopy (SEM) and X-ray photoelec tron spectroscopy (XPS). The SEM images revealed that the etching proceeded almost uniformly rather than preferentially over the surface, and the morp hology after the etching was independent of V-dc The bulk plasmon loss feat ures in the C ls spectra by angle-resolved XPS revealed the evolution of an amorphous layer over a diamond film surface with increasing V-dc The resid ual sulfur and fluorine concentrations were found to be high in the interio r of the film or in the underlying diamond, ranging up to 0.6 and 1.3% for sulfur and fluorine, respectively, and rather low in the amorphous overlaye r. The depth variation of their concentrations was interpreted in terms of subsurface dynamic effects based on the incorporation and displacement of a toms by penetrating energetic ions. (C) 2001 The Electrochemical Society. A ll rights reserved.