Design and Manufacture of a MEMS Capacitive Differential Pressure Sensor with High Linearity and Low Sensitivity

Capacitive differential pressure sensors have received widespread attention in recent years. This paper reports a MEMS capacitive differential pressure sensor with low temperature sensitivity and high output linearity. Its sensitive component is a circular diaphragm with the E-shaped structure. This sensor is based on three-layer composite structure of Glass-Silicon-Glass. In the fabrication, the adhesive LOR 20B is used to bond the glass wafer and silicon wafer, and the height of the cavity is controlled to 5 μm by controlling the thickness of LOR 20B. In addition, there are many bumps fabricated by silicon dioxide on the surface of the diaphragm to prevent sensor failure. According to the results of theoretical calculation and coupling simulation between thermal expansion and electromechanical, its sensitivity is 0.050 pF/Pa, the test range is 0-1000 Pa, and the nonlinearity of the output signal is 2.85%. In addition, it can also work in the environment from normal temperature to 413.15 K, and the average temperature drift coefficient of the capacitor is 0.037% FS/K.