ST Cements Leadership in SiC, Increases Focus on GaN

Article By : Stephen Las Marias

Apart from SiC, where STMicroelectronics has already built a strong momentum, the company is also increasing its focus on GaN.

Evidence shows that industrialization (starting from the industrial revolution all the way to our modern industrial processes) has significantly contributed to global warming. According to the World Economic Forum (WEF), while technological advances brought immense improvements, they came at the cost of burning fossil fuels—releasing significant amounts of carbon dioxide and other greenhouse gases to the Earth’s atmosphere.

The WEF adds that as globalization and trade progressed, people and goods began moving around more than ever before, driving industrialization to further intensify to meet the demands of a rising global population and the modern world.

In 2019, total worldwide electricity consumption reached around 23,000 TWh, according to the International Energy Agency (IEA). The industrial segment accounted for the majority or 42% of this overall consumption.

Considering this figure, according to Edoardo Merli, EVP & Power Transistor Sub-Group General Manager, ADG, at STMicroelectronics, a 1% efficiency improvement in the industrial sector will translate into a savings of 96.6 TWh.

“This means we can save the equivalent of 15 nuclear plants and save 32 million tons of CO2,” says Merli. This also equates to around 8 million tons or 55 million barrels of oil equivalent.

While the onus is on governments worldwide to enact sustainability policies and initiatives such as carbon emission reduction, the technology and industrial sectors can play a big part in creating innovations and developments that would help achieve targets such as the U.N. Global Compact’s Business Ambition for 1.5°C.

Power technologies are key

Sustainability is a mandate that STMicroelectronics had been adhering to for over 30 years.

Edoardo Merli

“Sustainability is engraved in our culture. We at ST have announced that we will be a sustainable company, a carbon neutral company, by 2027,” says Merli. “This is compliant to the targets set in Paris in 2021, to keep the warming increase within 1.5°C by 2025.”

And key to achieving such goals are power technologies. Merli says power technologies are critical to achieving better energy efficiencies, and innovation in this sector is key to supporting a sustainable future.

“New materials like silicon carbide (SiC) and gallium nitride (GaN) offer clear benefits compared to silicon technologies. They can afford high voltage resilience, achieve faster switching, operate in high temperatures, and then at the end, through lower conduction resistance, they can reduce the heat and power dissipation, allowing higher efficiencies and thereby energy savings,” says Merli.

Indeed, over the past few years, SiC and GaN technologies have been seeing increasing adoption in the semiconductor industry as end applications continue to demand higher and higher efficiencies in power devices.

According to market analyst Fact.MR, the global SiC and GaN power semiconductor market is estimated to reach $884 million in 2022, and demand is forecast to surpass $6.95 billion by 2032—registering a compound annual growth rate of 23% over the 2022–2032 forecast period.

SiC and GaN technologies offer clear advantages and benefits in every step of the overall power conversion chain—starting from energy generation, to transmission, distribution, storage, and conversion, and up to the final consumption of energy and the user of the application, according to Merli. They offer higher voltage capabilities, frequencies, and operating temperatures, as well as lower conduction resistance, thereby producing less heat, power dissipation, and as such, providing higher efficiencies.

The two have some differences that make them suitable for different types of applications. SiC operates at higher voltages than GaN, but it requires higher gate drive voltage. On the other hand, GaN switches faster but operates on a slightly lower voltage than SiC.

Between the two wide-bandgap devices, SiC has a bigger market share because improvements in the quality of SiC wafer substrates have resulted in the usage of bigger diameter wafers in recent years. As a result, high-current, low-cost devices have been created and are starting to be used in a variety of equipment, according to Fortune Business Insights.

“If you look at some industrial applications, such as power supply for servers and for data centers, this translates into higher efficiency, then at the end the reduction of total cost of ownership,” says Merli. “The same for a number of motor control automation for industrial applications, wherein the use of SiC enables more compact design, reduced size, and weight, and eventually the reduced total cost of ownership. It is the same for renewable energy, the solar plants, the windmills, and power stations for servers.”

EVs: Paradigm shift

“The electric vehicles [EVs] are really a big change,” says Merli. “It is a completely new paradigm. Of course, the emission is zero, efficiencies are much higher, it can work in a much lower temperature, and then we’re talking about much lower weight. From a certain perspective, EVs are simpler to manufacture than internal combustion engine-based vehicles. And this has led to a shakedown of the overall automotive industry and to the entry of new players coming from different domains.”

The growing adoption of EVs is expected to drive the SiC market growth. The US, for example, targets 50% EV sales by 2030. In fact, California requires that all new cars and passenger trucks sold by 2035 be zero-emission. The UK targets 37.5% EV market share by 2030, and 100% sales of zero-emission vehicles by 2035. In Asia, China is aiming for a 30% EV market share by 2025, and that automakers to make EVs 40% of all sales by 2030.

“Starting from 2020, the power technology powertrain actually accounted for 40% of the overall semiconductor technologies in the powertrain. By 2025, it would be more than 50%, and silicon carbide will be more than a quarter of this amount, starting from much lower presence in 2020,” says Merli.

ST is one of the pioneers of using SiC in powertrains. In fact, ST started 25 years ago when it was studying the technology in collaboration with the Physics Department of the Catania Power Electronics Center. Right now, the company has its Gen3 STPOWER SiC devices, most of which are in production.

“What we would like to underline here is that every time we move to the next technology, we’re improving the main figure of merits, and then we’re expanding the technologies, making them tailored against some specific applications and expanding the polar ranges,” explains Merli. “We have many product families and we’re readying more and more technologies and families in terms of voltages. The Gen3 has rated voltage ranging from 650V to 1200V; we also have higher voltage families— up to 2.2kV—for energy applications.”

ST currently accounts for 50% global market share of SiC MOSFETS. “If you look at only the automotive industry, we’re at 60%,” says Merli. “Our plan is to reach $1 billion revenue coming only from SiC—transistors, diodes, and power modules—by 2024. Today we’re really working with everyone, we’re working with all the OEMs in the automotive and in the industrial segment, all the Tier 1s, and we can count more than 90 projects where we have development and co-development partnership with the main actors there.”

The company is also now working on its Gen4 SiC devices. “We’re bringing to the market already the 4th generation. We’d be qualified within this year-end, and then we’d be deployed to the market,” says Merli. “Of course, we’re not working only on the SiC technology itself, but this is coupled with very deep and strong activity on the packages, because in order to exploit the best characteristics of SiC, and GaN as well, we do need to think about new packaging concepts and techniques.”

Merli notes that it is important to own as much as possible the overall manufacturing chain for new technologies such as SiC and GaN.

“And this is what we have done. We have completed our manufacturing chain by acquiring Norstel AB, which has been renamed to ST SiC AB now. We’re doing SiC substrates now, and we have plan to expand these plants. Together with the substrates, we have integrated our manufacturing chain, we have been expanding our manufacturing capability; in Catania, which is our main power fab, we have increased our capacity; in Singapore, we have doubled the line and we’re already preparing our transition from 6 inch to 8 inch,” explains Merli. “As far as the backend, we have our plants in Bouskoura, Morocco, and Shenzhen, China—which is our main plant for the packages.”

SiC is still a technology in its infancy, according to Merli, so there are still a lot of areas the company is working to improve. “Starting from the material—the wafer cost is still high,” says Merli. “But then, there are a number of techniques we’re working on, and other partners and companies are working on in order to improve that. Together with the substrate cost, we’re definitely looking at the epitaxy improvement, starting from the substrate.”

Focus on GaN

Apart from SiC, where ST has already built a strong momentum, the company is also increasing its focus on GaN. The company recently released its PowerGaN devices, which include the G-FET (650V D-MODE), a basic transistor in cascode configuration; G-DRIVE (650V D-MODE, for industrial applications only), a transistor coupled with a driver in the same package; and the G-HEMT (E-MODE), which is available in two models, 650V for the majority of the applications, as well as a 100V model for lower-voltage applications.

For its GaN devices, ST is mainly targeting the power adapter, server power supply, solar inverter, EV charging station, and on-board charger (OBC) and DC-DC applications in the automotive sectors. Merli notes that compared to conventional silicon solutions, their PowerGaN devices are around 4x smaller, 3x lighter, has 50% higher power density, and 20% lower power loss.

“The GaN market is starting to have quite a number of companies. Besides the big players in the market, there are the smaller companies and startups with good technologies,” says Merli. “What we are bringing to the market is all our power expertise and history. We can offer very integrated, optimized solutions coming from our overall expertise in terms of front-end, back-end, and integration. Besides that, we have a deep knowhow in power technologies, which can definitely help us in proposing and marketing in the best way possible. Finally, we have complete control of the manufacturing, which means a control of quality, volumes, and cost.”

ST recently announced acquisitions and partnerships to accelerate its GaN execution strategy. For one, the company has partnered with Taiwan Semiconductor Manufacturing Co. Ltd (TSMC) to leverage its foundry know-how and bring ST’s power GaN and GaN ICs to market faster. It also has acquired a majority stake in Exagan, whose expertise in epitaxy, product development, and application know-how will broaden and accelerate ST’s power GaN roadmap and business for automotive, industrial and consumer applications.

Bright outlook

Overall, the outlook for GaN and SiC devices continue to be positive, driven by their growing application in power management systems. In particular, the rising adoption of GaN and SiC power semiconductors in EVs is predicted to drive the market growth, according to Global Market Insights. Their advantages, such as higher power efficiency, high thermal conductivity, and reduced footprint, compared to traditional silicon-based power semiconductors, are resulting to their increased integration into OBCs, electronic control unit (ECUs), DC-DC converters, and traction inverters of EVs.

“SiC and GaN materials are allowing us and our users to reach higher efficiencies. As we have seen, the higher efficiency means savings in terms of dissipation and reaching the targets we want to achieve. We’re continuously investing in new technology and in manufacturing to be ready to cope with the big volumes that are already there but will increase,” concludes Merli.

 

Stephen Las Marias is the editor of EETimes Asia.

 

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