New Solution For Your Transistor BBQ

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."

Comments

Re:typical bad science journalism

[mikeophile]

The chip itself isn't lighter, but the cooling equipment required can be much smaller, making for much lighter and rugged devices that use those chips.

But yeah, that article was pretty light on details.

Re:how hot?

[struppi]

Here's some more information about this topic:

http://www.grc.nasa.gov/WWW/RT1997/5000/5510neudec k2.htm
http://www.acreo.se/templates/Page____577.aspx

I just asked Google

Re:Finally... Heat can be put to good use

[Anonymous Coward]

Most countries have 240v to begin with.

Re:Finally... Heat can be put to good use

[ozbird]

The amount of heat being generated by chips does not seem to be decreasing at all ...

I disagree. I've just upgraded an Athlon XP 1800+ system to an Athlon64 3500+.
The new box runs around 20 degrees C cooler than the old one at idle and under heavy load; both use the supplied retail AMD heatsinks. I'm not using "Cool 'n Quiet" on the '64; it might take a bit off the idle temperature, but I don't see the point.

Re:Wow

[Anonymous Coward]

I live in Japan and work for a Japanese company. Trust me, stupid business process patents are not unique to the U.S. Our company has attempted (sometimes successfully) to patent some of the most obvious, blatant crap by tagging "online" onto it. AND WE'RE NOT EVEN A TECH COMPANY!!

In the event that we find out that someone else already HAS "invented" this idea, it is usually NTT (Nippon Telephone and Telegraph) which has also registered the hell out of a shit load of trademarks that it doesn't use.

And, over here, there are a lot of people worried that we've really lost our tech edge against China and Taiwan. To a certain extent, I think they're right. China and Taiwan used to be copiers, not innovators. But then again, so was Japan half a century ago. Recently, China and Taiwan have started innovating too. It should have been obvious that they "could" innovate, about 18 years ago when the first fake Nintendo consoles from Taiwan were found. They say over 80% of the circuitry, including the CPU, was original, and not a copy. (Then again, a lot of the fake Apple IIe machines back then were pretty original too, sometimes with features that weren't available on the real thing!)

What does silicon carbide have to do with a BBQ?

[Jason1729]

Silicon carbide is a very hard, brittle material with a very high melting point commonly used to make crucibles and high speed saw blades and drill bits.

Comparing this to charcol is like saying that Carbon Monoxide is the same thing as Oxygen because CO contains oxygen.

Jason

intended for extreme conditions

[Anonymous Coward]

from the article:

Devices built with the rugged material would not require cooling and other protections that add size, weight and cost to traditional silicon electronics in power systems, jet engines, rockets, wireless transmitters and other equipment exposed to harsh environments.

So you see, besides that it is nearly as hard as diamond and can survive the temperatures of re-entry into the Earth's atmosphere, they want use it to replace silicon electronics that are used in more stressful environments. Although I suppose that the over-clockers should rejoice.

All this silly stuff, but

[panurge]

Silicon carbide and diamond both have significant potential use as power semiconductors. Forget CPUs, think I/O. Think smaller power supplies, smaller audio drivers, more rugged automotive systems, and, ultimately, being able to shrink robotics controllers as a next step to producing very small robots. If a robot's motors are running at 80C, you want the power semis to be able to handle that. Furthermore, a lot of possible fuel cell designs run at fairly high temperature and, again, you want the electronics to survive the environment without too much cooling.

There are also huge potential benefits for rad-hard communications satellites, where cooling is a major problem (radiation only.)

The BBC article

[Mixel]

linky

Cooler != less heat produced

[EnglishTim]

Just because your CPU runs cooler does not neccesarily mean it generates less heat. To do a proper test, use the heatsink supplied for use with your Athlon 1800+ and pop it on your Athlon64...

It's possible all you've proved is that coolers are getting better quicker than processors are getting hotter...

Read the post again

[panurge]

80C is a realistic maximum case temperature for DC motors, which I used as an example. If the environment reaches 80C, what do you think the junction temperatures of the transistors will be?

Also, please note that the junction temperatures you quote are maxima. You will not get good life at high temperatures with silicon but, more importantly, the ability to handle pulses and voltage drops as junction temperature rises. I suggest you look at the SOAR curves for a few power devices to see what I mean.

As for the rest of your remarks, it's clear you are not a serious power electronics designer. No-one says the low level stages have to run that hot (though anyone who has listened to a good tube amp would probably argue that you are exaggerating the importance of shot noise). The big benefit of higher junction temperatures is that heatsinks, in particular, can be smaller, especially if the hot air is vented straight out of the casing. This makes the overall size of the equipment smaller.

Also, don't forget that power amplification is not synonymous with hi-fi. There are many applications for power audio devices (PA systems, for instance) that require considerable audio power but only moderate quality, and the applications for compact RF devices are continually expanding. For instance, one possible goal for a high power SiC device would be a replacement for the magnetrons of microwave ovens, possibly even creating a market for small solar or wind powered microwave ovens that would be useful both for backpackers and for 3rd world countries.

Re:Charcoal? Isn`t a bit hard to saw wafer?

[DarkMan]

Nah, you just use a diamond saw. Same as for the silicon wafers. It's conceptually the same thing as a very thin diamond tipped grinding wheel, and it grinds a cut through the material. You can also use a diamond encrusted wire as a saw, like, erm, this one *holds one up*, but they are much slower, and only really good as hand saws, or for chopping thin sheets [0].

It's going to be a little slower, as SiC is about twice as hard as silicon, but that's not going to slow it down that much. Diamond saws are also used to chop up boules of sapphire and ruby, which are of similar hardness to SiC (a little softer), and also diamond (harder), so it's no big techical problem.

Or, a laser. A nice big excimer laser would slice it neater than a diamond saw. With the improved surface texture after cutting, the decrease is polishing coupled with the increase in hardness might make it worth while. Probably not, though.

[0] I use my saw for cutting rocks for lapidary purposes, principly quatrz of various sorts.