Etch rates of CVD diamond upon irradiation by nanosecond (5-9 ns) pulses at
three different wavelengths 1078, 539 and 270 nm at laser fluences in the
range 1-1000 J/cm(2) were measured. A Nd:YAP laser system operated at first
, second and fourth harmonics was used in the ablation experiments. Both sh
allow (<15 microns) and through holes were etched in a 95-mu m thick free-s
tanding diamond film grown by microwave plasma CVD. The ablation rate was f
ound to be wavelength-independent, this result being ascribed to surface bl
ackening caused by amorphization/graphitization as confirmed by Raman analy
sis. The maximum etch rate approached 600 nm/pulse. The etch rate depended
on the crater depth, which was ascribed to the effect of laser-plasma inter
action inside the deep channel. The possibility of cutting trenches of high
aspect ratio has been demonstrated. In a separate experiment, a batch of t
hin diamond films differing in thermal conductivity (k=2-5 W/cmK) was ablat
ed with a KrF excimer laser (lambda=248 nm). No dependence of ablation rate
on film quality was observed, which could be explained assuming grain boun
daries to be the main source of thermal resistance. (C) 1998 Elsevier Scien
ce S.A. All rights reserved.