IMEC Achieves Record GaN Breakdown Voltage Above 800V Using Shin-Etsu Chemical’s 300-mm QST™ Substrate
Tokyo, Japan — Shin-Etsu Chemical Co., Ltd. (Head Office: Tokyo; President: Yasuhiko Saitoh) announced that its newly developed 300-mm QST™ substrate has been successfully adopted for IMEC’s 300-mm GaN power device development program. This milestone marks a major step forward in next-generation power device technology, with IMEC achieving a world-record breakdown voltage exceeding 800 V on a GaN HEMT device fabricated on the QST™ substrate—significantly surpassing the previous 650 V benchmark for 300-mm GaN-on-substrate devices.
1. Breakthrough in Large-Diameter GaN-on-QST™ Technology
The QST™ substrate—short for QROMIS Substrate Technology—is a proprietary 300-mm GaN growth substrate developed by Shin-Etsu Chemical under license from QROMIS, Inc. (Head Office: California, U.S.A.; CEO: Cem Basceri). The substrate enables the high-quality epitaxial growth of gallium nitride (GaN) films on large-diameter wafers, overcoming the limitations that have long hindered the scaling of GaN power devices.
In collaboration with QROMIS, Shin-Etsu Chemical currently manufactures 150-mm and 200-mm QST™ substrates, as well as GaN-on-QST™ epitaxial wafers in various diameters. Building on this foundation, the company began offering 300-mm QST™ sample substrates in September 2024 as part of a joint development initiative with QROMIS. This partnership aims to accelerate the commercialization of large-diameter GaN substrates for advanced power, RF, and optoelectronic applications.
2. IMEC’s 300-mm GaN Development Program
IMEC, a world-leading research and innovation center for nanoelectronics and digital technologies based in Leuven, Belgium, launched its 300-mm GaN power device program in October 2025. The initiative leverages IMEC’s state-of-the-art 300-mm CMOS fabrication line to develop next-generation GaN-based power devices with unprecedented performance and manufacturability.
The program’s goal is to demonstrate high-voltage, high-efficiency GaN power devices that can be produced on industry-standard 300-mm wafers. IMEC’s first milestone product—a 650 V-rated GaN HEMT (High Electron Mobility Transistor) fabricated on Shin-Etsu’s 300-mm QST™ substrate—has already surpassed expectations by achieving a breakdown voltage exceeding 800 V. Building on this achievement, IMEC plans to develop a 1200 V+ device in the next phase, targeting demanding applications such as AI data centers, industrial power conversion systems, and automotive power electronics.
3. Record-Breaking Device Performance
The record-breaking results were obtained through IMEC’s fabrication of a 5 µm-thick high-voltage GaN HEMT structure grown on Shin-Etsu’s 300-mm QST™ substrate. The GaN epitaxy was carried out using Aixtron’s Hyperion MOCVD system, which enables uniform deposition across large wafer areas compliant with SEMI 300-mm standards.
The resulting HEMT device demonstrated:
- Breakdown voltage exceeding 800 V, the highest value ever reported for a 300-mm GaN-on-substrate device.
- Excellent in-plane uniformity across the entire wafer.
- Stable, crack-free epitaxial growth, confirming the mechanical and thermal stability of the QST™ substrate.
This breakthrough demonstrates that the QST™ substrate, engineered with a thermal expansion coefficient closely matched to GaN, can sustain stress-free epitaxial growth even at large diameters—an achievement that has been a major challenge for GaN-on-silicon platforms.
4. Addressing Long-Standing Challenges in GaN Manufacturing
While GaN-on-silicon (GaN-on-Si) technology has enabled cost-effective manufacturing on existing silicon wafer production lines, it faces critical challenges at larger diameters. As wafer size increases, the mismatch in thermal expansion between GaN and silicon leads to severe wafer bowing, cracking, and yield loss, making 300-mm GaN-on-Si impractical for high-voltage or thick-film applications.
The 300-mm QST™ substrate effectively resolves these issues. Its unique composite structure enables the epitaxial growth of thick GaN films without wafer warpage or cracking, even under the thermal stress of high-temperature MOCVD processes. This capability allows manufacturers to leverage existing 300-mm silicon CMOS fabrication lines while realizing the performance advantages of GaN at a much lower cost per device.
The combination of mechanical stability, thermal compatibility, and scalability makes the QST™ platform an ideal choice for developing high-voltage GaN power devices. It paves the way for the mass production of 300-mm GaN wafers suitable for diverse applications, from power supplies and electric vehicles to next-generation AI data centers.
5. Strengthening Global Collaboration
Shin-Etsu Chemical and QROMIS have established a close strategic partnership to accelerate the commercialization of 300-mm QST™ substrates. Together, the two companies supply wafers to IMEC’s 300-mm CMOS facility, which serves as a collaborative hub for global semiconductor leaders. This partnership integrates material innovation, epitaxial process technology, and advanced device development, enabling a seamless path from R&D to mass production.
The QST™ substrate’s compatibility with standard silicon manufacturing lines also allows rapid integration into existing production ecosystems. This advantage not only reduces infrastructure investment but also enhances supply chain resilience and sustainability across the GaN device industry.
6. Toward Sustainable and Efficient Power Electronics
The achievement of an 800 V breakdown voltage on a 300-mm GaN-on-QST™ wafer represents a key milestone in the evolution of wide-bandgap semiconductors. It demonstrates that large-diameter GaN substrates can now deliver both high performance and manufacturability, opening the door to high-efficiency, compact, and cost-effective power devices.
Shin-Etsu Chemical continues to expand its production capabilities for 150-mm and 200-mm QST™ substrates, while actively preparing for the mass production of 300-mm QST™ wafers. The company’s long-term vision is to provide a full lineup of 150-mm, 200-mm, and 300-mm QST™ substrates to meet the growing demand for GaN devices in power electronics, high-frequency communications, and optoelectronics.
Currently, many domestic and international customers are evaluating QST™ substrates for use in power devices, RF amplifiers, and LED applications. With the rapid expansion of AI-driven data centers and the increasing need for energy-efficient power conversion, interest in GaN technologies continues to rise sharply worldwide.
7. Commitment to a Sustainable Future
Through continuous technological advancement and collaboration, Shin-Etsu Chemical is committed to promoting the social implementation of GaN-based devices—technologies that combine high energy efficiency, compactness, and environmental sustainability. By enabling scalable and reliable GaN manufacturing on 300-mm wafers, Shin-Etsu aims to contribute to the realization of a sustainable society where energy can be used more efficiently and responsibly.
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