Design And Characteristics Research Of SiC Trench MOSFET

Owing to the excellent material properties of wide bandgap,high critical breakdown electric field,high thermal conductivity,high electron saturation drift velocity and so on,Silicon Carbide?SiC?can be widely used in high power density fields,such as photovoltaic inverter,automotive electronics,and power transmission.As the second generation of SiC MOSFET,SiC Trench MOSFET?TMOS?has higher channel densities and lower on-resistances,compared with planar MOSFET.This paper simulated the basic structure parameters?including the doping concentration and thickness of drift layer,Pbase layer,N-type CS layer,the width of P+shielding region and the thickness of gate oxide?of 1200V SiC TMOS with N-type CS Layer and P+shielding Layer by using the software of TCAD Silvaco.What's more,we tested and analysed the experiment results using the 4-inch SiC epitaxial wafers on the basis of simulation researchs.First,this paper simulated the static characteristics?including the breakdown voltage,the forward current density,the threshold voltage and the maximum electric field in gate oxide when the TMOS broke down?and dynamic characteristics?including switching time and switching energy loss?.And we optimized the structure parameters of the TMOS,such as the doping concentration and thickness of drift layer,Pbase layer,N-type CS layer,the width of P+shielding region and the thickness of gate oxide.And the breakdown voltage of TMOS was 1740V and the maximum electric field in the gate oxide was 2.96MV/cm on the condition of that the doping concentration and thickness of drift layer,Pbase layer,N-type CS layer were 4×10¹⁵cm^-3/12?m,2×10¹⁷cm^-3/0.6?m,1×10¹⁷cm^-3/0.2?m respectively and the thickness of the bottom of gate oxide was 0.2?m.On the premise of guaranteeing the reliability of the gate oxide,we minimized the switching time and switching energy loss.What's more,we tested the reverse breakdown curves of two TMOS?with P+shielding and without P+shielding?.The breakdown voltage of the TMOS with P+shielding and TMOS without P+shielding were 1620V and 820V,respectively.The Pbase region of the TMOS without P+shielding was punched through,causing the breakdown voltage to be smaller than that of TMOS with P+shielding.There was no microgroove formed at the bottom of trench gate.At the same time,a curved transition was formed at the bottom corner of the groove,which weakened the electric field concentration effect at the corner and improved the gate oxide reliability of SiC TMOS.Through the simulations and the experiments of the 1200V SiC TMOS,this paper provided the ex-period technical support and reference for the later design,experiments and fabrications of SiC TMOS.