Viable 3C-SiC-on-Si MOSFET design disrupting current Material Technology Limitations

The cubic polytype (3C-) of Silicon Carbide (SiC) is an emerging semiconductor technology for power devices. The featured isotropic material properties along with the Wide Band Gap (WBG) characteristics make it an excellent choice for power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). Nonetheless, material related limitations originate from the advantageous fact that 3C-SiC can be grown on Silicon (Si) wafers. One of these major limitations is an almost negligible activation of the p-type dopants after ion implantation because the annealing has to take place at relatively low temperatures. In this paper, a novel process flow for a vertical 3C-SiC-on-Si MOSFET is presented to overcome the difficulties that currently exist in obtaining a p-body region through implantation. The proposed design has been accurately simulated with Technology Computer Aided Design (TCAD) process and device software and a comparison is performed with the conventional SiC MOSFET design. The simulated output characteristics demonstrated a reduced on-resistance and at the same time it is shown that the blocking capability can be maintained to the same level. The promising performance of the novel design discussed in this paper is potentially the solution needed and a huge step towards the realisation of 3C-SiC-on-Si MOSFETs with commercially grated characteristics

シリコンカーバイドパワーMOSFETsの破壊耐量ならびにそのメカニズムに関する研究

筑波大学 (University of Tsukuba)201

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

Diamond power devices: State of the art, modelling and figures of merit

With its remarkable electro-thermal properties such as the highest known thermal conductivity (~22W/cmbold dotK at room temperature) of any material, high hole mobility (> 2000cm2/Vbold dots), high critical electric field (>10MV/cm), and large bandgap (5.47eV), diamond has overwhelming advantages over silicon and other wide bandgap semiconductors (WBG) for ultra-high- voltage and high temperature applications (>3kV and >450 K, respectively). However, despite their tremendous potential, fabricated devices based on this material have not delivered yet the expected high-performance. The main reason behind this is the absence of shallow donor and acceptor species. The second reason is the lack of consistent physical models and design approaches specific to diamond-based devices that could significantly accelerate their development. The third reason is that the best performances of diamond devices are expected only when the highest electric field in reverse bias can be achieved, something that has not been widely obtained yet. In this context, high temperature operation and unique device structures based on the 2DHG formation represent two alternatives which could alleviate the issue of the incomplete ionization of dopant species. Nevertheless, ultra-high temperature operations and device parallelization could result in severe thermal management issues and affect the overall stability and long-term reliability. Additionally, problems connected to the reproducibility and the long-term stability of 2DHG based-devices still need to be resolved. This review paper aims at addressing these issues by providing the power device research community with a detailed set of physical models, device designs and challenges associated to all the aspects of the diamond power device value chain, from the definition of figures of merits, the material growth and processing conditions, to packaging solutions and targeted applications. Finally, the paper will conclude with suggestions on how to design power converters with diamond devices and will provide the roadmap of diamond devices development for power electronics.This work was supported by the U.K. Engineering and Physical Sciences Research Council for the University of Cambridge Centre for Doctoral Training under Grant EP/M506485/1 and by the French ANR Research Agency under grant ANR-16-CE05-0023 #Diamond-HVDC. The research leading to these results has been performed within the GREENDIAMOND project and received funding from the European Community's Horizon 2020 Programme (H2020/2014–2020) under grant agreement no. 640947

High-voltage SiC power devices for improved energy efficiency

Silicon carbide (SiC) power devices significantly outperform the well-established silicon (Si) devices in terms of high breakdown voltage, low power loss, and fast switching. This review briefly introduces the major features of SiC power devices and then presents research works on breakdown phenomena in SiC pn junctions and related discussion which takes into account the energy band structure. Next, recent progress in SiC metal-oxide-semiconductor field effect transistors, which are the most important unipolar devices, is described with an emphasis on the improvement of channel mobility at the SiO2/SiC interface. The development of SiC bipolar devices such as pin diodes and insulated gate bipolar transistors, which are promising for ultrahigh-voltage (>10 kV) applications, are introduced and the effect of carrier lifetime enhancement is demonstrated. The current status of mass production and how SiC power devices can contribute to energy saving are also described

Smart Power Devices and ICs Using GaAs and Wide and Extreme Bandgap Semiconductors

We evaluate and compare the performance and potential of GaAs and of wide and extreme bandgap semiconductors (SiC, GaN, Ga2O3, diamond), relative to silicon, for power electronics applications. We examine their device structures and associated materials/process technologies and selectively review the recent experimental demonstrations of high voltage power devices and IC structures of these semiconductors. We discuss the technical obstacles that still need to be addressed and overcome before large-scale commercialization commences

A digital-controlled SiC-based solid state circuit breaker with soft switch-off method for DC power system

Due to the lower on-state resistance, direct current (DC) solid state circuit breakers (SSCBs) based on silicon-carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) can reduce on-state losses and the investment of the cooling system when compared to breakers based on silicon (Si) MOSFETs. However, SiC MOSFETs, with smaller die area and higher current density, lead to weaker short-circuit ability, shorter short-circuit withstand time and higher protection requirements. To improve the reliability and short-circuit capability of SiC-based DC solid state circuit breakers, the short-circuit fault mechanisms of Si MOSFETs and SiC MOSFETs are revealed. Combined with the desaturation detection (DESAT), a “soft turn-off” short-circuit protection method based on source parasitic inductor is proposed. When the DESAT protection is activated, the “soft turn-off” method can protect the MOSFET against short-circuit and overcurrent. The proposed SSCB, combined with the flexibility of the DSP, has the μs-scale ultrafast response time to overcurrent detection. Finally, the effectiveness of the proposed method is validated by the experimental platform. The method can reduce the voltage stress of the power device, and it can also suppress the short-circuit current