Single Event Burnout Research Articles

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

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.

Research of single-event burnout and hardened GaN MISFET with embedded PN junction

This paper describes a single-event burnout (SEB) simulation for a conventional GaN MISFET field plate (FPC-MISFET) and a MISFET with an embedded pn junction (EJ-MISFET). The SEB triggering mechanism is affected by impact ionization. The electrons, which are induced by heavy ion exposure, can rapidly move to the drain, which leads to strong impact ionization around the drain. Compared to the FPC-MISFET, both the peak electric field and the impact ionization around the drain are reduced in the GaN MISFET with the embedded pn junction. The proposed EJ-MISFET also shows improved SEB performance. For a heavy ion, with a linear energy transfer (LET) of 0.6 pC/μm (hitting the devices) vertically, the SEB threshold voltages for the FPC-MISFET and EJ-MISFET are 520 and 760 V, respectively.

Impact of Electrical Stress and Neutron Irradiation on Reliability of Silicon Carbide Power MOSFET

The combined effects of electrical stress and neutron irradiation of the last generation of commercial discrete silicon carbide power MOSFETs are studied. The single-event burnout (SEB) sensitivity during neutron irradiation is analyzed for unstressed and electrically stressed devices. For surviving devices, a comprehensive study of the breakdown voltage degradation is performed by coupling the electrical stress and irradiation effects. In addition, mutual influences between electrical stress and radiative constraints are investigated through TCAD modeling.

Effects of Total-Ionizing-Dose Irradiation on Single-Event Burnout for Commercial Enhancement-Mode AlGaN/GaN High-Electron Mobility Transistors* *Supported by the National Natural Science Foundation of China under Grant Nos. U1532261, U1630141, and 61534008, and the West Light Foundation of Chinese Academy of Sciences under Grant No. 2018-XBQNXZ-B-003.

We investigate the synergism effect of total ionizing dose (TID) on single-event burnout (SEB) for commercial enhancement-mode AlGaN/GaN high-electron mobility transistors. Our experimental results show that the slight degradation of devices caused by gamma rays can affect the stability of the devices during the impact of high energy particles. During heavy ion irradiation, the safe working values of drain voltage are significantly reduced for devices which have already been irradiated by 60 Co gamma rays before. This could be attributed to more charges trapped caused by 60 Co gamma rays, which make GaN devices more vulnerable to SEB. Moreover, the electrical parameters of GaN devices after 60 Co gamma and heavy-ion irradiations are presented, such as the output characteristic curve, effective threshold voltages, and leakage current of drain. These results demonstrate that the synergistic effect of TID on SEB for GaN power devices does in fact exist.

Single event burnout hardening of trench shielded power UMOSFET using High-κ dielectrics

This study proposes the High-κ dielectric Trench Shielded power UMOSFET (HK TS-UMOSFET) to be assessed using the two-dimensional numerical simulations. The simulations are employed to evaluate HK TS-UMOSFETs susceptibility to single-event burnout (SEB) mechanism. Based on the findings, the influence of alternative high permittivity gate dielectrics to silicon dioxide (SiO2) in TS-UMOSFET was discussed. Furthermore, in order to improve the performance of the device, its electrical behaviour was simulated with several high-κ dielectrics including Al2O3, Si3N4 and Aluminium Nitride (AlN). When heavy ions strike the sensitive areas of the device, the electric field distribution and SEB threshold values were extracted. Based on the values yielded, (AlN) was identified as a promising high-κ material to achieve SEB-hardened TS-UMOSFET compared to the other high-κ dielectrics. In conclusion, with (AlN), the HK TS-UMOSFET offers a high SEB tolerance and improved electrical characteristics.

Inclusion of Radiation Environment Variability for Reliability Estimates for SiC Power MOSFETs

Variability of the solar energetic particle environment is investigated for single-event burnout (SEB) reliability of silicon carbide power metal-oxide-semiconductor field-effect transistors. A probabilistic assessment of failure evaluates the benefits of derating voltage, shielding, and mission length. The Prediction of Solar particle Yields for Characterizing Integrating Circuits code is used to calculate a cumulative density function for the fluence of the environment. The lethal ion method is then used to determine what proportion of the environment will cause SEB. The operating voltage determines the lowest linear energy transfer (LET) particle that will cause SEB, and that should be included in the environment distribution. The shielding and mission length also determines the final environment distribution of the mission fluence. When the critical LET for a device is relatively low for the expected mission environment, the method in this article can calculate the probability of failure from a destructive event. The calculated probability of failure enables the consideration of part use outside the safe operating area, especially when derating the operating voltage would eliminate the technology advantage of the part.

An SEB Hardened AlGaN/GaN HEMT With Barrier Interlayer

A new single event burnout (SEB) hardened AlGaN/GaN structure with a thin barrier interlayer (IL) is presented in this work. The proposed hardened structure is compared with the simulation results of the conventional structure. The comparative analysis demonstrates that the IL lifts the conduction band energy in buffer layer and a new quantum well is formed. The quantum well limits the electrons induced by heavy ion below the second channel into the first channel. Thus, better SEB performance is achieved compared with the conventional structure. Moreover, the breakdown characteristic of the new structure is significantly improved, while the output characteristic is slightly reduced. Under the condition that the two structures are irradiated vertically by heavy ion having the linear energy transfer (LET) value of 0.6 pC/ $\mu \text{m}$ , the SEB threshold voltage of the conventional structure is 280 V, while the hardened structure can achieve 375 V.

Ion-Induced Energy Pulse Mechanism for Single-Event Burnout in High-Voltage SiC Power MOSFETs and Junction Barrier Schottky Diodes

Heavy-ion data suggest that a common mechanism is responsible for single-event burnout (SEB) in 1200-V power MOSFETs and junction barrier Schottky (JBS) diodes. Similarly, heavy-ion data suggest a common mechanism is also responsible for leakage current degradation in both devices. This mechanism, based on ion-induced, highly localized energy pulses, is demonstrated in simulations and shown to be capable of causing degradation and SEB for both the MOSFETs and JBS diodes.

Single-Event Effects in SiC Double-Trench MOSFETs

Single-event effects (SEEs) in a 650-V state-of-the-art SiC double-trench MOSFET (DT-MOS) are investigated using the Sentaurus TCAD tools. The safe operation areas (SOAs) for single-event burnout (SEB) and single-event gate rupture (SEGR) are extracted when heavy ions with different linear energy transfer (LET) impact the sensitive regions of the device. The results show that the radiation performance of the SiC DT-MOS is poor because of the very low threshold voltages of failures at a high LET range. Moreover, hardening measures, such as introducing a buffer layer and adjusting the mesa width, are discussed to assess their versatility. It is demonstrated that in contrast, the SEGR problem is more severe due to the intrinsic properties of SiC devices. Therefore, it becomes a crucial issue to find ways more suitable for the SiC DT-MOS to avoid gate oxide pre-breakdown, before they could serve as a replacement of Si counterparts in space applications.

Single-Event Burnout Hardness for the 4H-SiC Trench-Gate MOSFETs Based on the Multi-Island Buffer Layer

In this article, the performance and triggering mechanism of the single-event burnout (SEB) of a 4H-SiC trench-gate (TG) MOSFET structure are evaluated by the 2-D numerical simulations. The novel N+ island buffer 4H-SiC TG MOSFET and the conventional TG 4H-SiC MOSFET are analyzed and compared to examine whether an N+ island region introduced in the second buffer can effectively reduce the impact ionization located at the N− drift/N+ buffer junction and improve device tolerance to the SEB. The TCAD simulation results revealed that compared with the conventional structure, which is a simple double-buffer structure, the N+ island buffer-hardened structure changed the burnout threshold voltage, improving the SEB performance significantly. In addition, the results proved that the impact ionization played an important role in the SEB triggering mechanism, significantly affecting the SEB performance of the 4H-SiC TG MOSFET. The performance of the hardened N+ island buffer with a different dopant concentration of N-buffer 2 and a size of N+ island is discussed. The specific burnout threshold voltage at the optimal parameters of the proposed structure is 47% higher than that of the conventional structure.

Gate Damages Induced in SiC Power MOSFETs During Heavy-Ion Irradiation—Part I

Experimental characterization of the damage induced to SiC power MOSFETs by heavy-ion irradiation is presented as a premise to a finite element simulation study aimed at gaining an insight into the physics of damage formation. Thanks to the new experimental setup, which is capable of accurately measuring the time evolution of the gate and drain leakage currents during irradiation, we herein demonstrate that the gate of a SiC power MOSFET is damaged by heavy-ion irradiation at biasing drain voltages lower than 100 V, which is less than 10% of the nominal blocking voltage of the tested devices. The evolution of the gate and drain leakage currents during irradiation is explained considering that localized resistive paths due to damage sites are formed across the gate oxide. The results presented herein indicate the strong sensitivity of SiC power MOSFETs to gate rupture even if the main concern in the literature addressed so far is the rupture of the drain structure due to single-event burnout.

Robustness and reliability review of Si and SiC FET devices for more-electric-aircraft applications

Increased electrification of traditionally hydraulic and pneumatic functions on aircrafts has put power electronics at the heart of modern aviation. Aircraft electrical power systems have traditionally operated at 115 V AC and 28 V DC with a constant speed generator and transformer rectifier units converting jet engine power into electrical power. However, due to the increasing trend towards the More Electric Aircraft (MEA), 270 V DC systems are likely in the future. This calls into question, the power semiconductor device technology that enables the on-board power converters needed for electro-mechanical actuation as well as solid-state circuit breakers for system protection. Silicon IGBTs have been the work-horse of power electronics, but as switching speeds increase due to the need for high frequency operation, the bipolar nature of IGBT tail currents become a limiting factor for improved energy conversion efficiency. A number of unipolar FET technologies, including SiC trench MOSFETs, SiC planar MOSFETs, silicon super-junction MOSFETs and SiC JFETs in cascode with a low voltage Si MOSFET, have become commercialized at around 650 V. However, reliability and robustness, especially against single event burn-out and/or single event gate rupture is critical. This paper experimentally investigates the performance of the listed FET devices under Unclamped Inductive Switching and Bias Temperature Instability/gate oxide stress tests.

Characterization of the onset of carrier multiplication in power devices by a collimated radioactive alpha source

The quantitative characterization of charge multiplication in reverse biased junctions is mandatory to design robust power devices, as well as to define their safe operating area. This applies especially for failure mechanisms like single event burnout, where the charge generated by ionizing radiation is transported and eventually multiplied by the internal electric field of the reverse-biased device. Because of their limited sensitivity, DC techniques detect charge multiplication as an increase of the reverse current of the junction once the breakdown already occurred. Optical and particle beams with dedicated test structures have been exploited to improve the sensitivity at lower electric field. However, the latter solutions cannot be simply applied to real devices. Furthermore, they just deliver averaged values of the multiplication factor.In this paper, single alpha particles from a collimated radioactive source are used to generate controlled charge bursts in the close vicinity of the reverse-biased junction of a power diode. The fast reverse current pulse arising to the drift of the initial charge burst is collected by a dedicated spectrometry chain. The acquired data are processed to obtain the probability distribution of the multiplication factor under consideration of the stochastic nature of the impact ionization process. The results of the measurements are compared with the multiplication values obtained by analytical models and by Monte Carlo simulation. The technique is demonstrated based on a commercial 1.2 kV-70A power diode in the reverse bias range from 700 V to 1250 V. Finally, detailed information is provided about the proposed hardware solutions, which can easily be implemented under usual laboratory conditions.

Calculation of single event burnout failure rate for high voltage devices under satellite orbit without fitting parameters

Increase of power bus voltages in spacecraft are expected with the power demand growth. Accordingly, high voltage semiconductor devices in the power supply system will be required to withstand high energy and high flux cosmic ray environment. In this paper, we propose a new formula to calculate failure rate for power semiconductor devices in space application.

A Simulation-Based Comparison Between Si and SiC MOSFETs on Single-Event Burnout Susceptibility

This paper presents the simulation-based comparison between silicon (Si) and silicon carbide (SiC) MOSFETs on the single-event burnout (SEB) performance for the first time. The safe operation areas (SOAs) regarding SEB are extracted and compared between the two structures when the heavy ions with a different linear energy transfer (LET) strike the sensitive areas of the devices. It is demonstrated that benefiting from the higher doped drift region, SiC MOSFET has a larger SEB threshold voltage than Si MOSFET at low LET range. However, it is the other way around at high LET range, which is attributed to the thicker epitaxy of Si MOSFET. The introduction of buffer layer to enhance the SEB hardness is also discussed. Results indicate that a thicker buffer layer is required for SiC MOSFET to enlarge the SOA, resulting in a more serious degradation of the specific ON-resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON},\textsf {sp}}$ ). Consequently, other hardening solutions need to be further explored to ensure the safe operation of SiC MOSFET in space applications.

Research of Single-Event Burnout and Hardening of AlGaN/GaN-Based MISFET

This brief first time presents single-event burnout (SEB) simulation results for conventional AlGaN/ GaN gate field plate MISFET (GFP-C MISFET), simultaneously, a hardened MISFET with electrode connected doped plugs in the buffer (EC-DP MISFET) is proposed for the first time. The SEB triggering mechanisms contain the back-channel effect and following impact ionization dominated by electron in the high field region. By comparing the simulation results from the GFP-C MISFET and proposed hardened EC-DP MISFET, the carriers induced by heavy ion can be quickly absorbed to drain and source electrode through EC-DP, so that the proposed EC-DP MISFET can achieve better SEB performance than conventional one. With a heavy ion having the linear energy transfer value of 0.6-pC/ $\mu \text{m}$ striking vertically, SEB threshold voltage obtained in GFP-C MISFET and hardened EC-DP MISFET is 280 and 338 V, respectively.

Estimating Terrestrial Neutron-Induced SEB Cross Sections and FIT Rates for High-Voltage SiC Power MOSFETs

Cross sections and failure in time rates for neutron-induced single-event burnout (SEB) are estimated for SiC power MOSFETs using a method based on combining results from heavy ion SEB experimental data, 3-D TCAD prediction of sensitive volumes, and Monte Carlo radiation transport simulations of secondary particle production. The results agree well with experimental data and are useful in understanding the mechanisms for neutron-induced SEB data.

Heavy Ion Transport Modeling for Single-Event Burnout in SiC-Based Power Devices

SiC power devices have been found experimentally to burn out from heavy ion strikes with linear energy transfers as low as 2.0 MeV $\cdot $ cm2/mg. In this paper, to better understand the failure mechanisms, we study the single-event burnout (SEB) phenomenon using a unified physics model between heavy ion radiation transport and device response. High-fidelity radiation data, generated from a general purpose Monte Carlo N-particle transport code (MCNP6.2), were modeled using a double Gaussian function to take into account both the heavy ion and the delta ray contributions. SiC junction barrier Schottky (JBS) diodes underwent 3-D TCAD electrothermal simulations using the double Gaussian model. This model was compared against other heavy ion models to determine the behavior of the thermal response from a heavy ion strike. The results reveal that there is a more rapid thermal response from models using high-fidelity heavy ion radiation data than approximated models provided by TCAD simulators. Peak temperature results from high-voltage SiC JBS diodes, which agree with the experimental observation of SEBs in SiC power devices.

Radiation Response of AlGaN-Channel HEMTs

We present heavy ion and proton data on AlGaN high-voltage HEMTs showing single event burnout (SEB), total ionizing dose, and displacement damage responses. These are the first such data for materials of this type. Two different designs of the epitaxial structure were tested for SEB. The default layout design showed burnout voltages that decreased rapidly with increasing LET, falling to about 25% of nominal breakdown voltage for ions with LET of about 34 MeV $\cdot $ cm2/mg for both structures. Samples of the device structure with lower AlN content were tested with varying gate–drain spacing and revealed an improved robustness to heavy ions, resulting in burnout voltages that did not decrease up to at least 33.9 MeV $\cdot $ cm2/mg. Failure analysis showed that there was consistently a point, location random, where gate and drain had been shorted. Oscilloscope traces of terminal voltages and currents during burnout events lend support to the hypothesis that burnout events begin with a heavy ion strike in the vulnerable region between gate and drain. This subsequently initiates a cascade of events resulting in damage that is largely manifested elsewhere in the device. This hypothesis also suggests a path for greatly improving the susceptibility to SEB as development of this technology goes forward. Testing with 2.5-MeV protons showed only minor changes in device characteristics.

Research of Single-Event Burnout in 4H-SiC JBS Diode by Low Carrier Lifetime Control

This paper presents the 2-D numerical simulation results of single-event burnout (SEB) in 4H-SiC junction barrier Schottky (JBS) diode by low carrier lifetime control (LCLC) for the first time. We investigate the SEB performance based on an 1800-V JBS structure and find that the most sensitive ion’s strike position is the middle of junction spacing because of the punchthrough of the electric field at anode contact. Then, the SEB hardening mechanism of LCLC is studied in this paper that the double-sided peak electric field can be effectively improved which results in a significantly decrease of maximal temperature. For the incident particle with different linear energy transfer values, we find that the SEB threshold voltage can be substantially enhanced when the carrier lifetime ( $\tau $ ) is under a certain value. In addition, the basic characteristics with LCLC are discussed that the forward and reversed characteristics are hardly affected.