With tech companies racing to build more data centers housing servers that run the latest A.I. models, the amount of electricity these facilities consume is skyrocketing. But most of that electricity doesn’t power computing at all. It is squandered in the crudest way: as heat, spilling out of every one of the hundreds of billions of transistors in a modern chip.
“The dirty secret in chips is that more than half of all energy is wasted as leakage current at the transistor level,” said R. Martin Roscheisen, an electrical engineer and entrepreneur at Diamond Foundry, a company in South San Francisco that manufactures specialized diamonds for use in electronics.
This heat is a great waste of energy that significantly shortens a chip’s life and makes it run less efficiently, generating still more wasteful heat. Consequently, one of the critical tasks in data centers is keeping the temperature of servers down so they can run smoothly.
Mr. Roscheisen is one of many engineers developing ways to embed tiny pieces of synthetic diamond, of all things, into chips to keep them cool. Diamond, in addition to being the hardest known material, is also exceptionally good at moving heat from place to place.
“Most people do not realize that diamond has the best heat-conduction properties of any material,” said Paul May, a physical chemist at the University of Bristol in England. He added that diamond conducts heat several times faster than copper, a material often used in heat sinks for chips.
The high thermal conductivity of diamond arises from the same property that makes it so hard: Each carbon atom is bonded strongly to four neighbors, with no weak link in any direction. Those strong bonds are efficient at carrying the vibrations that move heat through a crystal.
“High-end electronics can already be bought that use diamond heat-spreaders,” Dr. May said. “Within a few years, even the processor in your home PC or mobile phone will probably be attached to a diamond heat-spreader.”
In recent years, Mr. Roscheisen’s company has been exploring how to make a thin layer of heat-dissipating diamond and attach it to the back of the silicon wafers on which chips are built. One selling point of this approach is that its thin diamond layers are made of single crystals, which are better at dissipating heat than arrays of crystals are. But such thin layers are harder to make, and consequently more expensive.
The company manufactures diamonds by making a very hot gas, or plasma, rich in carbon and coaxing it to deposit carbon atoms in precisely the right configuration. A key step, according to the company, is tricking each diamond to begin crystallizing as though it were growing atop a layer of existing, perfectly ordered diamond.
This effectively shows the new carbon atoms how to fit together. Proceeding without that instruction, the company’s website states, “is like 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 single, unified crystal.
After making the diamond disks, which are four inches wide, the company says that it uses patented techniques to smooth the diamond so flat that there is no defect larger than one atom above or below the entire surface of the wafer. Customers can then attach the flat diamond wafer to the bottom of their silicon-based chips.
The diamond layers “dissipate chip hot spots entirely,” Mr. Roscheisen said. “They’re effectively gone.”
“This approach could dramatically lower thermal resistance,” said Evelyn Wang, a mechanical engineer at M.I.T., but she noted that the technology has not yet been proven commercially.
Element Six, which is owned by De Beers, the diamond company, has long manufactured diamonds for industrial use and for cooling the chips used in powerful radio-communication devices, including communication satellites. Now it is marketing its diamonds for cooling computer chips.
“The thermal demands of next-generation A.I. and high-performance computing devices are driving renewed interest in advanced cooling solutions,” said Bruce Bolliger, the head of business development.
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 powerful new chips, Mr. Bolliger said, which could let them run faster, increase their lifetimes and decrease the cooling costs for data centers.
Srabanti Chowdhury, an electrical engineer at Stanford University, is using diamond to explore a new, more powerful kind of computer chip.
Historically, the main way to increase the speed of chips was to shrink transistors and cram more of them together on a flat silicon wafer. But chipmakers are running up against physical limits to how small they can make transistors. Researchers have tried to solve the problem by layering transistors on top of one another, but multiple layers produce even more heat.
Dr. Chowdhury’s group sought to siphon off heat using diamond layers made of many crystals, which are easier to manufacture 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.
Moreover, diamond is typically grown at temperatures over 1,300 degrees Fahrenheit, but that is far too hot for the silicon that serves as the chip’s foundation. When Dr. Chowdhury’s group tried to deposit diamond on silicon at a lower temperature, they had trouble getting the crystals to form correctly. “Every crystal that likes to grow at high temperatures, there are problems when you grow it at low temperatures,” she said.
The research is partly funded by DARPA, the research agency of the U.S. Department of Defense. “Pairing this low-temperature technology with other heat-removal approaches could unlock compute capabilities that aren’t currently feasible,” said Yogendra Joshi, a mechanical engineer at the Georgia Institute of Technology and a program manager at DARPA.
Dr. Chowdhury said that she and other researchers are trying to address a challenge that is both old and new. “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 said. “I have not seen anything that was so important so quickly.”
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