Novel approach to nanosecond laser drilling of a crack-free through hole on SiC wafer
Luis Bustamante, Dileep Karnam, Yu‐Lung Lo
Abstract
Our study focuses on the precision and efficiency of nanosecond laser drilling in silicon carbide (SiC) wafers, particularly for applications in electronics and advanced manufacturing . Nanosecond laser drilling is increasingly preferred due to its ability to minimize thermal damage and ensure crack-free edges, making it an ideal choice for high-precision machining. We investigate the effects of infrared nanosecond lasers on SiC wafers through percussion drilling without a protective layer, employing three different mechanisms: 3-step, 2-step, and 1-step methods, using a laser beam size of 15 μm. The experimental results show that the top diameters of the drilled holes were 23.25 μm, 20.66 μm, and 24.35 μm, while the bottom diameters measured 14.76 μm, 15.13 μm, and 13.28 μm, respectively. Additionally, the study explores the material removal mechanism and the thermal explosion model to enhance surface quality. Our findings indicate that all these laser drilling methods produce crack-free holes, with the 2-step mechanism achieving the highest aspect ratio of 17.10. The top and bottom sections of the holes exhibited low surface roughness values of 495 nm and 611 nm, respectively. These results demonstrate the capability of nanosecond laser drilling to achieve high aspect ratios, reduce the heat-affected zone (HAZ), and enhance the surface quality of the drilled holes. This method proves effective in minimizing surface defects and improving machining precision. Understanding the role of multiphoton absorption and defect-induced absorption further refines the optimization of laser parameters for achieving precise and controlled material ablation.