Temporary Carrier Technologies for eWLB and RDL‐First Fan‐Out Wafer‐Level Packages

Fan‐out wafer‐level packaging (FO‐WLP) process flows typically fall under two basic integration categories called chip‐first and chip‐last. In both process flows, temporary wafer carrier technologies play a crucial role. Temporary wafer bonding is classified by the mechanisms that break the temporary bond interface and their point of interaction. Depending on the integration process flows for FO‐WLP, requirements for temporary bonding differ, separating into laser‐initiated debonding of RDL‐first buildup packages, while slide‐off and lift‐off debonding is used for chip‐first packages to process molded substrates. To limit the thermal input associated with laser debonding, UV diode‐pumped solid‐state lasers are favored for the debonding step, since they provide the benefit of rapid absorption of the UV light immediately at the glass release layer interface and also allow for direct photochemical interaction at chemical bonds provided by readily available materials.