Power GaN and SiC: Entering a New Era

Article By : Maurizio Di Paolo Emilio 

Yole Développement estimated a general view of wide bandgap materials such as Gallium Nitride and Silicon Carbide...

Power electronics has taken an interesting road with the adoption of GaN and SiC. Yole Développement (Yole) estimated a general view of these wide bandgap materials. While silicon is still dominating the market, GaN and SiC devices are already more efficient solutions in some applications. From a development standpoint, SiC research  is focused on SiC wafer quality on larger diameters and power module development. In the GaN field, the main trends are on GaN device integration — either system-in-package or system-on-chip solutions.

Silicon carbide
Ezgi Dogmus, technology & market analyst at Yole, described the progress in wafer sizes used in processing SiC circuitry.“ We have seen a transition from four inches to six inches in the last couple of years. And now more and more device manufacturers are working on six inches. What we understand is that today the high quality six-inch wafers are still difficult to produce. This is still challenging in terms of substrate growth and also preparation, and this will directly affect the yield that you have in the next processes. So the idea for the device manufacturers is to start with good material from the beginning to the end, in order to really maximize their yield and also, of course, economize in terms of cost of their product,” Dogmus said.

She continued, “We have seen lots of investment from leading players such as Cree, II-VI and Sicrystal and also Chinese players. There has been a lot of involvement from many players in this area. Multiple-years supply agreements have been signed between substrate suppliers Cree/Wolfspeed and SiCrystal and device manufacturers such as Infineon and ST Microelectronics.”

ON Semi similarly entered a long term deal with a fab to demonstrate it can support high-volume markets. Most of these deals were signed between 2018 and 2019.

Figure 1: Power SiC long-term evolution (Source: Yole)
Figure 1: Power SiC long-term evolution. Click to enlarge the image. (Source: Yole)

“We know that ST has a partnership with Tesla for the silicon carbide main inverter, so it really represents the highest volume in the silicon carbide market today. And we also see Infineon and ON semi in the race, so they’re also really targeting industrial and automotive applications,” said Dogmus.

“ON Semi is also developing its internal silicon carbide substrates. They have also had an agreement with GTAT for the silicon carbide crystal supplies. It is essential to have high quality for them and also vertically integrate them into the supply chain and have the overall control on their material,” Dogmus said.

She continued, “We think that, looking into the future, the players will focus  more and more on the module part because we are going to target applications such as the high power applications, such as the main inverter and the charging infrastructure, and all these applications will also require high power modules.”

Gallium nitride
In the power GaN industry, one of the main trends has been to collaborate with established foundries such as Taiwan Semiconductor Manufacturing Company (TSMC), X-Fab, or Episil Technologies.

Power GaN ICs are sold largely into the consumer electronics market, mainly for fast chargers. And we have seen a lot of integration for these devices. “It’s an obvious technological trend for the consumer market. So, we have GaN system-in-package and GaN system-on-chip. These are the main solutions that are being offered now for fast chargers,” said Ahmed Ben Slimane, technology & market analyst at Yole.

Figure 2: Power GaN long-term evolution (Source: Yole)
Figure 2: Power GaN long-term evolution. Click to enlarge the image (Source: Yole)

He continued, “The requirement for fast charger, for example, is power density and efficiency. So, we have to really squeeze the system in this form factor and to lower the price per power. We have seen a big adoption for fast chargers mainly coming from Chinese OEMs for suppliers such as Navitas and Power Integrations.”

When dealing with substrates,  we have two: silicon and sapphire. GaN on silicon is being developed mainly on six-inch wafers, though some grow it on eight-inch wafers.

“We will still see GaN-based discrete devices, but it’s more suitable for high power applications for example in the data center or the power supply for base stations,” said Ben Slimane.

In the RF GaN domain, “Huawei already adopted gallium nitride power amplifiers in its 4G LTE base stations several years ago. And then with the arrival of 5G, we also have to go to higher frequencies beyond 3GHz. Still, we call them sub six gigahertz. Gallium nitride has even more and more potential because, at high frequency, the power density is still excellent compared to the LDMOS, and the power added efficiency also follows,” added Dogmus.

Figure 3: Power GaN Market (Source: Yole)
Figure 3: Power GaN Market. Click to enlarge the image (Source: Yole)

The adoption of GaN technology will have a good relevance in the 5G sub-ghz with particular attention to its use in high power base stations, but also in new active antenna systems. In the latter case the idea is to use low power active antennas but with many more antennas requiring various power amplifiers. One parameter to consider is power efficiency.

Power efficiency is an essential parameter in the RF domain for an amplifier, because it will tell you how much it will heat, how much you will lose in terms of thermal dissipation.

“By replacing the silicon technology with GaN, we were relying on the efficiency of the game to provide a much faster switching, also in terms of volume reduction for the power supply in itself. So, you can increase the data center capacity, which is very significant in the case of GaN devices,” said Ezgi.

“For the adoption of gallium nitride for the data centers, as of today we see a slow ramp adoption; this is because of the lack of regulations. So, there is a need from government to impose stringent regulations on data centers to reduce power consumption; then we will be able to see a higher penetration  in this application, said Ahmed

As high efficiency requirements increase, gallium nitride will indeed play an important role compared to silicon, which is still meeting current requirements.There has been significant development activity on full SiC modules, with a special focus on packaging materials such as die attach and substrate interconnections.

The packaging of power modules must be suitable, adapted to silicon carbide devices. In order to meet 100% silicon carbide requirements, a new type of packaging must be developed in which you can really benefit from high temperature operation, high frequency switching and so on.

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