Research On Key Structure Test Characterization And Failure Mechanism Of Silicon Carbide High Temperature Pressure Sensor

With the development of sensor technology,the application of silicon carbide high temperature pressure sensor is more and more widely.In recent years,researchers at home and abroad are mainly devoted to the establishment of sensor simulation models and the study of output characteristics,the production of sensor finished products and the research of reliability testing,and the study of sensor failure analysis.There are few reports on the performance degradation analysis and failure mechanism of SiC high-temperature pressure sensors under various stresses.The influence of the failure of the insulating structure on the silicon carbide high-temperature pressure sensor cannot be ignored,and the failure mechanism is still unclear.Therefore,it is necessary to test and characterize the insulating structure of silicon carbide high temperature pressure sensor and study the failure mechanism.In this paper,the test and characterization method of the insulating structure of silicon carbide high-temperature pressure sensor was firstly studied by ellipsometry,stress-strain method,dielectric loss test and cross-sectional morphology analysis,and a test and characterization method based on the characteristics of the insulating structure of silicon carbide high-temperature pressure sensor and processes.The conversion relationship between the dielectric loss test parameters of the chip structure and the insulation structure was proposed,and the failure criterion of the dielectric loss of the insulation structure of the sensor was given.Carried out the test and characterization of the sensor insulation structure samples for different treatment processes and temperatures?600?-900??,and discussed the test data and the correlation analysis of the characterization methods.The test results show that the annealing process has the greatest impact on the properties of the SiO₂material.The dielectric loss of the unannealed samples is greater than the proposed standard value of 0.0347,and the maxim?m refractive index deviation in the ellipsometric test can reach 0.04,and the refractive index change rate can reach 2.7%;The temperature also has a great influence on the failure of the sensor insulation structure;the single-layer interface model and the multi-layer interface model of the ellipsometry test of the insulation structure were established,which confirms that the SiC/SiO₂ interface is a transition interface,and the refractive index of the interface layer changes with the depth of the interface In the stress-strain test,the film curvature method was used to calculate the film stress,and it is found that the temperature and the stress have a positive correlation;in the SEM cross-sectional morphology analysis,the interface condition at high temperature is lower and the temperature is more complicated.In each test,the effect on the test result is the annealing process,processing temperature,and processing time in that order.Through the finite element simulation software ANSYS Workbench,the stress and strain of the sensor insulation structure and the chip structure at high temperature of600?-900?were simulated.The creep characteristics of SiC and SiO₂ materials were analyzed,and the constitutive equations that conform to the creep of SiO₂ materials were determined.The simulation results of the sensor insulation structure show that the creep stress increases with increasing temperature,and the stress value at 900?is524.6MPa.For the sensor chip structure,the weak point of the structure was obtained by simulation,and the zero drift rate of the sensor output capacitance was calculated using the simulation results.Finally,the failure mechanism of the insulating structure of silicon carbide high temperature pressure sensor was studied.The equivalent capacitance model was established by means of stacked capacitance,on this basis,the output capacitance of the sensor and its zero drift were calculated,The zero drift at 900°C is 0.94%.the relationship between performance and structure and parameters was analyzed,and the failure judgment was completed according to the test standard,and the sensor insulation structure was finally obtained failure mechanism and give suggestions for improvement.