Design And Characteristics Research Of 4H-SiC PiN Diodes

PiN power diode which is made of the third generation wide bandgap semiconductor silicon carbide(SiC)is coming into prominence owing to its brilliant performance such as high breakdown voltage,fast switching speed and small forward conduction resistance.However,the study of ultra-high voltage SiC power device is still developing in China,and the technology has not refined yet.Under the circumstances,this dissertation has designed an ultra-high voltage SiC PiN diode,computer two dimensional simulation technology is used to optimize its structure.All above is based on domestic experimental level,which is for the purpose of providing useful experience for peer researchers.SiC PiN diode has high research value and broad application prospects due to its small forward conduction resistance,high reverse blocking voltage as well as fast switching speed.This thesis first introduces how a SiC PiN diode working under forward and reverse bias.Besides,based on Silvaco Technology Computer Aided Design(TCAD)software,some important physical models such as mobility model,carrier recombination model and ionization model is explained,laying good foundation for further structure design.Secondly,through literature survey,the design of the key parameters(thickness and concentration of SiC PiN diode's drift region)is done.In order to achieve a breakdown voltage above 10kV,this dissertation has also proposed several termination structure,such as Junction Termination Extension(JTE),Field Limiting Ring(FLR)and Space-Modulated Junction Termination Extension(SM-JTE).Furthermore,how those key parameters affect the breakdown voltage has been studied.For better simulation results,the effect of SiO2/SiC interface charges has also been discussed in detail.After rigorous analysis and optimization,a new SM-JTE with wider dose window is proposed.Finally,the experimental research of ultra-high voltage SiC PiN diode is carried out.Based on domestic experimental level,the process flow of the device is developed,the layout was drawn and the tape-out experiment is accomplished.After that,the forward conduction and reverse breakdown characteristics of the device is analyzed by the test.Test result suggest that the anode current of this device is>6A at room temperature,forward voltage drop is 3.6V@100A/cm~2,reverse leakage current is<1A under 10kV,which realizes the key technical indicator of this ultra-high voltage SiC PiN diode.