Experimental and numerical investigation on MOSFET's failure during reverse recovery of its internal diode

The failure of the power MOSFET during the reverse-recovery of its intrinsi c body-source diode used as a fly-back element in a half-bridge configurati on has been investigated, The experimental Waveforms have been studied base d on the analysis carried out by a mixed device and circuit simulator, Acco rding to the test conditions, it is shown that during the diode reverse rec overy either a carrier current or a displacement current contribute to the activation of the parasitic BJT, which may cause the failure of MOSFET's. A mong the parasitic elements inherent in the MOSFET structure, the capacitan ce associated to the gate oxide and the resistance of the polysilicon gate are shown to play a relevant role in the activation of the parasitic BJT du e to a displacement current. The activation of the BJT due to carrier curre nt, on the other side, is essentially dependent upon the resistances of the distributed base and of the body-source contact.