Wafer-Level-Packaged HARPSS+ MEMS Platform: Integration of Robust Timing and Inertial Measurement Units (TIMU) on a Single Chip

Haoran Wen, Anosh Daruwalla, Yaesuk Jeong, Pranav Gupta, Jaehoo Choi, Chang-Shun Liu, Farrokh Ayazi

Abstract: This paper presents a nano-precision high aspect-ratio poly- and single-crystal silicon DRIE plus wet-etching fabrication platform, also known as HARPSS+, which enables single-chip integration and wafer-level-packaging of robust high-frequency timing and inertial sensors. The HARPSS+ platform is the first highly developed process providing scalable deep submicron gaps in vertical, horizontal, and 54°-slanted orientations for efficient transduction and dynamic control of high-Q single crystalline silicon resonators. The platform also provides wafer-level-packaging of MEMS devices in cavities with different cavity pressures in a single bonding step. Single-chip timing and inertial measurement units (TIMU) are fabricated with high yield through the HARPSS+ platform, which features 3-axis high-frequency resonant gyroscopes with complete quadrature cancellation enabled by the slanted electrodes. High-bandwidth 3-axis accelerometers are used on the TIMU with high sensitivity provided by the nano-gaps. A high-Q BAW resonator is included as internal frequency reference for self-contained timing and inertial measurement, along with on-chip heaters for ovenization capability. Each device is packaged in cavities with different pressure levels ranging from atmosphere to sub-10Torr for optimized operation through one single bonding step. The nano-gap-enabled high-frequency devices have high environmental robustness and small form-factor with the overall TIMU being 4.5mm?5.5mm?1mm. Fabricated TIMU demonstrates high-performance with sub-10°/h gyroscopes and sub-100?g accelerometers. Low power chip-level ovenization is achievable with on-chip heaters owing to small size and vacuum packaging.
Published in: 2018 IEEE/ION Position, Location and Navigation Symposium (PLANS)
April 23 - 26, 2018
Hyatt Regency Hotel
Monterey, CA
Pages: 261 - 266
Cite this article: Wen, Haoran, Daruwalla, Anosh, Jeong, Yaesuk, Gupta, Pranav, Choi, Jaehoo, Liu, Chang-Shun, Ayazi, Farrokh, "Wafer-Level-Packaged HARPSS+ MEMS Platform: Integration of Robust Timing and Inertial Measurement Units (TIMU) on a Single Chip," 2018 IEEE/ION Position, Location and Navigation Symposium (PLANS), Monterey, CA, April 2018, pp. 261-266.
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