Lateral capacitive CMOS accelerometer with structural curl compensation

We present successful experimental results from the first lateral capacitive accelerometer to be designed and manufactured in a conventional CMOS process. Compatibility with conventional CMOS provides advantages of low cost, high yield and fast prototyping that should be transferable to any CMOS foundry. A fully differential capacitive-bridge interface which can not be realized in polysilicon technology is designed and implemented. Out-of-plane curling associated with the composite structural layers is compensated to first order through a curl matching technique. The prototype accelerometer has a measured sensitivity of 1.2 mV/g and a 0.5 mg/rtHz noise floor at the output of the sensing element.