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In this work, the influence of various oxide electric field (۳ܠܗ (stress conditions on the gate oxide lifetime, gate leakage current, and threshold voltage of 1.2 kV 4H-SiC power planar metal-oxide-semiconductor field-effect transistors (MOSFETs) is investigated. The results suggest that high ۳ܠܗ stress (&gt; 9.4 MV/cm) applied to the gate oxide of commercial SiC power MOSFETs for a certain period degrades the oxide lifetime due to high Fowler-Nordheim (F-N) electron tunneling current followed by hole trapping. Moreover, hole trapping enhances the gate leakage current and reduces the threshold voltage. Therefore, the generation of holes under high electric field conditions should be avoided to ensure the reliability of SiC power MOSFETs.

IEEE WiPDA 2022

Effects of Oxide Electric Field Stress on the Gate Oxide Reliability of Commercial SiC Power MOSFETs

gate oxide screening

lifetime

electron and hole trapping

gate oxide reliability

threshold voltage shift

The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.

**Topics of interest**

* Heteroepitaxial & Bulk Materials Growth
* Gate Dielectrics & Surface Passivation
* Device Structures & Fabrication Techniques
* Device Characterization & Modeling
* Very-High Efficiency or Compact Converters
* Safe Operating Areas of Wide Bandgap Devices, Including Short Circuit, Spike, & Transient Tolerance
* Harsh Environment (High Temperature) Operation & Reliability
* Packaging Power Modules & ICs
* Hard-Switched & Soft-Switched Application Analysis
* Gate Drive & Other Auxiliary Circuits
* High-Performance Passive Components
* Applications in Renewable Energy & Energy Storage, Transportation, Industrial Drives, & Grid Power Systems
* Wide Band Gap System Design Philosophies & Strategies
* Radio Frequency (RF) GaN (New)
* Technology Roadmap of Wide Bandgap Including Devices, Applications and Packaging (New)

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IEEE WiPDA 2021

The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.

In this work, the influence of various oxide electric field (۳ܠܗ (stress conditions on the gate oxide lifetime, gate leakage current, and threshold voltage of 1.2 kV 4H-SiC power planar metal-oxide-semiconductor field-effect transistors (MOSFETs) is investigated. The results suggest that high ۳ܠܗ stress (> 9.4 MV/cm) applied to the gate oxide of commercial SiC power MOSFETs for a certain period degrades the oxide lifetime due to high Fowler-Nordheim (F-N) electron tunneling current followed by hole trapping. Moreover, hole trapping enhances the gate leakage current and reduces the threshold voltage. Therefore, the generation of holes under high electric field conditions should be avoided to ensure the reliability of SiC power MOSFETs.

technical paper

Download the proceedings [here](https://underline.io/events/372/lounge)
 
 
 The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.
 
 **Topics of interest**
* Heteroepitaxial & Bulk Materials Growth
* Gate Dielectrics & Surface Passivation
* Device Structures & Fabrication Techniques
* Device Characterization & Modeling
* Very-High Efficiency Or Compact Converters
* Safe Operating Areas Of Wide Bandgap Devices, including Short Circuit, Spike, &Transient Tolerance
* Harsh Environment (High Temperature) Operation & Reliability
* Packaging Power Modules & ICs
* Gate Drive & Other Auxiliary Circuits
* High-Performance Passive Components
* Hard-Switched & Soft-Switched Application Analysis
* Applications in Renewable Energy & Energy Storage, Transportation, Industrial Drives, Grid Power Systems, Space and Aerospace
* Wide Bandgap System Design Philosophies & Strategies
* Radio Frequency (RF) GaN
* Technology Roadmap of Wide Bandgap Including Devices, Applications and Packaging

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瀆 It has been demonstrated that basal plane dislocations (BPDs)-induced stacking faults (SFs) cause body diode degradation in commercial 4H-SiC power MOSFETs, especially with higher voltage ratings. BPDs originate from 4HSiC boule, epi growth, and ion implantation. Considering the lower cost of ion implantation at room temperature (RT), this work investigates the potential of RT ion implantation replacing heated (HT) ion implantation by comparing the influence of both ion implantations on the body diode degradation of commercial 3.3 kV 4H-SiC power MOSFETs. We demonstrate with long-term (up to 1000 hours) forward current stress that RT implantation can keep the body diode degradation of 3.3 kV 4H-SiC power MOSFETs within the specification limits compared with HT implantation.

A Comparison of Ion Implantation at Room Temperature and Heated Ion Implantation on the Body Diode Degradation of Commercial 3.3 kV 4H-SiC Power MOSFETs

This paper presents a comparison of 1.2 kV 4H-SiC MOSFETs and Ti JBSFETs with deep P-well structures. For a fair comparison of the short-circuit characteristics between the MOSFETs and JBSFETs, an innovative design approach for the JBSFETs was implemented to obtain the same specific on-resistance to the MOSFETs. To improve the short-circuit characteristics of the MOSFETs and JBSFETs, channeling implantation was conducted to form a deep P-well structure, that helps reduce the maximum saturation current during the shortcircuit event. Using this approach superior short-circuit characteristics are achieved in the MOSFETs and JBSFETs. However, the JBSFETs provide a shorter shortcircuit withstand time than the MOSFETs due to the high leakage current from Schottky contact. Sentaurus 2D TCAD was used to understand and clarify the short-circuit mechanisms of the MOSFETs and JBSFETs. It was discovered that the MOSFETs failed due to the high current in the channel region, but the failure of JBSFETs happens in the Schottky contact. Moreover, solutions to improve the short-circuit characteristics of the JBSFETs are proposed; a narrow Schottky width and high work function metal.

A Comparison of Short-Circuit Failure Mechanisms of 1.2 kV 4H-SiC MOSFETs and JBSFETs

Neutron-induced failures in power electronics are a source of concern in many high-reliability applications. This paper describes how to estimate the device's decreased lifetime expectancy based on its usage. The physical mechanism, Failure in Time (FIT) statistics and FIT rate calculation methodology are presented. Several Microchip SiC MOSFETs and Schottky barrier diodes at different voltage ratings were tested, and the results for the excess FIT rate calculation based on various factors such as operation voltage, altitude, device area, latitude, and duty factor are presented.

Failure Rate Calculation Due to Neutron Flux with SiC MOSFETs and Schottky Diodes

The same core device model is shown to accurately reproduce the current-voltage and capacitance-voltage characteristics of enhancement-mode GaN 100 V power transistors of various sizes. Using linear scaling, excellent agreement with measurements is achieved over an order of magnitude variation in total gate width. Fractional variation in onresistance is shown to decrease with increasing transistor size, with implications for integrated circuit-sized transistors where gate width decreases by up to 5 orders of magnitude.

Scaling of EPC’s 100 V Enhancement-Mode Power Transistors

In this paper, we discuss how advancements in the integration of gallium nitride (GaN) power ICs leads to faster switching, higher efficiencies, simplifier designs and improved reliability. Navitas’ integrated GaNSense™ technology features provide real-time sensing and protection to achieve these new levels.

Advancement in Integration for GaN Power ICs

In this study, the impact and correlation of drainand gate-voltage stress on the threshold voltage of commercially available p-gate GaN HEMTs are investigated. This is based on single-pulse measurements acquired with a custom pulse setup, thus the transient behavior can be determined and subsequently translated into dc characteristics. As a novelty, measurements of the threshold voltage for short-circuit stress of up to 600 V are shown. As a result, a constant threshold voltage shift is observed for on-state drain-voltage stress, while off-state drain-voltage and gate-voltage stress lead to a threshold voltage instability. Finally, drain stress and gate stress appears to superimpose, consequently already application-relevant gate-driving conditions show a drastic impact of the short-circuit capability.

Threshold Voltage Behavior and Short-Circuit Capability of p-Gate GaN HEMTs Depending on Drain- and Gate-Voltage Stress

To reduce global warming / human health impacts, governments around the globe have been committed to reduce greenhouse gas and pollutant emissions.  To achieve these goals, vehicles with internal combustion engines (ICEs) are being replaced at very fast pace by vehicles with electrified power trains, (e.g., battery-electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), fuel-cell electric vehicles (FCEVs), etc.) To offer electrified functions, many power-electronic (PE) modules are incorporated on these vehicles (e.g., traction inverters, DC/DC converters, on-board / off-board chargers, etc.)  In these PE modules, WBG devices have shown promising potentials replacing Si ones to achieve better performance, smaller footprints, lighter weights, etc.  However, from many view angles, many WBG products are working under higher stresses than the Si ones to deliver better performance, leading to concerns of lower long-term reliability / higher parameter drifts.  To convince automotive manufacturers / suppliers, WBG vendors should disclose the raw-wafer / epi-layer defect info (e.g., densities, failure mechanisms, long-term aging effects, etc.), quality assurance processes and qualification results, EOL screening processes and pass/fail criteria, production yields, test-to-failure data (e.g., Weibull charts, bath-tub curves), and actual field return results.  For comparison, Si experience will be shared in this presentation.

Reliable wide-bandgap (WBG) products for safety-critical automotive applications – what are expected

GaN power devices have been in mass production for over 12 years [1] and have arguably crossed over the tipping point in adoption with such end-uses as cell phone fast chargers, DC-DC converters for servers, motor drives for electric bicycles and scooters, class-D audio amplifiers, and lidar sensors for autonomous vehicles and robots.  Some of these applications first started using discrete GaN transistors and later converted to GaN integrated circuits.  Others have stayed with discrete devices.  This paper will discuss the reasons for different adoption rates in different applications and will speculate on the changes that will occur due to new GaN transistor performance and new capabilities in integrating functions in GaN.

What is the Right Level of Integration for GaN Power Devices?

Our world’s sustainable future is linked to energy efficiency and GaN’s innovative technology. The world is witnessing a data explosion. The demand for a cleaner and healthier global environment clearly shows that sustainability must be more than a footnote in a company’s annual report. Yet, the energy-driven world is leading to historically high-power consumption due partly to our increased dependence on power-reliant industries, including data centers, electric vehicles, renewable energy systems, and consumer electronics. Technology helped create this problem. Now, it’s time for technology – specifically ‘GaN-Powered’ technology – to help solve this problem. From the humble chargers to the all-important EV powertrain, GaN power systems are solving today’s technical, economic, and environmental challenges. During this session, Jim Witham, CEO of GaN Systems, will discuss how GaN plays a crucial role in changing our relationship with power by enabling the creation of new sustainability solutions.

Designing with GaN to Solve Today’s Global Power Challenges

Wide bandgap semiconductors are expanding rapidly into legacy silicon applications, with a combined market opportunity over $22B by 2026. The voltage and power range where silicon MOSFETs are the preferred solution is now limited to less than 100V and less than 1kW, and even that range is shrinking. GaN is now preferred from 100V to 750V ratings and up to 20kW due to its extremely low losses, reduced chip sizes, and integrated solutions driving low system costs. SiC is a clear winner in high-efficiency and high-density applications for 800V and higher power rails, with power FETs and diodes ranging from 650V to 6,500V.  Switching frequencies are increasing in new topologies with GaN power ICs in applications such as data-center PFC and DC-DC stages, solar micro-inverters, and home appliance motor drives, with SiC FETS in advanced BLDC industrial motor drives and solar string-inverters. GaN device and application examples include new GaNSense half-bridge power ICs with loss-less current sensing and high-speed over-current protection enabling an advanced 140 W USB PD 3.1 fast-charger design, and a ‘Titanium Plus’ 2.7 kW CRPS AC-DC. Navitas‘ GeneSiC FETs enable high-frequency totem-pole PFC and motor drive while lowering energy loss compared to both silicon IGBTs and other SiC MOSFETs. Both technologies deliver cutting-edge performance in support of the mission to “Electrify Our World™” and reduce CO2 emissions.​

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A Comparison of Ion Implantation at Room Temperature and Heated Ion Implantation on the Body Diode Degradation of Commercial 3.3 kV 4H-SiC Power MOSFETs

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