Etching of nondiamond carbon in diamond thin films synthesized by hot-filament chemical vapor deposition with ultraviolet irradiation

The etching of nondiamond carbon present in diamond thin films which were grown using the CVD method has been studied with UV irradiation in air. The etching of nondiamond carbon was accelerated by UV irradiation, and hence the temperature required was lowered from 600 degrees C to 250 degrees C. On the other hand, the temperature required to etch diamond in the film did not change even with UV irradiation. Selective etching of nondiamond carbon in diamond thin films can be achieved at temperatures between 250 degrees C and 550 degrees C. These etching effects are caused by excited atomic oxygen produced by the UV irradiation and not by the direct excitation of the film by UV irradiation.