Diamond Foundry 200mm wafer marks a major step toward bringing single-crystal diamond into mainstream semiconductor manufacturing. The San Francisco company announced on November 6, 2026 that it had created the first-ever D200mm single-crystal diamond, a continuous crystal measuring 200 millimetres in diameter. The milestone addresses one of the material’s longest-standing constraints, its limited size, and could support future heat-spreading substrates for advanced processors and other high-power electronics.
The announcement accompanied a keynote by CEO Martin Roscheisen, delivered by video at CarbonSemi 2026 in Ningbo, China. Diamond Foundry, founded in San Francisco in 2012, described the result as a fundamental advance in manufacturing diamond as a technology material at semiconductor-relevant scale. The company also said that single-crystal diamond has entered the wafer-scale era.
Diamond Foundry 200mm wafer: A continuous crystal, not a joined disk
The central technical distinction is that the D200mm sample is one continuous crystal. It is not an assembly of individual diamond pieces, and it is not a polycrystalline wafer containing multiple crystal grains. That matters because a continuous, ordered lattice is intended to preserve diamond’s combination of high thermal conductivity and electrical insulation without the grain boundaries found in a polycrystalline material.
Growing a single crystal across the full 200 millimetre diameter required Diamond Foundry to overcome challenges in crystal growth, plasma physics, reactor engineering, materials science, process control and manufacturing. The company said the achievement involved advances across those disciplines, rather than a simple increase in the size of an established production routine. Hundreds of engineers, scientists and technicians contributed over more than a decade.
The scale doubles Diamond Foundry’s previously announced 100 millimetre single-crystal diamond, which measures 3.9 inches. The new crystal measures 7.9 inches, roughly the wafer size used for older semiconductor processes. Diamond Foundry said the result also makes a D300mm single-crystal wafer predictable, with that larger size thought possible before 2030.
Why 300 millimetres matters
A 300 millimetre wafer would measure 11.8 inches, matching the size used in leading node processes. That comparison gives the D200mm result practical significance. Single-crystal diamond has attractive thermal and electrical characteristics, but its use in advanced electronics has been constrained by the difficulty of producing large pieces with consistent properties.
The company believes the new crystal changes that equation. Diamond Foundry is trying to turn a material historically available in small, scarce dimensions into an industrial semiconductor substrate. Roscheisen said the D200mm achievement is not an endpoint, but the beginning of a new manufacturing era for diamond. He also said the result makes D300mm predictable as well.
The larger objective is heat management. Diamond Foundry said modern AI processors concentrate large amounts of power into microscopic regions of silicon, creating increasingly severe thermal constraints. A diamond heat spreader or substrate could move heat away from hotspots and open possibilities for chip architectures, power density, reliability and cooling. The company is developing single-crystal diamond for semiconductor and advanced-technology applications that require more than conventional materials can provide.
Thermal performance with electrical insulation
Diamond’s appeal comes from a rare combination of properties. Its thermal conductivity is estimated at least five times that of copper, while high-purity single-crystal diamond conducts heat at roughly 2,000 watts per meter-kelvin at room temperature. At the same time, diamond retains electrical insulating properties. That makes it different from conductive metals that may assist with heat removal but can create electrical complications in advanced device designs.
For chipmakers, however, the material’s headline numbers do not establish manufacturing readiness. A thermal advantage only becomes commercially relevant if the substrate can be processed consistently and integrated with devices without introducing unacceptable defects. The first sample shown by Diamond Foundry remains unpolished and was grown directly from the growth process. It therefore still requires further processing and characterization before its suitability for chip manufacturing can be established.
Interesting Engineering reported that manufacturers must achieve consistent thickness, surface flatness and low defect density across the usable area. They must also confirm reliable electrical and thermal properties, demonstrate repeatability across multiple production runs and establish that the material can be integrated into device fabrication. Diamond Foundry has not yet supplied those manufacturing details.
A long scientific pursuit
The underlying work began 25 years ago with Stefan Gsell and Martin Fischer. Diamond Foundry said they pursued the scientific and engineering challenge of growing high-quality single-crystal diamond at scalable sizes, joining the company in 2022 through its acquisition of Augsburg Diamond Technology, known as Audiatec. Their crystal-growth expertise was combined with Diamond Foundry’s reactor technology and manufacturing capabilities.
Roscheisen said, “This is one of those milestones that once seemed almost impossible.” He also said hundreds of company personnel contributed through “countless experiments, failures, inventions, rebuilt machines, and insights over more than a decade.” In a separate comment, Roscheisen said, “Stefan and Martin pursued this goal for 25 years.”
He added that they continued when the prevailing view held that single-crystal diamond simply could not be made at this scale. Roscheisen said their perseverance now shows in the first-ever D200mm single-crystal diamond and makes D300mm predictable as well. The milestone is therefore both a materials achievement and a signal about the time required to turn difficult laboratory science into repeatable industrial output.
Process details remain important
Diamond Foundry’s earlier 100 millimetre crystal was produced using diamond heteroepitaxy, a technique that grows a crystal on a different underlying material while encouraging an ordered diamond lattice. The company has not disclosed whether the newly announced 200 millimetre crystal uses the same process. That unanswered detail matters because industrial adoption would depend on proving that performance, size and yield can be reproduced beyond a single sample.
The company also said it is scaling volume production of chip substrates through a 2.77 billion dollar European Chips Act project in Spain. That investment signals Diamond Foundry’s longer-term ambition to move beyond demonstration crystals. The immediate achievement is nevertheless clear: the company has moved single-crystal diamond into a diameter associated with established semiconductor manufacturing.
What the milestone means for chip cooling
For the AI hardware market, the Diamond Foundry 200mm wafer is significant less as an immediate product announcement than as a supply and scale signal. Larger continuous crystals could make diamond more practical for advanced chip packaging, heat spreaders and power electronics. The potential benefit is especially relevant as processors place more power into smaller areas and conventional cooling systems face rising thermal loads.
Commercial adoption still depends on work beyond the growth stage. The unpolished sample must become a finished wafer with consistent physical and electrical characteristics, and the company must show that it can reproduce results at production volumes. The company’s claim that D300mm is now predictable points toward those goals, while the absence of a disclosed production timeline keeps the commercial forecast provisional.
Still, the technical barrier has visibly moved. Diamond Foundry has produced a one-piece 200 millimetre crystal, twice the diameter of its prior 100 millimetre achievement, and has done so in a size roughly familiar to semiconductor fabs using older processes. If further processing proves repeatable, the Diamond Foundry 200mm wafer could serve as the foundation for diamond substrates intended to manage the heat density of advanced processors and other demanding electronics.