Fabrication of High-Aspect-Ratio Microstructures Using Excimer Lasers

An excimer laser micromachining system is developed to study the process in fabricating high-aspect-ratio microstructures. Specifically, the study experimentally examines process efficiency and the impact of changing major laser operating parameters on the resulting microstructural shapes and morphology. The materials considered in the study include glass, silicon, and aluminum. The ablation or micromachining rate has been observed to be strongly dependent on the operating parameters, such as the pulse fluence, number, and repetition rate. The results specifically indicate that ablation at low fluence and high repetition rate tends to form a V-shaped cavity, while a U-shaped cavity can be obtained at high fluence and low repetition rate. Additionally, the present study also indicates that a three-dimensional V-shaped cavity with large vertex angle can be formed by varying the focus depth of excimer laser. Materials of low thermal conductivity and low melting temperature are indeed more applicable to laser ablation.