| The progress of modern industry increasingly requires the support of hightemperature,high-frequency,and high-power devices.Due to the limitations of the material itself,Si has certain limitations in the actual application process.However,the third-generation semiconductor materials represented by SiC,in contrast,because the material itself has the characteristics of wide bandgap,high temperature and high pressure resistance,it can better adapt to various working conditions,and then can provide obvious performance improvements for different applications and systems,and has a great The market potential of China is the focus of attention of various countries.Among various SiC power semiconductor devices,SiC MOSFET,as a typical representative,has the characteristics of high withstand voltage,high current flow,low loss and high temperature resistance,and has become an important choice for new power electronic devices.Although SiC MOSFET has certain advantages compared with other traditional power devices,there are still many problems to be solved in the actual application process,such as the constraint relationship between on-resistance and breakdown voltage,which greatly limits the breakdown voltage of SiC MOSFET Level and current density,if you want to increase the withstand voltage of the device,the onresistance will increase,which will reduce the current density of the device and affect the working efficiency of the device.Firstly,a comparative study was made on the research situation of silicon carbide MOSFET devices at home and abroad,and then the working principle of silicon carbide MOSFET devices was studied,and the switching process and basic characteristics of the device were analyzed in combination with the research content,based on the theoretical model related to the switching characteristics of the device,such as blocking model,gate control model,resistance model,capacitance model,etc.,have studied the electrical parameters and structural parameters that affect the switching characteristics of devices.Carried out a simulation study on the cell characteristics of high current density 1200V SiC MOSFET,and analyzed the structural parameters such as epitaxial layer parameters,Pwell region doping concentration,gate oxide layer thickness,JFET region parameters and channel length for SiC MOSFET by establishing a simulation model.Influenced by the characteristics of the characteristics,the optimal structural parameters were obtained,the cell structure was optimized,a 1200V SiC MOSFET structure with high current density was designed,and the terminal structure was simulated to determine the optimal ring spacing and the number of rings,and the slow-change Ring pitch field limiting ring structure.This paper innovatively proposes a SiC MOSFET device structure that integrates Schottky diodes in the source region of the cell,and performs cell characteristic simulation on the proposed structure.Compared with the planar SiC MOSFET designed above,it is found that the designed The cell structure has almost no effect on the original static characteristics of the MOSFET,and at the same time improves the reverse recovery characteristics.The diode turn-on inflection point voltage of the third quadrant characteristic curve is reduced from 3 V to 1.5 V.Finally,this paper combined the existing process conditions to carry out two batches of tape-out experiments,and tested the dynamic and static parameters of the device respectively.The results showed that the parameters of the prepared chip met the expected requirements,and the specific on-resistance was less than 10mΩ.cm2,verified the rationality of the designed structure and simulation software,and then started from the reliability verification test of SiC MOSFET devices,strengthened the ability of material,process and process quality control,and improved reliability.High temperature reverse bias test,intermittent Life test and temperature cycle test have verified that all 20 SiC MOSFET devices have not failed. |
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