Diamond Foundry grows a 200 mm single-crystal diamond

By Nathan Brooks

Diamond Foundry says it has grown the first single-crystal diamond measuring 200 mm in diameter, matching the standard diameter of many semiconductor wafers. The company announced the result on Nov. 6 during a video keynote by CEO Martin Roscheisen to the CarbonSemi 2026 conference in Ningbo, China.

What has Diamond Foundry actually shown?

The disc contains one continuous crystal rather than smaller diamonds joined together or a polycrystalline wafer. Photographs show the material as-grown and unpolished. Diamond Foundry disclosed no thickness, crystal quality, defect density, growth time, yield, cost or price.

Roscheisen said: “This is one of those milestones that once seemed almost impossible.” He credited Stefan Gsell and Martin Fischer, who have worked on scaling single-crystal diamond for 25 years. Roscheisen also said the result “makes D300mm predictable as well,” without giving a timeline for the 300 mm target.

The announcement establishes a geometry milestone, not commercial readiness. It provided no evidence that the material can enter volume chip processes, and it supplied no shipment or production-capacity figure. That distinction is less elegant than the photographs, but more useful to customers and process engineers.

Why does diamond interest AI-chip designers?

High-purity single-crystal diamond conducts heat at about 2,000 W/m·K at room temperature, several times the thermal conductivity of copper, the usual heat-spreader metal. AI accelerators concentrate more power into small hotspots. A diamond layer under or over a die can pull heat sideways before it reaches the cold plate.

Diamond Foundry describes that use for spreading heat from concentrated processor power. It also names high-power electronics, optics and quantum systems as target markets. Its larger commercial proposition is processing whole diamond wafers alongside silicon wafers, rather than fitting small diamond pieces into assembled systems.

Is the 200 mm disc a product?

No. The release concerns crystal growth and offers a route toward wafer-scale substrates, not a saleable component with published specifications. In November 2023, Diamond Foundry announced a 100 mm single-crystal wafer and named defect reduction as its next goal. The company has not yet published the data needed to compare the 200 mm crystal's quality with that earlier target.

Diamond Foundry says it is scaling volume production of chip substrates through a $2.77 billion project in Spain backed by the European Chips Act. The release named no site, timeline or capacity for that project. Thus, the $2.77 billion figure describes the stated project, while the 200 mm announcement provides no confirmed volume, revenue or shipment forecast.

Who is already selling diamond cooling?

Diamond heat spreaders already ship in smaller pieces. In February, Akash Systems said it had delivered Nvidia H200 servers fitted with its synthetic-diamond cooling to Indian cloud provider NxtGen AI. Akash claims the diamond moves heat about five times faster than copper.

In October, Frore Systems introduced LiquidJet Diamond, a cold plate with diamond placed over processor hotspots. Frore says the diamond adds up to 10°C of hotspot cooling, a figure from its own models. Neither company's performance claim has been independently benchmarked.

Diamond Foundry's case rests on scale: whole 200 mm crystals and eventually 300 mm crystals that could be processed alongside silicon wafers. It has yet to demonstrate that step with published quality data. A smaller heat spreader has reached an H200 server; the large, defect-controlled wafer remains the harder claim.

The next useful disclosure is production evidence: thickness, defect density, yield, cost and a 300 mm schedule. Until those numbers arrive, Diamond Foundry has shown the capability to grow a wafer-scale single crystal, not the economics or process control required to compete with copper and smaller diamond heat spreaders at volume.