Reseach On The Comprehensive Simulation And Reliability Analysis Of Silicon Carbide High Temperature Pressure Sensor

Due to the performance limitations of silicon materials,silicon-based pressure sensors cannot normally work in high-temperature environments greater than 120 ?.However,SiC capacitive pressure sensors have the characteristics of high sensitivity,stable temperature and strong robustness,making them applicable to 600 ? high temperature environment.Although SiC capacitive pressure sensors have been applied in extremely harsh measurement environments,they are rarely subjected to comprehensive stress studies and failure mechanism analysis.This article mainly studies the sensor from three aspects: the design and analysis of the high linearity SiC cylindrical structure capacitive pressure sensor,the comprehensive stress simulation analysis of the SiC capacitive pressure sensor and the failure mechanism analysis.Firstly,in order to improve the linearity of the capacitive pressure sensor,a high linearity SiC cylindrical structure capacitive pressure sensor model(TCCPS model)was designed.The TCCPS model uses silicon dioxide as the dielectric contact layer,which can solve the problem of less linearity caused by the decrease of the pole distance as the pressure increases.The study found that the TCCPS model has a sensitivity of 0.9011 in the non-contact state and 0.9708 in the contact state.It can be seen that the cylindrical structure SiC capacitive pressure sensor has high linearity and robustness.Secondly,using ANSYS finite element analysis software to carry out comprehensive stress simulation analysis of chip-level and packaged sensors.Single stress includes temperature,pressure and shock;multi-stress coupling mainly includes temperature and pressure coupling and comprehensive stress of temperature,pressure and vibration.The distribution of deformation,stress and strain on the sensor is obtained through simulation.In the comprehensive stress environment simulation,the capacitance drift of the chiplevel and package-level sensors is 1.0153% and 0.9919%,respectively.At the extreme of the comprehensive stress environment,the maximum stress and maximum strain increment of the sensor sealing layer are 27 MPa and 1.3×10-4 ?m/?m,respectively.The above-mentioned finite element simulation analysis can obtain the law of zero drift,maximum stress and maximum stress change of the sensor under various stress environments,which can be used to form a method for evaluating the reliability of the sensor.Finally,the prepared sensor samples are used to carry out test experiments to further analyze the failure mechanism of the sensor.The output characteristic test shows that the linearity of the sensor in the non-contact area and the contact area are 0.9261 and 0.9603,the sensitivity is 0.1524 pF/KPa and 0.0673 pF/KPa,respectively,and the maximum hysteresis is 0.0114%.Then through constant temperature fatigue,random vibration,sinusoidal scanning vibration and shock vibration to monitor the zero output voltage change of the sensor.After analysis,the zero drift of the constant temperature fatigue of the sensor is 0.11075%,and the zero drift of the sensor after the impact vibration test is 0.10768%.Comprehensive analysis of the sensor results under various environmental stresses shows that the zero-point output drift of the sensor is less than 1%,and the sample structure is free of cracking,which meets the design specifications.