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Existing processors could get a boost from swapping silicon for carbon nanotubes

By mongeese · 11 replies
Aug 31, 2019
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  1. Truthfully, it has been some time since Moore’s law, the propensity for processors to double in transistor count every two years, has been entirely accurate. The fundamental properties of silicon are beginning to limit development and will significantly curtail future performance gains, yet with 50 years and billions invested, it seems preposterous that any ‘beyond-silicon’ technology could power the computers of tomorrow. And yet, Nano might do just that, by harnessing its ability to be designed and built like a regular silicon wafer, while using carbon to net theoretical triple performance at one-third the power.

    Nano began life much like all processors, a 150mm wafer with a pattern carved out of it by a regular chip fab. Dipped into a solution of carbon nanotubes bound together like microscopic spaghetti, it re-emerged with its semi-conductive carbon nanotubes stuck in the pattern of transistors and logic gates already etched on it. It then undergoes a process called ‘RINSE,’ removal of incubated nanotubes through selective exfoliation, by being coated with a polymer then dipped in a solvent. This has the effect of reducing the CNT layer to being just one tube, removing the large clumps of CNTs that stick together over 250 times more effectively than previous methods.

    One of the challenges facing CNT processors has been difficulty in separating N-type and P-type transistors, which are “on” for 1 bit and “off” for 0 bit and the reverse, respectively. The difference is important for binary computing, and to perfect it, the researchers introduced ‘MIXED,’ metal interface engineering crossed with electrostatic doping. Occurring after RINSE, small platinum or titanium components are added to each transistor, then the wafer is coated in an oxide which acts as a sealant, improving performance. After that, Nano was just about done.

    Part of Nano’s brilliance is its ability to overcome the intrinsic flaws of manufacturing CNTs, which had been a roadblock to researchers previously. A very small portion of CNTs have a high concentration of conductive metal impurities that force the transistor to be always on or always off, which has a cascading effect that can cripple the whole processor. The theoretical purity required to prevent this is 99.999999%; clearly unachievable; and thus the researchers invented ‘DREAM,’ designing resiliency against metallic CNT.

    Researchers observed that though one impure CNT might ruin one logic gate, if employed in a certain way in another, it can be harmless. They crafted software to predict when impure CNTs would cause the least damage, and they designed Nano with this resilient architecture. “The ‘DREAM’ pun is very much intended, because it’s the dream solution,” says Max Shulaker, co-author. “This allows us to buy carbon nanotubes off the shelf [with 99.99% purity], drop them onto a wafer, and just build our circuit like normal, without doing anything else special.”

    As Nano had its wafer constructed by equipment normally used for regular silicon processors, runs the open-source RISC-V instruction set, and was designed using publicly available Bluespec software, there appears to be little preventing it from being scaled up. DARPA, who supported the research, have already begun to implement Nano’s manufacturing techniques at an experimental fab. “We think it’s no longer a question of if, but when,” Shulaker said, adding that CNT products could appear on shelves in as few as five years.

    Image Credit: Laura Ockel on Unsplash

    Modern microprocessor built from complementary carbon nanotube transistors, Nature (August 2019)

    Permalink to story.

  2. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,639   +1,233

    Carbon Nanotechnology is the answer to everything.

    As soon as I get a nanosuit I’ll show NYPD who’s boss.
  3. noel24

    noel24 TS Evangelist Posts: 533   +472

    Omni Consumer Products will probably beat You to It.
    Dead or alive, You're coming with Them...
  4. Hoveringgoat

    Hoveringgoat TS Rookie

    Triple the performance at a third the pow usage? Does that mean 9 times the performance at a similar power level, I would assume not. Guessing it's two separate metrics that are being bundling in together. Should just state one or the other - they essentially are the same thing.
  5. mongeese

    mongeese TS Addict Topic Starter Posts: 268   +23

    Yes, it does imply CNT processors have nine times better performance per watt, but presently, it seems that they are most efficient at one-third power, so you can't ram them with electricity and get nine times the peak performance.
  6. VitalyT

    VitalyT Russ-Puss Posts: 4,612   +3,222

    I wonder if this new tech improves on EMP resilience, 'cos if it could, it would be a big plus.
  7. texasrattler

    texasrattler TS Evangelist Posts: 749   +299

    5 years? Most wont even remember 5 secs ago.
    The market will have something cool or newer by then n ppl will have long forgot about something that should have happened 5 yrs ago.
    Funded by Darpa, goodluck ever seeing this on the consumer market in our lifetime.
  8. Uncle Al

    Uncle Al TS Evangelist Posts: 5,716   +4,048

    Just hoping I live long enough to see it! And enjoy it!
  9. Markoni35

    Markoni35 TS Addict Posts: 325   +137

    Carbon nanotech is nowhere. I'm listening to the same old hollow story for the last 25 years. "Carbon nanotubes this, carbon nanotubes that" but nothing really works.
    Why don't they just switch to germanium? It's faster than silicon, the chips could reach 7 GHz without problems. You know it's gonna be faster and more accurate, it's got "German" in its name :)
  10. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,639   +1,233

    Carbon fiber has extensive use in automobiles right now.
    From that alone we can see the strength and weight savings from Carbon Fiber Wheels and Carbon Fiber driveshafts. I even bought one for my Hellcat. $1300. I had a carbon fiber tube the other day that was ridiculously light and would have weighed so much more if it was steel.

    My guess is that the industry isn't ready to make certain things yet.
  11. Markoni35

    Markoni35 TS Addict Posts: 325   +137

    Carbon fiber used in car industry and aviation is not really "carbon nanotubes". It has nothing to do with electronics or signal processing. It's as related to computer microchips as silicone boob implants are to Ryzen 5.
  12. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,639   +1,233

    I understand that. My point is "Carbon" is going to have wide reaching implications.

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