Design and optimization of variable lateral doping termination for a 650 V IGBT
Breakdown voltage(BV)is one of the most important parameters of IGBT(Insulated Gate Bipolar Transistor)devices,which can be affected by planar process of PN junction diffusion terminals,interface charges,and different coagulation coefficients in Si and SiO2.And the design of the chip terminal structure is one of the important factors affecting the withstand voltage capability.However,improvement of BV is largely restricted by the curvature radius of the depletion region boundary in the terminal area.Here edge termination technology can was used to reduce the curvature effect and increase the BV.This article used Sentaurus TCAD computer simulation software and adopted Variable Lateral Doping(VLD)technology to design a 650 V IGBT power device terminal,where partial silicon was etched away in the VLD region by using mask technique to form a shallow concave structure.The simulation results show that this structure achieves a withstand voltage of 897 V with a terminal length of 256 μm,which is 19.42%less than the field limiting ring terminal structure at the same level of withstand voltage.The maximum surface electric field strength is 1.73×105 V/cm,which is less than the critical breakdown electric field strength of silicon(2.5×105 V/cm).The BV can be increased while greatly reducing the chip area and improving the withstand voltage of the device's main junction.In addition,the fabrication process is not affected,and it is compatible with traditional manufacturing processes for devices.
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