Stress Model Research Of SIC High Temperature Pressure Sensor Structure

With the development of science and technology,silicon carbide high temperature pressure sensors are widely used in petroleum drilling,chemical metallurgy,aerospace and other fields.At present,domestic and foreign researches are mainly devoted to sensor structural design optimization and failure analysis,and ohmic contact structure design and failure analysis.There are few reports on the stress model of silicon carbide high-temperature pressure sensors.In the aerospace field where high-temperature pressure sensors are widely used,sensor failure may cause huge property losses and even endanger human life.Therefore,study the stress model of the silicon carbide high temperature pressure sensor structure under different stresses,especially the comprehensive stress,and quantitatively describe the relationship between the sensor's reliability characteristics and the accelerating stress level,and provide the reliability assessment and life span of the sensor structure under different stresses.The basis for forecasting is an urgent problem to be solved,and it also has important theoretical and engineering significance.This article first introduces and analyzes the characteristics and scope of application of common failure physical models and reliability distribution models.At the same time,it analyzes and studies the reliability model distribution fitting evaluation methods and parameter estimation methods commonly used in engineering.Based on the working principle of the silicon carbide high temperature pressure sensor,a stress model of the silicon carbide high temperature pressure sensor structure is proposed,and a reliability analysis method suitable for the structure of the silicon carbide high temperature pressure sensor is determined and formed.The reliability and stress model of the insulating structure of the silicon carbide high temperature pressure sensor at high temperature are studied.Based on the working principle of the insulation structure of the sensitive element,the combined effect of the structural deformation of the sensitive element and the change of the silicon dioxide dielectric parameter at high temperature on the key evaluation parameter of the insulation structure of the sensitive element-capacitance zero drift is studied by the method of combining simulation and experiment.The simulation studies respectively the deformation and capacitance zero drift of the insulation structure at 600?,700?,800?,900?for 1h,2h and 4h.At the same time,the dielectric parameters of SiC/SiO₂ samples under the same temperature and time stress were tested and the capacitance zero drift was corrected based on the test results.The electrical parameter life of the insulation structure at different temperatures is calculated based on the zero drift of the capacitance.The life data analysis shows that the life of the insulation electrical parameters of the sensitive element under temperature stress is Weibull distribution.At the same time,the insulation structure of the sensitive element is obtained at temperature based on the reliability distribution.The median lifetimes at stresses of 600?,700?,800?,and 900?are 819h,381h,207h,and 120.2h,respectively.Furthermore,the modified Arrhenius model is used to characterize the stress model under the temperature stress of the insulating structure of the sensitive element.In the stress model,the failure activation energy is 0.668e V,and the temperature correction factor m is-1.32.Based on 54pcs Pt/Ti N/Ti/SiC ohmic contact electrode structure high temperature test samples prepared,the reliability and stress model of the ohmic contact electrode structure at high temperature were studied.The specific contact resistivity,the key parameter of the ohmic contact structure,was calculated through testing and analysis.The results showed that the life distribution of the ohmic electrode contact structure of the experimental sample obeys the Weibull distribution,and the median life of the ohmic contact at 600?is 4.8h.In addition,on the basis of comprehensive experimental data and literature analysis,the Arrhenius model is used to characterize the stress model of the Pt/Ti N/Ti/SiC ohmic contact structure,and the failure activation energy in the ohmic contact structure stress model is analyzed.The median lifetime of the ohmic contact structure prepared in this paper at 700?is calculated by the stress model.Based on the working principle of the silicon carbide high temperature pressure sensor structure,its stress model under temperature stress conforms to the weakest ring model,which depends on the weakest point of the device,namely min{insulation structure,ohmic contact structure}.The reliability and stress model of the silicon carbide high temperature pressure sensor structure under the comprehensive stress of temperature-pressure-shockvi bration are studied.In order to improve the simulation speed and reduce the difficulty of solving,this paper adopts the equivalent static load method to transform the carrier from the key position,carries out the analysis and research of the equivalent conversion method between temperature,pressure,and impact stress,and combines the simulation results to establish each The mathematical relationship of stress equivalent conversion simplifies and realizes the research of comprehensive stress.Using the method of simulation and experiment,the insulation electrical parameter life of the sensitive component under comprehensive stress is obtained as Weibull distribution,and the median life of the insulation structure of the sensitive component under different comprehensive stress is obtained based on the reliability distribution model.The Ailin model is used to characterize the stress model of the insulation structure of the sensitive element under the comprehensive stress.The activation energy of failure is 0.7126e V when the environmental stress is temperature-pressure,and the correction factor of the pressure stress to the model is C=14.68,D=-0.77;The environmental stress is temperature-pressure-impact activation energy is 0.723e V,the correction factor of pressure stress to the model is C=14.68,D=-0.77,the correction factor of impact stress to the model is F=3.38×10^-6,G=-1.8×10^-7.In addition,this article also analyzes the degradation rate under different stress levels based on the stress model,and determines that when the device is subjected to multiple stresses,the relationship between the stresses is not a simple superposition.The research results of this paper provide method guidance for the reliability life prediction under different environmental stresses,and provide important information basis for improving the performance and reliability of the device.