Design And Simulation Of SiC Super-junction SBD

In this thesis, the device structure design and characteristics simulation of high-power SiC SBD devices are carried out using two-dimensional device simulator MEDICI. In the research, To reduce the device on-resistance (Ron) which is the main objective, the forward and blocking characteristics of 4H-SiC Schottky barrier diode are analyzed, and the structural parameters are optimized, as well as some new device structure and theory introduced, which leads to a minimized the specific on resistance (Ron, sp) and a maximum output power under a determined breakdown voltage.The conventional structure SiC SBD, the application of super-junction (SJ) theory in the design of drift layer, semi-SJ structure and the effects of charge imbalance in the SJ structure are studied by numerical simulation. In the optimization of the conventional structure, it is found that a lower on-resistance can be got in the punch through (PT) design of the drift region. In order to effectively improve the trade-off of high-blocking capability and get lower on-resistance, a new theory——superjunction (SJ) is introduced into the drift layer design. The resistance reduced by more than 60% at the same blocking voltage level in the SJ SBD, which using charge compensation principle. Taking the manufacter of SJ into account, to ensure accurate charge balance is difficult, the analysis of the charge imbalance is very important. A novel asymmetric superjunction (ASJ) structure is proposed, compared with the conventional SJ, it can not only reduce the on-resistance, but also effectively prevent the breakdown voltage drop which caused by charge imbalance. The design demand can be satisfied and process reduced, using a Semi-SJ structure, which combines the advantages of SJ and PT. The mathematical models of VB and Ron,sp are established. The detailed analysis of the manufacture of SJ is also analyzed.