Friday, August 30th 2019

Researchers Build a CPU Without Silicon Using Carbon Nanotubes

It is no secret that silicon manufacturing is an expensive and difficult process which requires big investment and a lot of effort to get right. Take Intel's 10 nm for example. It was originally planned to launch in 2015, but because of technical difficulties, it got delayed for 2019. That shows how silicon scaling is getting more difficult than ever, while costs are rising exponentially. Development of newer nodes is expected to cost billions of Dollars more, just for the research alone and that is not even including the costs for the setting up a manufacturing facility. In order to prepare for the moment when the development of ever-decreasing size nodes becomes financially and physically unfeasible, researchers are exploring new technologies that could replace and possibly possess even better electrical properties than silicon. One such material (actually a structure made from it) is Carbon Nanotube or CNT in short.

Researchers from MIT, in collaboration with scientists from Analog Devices, have successfully built a CPU based on RISC-V architecture entirely using CNTs. Called RV16X Nano, this CPU is currently only capable of executing a classic "Hello World" program. CNT is a natural semiconductor, however, when manufactured, it is being made as a metallic nanotube. That is due to the fact that metallic nanotubes are easier to integrate into the manufacturing ecosystem. Its has numerous challenges in production because CNTs tend to position themselves randomly in XYZ axes. Researchers from MIT and Analog Devices solved this problem by making large enough surfaces so that enough random tubes are positioned well.
The CPU is based on the RISC-V architecture, particularly it is designed to handle 32-bit wide instructions in a 16-bit wide memory address design. Being that all stages of the CPU pipeline (Instruction Fetch, Decode, Register Read, Execute and Write Back) are 16-bit in width, the CPU is officially declared as 16-bit. It uses 14,000 logic gates, like AND or NOT gates, to become a fully functional design. Given the careful manipulation of nanotubes, researchers managed to pull off 100% yield, meaning that all of the 14,000 gates worked correctly. Here is the waveform of execution of the Hello World program (while it isn't exactly Crysis, given the position of this technology, it is quite an impressive achievement):
The technology isn't perfect, yet. The chip ran at a very low clock speed of only 10 kHz, which means that your average CPU is an order of magnitude faster than this. With all of the flaws, this demonstration is an important achievement for the technology - a proof of concept. It shows that you are able to manufacture a working example of CPU based on something that doesn't require silicon and possibly is even better than it. We just haven't perfected all of the bits and pieces required to get CNTs at the same level of performance we already have. Sources: Nature Magazine, ArsTechnica
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40 Comments on Researchers Build a CPU Without Silicon Using Carbon Nanotubes

#1
Tomorrow
About time. We've been hearing about CARBON NANOTUBES for what seems like a decade without so much as a working prototype.
I highly suggest you check out Coreteks's latest video where he speculates on the next 30 years of chip manfufacturing including CARBON NANOTUBES:
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#2
64K
I read an article a few years ago on Ars Technica about using carbon nanotubes to replace silicon. It's pretty interesting. The scientists speculated that using carbon nanotubes for transistors could be up to 5 times faster than silicon while using 1/5th the power. That would be an incredible advancement for so many devices if they can work the bugs out.

If carbon nanotubes doesn't work out then some other material will. Silicon is definitely not the future. It's getting more and more expensive as the process node shrinks. One day it may be possible to continue to shrink but not economically feasible to do so.

[IMG alt="computer chip"]https://www.sciencenews.org/wp-content/uploads/2019/08/082719_mt_nanotubes_inline_680_rev.jpg[/IMG]

"A new kind of computer chip (array of chips on the wafer pictured above) contains thousands of transistors made with carbon nanotubes, rather than silicon. Although the current prototypes can’t compete with silicon chips for size or speed yet, carbon nanotube-based computing promises to usher in a new era of even faster, more energy-efficient electronics."

https://www.sciencenews.org/article/chip-carbon-nanotubes-not-silicon-marks-computing-milestone
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#4
Crackong
Carbon Nanotube process is also an expensive and difficult process which requires big investment and a lot of effort to get right.
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#5
BakerMan1971
Raging at my PC and calling it a CNT will be valid finally
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#6
fynxer
Intel's 10nm 4 year delay is not much of an example since the rest of the industry is going in to 5nm and already working on 3nm.

With 10nm they put all eggs in one basket and failed, greed and hubris got in their way by selecting the cheaper way to do 10nm by default.

You could say karma is a b1tch, this one decision gave AMD the future lead in the cpu business and i am so happy Intel screwed over them self's.

A greedy company like Intel should never ever have any kind of monopoly because they will self destruct by prioritising profit over technical advancements.

I am sure someone will develop a new way of doing cpu's without silicon long before Intel.
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#7
windwhirl
windwhirl
Carbon nanotubes can not replace current silicon-based technologies because there is no way to mass-produce them yet. With current technology, you could make at best a few dozens of thousands of carbon nanotube transistors in a relatively short time. A processor would need at least hundreds of millions (for example, the Core i7 980 had 1170 million transistors and 8-core Ryzen processors almost reach the 5 billion mark). And then you would have to make millions of processors.

Besides, and before that, you need to have people in R&D that know all the ins and outs of carbon nanotubes, and we still haven't discovered everything about them. So, I'd say it would take ten years more at least before we see them in everyday technologies.
I said this sometime ago, and while I haven't changed my opinion, hopefully it will take a little less time to see it in actual products.

The next few years sure look quite interesting, though.
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#8
Carminus
BakerMan1971
Raging at my PC and calling it a CNT will be valid finally
I was waiting for it....
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#9
Mephis
fynxer
Intel's 10nm 4 year delay is not much of an example since the rest of the industry is going in to 5nm and already working on 3nm.

With 10nm they put all eggs in one basket and failed, greed and hubris got in their way by selecting the cheaper way to do 10nm by default.

You could say karma is a b1tch, this one decision gave AMD the future lead in the cpu business and i am so happy Intel screwed over them self's.

A greedy company like Intel should never ever have any kind of monopoly because they will self destruct by prioritising profit over technical advancements.

I am sure someone will develop a new way of doing cpu's without silicon long before Intel.
Gotta love how it only took 6 comments for someone to bash Intel on an article having nothing to do with them.
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#10
ratirt
Carbon nanotubes. Yeah been hearing about this a lot lately. It doesn't mean necessarily that the advancement will have to take 30 years to catch-up. This depends on the research and how many companies or probably researchers will be involved. This is a rough estimate and believe it or not, it will be way faster. Starting is basically the worst part after that you take a leap forward. Especially if you have a proof of concept and we have that already.
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#11
rutra80
So it roughly is as fast as ENIAC from 1945, though surely more energy efficient...
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#12
Athlonite
I'm picking Quantum CPUs will be out for the consumer before this ever makes it to market
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#13
kapone32
Athlonite
I'm picking Quantum CPUs will be out for the consumer before this ever makes it to market
Haha probably not you have to hit -1,000,000 Kelvin to get Quantum CPUs to even do what they are supposed to do. We will need an Alexa sized cooler to be able to do that at home and that is many years away.
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#14
Mephis
kapone32
Haha probably not you have to hit -1,000,000 Kelvin to get Quantum CPUs to even do what they are supposed to do. We will need an Alexa sized cooler to be able to do that at home and that is many years away.
Not only that, but quantum computers don't lend themselves well to doing everyday tasks. For certain problems, yes they eventually can be faster than classical computing, but for the consumer, no.
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#15
kapone32
Mephis
Not only that, but quantum computers don't lend themselves well to doing everyday tasks. For certain problems, yes they eventually can be faster than classical computing, but for the consumer, no.
Exactly they are building them to do calculations for complex problems at the molecular level, or solving quantum mechanics equations mostly but the thought of a CPU processor having 4 different states for instructions is crazy.
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#16
Mephis
kapone32
Exactly they are building them to do calculations for complex problems at the molecular level, or solving quantum mechanics equations mostly but the thought of a CPU processor having 4 different states for instructions is crazy.
Yeah. I can grasp how classical computing works, but start reading about quantum computing and my head hurts.
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#17
kapone32
Mephis
Yeah. I can grasp how classical computing works, but start reading about quantum computing and my head hurts.
I know super position, entanglement were so easy for me to understand at a high level but the details are indeed headache inducing.
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#18
ZoneDymo
kapone32
Exactly they are building them to do calculations for complex problems at the molecular level, or solving quantum mechanics equations mostly but the thought of a CPU processor having 4 different states for instructions is crazy.
Who knows, maybe for example games are calculated eventually on an ingame molecular level for realism :P
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#19
notb
Athlonite
I'm picking Quantum CPUs will be out for the consumer before this ever makes it to market
So?
Different computers for different tasks.

CNT is just another candidate for future CPUs like we have today: deterministic, binary. We know silicon's potential is ending. We already have better semiconductors that work (like GaN), but they're more expensive, so won't be used until there's no other way.
Quantum computers will be used for different problems. You won't run Windows on them. Ever.
kapone32
Haha probably not you have to hit -1,000,000 Kelvin to get Quantum CPUs to even do what they are supposed to do. We will need an Alexa sized cooler to be able to do that at home and that is many years away.
Seriously...
https://en.wikipedia.org/wiki/Kelvin
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#20
wiyosaya
IIRC, CNTs are better conductors of heat, too! IMO, this is a step in the right direction.
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#21
Midland Dog
BakerMan1971
Raging at my PC and calling it a CNT will be valid finally
gold
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#22
DeathtoGnomes
The question is whats the smallest size is achieveable that is still practical, will CNT be better or will silicone in the long run? That is assuming smaller is still better. I'm betting that CNT will be more reliable when the process reaches picometers (unless they use angstroms as the unit of measure).
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#23
notb
wiyosaya
IIRC, CNTs are better conductors of heat, too! IMO, this is a step in the right direction.
Not really.
A single CNT can be a fantastic thermal conductor... along it rotational axis ("through" the tube) and basically an insulator in perpendicular direction.
A randomly aligned CNT material is a worse thermal conductor than copper.

Making big chunks of aligned CNTs is at this moment under research. It may never be easy and cheap enough to be used in consumer CPUs or cooling solutions.

Also, keep in mind the best thermal conductivity is true for CNTs that are electric conductors - hence not usable as silicon replacement.
CNTs that end up in CPUs (if it ever happens) will have different physical properties and lower thermal conductivity.
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#24
FinneousPJ
An order of magnitude? My CPU is multiple orders faster.
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#25
notb
FinneousPJ
An order of magnitude? My CPU is multiple orders faster.
Your Ryzen is also many orders faster than other CPUs made today. Computers aren't just the x86 machines we think about most of the time.
If you're around 40 or more, your PC CPU is multiple orders faster than another PC CPU you've likely owned in the past.

Anyway, this is all irrelevant.
Even if these carbon CPUs can only do very simple stuff today, they'll catch up at some point. Maybe in 5, 10 or 50 years - we don't know that. But we know their theoretical limits are far beyond what silicon offers.
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