Diamond Foundry Grows First 200mm Single-Crystal Diamond
The 8-inch crystal brings diamond to a chip-industry wafer size, a step toward cooling hot AI processors. But it is still unpolished, so how close are diamond wafers?
Hakkı ALKANPublished 3 min read
Diamond Foundry has grown the first single-crystal diamond measuring 200mm (about 8 inches) across, the San Francisco company said on November 5, 2026. The disc is one continuous crystal, not tiled pieces or polycrystalline diamond, and it puts diamond at the same diameter as the 200mm silicon wafers still used for many power and analog chips.
The sample is shown as grown and unpolished. The company has not shared yield, cost, defect data or a date for commercial 200mm wafers.
Image: Diamond Foundry
What did Diamond Foundry announce?
CEO Martin Roscheisen revealed the crystal in a video keynote at the CarbonSemi 2026 conference in Ningbo, China, and the company followed with a post on its website and a press release on November 6. Diamond Foundry calls it the first D200mm single-crystal diamond and says the result came from advances in plasma physics, reactor design and process control.
Roscheisen credited scientists Stefan Gsell and Martin Fischer, who have worked on scaling single-crystal diamond for 25 years and joined the company in 2022 through its acquisition of Germany's Augsburg Diamond Technology. "This is one of those milestones that once seemed almost impossible," Roscheisen said, adding that the result "makes D300mm predictable as well." No timeline was given for a 300mm crystal.
Why does Diamond Foundry want diamond in chips?
Heat is the main reason. Pure single-crystal diamond conducts heat at roughly 2,000 W/mK, about five times better than copper, so a thin layer bonded to a processor could pull heat away from hot spots. That matters as AI accelerators push past 1,000 watts per package and data centers spend more on cooling.
Diamond is also an electrical insulator with a bandgap of about 5.5 eV, against 1.1 eV for silicon and roughly 3.3 eV for silicon carbide. In theory that makes it suited to high-voltage and high-frequency power electronics, although reliable doping remains a hard problem.
Size has been the bottleneck. Chip plants are built around 200mm and 300mm wafers, and smaller substrates are harder to fit into existing production lines. The company previously showed a 100mm diamond wafer, so the new crystal doubles the diameter.
When could diamond wafers reach real products?
Not soon. The crystal still has to be sliced, polished and tested for flatness, defects and uniformity, and the process must be repeatable across many runs. Diamond Foundry says it is scaling volume production of chip substrates through a $2.77 billion project in Spain backed by the EU Chips Act, according to its November 6 press release.
The push comes as the chip industry looks for new materials and packaging tricks to keep AI hardware scaling, from stacked memory such as TSMC's 3D DRAM plans to better cooling. Demand from AI servers is already straining supply elsewhere, which is why RAM is so expensive in 2026.
For now, the 200mm Diamond Foundry crystal is a manufacturing milestone rather than a product. The next proof point will be finished 200mm wafers with published quality data.