Key power design considerations which will influence SiC device selection

Thanks to the numerous favourable attributes this technology possesses, engineers can overcome the performance limitations of silicon (Si) that are now becoming evident in a power system context. SiC-based devices are going to be instrumental in the widespread electrification of the transportation sector. They will also be a key factor in our society’s transition to renewable energy.   

Over the course of the last decade, many of the leading semiconductor vendors have made large financial outlays in order to add full-scale SiC fabrication to their overall production capabilities. As a result, the range of SiC-based devices now on the market is extensive. Over time, some of the older legacy fabs will be converted to SiC output while new fabs will be added, and the proportion of these vendors’ product shipments that rely on wide bandgap technology will continue to increase.

According to research conducted by analyst firm Yole, the global SiC device business will experience a compound annual growth rate (CAGR) of approximately 34% between now and 2027 – with it reaching a total worth of $6.3 billion by the end of that period. Among the key applications where these devices can really make a difference is in motor drives, solar power generation systems, data centre power supplies and energy storage resources, as well as in both electric vehicle (EV) charging infrastructure and EV powertrains.

Advantageous properties of SiC

Whichever of the available SiC devices design engineers decide to source, the performance enhancements that are derived from use of this semiconductor compound are clear. The most prominent of these is that SiC devices can deliver far higher switching speeds than their conventional Si counterparts. As a consequence of this, smaller magnetics can be used in the system layout and power densities thereby increased.

The energy saved efficiency improvements means EVs can run for longer between recharges, motors’ environmental impact can be mitigated, and photovoltaic cells are able to convert more sunlight into electricity. There are also advantages to be derived in relation to better thermal properties and higher breakdown voltages. This makes them suitable for incorporation into applications that are beyond the scope of Si. 

Economic aspects

Until now, SiC and other wide bandgap technologies, had to some extent been held back by the relatively high unit costs of such devices, due to additional costs associated with their fabrication. This was due to the initial applications that they were addressing not having high enough volumes to bring the necessary economies of scale that would lead to lower production expenses. A latency period before mass-market adoption was always to be expected however – as exactly the same dynamics came into play for early Si ICs when they first emerged six decades ago. With higher volume application opportunities now finally opening up, SiC is starting to gain real momentum.    

Ongoing SiC innovation

Infineon has made a major commitment to the long-term progression of SIC technology, providing the market with its CoolSiCproduct portfolio – which consists of a multitude of SiC-based diodes and MOSFET devices. Since 2001, the company has been producing commercial SiC devices in a high-volume semiconductor fabrication environment, with multi-million Euro investments recently being made in both Austria and Malaysia. The same tools and quality control measures are employed for its SiC production workflows as they are with Si-based power technologies. To enable greater differentiation from the competition, activities like epitaxial growth and advanced packaging implementation are both retained in-house.

Through the highly optimised process technology it has developed, alongside the innovative chip design methods used, Infineon has been able to minimise the defect rates of its SiC devices. Consequently, they emulate the reliability levels that would normally be associated with Si technology – with only a single failure being seen every 10⁹ hours (1FiT).

The combination of SiC-based process technology with Infineon’s proprietary diffusion soldering technique and advanced interconnect mechanisms substantially augments the thermal dissipation capabilities of its CoolSiC™ devices in discrete packages (typically by around 25%).

CoolSiC devices have been shown to shorten EV charging times by as much as 50%, by enabling the building of charging stations with higher power charging points. Likewise, they enable 2.5x greater power densities to be realised in solar inverters. Depending on the specific operating conditions involved, energy losses can be reduced dramatically. In the case of industrial motors drives, the CoolSiC MOSFETs can have up to have 80% lower losses than Si IGBTs.

Matching semiconductor engineering skills with supply chain knowhow

Back in last summer, EBV and Infineon announced a strategic partnership in relation to the semiconductor vendor’s CoolSiCportfolio (which features over 250 products in total). Drawing on EBV’s channel expertise and Infineon’s decades’ worth of work in SiC development, the objective of this collaboration is to encourage greater uptake of wide bandgap technology across a more expansive cross section of different industry sectors.

Via their partnership, the two companies are participating in a variety of different activities. They are, for example, jointly conducting in-depth training programmes. Through these, design engineers can get all the technical guidance they need when either looking to implement new SiC-based power systems or retrofit this technology into existing ones - the outcome being that the projects they undertake have a better chance of proving successful. In addition, design engineers can gain advice on what are likely to be the best optimised SIC devices to select given their exact design/application criteria.   

Figure 1: The EVAL-1ED3122MC12H-SiC evaluation board available from EBV

In terms of hardware to support the Infineon SiC portfolio, EBV is able to offer the entry-level EVAL-1ED3122MC12H-SiC evaluation board. This board enables engineering teams to experiment with different concepts and assess their feasibility, before starting on prototype designs. It is comprised of a pair of CoolSiC MOSFETs placed into a half-bridge configuration. These are accompanied by 1ED-X3 single-channel isolated 10A gate drivers, plus additional power supply circuitry. The board can be used to determine the performance characteristics of 650V and 1200V rated CoolSiC MOSFETs, with both of these options being supplied a part of the package. It exhibits a >200kV/µscommon-mode transient immunity (CMTI). 

An undoubtedly promising future lies ahead for SiC

It is evident that the benefits of SiC technology are now being fully appreciated - with continued technological advancement, new potential applications, plus greater market acceptance all helping to make it more commercially viable across a broader array of industry sectors. Consequently, it has now gone way beyond just being applicable to a few niche applications - and is starting to contribute to mainstream electronics. Through game-changing products, like those in Infineon’s CoolSiC portfolio of power discretes, notable boosts in power system performance are set to be realised, and society is certain to reap the rewards.