Patent ID: 7448277

Claim:
A method of forming a capacitive pressure sensor having a mechanical capacitor comprising a fixed electrode and a moving electrode defined by a conductive plate, the method comprising: forming a diaphragm on a surface of a first wafer containing at least a first conductive layer; forming the conductive plate on the first wafer so as to be mechanically coupled but electrically insulated from the diaphragm; depositing a sacrificial layer over the conductive plate; depositing a conductive layer on the sacrificial layer to define the fixed electrode spaced apart from the conductive plate; removing the sacrificial layer to yield a sensor structure on the first wafer, the sensor structure comprising the diaphragm and the mechanical capacitor comprising the conductive plate and the fixed electrode; bonding the first wafer to a second wafer that carries interface circuitry for the sensor, the sensor structure facing the second wafer and the mechanical capacitor thereof being electrically connected to the interface circuitry as a result of the bonding step; and then etching at least a portion of the first wafer to release the diaphragm and form an opening that exposes the diaphragm to an environment in which pressure changes therein cause the diaphragm to deflect and, as a result of the mechanical coupling between the diaphragm and the conductive plate, cause the conductive plate to move relative to the fixed electrode.