Failure Analysis of Heavy Ion-Irradiated Schottky Diodes

Abstract

When a Schottky diode experiences enough degradation to cause the post-irradiation electrical parameter measurements to be out of specification, failure analysis appears to show that the damage occurs solely at the Schottky metal/silicon interface. This is in contrast to when a diode fails catastrophically. In that case, the event appears to also begin at the metal/silicon junction, however, the event generates such extreme heat that the materials become molten. A filament is then created that displaces the metal into the bulk silicon and can also displace silicon to the surface of the diode. This filament shorts the anode (bulk silicon) to the cathode (Schottky barrier metal) and the current is only limited by the power supply.To avoid these radiation responses in which the diode is operating outside of the manufacturer's specifications, a reverse voltage derating of 50% is recommended when testing will not be conducted. If testing will be conducted on the flight diodes under the application-specific bias conditions, then a derating similar to power MOSFETs is recommended, in which the maximum reverse voltage that may be used is 75% of the last passing voltage.In this work, we use high-and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

Single-Event Burnout of SiC Junction Barrier Schottky Diode High-Voltage Power Devices

“…The 500 V temperature peak does not quite reach 3100 K (again these temperatures are conservative), but this supports the case that melting of the silicon carbide would be observed around 500 V, resulting in a burnout event. Recent failure analysis results on silicon Schottky diodes indicates that devices that display degraded leakage current after exposure to heavy ions are found to have small regions of fused silicon under the Schottky junction, which may support the hypothesis that a phase change or eutectic interaction is causing the degraded behavior in silicon carbide JBS diodes [28].…”

Investigation of Electrically Active Defects in SiC Power Diodes Caused by Heavy Ion Irradiation

“…In fact, the current commercially available technologies of SiC power devices are sensitive to radiation which can increase the risk of single event effects (SEEs). Consequently, radiation tests on SiC Schottky power diodes are performed to study the susceptibility to SEE, such as single event leakage current degradation (SELC) and single event burnout (SEB) [3][4][5][6][7][8][9][10].…”

“…Degradation or SELC is observed in Region II, characterised by a permanent increase of leakage current with increasing heavy ion fluence. Although this increase is non-catastrophic, the device performance may become limited and compromise the long-term reliability of the device [8]. This mechanism of degradation was suggested to be the same as observed in SiC MOSFETs [9] and to be associated with the creation of extended defects in the SiC crystal (i.e., stacking faults) [10][11].…”