Digital Type CMOS-MEMS Cointegrated Pressure Sensor Fabricated Using Cost-Effective Minimal-Fab Process

The digital type CMOS-MEMS cointegrated pressure sensor with a CMOS ring oscillator on a thin diaphragm was fabricated using cost-effective minimal-fab process and the successful operation of the fabricated pressure sensor was demonstrated, for the first time. It was confirmed that about 40 kHz difference in the oscillation frequency is observed in the fabricated CMOS-MEMS cointegrated pressure sensor chip by changing pressures from -40 to +40 kPa. This result is originated from the drain current variations of the longitudinal
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channel PMOSFETs of the CMOS ring oscillator owing to the piezoresistive effect. The developed CMOS-MEMS cointegrated pressure sensor is suitable for the application to the potable IoT sensor systems because it has a low-power consumption due to its all CMOS integration.