Shin-Etsu Chemical has announced that its 300-millimeter diameter QST substrate, designed for gallium nitride (GaN) epitaxial growth, is being used in IMEC’s 300-mm GaN power device development program. According to Shin-Etsu Chemical, evaluation of the substrate showed that a five-micrometer-thick high-electron-mobility transistor (HEMT) device built on the substrate achieved a voltage resistance exceeding 650 volts, and IMEC fabricated a structure surpassing 800 volts—setting new records for 300-mm GaN power devices.
The QST substrate is engineered to match the thermal expansion coefficient of GaN. This enables stable thick-film GaN growth on large-diameter substrates, overcoming warpage and cracking issues that have limited the use of silicon substrates for large-scale GaN devices. As a result, the QST platform allows for the fabrication of high-voltage GaN-on-QST devices in compliance with SEMI standards, using standard silicon wafer processing infrastructure, which Shin-Etsu Chemical claims will significantly reduce costs compared to traditional silicon-based methods.
Shin-Etsu Chemical reports that, in partnership with QROMIS, it began supplying 300-mm QST samples in September 2024 for IMEC’s 300-mm CMOS fabrication facility in Belgium. IMEC’s program officially launched in October 2025, initially developing a 650-volt device and planning to follow with a model rated above 1200 volts. Target applications specified include artificial intelligence (AI) data center power supplies, industrial systems, and automotive electronics. The devices were fabricated using Aixtron’s Hyperion metal-organic chemical vapor deposition (MOCVD) tool, which demonstrated high in-plane uniformity at the record voltage ratings.
Shin-Etsu Chemical is actively scaling up manufacturing for 150-mm, 200-mm, and 300-mm QST substrates, with current evaluations underway by domestic and international customers for high-voltage power device, high-frequency device, and LED applications. The company reports intensified demand from customers developing solutions for AI data center power infrastructure.
Source: Shin-Etsu Chemical
