Diamond Foundry Grows 200mm Diamond for AI Chips
Diamond Foundry says it has grown the world's first 200-millimetre single-crystal diamond, a development that could bring one of nature's most heat-conductive materials closer to semiconductor manufacturing.
The San Francisco company announced the milestone on 6 November 2026, describing it as the culmination of a 25-year effort to grow large, continuous diamond crystals. It showed the crystal, which it calls the D200mm, at the CarbonSemi 2026 conference in Ningbo, China, on 5 and 6 November.
The D200mm doubles the diameter of the 100mm single-crystal wafer Diamond Foundry announced in November 2023. The key word is single-crystal: the new disc has one continuous crystal structure, rather than a collection of smaller diamonds joined together or a polycrystalline disc made of many crystal grains. That distinction matters because grain boundaries can interfere with how efficiently heat and electrical charge move through a material.
The company's pitch is heat. Diamond is prized for its thermal conductivity, measured at approximately 2,000 watts per metre-kelvin, around five times the figure for copper. Diamond Foundry wants a thin layer of diamond sitting underneath AI chips, pulling heat away from processors that keep getting hotter as they pack more power into smaller spaces.
Modern AI processors concentrate substantial electrical power into very small areas. Localised heat buildup can limit performance, increase cooling requirements and speed up component wear. A diamond heat spreader or substrate in an advanced chip package could help move heat away from hot spots, and the material's wide bandgap of about 5.47 electron volts also makes it a candidate for high-power electronics.
The 200mm size is part of the strategy. At about eight inches across, the crystal matches the diameter of the 200mm silicon wafers still used for many power and analogue chips, so the material could in principle slot into existing manufacturing workflows rather than demanding custom tooling.
For now, though, the D200mm is a proof of scale, not a proof of production. The crystal on display is still as-grown and unpolished, and Diamond Foundry has not disclosed yield, defect density, cost or a date for commercial 200mm wafers. A raw crystal and a finished, fab-ready wafer are two different things, and the gap between them is where much of the engineering work still sits.
According to chief executive Martin Roscheisen, the achievement required advances in plasma physics, reactor engineering, growth chemistry, crystal engineering and manufacturing controls. He credited Stefan Gsell and Martin Fischer, whose work on scaling single-crystal diamond began 25 years ago and joined the company in 2022 through its acquisition of Germany's Augsburg Diamond Technology.
Diamond Foundry says the 200mm achievement makes a future 300mm crystal predictable, although it has not provided a timeline or detailed manufacturing data for that next step. The company is also developing a $2.77 billion large-scale production facility in Spain, a project tied to the EU Chips Act, as it tries to turn single-crystal diamond into an industrial semiconductor material.
Whether diamond becomes a mainstream chip material will depend on what comes next: polished wafers, published defect and yield data, and a chipmaker willing to test the substrate in real hardware. Until then, the D200mm shows that diamond can be grown at wafer scale, even if turning it into a product remains unfinished work.
