The Structure Design And Optimization Of 4H-SiC JBS

As a representative of wide bandgap semiconductor materials,silicon carbide has a large band gap(Eg> 2.3eV),high critical breakdown electric field,large carrier saturation velocity,high thermal conductivity and other fine features.Silicon carbide(SiC)has become an ideal semiconductor material for the production of anti-radiation,high-frequency,high temperature,and low power consumption and high power electronic devices.The JBS(junction barrier schottky)rectifier offers Schottky-like on-state and fast switching characteristics,while the off-state characteristics have a low leakage current similar to that of the PiN rectifier.The 4H-SiC JBS diode combines the advantages of the electrical properties of silicon carbide materials and structural advantages of JBS diodes,having an excellent electrical characteristics compared with common JBS,being widely used in high-frequency,high-voltage and high-power field,having been the main development trend of the power diode.The main work of this paper is structure design and optimization of high-voltage 4H-SiC JBS.The investigation and optimization of the performance simulation are carried out in the device simulation software ATLAS.Based on the simulation,analysis and research of the on-state and off-state of 4H-SiC JBS,by embedding an oxide layer in the active area and using the heterojunction to replace the Schottky contact,we can improve the forward voltage drop,reduce the on-resistance and increase the blocking voltage of the device.Two new structure were proposed:(1)junction barrier shottky diode with embedded sidewall oxide layer(ESO-JBS),with an oxide layer embedded in the active region(P + region)in the common JBS;(2)heterojunction junction barrier diode(HJBD),using the heterojunction to replace the Schottky contact of the traditional JBS device.The ESO-JBS device can increase the effective area of the Schottky contact,thus effectively reducing the forward voltage drop and on-resistance of the device without sacrificing the blocking characteristic.The HJBD device can effectively increasing the blocking voltage with a forward performance similar to common JBS or improve the forward performance with a blocking characteristic similar to common JBS.Through theoretical analysis and estimation,and the simulation and parameter optimization work with the ATLAS simulation tools,we have achieved two devices,ESO-JBS and HJBD which have the blocking voltage of 1400 V and 1085 V,respectively.