Ultraviolet Laser Diode Ablation Process for CMOS 45 nm Copper Low-K Semiconductor Wafer

This paper presents the optimization work of 355 nm ultraviolet (UV) laser diode ablation process for CMOS 45 nm Copper (Cu) low-k semiconductor wafer. The micromachining parameters included laser power, laser frequency, feed speed, and defocus amount were optimized via design of experiment (DOE). Package reliability stressing tests were carried out as part of the efforts to validate the robustness. The results show that high repetition rate, low laser pulse energy and a high pulse overlap produced zero dicing defects. The laser groove depth increased as the laser pulse energy increased. It is shown that, laser grooving is one of the best solutions to choose for dicing quality, throughput and yield improvements for CMOS 45 nm Cu low-k wafer dicing.