October 1, 2026 / SemiMedia / — Resonac Holdings has developed a 300mm, or 12-inch, single-crystal silicon carbide substrate, becoming the first Japanese company to demonstrate a SiC substrate at this diameter.

The SiC power semiconductor market currently relies largely on 150mm substrates, while 200mm production is gradually expanding. Because a 300mm wafer has roughly four times the surface area of a 150mm wafer, successful mass production could substantially increase the number of devices produced per substrate and improve manufacturing economics.

Scaling SiC to 300mm remains technically difficult. SiC crystal growth requires temperatures above 2,000°C, while the material's extreme hardness makes slicing and polishing more demanding. As substrate diameter increases, manufacturers must also control crystal defects, thickness variation, internal stress, warpage and cracking.

Resonac said its experience in commercial SiC substrate and epitaxial wafer production helped support the development, particularly in controlling recrystallization temperatures and internal stress during large-diameter processing. The company currently focuses mainly on 150mm substrates and is prioritizing expansion of its 200mm capacity.

Demand for SiC power devices is increasing across electric vehicles, energy storage, power infrastructure and AI data centers. Compared with conventional silicon devices, SiC can operate efficiently at higher voltages and temperatures while reducing switching and conduction losses in high-power conversion systems.

Competition in 300mm SiC is also increasing globally. China's SICC has previously announced development of a 300mm SiC substrate, while Wolfspeed produced a 300mm single-crystal substrate earlier this year. However, no supplier has yet established broad commercial production of 300mm SiC wafers.

Resonac said it will continue prioritizing 200mm products for now and evaluate future 300mm investment based on customer demand. The company believes the competitive landscape for 300mm SiC remains open and may invest if demand develops sufficiently to support an early market position.