Fluid damping modeling for MEMS sensors operating in the 10 kHz-100 kHz range in near vacuum

The work proposes and experimentally verifies a new model for the prediction of the quality (Q) factor of MEMS operating in fluid damping regime in near-vacuum, with sub-2-μm gaps, in a range of frequencies extending from ∼10 kHz (typical of state-of-the-art inertial sensors) up to 100 kHz. Such frequency range is expected to be of interest for next-generation inertial sensors; yet the quasi-static approximation, holding when the time of flight of molecules between MEMS surfaces is small with respect to the shuttle oscillation period, gradually becomes invalid with increasing frequency, claiming for new modeling tools. The proposed method is validated through eight different test structures with varying resonance frequency and air gap. The agreement between Q factor prediction and measurement is within 8% even at the highest frequency.