The characteristics of femtosecond laser ablation of AlN and Al<sub>2</sub>O<sub>3 </sub>for precision microfabrication are studied
experimentally. Specifically, the process characteristics during femtosecond laser drilling of microholes with sub-100
μm diameter are investigated for varying laser parameters and beam path designs for trepanning. The accumulation of
sub-micrometer size particles within the hole is prevented using a blower and vent system. Through process optimization
the microdrilling with good hole quality is achieved.