Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments

Silicon-Carbide device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon counterpart, Silicon-Carbide offers a greater possibility for high powered switching applications in extreme environment. In particular, Silicon-Carbide Metal-Oxide- Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing Silicon-Carbide power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments

Long-Term Reliability of a Hard-Switched Boost Power Processing Unit Utilizing SiC Power MOSFETs

Silicon carbide (SiC) power devices have demonstrated many performance advantages over their silicon (Si) counterparts. As the inherent material limitations of Si devices are being swiftly realized, wide-band-gap (WBG) materials such as SiC have become increasingly attractive for high power applications. In particular, SiC power metal oxide semiconductor field effect transistors' (MOSFETs) high breakdown field tolerance, superior thermal conductivity and low-resistivity drift regions make these devices an excellent candidate for power dense, low loss, high frequency switching applications in extreme environment conditions. In this paper, a novel power processing unit (PPU) architecture is proposed utilizing commercially available 4H-SiC power MOSFETs from CREE Inc. A multiphase straight boost converter topology is implemented to supply up to 10 kilowatts full-scale. High Temperature Gate Bias (HTGB) and High Temperature Reverse Bias (HTRB) characterization is performed to evaluate the long-term reliability of both the gate oxide and the body diode of the SiC components. Finally, susceptibility of the CREE SiC MOSFETs to damaging effects from heavy-ion radiation representative of the on-orbit galactic cosmic ray environment are explored. The results provide the baseline performance metrics of operation as well as demonstrate the feasibility of a hard-switched PPU in harsh environments

Investigation of the impact of neutron irradiation on SiC power MOSFETs lifetime by reliability tests

High temperature reverse-bias (HTRB), High temperature gate-bias (HTGB) tests and electrical DC characterization were performed on planar-SiC power MOSFETs which survived to accelerated neutron irradiation tests carried out at ChipIr-ISIS (Didcot, UK) facility, with terrestrial neutrons. The neutron test campaigns on the SiC power MOSFETs (manufactered by ST) were con-ducted on the same wafer lot devices by STMicroelectronics and Airbus, with different neutron tester systems. HTGB and HTRB tests, which characterise gate-oxide integrity and junction robustness, show no difference between the non irradiated devices and those which survived to the neutron irradiation tests, with neutron fluence up to 2 × 1011 (n/cm2). Electrical characterization performed pre and post-irradiation on different part number of power devices (Si, SiC MOSFETs and IGBTs) which survived to neutron irradiation tests does not show alteration of the data-sheet electrical parameters due to neutron interaction with the device

Correlation between OCVD carrier lifetime vs temperature measurements and reverse recovery behavior of the body diode of SiC power MOSFETs

The reverse recovery (RR) behavior of SiC MOSFET body diode is of great importance in power application, where these devices are used in a wide range of operating temperatures. The carrier lifetime in the drift region varies with temperature, and it heavily affects the tailoring of the RR current, opening reliability issues related to the RR voltage amplitude and to possible anomalous voltage oscillations during the recovery. From the users' point of view, it would be useful to have a simple technique able to give predictive information about the body diode RR behavior of commercial devices over the whole range of working temperatures. An experimental-simulation approach is presented in this paper to correlate the carrier lifetime measured by simple OCVD measurements versus temperature with the RR behavior of the body diode, that can be useful at the design stage of power converters. Simulations of the body diode reverse-recovery are performed for a wide range of carrier lifetimes. This allows to estimate the effect of changes of carrier lifetime with temperature on the body diode switching transients. Preliminary results obtained with a 1700 V/5A commercial MOSFET are shown

Analysis of the 1st and 3rd Quadrant Transients of Symmetrical and Asymmetrical Double-Trench SiC Power MOSFETs

In this paper, performance at 1 st and 3 rd quadrant operation of Silicon and Silicon Carbide (SiC) symmetrical and asymmetrical double-trench, superjunction and planar power MOSFETs is analysed through a wide range of experimental measurements using compact modeling. The devices are evaluated on a high voltage clamped inductive switching test rig and switched at a range of switching rates at elevated junction temperatures. It is shown, experimentally, that in the 1 st quadrant, CoolSiC (SiC asymmetrical double-trench) MOSFET and SiC symmetrical double-trench MOSFET demonstrate more stable temperature coefficients. Silicon Superjunction MOSFETs exhibits the lowest turn-off switching rates due to the large input capacitance. The evaluated SiC Planar MOSFET also performs sub-optimally at turn-on switching due to its higher input capacitance and shows more temperature sensitivity due to its lower threshold voltage. In the 3 rd quadrant, the relatively larger reverse recovery charge of Silicon Superjunction MOSFET negatively impacts the turn-OFF transients compared with the SiC MOSFETs. It is also seen that among the SiC MOSFETs, the two double-trench MOSFET structures outperform the selected SiC planar MOSFET in terms of reverse recovery

Experimentally validated methodology for real-time temperature cycle tracking in SiC power modules

© 2018 Elsevier Ltd The ability to monitor temperature variations during the actual operation of power modules is key to reliability investigations and the development of lifetime prediction strategies. This paper proposes an original solution, specifically devised with novel fast-switching silicon carbide (SiC) power MOSFETs in mind. The results show ability to track temperature variations resulting from active power cycling of the devices, including high speed transients, thus enabling to discriminate among different potential failure mechanisms. Validation of the proposed methodology and its accuracy is carried out with the support of infrared thermography

Non-intrusive methodologies for characterization of bias temperature instability in SiC power MOSFETs

The gate oxide reliability of SiC power MOSFETs remains a challenge, despite the improvements of the new generation power devices. The threshold voltage drift caused by Bias Temperature Instability (BTI) has been subject of different studies and methods have been proposed to evaluate the real magnitude of the threshold voltage shift. These methodologies usually focus on the characterization of the threshold voltage shift, rather than its implications to the operation or how the threshold voltage shift can be detected during the application. This paper presents two non-intrusive methodologies which can assess and determine the impact of BTI-induced. The proposed methodologies are able to capture the peak shift and subsequent recovery after stress removal

Electrothermal power cycling of 15 kV SiC PiN diodes

Through extensive experimental measurements for the static and dynamic characteristics, the commercially available 15 kV Silicon Carbide (SiC) PiN diode are evaluated by power cycling. The forward voltage of diodes is used to indirectly measure the junction temperature. The SiC PiN diodes feature smaller die size, less reverse recovery charge and less on-resistance when compared to the commercially available closely rated Silicon PiN diodes. Nevertheless, during the power cycling experiments, the bipolar degradation and the degradation of contact metallization in SiC PiN diode gives rise to the increase of on-resistance even though its on-state losses is not as high as in the Silicon device. Such degradations are not observed from the Silicon PiN diode for the same junction temperature and the same high-temperature duration