A novel 4H-SiC IGBT structure with improved trade-off between short circuit capability and on-state voltage drop

A novel IGBT structure with a built-in lateral JFET region is proposed to reduce the saturation current. A low saturation current level for high voltage IGBTs is desirable for strong short circuit capability. The saturation current can be reduced by increasing the cell pitch of the conventional IGBT structure at the sacrifice of increased on-state voltage drop. The proposed structure provides a greatly improved tradeoff between saturation current and forward voltage drop. Furthermore, reduced saturation current in the IGBT limits the reverse recovery current of the freewheeling diode without substantial increase of the turn-on energy loss at reduced di/dt and prevents the snappiness of the diode during reverse recovery. In this paper, the viability of the new structure is demonstrated using 15kV 4H-SiC devices by 2-D simulations. The proposed new structure can also be applied to devices in other materials and other voltage ratings.