Abstract: A pressure sensor fabricated onto a substrate using conventional CMOS fabrication processes. The pressure sensor is built on a substrate having a first conductivity type and has defined in it a well of an opposite conductivity type. This well defines a membrane. Resistors are diffused into the well. Source/drain regions are provided for leadouts for the resistors. An n-cap is provided for the resistors. Metalization contacts may be provided to connect the membrane to a positive bias during a membrane etching process. A cavity is provided on the underside of the substrate through which pressure is applied to the membrane. Signal conditioning circuitry, such as an operational amplifier, may also be fabricated on the same substrate preferably using the same IC processes.

Abstract: A novel process for fabricating an integrated circuit sensor/actuator is described. Silicon islands are created by forming deep trenches in a substrate and lining the trenches with oxide. This forms silicon islands substantially surrounded by electrically isolating oxide. The anchor portion of the sensor/actuator beams is connected to the islands and is released from the substrate and therefore is also electrically isolated from the substrate. The IC sensor/actuator is manufactured by forming deep trenches in a substrate.