Research On Breakdown Voltage Of NJFET And TMBS Termination

With the development of the driverless,artificial intelligence and robotics industries,the demand for power devices is becoming more and more urgent in the market,so research on power devices becomes increasingly important.Breakdown voltage,one of the most important parameters of the power device,limits the application range of the power device to a large extent.In the lateral power devices LDMOS and JFET,Resurf technology is often used to reduce the surface electric field of the device and to alleviate the contradiction among breakdown voltage and on-resistance.In the rectifier circuit,TMBS has received extensive attention due to its excellent high frequency characteristics and the ease of adjustment of its structural parameters.Power TMBS is a discrete device,and the breakdown voltage of discrete devices is often limited by the withstand voltage of the edge structure.In the edge region,the voltage of the edge structure is often lower than the breakdown voltage of the cell because there is no protection of the repeating cell.For TMBS,the trench-type edge termination structure can reduce the process complexity to a certain extent and reduce the manufacturing cost of TMBS.This paper studies the breakdown voltage of NJFET and the breakdown voltage of TMBS termination.The content is as follows:Firstly.Based on the structure of a 60 V NJFET,a novel assisted-depletion NJFET is presented,the key feature of this new structure is a buried P-BOT layer by implanting boron in the P-Sub and the region between Gate and Drain,P-BOT layer assists depletion of the NWell to improve breakdown voltage by preventing the premature from transverse breakdown.The key steps of the NJFET process have been simulated by Sentaurus TCAD,and the breakdown voltage also has been simulated.The results shown that the breakdown voltage of the proposed NJFET structure has been improved to 104 V,which is enhanced up by 57.6%.Moreover.The relation between breakdown voltage of NJFET and the design parameter of P-BOT layer is discussed,including the lithography window and dose of P-BOT layer,respectively,the distance of between P-BOT layer and both P-Body and Drian.Among them,the dose of P-BOT layer and the distance of between P-BOT layer and both P-Body and Drain are closely related to breakdown voltage.Then,some parameters which are related to the breakdown voltage of TMBS termination are discussed.The Process of TMBS termination is simulated by Sentaurus TCAD,and the relation between the length of plate?trench width and depth and breakdown voltage is discussed.The results shown that breakdown voltage will achieve the maximum when trench is covered by plate.The “MOS Spacer” have effect with the relationship between length of trench and breakdown;Moreover.The result also shown that the breakdown voltage will increase to the maximum as the trench widen.Breakdown voltage has a different relationship with trench depth in different trench width.