The research and development in the fields of green renewable energies are one of the main targets for the future of humanity. The yield improvement of the energy chain absolutely needs a yield improvement of each part of it. The transport sector, for example, consumes 25% of world energy and uses more than half of the oil produced in the world. Consequently, the research orientations related to the use of alternative energies for road transport (hybrid and electric vehicles for instance) are of the most importance, but it will also be vital in the future to modify the ways of life associated to the use of private vehicles and the energy consumption. Research activities in power electronics fully address these future changes. There are numerous power electronics applications (electrical traction, industrial drives, distribution network management, electrical household appliances, transport and portable units,…) using a large variety of power devices. The drastic performance improvement of these power devices, in terms of energy saving, cost, size, weight and reliability, is a key factor for the safeguard of the energy. This is the context of the « SUPER SWITCH » research project here proposed . The main objective of this project is to propose alternative solutions to the IGBT in power converters in the 600-1200 V breakdown voltage range. Today, up to 600 V, the main IGBT competitor is the MOSFET. Indeed, the MOSFET exhibits many interesting properties for power applications (high switching speed, high input impedance, thermal stability, internal free-wheeling diode) but, in high voltage range (600-1200 V), it is limited by its high specific on-resistance and, therefore, its important on-state voltage drop, which induces more on-losses, compared to bipolar devices: to find the best trade-off between these two parameters (specific on-resistance / breakdown voltage) is one of the major challenges for unipolar switches in this voltage range. For this reason, several innovative unipolar structures have been recently proposed to overcome the theoretical limit of the “specific on-resistance / breakdown voltage” trade-off of conventional unipolar power devices. The best structure is the well-known SuperJunction MOSFET firstly manufactured by Infineon (COOLMOS™) and STMicroelectronics (MDMESH™). These devices are fabricated by multi-epitaxy, which is an expensive process. In this project, we propose new technological ways for the realization of SuperJunction devices (diodes and MOSFETs) in the 600-1200 V voltage range, using a single epitaxy proccess: the realization of very performant power switches, at a lower cost compared to conventional processes of Infineon and STMicroelectronics, will be possible if the project succeeds. Actually, based on complementary competences of LAAS-CNRS, LMP, IMS and IBS, the « SUPER SWITCH » project proposes a new technological process, using only one epitaxy for the realization of Deep Trench SuperJunction Diodes (DT-SJDiodes) and MOSFETs (DT-SJMOSFETs) including an original termination, called Deep Trench Termination (DT2). Since SuperJunction device performances are very sensitive to charge balance, several critical process steps have to be studied and developed: deep etching with a perfect verticality of the trench sidewalls, doping technique along trench sidewalls and trench filling with a suitable dielectric able to fill deep and wide as well as shallow trenches. The influence of these steps on electrical and thermal performances will be also investigated by means of simulation tools. Process simulations will allow to define the optimal fabrication process of Deep Trench SuperJunction devices. Finally, DT-SJDiodes, DT-SJMOSFETs and DT2 will be fabricated and characterized in terms of electrical performance, thermal performance and robustness.

The civilian market for SiC power devices has been driven by an exponential growth since the 2010s, thanks to the needs of automotive and solar industry. The industrial offer is now mature for 1200 V and 1700 V SiC components, either diodes, MOSFETs. However, the higher the breakdown voltage goes, the sparser the market offer gets. This results from lesser market size, and technological difficulties that remain to be solved. However, SiC semiconductor is probably even more attractive for higher voltages range (3.3kV-10kV) when compared to Si solutions. It is worth noticing that at higher breakdown voltage class bipolar transistors such as GTOs are expected to be available earlier than MOSFETs because of their higher current and voltage capabilities, and the more complex reliability issues for the latter transistor. So bipolar devices will be relevant for the civilian market, even if they are deemed less convenient application-wise. One of the most straightforward application of high voltage SiC thyristor is pulsed power electronics. In this sense, Institut Saint Louis (ISL) and Ampère laboratory have been studying extensively the potential of the SiC technology to design and build efficient thyristors able to cope with high voltage and high peak current capabilities. These studies allowed creating a large quantity of knowledge and knowhow almost unique in the field, at least in Europe. The CARTHAGE project presents an opportunity to transform the previously developed concepts by ISL+Ampère in a semi-industrial product using stable, repetitive and in-line controlled processing. Based on these observations, the Carthage partners jointly believe that it is now feasible to develop, prototypes and test advanced SiC thyristors, and once packaged demonstrate their performances and potential for civilian and military applications (reaching then TRL 5). The CARTHAGE project aim to provide such a demonstration. Also, the number of wafers to be processed has been chosen to provide first estimates of yield as well as, hopefully, a final number of functional devices commensurate with future demonstrations of system applications, especially for military use cases. In this sense, the project integrates different objectives and related activities which will cover the product’s value chain. The first objective is to transfer the SiC thyristor fabrication technology in a semi-industrial processing platform, with the objective to mature and stabilize the fabrication process and allow the production of reasonable number of reliable chips (>200) per batches. For this purpose, it is important to study and improve the integration of large area devices while limiting the stacking faults degradation. Another target is to adapt and optimize the design of the thyristor architecture, including the high voltage edge termination, to the novel technology platform. A task to optimize an assembly and packaging technology adapted to high-pulsed current density and high power density operation is also required and a main target of the project. The last objective will be to demonstrate the full value chain from material to characterization in an application subsystem. To reach these goals, a consortium including a combination of complementary academic and industrial partners (CEA-Leti, ISL, Ampère, IBS, DEEP Concept) has been built in order to cover the value chain from starting semiconductor material to the component characterization in a subsystem. The complementarity of the partner will not only allow to reach the technical objectives but also to bring new insights in the physics and general understanding of SiC processing technology. In addition, the partners have a long collaboration background on SiC and power devices in general, which will allow a good understanding and efficiency in the scientific and technical interactions.

The OXIGEN project aims to develop a new crystalline silicon (c-Si) photovoltaic (PV) cell generation, and to obtain = 23% efficiency on large area devices. The studies will focus on the fabrication of ultra-thin junctions and functionalized oxides to reach transparent and passivated contacts using industrial processes. Two technologies will be highlighted in this project, the first one being Plasma Immersion Ion Implantation (PIII) which is ideal to obtain ultra-thin junctions. The second one, based on fast Atomic Layer Deposition (ALD), is developed by the French company Encapsulix and will be used for the fabrication of innovative electrodes allowing both surface passivation and charge carrier collection. This collaboration in the field of functionalized oxides for c-Si PV cells will be great to share high level scientific knowledge and research tools. The project will be coordinated by CEA-LITEN (LHMJ) because most of the process integration will be done at INES facilities. The scientific expertise of four academic labs (INL, LMGP, IMEP LAHC, GEEPS-IPVF) on the thin films/interface/device fabrication, simulation and characterizations will be necessary for all technological improvements of OXYGEN cells structures. All technological and scientific improvements will be done in collaboration with a start-up (ENCAPSULIX), which will offer specific skills in industrial process development.

The evolution of energy requirements due to increased electrical applications and consumption but also to the diversification of technologies linked to the renewable energy development lead to modify transport, distribution and energy management methods (i.e smart-grids, HVDC,…). In this context, the emergence of power devices suitable for harsh environments (e.g. high-voltage, high-frequency, high temperature, radiated environments, …) is expected to address transforming the current electric grid to the future grid. For example, power converter technologies have to be adapted and semiconductor switches have to comply with breakdown voltages well above 10 kV. The wide band gap (WBG) semiconductors, with theirs electronic and electrothermal properties, allow fabricating power devices operating at high voltage, high frequency and high temperature. Over recent years, several innovative wide bandgap power devices have been proposed and commercialized, the most known are SiC power MOSFET (Wolfspeed) and GaN HEMT (EPC, GaN System). The interest of these semiconductor materials is to overcome the “specific on-resistance/breakdown voltage” trade-off limit of silicon conventional power devices In such a context, Diamond is a good candidate to address several of the aforementioned issues. Its electrical properties (bandgap, thermal conductivity, charge-carrier mobility, critical electric field) are undoubtedly the highest among other semiconductors. However, Diamond is the technologically least mature semiconductor. The ambitious aim of the MOVeToDiam project is to create breakthrough by developing crucial Diamond technological steps to design and fabricate the next generation of power devices operating at 300°C as a vertical p-channel MOSFET U gate (Diam-UpMOSFET), and a very high voltage diamond TMBS diode (Trench MOS Barrier Schottky). Demonstration of the feasibility of these Diamond devices, requires basic research with high potential for disruptive technologies such as n and p-type diamond layers stacking, low resistive ohmic contacts on both diamond types, diamond/dielectric interface states control and vertical trench gate etching. Such challenges can be raised thanks to the international and complementary expertise in the development of technological bricks, specific to the diamond field of 4 academic laboratories, namely LSPM, GEMaC, AMPERE as well as LAAS, and the IBS Company. This p-channel vertical power MOSFET based on single crystal diamond and TMBS diode will allow France to be the forerunner and achieve low size, low weight, integrated and efficient power modules operating at high frequencies. These systems will be used on green transports and smart energy grid, major fields of interest in sustainable development. These researches would enable France to be the leader in the Diamond technology applied to very high voltage fields.