A MEMS Microphone in a FOWLP

This work presents a fully functional miniaturized MEMS microphone demonstrator assembled within a modified Fan Out Wafer Level Package (FOWLP) process chain. Core of the development is the adaption of the FOWLP-process to MEMS-microphones, which have not yet been fully processed in the wafer fab. Instead, these microphone chips contain non-released membranes making them sufficiently robust to withstand backend processes, such as laminating and molding. The membrane release itself is performed on the reconstituted mold-wafer and postponed to a later process step. Mechanical stress effects induced by the package onto the MEMS are limited to a minimum by the implementation of stress decoupling suspension structures on the MEMS die.