Fine Pitch Semi-Additive RDL-Process Development

Polymer-based Redistribution Layer (RDL) interconnects are essential for advanced packaging, enabling the integration of heterogeneous systems. The increasing demand for higher component density and expanded bandwidth has driven the increase in the number of RDL layers and the reduction of their critical dimensions (CD) [1-4, 6, 7]. As the RDL pitch continues to decrease, a greater overlap in process capabilities with more costly back-end-of-line (BEOL) metallization processes is observed. In this study, we demonstrate a fully functional semi-additive RDL with a line/space of 1000 nm. With a novel adaptation to a 2 metallayer semi-additive process, we also demonstrate a fully functional 1600nm via (6400 nm via-to-via pitch) on $\text{L/S}=1600 \text{nm}$ RDL.