Building Complex Circuits With Carbon Nanotubes

Lorien_the_first_one writes "MIT's Technology Review reports that carbon nanotubes are being used to fabricate complex circuits. From the article, 'The first three-dimensional carbon nanotube circuits, made by researchers at Stanford University, could be an important step in making nanotube computers that could be faster and use less power than today's silicon chips. Such a computer is still at least 10 years off, but the Stanford work shows it is possible to make stacked circuits using carbon nanotubes. Stacked circuits cram more processing power in a given area, and also do a better job dissipating waste heat.'"

Comments

Re:So this means 3-D processors, right?

[LordofEntropy]

From the FA:

"A recent IBM study showed that for a given total power consumption, a circuit made from carbon nanotubes is five times faster than a silicon circuit"

And:

"The Stanford group is currently working to make ever more complex integrated circuits. "So far as complexity is concerned, there is fundamentally no barrier" on carbon nanotubes, says Mitra."

So at least in theory not only can the designs be updated as you mentioned, but they should be able to get pretty crazy with said designs.

Re:Heat dissipation

[vlm]

How do stacked circuits do a better job of dissipating heat than a flatter circuit that can dump heat to a heatsink on at least one side?

The article didn't mention any heatsink limitations, or at least firefox didn't find that word. Some weird fractal shaped device with a bunch of sides? Of course the minimum volume design would be a sphere, which has minimum surface area per volume, kind of counterproductive.

My guess is going 3-d allows the heat generation of the whole die to approach the max... Rather than having regions that run hot and regions that run cold, with the limit of the whole device being the hottest little part, you could spread the hot parts around the die, in theory maybe every little portion of the die could dump exactly the same amount of heat, for a given workload anyway...

So in 10 years?

[gmuslera]

Looks like 5

Re:So in 10 years?

[Interoperable]

Very true, 10 years seems very optimistic considering the colossal challenges of reliably growing nano-tubes. The technique presented in the article offers a way to work around defective (conducting) nano-tubes rather than eliminate such defects. The research done here is very interesting, but processors need to be stamped out by the millions; a technique that requires manipulation of tubes that is customized to each circuit based on random yields simply can't be scaled up into full production.

Before nano-tube processors come out, the defect rate would have to be low enough that most processors have zero (or few) defects rather than each requiring careful tuning of each gate to get them functional. I think this is a case where there will be a big gap between the proof-of-principle functional gates in labs and a marketable product. Still, the prospect of three-dimensional nano-tube processors is very exciting even if it's a long way off. The work presented in the article is also very interesting and is certainly a clever technique, even if it may not find commercial application for a long time.

Re:So this means 3-D processors, right?

[vlm]

What is this going to change? I guess it would be easier to update the designs because you don't have the 2-D crosspath issue anymore. And you should also have shorter distances between components. Is there anything else significant?

Without the limitations of 2-D interconnects, you could:

build barrel rollers / barrel shifters in the shape of a barrel...

http://en.wikipedia.org/wiki/Barrel_shifter

build ring oscillators and ring counters in the shape of a ring...

http://en.wikipedia.org/wiki/Ring_oscillator

Currently, using 2-D techniques, you can easily build on-die flat arrays of parallel processors. With 3-D, I guess you could build on-die 3-D arrays of parallel processors. Still out of luck for hypercube (4-D) architecture, although wiring might be somewhat simpler..

Re:Heat dissipation

[Geoffrey.landis]

> How do stacked circuits do a better job of dissipating heat...

They don't, nor does the article claim that they do.

Darn, where's that "-1: did not read as far as the last line of the summary" moderation option when I need it???

Will this make?

[ModernGeek]

Will this make "the Internet is a series of tubes" true?

progress, kind of

[Goldsmith]

These are more or less the same techniques we used in carbon nanotechnology 10 years ago. The difference is that now there are more than 2 or 3 groups capable of mastering all these techniques. It's nice to see everyone hasn't given up on this material and that engineers have taken over now that all the scientists have moved on to graphene. It's still far too expensive to make transistors from carbon nanotubes, but maybe they're right and these labor-intensive techniques used can be automated.

Re:Heat dissipation

[A nonymous Coward]

It's in the last line of the moderators' guidelines ...