Расчет характеристик карбидокремниевых диодов Шоттки для малогабаритных металлополимерных корпусов

Выполнен расчет характеристик охранной системы карбидокремниевых 4H-S1C диодов Шоттки с использованием метода физического моделирования и установлены оптимальные конфигурации (уровни легирования и толщины эпитаксиального слоя 4H-S1C) структуры диода для получения высоких значений пробивного напряжени

Design, simulation and fabrication of 4H-SiC Power MOSFETs

For a 4H-SiC MOSFET to compete with Si counterparts, especially at lower voltages (1.2kV), the channel resistance contributes to a significant part in the total on-state resistance which must be addressed. Since most of the commercially available SiC wafer materials are grown on the {0001} crystal plane, a trench-gate MOSFET is necessary to take the advantage of the higher reported channel mobility on the {112 ̅ 0} crystal plane. 1.2kV trench MOSFET design and fabrication is the main focus in this work. The micro-trench free dry etching process has first been developed with a systematic study on the dry etching parameters. Trench corner rounding has also been investigated since a rounded corner is normally preferred to avoid an electric field hot spot. Two generations of trench MOSFETs have been designed and fabricated. The 1st generation devices have been used to validate the fabrication process. A maximum breakdown voltage of 1600V has been achieved for the 1st generation devices. The p+ trench bottom shielding region provides the protection for the trench gate oxide since it shifts the peak electric field from the oxide/semiconductor interface to a semiconductor p-n junction; however, it also introduces a parasitic JFET region into the trench MOSFET structure which severely degraded the on-state performance of the 1st generation devices. The 2nd generation devices were designed to eliminate the effect of the parasitic JFET region and improve the on-state performance. The optimised device structure with a current spreading layer (CSL) and p+ implantation clearance in the 2nd generation design has successfully eliminated the effect of the parasitic JFET region. Further design and process optimisation is necessary to increase the current density of the device which was as low as 3A/cm2. A fabrication trial has been carried out on the MOSFETs with integrated Schottky contacts at the termination region and therefore, external Schottky diodes are not necessary for many applications. A 10kV DMOSFET has also been designed and fabricated with maximum breakdown voltage at 13.6kV. The high voltage termination design options have been discussed among the floating field ring (FFR) termination and the junction termination extensions (JTEs). The on-state performance is poor due to a photo mask error on the JFET length which needs to be optimised for the next generation devices. Novel device structures have been studied with simulation. These include trench MOSFET with integrated Schottky diode and 3.3kV superjunction trench MOSFET. The MOSFET with integrated Schottky diode not only reduces the chip area consumption, but also reduces the chip count in the system level. In the proposed design, the Schottky contact is placed at the bottom of the trench structure for the first time. The superjunction structure has a great potential for SiC devices rated at above 3.3kV. The proposed design uses implanted p-pillar with a trench gate structure which combines the benefits of low channel resistance and low drift region resistance

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

Contribution à l'étude de la fiabilité des technologies avancées en environnement radiatif atmosphérique et spatial par des méthodes optiques

Ce travail présente la mise en œuvre du test par faisceau laser TPA pour l étude de la sensibilité au phénomène SEB dans les diodes schottky en carbure de silicium. Le contexte de l étude est décrit par un état de l art du SEB sur les MOSFETs et Diodes en Silicium et en carbure de silicium. Une étude technologique et structurelle des composants en SiC a permis de dégager les avantages du SiC par rapport au Si conventionnel et a permis d analyser les dégâts causés par le faisceau TPA. L utilisation du montage expérimental sur la plateforme ATLAS dédié spécifiquement au test de matériaux à grand gap a permis de mettre en place une méthodologie de test sur des diodes schottky en SiC. L efficacité de cette méthodologie est prouvée par l obtention de résultats expérimentaux très originaux. La susceptibilité au SEB induit par la technique laser TPA a été démontrée. Les mesures SOA ont permis d évaluer la robustesse des diodes schottky SiC face aux événements singuliers. Une modélisation analytique a été menée afin de comprendre la cause du mécanisme du SEB et la localisation des défauts induits par le faisceau TPA.This work presents the implementation of the TPA laser beam testing to study the SEB phenomenon in silicon carbide Schottky diodes. The context of the study is described by a state of the art of SEB on Si and SiC MOSFETs and Diodes. Technological and structural study of SiC components has identified the benefits of SiC compared to conventional Si and permits to analyze the damage caused by the TPA beam. Using the experimental setup of the ATLAS platform dedicated specifically to test large gap materials has set up a test methodology on SiC Schottky diodes. The effectiveness of this methodology is demonstrated by obtaining original experimental results. Susceptibility to SEB induced by TPA laser technique has been demonstrated. SOA measurements were used to assess the robustness of SiC Schottky diodes to single event effects.An analytical modeling was conducted to understand the cause of the SEB mechanism and the location of defects induced by the TPA beam.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Design, simulation, fabrication and characterisation of 4H-SiC trench MOSFETs

For solid-state power devices, there exists need for a material with a higher band gap which will result in a higher critical electric field, improved power efficiency and thermal performance. This has resulted in the use of Silicon Carbide (SiC) as a serious alternative to Silicon for power devices. SiC trench MOSFETs have attracted major attention in recent years because of 1) lower on resistance by eliminating the JFET effect which exists in lateral MOSFETs, 2) higher channel density which lowers the threshold voltage and 3) reduction of the required surface area because of the vertical channel. These advantages allow faster switching speeds and the potential for a higher density of devices leading to more compact modules. This work was focused on fabrication of the first generation of 4H-SiC trench MOSFETs in Warwick University. Two main goals were achieved in this work: a comprehensive understanding of fabrication of trenches in 4H-SiC and fabrication of first generation of 4H-SiC trench MOSFET with mobility as high as 3

Activation des dopants implantés dans le carbure de silicium (3C-SiC et 4H-SiC)

Ces travaux de thèse sont consacrés à l étude de l activation des dopants implantés dans le carbure de silicium. L objectif est de proposer des conditions d implantation optimisées pour réaliser le dopage de type n dans le 3C-SiC et de type p dans le 4H-SiC.Nous avons tout d abord étudié les implantations de type n dans le 3C-SiC. Pour cela, des implantations de N, de P et une co-implantation N&P avec les recuits d activation associés ont été étudiés. L implantation d azote suivie d un recuit à 1400C-30min a permis une activation proche de 100% tout en conservant une bonne qualité cristalline. Une étude sur les propriétés électriques des défauts étendus dans le 3C-SiC a également été réalisée. A l aide de mesures SSRM, nous avons mis en évidence l activité électrique de ces défauts, ce qui rend difficile la réalisation de composants électroniques sur le 3C-SiC.Nous avons ensuite réalisé une étude du dopage de type p par implantation d Al dans le 4H-SiC, en fonction de la température d implantation et du recuit d activation. Nous avons pu montrer qu une implantation à 200C suivie d un recuit à 1850C-30min donne les meilleures résultats en termes de propriétés physiques et électriques.This work was dedicated to the activation of implanted dopants in 3C-SiC and 4H-SiC. The goal is to propose optimized process conditions for n-type implantation in 3C-SiC and for p-type in 4H-SiC.We have first studied the n-type implantation in 3C-SiC. To do so, N, P implantations, N&P co-implantation and the associated annealings were performed. The nitrogen implanted sample, annealed at 1400C-30 min evidences a dopant activation rate close to 100% while maintaining a good crystal quality. Furthermore, the electrical properties of extended defects in 3C-SiC have been studied. Using the SSRM measurements, we have evidenced for the first time that these defects have a very high electrical activity and as a consequence on future devices.Then, we have realized a study on p-type doping by Al implantation in 4H-SiC with different implantation and annealing temperatures. Al implantation at 200C followed by an annealing at 1850C-30min lead to the best results in terms of physical and electrical properties.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Sicilia—silicon carbide detectors for intense luminosity investigations and applications

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance

Simulation study of silicon carbide Clustered Insulated Gate Bipolar Transistor (CIGBT)

Power semiconductor devices are inevitable parts of a power electronic converter system, with nearly 50% of electricity used in the world controlled by them. Silicon power devices have been used in power systems ever since the vacuum tubes were replaced by them in the 1950s. The performance of devices in a circuit is decided by the switching strategies and the inherent device performance like its on-state voltage, turn-on and turn-off times and hence their losses. Due to their inherent material properties, the growing interest in wide band gap devices is in applications beyond the limits of Si or GaAs. SiC is a wide bandgap material with properties that make it an attractive alternative to Silicon for high power applications. Silicon Insulated Gate Bipolar Transistor (IGBT) is the most favourable device in the industry today for medium/high power applications. Silicon Clustered Insulated Gate Bipolar Transistor (CIGBT) is experimentally proven to demonstrate better performance as compared to their IGBT counterparts. In this work, the theoretical limit of silicon CIGBT is studied in great detail and compared to previously predicted IGBT limit. Later part of this thesis would explain the design and optimization of CIGBT in 4H- SiC. An in-depth simulation study of the same device is performed for both static and dynamic characteristics. Both planar and trench gate CIGBT devices are discussed here along with possible fabrication process. Along with this, a comparison study between CIGBT with its equivalent IGBT in SiC is also performed through extensive 2D simulations in MEDICITM in terms of their static and dynamic characteristics. Finally, a comparative study of P channel and N channel SiC CIGBT devices is evaluated through simulations