Single-Wafer Pressure Capacitive Sensor

A novel manufacturing process for pressure sensor without the need of wafer bonding is presented. Its main advantages are a simple fabrication process and an efficient integr ability with other devices. The sensor is composed of a polysilicon membrane that deflects due to the 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 nonlinear region. Among the most significant features of this device are versatility, high reliability, integrability and high sensivity.