CMOS integrated microsensor with a precision measurement circuit

US5659195A · kind A · utility

Assignee

• The Regents of the University of California · US

Inventors

• William J. Kaiser · Los Angeles, US
• Kristofer S. J. Pister · Orinda, US
• Oscar M. Stafsudd · Los Angeles, US
• Phyllis R. Nelson · Yreka, US
• Amit Burstein · West Hollywood, US

Key dates

• Filing date: Jun 8, 1995
• Grant date: Aug 19, 1997
• Expiry date: Jun 8, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G01P2015/0831
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

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 t…