Method for Creating Low Cost 3D MEMS Chemical Sensors by Using Through Wafer VIAS and Wafer Bonding

For some MEMS based chemical sensors, it is desirable to incorporate 3D features such as enclosed reaction chambers and both chemical & electrical I/O. Like most other MEMS devices, it is preferential to create all of these features at the wafer level. Although wafer level integration has the potential to simplify back-end & packaging requirements, improve device performance, and reduce size & cost, developing reliable processes is a significant challenge. This paper reviews our process development efforts, including some practical tips and tricks for prototyping MEMS in an R&D environment. Test devices specifically designed to assess the key processes of low cost through wafer via creation and thermocompression wafer bonding were fabricated and characterized by simple electrical and mechanical testing. Process implications are offered for both the chemical sensors of interest as well as other MEMS devices.