Optimization Design And Simulation Study Of High Voltage 4H-Si C Trench MPS Diode

In recent years,With the rapid development of power electronic systems,Power devices are required to have lower power consumption,higher reverse blocking voltage and faster switching speed.Therefore,Power diodes should have the characteristics of low forward voltage drop,high reverse blocking voltage and fast switching speed,Which is the main research direction and goal.Meanwhile,Since the development of Si power diodes is close to the theoretical limit of materials,Si C with high critical breakdown electric field,wide band gap width and high thermal conductivity has become a kind of ideal material to improve the performance of power diode.Si C megered Schottky and PiN(MPS)is increasingly valued for high breakdown voltage and low positive voltage drop.In this paper,Characteristics of forward on-state,reverse blocking and reverse recovery of trench megered Schottky and PiN(TMPS)diode is studied.It has forward on-state voltage and switching speed comparable to Schottky diode,and a reverse blocking ability comparable to PiN diode for TMPS diode with better comprehensive performance.The influence of structure parameters of TMPS diode is studied by numerical simulation.The characteristics of forward,reverse blocking and switching are analyzed.The main research is as follows:(1)The basic working principle and design of TMPS diode cell structure were analyzed theoretically.TMPS diode cell structure with a theoretical reverse blocking voltage of 4800 V was designed.(2)Simulation of TMPS diode based on Silvaco software.Firstly,the forward,reverse blocking and reverse recovery of TMPS diode were simulated.Secondly,the effects of the width of the P+region and the width of the Schottky contact for the forward,reverse blocking and reverse recovery were simulated.Finally,the relationship between the doping concentration in the drift region and the forward,reverse blocking and reverse recovery was also simulated.Through theoretical analysis and numerical simulation,the following results are obtained:(1)When the width of the P~+region increases,the ratio of on-state resistance increases,reverse recovery time is longer,and reverse blocking voltage remains unchanged.Therefore,in the case of P~+N~-junction conduction,the smaller P~+region,the better.(2)For TMPS structure with a breakdown voltage of 4800 V.Turn-on voltage increases with the decrease of WS that is less than 2?m.Turn-on voltage is determined by the Schottky barrier and has nothing to do when W_S is greater than 2?m.The ratio of on-state resistance decreases with the increase of WS in the small current phase of forward on-state,while in the large current phase,it increases with the increase of WS.When WS is less than or equal to 1.7?m,Schottky contact is completely shielded,and the breakdown voltage is basically unchanged with W_S.When W_S is greater than 1.7?m,the shielding ability of P~+N~-to Schottky contact is weakened,and the breakdown voltage decreases with the increase of W_S.Between 1.1 and1.7?m,the reverse recovery time is shorter.When W_S is less than 1.4?m,the peak current increases with the decrease of WS,and the switching power consumption increases.When WS is large,Characteristic of soft recovery is better,and has higher working stability and reliability.Compared with flat MPS,TMPS has high reverse blocking ability,high working stability and reliability when WS is larger.(3)With the increase of doping concentration in the drift area,the ratio of on-state resistance and breakdown voltage decrease,reverse recovery peak current and recovery time increase.However,the soft recovery characteristics are better with the increase of doping concentration in the drift area.The TMPS has high reverse breakdown voltage,high working stability and reliability under high doping concentration of drift region.In this paper,the forward,reverse and reverse recovery characteristics of TMPS with different P~+zone width,Schottky contact width and drift zone doping concentrations are studied,which has certain guiding significance for improving the characteristics of TMPS diode.The relationship between the width of P~+zone,the width of Schottky contact and the characteristics of TMPS diode,which has reference value for reducing the device area and improving the switching speed.