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Recent work for the NASA Electronic Parts and Packaging Program Power MOSFET task is presented. The Task technology focus, roadmap, and partners are given. Recent single-event effect test results on commercial, automotive, and radiation hardened trench power MOSFETs are summarized with an emphasis on risk of using commercial and automotive trench-gate power MOSFETs in space applications.
This describes the mechanisms behind the failure of 4H-SiC Power MOSFETs when struck by a heavy ion. The modeled device is designed to simulate a commercially available 1200 V power MOSFET and the ion simulated is a silver ion with a Linear Energy Transfer of 46 MeV-cm2/mg commonly used in single event effect (SEE) testing. The device is shown in simulation to fail near 500 V, which is in close agreement to experiments. These simulations go to show that the failure of SiC MOSFET occurs near the interface between the epi and substrate layers due to the rapid increase of the electric field in that region and destruction of the device from impact ionization. From this, two designs were proposed and investigated that would help to mitigate the electric field in these regions and improve the device's tolerance to single-event burnout (SEB). The new designs increased the voltage at which SEB occurs from 500 V to over 900 V and increased the Ron,sp by only 5%.
Several newly available Hi-Rel total dose hardened power MOSFETs manufactured by Fuji Electric Device Technology Co. Ltd (FDT) in conjunction with the Japan Aerospace Exploration Agency (JAXA) were tested for single-event gate rupture (SEGR) and single-event burnout (SEB). The safe-operating area (SOA) of the 2SK4217 (a 100 V rated device), 2SK4152 (130 V), 2SK4155 (200 V), and the 2SK4158 (250 V) were tested with silver (Ag) and xenon (Xe) ions having incident LETs of 42.2 and 53.1 MeV cm2/mg, respectively. Test results show these devices are comparable to currently available total dose hardened technology.
We compare the failure mechanism and performance of a silicon carbide (SiC) semi-superjunction (semi-SJ) power DMOSFET against pure SJ and conventional DMOSFET when struck by a single heavy ion. The Single-Event Burnout (SEB) failure mechanism was identified as the thermal runaway from second breakdown resulting in mesoplasma formation. The semi-SJ design shifts the mesoplasma location from the drift/substrate interface seen in the control device structures to a location along the center of the P-pillar and closer towards the DMOSFET surface, thus significantly improving the SEB threshold voltage. The SEB threshold voltage varies with pillar width and ratio of pillar thickness to drift layer thickness. A maximum value of SEB threshold voltage is reached when the pillar to drift layer ratio is 0.9 and the pillar width is 2.4 μm. The semi-SJ SEB/breakdown voltage ratio is 100% and 13% higher than the pure SJ and conventional DMOSFET, respectively. Using a new figure of merit (FOM), which accounts for the tradeoff between SEB threshold voltage and on-state performance, we find that the SiC semi-SJ DMOSFET achieves a FOM that is 1.8 and 8 times higher than SJ and conventional DMOSFET, respectively, making the semi-SJ a competitive candidate for radiation hardened applications.
An overview of the NASA NEPP Program Silicon Carbide Power Device subtask is given, including the current task roadmap, partnerships, and future plans. Included are the Agency-wide efforts to promote development of single-event effect hardened SiC power devices for space applications.
Heavy-ion radiation effects knowledge across SiC power devices is examined and insights for more rugged designs and appropriate test methods geared toward space applications are extracted. The conclusions drawn are supported by recent publicly reported heavy-ion test results of a modified SiC MOSFET design.
Silicon carbide power device technology has the potential to enable a new generation of aerospace power systems that demand high efficiency, rapid switching, and reduced mass and volume in order to expand space-based capabilities. For this potential to be realized, SiC devices must be capable of withstanding the harsh space radiation environment. Commercial SiC components exhibit high tolerance to total ionizing dose but to date, have not performed well under exposure to heavy ion radiation representative of the on-orbit galactic cosmic rays. Insertion of SiC power device technology into space applications to achieve breakthrough performance gains will require intentional development of components hardened to the effects of these highly-energetic heavy ions. This work presents heavy-ion test data obtained by the authors over the past several years for discrete SiC power MOSFETs, JFETs, and diodes in order to increase the body of knowledge and understanding that will facilitate hardening of this technology to space radiation effects. Specifically, heavy-ion irradiation data taken under different bias, temperature, and ion beam conditions is presented for devices from different manufacturers, and the emerging patterns discussed.
The transport, energy loss, and charge production of heavy ions in the sensitive regions of IRF 150 power MOSFETs are described. The dependence and variation of transport parameters with ion type and energy relative to the requirements for single event burnout in this part type are discussed. Test data taken with this power MOSFET are used together with analyses by means of a computer code of the ion energy loss and charge production in the device to establish criteria for burnout and parameters for space predictions. These parameters are then used in an application to predict burnout rates in a geostationary orbit for power converters operating in a dynamic mode. Comparisons of rates for different geometries in simulating SEU (single event upset) sensitive volumes are presented.
1A power MOSFET demonstrated destructive Single-Event Effect (SEE) during ion irradiation in a switching circuit. Further investigation showed that the inductive load causing a spike in the drain-to-source voltage (VDS) that exceeded the manufacturer’s rating for several nanoseconds was enough to allow SEB. These results indicate that SEB may occur in a very short window and flyback is critical for disciplined power supply design.