Experimental study of the anode injection efficiency reduction of 3.3-kV-class NPT-IGBTs due to backside processes

The anode injection efficiency reduction of 3.3-kV-class non-punch-through insulated-gate bipolar tran- sistors (NPT-IGBTs) due to backside processes is experimentally studied through comparing the forward blocking capabilities of the experiments and the theoretical breakdown model in this paper. Wafer lifetimes are measured by a -PCD method, and well designed NPT-IGBTs with a final wafer thickness of 500 m are fabricated. The test results show higher breakdown voltages than the theoretical breakdown model in which anode injection effi- ciency reduction is not considered. This indicates that anode injection efficiency reduction must be considered in the breakdown model. Furthermore, the parameters related to anode injection efficiency reduction are estimated according to the experimental data.