Research On Design And Preparation Of SiC-based Wireless High-temperature Pressure Sensor

Given that the traditional silicon-based MEMS pressure sensor has some limitationswhen using at high temperature, humidity and other complex environments, the paperdesigned a SiC-based wireless high-temperature pressure sensor, which can overcomesensitive structural instability and electrical lead performance degradation for traditionalpressure sensor working at high-temperature environment. As a new third-generation wideband gap semiconductor material, SiC material semiconductor device can adapt to hightemperature, high frequency, high power working conditions. Considering the MEMSprocessing technology for SiC material continues to mature, preparation of SiChigh-temperature pressure sensor has important practical significance.Combining with the present research status，the paper elaborated the principle, structuraldesign and preparation, and other related structural verification of SiC-based high-temperaturepressure sensor. According to the principle of mutual coupling of electromagnetic induction,the external pressure can change the resonant frequency of the variable capacitance sensorcircuit which in turn causes the significant changes of equivalent impedance of the test loop.Effective information of the external pressure is obtained by observing the variation of thischaracteristic. The wireless coupling measurement is to avoid the electrical leadinterconnection between devices which can be used in high temperature and other harshenvironments.The capacitor and inductor structure model of the high-temperature pressure sensor wasestablished in the paper, and the design of structure parameter was presented in details. At thesame time in order to verify the reasonableness of the design of the capacitor structure, thepaper provided ANSYS simulation and theoretical analysis for the deflection and stresses onthe sensitive membrane structure, and gave the deflection and stress curve within the range ofpressure changes. Combined with the design of sensor and the existing MEMS processing technology, a preparation scheme was developed in this paper, the key techniques and processvalidation involved were analyzed in details.Finally, capacitor varistor structure was prepared using silicon material instead of siliconcarbide material in order to test the sealing performance of the capacitor cavity, and analyzethe sealing problems of chips. The capacitor and PCB inductor coil were connected by wirebonding to form a wireless capacitive pressure sensor, and the sensor was tested underuniform pressure at a room temperature. The test results show that using the wireless passivecapacitor pressure sensor fabricated by MEMS technology is feasible in practice.