Advanced Design and Integration of High Energy Thyristors – CARTHAGE

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.