Single-layer silicon-on-insulator MEMS gyroscope for wide dynamic range and harsh environment applications

The Army Aviation and Missile Command (AMCOM), Morgan Research Corporation, and Aegis Research Corporation are developing an SOI-based vibratory-rate z-axis MEMS gyroscope utilizing force-feedback control, and intended for wide dynamic range and harsh environment applications. Rate sensing in small diameter ballistic missile guidance units requires a rate resolution of less than 1 degree(s)/hr over a range of -3000 to +3000 degree(s)/sec, resulting in a dynamic range of 107. In addition, the devices must operate through military specifications on temperature (-55 degree(s)C to +125 degree(s)C) and vibration (1000 g at 5 - 15 kHz). This paper presents modeling, simulation, and fabrication efforts, as well as initial test data, for an SOI-based rate sensor intended for this application. The prototyped gyroscope is a single layer structure consisting of a proof mass placed in a three-fold mode-decoupled symmetric suspension. The device is fabricated in a cost-effective and highly-controllable Silicon-on-Insulator (SOI) process for in-plane inertial devices. The mechanical structure is integrated in a vacuum-sealed hermetic package with a separate CMOS readout ASIC. At the present time, the device has undergone two design iterations, with the most recent just completed.

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