Excimer Laser Ablation for the Patterning of Ultra‐fine Routings

Excimer laser ablation is introduced as a direct patterning process that uses proven industrialized excimer laser sources emitting high‐energy pulses at short wavelengths to remove polymer materials with high precision and high throughput. This chapter reviews the status of advanced packages and details an innovative and alternative patterning process. This new patterning solution uses excimer laser ablation to integrate via and RDL traces in one patterning process step, followed by seed layer deposition, plating, and planarization steps. Advanced packaging approaches including chip‐on‐chip stacking, high density fan‐out wafer‐level packages, and embedded ICs will need thinner substrates, redistribution layers, and other interconnects with finer traces and higher resolution vias. In the excimer laser ablation process, patterning after curing provides complete pattern integrity of the structure profile as compared with structures made using photolithography process. The chapter also presents the advantages of excimer laser enabled dual damascene RDL.