Failure mechanism of high-voltage isolated lateral diffused NMOS under high-current events

In this study, the mechanism of the effect of a high-voltage (HV) NWell guardring (NW-GR) on the electrostatic discharge (ESD) robustness of the HV isolated lateral diffused NMOS (HV ISO-LDNMOS) is investigated. The device fails on low-voltage ESD zapping events when the HVNW-GR is connected to the drain, whereas the device passes these events once it is floated.