Power electronics: SiC is on a roll – The chronicles by Yole SystemPlus

After the release of the first wafers in 1991, SiC evolved fairly slowly, with the launch of the first full SiC commercial MOSFET only twenty years later. In the end, it was Tesla and its 400V inverter that propelled the composite to the forefront in 2018. Since then, there has been increasing interest in SiC-based products that feature high power density, efficiency, and high-temperature performance to the delight of the automotive market segment looking for a solution to fulfill the requirements of under-the-hood applications. The figures provided by Yole Intelligence in the Power SiC 2022 report speak for themselves: the SiC devices market is expected to increase with a CAGR(2021-2027) over than 30% to reach beyond US$6 billion in 2027, with automotive expected to represent around 80% of this market. For the same reasons as for automotive, SiC has started to find its place in the energy sector and could also find its way into high-power industrial applications within the next decade. However, it’s not the ending of the SiC story. With Tesla’s announcement on SiC reduction in their future powertrain, both market value and technology could be changed according to the OEM’s choice.

With APEC (Applied Power Electronics Conference) about to commence in Orlando (from 19 to 23 March), Yole Group and its entities, Yole Intelligence and Yole SystemPlus turns the spotlight on this relatively new star of power electronics. Don’t hesitate to visit us at booth #947 and contact us to book meetings!

Discover today a power electronics review of Yole SystemPlus’ analysts.

Device design technologies on the table

In its reports, Yole SystemPlus analyzes the device design technologies currently available. The company compares up to 14 cross-sections of 1200 V transistors. Most players work on a planar process (onsemi, Wolfspeed, Microsemi…), and only two have chosen trench MOSFET (ROHM Semiconductor and Infineon), which is much more complex to design.  Other market leaders like ST Microelectronics and Mitsubishi also bet on the trench process, but with no success so far.

Yole SystemPlus digs deeper to reveal the evolution of the design strategies adopted by two leading players through three transistor generations. By switching from a planar (generation 2) to a trench process (generation 3), ROHM reduced the FoM (Figure of Merit, Rdson*Qg) and pitch size by 50% over only four years.  These results have been further improved using a more advanced trench process for the following generation. Meanwhile, Wolfspeed prefers to focus on a planar design with a Diffused MOS process that reduced the die size and FoM by 50% between the first and third generations. When comparing the two competitors’ latest generation transistors, it all comes down to pitch size reduction, for which RHOM’s trench version is well ahead.

However, this trench MOSFET is more complex and, therefore, more costly to manufacture. In addition, because the gate oxide thickness is more difficult to control with this design, areas of weakness in the gate trench may challenge component reliability.

Barriers to be considered

Although the figures and emerging M&A activity tend to show a growing interest in this composite, its expected position within power electronics will only be confirmed if solutions are found to the three main obstacles currently slowing the wider adoption of SiC.

  • Cost

To date, the cost of SiC modules does not offer the possibility of democratizing this technology on EVs other than at the high end. The industrial sector, which targets 3300 V for its high-power applications, is still reluctant to dive into SiC for the same reason and still relies on the Si IGBT option. From Yole SystemPlus’ analyses, the costs attributable to the substrate manufacturing and epitaxy stages include 59% of total wafer cost (on average for 1200 V SiC MOSFETs), followed by yield losses during the front-end process (24%). At the die ampere cost level, Wolfspeed and ROHM Semiconductor are faring best, confirming that control of the whole supply chain gives a distinct advantage over the competition. To lower the cost, several scenarios are being considered. The transition from 6” to 8” wafers led by Wolfspeed, II-IV Incorporated, now Coherent, and SiCrystal is underway. However, quality issues are still delaying the actual start-up, now expected in 2025. New emerging technologies engineered SiC substrates compatible with Si production lines, and wafer process innovations are also under development.

  • Reliability

Although integrated into commercialized car systems (Tesla and Lucid Air inverters / Toyota Mirai II boost converter), there is not enough evidence on the long-term reliability of SiC products. This is another argument contributing to the wait-and-see attitude of the industrial sector.

  • Packaging

To fully benefit from SiC technology advantages, suitable packaging solutions must be found. And therein lies the rub: while there is a wide range of proven choices in the case of Si IGBTs, packaging options for SiC MOSFETs are still in their infancy and exhibit only a few designs developed by Denso, Wolfspeed, and ST Microelectronics. These designs include high-temperature compatible and low-loss materials whether in the substrate (material with good thermal dissipation properties such as AlN and AMB-Si3N4), encapsulation (high-temperature epoxy or silicone gel), die attachment (such as silver sintering) or interconnections (with low inductance interconnections such as top Cu leadframe). Much remains to be done before standardized solutions can be provided.

Make sure to meet the Yole Intelligence and Yole SystemPlus power electronics team during APEC from 19 to 23 March). Visit us at the booth #947: More information here!

About the authors

Amine Allouche serves as a Technology & Cost Analyst, Power Electronics, at Yole SystemPlus, part of Yole Group.
With strong expertise in the field of power electronics, Amine produces reverse engineering & costing analyses while also working on custom projects. He collaborates closely with the laboratory team, and together they define the objectives of the analyses and determine the methodologies necessary to reveal the structure of a device and all materials required for its development and production. Amine’s aim is to determine the technology choices made by the leading companies.
In addition, Amine runs a daily technology watch to identify innovative power electronics components and related manufacturing processes. His objective is to gain a comprehensive understanding of the evolution of power electronics technologies and to identify the technological strategies of the leading players in this field.
Amine attends numerous international trade shows & conferences where he meets the power electronics companies and discovers the latest innovations. He also presents key results of his studies during webcasts.
Amine holds a master’s degree in Micro & Nanotechnologies with a focus on integrated systems from Grenoble’s Polytechnic Institute (France). He also graduated from the Ecole Polytechnique Fédérale de Lausanne (EPFL) (Lausanne, Switzerland) and the Politecnico di Torino (Italy).

Elena Barbarini is Director, Semiconductor Devices Department, at Yole SystemPlus, part of Yole Group (Yole). Based on extensive experience in the semiconductor industry, Elena manages the production of reverse engineering & costing reports and custom projects through a dedicated team of analysts. The semiconductor device experts daily investigate innovative semiconductor manufacturing processes to reveal the technology choices made by the leading semiconductor companies, determine the process flows, evaluate manufacturing costs, and describe the related supply chain. Elena is responsible for the development of the industrial and technical expertise of the semiconductor devices team. In parallel, Elena uses her industrial and technical knowledge to define Yole SystemPlus’s product’s strategy. She also collaborates with the laboratory team to identify objectives and set up relevant methodologies to implement comprehensive physical analysis. Elena manages the business relationship with key Yole SystemPlus customers, identifying their needs, responding to their queries and presenting results. Prior to Yole SystemPlus, Elena had relevant experience at Alten (France), Osai (Italy), Vishay (Italy) and IBN (Singapore) where she developed significant competency and know-how in semiconductor manufacturing and related equipment, business development, and activity diversification. With a power electronics background, Elena authored numerous reverse engineering & costing reports and presented numerous times at key international conferences, trade shows and webcasts. She also authored many scientific papers and articles for power electronics media. Elena holds a Ph.D. in Power Electronics Engineering and a master’s degree in Micro & Nanotechnologies with a focus on integrated systems from Politecnico di Torino (Italy). She also graduated from Ecole Polytechnique Fédérale de Lausanne (EPFL) (Lausanne, Switzerland) and Grenoble’s Polytechnic Institute (France).