Development of CMOS Micromachined Capacitive Squeeze-Film Pressure Sensors

Squeeze-film damping due to compressed thin-film gas comprises both the viscous and elastic effects. Based on the latter, this work reports two capacitively-transduced resonant pressure sensors implemented in a complementary metal oxide semiconductor (CMOS) process to provide sensor miniaturization, integration and sensitivity enhancement. Post-CMOS fabrication is simplified as a sealed membrane in conventional pressure sensors is not required. The squeeze-film elastic effect enhanced by the narrow sub-μm gap leads to improved sensitivity and reduced sensor size. The two designs have resonant plates of 200 × 200 and 100 × 100 μm
²
, and demonstrate sensitivities of 0.77 and 5.34 Hz/Pa, respectively.