Unusual morphology of CVD diamond surfaces after RIE

Reactive ion etching of (100) CVD diamond films in O2 has been performed using a 13.56 MHz capacitively coupled reactor at pressures of 20 mTorr–100 mTorr and r.f. powers of 100 W–300 W. The formation of columnar structures was observed at the grain boundaries whereas the (100) facets were etched to yield a smooth surface under optimum conditions. For comparison, the RIE of single, isolated cubo-octahedral crystallites produced smooth (100) facets and roughened (111) surfaces reminiscent of the micro-columnar structures evident in the films.