A capacitive accelerometer using SDB-SOI structure

A capacitive accelerometer using SDB-SOI (silicon direct bonding-silicon on insulator) structure has been developed. The mass and beams of the accelerometer are fabricated with a single-crystal silicon layer 10 μm thick. The beam is formed in a spiral shape to the obtain longest beam in the minimum area. The silicon dioxide layer is etched sacrificially, which determines the capacitance gap as 1 μm. Seven kinds of accelerometers for different measurement ranges have been integrated in the same chip. The capacitance changes of the accelerometers are detected by a capacitance to voltage converter IC (TI28882D), and the output characteristics evaluated. As a result, a high sensitivity of 200 mV G−1 and wide frequency response of 200 Hz have been achieved.

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