 by the structure. High current levels and resultant thermal stress present in the latched condition may result in catastrophic damage to the device. Small, localized regions of the device may experience latchup, termed a microlatchup condition. Compromised logic function of the circuitry involved in the latchup condition is probable. Recovery from a semiconductor latchup condition requires reduction of the device voltage to less than the sustaining or holding voltage for the latchup condition. Single Event Snapback (SES) is a regenerative current mode resulting from the presence of the parasitic bipolar transistor within the MOS device structure. Snapback is a reduction in the breakdown voltage of the parasitic transistor caused by the injection of minority carriers from the source. Although typically resulting in less current than latchup occurrence, the loss of proper operation of the transistor will result in compromised function of the circuit involved. 4.2.2 Single Event Burnout and Gate Rupture [Allenspach96] [Johnson96] Single Event Burnout (SEB) is a destructive condition which results in damage to the source-drain region of n-channel power-MOSFET devices. SEB is triggered by the passage of a heavy ion through a double-diffused power-MOSFET structure which is biased in the off condition. Transient current generated within the device turns-on the parasitic bipolar junction transistor; regenerative feedback increases collector current to the onset of second breakdown, resulting in catastrophic device failure. The regenerative current results from avalanche generated hole current in the collector region. P-channel power-MOSFET devices have not exhibited susceptibility to single event burnout, due to the reduced level of avalanche generated current which is necessary to provide regenerative operation. Single Event Gate Rupture (SEGR) is a destructive condition which results in catastrophic damage to the gate insulator in the power MOSFET devices. Both SEB and SEGR result from the passage of a heavy ion, but 