A high sensitivity capacitive microaccelerometer with a folded-electrode structure

A high sensitivity capacitive silicon accelerometer with a new device structure is presented. The structure uses a fixed rigid electrode suspended between a proof mass and a stiff moving electrode to provide differential capacitance measurement and force-rebalancing. High sensitivity is achieved by forming a thick silicon proof mass and a narrow uniform air gap over a large area. The mechanical noise floor is reduced by incorporating damping holes in the electrodes. The measured sensitivity for a device with 2.6 mm/spl times/1 mm proof mass and 1.4 /spl mu/m air gap is /spl ap/100 pF/g. The calculated mechanical noise floor for the same device is 0.18 /spl mu///spl radic/Hz at atmosphere.