Fine Trench Fabrication by Excimer Laser Ablation and Plasma Etching

In this paper, we propose a new fabrication method of fine trenches in organic RDL interposer and package substrates, using excimer laser ablation and plasma etching technology. The method focuses on dual-damascene process, rather than SAP which uses photo lithography process to fabricate traces.Excimer laser ablation is suitable for fine patterning in organic material, however 2.0 µm line and space patterns in polyimide were deformed in our investigation. Our proposal is an innovative method to minimize the deformation by process integration with plasma etching. We performed another investigation to deposit metal layer on polyimide and pattern the metal layer by excimer laser, then etch by RIE. Approximately 1.5 µm line and space patterns with high aspect ratio of 5.0 was successfully fabricated. The integration of excimer laser ablation and RIE is effective approach to process fine trench pattering of organic RDL and package substrates by dual-damascene process.