Anisotropic etching of a fine column on a single crystal diamond

We have fabricated very sharp tips, without slight slopes around their bases, on single crystal diamond for a field emitter by reactive ion etching (RIE) and a microwave plasma etching (MWPE) technique in CO2 and H-2 gas. After a fine column was fabricated on a diamond surface by a RIE, it was reformed into a sharp tip by MWPE. It was found that WMPE in CO2 and H-2 gas was an anisotropic etching for a fine column on diamond. When the CO2/H-2 ratio was less than 0.5%, the effect of etching was smaller. When the CO2/H-2 ratio was more than 5%, the etch pit of the diamond surface was larger and deeper. As the etching time increased, the etch pit and surface roughness also increased. The optimum conditions were as follows: CO2/H-2 = 0.5% and etching time of 1-4 h. We have also accomplished the fabrication of slender sharp tips from a tall column by this technique. This is the first report on slender sharp tips of diamond fabricated under controlled conditions. (C) 2001 Elsevier Science B.V. All rights reserved.