Thin film encapsulated SiGe accelerometer for MEMS above IC integration

This paper presents the design, fabrication and characterization of a thin film encapsulated SiGe accelerometer, in an attempt to demonstrate the feasibility of fabricating SiGe MEMS inertial sensors above standard CMOS with thin film wafer level permanent packaging. The capacitive in-plane inertial sensor features comb fingers and shock stoppers with minimum lateral gap of 500nm. The thickness of the structural layer is 4μm, which is processed on a wafer with silicon oxide protected metal layer, to mimic the top metal of standard CMOS. Both dynamic and angular electrical characterizations of the sensor are performed. The performance of the senor has been compared with commercialized accelerometer.