A SCR-based ESD protection for MEMS — Merits and challenges

A silicon-controlled rectifier (SCR) is presented as an ESD protection device for microelectromechanical systems (MEMS) in a MEMS-on-CMOS process flow. Measurements on SiGe MEMS devices have been performed and the SCR is shown to provide the Class0 MEMS with protection levels up to 5.5kV HBM. The effect of the MEMS capacitance on the SCR robustness during ESD is investigated. Through simulations and measurements, the scope of the proposed ESD protection scheme has been evaluated. Current overshoots caused by large MEMS capacitances (>;100pF) are shown to be a potential issue in the SCR operation.