A new composite gate structure IEGT device design

Based on traditional planar gate IEGT device, a new composite gate structure IEGT device was designed. The device is compatible with electron injection enhancement and carriers storage technology. The longitudinally extending trench gate of the device increases the effective gate length without increasing gate area, and carrier concentration inside the N-drift region is increased. The existence of the trench can reduce the electric field of the side of the P-type base, improve the breakdown voltage falling because of high concentration of the N-type barrier layer, and increase surface carrier concentration to reduce device saturation voltage drop. The device has two different thicknesses of the gate oxide, the gate oxide near the p-type base region adopts a thin gate oxide to maintain the device's normal threshold voltage, and the rest of gate region uses thick gate oxide to reduce the device capacitance which is useful to reduce the switching loss.