The news about TSMC exiting the gallium nitride (GaN) foundry business has stunned the semiconductor industry, also laying the groundwork for integrated device manufacturers (IDMs) like Infineon Technologies to seize the moment and fill the vacuum.
Technology and trade media are abuzz with how GaN power device manufacturing is different from traditional power semiconductors, and how it doesn’t create strong demand for foundry services. Industry watchers are also pointing to the rising price pressure from Chinese GaN fabs as a driver for TSMC’s exit.
To offer clarity on this matter, EDN recently spoke with Johannes Schoiswohl, senior VP and GM of Business Line GaN Systems at Infineon. We began with asking how GaN manufacturing differs from mainstream silicon fabrication. “They are fundamentally not so different because we start with a silicon wafer and then grow epitaxy of GaN on top of it,” he said.
The dedicated epitaxial machines conduct the process of growing a GaN layer on top of a silicon substrate. “That’s the key difference,” Schoiswohl added. “From then onward, when GaN epi is grown, we use processes and tools similar to silicon fabrication.”
Figure 1 Johannes Schoiswohl explains the engineering know-how required in GaN fabrication. Source: Infineon
GaN’s journey to 300 mm
While China’s Innoscience claims to be the world’s largest 8-inch GaN IDM, operating a dedicated GaN-on-silicon facility, Infineon is hedging its bets on 300-mm GaN manufacturing. The German chipmaker plans to produce the first 300-mm GaN samples by the end of 2025 and kickstart volume manufacturing in 2026.
That will make Infineon the first semiconductor manufacturer to successfully develop 300-millimeter GaN power wafer technology within its existing high-volume manufacturing infrastructure. “We were able to move from 6-inch to 8-inch quickly and now to 300-mm because we could use the existing silicon equipment, and that’s beautiful from a capex perspective,” said Schoiswohl.
Figure 2 GaN production on 300-mm wafers is technically more advanced and significantly more efficient compared to established 200-mm wafers. Source: Infineon
What’s really new is the 300-mm epi tool, he added. “Moving to 300-mm fabrication is indeed challenging because there are a lot of engineering issues that need to be resolved,” Schoiswohl said. The GaN layer on top of the silicon layer has a different crystal structure, which causes a lot of strain and mismatch. Additionally, there could be a significant amount of wafer breakage. “It means that a lot of engineering know-how will go into the 300-mm GaN fabrication,” he said.
In a report published in Star Market Daily, Innoscience CEO Weiwei Luo acknowledged significant barriers that hinder the commercial realization of 12-inch or 300-mm GaN wafers. He especially mentioned the lack of metal-organic chemical vapor deposition (MOCVD) equipment capable of supporting 300-mm GaN epitaxy; MOCVD is the core equipment for the epitaxial growth of GaN layers.
Regarding MOVCD tools for 300-mm wafers, Schoiswohl acknowledged that Infineon is currently in the early stages. “We are working closely with MOCVD equipment vendors.”
GaN fabrication model
TSMC’s exit has raised questions about why the foundry model is losing traction in GaN. According to Innoscience CEO Luo, power GaN devices aren’t well-suited for the traditional foundry model because they require close coupling between design, epitaxy, process, and application. That’s where the foundry-client model struggles while the IDM model offers the agility and control.
Infineon’s Schoiswohl says that GaN manufacturing isn’t low margin, but what you need to do is ensure value creation. “First and foremost, you need to be cost-competitive,” he said. “You need to drive down costs aggressively, and for that, you must have a cost-effective manufacturing technology, which is 300-mm GaN wafers in this case.”
Second, IDMs like Infineon can innovate at the system level. “It’s not enough to simply develop a GaN transistor,” Schoiswohl said. “We need to have gate drivers and controllers and thus demonstrate how to create a system that offers maximum value.”
Figure 3 The system approach for GaN devices complements cost competitiveness. Source: Infineon
With optimized controllers and gate drivers, engineers can create GaN solutions that bring the system costs down. That makes GaN a meaningful and profitable business; however, this is far more challenging for a foundry than an IDM.
With 300-mm enablement and a focus on the system-level approach, Schoiswohl is confident that GaN can eventually reach cost parity with silicon. “The progress on product level triggers innovation on system level, where gate drivers and controller ICs are optimized for high-frequency implementations and new topologies.”
Future of GaN technology
While Infineon is doubling down on GaN manufacturing, Schoiswohl foresees massive advancements in the performance of GaN from a design standpoint. “We’ll see a huge drop in parasitic capacitance and on-state resistance in a given form factor.”
That, in turn, could harness the release of high-voltage bi-directional switches, where devices are analytically integrated into one die. You could turn it on and off in both directions, which enables a lot of new topologies.
With TSMC’s exit from the GaN fabrication business, will IDMs be the winners in this power electronics segment? Will GaN heavyweight Infineon be able to execute its 300-mm GaN roadmap as planned? Will other fabs follow suit after TSMC’s departure? These questions make the GaN turf a lot more fun to watch.
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