Diamond Foundry grows 200 mm diamond crystal for AI chip cooling
The world’s first 200mm single-crystal diamond, held outside Diamond Foundry’s headquarters in San Francisco (image: Diamond Foundry)
A diamond the size of a side plate has a potential destination far removed from a jeweller’s display: beneath the silicon of an AI processor. Diamond Foundry, a US synthetic diamond manufacturer, says it has grown a continuous single-crystal diamond 200 millimetres in diameter, extending a material prized for conducting heat to dimensions familiar to semiconductor manufacturers.
The development follows the company’s 100 mm single-crystal wafer announcement in 2023. Doubling the diameter provides four times the nominal surface area, offering more material from which to produce substrates.
How diamond heat spreaders could help cool AI chips
Diamond is exceptionally effective at conducting heat while also providing electrical insulation. With a thermal conductivity of up to 2,000 watts per metre-kelvin (roughly five times that of copper) it is well suited to managing the uneven heating of modern processors. Intense activity in specific regions creates localised hotspots that constrain operating speeds and accelerate wear, even when the chip's overall temperature remains low. Rapidly dispersing heat away from these dense zones reduces the thermal peaks that limit performance.
Diamond Foundry's approach to this is to thin the silicon and bond a layer of single-crystal diamond to the back of the chip, placing it close to the heat-generating transistors. This diamond layer spreads thermal energy sideways across a much wider area before it reaches the external cooling hardware, helping to bring down temperatures at the chip's hottest points.
Ultimately, diamond complements the broader cooling architecture, such as liquid-cooling loops, that removes heat from the system. Diamond Foundry's technical work even explores applying liquid coolant directly to diamond substrates, which could raise permissible operating power depending on the setup. However, the real-world performance of a finished chip depends on its entire thermal path, including the interfaces and bonds between different materials. Because of this, diamond's superior thermal conductivity does not automatically translate into a proportional boost in processor speed.
What the 200 mm crystal means for diamond wafer production
Harnessing this thermal potential on a broader scale requires material that can be processed into practical components. Semiconductor foundries rely on wafers; these are thin discs that allow thousands of devices to be manufactured simultaneously. While the 200 mm format is standard for analogue devices and sensors, advanced logic chips are typically produced on larger 300 mm wafers.
By achieving this established wafer diameter, Diamond Foundry has reached a major dimensional milestone. However, matching standard wafer sizes does not make diamond a direct drop-in replacement for silicon on existing production lines. Rather than forming a single processor-sized component, a large diamond wafer can be divided to supply multiple smaller substrates.
The material's continuous internal structure is equally vital. Single-crystal diamond features an uninterrupted, ordered atomic lattice throughout, whereas polycrystalline diamond consists of numerous crystal grains separated by microscopic boundaries. Although both forms have industrial applications, these structural differences significantly impact heat flow and how easily the material can be machined. Consequently, Diamond Foundry is focusing on single-crystal substrates designed for precision finishing and bonding directly beneath silicon chips.
Audiatec’s role in growing single-crystal diamond
Producing that ordered structure over a larger area has occupied researchers Stefan Gsell and Martin Fischer for 25 years, according to Diamond Foundry. The pair joined the company in 2022 following its acquisition of Germany's Augsburg Diamond Technology, known as Audiatec.
Their research tackled a fundamental obstacle: how to grow a large diamond without an equally large diamond surface to guide its formation. Carbon atoms must settle into a single, unified lattice; otherwise, independently growing regions can collide without their atomic structures aligning.
To solve this, Audiatec pioneered expertise in heteroepitaxy, in other words the process of growing a crystal on a different base material. Its specialised layered substrate provided an alternative foundation for diamond formation, allowing crystals to expand well beyond the limits of a traditional diamond seed. Diamond Foundry subsequently combined this breakthrough with its own plasma reactors and large-scale manufacturing capabilities.
The acquisition of Audiatec also bolstered a business model that spans both luxury jewellery and industrial materials. Founded in San Francisco in 2012, Diamond Foundry retails consumer jewellery through its VRAI brand while simultaneously developing substrates for advanced electronics. Its strategy places commercial wafer manufacturing directly alongside these consumer operations, with fully diamond-based semiconductor devices serving as a longer-term ambition.
Spain’s €2.35 billion diamond manufacturing programme
The industrial expansion includes a substantial commitment in Europe. In May 2026, Spain’s Ministry for Digital Transformation announced that the Spanish Society for Technological Transformation, or SETT, had formalised a €752 million investment in a joint venture with Diamond Foundry’s Spanish subsidiary and private investors.
The operation involves total planned investment of €2.35 billion through 2029, with SETT participating at 32%. Its public investment comes through PERTE Chip, Spain’s programme to strengthen microelectronics and semiconductor capabilities, financed through the national Recovery, Transformation and Resilience Plan.
The investment connects crystal growth in Trujillo, Extremadura, with wafer cutting, precision smoothing, polishing and inspection in Zaragoza. Trujillo will expand production of single-crystal diamond ingots, the larger bodies of material from which wafers are sliced, while Zaragoza prepares those slices for use as semiconductor substrates.
Together, larger crystal growth and this Spanish manufacturing hub tackle two interconnected barriers to adopting diamond more widely in electronics: producing it at practical dimensions and processing it into usable components. For AI chip designers, this clears a path toward harnessing diamond’s thermal properties inside the processor package, where controlling concentrated heat unlocks higher performance and a longer operating life.
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