The escalating demand for data centers to power advanced AI models is leading to a massive increase in electricity consumption. However, a significant portion of this energy isn’t used for computing; it’s lost as heat, generated by billions of transistors within each modern chip.
R. Martin Roscheisen, an electrical engineer and entrepreneur at Diamond Foundry, a company specializing in diamonds for electronics, reveals a “dirty secret” in the chip industry: “more than half of all energy is wasted as leakage current at the transistor level.” This excessive heat not only squanders energy but also drastically reduces a chip’s lifespan and efficiency, creating a vicious cycle of more heat. Consequently, a primary challenge for data centers is effectively managing server temperatures to ensure optimal performance.
Roscheisen is among many engineers exploring the integration of tiny synthetic diamond components into chips to combat this heat. Diamonds, renowned for their unparalleled hardness, also possess exceptional thermal conductivity. Paul May, a physical chemist from the University of Bristol, notes that “Most people do not realize that diamond has the best heat-conduction properties of any material.” He explains that diamonds transfer heat several times faster than copper, a commonly used material in chip heat sinks. The remarkable thermal conductivity of diamonds stems from their robust atomic structure: each carbon atom is strongly bonded to four neighbors, creating an efficient pathway for heat-carrying vibrations through the crystal.
“High-end electronics can already be bought that use diamond heat-spreaders,” Dr. May stated, predicting that “Within a few years, even the processor in your home PC or mobile phone will probably be attached to a diamond heat-spreader.”
Diamond Foundry has been working on developing ultra-thin layers of heat-dissipating diamond to be affixed to the back of silicon wafers used in chips. A key advantage of their approach lies in creating single-crystal diamond layers, which offer superior heat dissipation compared to polycrystalline arrays, though they are more challenging and expensive to produce.
The company’s method involves creating a superheated carbon-rich plasma, then carefully guiding carbon atoms to deposit in the precise crystalline configuration. A crucial step, as described on their website, is to “trick” each new diamond into crystallizing as if it were growing on an existing, perfectly ordered diamond layer. This effectively provides a blueprint for new carbon atoms to align correctly. Without this guidance, “multiple people trying to tile a floor from different ends of a room without using a template: They would meet somewhere in the middle without fitting” into a seamless, single crystal.
After producing four-inch-wide diamond disks, the company employs patented techniques to smooth the diamond to an atomic flatness, ensuring no defect larger than a single atom across the entire wafer surface. These pristine diamond wafers can then be attached to the underside of silicon-based chips.
Mr. Roscheisen asserts that these diamond layers effectively “dissipate chip hot spots entirely. They’re effectively gone.” Evelyn Wang, a mechanical engineer at M.I.T., acknowledges the dramatic potential for lowering thermal resistance with this approach but cautions that its commercial viability is still unproven.
Meanwhile, Element Six, a subsidiary of the renowned diamond company De Beers, has a long history of manufacturing industrial diamonds, including those used for cooling chips in powerful radio-communication devices like satellites. Now, they are extending their expertise to cooling general computer chips. Bruce Bolliger, head of business development, states that “The thermal demands of next-generation A.I. and high-performance computing devices are driving renewed interest in advanced cooling solutions.”
In January, the company announced a new material, a hybrid of diamond and copper intended to channel heat better than copper alone while being cheaper than diamond. “Copper-diamond composite provides an optimal thermal management solution” for high-performance chips, Mr. Bolliger said, which could let them run faster, extending their operational life, and reducing data center cooling expenses.
At Stanford University, electrical engineer Srabanti Chowdhury is leveraging diamond technology to develop a new generation of even more powerful computer chips. Traditionally, chip speed was boosted by shrinking transistors and packing more onto a silicon wafer. However, chipmakers are reaching fundamental physical limits for transistor miniaturization. While layering transistors offers a potential workaround, this method exacerbates the heat problem.
Dr. Chowdhury’s team is working to manage heat using polycrystalline diamond layers, which are simpler to produce than single crystals. But they faced obstacles. Usually in polycrystalline diamond layers, the crystals are oriented vertically and not so good at moving heat horizontally, which is the major requirement in chips, because chips are flat and wide.
Furthermore, diamonds usually grow at temperatures exceeding 1,300 degrees Fahrenheit, a temperature far too high for a silicon foundation. When Dr. Chowdhury’s group attempted lower-temperature diamond deposition on silicon, they struggled with correct crystal formation. “Every crystal that likes to grow at high temperatures, there are problems when you grow it at low temperatures,” she noted.
This research receives partial funding from DARPA, the U.S. Department of Defense’s research agency. Yogendra Joshi, a mechanical engineer at the Georgia Institute of Technology and a DARPA program manager, believes that “Pairing this low-temperature technology with other heat-removal approaches could unlock compute capabilities that aren’t currently feasible.”
Dr. Chowdhury observes that the challenge of heat dissipation is both long-standing and rapidly intensifying. “The problem of heat was already there, but now that the growth really came with A.I., it’s like a hockey stick — we see this problem growing very big,” she commented. “I have not seen anything that was so important so quickly.”