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New Type of Fatigue Discovered in Silicon

ScuttleMonkey posted more than 6 years ago | from the beat-on-anything-long-enough dept.

Bug 108

Invisible Pink Unicorn writes "Researchers at the National Institute of Standards and Technology (NIST) have discovered a phenomenon long thought not to exist. They have demonstrated a mechanical fatigue process that eventually leads to cracks and breakdown in bulk silicon crystals. Silicon — the backbone of the semiconductor industry — has long been believed to be immune to fatigue from cyclic stresses because of the nature of its crystal structure and chemical bonds. However, NIST examination of the silicon used in microscopic systems that incorporate tiny gears, vibrating reeds and other mechanical features reveals stress-induced cracks that can lead to failure. This has important implications for the design of new silicon-based micro-electromechanical system (MEMS) devices that have been proposed for a wide variety of uses. The article abstract is available from Applied Physics Letters."

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108 comments

Commodity (0, Redundant)

youthoftoday (975074) | more than 6 years ago | (#21510913)

Surely with silicon products such a commodity these days this isn't so relevant?

(nth post?)

Re:Commodity (4, Insightful)

Valdrax (32670) | more than 6 years ago | (#21510975)

A) No, certain grades of silicon are not cheap. (Price out solar panels some time.)
B) This affects the longevity of systems that were assumed to never wear out and limits the applications that they can be used in.
C) When is disposability an excuse for waste?

Re:Commodity (1)

youthoftoday (975074) | more than 6 years ago | (#21511107)

I'm not defending I'm observing! You can't argue that a capitalist system (such as, well, all of global trade) is geared toward profits and maximising commodification? I'm no economist so I'm not going to express anything more specific than that, but you can't argue that the general trend in electronics has been toward production/consumption over maintainability.

Re:Commodity (1)

ackthpt (218170) | more than 6 years ago | (#21511321)

I'm not defending I'm observing! You can't argue that a capitalist system (such as, well, all of global trade) is geared toward profits and maximising commodification? I'm no economist so I'm not going to express anything more specific than that, but you can't argue that the general trend in electronics has been toward production/consumption over maintainability.

And who is to blame for that? Consumers/Corporate buyers?

You may find the headlong trend towards buying new computers slowing quite a bit. You only really need so much horsepower to edit a document or twiddle numbers in a spreadsheet. Adding memory is quite effective rather than just junking the old box. Microsoft's strategy of building bigger versions of windows, which require bigger versions of PCs is flattening out on the curve, with Vista adoption quite slow.

This all means we're trying to get more life out of our computers. As for other electronics, I only buy when I need to replace or upgrade considerably. We aren't all like the japanese buyers of G3 phones who tossed them every few months for the next eye-catcher.

Re:Commodity (1)

Z34107 (925136) | more than 6 years ago | (#21513819)

And who is to blame for that? Consumers/Corporate buyers?

You may find the headlong trend towards buying new computers slowing quite a bit. You only really need so much horsepower to edit a document or twiddle numbers in a spreadsheet

You see, the system works, and it's called "capitalism." Demand for the next widget is slowing because existing widgets work just fine. Supply adjusts, prices stabalize, yadda yadda yadda.

Point is, in a capitalist system, you can't waste something valuable for long - somebody's going to go broke.

Re:Commodity (1, Interesting)

Anonymous Coward | more than 6 years ago | (#21511679)

My first thought was circuit boards in avionics. Surely all those cycles -- nevermind exposure to extreme cold -- are going to put mechanical stresses on boards, which is kinda scary when you consider the level of computer-control in modern airplanes.

Re:Commodity (1)

Falstius (963333) | more than 6 years ago | (#21512359)

Everyone knew these devices wear out, they just didn't know what the cause was. It may be interesting, but not earth shattering.

Re:Commodity (1)

billcopc (196330) | more than 6 years ago | (#21512881)

Can't silicon be recycled ? Consumerism is driven by cheap, short-lived junk that's promptly replaced by more cheap junk. If we can't make these built-to-break gadgets recyclable, we're headed for a brick wall.

Re:Commodity (1)

PhysicsPhil (880677) | more than 6 years ago | (#21513099)

While silicon wafers in principle could be recycled, silicon computer chips can't be. In a typical fabrication process, silicon is coated and exposed to a variety of other contaminants that can't be easily removed. Dopants like arsenic and phosphorous, dielectric coatings like silicon and hafnium oxides, plus a variety of metals for connections would all have to be removed from the chip before silicon could be thrown back into the melt. It's just not worth it for such a small amount of silicon.

Re:Commodity (1)

InvalidError (771317) | more than 6 years ago | (#21515045)

Si being one of the most abundant elements on the planet weights for a lot on the not-worth-it side... but the other rarer elements deposited on the chips could be a different story. Much of these could be recovered my melting thousands of ICs into a single ingot and passing it through an induction oven a few times to separate elements by sedimentation. Since most of the valuable elements used in Si-based ICs are heavier than Si, a fair amount of them would settle near the bottom.

In the days of pre-flip-chip ICs, scavengers were taking apart ICs to recover the gold bonding wires and gold-plated components because there was more gold per kg in electronics than raw ore. Depending on how prices for the other rare elements go, the above recycling process could become economically viable.

Explains the lack of quality. (1)

sethstorm (512897) | more than 6 years ago | (#21511331)

You can't argue that a capitalist system (such as, well, all of global trade) is geared toward profits and maximising commodification?
Shame that quality gets killed in the process, something regulation gladly would keep alive and at a sane price.

Re:Explains the lack of quality. (1)

The_Wilschon (782534) | more than 6 years ago | (#21512097)

Enjoy your Soviet made goods, then. That's some really high quality stuff, it is.

Yes, this is a bit of a strawman, because there's regulation and then there's regulation. But still, I disagree that regulation is the solution we should look to. Frankly, I'm not convinced that the quality of silicon goods is actually that low...

Re:Explains the lack of quality. (0)

Anonymous Coward | more than 6 years ago | (#21512831)

Shame that quality gets killed in the process, something regulation gladly would keep alive and at a sane price.

In Soviet Russia, regulation keeps quality alive and at a sane price.

No, seriously.

Re:Commodity (1)

zhirole nift (771781) | more than 6 years ago | (#21514097)

The only thing I know of that can't be cracked is the thinking of those who believe that some things will never wear out.

Related title (0)

Anonymous Coward | more than 6 years ago | (#21510923)

"New type of fatigue discovered in Silicon Valley"

Re:Related title (3, Funny)

ackthpt (218170) | more than 6 years ago | (#21511241)

"New type of fatigue discovered in Silicon Valley"

Got news for you, it's everywhere. I've got stress fatigue from converting SQL scripts.

Is it just me? (4, Funny)

zappepcs (820751) | more than 6 years ago | (#21510929)

or did anyone else see 'silicon fatigue' and immediately think of something more mammalian in nature?

Re:Is it just me? (0)

Anonymous Coward | more than 6 years ago | (#21510961)

Mammarian.

Re:Is it just me? (-1, Troll)

Anonymous Coward | more than 6 years ago | (#21511019)

Well, i wasn't thinking the exact same thing as you, but when I read the headline, I started thinking about my cock being fatigued after titty-fucking my girlfriend's A cups... and then thinking, damn she could use some implants!!! Anyone who's every tried busting a nut on practically non-existant breasts can relate.

Re:Is it just me? (1, Funny)

Anonymous Coward | more than 6 years ago | (#21511287)

This being slashdot, rest assured that most readers have busted a nut or two on non-existant female anatomical parts of all shapes and sizes.

Re:Is it just me? (2, Funny)

davidsyes (765062) | more than 6 years ago | (#21511041)

I was thinking "New Type of Fatigue Discovered in Silicon VALLEY".

But, now that you're thinking (alluding to breasts/mothers' milk; or rampantly-chewing boys or men on females) "siliCONE", why not think these?:

"New Type of Fatigue in Silicon ALLEY, or"

"New Type of Fatigue (CastroEderItis) RE-Discovered in Castro District"?

"New Type of Parking Discovered in Rear" (More Parking in Rear)...

Such a lovely day...for gags... ummm chokes... umm JOKES...

Re:Is it just me? (1)

davidsyes (765062) | more than 6 years ago | (#21511487)

""New Type of Fatigue (CastroEderItis) RE-Discovered in Castro District"?"

Meant:

"New Type of Fatigue (CastroEndTenderItis) RE-Discovered in Castro District"?

Re:Is it just me? (0)

Anonymous Coward | more than 6 years ago | (#21512141)

And yet it still wasn't funny...

Re:Is it just me? (1)

YU5333021 (1093141) | more than 6 years ago | (#21513175)

I was in Belgrade, Serbia (long forsaken motherland) this summer and was quite impressed (but only briefly) that there was a downtown district called the Silicone Valley! The locals even proudly pronounced it in English: 'Da Silikon Voli!'. I thought GREAT, finally there are some BIG signs of upward turns in economy that has been ravaged in the last 15 war torn years. But Serbs being Serbs...

Yes, there were some HUGHE silicone installations in the district, but it had absolutely nothing to do with tech, although the hourly fees were very comparable to the ones charged by the best of north american silicone researchers.

I'm surprised this isn't in Belgrade's tourist brochures as it should be. Secondly, I propose some kind of a talent exchange between the two valleys: It would be a win-win. Are you a libertarian tech wiz who hates the invasive governments? Come to Serbia where a gun is stomped into your passport as you enter, and where free market is so free you can LITERALLY exterminate your competition without any nanny state nags.

Re:Is it just me? (1)

loconet (415875) | more than 6 years ago | (#21513519)

That is exactly what I thought as well. I thought they had found a new type of work fatigue in workers at Silicon Valley which eventually forced them into doing crack.

Re:Is it just me? (4, Funny)

snowraver1 (1052510) | more than 6 years ago | (#21511043)

I think it's just you. I think that I can speak for most of us here when I say that the word "silicon" is mentally associated with "sexy" things. Things like my xbox 360, CPLDs, diodes, LEDs... I should stop there... I'm turning myself on... Oh baby... TTL chips, CMOS... Good 'ol CMOS never say no when you call her late at night.

NOT LEDs!!! (4, Informative)

mangu (126918) | more than 6 years ago | (#21511255)

LEDs are not made of silicon. They are either gallium arsenide or boron nitride, depending on the color.

Clearly... (0)

Anonymous Coward | more than 6 years ago | (#21511455)

You've never fed a silicon diode enough power.

Mind you, the light doesn't last for very long...

Re:NOT LEDs!!! (1)

davidsyes (765062) | more than 6 years ago | (#21511565)

And, what colors would we get if we (could) make:

Gallium Nitride and Boron Arsenide?

Gallant, galloping nitrogenous, bored asses color spectrum?

Re:NOT LEDs!!! (1)

StickyWidget (741415) | more than 6 years ago | (#21511671)

Silicon carbide is used to make blue LEDs. It's not "Informative" if it's wrong.

~Sticky
/LEDS!!!

Re:NOT LEDs!!! (1)

mangu (126918) | more than 6 years ago | (#21512045)

Silicon carbide is used to make blue LEDs


BZZT, wrong! Silicon carbide WAS used to make the first blue LEDs, but no one has developed a good technique to make silicon carbide crystals, so they switched to boron nitride.

Re:NOT LEDs!!! (1)

ChrisMaple (607946) | more than 6 years ago | (#21512815)

The reason blue LEDs have switched technology is that the new stuff is much more efficient. Cree still makes SiC crystals, even for jewelry.

Re:NOT LEDs!!! (1)

ChrisMaple (607946) | more than 6 years ago | (#21513389)

IIRC, early in the history of blue LEDs, Sony made a silicon-insulator (PIN?) blue LED for medical devices. Silicon is not practical for modern LEDs, but it can be done.

Re:NOT LEDs!!! (2, Informative)

JollyRogerX (749524) | more than 6 years ago | (#21515115)

Wrong. The first LED was made of Silicon Carbide back in the early 1900's. An LED made out of straight silicon would produce infrared light. The reason they don't make infrared LEDs out of silicon today is that they are not as efficient (i.e. they produce too much heat). You can show this is true with Schroedinger wave equations.

Re:Is it just me? (1)

wattrlz (1162603) | more than 6 years ago | (#21511177)

Hopefully it's just you. How exactly does a gel exhibit fatigue? My first reaction was, "Oh noes! My RAM!"

My first thought was of poor Marvin (2, Funny)

spun (1352) | more than 6 years ago | (#21511299)

Now we finally know what was causing the pain in all the diodes down his left side.

Re:Is it just me? (0)

Anonymous Coward | more than 6 years ago | (#21514045)

"or did anyone else see 'silicon fatigue' and immediately think of something more mammarian in nature?"

Fixed it for you. :D

Re:Is it just me? (2, Interesting)

Auraiken (862386) | more than 6 years ago | (#21515847)

I was actually starting to think that maybe "tiny gears" and "vibrating reeds" might be defective by design. Maybe the forms themselves cannot take the stresses very well and lead to fatigue. Is there any research for finding stresses in single forms? like break/crack points between edges and whatnot depending on how they are shaped and how much force is put on them relative to the rest of the structure? or is it 4:30am and i should've went to bed hours ago?

especially if you smoke it (2, Funny)

User 956 (568564) | more than 6 years ago | (#21510949)

However, NIST examination of the silicon used in microscopic systems that incorporate tiny gears, vibrating reeds and other mechanical features reveals stress-induced cracks that can lead to failure.

I can agree with this. In my personal experience, crack inevitably leads to failure.

DLP TV/Projectors, the first consumer victim? (4, Interesting)

Radon360 (951529) | more than 6 years ago | (#21511001)

Are TI's DLP mirror arrays subject to this? Don't know for sure if DLP is presently the largest MEMS rollout (if it is considered a MEMS) to the consumer market right now, but I wonder if anyone has reported mirror failures after a number of longer operating hours?

Just curious.

Re:DLP TV/Projectors, the first consumer victim? (1)

LiquidCoooled (634315) | more than 6 years ago | (#21511059)

I don't think so, they whacked their sample with a hammer until it cracked.

On the other hand, using half the pressure but cycling the test hundreds of thousands of times revealed a gradually increasing pattern of surface damage at the indentation site--clear indication of mechanical fatigue.

The tiny mirrors on the DLP are just going to flex in a magnetic field.
I can grab a piece of wood and wobble it for hours (like Rolf Harris!) without a crack appearing but I can also pound it with a hammer and do a Jack Nicholson impression with the hole.

Re:DLP TV/Projectors, the first consumer victim? (1)

davidsyes (765062) | more than 6 years ago | (#21511635)

Are you trying to excite snowraver1 (1052510)? Did you read his/her:

"Things like my xbox 360, CPLDs, diodes, LEDs... I should stop there... I'm turning myself on... Oh baby... TTL chips, CMOS... Good 'ol CMOS never say no when you call her late at night."?

Re:DLP TV/Projectors, the first consumer victim? (1)

StaticEngine (135635) | more than 6 years ago | (#21511105)

I have a 720p DLP set, so I'd like to know the answer here as well. However, I do recall during my due dilligence research reading that the mirrors only flex through about 10 degrees of travel, and were tested through hundreds of thousands of flexes with no perceptable damage.

Re:DLP TV/Projectors, the first consumer victim? (1)

wattrlz (1162603) | more than 6 years ago | (#21511239)

At 30fps, "hundreds of thousands of flexes" might get you through the LOTR trilogy, if you're really lucky.

Re:DLP TV/Projectors, the first consumer victim? (4, Informative)

StickyWidget (741415) | more than 6 years ago | (#21511305)

The answer is no, but it could be subject to other types of mechanical stress. The difference is that the experiment was done to gauge damage from differing direct pressure, DLP use something called a micro mechanical torsion spring. The experiment doesn't quite scale to the spring. However, the way the torsion spring works is that it allows twisting, kind of of like the old "bird in the cage" [bizarrelabs.com] persistence of vision trick. It's designed to accept a degree of stress from the pressure of twisting. Conceivably, if the crystal layers were aligned in a way that put differing stresses on different layers, it could be an issue. Kind of like if you do the bird trick too long you start seeing small bits of thread pop off from the main string.

However, the kind of tolerance is *probably* already present in the DLP chips. The forces that the spring is subjected to were carefully calculated, and the technology has been in use since the 60s. You could probably take a look at the older types of DLPs and compile evidence that a large amount of cycles won't harm it.

Caveat: I am not a micro-mechanical device engineer, but I follow developments. I figure micro-mechanical devices will need control systems of some sort someday.

~Sticky
/It's all about temperature, pressure, and friction.

Re:DLP TV/Projectors, the first consumer victim? (2, Informative)

nullspace (11532) | more than 6 years ago | (#21511729)

Actually, Analog Devices probably has a larger MEMS rollout and probably for a longer time. MEMS is incorporated into airbag systems [analog.com] (about 200 million units and the largest market share at around 60%), IBM's Active Protection System for Thinkpads [nanotechwire.com] and of course Nintendo's Wii controller [analog.com]. I would assume that this fatigue would be something worthy of further examination. Disclaimer: I work for Analog Devices, but not as a product designer.

Re:DLP TV/Projectors, the first consumer victim? (0, Redundant)

mollymoo (202721) | more than 6 years ago | (#21511927)

The fairly recent appearance of motion sensors in everything from mobile phones to games consoles is due to MEMS technology. If you're a geek, it's quite likely you've got a MEMS device already and it's likely made by Analog Devices [analog.com].

Re:DLP TV/Projectors, the first consumer victim? (1)

mollymoo (202721) | more than 6 years ago | (#21512079)

That'll teach me to hit refresh before posting, nullspace got there first with basically the same information.

Airbag sensors are the highest volume MEMS... (2, Informative)

StandardCell (589682) | more than 6 years ago | (#21513143)

...and as for DLP, it's a valid question especially given that they oscillate rapidly thousands of times a second to simulate brightness levels (they're pulse width modulated to full reflect or full absorb mirror positions). However, the NIST abstract says that their test is done with a spherical indenter presumably imparting impulsive loads of some magnitude. I don't know how big the sphere is or what material it's made of since I don't have the full article, but I'll assume it's some microscale silicon ball; hopefully they didn't do something like ceramic shattering glass easily with little force. DLP stresses would normally be torsional stress along the micromirror hinge of a magnitude dependent on the deceleration at the limit of the DLP motion and the mass of the mirror. Now, if TI was clever and didn't modulate the mirror past the elastic limit of the material, they might be able to largely overcome this problem. Cantilever-style micromirrors might not fare as well because the material is always being deformed, though I again assume they do a stress-strain plot to ensure they don't go past the elasticity limit. On that note and to come full circle, one would assume that sensors do not exceed their ductile elasticity limit except in critical situations, such as high shock as is found in an abrupt movement of an accident. Then again, they're typically single-use.

Digital Micrometer Device - torsion hinge life exp (1)

Steve Hamlin (29353) | more than 6 years ago | (#21514465)


The torsion hinges that support the micromirror on Digital Micromirror Device [wikipedia.org] (DMDs) are said to be good for at least a trillion (10^12) operations. Source: Wikipedia, which has no footnote link to an authoritative source :(

Wiki also says [wikipedia.org] that, at least for a DLP projector, the "DMD chip can be easily repaired or replaced".

What does a trillion operations means to you or me? Is that MTBF, or some other metric? No idea. Back-of-the-napkin (assumption: 1 operation/frame):

- 10^12 ops divided by (30 ops/sec) = 33,333,333,333 secs = 9,259,259 hours = 1,057 years.

If it's 100 operations per mirror per frame instead of 1, then that's still 10 continuous years of operation.

There is probably a nice function that can tell you how quickly the actual failure rate per mirror translates into visible degradation of picture quality over the whole screen over time. Does anyone know if the useful life of the screen would be longer or shorter than the MTBF of an individual mirror? Things to consider: MTBF/mirror, deviation of MTBF/mirror, # of mirrors/pixel (wobulation), # or mirrors, and statistics that I don't know.

But in any event, mirror life seems reasonable. At a minimum, it doesn't seem to be enough of a worry to be publicized widely (vs. everyone knowing there were concerns about the life of early plasmas)

Small gears vs. Large gears? (3, Informative)

StickyWidget (741415) | more than 6 years ago | (#21511055)

Duh.

Study was conducted on the micro-mechanical objects modeled after mechanical objects in the macro- world. So, in essense, small gears will wear down and break just like big gears do. This isn't really a discovery, all large mechanical devices are subjected to a rigorous set of conditions that they will encounter. Just because a group of scientists never subjected the micro-versions to the macro-equivalent test doesn't mean this is new type of stress, it means that nobody though to check it.

And before anybody posts anything about flash memory or processors, this doesn't apply. Memory and processors are "solid state electronics", not "Micro mechanical devices", and are not vulnerable to the same type of stresses (i.e. those caused by friction, shear, or centrifugal forces).

~Sticky
/Duh

Re:Small gears vs. Large gears? (1)

wattrlz (1162603) | more than 6 years ago | (#21511143)

Actually, as I read it, TFA seemed to say that big gears, made of silicon, don't wear down while small ones do contrary to accepted belief, thus making it news.

Re:Small gears vs. Large gears? (4, Informative)

caerwyn (38056) | more than 6 years ago | (#21511167)

You didn't RTFA, did you?

The findings are relevant to silicon precisely because the macro-level tests have *not* shown fatigue cracks. Now, the article suggests that this may be a weakness in the macro-level testing methodology, but it doesn't change the fact that silicon was considered "special" because of it's structure, and now it appears not to be.

So, uh, you've actually got this completely backward. No one thinks it's a new type of stress, it merely wasn't expected that silicon would be susceptible to it.

Re:Small gears vs. Large gears? (0)

Anonymous Coward | more than 6 years ago | (#21511513)

I didn't rtfa but I find it hard to believe somebody has been making gears out of macro silicon wafers cut into gear shapes. What a crappy gear material.

Re:Small gears vs. Large gears? (1)

StickyWidget (741415) | more than 6 years ago | (#21511551)

This example was brought up in a previous comment [slashdot.org], I'm expanding on it.

Assume the resistance of steel to pressure is X. So, I decide to put a weight that exerts a pressure of X/2 and leave it there. NOTHING HAPPENS, ever. So I conclude that due to the structure of the steel, it is immune to pressure effects. OOPS, wrong.

Then, I decided to beat it with a hammer with an impact pressure measured at X/2. Nothing happens, for a long time, likely a very long time. However, eventually there will appear small deformations in the steel that slowly over long periods of repetitive stress turn into massive fissures and eventually cause the steel to buckle.

This type of testing is conducted all the time in mechanical design for macro-sized components. Once again, it is NOT a new type of stress (or fatigue), it is simply that they never subjected it to a repetitive type of pressure scenario. Temperature, pressure, and friction, until you get to the atomic level, they exist and will forever be factors in design.

I'm sorry you had a quibble with the word "NEW", it was meant to signify that the discovery of the stress was new. In my book, it wouldn't merit an "Informative".

~Sticky
/I Did RTFA.

Re:Small gears vs. Large gears? (1)

StickyWidget (741415) | more than 6 years ago | (#21511613)

Crap.

Me:Temperature, pressure, and friction, until you get to the atomic level, they exist and will forever be factors in design.

I deserve a dunce cap for that one.

Edit:Temperature, pressure, and friction, even when you get to the atomic level, they exist and will forever be factors in design.

~Sticky
/Dunce

Re:Small gears vs. Large gears? (0)

Anonymous Coward | more than 6 years ago | (#21511815)

Next wuestion:
Did you understand the FA?
Your example is completely WRONG.

"and it has long been believed to be immune to fatigue from cyclic stresses because of the nature of its crystal structure and chemical bonds. And indeed, conventional tests have validated this."

Let me know if I need to use smaller words.

Re:Small gears vs. Large gears? (0)

Anonymous Coward | more than 6 years ago | (#21515765)

And before anybody posts anything about flash memory or processors, this doesn't apply. Memory and processors are "solid state electronics", not "Micro mechanical devices", and are not vulnerable to the same type of stresses (i.e. those caused by friction, shear, or centrifugal forces).

But surely there are other mechanical forces, such as electric force. I mean, dielectric in capacitors connected to varying electric field is subjected to certain mechanical stress as well (a while ago there was an article here on /. about spying on computers by listening to ultrasound emanating from capacitors on board) and certainly there must be some mechanical tension involved with varying voltages on silicon dioxide (MOS gate) capacitors in chips. In fact, piezoelectric characteristics of silicon dioxide (aka "quartz", in its crystalline form) are well documented, so there ought to be a lot of very high pitch vibrations in your processor. In some special cases it is perhaps possible to have constructive interference pattern on some part of the chip, that could shorten its life, or do as much as cause increased noise in some transistors (MOS capacitor acting as piezoelectric vibrations to voltage transducer) leading to intermittent faults. Now imagine what could mechanical resonance do from even a weak on-chip vibration source!

Perhaps mechanical analysis should be part of silicon design as well.
Perhaps specs should include "forbidden" frequencies for main clock or forbidden products frequencies, together with "absolute maximum" durations.
Or, perhaps each chip should have active damping circuitry on die to detect and spoil resonances.

oh well... a more expensive alternative (2, Funny)

moondo (177508) | more than 6 years ago | (#21511101)

Diamonds are forever~

Re:oh well... a more expensive alternative (2, Interesting)

SEE (7681) | more than 6 years ago | (#21511385)

Diamond is metastable. Graphite is forever.

Re:oh well... a more expensive alternative (1)

geekoid (135745) | more than 6 years ago | (#21511571)

Then how do you explain my pencil needing sharpening?

Re:oh well... a more expensive alternative (2, Informative)

pimpimpim (811140) | more than 6 years ago | (#21513429)

When you write with a pencil you move graphite layers around, from the pencil to the paper. They stay graphite layers, however. The point is in the layers, the layer-layer bonding is weak pi-bonding, which makes it easy to detach the layers from each other by shearing them (e.g. writing).

The point why diamond stays like it is, is that even though it's thermodynamically unstable, it is kinetically stable. In contrast to graphite, it is very hard in diamond to break all bonds between all atoms in the lattice. The chance of this happening is also so small because you would need to break various bonds at the same time, and statistics goes down. In the case that this would happen, however, diamond would be most likely turn into the lower-energy graphite shape.

Another point of view from which diamonds are hardly "forever" is the resale value. A diamond, just like most champagne, isn't really worth much, the worth of a diamond drops tenfold the moment you've put your signature on the receipt. The only reason it is expensive is because they are marketed like that. There are some excellent articles about the marketing around diamonds on the internets.

Re:oh well... a more expensive alternative (0)

Anonymous Coward | more than 6 years ago | (#21511445)

I thought it was now "Diamonds: Take her Breath Away."
Or as, if I recall correctly, Ron White's Interpretation,

"Diamonds.
That'll Shut Her Up."

Re:oh well... a more expensive alternative (2, Funny)

mcpkaaos (449561) | more than 6 years ago | (#21513105)

Well, you know what they say:

A woman without diamonds is a parsnip.

Hah - so much for silicon-based overlords (1, Insightful)

trolltalk.com (1108067) | more than 6 years ago | (#21511127)

Our silicon-bsed overlords can bite my carbon-based ass! Oh wait - they're too fatigued, and crack up under even microscopic stress.

Seriously, this may have implications for the non-existence of silicon-based life. After all, silicon-based "dna" might be more liable to failure.

The fatigue scale is all wrong for today's MEMS (3, Informative)

compumike (454538) | more than 6 years ago | (#21511133)

They're talking about displacements of hundreds of micrometers... it's not clear that any silicon actually displaces that much under any sort of normal operation. Even in common MEMS parts like accelerometers (like those controlling your car airbag or Wiimote), the displacements are tiny -- typically on the order of one micrometer -- although they do happen hundreds of thousands of times per second.

Ever heard of plastic versus elastic deformation? Elastic is when it's small enough to come back to it's original state (no permanent effect). Plastic is when the material is permanently reorganized. They're at a huge displacement scale, so it's not clear how this applies to modern MEMS systems which are moving two orders of magnitude less.
--
if(coder && wantToLearn(electronics)) click(here); [nerdkits.com]

But it makes an upper bound (2, Informative)

EmbeddedJanitor (597831) | more than 6 years ago | (#21511481)

Yes, current MEMS operate at a scale where the effect likely has no impact (probably by a few orders of magnitude). However, previously this effect was thought to not exist and thus was not a factor in future MEMS design. That really only limited MEMS devices to size constraints where there is enough mass etc to provide a measurable effect.

Now that a stress issue has been found that places a limit on how the materials can be used and how much MEMS devices can be shrunk etc.

Re:The fatigue scale is all wrong for today's MEMS (3, Informative)

secPM_MS (1081961) | more than 6 years ago | (#21512433)

There are scale issue here. Even in metals with significant fatigue issues, such as Aluminum, if the structure is thin enough, the image forces on a dislocation suck it to the nearest free surface and you avoid the growth of dislocation tangles that result in fatigue failure. If I remember properly, the relevant thickness for Al was on the order of 100 nm. Note that I am working from memory from grad school ~ 25 years ago, when I did my Ph.D in fracture mechanics.

TI has been working with the mirror systems for a long time now, I suspect on the order of 20 years. They should have real reliability info to work from.

Well, all I can say is... (1)

sherpajohn (113531) | more than 6 years ago | (#21511151)

Our tired silicon overlords are welcome to crash on my couch for a while, 'til they feel a bit less fatigued.

The fact that sillicon can fatigue.... (0, Offtopic)

Therapist of Slashdo (1195429) | more than 6 years ago | (#21511231)

Doesn't actually bear any relevance. If you'd have read the article, or at least the appropriate information [google.com] you would know the real story.

Don't mind me, just trying to help out.

Re:The fact that sillicon can fatigue.... (0)

Anonymous Coward | more than 6 years ago | (#21511431)

WARNING: parent is Goatse link. Now I need some mind bleach.

The journal racket (-1, Offtopic)

Biff Stu (654099) | more than 6 years ago | (#21511237)

If you're a US citizen, you paid for this research. If you want to read the article, you need to pay the copyright holder.

If you're a scientist, it's even worse. You might also be asked to referee the article before it's published, for no compensation and on your own time. If you want to see the final product, you still have to pay the copyright holder.

Obligatory Permutation.... (0, Troll)

graviplana (1160181) | more than 6 years ago | (#21511353)

In SOVIET Silicon, fatigue cracks YOU!

Re:Obligatory Permutation.... (0)

Anonymous Coward | more than 6 years ago | (#21512611)

-1 Troll? That comment was +5 Funny. Someone call the Metamods.

Silicon Fatigue (1)

Dvinn (927610) | more than 6 years ago | (#21511357)

So they are now reporting on the back strain of supermodels? That was my first thought reading the headline...

I'm tired (1, Interesting)

Anonymous Coward | more than 6 years ago | (#21511397)

I wonder where they would get the idea that silicon wouldn't fatigue? Silicon exhibits both electrostriction and magnetostriction, and hence the lattice undergoes strains with changes in electric or magnetic field (as appropriate). Ideally these chips either have no dislocations or maybe just a single screw dislocation. Or rather, the substrate would be that way. But all of the gates and switches and what not will have interfacial dislocations. It would be unusual if dislocation multiplication couldn't take place under micro-plastic flow near these interfaces.

newsflash? (0, Redundant)

Some_Llama (763766) | more than 6 years ago | (#21511505)

I have always told my users (I work IT) that eventually EVERYTHING dies/fails.. thus the need for backups and such.. i've even seen a few processors give up the ghost in my home systems.. why would this be a shock to anyone?

Was there a widely held belief that all computer internals die EXCEPT for CPUs? If so this is the first i have heard of it...

Re:newsflash? (0)

Anonymous Coward | more than 6 years ago | (#21513061)

Newsflash: The article isn't talking about CPUs, computer internals, or even electronic components.

Haven't we known this for a while? (1)

TooTechy (191509) | more than 6 years ago | (#21511593)

This has always been the explanation for why our digital watches run faster every year. Only a second or two, but faster.

Re:Haven't we known this for a while? (1)

mollymoo (202721) | more than 6 years ago | (#21512595)

Surely that's down to the quartz, not the silicon. This research is specific to silicon on small scales.

Re:Haven't we known this for a while? (1)

TooTechy (191509) | more than 6 years ago | (#21514251)

Yep. The quartz is but another form of silicon, in this case SiO2. Whether it from the same cause, I don't know.

Re:Haven't we known this for a while? (1)

imsabbel (611519) | more than 6 years ago | (#21514813)

Well, saying that quarz is just another form of silicon is like saying water is just another form of breathable air...

thermodynamics (1)

gyrocyclist (1122255) | more than 6 years ago | (#21511649)

>has long been believed to be immune to fatigue from cyclic stresses because of the nature of its crystal structure and chemical bonds Um, did someone forget about the laws of thermodynamics?

explosions... (1)

mseidl (828824) | more than 6 years ago | (#21512059)

I want to see silicon nano cars failing and blowing up as they crash into another nano cars.

But, seriously... I want to see more pictures and video. You never see that with these "cool" really tiny things.

Oh noes! (2, Funny)

mgabrys_sf (951552) | more than 6 years ago | (#21512295)

I'll be concerned when they start putting "gears" in my Intel chips. The new Intel Geartron processor - now with gears! Um - no.

I call shenns on this one... (0, Offtopic)

DrStoooopid (1116519) | more than 6 years ago | (#21512551)

...did they ever stop to think that maybe violent types are drawn to these games, and this is their outlet?

Maybe now (1)

iminplaya (723125) | more than 6 years ago | (#21513197)

Some people might realize why I'm a bit leery of carbon fiber. We don't understand their properties as well as we think we do. Back to vacuum tubes for me. Then we really can say the internet is a series of tubes.

Extremadura and Non-Extremadura (1)

gustep12 (1161613) | more than 6 years ago | (#21514473)

Did anyone else notice that the abstract quotes a scientist from a University in Spain called - Extremadura? How fitting for a fatigue testing expert. Is this coincidence? "University of Extremadura finds silicon is not extremely durable after all"

Not "New Type"... (4, Informative)

florescent_beige (608235) | more than 6 years ago | (#21515207)

It's old fashioned fatigue, and it isn't new. This [cwru.edu] paper quotes (2nd para) 1992 work that demonstrated fatigue in micron-sized silicon specimens.

Silicon is a typical low ductility material that does not tolerate cracks very well because there is very little plastic deformation at the crack tip (the process zone). Fracture mechanics is based on an energy balance, when the amount of energy absorbed by the creation of the fracture surfaces (the surface energy) plus the amount of energy required to do that plastic work in the pz is equal to the amount of strain energy in the structure that's released when the crack gets bigger (the strain energy release rate), the crack becomes unstable and the part goes bang.

The strain energy release rate varies with the load and crack size, for a given crack size at loads lower than the critical load, pre-existing cracks (there are always cracks even if they are microscopic) open a bit and the pz deforms. When the load is released, the pz doesn't go back to it's original configuration. Repeating the apply-load remove-load cycle progressively grows the pz which causes the crack to get bigger in some complicated ways. But think of it this way, the crack tip is theoretically infinitely sharp (the limit is the inter-atomic distance of the material). This discontinuity causes infinite theoretical stress which causes the atomic bonds to break at the tip. Process zones have been the subject of countless PhD theses.

In a low ductility material the energy absorbed by the pz is small compared to the energy absorbed by the surfaces created when the crack grows. Remember the pz is responsible for fatigue growth, the pz plus the surface energy is responsible for unstable crack propagation. So a small pz means you have to load the material close to the crack instability load to get fatigue growth. With a small enough pz it's impossible to load the material accurately enough to grow the crack without breaking the part. So THATS what they mean by silicon being immune to fatigue.

It seems like the reason this is not the case in microscopic silicon specimens is another PhD topic, the explanation is complicated. Oxidation caused by humidity in the air is a factor, as well as loading in the compression mode.

Again, all this has been known for many years.

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