Surface Buffer IGBT for High Total Performance

A new structure in trench-gate insulated gate bipolar transistor (IGBT) design is proposed and analyzed not only for power loss reduction but also for long-term stability and suppressing electromagnetic interference (EMI) noise using a device simulation. Although turn-off loss and ON-state voltage drop Vce(sat) are improved by injection enhancement(IE) effect, IE effect causes dynamic avalanche that limits turn-off loss reduction and degrades long-term stability by the charge trap at the trench gate oxide interface. In addition, hole current around the gate induces EMI noise due to the negative gate capacitance. This article shows that the proposed surface buffer (SB) IGBT suppresses dynamic avalanche and negative gate capacitance maintaining low power loss by covering the trench gate bottom and hole evacuation from the pMOS channel.