A Resonant Differential Pressure Microsensor With Stress Isolation and Au-Au Bonding in Packaging

Resonant differential pressure (DP) sensors are prone to environmental disturbances [e.g., temperatures ( ${T}$ ) and static pressure (SP)] due to poor packaging. In order to address this issue, this article presents a resonant DP microsensor where the core pressure-sensitive element was assembled with the packaging house using stress isolation and Au–Au bonding. The stress isolation was used to reduce the effect of packaging house on the core-sensitive element when the environmental disturbances of temperature and SP varied, and the Au–Au bonding was used to improve the structural stability to reduce the frequency drift over time. Numerical simulation was conducted to confirm the positive effect of including the stress isolation structure and fabrication processes were developed to realize Au–Au bonding in packaging. Experimental characterization was conducted, reporting reductions of three times in temperature disturbance, 25 times in SP disturbance, and 35 times in frequency drift in comparison with the counterpart without stress isolation and Au–Au bonding. Based on these improvements, the accuracy of the developed resonant DP microsensor was quantified as 0.03%FS within the DP of 0–100 kPa, the temperature of −10 °C to 60 °C, and the SP of 110–200 kPa.