Research Of SEB Hardening For 4H-SiC Power MOSFET

With the development of the power electronics industry,higher requirements are put forward for power devices.The excellent performance of silicon carbide power MOSFET(Metal Oxide Semiconductor Field Effect Transistor)devices in high temperature,high frequency,high voltage and radiation hardened has attracted the attention of researchers and has broad application prospects.With the further development of China’s aerospace industry,the power devices working in radiation environment are also more susceptible to radiation effects(such as single event effects).At present,most of the research results are applied to the radiation environment of lower energy particles,and there is no unified evaluation standard and mature hardening design for the hardening of higher energy particles.In view of this,this paper studies the single event burnout(SEB)mechanism and hardening method of 4H-SiC power MOSFETs under the higher energy particles condition.The purpose is to propose a more feasible hardening design method,and improve the device’s SEB performance while the basic electrical performance is not greatly affected.First,the SEB mechanism of power MOSFETs and related performance characterization are studied,and a hardening method based on the SEB performance characterization of traditional devices is proposed.The highest temperature in the device is used to determine whether SEB occurs and to evaluate the effect of hardening design.The simulation results show that the incidence of higher energy particles will cause the temperature in the device to increase sharply beyond the melting point of SiC(about 3100K)and significantly reduce the reliability of the device.Secondly,the UMOSFET based on a multi-buffer layer and extended P-body(MBEP-MOSFET)device is proposed and its SEB performance are characterized under the higher energy particles condition.The simulation results show that the multi-buffer layer can effectively reduce the high electric field generated by the Kirk effect at the N-epi/substrate homojunction of the device.Together with the extended P-body region,it reduces the transient current and the temperature to 1724 K.And the added structure has little effect on the conduction performance of the device.This paper also discusses the influence of added structural parameters on the hardened effect,and supplements the SEB effect mechanism by analyzing its principles.Subsequently,this paper gives the process flow of MBEP-MOSFET and analyzes its feasibility.Finally,the integrated transistor VDMOSFET(IBJT-VDMOSFET)based on the same hardening method is proposed and its SEB performance are characterized under the higher energy particles condition.The simulation results show that the added structure can obtain the same effect but the SEB performance is inferior to MBEP-MOSFET.Combining with the structure of MBEP-MOSFET,the reasons for its poor hardened effect are analyzed,and an improvement method is proposed.This paper also gives the process flow of IBJT-VDMOSFET.Because the process of silicon carbide VDMOSFET is more mature,it still has a good research prospect.