Capacitive Pressure Sensor and Characterization as RF MEMS Device

In this paper, a MEMS capacitive pressure sensor, fabricated using a novel manufacturing process without the need of wafer bonding, is presented. The sensor is composed of a polysilicon membrane that deflects due to pressure difference applied over it. Two operation regions are observed: a non-linear sensitivity region at low pressure (0-30 kPa) and a linear one (30-200 kPa) in touch mode. A capacitance-to-frequency conversion circuitry is designed and validated to provide a sensitive sensing module. Experimental results show a sensitivity of 28.7 fF/kPa and of 13.93 Hz/kPa in the non-linear region. Finally, the microsensor is characterized as a RF MEMS tunable capacitor, in order to be used in radiofrequency applications, and parameters such as tuning ratio and quality factor are obtained. Among the most significant features of this device are versatility, high reliability, integrability, and high sensitivity.