A TIGBT With Floating n-Well Region for High dV/dt Controllability and Low EMI Noise

A trench insulated gate bipolar transistor (TIGBT) with floating n-well (FN) region is proposed. In the off-state, the n-well region, which is pinched off by its adjacent trenches, would almost have no effect on the breakdown voltage. In the turn-on transient, only a few holes could be attracted into the FN region, because it has a high barrier to holes. So the increase of the potential of the FN region is prevented, which suppresses the reverse displacement current that charges the gate capacitance significantly. As a result, the proposed TIGBT shows excellent controllability on the turn-on dV_CE/dt, and hence, the reverse-recovery dV_KA/dt of free-wheeling diode (FWD). The simulation results based on 1.2-kV TIGBT show that, in comparison with the TIGBT with floating P-base, the lower limit of the reverse-recovery dV_KA/dt of FWD can be reduced by 85.7%.