Research On The Mechanism And Characteristics Of IE-Bi-MCT

With the wide application of high-power semiconductor devices in the fields of transportation,smart grid,new energy and consumer electronic products,the performance and reliability of devices are increasingly required.In order to further reduce the on-state loss and improve reliability of high-power devices,this paper proposes a new electron injection enhanced dual-mode MOS controlled thyristor(IE-Bi-MCT)structure,which introduces a carrier storage layer into a base resistance controlled thyristor(BRT).This IE-Bi-MCT has a very high turn-off capability at low on-voltage drop,and effectively suppress the snapback effect of BRT and avoid latch up effect of IGBT.The main research contents are as follows:Firstly,taking 6.5-kV IE-Bi-MCT as an example,the structural characteristics and operation principle of IE-Bi-MCT are analyzed;the structure is modeled using TCAD software,and the characteristic curve of IE-Bi-MCT is analyzed by analyzing Carrier concentration distribution,current density distribution and electric field distribution,etc.,The results show that the new device needs to apply a negative bias to the gate when blocking;the positive bias applied to the gate can be operated in dual mode of IGBT and thyristor;at this time,even if the gate bias is removed,the single mode of thyristor can still be operated;when the gate is turned off,a negative bias voltage is applied to the gate,which can turn off the larger anode current.Secondly,the I-V characteristics of IE-Bi-MCT and BRT devices are compared and analyzed,and the snapback phenomenon and its suppression mechanism are studied.The results show that the new device can effectively suppress the snapback phenomenon and greatly reduce the on-state loss of the device.Thirdly,the influencing factors of the maximum turn-off current density of IE-Bi-MCT are studied,the influence of key structural parameters,temperature and other changes on the static and dynamic characteristics of the device and the snapback phenomenon are analyzed,and the optimal structural parameters are extracted.The results show that there is a close correlation between each structural parameter,and the proper selection of structural parameters can avoid the occurrence of snapback at low temperatures.Fourthly,comparing the characteristics of IE-Bi-MCT with BRT and IGBT at the same voltage level,the results show that,under the same blocking voltage,IE-Bi-MCT can not only suppress the snapback phenomenon,but also suppress the snapback phenomenon.It has better current turn-off capability;compared with IGBT,IE-Bi-MCT has lower on-state voltage drop.Lastly,the key process of IE-Bi-MCT and its compatibility with IGBT process are analyzed,the process flow is formulated,and the process conditions are extracted through process simulation.The research results can provide theoretical guidance for the development of high voltage MOS gate control devices.