Equipment and Process for eWLB

During early fan‐out wafer‐level packaging (FO‐WLP), when Infineon was developing their embedded wafer‐level ball grid array technology, 200 mm physical vapor deposition (PVD) systems were used for development and initial production. The FO‐WLP PVD process flow involves the following stages: degas, pre‐clean, PVD adhesion layer deposition and copper seed layer deposition. After successful degas, the molded wafer needs to be pre‐cleaned in a plasma etch module. The pre‐clean process will involve an “over etch” to accommodate any cross‐wafer variation in the etch process. Epoxy‐molded wafers can be warped after curing, and the size and shape of the warpage hinge on the different size, density, and placement of the die. Multi‐wafer degas technology has emerged as a compelling solution to the degas throughput problem, enabling multiple wafers to be degassed in parallel before being individually transferred to subsequent process steps, without breaking vacuum.