Design Optimization And Experimental Investigation Of High Voltage Silicon Carbide JBS Diode

Silicon Carbide Junction Barrier controlled Schottkey Diode(SiC JBS) is the power device fabricated on the wide band-gap semiconductor material silicon carbide. Owing to its thermal, chemical and physical stability such as high thermal conductivity, high critical electric field, high electron saturated velocity and other physical properties, SiC is an attractive semiconductor material for power diode. Based on the basic of semiconductor devices, 4H-SiC JBS is investigated by computer numerical simulation, including the optimization of device structures, technology of crucial process and fabrication process of JBS.The cell structure of high voltage 4H-SiC JBS is designed by simulation. The key parameters include width, space and doping profile of P+. Meanwhile, the dependence of the forward and reverse characteristics on the parameter is discussed. Based on the optimized cell structure, breakdown voltages of 6760 V and 6475 V are achieved by the design of linearly graded FLR and etching of multi-zone JTE, and the termination efficiency are 94% and 91%, respectively. Etched JTE can modulates the dose of charges in the termination, contributing to a more uniform variation of electric field, and the termination area of 210 μm etched JTE is 156.8μm smaller than that of linearly graded FLR with 35 rings. However, the breakdown voltage of etched JTE is sensitive to the depth of etching. Taking into consideration that p ions can be offset by n ions, a novel structure called inverse impurity doping JTE is proposed because the dose and energy of ion implantation can be controlled accurately, which realized the breakdown voltages of 6260 V and termination efficiency of 88%.According to the optimization of diode structure and actual process conditions, the technology of etching and schottkey contact are studied. A good morphological surface of groove can be got by regulating the power, pressure and atmosphere. And we obtain good characteristics of SiC/Ni schottkey contact due to proper temperature and time of post deposition annealing. At last, the device layout is designed and the experiment is carried out.