A MEMS inertia sensor with Brownian noise of below 50 nG/√Hz by multi-layer metal technology

This paper reports a highly-sensitive MEMS accelerometer with the thermal-mechanical noise (Bn) of below 50 nG/√Hz (G = 9.8 m/s2) within the footprint of 4×4 mm2. Regarding to the suppression of Bn, we have investigated the relationship between the Bn and the thickness of the proof mass; to downscale the proof mass, we have proposed a multi-layer metal proof-mass structure made of electroplated gold. The actual Bn of the proof mass was experimentally evaluated to be 22 nG/√Hz. The measurement results suggest that the proposed device has potential of sub-1mG sensing.