An Integrated Dual-Mode MEMS Pressure Sensor With Piezoresistive and Capacitive Sensing via a Heterogeneous Fabrication Process

This letter presents the design methodology and heterogeneous fabrication process of a novel dual-mode microelectromechanical systems gas pressure sensor that vertically integrates piezoresistive and capacitive sensing mechanisms. The vertical integration is realized through heterogeneous fabrication techniques, including Au–Au thermocompression bonding and a noncoplanar comb capacitor structure. Finite element simulations conducted over a temperature range of 0–100 °C reveal thermal full-scale output drifts of −0.34% F.S.(Full Scale)/°C for the piezoresistive mode and 0.053%F.S./°C for the capacitive mode, highlighting the superior thermal stability of the capacitive sensing approach. Experimental characterization at 20 °C across a pressure range of 0–10 bar demonstrates sensitivities of 15.5 mV/bar and 66.4 fF/bar for the piezoresistive and capacitive modes, respectively, with nonlinearities of 1.05% F.S. and 5.56% F.S.