Environmentally-Robust High-Performance Silicon TIMU Chip

Farrokh Ayazi, Haoran Wen, Anosh Daruwalla, Pranav Gupta

Peer Reviewed

Abstract:	This paper presents progress on the development of a high-performance single-chip timing and inertial measurement unit (TIMU) based on environmentally-robust high-frequency micromechanical devices and the hermeticallysealed HARPSS+ silicon MEMS process. The fabrication platform provides the unique capability of producing deep-submicron capacitive gaps (i.e. nano-gaps) in various orientations, including 54°-slanted electrodes, enabling low-voltage modematching and alignment of triaxial high-frequency resonator gyroscopes with high sensitivity. The resonator (i.e. modematched) gyroscopes and quasi-static accelerometers are sealed in separate cavities with different pressure levels through a single bonding step, which allows for the co-fabrication and copackaging of high-dynamic-range high-Q bulk acoustic wave (BAW) resonator 3-axis gyroscopes and critically-damped highbandwidth (above 10kHz) micro-gravity 3-axis accelerometers. High-frequency and high-Q nano-gap timing resonators with low motional impedance are fabricated on the same substrate with the IMU, which favors low-jitter high-frequency oscillator implementations and enables OCXO demonstrations with subppm stability. Fabricated devices were tested against wafer thinning process, high shocks, aging effects and extensive temperature variations, verifying the robustness of the designs and fabrication process. The high performance, high robustness, and small form factor make the HARPSS+ precision TIMUs an attractive solution for demanding inertial navigation and guidance applications.
Published in:	2020 IEEE/ION Position, Location and Navigation Symposium (PLANS) April 20 - 23, 2020 Hilton Portland Downtown Portland, Oregon
Pages:	16 - 23
Cite this article:	Ayazi, Farrokh, Wen, Haoran, Daruwalla, Anosh, Gupta, Pranav, "Environmentally-Robust High-Performance Silicon TIMU Chip," 2020 IEEE/ION Position, Location and Navigation Symposium (PLANS), Portland, Oregon, April 2020, pp. 16-23. https://doi.org/10.1109/PLANS46316.2020.9110162
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