The Failure Mechanism of the Guard-Rings in Two Different Power Domains during the Latch-Up Test

The failure mechanism of latch-up in two different power domains for the high voltage (HV) output driver under the positive trigger current latch-up test is investigated. From the T-CAD, why the guard-rings (GRs) in two different power domains are damaged is found. It is caused by the conductivity modulation effect as the region between two power domains is triggered into the latch-up state. So, this region becomes an intrinsic region (resistor) to induce power short to power, resulting in the GR damage.