Abstract: The dynamic robustness of FS-IGBT with multiple proton injection buffers (MPI) is changed compared with the same type of devices which has traditional phosphorus injection buffers. By studying the short-circuit characteristics of FS-IGBT with MPI buffer layer, it is found that the higher the number of peaks in MPI buffer layer, the stronger the resistance to short-circuit thermal failure. However, too many peaks may cause the gate voltage oscillation of IGBT during short-circuit, resulting in device failure. This is related to Kirk effect of IGBT under large short circuit current. Kirk effect results in the reduction of the electric field under the IGBT gate electrode and the decrease of the electron velocity, and then the accumulated electrons under the gate electrode cause the change of the gate input capacitance, leading to gate voltage oscillation. In addition, it is found that the hydrogen-related donors (HDs) concentration of MPI buffer layer peak is not only related to the injection dose and activation temperature, but also related to the injection times. The more the injection times, the higher the concentration of HDs caused by radiation damage. The turn-off robustness of IGBTs with different MPI buffer structures is also studied.