Research On Short-circuit Failure Models And Failure Mechanisms For SiC MOSFET And SiC JFET

Throughout the breakthroughs in technology in recent years,the research and application of power semiconductor devices are constantly improving,and its application fields are constantly expanding.The Si material has good electrical conductivity and is the germination of device development in the semiconductor industry,opening the beginning of application in the electronics industry.However,in high-power electronics applications,SiC power devices have sprung up and have shown advantages over traditional Si devices.Among all SiC devices,SiC MOSFETs and SiC JFETs are the best choice.In order to better use the silicon carbide device products,it is especially important to establish a precise failure model that accurately reflects the short-circuit failure of the two devices and analyze the short-circuit failure mechanism.This paper briefly introduces the basic theory of SiC MOSFET and SiC JFET,and focuses on the basic theory of the short-circuit failure model construction of the two devices and verifies them.Based on the simulation integrated environment of Matlab/Simulink,a more accurate channel mobility degradation mechanism module is constructed for the two devices.The SiC MOSFET model will reflect the mobility of the SiC/SiO₂ oxide layer instead of the constant mobility of the conventional MOSFET.Similarly,SiC JFETs consider the mobility associated with temperature and electric field to replace the constant mobility of conventional JFETs.For the problem that the SiC MOSFET contains gate oxide instability,an additional gate leakage current is added;both devices generate leakage current under high current stress,and three currents are introduced across the drain and source.The reverse biased PN junction leakage current of the composition.Comparing the short-circuit failure model output data of MOSFET and JFET with the experimental data and the measured data of the literature,the results strongly prove that the established short-circuit failure model has good accuracy.Under the short-circuit condition,the short-circuit failure mechanism of the device was studied by using Matlab/Simulink simulation software to analyze the failure current.The internal failure mechanism of SiC MOSFET and SiC JFET was analyzed by TCAD semiconductor device simulation software to analyze the internal SiC MOSFET and SiC JFET device.The physical properties such as current density distribution and flow direction trend,and the critical failure energy and withstand time of the two are compared.The results show that SiC JFET has better short-circuit robustness than SiC MOSFET.In order to further explore the short-circuit failure mechanism of SiC MOSFET,based on the short-circuit failure model of SiC MOSFET,the numerical model of short-circuit failure of Si MOSFET was established by TCAD simulation software.The short-circuit failure mechanism of SiC MOSFET and Si MOSFET was compared by experimental data.The reason for the failure is analyzed.The results show that the failure of SiC MOSFET is mainly due to the high temperature of the device,which causes the melting of the metal electrode and the damage of the gate oxide layer.The short circuit failure of the Si MOSFET is due to the parasitic BJT in the structure.The resulting leakage current causes damage to the device.At the end of the short-circuit failure condition,based on the established SiC MOSFET short-circuit failure model,the influence of SiC/SiO₂ interface state charge and gate resistance on the short-circuit current of SiC MOSFET is discussed and discussed,and the effect on device failure time is discussed.The results show that larger gate resistance and higher interface state charge can delay short-circuit failure of SiC MOSFET.