Accelerated Tests on Si and SiC Power Transistors with Thermal, Fast and Ultra-Fast Neutrons

Abstract

Neutron test campaigns on silicon (Si) and silicon carbide (SiC) power MOSFETs and IGBTs were conducted at the TRIGA (Training, Research, Isotopes, General Atomics) Mark II (Pavia, Italy) nuclear reactor and ChipIr-ISIS Neutron and Muon Source (Didcot, U.K.) facility. About 2000 power transistors made by STMicroelectronics were tested in all the experiments. Tests with thermal and fast neutrons (up to about 10 MeV) at the TRIGA Mark II reactor showed that single-event burnout (SEB) failures only occurred at voltages close to the rated drain-source voltage. Thermal neutrons did not induce SEB, nor degradation in the electrical parameters of the devices. SEB failures during testing at ChipIr with ultra-fast neutrons (1-800 MeV) were evaluated in terms of failure in time (FIT) versus derating voltage curves according to the JEP151 procedure of the Joint Electron Device Engineering Council (JEDEC). These curves, even if scaled with die size and avalanche voltage, were strongly linked to the technological processes of the devices, although a common trend was observed that highlighted commonalities among the failures of different types of MOSFETs. In both experiments, we observed only SEB failures without single-event gate rupture (SEGR) during the tests. None of the power devices that survived the neutron tests were degraded in their electrical performances. A study of the worst-case bias condition (gate and/or drain) during irradiation was performed.

Investigation of the Impact of Neutron Irradiation on SiC Power MOSFETs Lifetime by Reliability Tests

“…All test vehicles (see Table 1 of [ 8 ] ) were irradiated with neutrons at the ChipIr beamline of the ISIS spallation source at the Rutherford Appleton Laboratory, UK facility. These devices were irradiated in different neutron test campaigns preformed by STMicroelectronics and Airbus and according to the JEDEC JEP151 procedure [ 18 ].…”

“…These devices were irradiated in different neutron test campaigns preformed by STMicroelectronics and Airbus and according to the JEDEC JEP151 procedure [ 18 ]. Some results of the accelarated neutron testing by ST are reported in [ 8 ]. These devices were tested to determine the sea-level failure rate at different drain bias and with zero gate-source voltage by using a neutron tester system developed by ST.…”

“…Some authors report also gate damage in power MOSFET’s after neutron exposure, which for some devices results in a complete gate rupture (SEGR) [ 7 ]. Failure mechanisms in high-voltage power semiconductor devices due to the cosmic radiation limit the maximum operating DC blocking voltage, thus accelerated terrestrial neutron irradiations were usually performed on commercial power MOSFETs to estimate the failure in time (FIT) (1 FIT = 1 failure/billion hours) at different de-rated values of their maximum rated blocking voltages [ 4 , 5 , 8 , 9 , 10 , 11 ]. The atmospheric neutron flux at sea level is 13 (n/cm h) for neutron energies higher than 10 MeV and it increases with the altitude with a peak at approximately 20-km.…”

“…The aim of this work is to investigate not only degradation phenomena but also the impact on the reliability of the devices of SiC power MOSFETs do not fail during a neutron irradiation run. In [ 8 ] we performed an electrical characterization to evaluate the gate-oxide integrity on Si and SiC power devices which survive the neutron tests. In this work we extend this investigation by means a more complete electrical characterization of all survived test vehicles irradiated at Chip-Ir facility during many neutron test campaigns, which include also those reported in [ 8 ].…”

“…In [ 8 ] we performed an electrical characterization to evaluate the gate-oxide integrity on Si and SiC power devices which survive the neutron tests. In this work we extend this investigation by means a more complete electrical characterization of all survived test vehicles irradiated at Chip-Ir facility during many neutron test campaigns, which include also those reported in [ 8 ]. These neutron test campaigns were performed to increase the statistics and to evaluate neutron performance at avionic altitude, by using different neutron tester systems as well.…”