We propose two novel ways to alleviate the reverse conducting insulated gate bipolar transistor (RC-IGBT) snapback phenomenon by introducing the floating field stop layer with a lightly doped p-floating layer and recess structure at the backside. The floating field stop layer is submerged in the N-drift region and located several micrometers above the P + anode region, which would not degrade the blocking capability but can suppress the snapback phenomenon effectively. When the collector length exceeds 100 µm, the snapback voltage ΔV SB of the floating field stop RC-IGBT with the p-floating layer can be less than 0.5 V. Furthermore, the recess structure at the backside can separate the N + short and P + anode region, which will be beneficial to eliminate the snapback. Finally, an RC-IGBT with a floating buffer layer and recess at the backside is proposed. Compared to the RC-IGBT featuring an oxide trench between the N + short and P + anode, the proposed one has utilized the simple recess structure to replace the costly oxide trench and achieved the identical characteristics simultaneously.

This paper presents a 1200V-class reverse conducting insulated gate bipolar transistor (RC-IGBT) with low switching energy consumption (LE-RC-IGBT). Its structure was designed in accordance with the latest enhanced trench and field stop technology while incorporating an anti-parallel Free Wheeling Diode (FWD) between the adjacent FS-IGBT cells. With the Emitter Shorted Diode (ESD) technology employed in the design of the FWD structure, the FWD and FS-IGBT can be made simultaneously. By using the same trench etching technique of the gate process, oxide trench was formed on the back side of the device to increase the short-circuit resistance between the N + Collector and the P + Collector on the back of the RC-IGBT. The voltage snapback phenomenon of the conventional RC-IGBT was completely eliminated. The electrical characteristics of the RC-IGBT were investigated by using Sentaurus-TCAD. Simulation results show that the switching energy consumption of the proposed LE-RC-IGBT is reduced by approximately 50%compared with the conventional one.

Abstract. To improve the switching characteristics of conventional structure IGBT, a new trench type bidirectional insulated gate bipolar transistor (IGBT) is proposed. The main feature of this structure is introducing a cell in collector of conventional trench IGBT. The new type IGBT reduce both turn-on and turn-off losses because double-gate IGBT can accelerate carrier extraction speed. By building the device simulation DC/AC circuit of dynamic characteristics, the turn-on time is 0.12μs and turn-off time is 5.1ns. Compared with conventional IGBT, the new type IGBT's turn-on and turn-off loss have a great reduce.

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