High Reliability of MEMS Packaged Capacitive Pressure Sensor Employing 3C-SiC for High Temperature

This study develops the prototype of a micro-electro-mechanical systems (MEMS) packaged capacitive pressure sensor employing 3C-SiC diaphragm for high temperature devices. The 3C-SiC diaphragm is designed with the thicknesses of 1.0 μm and the width and length of 2.0 mm x 2.0 mm. The fabricated sensor is combined with a reliable stainless steel o-ring packaging concept as a simple assembly approach to reduce the manufacturing cost. There is an o-ring seal at the sensor devices an advantageous for high reliability, small size, lightweight, smart interface features and easy maintenance services. The stability and performance of the prototype devices has been tested for three test group and measured by using LCR meter. The prototypes of MEMS capacitive pressure sensor are characterized under static pressure of 5.0 MPa and temperatures up to 500 °C in a stainless steel chamber with direct capacitance measurement. At room temperature (27 °C), the sensitivity of the sensor is 0.0096 pF/MPa in the range of pressure (1.0–5.0 MPa), with nonlinearity of 0.49%. At 300 °C, the sensitivity is 0.0127 pF/MPa, and the nonlinearity of 0.46%. The sensitivity increased by 0.0031 pF/MPa; corresponding temperature coefficient of sensitivity is 0.058%/°C. At 500 °C, the maximum temperature coefficient of output change is 0.073%/°C being measured at 5.0 MPa. The main impact of this work is the ability of the sensor to operate up to 500 °C, compare to the previous work using similar 3C-SiC diaphragm that can operates only 300 °C. The results also show that MEMS packaged capacitive pressure sensor employing 3C-SiC is performed high reliability for high temperature up to 500 °C. In addition, a reliable stainless steel o-ring packaging concept of MEMS packaged capacitive pressure sensor.