| dc.description.abstract | Micro-precision machining of sapphire has always been challenging because of its hard-ness, brittleness, wear resistance, and high transmission. Ultrashort-pulsed lasers are considered to be one of the most promising tools. In this study, a new laser sapphire drilling strategy was developed to reduce the taper of micro-drilling. The carrier is a sapphire substrate with a thick-ness of 200 microns, and the laser is a femtosecond laser with a pulse duration of 300 femto-seconds and a wavelength of 1030 nanometers. This scanning strategy adopts a double-cycle auger method with inner and outer double loops: Cycle I uses a relatively low laser energy intensity, first conducts the outer loop auger with a larger diameter, and then implements a smaller diameter auger. Inner loop auger; while Cycle II increases the energy intensity, repeat-ing the outer and inner double loop auger of Cycle I. The experimental results show that after one cycle of auger drilling, an hourglass-like hole will be formed in the substrate due to the complex interactions between light and material in the ablation process. The hole’s final struc-ture and shape are determined by the overall effects of light-sapphire interactions and the com-plex processes of the ablation and the deposits from the cooling and resolidification processes. The second cycle of the auger effectively removes these deposits, effectually reducing the taper of the round hole. Finally, this study used a mixed solution of sulfuric acid and phosphoric acid to further etch away the damage and stucuturelly altered layers around the hole wall. As a result, this study successfully realized through holes with a diameter of 105 μm, a taper angle of 0.5, and with an aspect ratio of 1.6. | en_US |