Diamond Thermal Conductivity: A New Era in Chip Cooling
14 comments
·October 21, 2025lorenzohess
kulahan
Fifty Celsius is an insane drop.
It sounds like the most important part of the article (and another cool quote) is this:
>Until recently we knew how to grow it only at circuit-slagging temperatures in excess of 1,000 °C.
So basically, the big breakthrough was low-temp growth of a diamond lattice. Very cool they can do it at such a low temperature. It must be a crazy low temp - probably under 100C?
modeless
If this can enable practically unlimited 3D stacking of CMOS layers, it could be hugely consequential for computing.
On an unrelated note, I like the writing style of this article a lot. This is how science journalism should be. It reminds me of how Scientific American used to be before it was ruined. Is IEEE Spectrum always like this? I might have to subscribe to the print version. I want articles like this floating around my house for my kids to discover.
greesil
Fun fact, diamond has 4x the thermal conductivity of copper.
chasil
Why not just use the diamond as the semiconductor?
https://www.powerelectronicsnews.com/diamond-semiconductors-...
Edit: Because they are polycrystalline, and produced with a very new and novel technology.
"Our diamonds are a polycrystalline coating no more than a couple of micrometers thick."
Symmetry
As the article you link says:
> The high p-n junction built-in voltage (4.9V, compared to 2.8V in SiC) and short carrier lifetimes limit the advantages of bipolar diamond devices to only ultra-high voltages (> 6kV) and low switching frequencies.
Nobody is thinking about using diamond for the silicon CMOS logic in a computer, though they may replace the gallium arsenide we use for motor control some day.
chasil
The author of the subject article goes on to relate:
"Before my lab turned to developing diamond as a heat-spreading material, we were working on it as a semiconductor. In its single-crystal form—like the kind on your finger—it has a wide bandgap and ability to withstand enormous electric fields. Single-crystalline diamond also offers some of the highest thermal conductivity recorded in any material, reaching 2,200 to 2,400 watts per meter per kelvin—roughly six times as conductive as copper. Polycrystalline diamond—an easier to make material—can approach these values when grown thick. Even in this form, it outperforms copper.
"As attractive as diamond transistors might be, I was keenly aware—based on my experience researching gallium nitride devices—of the long road ahead..."
DiabloD3
Fun fact: we already use diamonds in some thermal pastes, and they do perform pretty well, but not chart toppers.
_factor
“If our work continues to succeed as it has, heat will become a far less onerous constraint in CMOS and other electronics too.”
When it matures, you’re right back to the same heat constraint considerations, just with faster chips.
pfdietz
The article and paper don't mention it, but the thermal conductivity of single crystal diamond can be increased another 50% at room temperature by using pure carbon-12. The isotopic uniformity reduces scattering of phonons, which are what transports heat energy in diamond. For a very thin film like this the cost of using isotopically purified carbon shouldn't be that bad.
BTW, the thermal conductivity of C-12 diamond at cryogenic temperature is even higher, reaching something like 41000 W/m K at 104 K.
Isotopically purified silicon has also been considered due to its higher thermal conductivity, but the effect there at room temperature is not nearly as dramatic.
Weirdly, I read UV damage in C-12 diamond is reduced by a factor of 10 vs. natural diamond, I understand because this damage process is mediated by phonons. No relevance to the chip use case (unless UV damage in photolithography could be important?), but I found it interesting.
modeless
This is polycrystalline diamond, which probably scatters phonons anyway, so it seems naively like using a single isotope wouldn't help much. But that's definitely an interesting fact and I think you're right that it probably wouldn't add much expense when the amount of material is so small.
null
sunnypsyop
[dead]
Summary:
> Rather than allowing heat to build up, what if we could spread it out right from the start, inside the chip?... To do that, we’d have to introduce a highly thermally conductive material inside the IC, mere nanometers from the transistors, without messing up any of their very precise and sensitive properties. Enter an unexpected material—diamond.
> ... my research group at Stanford University has managed what seemed impossible. We can now grow a form of diamond suitable for spreading heat, directly atop semiconductor devices at low enough temperatures that even the most delicate interconnects inside advanced chips will survive... Our diamonds are a polycrystalline coating no more than a couple of micrometers thick.
> The potential benefits could be huge. In some of our earliest gallium-nitride radio-frequency transistors, the addition of diamond dropped the device temperature by more than 50 °C.