Abstract: A micromechanical sensor is fabricated on a semiconductor wafer, and a control circuit is fabricated on another semiconductor wafer. A cavity is etched on the back side of the control circuit wafer, the cavity being formed such that the sensor on the other wafer fits within the cavity when the wafers are brought together in an adjoining relationship. Through-holes are etched through the back side of the control circuit wafer to allow access to electrical contact points, and a patterned layer of metal is deposited to form electrical interconnections between the electrical contact points and termination points on the back side of the wafer via the through-holes. The termination points are arranged such that electrical contacts of the sensor contact the termination points when the wafers are placed in the adjoining relationship. The wafers are then cleaned and bonded together in the adjoining relationship.

Abstract: An electrostatically actuated micromechanical sensor having a guard band electrode for reducing the effect of transients associated with a dielectric substrate of the sensor. A proof mass, responsive to an input, is suspended over the substrate and one or more electrodes are disposed on the substrate in electrostatic communication with the proof mass to sense the input acceleration and/or to torque the proof mass back to a null position. A guard band electrode is disposed over the dielectric substrate in overlapping relationship with the electrodes and maintains the surface of the substrate at a reference potential, thereby shielding the proof mass from transients and enhancing the accuracy of the sensor. A dissolved wafer process for fabricating the micromechanical sensor is described in which the proof mass is defined by a boron doping step. An alternative fabrication technique is also described in which the proof mass is defined by an epitaxial layer.