| Wide-bandgap semiconductor silicon carbide(SiC)power devices have unique advantages such as high withstand voltage,high temperature resistance,and low loss,which make them have great application potential in scenarios with high space volume,energy efficiency and reliability requirements.As an important branch of SiC power devices,SiC PiN diodes with simple structure and excellent performance can be used in electronic power systems to improve power density and reduce system power consumption.This thesis takes the 6500V SiC PiN diode as the research object,optimizes the design of the cell and junction terminal structure,completes the chip tape-out experiment based on the domestic silicon carbide device process line,and conducts test analysis and simulation verification of the pulse discharge characteristics of the device.The research content of this thesis mainly includes the following four parts:Firstly,the working principle of SiC PiN diode is summarized,and the cell structure parameters of SiC PiN diode are determined by theoretical calculation combined with TCAD numerical analysis tool,and the influence of carrier lifetime on its forward characteristics is studied.Secondly,based on the withstand voltage theory of field limit ring and junction termination extension,the junction termination structure of SiC PiN diode is designed and optimized,including Multi Zone Modulation Field Limit Ring(MZM-FLR)and ring Rings-assisted Modulation Junction Terminal Extension(RAM-JTE),to study the influence of key parameters of different junction terminal structures on the voltage withstand capability of the device,and to discuss the SiC/Si O2 interface charge and the effects of different terminal extension regions on the withstand voltage and voltage.Influence of dose window,after comparative analysis,RAM-JTE is finally selected as the terminal structure of high-voltage SiC PiN diode.Then,based on the SiC process flow,the layout drawing and tape-out experiment of the 6500V SiC PiN diode were completed.The test results showed that the specific on-resistance Ron,sp of the device at a current density of 100A/cm~2 was 3.8m?·cm~2,and the forward voltage drop was 3.6V;the breakdown voltage is as high as 8105V under 10?A leakage current,and the terminal efficiency is 95%;BFOM(Baliga's Figure of Merits)is17.5 GW/cm~2.A double-pulse circuit was built to test the reverse recovery characteristics of the device.The reverse recovery time was 78.4ns and the softness factor was 2.4.Finally,based on the RLC second-order discharge circuit theory,using the TCAD simulator and building a test platform,the pulse discharge characteristics of the 6500V SiC PiN diode were studied from the perspectives of simulation and experiment.The influence of peak current Ipeak,pulse current rise rate di/dt and pulse rise time tp.With the increase of charging voltage,Ipeak and di/dt increase approximately linearly,and tp does not change significantly;Ipaek and tpboth increase with the increase of capacitance value,while di/dt is not significantly affected by capacitance value;Ipeak and di/dt change with inductance The value increases and decreases,and tp increases slightly with the increase of the inductance value.The single-pulse experiment shows that under the charging voltage of 3000V,the Ipeak that the SiC PiN diode can achieve is 8.8k A,the di/dt is50.3k A/?s,and the tp is 0.14?s.The static parameters of the SiC PiN diode remained unchanged after 3060 repetitive pulses. |
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