Research On Key Preparation Technology Of Silicon Carbide Membrane Fiber Optic High Temperature Pressure Sensor

The real-time measurement of pressure parameters under high temperature and hash environment is an urgent need in military and civilian fields.The pressure sensor technology applied in high temperature environment has became an important research direction.As a third-generation semiconductor material,silicon carbide has excellent thermal,mechanical and electrical properties in high temperature environment,so it is very suitable as a base material for MEMS high temperature pressure sensors.Compared with similar electronic sensors,fiber optic high temperature pressure sensors have the advantages such as high temperature resistance,high temperature response stability,anti-electromagnetic interference and low cost.They have been widely used in the health monitoring of aviation engine and the environment detection of oil well.Using silicon carbide material to prepare fiber optic high temperature pressure sensor and carry out related research work is significant to the development of high temperature pressure sensor technology.Based on the principle of Fabry-Perot interference,combined with the sensing mechanism and testing principle of membrane fiber optic pressure sensor,the whole structure of the sensor is modeled,and the specific structural size parameters are determined through theoretical analysis and numerical calculation.Static analysis and temperature-pressure coupling analysis of the sensitive model of silicon carbide membrane fiber optic pressure sensor were carried out using the finite element analysis software COMSOL to simulate the performance of the sensor in a composite environment.Based on the modeled sensor structure and the existed micro-nano processing technology,the design of processing flow and the preparation of the sensitive head were completed.Meanwhile,the key processes in the preparation process were analyzed and summarized.Finally,the process quality of silicon carbide bonded sample was tested,and the test results shown that the bonding quality of the sample was good,there were almost no voids around the bonding interface,and the bondingstrength exceeded 7.5 MPa,which is higher than the minimum bonding strength standard of MEMS devices.And it was worth mentioning that the bonding sample had high performance in air tightness.At the same time,based on the FISO demodulation system,the normal temperature pressure test platform and the temperature-pressure composite test platform were built to test the pressure sensitive performance of the sensor at normal temperature and high temperature.The sensitivity of the sensor at room temperature was 918 nm/MPa,and the hysteresis was less than 0.2%.The nonlinear error of the sensor is less than 0.37% and prensted a good pressure sensitive performance in the range of 500 ?.This paper provides a reference for the optimization and improvement of silicon carbide membrane fiber optic pressure sensor in the future.