High and Moderate-Level Vacuum Packaging of Vibratory MEMS

We report vacuum packaging procedures for low-stress die attachment and versatile hermetic sealing of resonant MEMS. The developed in-house infrastructure allows for both high and moderate-level vacuum packaging addressing the requirements of various applications. Prototypes of 100 μm silicon-on-insulator Quadruple Mass Gyroscopes (QMGs) were packaged using the developed process with and without getters. Characterization of stand-alone packaged devices with no getters resulted in stable quality factors (Q-factors) of 1000 (corresponding to 0.5 Torr vacuum level), while devices sealed with activated getters demonstrated Q-factors of 1.2 million (below 0.1 mTorr level inside the package). Due to the high Q-factors achieved in this work, we project that the QMG used in this work can potentially reach the navigation-grade performance, potentially bridging the gap between the inertial silicon MEMS and the state-of-the-art fused quartz hemispherical resonator gyroscopes.