Impact of Cell Layout and Device Structure on On-Voltage Reduction of 6.5-kV n-Channel SiC IGBTs
A box cell layout and a hole-barrier structure were used to realize low-on-voltage n-channel 4H-SiC IGBTs with 6.5-kV blocking capability. Box cell layout can increase the channel width, leading to reduction of the channel resistance and an enhancement of electron injection from an emitter. Hole-barrier structure, which is a potential barrier for holes to prevent them from flowing out of the emitter, can enhance conductivity modulation. An on-voltage of 3.98 V at a collector current of 100 A/cm2 was achieved from a fabricated SiC IGBTin this study. Since the on-voltage of a SiC IGBT with a conventional structure was 4.81 V at the same collector current, the effect of our new structure was successfully shown to reduce the on-voltage of SiC IGBTs. An estimation of each voltage component involved in the on-voltage was also carried out by utilizing a device simulation, and the estimation shows that a SiC IGBT incorporating a box layout and hole-barrier structure will thus have quite a low drift-layer voltage and an on-voltage close to the limit determined by the bipolar built-in voltage.
Robert Stahlbush, Philip Neudeck, Anup Bhalla, Robert P. Devaty, Michael Dudley and Aivars Lelis
N. Watanabe et al., "Impact of Cell Layout and Device Structure on On-Voltage Reduction of 6.5-kV n-Channel SiC IGBTs", Materials Science Forum, Vol. 924, pp. 637-640, 2018