LASER-ASSISTED ETCHING OF DIAMONDS IN AIR AND IN LIQUID-MEDIA

Etching with the help of a copper vapor laser (wavelength of 510 nm, p ulse duration of 10 ns, pulse repetition rate of 8 kHz) of both synthe tic diamond single crystals (HPHT) and diamond polycrystalline CVD fil ms is studied in various surrounding media (air, H2O, (CH3)2SO). Diamo nd samples are virtually transparent at this wavelength, and the coupl ing of laser radiation to diamond is via the formation of a thin graph itized layer at the diamond surface. The etching rate in liquid media is slightly higher than in air at otherwise equal conditions and is as high as 50 mu m/s for etching with a scanning laser beam. Raman spect ra measurements carried out on diamond samples etched in air show the presence of glassy carbon on the surface, whereas for samples etched i n a liquid the diamond peak at 1332 cm(-1) dominates with significantl y lower intensity of the glassy carbon peak. Electroless copper deposi tion on the laser-etched features is studied to compare the catalytic activity of the diamond surface etched in air with that etched in liqu ids. Possible mechanisms responsible for the observed difference both in the structure of the etched area and in the electroless Cu depositi on onto the surface etched in various media (air or liquids) are discu ssed.