A monolithic 3D fully-differential CMOS accelerometer

This study presents a novel inertia sensor design to monolithic integrate x, y, and z-axis accelerometers on a single chip. The chip is implemented using the TSMC 0.35μm 2P4M CMOS process, and post metal wet-etching and dielectric dry-etching processes. Thus, the fully-differential capacitance sensing in-plane and out-plane CMOS accelerometers are realized. The measurement results demonstrate the sensitivities for in-plane and out-of-plane accelerometers are 3.9mV/G and 0.9mV/G, respectively. The coupling ratios for in-plane and out-plane accelerometer are 3∼5% and 15∼30%, respectively.