The Influence Of High Temperature Reliability Experiments On The Characteristic Parameters Of SiC MOSFET

Traditional semiconductor materials,such as Si,GaAs,etc.,have become increasingly difficult to meet the increasingly demanding needs of the manufacturing industry.Therefore,the third-generation semiconductor materials such as silicon carbide and gallium nitride have attracted wide attention from researchers in the power semiconductor industry with more ideal material properties.Among them,4H-SiC has high reliability epitaxy,high electron mobility,ultra-high band gap,large electron saturation drift speed,large critical breakdown field strength,low mobility,and low anisotropy.With excellent characteristics such as heterosexuality,power devices using it as a substrate have been widely used in power grids,ships,high-speed trains,electric vehicles and other fields.Among many power electronic devices,SiC MOSFET have been used in UHV DC transmission,electric vehicles and other fields due to their excellent high-frequency characteristics,high-temperature characteristics,and high-speed switching characteristics.In recent years,china has also paid more and more attention to the research and development of silicon carbide power electronic devices.In the process of commercialization,high-temperature gate bias and high-temperature reverse bias tests can verify the high-temperature reliability of SiC MOSFET.By comparing the changes in the dynamic and static characteristics of the device before and after the test,the relevant characteristics of domestic devices can be studied.This article first studied the influence of the measuring instrument on the test results of the static characteristic parameters of the SiC MOSFET.Through comparison with AGILENT B1505A,it is verified that the LMSYS test bench designed for the testing of high-power power electronic devices is not suitable for the dynamic and static characteristics of low-and medium-voltage silicon carbide devices..Then standard deviation,skewness,kurtosis,deviation and coefficient of variation were used to evaluate the dynamic and static characteristics of the silicon carbide MOSFET.On-resistance Rds(on),threshold voltage VGs(th),transconductance gfs,drain-source capacitance CDS,The dispersion of gate-drain capacitance CGD,gate-source capacitance CGS,rise time tr,fall time tf,turn-on delay td(on)and turn-off delay td(off).A parallel current sharing experiment of dual devices is designed,and the effects of device on-resistance Rds(on)and threshold voltage VGS(th)on the current distribution between devices are analyzed.Finally,a high-temperature comprehensive test platform that can perform HTGB and HTRB tests at the same time was built,and high-temperature reliability tests of 30 devices were carried out.The dynamic and static characteristics of 30 devices before and after the high-temperature test were measured,and the high-temperature reliability tests were determined by fitting analysis.It will affect the threshold voltage and transconductance of the device,but has almost no effect on on-resistance and inter-electrode capacitance.In addition to the threshold voltage,most of the static characteristic parameters of the device after the high-temperature reliability test show an upward trend.And through the fitting curve between the change rate of the device characteristic parameters before and after the test and its parameter value,it is determined that the parameter change rate and its parameter value are basically negatively correlated.Finally,based on the test results,a threshold value suitable for the high reliability requirements of 1200V/20 A SiC MOSFET is proposed.After the above threshold value is met,the characteristic parameter change rate of the device before and after the high temperature reliability test can be controlled within 8%,thereby improving the device performance Reliability in long-term high temperature environments.