The Study Of The Structure And Electrical Characteristics Of SiC Power Diode

With the development of semiconductor technology and integrated circuit manufacturing technology, it has put forward new requirements for power semiconductor devices, such as low forward voltage drop, low reverse recovery time, low power loss, high frequency and high temperature.etc. Silicon, as the current widely used material for semiconductor devices, has achieved the physical properties limits. Therefore the research of wide bandgap semiconductor devices has become an inevitable trend. Silicon carbide (SiC) as a new generation of semiconductor material with wide band gap, high breakdown field, high thermal conductivity, good thermal stability characteristics, is the focus of research on power electronic devices.SiC SBD has the advantages of zero reverse recovery, fast switching speed and low power consumption; SiC PiN diode has the characteristics of low reverse leakage current, high breakdown voltage. In this paper, we designed the SiC JBS structure, by combining the SiC SBD and the SiC PiN diode, and then investigated the electrical properties of SiC JBS. The main contents are as follows:First, the working principle of JBS diode and the cell structure. We studied the SiC JBS diode’s forward characteristics and reverse blocking mechanism. The impact factor of reverse breakdown voltage(VB):the epitaxial layer thickness, the breakdown field strength. We analyzed of the composition of resistance(Ron), including channel resistance, diffusion resistance, drift resistance, substrate resistance and contact resistance.Second, we designed and optimized the 3300V SiC JBS diodes’structure. The effect of the space(S) between adjacent P+regions on the electrical characteristics of JBS diode is studied. The forward Ⅰ-Ⅴ characteristic curve and reverse leakage current of the device are analyzed, and the bigger the space(S) is, the bigger the reverse leakage current is. The effect of the width(W) and doping concentration of P+regions on the electrical characteristics of JBS diode is studied. Analyzed the Ⅰ-Ⅴ curve and achieved the width value(W,2.6μm) of the optimal resistance(Ron). The reverse blocking characteristics of the device are analyzed, and it is concluded that the P+doping concentration has a direct effect on the Ron, but it has no relation with VB, which is consistent with the theoretical formula. And the optimized P+region doping concentration is 5r1018cm-3 for the 3300V SiC JBS diode. The effect of the doping concentration and thickness of the epitaxial layer on the reverse breakdown voltage of the device was studied, and obtained the optimum epitaxial layer thickness of the SiC JBS 3300V diode.