Research Of Novel High Speed And High Voltage FS-IGBT Device Structure

The development and basic working principle of insulated gate bipolar transistor(IGBT) is briefly introduced. The progress and the state of art in optimizing the forward drop and turn off loss trade-off relationship is comprehensively summarized. From the point of device structure, three novel Field Stop(FS) IGBT structures are proposed. All of the structures have better trade-off relationships and much higher breakdown voltage compared to the conventional counterpart.Trench shorted anode FS-IGBT(TSA-FS-IGBT): anode trench oxide filled with poly silicon is introduced at the anode and the shorted structure is formed. The shorted anode structure obviously lower the turn off time. Supported by the MEDICI simulation and device theory, trench oxide length and thickness which influence TSA-FS-IGBT’s blocking, on-state and turn off performances are profoundly discussed. As simulated results show, the blocking voltage of TSA-FS-IGBT is 257V(approximately equals to 19.5%) higher than the conventional FS-IGBT. Better trade-off relationships are obtained without any side effects such as snapback.Anode buried oxide FS-IGBT(ABO-FS-IGBT): based on the TSA-FS-IGBT, a thin oxide layer is presented in ABO-FS-IGBT. An accumulation layer can be incorporated which significantly improves the breakdown voltage. The influences on blocking, on-state(including Snapback,saturation and temperature characteristics, current uniformity) and turn off characteristics of ABO-FS-IGBT including oxide thickness and length are analyzed in detail. As simulated results show, the optimized blocking voltage of ABO-FS-IGBT is 1551V(17.9% higher than conventional one). The breakdown voltage is slightly lower than the TSA-FS-IGBT while better trade-off relationships are better.Floating P-type layer FS-IGBT(FPL-FS-IGBT): a floating P-type layer is introduced in FPL-FS-IGBT, which obviously simplify the manufacture process compared with new structures mentioned above. The complicated oxide formation at the back side could be replaced by ion implantation. Besides, FPL-FS-IGBT has similar performances just as structures mentioned above. By considering the blocking, on-state and turn off energy, the length, concentration and thickness of P-layer that influence performances of FPL-FS-IGBT are discussed by combining the simulated results and device theory. What’s more, the effect of NPN transistor at anode on the turn off time is analyzed qualitatively. The blocking voltage of FPL-FS-IGBT is 182V(approximately equals to 14%) higher than conventional FS-IGBT and has better trade-off relationships.