New Solution For Your Transistor BBQ 191
servantsoldier writes "There's a new solution for the transistor heat problem: Make them out of charcoal... The AP is reporting that Japanese researchers, led by Daisuke Nakamura of Toyota Central R&D Laboratories Inc., have discovered a way to use silicon carbide instead of silicon in the creation of transistor wafers. The Japanese researchers discovered that they can build silicon carbide wafers by using a multiple-step process in which the crystals are grown in several stages. As a result, defects are minimized. Other benefits are decreased weight and a more rugged material. The researchers say that currently only a 3" wafer has been produced and that a marketable product is at least six years away."
Finally... Heat can be put to good use (Score:5, Interesting)
The amount of heat being generated by chips does not seem to be decreasing at all, and this material appears to be produced to be "heat resistant" instead of more efficient.
How long until your PC puts out enough heat that it would be economical to re-use that heat for a hot water tank, or for winter heating?
How long until we need special 240V plugs like electric stoves have for power?
I think that emphasis on more efficient chips is a better venture than heat resistant materials, as the whole heat byproduct of CPU's seems to be sprialling out of control.
Josh
Next step: diamond (Score:2, Interesting)
http://www.eetimes.com/at/hpm/news/OEG20030822S00
What about electrical properties? (Score:5, Interesting)
I would be more interested in band gap voltage, electron/hole mobility etc.
Who needs a chip that can run hot when it cannot run fast?
Maybe for specialized hardened aplications like space, but I don't see these being used for mainstream applications.
Re:Finally... Heat can be put to good use (Score:3, Interesting)
Heat resistance isn't the point -- current IC's don't melt, they get trashed via difusion processes that will still be there in SiC.
The advantage of SiC is substantially enhanced (2x) thermal conductivity vs. Si. This makes it easier to get heat out of the chip, allowing it to run cooler at any given heat production rate.
Re:Sigh, i must be really tired. (Score:5, Interesting)
Silicon Carbide does work -- Cree, Inc. [cree.com] of Durham, NC has been manufacturing electronics (particularly blue LEDs) for years using silicon carbide as the substrate. The technology was developed at NC State University, as I recall.
Re:Charcoal? (Score:5, Interesting)
I've got a quitea bit of experience with SiC abrasives, what with the materials engineering and being a bit of a lapidary.
First off, it's nowhere near diamond in terms of hardness. The Mohs scale is semi-arbitary in assignement, and not even vaugely linear. On proper hardness scale (in this case Vickers), diamond has a hardness of around 90 GPa, compared to about 25 GPa for SiC. That's the reason I've got a box full of diamond abrasives, despite the cost (about 30 times more expensive), they are much faster, and last almost indefinitly. More later on this.
Secondly, SiC needs to be rough. If you don't belive me, try grinding a carrot into shape on a window. The glass is very much harder then the carrot, but is nearly perfectly smooth, and as such, the carrot just sides about. Compare with rubbing the carrot on something like a concrete paving slab, which grinds it much better. The reative hardnesses are wrong here, but show the need for surface roughness.
As an aside, if you think that paper cuts are bad from standard office paper, then try getting one from fine SiC abrasive paper. Stiffer paper, cuts deeper, and the abrasive roughs up one side of the cut, so it takes about four times as long to heal. It's a mistake I've made exactly once.
A processor is not a single pure material - if it was, it wouldn't do anything. They are a complex layered system, with layers of copper and SiO. Trying to grind anything with a processor die will just succed in scraping off all that important stuff. The hardness of SiO is Mohs 7, well below that of anything actually used as an abrasive for metals. (It's the same as ground glass, near enough, sometimes used for abrading wood or plastics).
For comparison silicon has a hardness of 12 GPa Vickers. SiC is only around twice as hard as that.
So, no, you can't really use it as an abrasive. If you really want to be very careful, you might be able to use the edge of the die as a scraper, but you'd probably just remove the important stuff.
That's alla moot point, however. I strongly supect that you'll never see the actuall die, it will be under a metal heat spreader. Because they can cope with higher temperatures [0], there is even less need to take the risk of mishandling breaking the die.
And lest you think that SiC would be less likely to break then silicon, I'm afraid not. Aside from the fact that many broken Athlons are due to the top few layers of SiO and metal breaking, SiC is not that tougher than silicon. As any lapidary will tell you, it's perfectly possible to chip saphire and diamond, if you're not careful.
Still, I can't deny that facts aside, it's a wonderfuly evocative metaphor.
[0] And how much higher! Silicon tops out at 350 C, SiC could operatate at 600 C, where is it glowing red hot! sourced from Nasa [nasa.gov]