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Stretched Silicon Speeds Semiconductors
byrd77 writes: "IBM is touting new 'strained' silicon as being up to 35 percent faster while reducing power requirements. Let's hope this is more than just an exercise in straining credulity..." See also their press release.
It's smart to show that your pipeline isn't drying up when people are getting nervous about "next steps".
Why the dubious attitude towards IBM? IBM's discoveries have led to significant breakthroughs in technology. I especially like their GMR technology, and although they DO make money from licensing it (OH NO!!!!!!), it HAS advanced all aspects of magnetic storage substantially. Their SOI technology is also very promising. And look at this, they continue to innovate.
So why this "LOLOL IBM WANTS MONEY!!!" commentary? They're a corporation, yes, but their inventions have a wonderful impact on computers.
1. It'll never work - thats right, if the Ph.ds at the IBM lab had consulted me and my RPG-playing zit-studded freshmen pals, they would have understood how idiotic they were to pursue this work, and to claim that it was a success.
2. Those greedy bastards - how dare they hold this innovation closely and not share it with openwhatever.org?
3. What does this have to do with linux? Philip Greenspun is cool! Craig Mundie sucks dick! RMS and Linus rule too! Steve Case also sucks dick!
Thank you, this is /. bitch, signing off.
How about SOI (silicon on insulator) or Copper chips? These are both available right now....
This sounds a lot like the speech software
/ te _1.html
you describe:
http://www-4.ibm.com/software/speech/enterprise
-Kevin
I agree that strained silicon is a common source of research - that was the point of my post: exactly what did IBM do that causes this to be a breakthrough.
Also, I was not talking about the material properties of SiGe - but of strained Si on a SiGe lattice which is exactly what this press release was about.
Going through each of the points that I mentioned as downsides of the technology:
1. Thermal conductivity: this is a property of the bulk material. Even if the SiGe material is epitaxially deposited on a bulk Si wafer, there will still be a substantial layer of SiGe between the transistors and the bulk material. In flip-chip BGA technology cooling of a chip is from the backside - through the substrate. The substantially lower thermal conductivity of the graded SiGe material used to created the strained silicon lattice in the channel is fairly large and will act to isolate the transistors from the backside cooling, which will induced localized self-heating near the transistor. The temperature of the transistor will rise due to this effect which will reduce the mobility of the device.
2. Junction leakage: the lower conduction band in strained Si will lead to reduced Vt within the channel. This reduced Vt will contribute to enhanced switching performance, but will increase Ioff - the source/drain current that flows when the device is supposed to be off. If the process is modified to increase this Vt, then the mobility will be reduced.
3. The dielectric constant of SiGe - which forms the subtrate under the source and drain is substantially higher than the dielectric constant of Si. The parasitic junction cap in the source and drain to the substrate will thus be higher - not substantially but noticeably.
I would be interested to know on what basis you disagree with these three points. I have followed this subject with interest through my career as a microprocessor design engineer and consider myself very familiar with the issues involved and so I am very curious about the details of what they did.
Which leads back to my question - how did IBM solve these issues - particularly the first one - and if they didn't, then what makes this a breakthrough?
My first question is that researchers at IBM's Research Lab have been working on this for IBM for literally years. I remember reading papers from IBM on this exact same subject back six or seven years ago. They've been fabricating devices back in strained Si/SiGe interfaces and has been presenting papers documenting the mobility improvement for some time now. So the thing that I find truly puzzling is what is the breakthrough? It's not that I don't think this is great, but I fail to see what they are doing now that they weren't doing before.
So what is strained silicon - essentially it's a way of using the lattice mismatch of silicon and SiGe (silicon germanium) to create tensile strain near the material interfaces. This strain reduces carrier scattering and thus improves mobility for both electrons and holes in the inversion layer of the transistor channel. So, in less engineering speak, the charge carriers in the transistor move around easier and thus faster which improves transistor performance. This mobility improvement can be as high as 70% faster than 'normal' silicon channels.
It's worth mentioning the downsides of this technique - which I notice have been ignored in all the articles that I have read. Thermal conductivity of strained SiGe is substantially lower than 'normal' silicon - like an order of magnitude less. So the devices will be much hotter. This 'self-heating' of the devices results in reduced mobility of the charge carriers due to increased carrier scattering - so essentially the devices are so much hotter than they greatly reduce the effect that was created in the first place. Another issue is the fact that junction leakage is much higher. And another is that the higher dielectic constant and lower band-gap of SiGe result in higher junction capacitances in the transistors.
The technology is interesting, but I don't see how they managed to address the issues that have held back the technology so far. It's a shame that they didn't mention potential issues and how they worked around them in the press release, but I guess we'll have to wait for the technical papers at this year's conferences.
* Not Speaking for Intel Corp. *
IBM is using Silicon On Insulator to make microchips these days. In an SOI process the silicon you actually make the transistors on is very thin, at most a few microns, and beneath that is an insulator, such as SiO2.
If instead you do epitaxial Si deposition on another insulating crystal, perhaps sapphire, with a lattice slightly larger than Si's, you get the benefits of an SOI process *and* this improvement from a strained lattice.
This is a real technical coup on IBM's part.
As for diffusion, well, IBM can use dopants with lower diffusivities should this be a problem for part longevity.
So, you need to build the silicon on top of a substrate, with a similar crystal surface, but a larger lattice parameter(s). Then grow the silicon on top of it by some technique that maintains atomic level consitancy between the layers.
This is difficult to do - your basically talking something along the lines of silicon deposited by some for of epitaxial growth - and for thick layers that's a timeconsuming process. And thus expensive.
One thing that was not mentioned was the cost of this trick - how does it compare with germanium or gallium arsnide? (Ok, projected to compare?).
I think that, baring some lucky find, this is going to be more expensive than the befefits, for general use.
Not only that, but the interdiffusion coefficents of a strained material are, in general, faster than for the an unstrained material, so this will decrease the lifetime of the devices.
Interesting idea, though.
--
... googly moogly!
This must by the first time in months an AC has been moderated up to +5.
Wow. I'm not the only guy who moderates at -1...
-grendel drago
Laws do not persuade just because they threaten. --Seneca
Once again, IBM claims to have invented a new amazing technology. Every time I read something about IBM on Slashdot, it's always something very promising, like new dense storage mediums.
But I'm still waiting to see any product that uses their discoveries. It's so disapointing "yeah, we have something that really rocks. But you can't buy it now".
IBM does a marvellous research work, but maybe their press releases are coming too early, they give us fale hopes.
{{.sig}}
In an age of pushing the envelope where even "compatible" mobo/CPU combos can be unstable because of manufacturing deficits we now add an additional source of strain to the hardware.
I give up, where's my 486?
That would kind of make overclockers shoot themselves in the foot.
Don't be too discouraged. Copper interconnects in IBM's chips didn't take nearly as long as I saw some people predicting.
Probably when they develop a 4-dimensional projector that will allow them to project a solid shadow of a 3-D mask into the inside of a block of silicon, and a teleportation device to get the dopant atoms inside.
Or, when they develop completely self organizing semiconductors that can be quickly grown from a single nucleation point.
:)
I am not sure which is more likely
I didn't even know Joan Rivers was in the microprocessor industry.
Way to go Joan.
Oh, _silicon_!
I must admit I only read the press release link which only refers to '35%' not '70%' - 35% is reasonable from 70% if you assume that delays are evenly shared between gates and nets - of course my experience is that while that's true for most paths the ones that come and bite you are the long nets that are mostly RC
These days even process shrinks don't give use the speedups they used to (edge effects, RC delays and all that) - however everylittle bit helps - 35% faster silicon probably means 10% faster chips overall - what we really need is a new way to do interconnect - lasers? room temp superconductors? quantum comunications ["I put a cat in my box I don't know if it's dead why don't you check to see if there's any food missing at your end?" :-]? esp? etc etc
Exactly. Remember that only three years ago I bought an 8 gig HD. Now I can buy one from IBM that's 75, something that IBM is directly responsible for with their development of new hard drive technologies (that, coincidentally, i remember reading about only one or two years ago).
Check out the picture at this article at Yahoo.
Since this guy beat me to the punch on the submission, here's the link to the CNN story that I included: http://www.cnn.com/2001/TECH/ptech/06/08/ibm.silic on.ap/index.html. Just in case anybody wanted it.
--------------------------------------
If Murphy's Law can go wrong, it will.
I wonder if/when IBM and Toshiba would cooperate and combine technologies - or if the two technologies are mutual exclusive. Obviously not a lot of technical data is out for real comparison but does anyone else know? I only have rudiments of Chip Design from my EE classes so I don't claim to:)
Still with the X Architecture claiming 10% better peformance and 20% less power dicipation combined with the 30% gains IBM claims, there is turning out to be a lot more room before we hit the physical limit of Moore's law.
Cool.
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Real or Windows Media only.
--I assume full responsibility for my actions, except the ones that are someone else's fault.
--I assume full responsibility for my actions, except the ones that are someone else's fault.
faster! better! more enviromently friendly! ...
at a price.
Runnin' On Empty
Over the years, a surprising number of innovations have come from stretching materials.
for example:
Edwin Land's Polaroid sheets were plasic stretched "just so", aligning the molecules
to allow only polarized light to pass. The instant cameras came later.
Gore-Tex is a membrane that allows H20-vapor to pass but blocks H20 drops. It is
made by sretching teflon "just so", inducing holes of the correct diameter.
Spring steel is stretched so that the molecules in the alloy align in a way to give it that property.
"Never bullshit a bullshitter" All That Jazz
Let's hope this is more than just an exercise in straining credulity...
Well, it isn't straining credulity, I read it on Slashdot so it HAS to be true!
Isotopically pure Si could be grown strained just as well as natural silicon. Should be no problem to integrate the two technologies, assuming each was economically feasible on its own.
Curtains for windows?
Just an observation.
In 2003 surly current develpoment tech will be implemented which will not require any silicon tech. most devlopment tech utilise GaAs and other substrates. nano tech is also speeding up the move away from si tech. Intramolecular tech will remove the need altogether.
end of rant
Don't worry! Everything is getting nicely out of control....
I am very glad that IBM makes all these breaktrougs on chip making (and on harddisks by the way) but im starting to wonder if IBM stands alone in the research of silicon properties. Because if it keeps up just a little more like this (a few more good inventions/discoveries) you will have to ask IBM permission to produce chips soon. I mean if IBM has patents on all the things that will makes a porcessor fast, less power consumting, cooler, smaller and in the end also cheaper, there will be no compeeting and IBM will be setting the price. Im not saying that they will be "microsoft mean" in their pricing, but one can expect features like that.
There isn't much like the scent of a fresh harddisk
If my Mom was reading their press release and all the drooling media blather on it, she'd be left with the impression that IBM had just invented something new and spectacular.
They haven't. Strained semiconductor production and use has been in the labs for *ages*. Nortel and every other company making lasers and optoelectronics components for fiber-optics systems have been using much more exotic strain-compensated quaternary (compound) semiconductor materials systems for ages. And it was all originally "discovered" in public research institutions and universisites.
All IBM has done is figured out how to work it into their current production line (which is in fact quite an accomplishment).
Let me know when AMD gets strain compensated SiGe into their CPUs. Then I'll get excited.
Took me a couple of readings to guess which one of those links was the press release, and which one of them was the "news".
...and I'd like to see it happen (if this is real), but for all they show off about low time-to-market, I doubt we'll be seeing these too soon, more's the pity :-(
43rd Law of Computing:
I don't think it is. IBM is a fairly stable company and has been around since before computers. They have no reason to lie, not to mention the fact that they are always doing R&D, and therefore often release news about their developments. If I had money to invest, IBM would be one of my top choices...
I meant no fan, always need a heatsink :)
This was a month ago or so, I'll look for a link though.
http://www.theregister.co.uk/content/3/15121.html There you go, minimal cost, 35C temp drop for a 1Ghz processor, almost no Heat sink needed.
its interesting, but AMD is already incorporating a new type of silicon into their chips. The price increase it supposedly quite small, and the performance gain is similar to IBMs technology... but is said to have incredible heat conductive properties, bringing the athlons to almost no Heatsink levels of temperatures. Since this technology AMD is putting in their chips is an extremely pure form of silicon, it might not be compatitible with IBMs research, but you never know.