Channel Density Design Guidelines for the Transient Characteristics of SiC Trench Gate MOSFETs

Channel density design guidelines for SiC trench-gate MOSFETs with low switching loss, and high short-circuit and avalanche capabilities were proposed. The cell and grounding region pitches were used as parameters to control the channel density to investigate the parameter dependence of each transient property. The results suggest a clear difference in the dependence of switching loss reduction and short-circuit/avalanche capability increase on these parameters; however, the extents of dependence of specific on-resistance on the controlling parameters were comparable. The reduction in the grounding region pitch contributed to faster charging of the parasitic drain-source capacitance, which was effective in improving transient characteristics, such as dV/dt at turn-off, and saturation current at short-circuit. Furthermore, a reduction in this distance increased the area-flowing avalanche current and hence, an increase in the avalanche energy. The influence of the two design parameters in effectively improving the trade-off between each transient characteristic and the specific on-resistance was summarized.