Innoscience Places Big Bet on GaN-on-Si
Innoscience Technology is hoping to make big waves in the Gallium Nitride (GaN) industry by fabricating 200mm (8") GaN-on-Si wafers and massively expanding their processing capacity.
GaN Industry Growing Quickly, but the Wafers Remain Small
In an industry analysis report released May 2021, Yole Développement forecast that the GaN market would grow rapidly in the coming years. Specifically, they estimated an astounding 86% CAGR from 2020 to 2026 for GaN-on-Si. Notably, the analysis stated “the transition to 6" is ongoing and expected to accelerate in the coming years.”
Considering that the silicon industry transitioned from 6” (150 mm) diameter wafers to 8” (200 mm) diameter wafers in the early 1990s, hearing that the GaN industry would be accelerating its transition to 6” sounds almost archaic. And, of course, the silicon industry has since moved on to 12” (300 mm) wafers for its highest volume manufacturing.
Silicon industry wafer diameter evolution. GaN remains primarily on 6" (150 mm) wafers. Image courtesy of Any Silicon
Manufacturing of wide bandgap materials like GaN has lagged well behind Si. Even today that manufacturing is done primarily on 4” and 6” wafers using older production tools. This has created a bit of a paradoxical problem. The demand for GaN has remained low because the costs are high due to those small wafers and the typically poorer yield on the older tools. And, without sufficient demand, there also wasn’t much investment to migrate GaN manufacturing to 8” wafers and help drive down those costs.
A Big Gamble on Bigger Wafers: 8” GaN-on-Si
For a company that is barely 6 years old and less than 3 years removed from its first volume production, Innoscience Technology is investing heavily in the Gallium Nitride (GaN) industry. EETech Media’s Director of Engineering, Dale Wilson, recently sat down with Dr. Denis Marcon, the General Manager for Innoscience Europe, to discuss their GaN e-HEMT technology and future plans.
In December of 2015, Innoscience was founded with the express goal of building GaN-on-Si 8” wafers. They were betting on both the technology and the market. For the technology, moving to 8” wafers would provide the obvious advantage of nearly 2X more die per wafer than 6” wafers. But, as noted by Marcon in our discussion, moving to 8” wafer manufacturing also allowed them to take advantage of the decades of advancements in wafer processing technology made by the silicon industry.
The silicon industry had already figured out how to maximize wafer throughput and yield while minimizing process variation. By investing in 200mm tools from leading manufacturers like ASML, Innoscience could improve both their throughput and yield. They were all in on GaN-on-Si at 8” when “the market was still hesitant on GaN.”
Today, Innoscience claims to be the world’s largest 8-inch Integrated Device Manufacturer (IDM) focused solely on GaN technology. Marcon stated that Innoscience currently has over 1400 employees and that over 300 of those are focused on R&D. But, likely due to a combination of being headquartered in Suzhou, China (near Shanghai) and the company’s youth, Innoscience Technology is still a relative unknown in the GaN industry. In an effort to expand their global presence, in January of 2022, they announced the addition of design and sales support facilities in Leuven, Belgium and Santa Clara, California.
Enhancement-Mode, Normally-Off GaN HEMTs for the Power Market
Most GaN high electron mobility transistors (HEMTs) are depletion-mode, normally-on devices. This means, unlike more familiar silicon transistors, they conduct current when the gate-to-source voltage is 0 V. A voltage must be applied to turn the device off. This is typically less desirable in circuit applications.
Innoscience is manufacturing enhancement-mode (E-mode) HEMTs. The normally-off operation is achieved by growing a p-type p-GaN layer on top of an AlGaN barrier layer, use of a metal gate, and a selective recessing of the p-GaN layer over the AlGaN barrier. The gate metal forms a Schottky contact with the p-GaN layer.
Cross-section of an enhancement-mode GaN HEMT. Image courtesy of Innoscience Technolgy.
Early Returns on the 8” GaN-on-Si Gamble
Innoscience reports that they currently have manufacturing capacity for 10,000 8” wafers per month, split almost evenly between their two fabs: 4,000 in Zhuhai and 6,000 in Suzhou. Marcon shared example data of their across-wafer and wafer-to-wafer uniformity. As they hoped, using the more advanced wafer processing tools is resulting in improved process control which ultimately means increased yields and lower costs.
Innoscience example data of across wafer variation for drain-source ON resistance. Image courtesy of Innoscience.
Innoscience example data of wafer-to-wafer uniformity for drain-source ON resistance. Image courtesy of Innoscience.
Big Dreams for a Big GaN-on-Si Manufacturing Facility
Innoscience plans to add another 40% to its total capacity this year. To meet this goal, the Suzhou fab will increase its capacity to 10,000 wafers per month. And that is just the beginning. They are planning additional expansion at Suzhou to increase total capacity to 70,000 8-inch wafers per month by 2025 - adding an additional 600% to their current manufacturing capability.
Innoscience Technology’s Current Suzhou Complex (left) and Planned Facility Expansion (right)
Innoscience is not alone in planning massive increases in semiconductor manufacturing in the coming years. But Marcon indicated that they already have tool delivery agreements in place that will allow them to meet those ambitious goals, even in these tight supply markets.
I asked Marcon if they continue to operate the smaller Zhuhai fab as the Suzhou fab eventually dwarfs its capacity. He replied that Innoscience plans to keep Zhuhai open with operations largely focused on R&D. Having the second, smaller fab will allow them to more effectively run process development without interfering with the high-volume production.
If You Build It, Will They Come?
It will be interesting to see if Innoscience’s big gamble on GaN pays off. They are counting on continued growth in power electronics operating at voltages from 30 to 650 V. Applications include data centers, electric vehicles (EVs), portable devices, mobile phones, and chargers. They will also face pressure from other GaN-on-Si manufacturers and competing technologies including GaN-on-SiC, GaAs, and, of course, silicon.
Featured image used courtesy of Innoscience Technology.