Boffins working for the Diamond Foundry have emerged from their smoke-filled labs claiming to have produced the world’s first 200mm single-crystal diamond. If it all pans out, they will have a way of giving chipmakers a new way to stop their increasingly powerful processors from cooking themselves.
According to Tom’s Hardware, the South San Francisco outfit unveiled the enormous laboratory-grown crystal at the CarbonSemi 2026 conference in Ningbo, China. Unlike the diamonds normally used to persuade someone to get married, this particular specimen is intended for the considerably less romantic business of removing heat from semiconductors.
The crystal measures 200mm across, matching the diameter of silicon wafers used in many semiconductor factories. More importantly, it consists of one continuous crystal structure rather than smaller crystals joined together. That distinction matters because boundaries between crystals can interfere with heat flow through a material.
Diamond is particularly attractive to chipmakers because its thermal conductivity is approximately 2,000 watts per metre-kelvin, compared with around 400 for copper. In theory, that makes it about five times better at conducting heat, although turning that advantage into cooler processors depends on how the material is integrated into a package.
Heat has become an increasingly expensive headache for semiconductor manufacturers. Modern processors pack billions of transistors into relatively small areas, generating concentrated hotspots that conventional cooling systems struggle to manage. The problem is especially acute for AI accelerators, where the industry seems determined to solve every computational problem by throwing more electricity at it.
Diamond could help spread that heat before it reaches the conventional cooling system. Its electrical insulating properties make it particularly interesting for semiconductor packaging, where engineers need to move heat away without accidentally creating electrical connections. The material’s exceptional hardness is less useful unless someone intends to beat a troublesome GPU into submission.
Diamond Foundry previously demonstrated a 100mm single-crystal diamond in 2023. Doubling the diameter to 200mm increases the theoretical surface area fourfold, giving engineers considerably more material to work with. Producing a single crystal at this scale is difficult because the growth process must maintain a consistent crystal structure across the entire surface.
The company’s work builds on approximately 25 years of research into growing large single-crystal diamonds. Diamond Foundry chief executive Martin Roscheisen credited hundreds of scientists, engineers and technicians with achieving the milestone, describing it as the product of decades of persistence.
Roscheisen believes the achievement opens a path towards producing 300mm single-crystal diamonds before 2030. That would bring the material into the size range used by modern advanced semiconductor manufacturing, although growing something that large without defects presents another collection of expensive engineering problems.
However, the 200mm diamond displayed by Diamond Foundry remains unpolished, meaning it has not yet been turned into a finished substrate suitable for semiconductor manufacturing. The company has shown it can grow a large crystal, but chipmakers need far more than something impressive to hold up at a conference.
Diamond Foundry has not disclosed manufacturing yields, defect densities or production costs for the new material. Those details will determine whether the technology can be produced commercially or whether it remains an impressive scientific demonstration with a price tag capable of frightening even the most enthusiastic chip executive.
Another problem is that existing semiconductor factories cannot simply replace silicon wafers with diamond and carry on manufacturing processors. Diamond has different material properties and processing requirements, while using it as a heat spreader introduces packaging challenges involving bonding, thermal interfaces and compatibility with existing manufacturing techniques.
Diamond Foundry has yet to announce a commercial production date or identify chipmakers adopting its 200mm crystals. For now, the company has shown that it can grow diamond at a diameter familiar to the semiconductor industry, while leaving the tricky questions of manufacturing cost and commercial availability unanswered.
