With the latest fan-out packages targeting high bandwidth applications, RDL line/space geometries are rapidly moving towards sub-micron dimensions. With smaller dimensions, reducing Rc becomes more critical, and challenges in reliability and yield of the various wafer processing technologies becomes a key factor in fan-out’s continuing adoption for these demanding applications.
This presentation will discuss solutions for optimizing yield and productivity during physical vapor deposition (PVD) of under-bump and redistribution metal layers. The challenges in PVD processing of FOWLP are varied, such as contamination, particles and wafer warpage. The latest PVD hardware specifically designed for BEOL processing has all the necessary features a UBM/RDL customer requires for this application, such as in-situ co-pasting hardware designed to increase uptime, and multi-wafer degas technology to significantly improve wafer throughput and lower Rc.