Investigation of IGBT turn-on failure under high applied voltage operation
In this paper, a new failure mode of punch-through type insulated gate bipolar transistors (PT-IGBTs) at short circuit condition under high voltage operation has been presented. After turning on the IGBTs, this failure mode is characterized as an abrupt destruction mode that takes place several microseconds later under higher collector voltage short circuit conditions. The destruction mechanism of the IGBTs has been investigated using a 2-D and a 3-D device simulation. It is found that the hole-current caused by dynamic avalanche generation at the peripheral region of the device leads to concentrate on a certain point such as the emitter contact edge of the active cells. Subsequently the IGBTs plunge into destruction. This hole-current aggregation depends on geometrical structure of the active cells close to the device peripherals where a parasitic PMOS is formed. The generated hole-current path is varied by the gate voltage and this effect results in degradation of the short circuit capabilities depending on the gate voltages. This model has been evaluated experimentally by making punch-through type IGBTs with a rating current of 200A and the IGBTs have shown enough short circuit capabilities. These devices have successfully been adopted as power devices of invertors for a new hybrid vehicle.