From Silicon To Microprocessors 174
prostoalex writes "Jim Turley from Embedded Systems Programming magazine answers the question of where microprocessors come from. While the public generally knows about the silicon and microprocessor vendors, few can describe the process of turning the beach sand into the latest and greatest several-hundred-dollars-worth CPU."
One supplier (Score:5, Informative)
I'd always thought these materials were made in hot, dry climates, like Arizona, yet there was a supplier right in my backyard.
Clean Rooms (Score:5, Informative)
For those of you that have never been in a clean room, there is a tremendous amount of ambient sound due to the very important air cleaning/circulation system. In order to make the clean room "clean", there can only be so much dust particles in the air. (e.g. 1ppm) (there are actually different classes of clean rooms)
The ramification of this is that one can hardly hear one's voice. Personally, I'm glad I'm not in the semiconductor field
Try Intel's museum (Score:5, Informative)
Re:...giant silver bolognas... (Score:5, Informative)
Misses one important point: yield. (Score:5, Informative)
And that is ofcourse why moving to a smaller technology (eg from
Re:near-first post (Score:3, Informative)
The term "3rd World" was coined to describe the rest of the world, after NATO and the Warsaw Pact nations, which were implied to be the first and second worlds respectively.
Although that definition didn't stick, the phrase did, and quickly came to take on the meaning that we all know, since most of the nations it included were desperately poor.
(Here endeth the history lesson
Re:Leaves out the meat... (Score:4, Informative)
But as far as an article targeted at a total layperson goes, it's okay. Not that most laypeople don't quickly lose interest when you start talking about wafers, masks, reticles, photoresist, process steps. You always have to start with the broader concepts and see when their eyes glaze over:
What do you do?
I work at a place that makes computer chips
Oh really? What kinds?
All kinds. I work in the ASICS group.
ASICS? Like the sneakers?
Re:Why just square chips? (Score:2, Informative)
Re:This doesn't make sense... (Score:5, Informative)
Projection blur (Score:3, Informative)
It sounds like they focus the center exactly and let it get blurry the further out you go (this is the case where the plane is tangent to the sphere -- a zero-radius circle of focus, which is of course a point). I would think they would set the cicle to be larger in order to get more area of better focus, but maybe having some blurring in the center screws up their designs more.
Dunno, IANAMCFA. (Dare anyone to figure out what that one meant.)
Too elementary... (Score:5, Informative)
Pure silicon chunks are actually made from condensing a very pure Silicon gas called Silane. The chunks are broken up, and melted in a very hot furnace, with a crucible made out of quartz(usually). Any doping, or impurities to give the silicon it's different electrical properties are added at this point. Boron (B) is fairly common.
Then, a nice perfect seed crystal of silicon is dipped into the molten silicon which starts to crystalize around the seed crystal. The growing crystal is turned and slowly pulled out of the liquid silicon as it grows to help keep it regular. The result is called a boule, or "the bologna looking thing"
As a side note, the doping is usually too high at the top of the boule, and too low at the end of the boule, so only about the middle 25% is used.
Then it gets sliced into wafers. etc. etc.
Mistakes? (Score:5, Informative)
(1) Silicon is not sand. Sand is silicon dioxide (well, most sand). It needs to be reduced (the oxygen needs to be removed) and purified. And purified. And purified. (I believe Brazilian quartz is actually the preferred stock for silicon dioxide, rather than sand, due to its purity.)
(2) Photo-resist does not need to be electrically conductive. It does need to be capable of resisting attack by whatever chemicals are next in the step (especially the HF). Since they're usually polymers that are either polymerized or depolymerized by the exposure, they generally are not conductive.
(3) Current generation laser steppers are not EUV. (They are UV, maybe DUV, being slightly less than 1/2 the wavelength of visible indigo.)
(4) One could get the impression that each chip on the wafer is processed separately at each step.
(5) Fabs and foundries are related but distinct entities. (I personally have worked in a fab, but never a foundry.)
(6) It's the mask that is imprinted on the wafer's photoresist, not the chip.
(7) Moore's law is incorrectly repeated. This is especially bad because it claims to be correcting the common belief (which it probably is). Moore's law was about the economics of chip density -- the most _cost effective_ density doubles every 18 months.
(8) I've usually heard and talked about individual die and multiple dice. (And breaking up wafers into chips is called dicing.) Maybe others call them (plural) die, but not everyone.
(9) The 200mm wafer area calculations are wrong. A 200mm wafer has a radius of 10cm; the area is therefore (10)^2*pi ~= 310cm^2. So one won't get 986 die from a square wafer and only 279 from a round one.
(10) Lots and lots of companies don't build their chips on the smallest feature sizes possible. Very few can afford to manufacture 90nm chips at this point, so the bulk of chip _designs_ are manufactured at
There are probably many more errors...
RJ
Re:Leaves out the meat... (Score:5, Informative)
To work in a bunny suit on the production floor? A high school diploma is often enough. To work in test/yield improvement? An EE degree, perhaps. To actually develop the bleeding edge processes? A PhD in physics.
There's far more to it than that, of course. And the actual chip designers could be across the parking lot or around the world.
Re:Why the clean rooms? (Score:2, Informative)
Also, mostly the machines are made by different vendors, so they don't have communication protocols to "talk" to one another, or to talk to a central dispatching control system. Therefore you need operators to move parts from machine to machine, and to select the appropriate programs to run on each machine (the parts pass through each machine multiple times, getting different processing each time).
Finally, the machines do break, and you want somebody there to intervene before several tens of thousands of dollars worth of parts get crushed.
Its not the laminar flow systems making the noise. (Score:5, Informative)
The materials used to produce semiconductors are extremely deadly to humans as are many of the process by products.
Pretty much every processing tool has multiple exhaust connections which remove potentially harmful fumes to a scrubbing system on the roof that removes the toxic chemicals which are then treated and disposed.
There are other noises from the tools and support equipment but I assume you thought it was the laminar air flow filtering system because it sounded like high volume air movement. They do move high volumes of air but you don't want the air moving too fast as it will stir up any particles that may be present in the room.
burnin
oh, I do work in a clean room, have since 1989.
Re:Why just square chips? (Score:3, Informative)
Re:near-first post (Score:2, Informative)
And, if it's history education we're after... Sauvy, a French demographer, is generally credited with the term. He wanted to convey how Third World countries are exploited by the first and second. It was an analogy dating to the French Revolution when the first two estates (clergy and nobility) exploited the third (the commoners).
Yield terminology wrong... (Score:2, Informative)
You are correct that smaller die sizes produce more die per wafer, however, shrinking the structures in a die's circuit make it more susceptible to failure due to contamination. Therefore you are actually wrong when you state that a smaller die will yield more.
You can think about it this way. If you have two parallel conducting poly lines that are seperated by an insulator that is 1 inch wide and you drop a penny on the insulator it is likely that the insulator will still work because the penny, which is the contaminant, is not large enough to short across the insulator. If you take that insulator and shrink it down to 1/4 of an inch and drop the same contaminating penny on it there is a chance that it will short the two poly conductors across the insulator and destroy your circuit. Take that same circuit and shrink it to 0.01 inch lines and suddenly your process that ran wonderfully is destroying every die on the wafer because the penny is guaranteed to short the circuit every time.
So what you can derive from this is two things. First, the smaller contaminating particles are the less likely they are to destroy a die and may actually be acceptable, the smaller a die gets the more likely it will be destroyed by smaller particles and you plunge into a never ending battle of cleaning up smaller and smaller sized particles.
Speaking from experience I watched a process that ran for 10+ years and worked fine. Once the geometries in the die shrunk to
burnin
Re:Why the clean rooms? (Score:2, Informative)
Manufacturers are able to completely automate the entire wafer handling process. The alignment for handling and processing is many times better than what any human could do.
And there have been standard communication protocols for interconnecting tools and systems for many years now. The two most common protocols are SECS and GEM.
burnin
Re:Mistakes? (Score:1, Informative)
some neat stuff, despite you are not being serious (Score:5, Informative)
* ingots are not always "grown." (think dipping candles) there is also a technique where you start off with a polychrystaline ingot and use localized heating to progressively monocrystalize it by localized melting. The technique is similar to one of the methods of removing impurities from iron bars.
* CMP is damn cool. I mean, it's nice and all hearing about "polish to within an atom" precision, but if you take a polished wafer, it would make the best mirror you'd ever own. Granted silicon is not the perfect reflective surface, but you won't get a mirror more accuratly shows every feature on your face. =) Otoh, when dusts and stuff DO get into the CMP machines, though, it scratches the wafer. Though you don't see it, when you trace failures on the wafer the failing gates would generally follow an arc shape (corresponding to the wafer and polishing head rotation), and from that you get the CMP machine checked out.
random junk I thought that was kinda neat.
** I used to know about 3 years ago but then I forgot. so don't expect like a correct answer or nothing.
heh (Score:1, Informative)