The Simulation Study On MPS Diode Of Novel SiC Deep Groove Structure

Compared with Ge,Si and other traditional semiconductor materials,the third generation semiconductor materials(SiC)have excellent material properties:wide band gap?high breakdown electric field?high thermal conductivity and high saturated electron drift speed.It is the most ideal material for the manufacture of power electronic devices in high temperature?irradiation?high power and other harsh environments.The merged pin Schottky(MPS)diode is the most ideal power diode with the characteristics of small opening voltage?large on current?fast switching speed?small reverse leakage current and high breakdown voltage.It combines the good forward characteristic?switching characteristic of SBD diodes and excellent breakdown characteristic of PiN diode's.The excellent material properties of SiC and the excellent structure advantages of MPS diode make SiC MPS diode the most potential power diode.In this thesis,we first use TCAD to analyze the internal energy band of MPS diode,and reveal the physical mechanism behind the larger opening voltage of PN junction in MPS diode than that of PiN diode.Then,the influence of the structure parameters of MPS diode on the bipolar conduction voltage is studied,and a simple analytical model is given.The calculation results of the model are basically consistent with the simulation results.The next step is to analyze the influence of structure parameters on the forward conduction and breakdown characteristics of planar MPS diodes.Finally,the surge process of MPS diode is analyzed,and the influence of structure parameters on surge characteristics is studied.For the traditional groove structure MPS diode,the influence of groove depth on the forward and reverse blocking characteristics of the device is studied by simulation.By changing the barrier height and Schottky width of the groove structure,the forward and breakdown characteristics are compared with the plane structure,which proves the advantages of the groove structure.Moreover,the surge characteristics of the groove structure are more superior.At the groove depth of 1.5?m,compared with the plane structure,the maximum junction temperature is reduced by 12%,and the bipolar conduction voltage is reduced by 20%In order to improve the forward conduction characteristics of the trench,a new type of oxide trench MPS diode structure(TOMPS)is proposed.Compared with the traditional trench structure,it can significantly improve the forward characteristics when the reverse degradation is not serious.Because of charge sharing,under the same on-resistance,the cell size is reduced by 10%compared with the plane structure,and the bipolar on voltage is reduced by 2.3%compared with the traditional groove structure.Finally,the influence of structure parameters on the structure characteristics of TOMPS diode is studied.