초록 ▼

Improved microsensors are provided by combining surface micromachined substrates, including integrated CMOS circuitry, together with bulk micromachined wafer bonded substrates which include at least part of a microelectromechanical sensing element. In the case of an accelerometer, the proof mass is

Improved microsensors are provided by combining surface micromachined substrates, including integrated CMOS circuitry, together with bulk micromachined wafer bonded substrates which include at least part of a microelectromechanical sensing element. In the case of an accelerometer, the proof mass is included within the wafer bonded bulk machined substrate, which is bonded to the CMOS surface machine substrate, which has corresponding etch pits defined therein over which the wafer bonded substrate is disposed, and in the case of accelerometer, the proof mass or thin film membranes in the case of other types of detectors such as acoustical detectors or infrared detectors. A differential sensor electrode is suspended over the etch pits so that the parasitic capacitance of the substrate is removed from the capacitance sensor, or in the case of a infrared sensor, to provide a low thermal conductance cavity under the pyroelectric refractory thin film. Where a membrane suspended electrode is utilized over an etch pit, one or more apertures are defined therethrough to avoid squeeze film damping. Accelerometers built according to the methodology are provided with a nulling feedback voltage to maintain the switch DC voltage across sensing capacitors in a null condition and to maintain high sensitivity without requiring either a precision transformer or regulated power sources in the capacitance bridge of the accelerometer.

대표청구항 ▼

A CMOS integrated microsensor comprising: a first semiconductor substrate having surface machined therein an etch pit; a CMOS circuit fabricated within said first substrate; and a semiconductor, wafer-bonded second substrate disposed on said first substrate over said etch pit, said wafer bonded seco

A CMOS integrated microsensor comprising: a first semiconductor substrate having surface machined therein an etch pit; a CMOS circuit fabricated within said first substrate; and a semiconductor, wafer-bonded second substrate disposed on said first substrate over said etch pit, said wafer bonded second substrate being bulk micromachined from said first substrate to define bulk-micromachined structures therein, including at least a portion of a sensor element within said second substrate disposed opposite said etch pit in said first semiconductor substrate, said CMOS circuit being fabricated within said first substrate separately from said bulk-micromachined structures in said second substrate, said second substrate being bonded to said first substrate at temperatures below that which would affect said CMOS circuit fabricated in said first substrate, whereby said microsensor is fabricated with said CMOS circuit and combined with microelectromechanical structures as fabricated by bulk machined processes.