因為堅硬、易脆耐磨耗與高透光等特性，藍寶石的微精密加工一直很具有挑戰 性，超快脈衝式雷射被認為是很有潛力的工具之一。 本研 究以降低雷射藍寶石基板微 鑽孔之錐度為目的，嘗試一新雷射加工策略。載 板為厚度 170微米的藍寶石基板， 雷射則使用 300飛秒脈衝期、波長 1030奈米的飛秒雷射。此策略採用一雙週期、內外 雙迴圈之螺旋鑽法 ：週期 一使用相對較低的雷射能量強度 (Energy intensity)，先進行直 徑較大之外迴圈螺旋鑽，再實施直小的內；而週期 二，則提高能量強 度，重複週期 一之外、內雙迴圈螺旋鑽。實驗結果顯示，經過週期 一之螺旋鑽後，會 因為燒蝕過程複雜的光與材料相互作用，在基板內形成 似沙漏形狀之孔洞 ，孔壁週圍 材料結構與最後形狀，則由燒蝕過程複雜的光相互作用、在不同階段所成包括融化、再凝固之重鑄層與堆積殘渣。週期 二螺旋鑽可有效移除這些沉積物， 有效地降低圓孔錐度。最後，本研究使用 硫酸與磷混合溶液 ，以進一步改因雷射 能量在孔壁週圍引起的材質改變。藉此，本研究成功地實現徑 105 μm、錐角 0.5°、深寬比為 1.6之通孔;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.
