Surface Planarization of Polymeric Interlayer Dielectrics for FOWLP Applications

The surface planarity of polymeric interlayer dielectrics becomes a key factor for the multi-level interconnection for fan-out wafer level package. The surface topography of polymeric interlayer dielectrics depends on the underlying metal patterns, and the higher degree of planarization was observed with narrower line and larger space. The pressing method is proposed to flatten the surface undulations. The surface of PBO was pressed with a pressing plate during the soft-bake process, and the surface planarity was observed to be improved effectively.