Laser-assisted etching of diamonds in air and in liquid media

Etching with the help of a copper vapor laser (wavelength of 510 nm, pulse duration of 10 ns, pulse repetition rate of 8 kHz) of both synthetic diamond single crystals (HPHT) and diamond polycrystalline CVD films is studied in various surrounding media (air, H2O, (CH3)2SO). Diamond samples are virtually transparent at this wavelength, and the coupling of laser radiation to diamond is via the formation of a thin graphitized 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 spectra measurements carried out on diamond samples etched in air show the presence of glassy carbon on the surface, whereas for samples etched in a liquid the diamond peak at 1332 cm(-1) dominates with significantly lower intensity of the glassy carbon peak. Electroless copper deposition on the laser-etched features is studied to compare the catalytic activity of the diamond surface etched in air with that etched in liquids. Possible mechanisms responsible for the observed difference both in the structure of the etched area and in the electroless Cu deposition onto the surface etched in various media (air or liquids) are discussed.