Patent ID: 7373833

Claim:
A pressure sensing system formed in a monolithic semiconductor substrate, the pressure sensing system comprising: (a) driver circuitry formed in the monolithic semiconductor substrate, the driver circuitry being responsive to input electrical signals for generating an output pressure signal: (b) a capacitive pressure sensing device formed on the semiconductor substrate, the capacitive pressure sensing device including (i) a conductive lower capacitor plate formed at an upper surface of the semiconductor substrate; (ii) a conductive pad formed at the upper surface of the semiconductor substrate and spaced-apart from the lower capacitor plate; (iii) patterned dielectric material formed over the upper surface of the semiconductor substrate and having a first opening formed therein to expose an upper surface of the conductive pad and having a second opening formed therein over the lower capacitor plate; (iv) a supporting layer of dielectric material formed on the patterned dielectric material, the supporting layer having a first opening formed therein over the conductive pad and having a plurality of openings formed therein over the second opening in the patterned dielectric material; and (v) an upper layer of conductive material formed on the supporting layer and extending through the first opening in the supporting layer and into the first opening in the patterned dielectric material to form electrical contact with the exposed upper surface of the conductive pad, the upper layer of conductive material extending over the plurality of openings formed in the supporting layer to close said openings to define an enclosed cavity between the lower capacitor plate and the upper conductive layer; and (c) a conductive interconnect structure formed in the monolithic semiconductor substrate, the conductive interconnect structure being connected between the capacitive pressure sensing device and the driver circuitry for providing electrical pressure signals developed by the capacitive pressure sensing device as input electrical signals to the driver circuitry.