Simulation and Optimization of 4H-SiC LDMOS Devices with Field Limiting Ring Structure

Field Limiting Ring (FLR) termination structures are widely used in semiconductor power devices due to their significant improvement in breakdown voltage. A simulation model of 4H-SiC LDMOS with an FLR structure was established using numerical simulation software. The effects of the number of FLRs and the doping concentration of FLRs on the breakdown characteristics and transfer characteristics were simulated. The surface electric field at device breakdown was extracted and analyzed in terms of the uniformity of surface electric field distribution and the peak electric field. The simulation results show that with the increase in the number of FLRs, the breakdown voltage of the device increases. However, when the FLRs are too close to the drain, the breakdown voltage decreases. Additionally, as the doping concentration of the FLRs increases, the breakdown voltage first increases and then decreases.