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Shin-Etsu Chemical Co., Ltd. has announced a major development milestone for its QST™ substrate—a 300-mm GaN growth substrate—achieved through collaboration with IMEC.
The 300-mm QST™ substrate was adopted in IMEC’s recently launched 300-mm GaN power device development program. In initial evaluations, a 5 µm-thick HEMT (High Electron Mobility Transistor) structure fabricated on Shin-Etsu’s QST™ substrate demonstrated a record-breaking voltage resistance exceeding 800 V. This represents the highest breakdown voltage ever achieved on a 300-mm GaN substrate that complies with SEMI standards and confirms the substrate’s outstanding in-plane uniformity and crystal quality.
The QST™ substrate was developed by QROMIS, Inc., based in California, and licensed to Shin-Etsu Chemical. Shin-Etsu manufactures 150-mm, 200-mm, and 300-mm QST™ substrates, as well as GaN-on-QST™ epitaxial wafers. In September 2024, the company began offering 300-mm QST™ sample substrates in collaboration with QROMIS, strengthening its commitment to advancing large-diameter GaN manufacturing.
This partnership has enabled Shin-Etsu to supply QST™ substrates for IMEC’s CMOS-based 300-mm GaN fab. The joint program aims to develop both 650 V-rated and future 1200 V+ GaN power devices targeted for high-performance applications, including AI data centers, automotive systems, and industrial power electronics.
The QST™ substrate’s thermal expansion coefficient is closely matched to GaN, which facilitates stable crystal growth and reduces challenges such as wafer warpage that typically hinder high-yield GaN growth on silicon at larger diameters. By solving these limitations, the QST™ platform allows for the cost-effective production of thick-film GaN devices on 300-mm wafers—a key factor in scaling next-generation power semiconductors.
Manufacturing was carried out using Aixtron’s Hyperion MOCVD equipment, which enabled the precise deposition of the HEMT structure during testing. The results confirmed superior yield potential and mechanical integrity at the 300-mm scale, marking a crucial step toward practical large-scale manufacturing of GaN power devices.
Shin-Etsu is currently preparing for mass production of 300-mm QST™ substrates and has already enhanced its facilities for 150-mm and 200-mm variants. The QST™ substrate lineup, ranging from 150 mm to 300 mm, is being evaluated by domestic and international partners for applications in power conversion, RF, and LED markets, particularly in light of growing demand for high-efficiency systems in data centers and electric vehicles.
With its scalable GaN technology, Shin-Etsu aims to accelerate the adoption of GaN devices and support the shift toward more sustainable and energy-efficient technologies across the global electronics industry.
Original – Shin-Etsu Chemical
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Shin-Etsu Chemical Co., Ltd. has created a 300-mm (12-inch) QSTTM substrate, which is a substrate dedicated to GaN epitaxial growth, and recently started supplying samples.
Shin-Etsu Chemical has sold 150-mm (6-inch) and 200-mm (8-inch) QSTTM substrates and GaN on QSTTM epitaxial substrates of each diameter. Meanwhile, the company worked on further increasing the diameter in response to strong customer demand and successfully developed a 300-mm (12-inch) QSTTM substrate. GaN device manufacturers cannot benefit from increasing the diameter of materials because of the lack in large-diameter substrate suitable for GaN growth, despite the fact that they can use the existing Si production line for GaN.
This 300-mm QSTTM substrate enables GaN epitaxial growth without warping or cracks, which was unattainable on Si substrates, thus significantly reducing device costs. In addition to the enhancement of facilities for 150-mm and 200-mm QSTTM substrates already in progress, Shin-Etsu Chemical will work on mass-producing 300-mm QSTTM substrates.
Since QSTTM substrates have the same coefficient of thermal expansion as that of GaN, it is possible to constrain warping and cracks of GaN epitaxial layer on QSTTM substrate of the SEMI standard thickness. This substrate material allows for high-quality and thick GaN epitaxial growth with a large diameter. Leveraging this feature, many customers are evaluating QSTTM substrates and GaN on QSTTM epitaxial substrates for power devices, high-frequency devices, and LEDs. Despite the challenging business environment, customers have entered the development phase toward practical to address the recently increasing interest in power devices, including power supplies for data centers.
The addition of the 300-mm QSTTM substrate to the lineup of the 150-mm and 200-mm can significantly accelerate the spread of GaN devices. Shin-Etsu Chemical is committed to contribute to the realization of a sustainable society where energy can be used efficiently through the social implementation of GaN devices.
Original – Shin-Etsu Chemical
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OKI, in collaboration with Shin-Etsu Chemical Co., Ltd., has announced the successful development of a technology that uses OKI’s CFB (crystal film bonding) technology to lift off only the GaN (gallium nitride) functional layer from Shin-Etsu Chemical’s uniquely improved QST® (Qromis Substrate Technology) substrate and bond it to a different material substrate.
This technology enables the vertical conduction of GaN and is expected to contribute to the realization and commercialization of vertical GaN power devices capable of controlling large currents. The two companies will work further together to develop vertical GaN power devices that can be implemented in society by partnering with companies that manufacture these devices.
GaN devices are attracting attention as next-generation devices that combine high device characteristics with low power consumption, such as power devices that require high breakdown voltages of 1800 volts or more, high-frequency devices for Beyond5G, and high-brightness micro-LED displays.
In particular, vertical GaN power devices are expected to achieve significant demand growth as devices that can improve the basic performance of electric vehicles by endowing them with extended driving ranges and shortened power supply times. However, two major challenges hinder the social implementation of vertical GaN power devices: the diameter of the wafers must be increased to improve productivity and vertical conductivity must be realized to enable large current control.
The coefficient of thermal expansion of Shin-Etsu Chemical’s QST substrate is equivalent to that of GaN. It can suppress warpage and cracking. This characteristic enables the crystal growth of thick GaN films with high breakdown voltages even on wafers larger than 8 inches, thereby enabling the production of wafers with larger diameters.
On the other hand, OKI’s CFB technology can lift off only the GaN functional layer from the QST substrate while maintaining high device characteristics. The insulating buffer layer required for GaN crystal growth can be removed and bonded to various substrates via metal electrodes that allow ohmic contact.
Bonding of these functional layers to a conductive substrate with high heat dissipation will enable both high heat dissipation and vertical conductivity. Through this, the combined technologies of Shin-Etsu Chemical and OKI solve the above two major challenges, paving the way for the social implementation of vertical GaN power devices.
In the future, the two companies will contribute to the realization and widespread use of vertical GaN power devices through Shin-Etsu Chemical’s provision of QST substrates or GaN grown QST substrates to companies manufacturing GaN devices and OKI’s provision of CFB technology through partnering and licensing.
Furthermore, OKI hopes to use CFB technology to provide added value to semiconductor devices that go beyond the framework of single materials and help realize the company’s key message of “Delivering OK! to your life”.
Original – OKI
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Shin-Etsu Chemical Co., Ltd. has determined that QST® (Qromis Substrate Technology) substrate is an essential material for the social implementation of high-performance, energy-efficient GaN (gallium nitride) power devices, and the company will promote the development and launching on the market of these products.
Since QST® substrate is designed to have the same coefficient of thermal expansion (CTE) as GaN, it enables suppression of warpage and cracking of the GaN epitaxial layer and resultant large-diameter, high-quality thick GaN epitaxial growth. Taking advantage of these characteristics, it is expected to be applied to power devices and RF devices (5G and beyond 5G), which have been rapidly growing in recent years, as well as in such areas as MicroLED growth for MicroLED displays.
In addition to sales of QST® substrates, Shin-Etsu Chemical will also sell GaN grown QST® substrates upon customer request. We currently have a line-up of 6″ and 8″ diameter substrates, and we are working on 12″ diameter substrates. Since 2021, for each respective application for power devices, RF devices and LEDs, sample evaluation and device development are continuing with numerous customers in Japan and globally. Especially for power devices, continuous evaluation is underway for devices in the wide range of 650V to 1800V.
So far, Shin-Etsu Chemical has repeatedly made many improvements with regard to its QST® substrates. One example is the significant improvement in lowering defects originating from the bonding process, which has enabled the supply of high-quality QST® substrates. In addition, for the thicker GaN films that many of our customers have requested, we have promoted the provision of template substrates with optimized buffer layers, which enables our customers to realize stable epitaxial growth of more than 10 μm thickness. Furthermore, various successful results have been produced and reported on, including the achievement of thick-film GaN growth exceeding 20 μm using QST® substrates and the achievement of 1800V breakdown voltage in power devices.
Moreover, Shin-Etsu Chemical and Oki Electric Industry Co., Ltd. have jointly succeeded in developing a technology to exfoliate GaN from QST® substrates and bond it to substrates made of different materials using Crystal Film Bonding (CFB) technology. Until now, most GaN power devices have been lateral devices, but CFB technology takes advantage of the characteristics of QST® substrates to realize vertical power devices that can control large currents by exfoliating a thick layer of high-quality GaN from an insulating QST® substrate (see figure below).
To customers who manufacture GaN devices, Shin-Etsu Chemical will provide QST® substrates or GaN grown QST® substrates and Oki Electric Industry will provide its CFB technology through partnering or licensing. In this way, the two companies hope to contribute to the advancement of vertical power devices.
Based on these development results and also based on business situation inquiries from customers, Shin-Etsu Chemical will continue to increase production to meet customer demand.
Shin-Etsu Chemical will contribute to the realization of a sustainable society that can use energy efficiently by further promoting the social implementation of GaN devices that have characteristics that are absolutely essential for the future society.
Original – Shin-Etsu Chemical
