A High-Sensitivity Resonant Differential Pressure Microsensor Based on Wafer-Level Eutectic Bonding

Abstract

This article presented a high-sensitivity resonant differential pressure microsensor based on wafer-level eutectic bonding, where dual resonators were embedded in the pressure-sensitive diaphragm to sense differential pressures, and a silicon cap was used to form a vacuum cavity. Differential pressures applied to the developed microsensor caused deflections of the pressure-sensitive diaphragm, resulting in shifts in resonant frequencies. This microsensor was designed based on finite element simulations with optimized structural parameters, which indicated high differential pressure sensitivities. Micro fabrications with key processes of deep reactive-ion etching (DRIE), lithography, and wafer-level eutectic bonding were adopted for device fabrication. The following experimental characterizations were conducted, producing the differential-pressure sensitivity of 181.53 Hz/kPa, the maxing fitting error of less than 80 Pa, under the differential pressure range of 0–100 kPa, the static pressure range of 110–200 kPa, and the temperature range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C. These results show that developed resonant differential pressure microsensors have excellent performances for differential-pressure measurements.