Diamond Wafer to Cool AI Chips: Diamond Foundry Grows World's First 200mm Single-Crystal Diamond Wafer

US lab-grown diamond company Diamond Foundry says it has grown the world's first 200mm single-crystal diamond wafer, aimed at cooling AI processors whose heat now limits how fast they can run. Chief executive Martin Roscheisen revealed the result in a video keynote at the CarbonSemi 2026 conference in Ningbo, China, on November 5, and the company confirmed it in a press release on November 6. The wafer measures 200 millimetres across — about eight inches — matching the 200mm silicon wafers chip factories still use. (Archive image: a diamond wafer, illustrative.)

Diamond conducts heat about five times better than copper

Pure single-crystal diamond conducts heat at roughly 2,000 watts per metre-kelvin, about five times better than copper, while remaining an electrical insulator with a bandgap of about 5.5 electronvolts, so it can sit against a chip without shorting it. The company says AI accelerators now push past 1,000 watts per package and heat is becoming the bottleneck; bonding a thin diamond layer to a processor could pull heat away from hot spots, and the company also claims large gains in data-centre cooling efficiency and water savings — the company's own claims, not yet independently tested.

A materials milestone, not a product

The disc on show is as-grown and unpolished, and it still has to be sliced, polished and tested for flatness, defects and uniformity before a chipmaker could use it. The company has not disclosed yield, defect density, cost or a date for supplying customers. The new crystal, called D200mm, is twice the diameter of the 100mm single-crystal diamond, D100, the company announced in November 2023 — about four times the area. The company says a 300mm crystal is now foreseeable but has given no timeline.

Twenty-five years of work, and a plant in Spain

Roscheisen credited hundreds of engineers and scientists, in particular Stefan Gsell and Martin Fischer, who have worked on growing single-crystal diamond at scale for 25 years and joined the company in 2022 through its acquisition of Germany's Augsburg Diamond Technology. The company says it is scaling volume production of chip substrates through a $2.77 billion project in Spain backed by the EU Chips Act. Beyond cooling AI processors, diamond substrates could also let power electronics shrink without overheating.