This invention belongs to the field of power
semiconductor technology and relates to SOI LIGBTs with integrated NMOS and multiple floating field plates. This invention introduces a double-layer floating field plate above the drift region of the SOI LIGBT, utilizing the floating
metal field plate to achieve
adaptive switching of the auxiliary NMOS integrated on the
cathode side. During forward conduction, the lower
anode voltage keeps the second NMOS in a high-resistance state, causing the node
voltage across the parasitic
diode to exceed its built-in potential and turn it on, providing an additional
electron injection source for the drift region and reducing the on-state
voltage drop. During turn-off, the high
anode voltage increases the
gate voltage of the second NMOS through
capacitive coupling of the floating field plate, enabling it to conduct adaptively, providing a low-resistance path for excess holes in the drift region and reducing turn-off losses. In the saturation state, the second NMOS under the high
anode voltage enters a strong inversion state, causing the parasitic
diode to exit the forward bias state,
cutting off the additional
electron injection source, and strictly clamping the saturated anode current at a low level, improving the device's short-circuit withstand capability.