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Silicon Seduced From Silica
Roland Piquepaille writes "Making silicon is an expensive process, which conventionally involves carbothermal reduction, in which the oxygen is removed from silica by a heterogeneous-homogeneous reaction sequence at approximately 1,700 C. Now, Japanese researchers have developed a new technique which uses electricity to remove the oxygen from silica. Their technique is based on the immersion of silica in a bath of molten calcium chloride salt at 850 C, which should reduce the costs of making silicon -- and other elements, like zirconium. Check this column for a summary or read this article from Nature for additional details."
I was going to ask if this was going to make the price of breast implants drop low enough so that the procedure would be available to all the women that would want it; for example, to the point where one could simply hand out gift certificates. Then I realized that modern boobs are now just saline solution, and the high price must come from the "doctors" performing the procedure itself.
Mmmmm... Brine. Delicious brine.
Small potatoes make the steak look bigger.
If it's not obvious from the definition, silica is silicon dioxide, SiO2. It is the primary ingredient for making glass. IConsider it as purified sand - all the impurities that color the SiO2 have been removed.
Unfortunately, many of the conventional sand deposits (Floridian sand not exempted, I think) contains only a small amount of silica, making the refining process prohibitively expensive. This process might be a little cheaper, but proportionally speaking they're still going to do better with dredged volcanic "supersand".
Try not. Do or do not, there is no try.
-- Dr. Spock, stardate 2822-3.
reduce the costs of making silicon -- and other elements, like zirconium
Fake diamonds and fake racks drop in price, the pr0n wars begin! Scratching and clawing for territory, kicking for market share, it is an all girl-on-girl cage match!
Eve Fairbanks says I drive a hybrid!LOL
not related to silicon, but i like to point that out. in case people are looking for uses for zirconium =).
for those that thought about it - no spectra is not good enough for space elevator. only 3GPa tensile strength (steel about .25 for cheap ones and 5 for REALLY good ones). space elevator needs ~62GPa. nanotubes ~150GPa theoretical.
okay. end rant.
My life in the land of the rising sun.
Now prices can remain the same while profits go up...
"Times may change, but standards must remain the same." - George Carlin.
Obviously it will reduce the cost of silicon chips ... a little. In fact a 3 inch Si wafer costs about 3 USD. So you Intel Hexium Pro 10 GHz chip cost will not be much affected by this. However the solar power industry has often used Si cutoffs from teh chips industry, a kind of recycling and there the cost scale is very different.
As wafers have grown in size (and changed from inches to metrics), up to 300 mm production size today, it means there is effectively less cutoffs available to make cheap polycrystalline solar cells. Sure, mono crystalline solar cells are more efficient but also far more costly.
This new process then can mean a lot more cheap solar cells. Imagine like all available roof areas being covered, down to the top of all cars.
The cost of the silicon wafers has an enormous impact on the cost of silicon solar cells. If this cost can be brought down with this new technology suddenly solar energy becomes competitive !
Markus
This process involves turning one chemical compound (SiO2) into a pure element (Si)
Graphite and diamond are both pure carbon. You need those high temperatures and pressures to cause the atoms to rearrange into the crystal lattice of diamond.
retrorocket.o not found, launch anyway?
Actually, the Japanese had similar oxygen destroying technology since 1954, unfortunately, the discoverer Dr. Serizawa chose to commit suicide rather than risk having the technology made into a weapon. The technology was rediscovered in the 1990s, unfortunately, the manner in which it was re-revealed to the world led to unfavorable publicity. Only now has the furor died down enough for oxygen destroying technology to finally realize its potential.
Remember your chemistry? REG and LEO? Reduction is Electron Gain, Loss of Electrons is Oxidation
The fact that oxygen is being removed from the compound should have given you a clue.
Stick Men
btw - this kinda shows how bs was bush's little thing about saddam using ALUMINUM tubes for reactors.
My life in the land of the rising sun.
Hehe.. unless you find pure silicon somewhere, you will have to extract it from silicon oxide.. so, you don't make elements, you just extract them. BTW, 'making elements' is no longer called alchemy, it's called nuclear physics nowadays. :)
"It's too bad that stupidity isn't painful." - Anton LaVey
Therefore the collected silicon mus be remelted, drawn, cleaned, sliced into tiny placks, etched, washed and polished. However this is also has to be done with silicon obtained in other ways. Nowadays there are machines who can perform most of these procedures in one run.
A short explanation of this can be found here
I don't know how much the raw silicon costs, but I suspect that most of the cost of the wafers comes from this month-long crystal growth and planarization. Good (ie, very flat) 200mm silicon wafers for semiconductor production can cost up to $1000 each, although they are probably much cheaper now due to lack of demand. Many processes also don't require the flattest wafers and so one can get by with wafers that cost a small fraction of that.
Only a small fraction is actually turned into wafers, and the expense in that process has less to do with turning silica into silicon, but turning impure silicon into really, really pure, single crystal silicon. [It's actually a really cool process, I wish I could remember the details. It involves bonding the silicon to something, and distilling it.] And this cost is very small compared to the cost of turning a wafer into chips.
This discovery, if it actually saves money, will have some impact on the steel industry, but practically none on the semiconductor industry.
It's not wasting time, I'm educating myself.
Zirconium is in the same column in the periodic table so I think it is possible that the researchers are thinking about Titanium too, because it is expensive to produce with the process available and with high potential of money return.
Hmm, last I checked Spectra 1000 has tensile modulus of 172GPa (older version, Spectra 900 is at 117GPa or so) and steel averages around 210GPa... I wouldn't call that a huge difference. certainly more than half as you claimed.
.97 (water at 1) and steel 7.8 or so...
impressive especially considering spectra has specific weight of
I mean, I can't imagine that if cost wasn't a consideration, any places where you wouldn't want a lighter material vs. the heavier one (except that polyethylene is not good with fire, so car engines are out).
but i digress. steel is cheap. but damn, as far as materials go, spectra is about the sexiest we got right now (that's mass-producable, anyway).
My life in the land of the rising sun.
Actually, most volcanic sands don't have much quartz at all, and here is why. If it has been derived from a basaltic volcano (ie Hawaii), the composition of the sand will be extremely high in mafic (very silica poor) minerals since the source magma was low in silica. Then, if you are talking about a volcano whose melt composition is closer to the felsic (silica rich...so much so that you get quartz precipitating) side, these are typically very explosive volcanos that produce lots and lots of fine grained ash but no lava flows to weather from. What you *really* want is a sand eroding from an exposed granite. You get great big fat quartz crystals, and feldspars that turn to clay very quickly. And that's just if you want to find a loose sand that will be quartz rich. What I would do is actually get a hold of some mining rights out in the Southwest US somewhere and start a quarry operation on all the excellent quartz sandstone they've got.
Project Steve
There's something ironic about that... ;)
Would discovering that the diamond is fake be grounds for having the marriage annulled?
Silica is the primary component of the Moon's surface (and Earth's too) - this technique could greatly reduce the cost to produce useful things (like oxygen as a fuel component and for life in space, and silicon for solar cells) out of bulk lunar material.
Large-scale space construction is coming, and will provide one of the major markets for lunar materials. Martin Rees has a new book out that is pretty clear on why we need to develop space resources. Here's another enabling technology - now let's go do it!
By the way, anybody in the SF bay area this coming weekend should check out the International Space Development Conference in San Jose, where we'll be discussing a lot of these ideas, and more!
Energy: time to change the picture.
They have been doing this with aluminum for decades. They put aluminum oxide in molten sodium aluminum floride and use electricity to seperate the oxygen from aluminum. I'm suprised that a similar technique for silicon was just recently invented.
WOW, a subject where I seem to be the first "expert" to post.
I work in the semiconductor industry. (actually, for one of he largest producers of semiconductor-grade silicon in the world,) and I'm intimately familiar with the process to turn silicon from sand into wafers for chip manufacture. At my work, we are the middle step. I'll explain:
Semiconductor-grade silicon is ultra-pure silicon metal (I mean parts-per-billion atomic purity.) All the semi-grade Si in the world is produced in approximately the same way.
Silica (sand) is reduced to "metallurgical grade" silicon (~99.5% pure) in an arc furnace process, the sand is melted with a reducing agent (often carbon), and the molten metal is poured off. (this is a very cool process. The smelter has a hole in the bottom that is allowed to freeze shut with Si, and when they're ready to pour, someone shoots out the Si plug with a shotgun. Cool job)
This metallurgical grade Si is sold to intermediate producers who grind it to a fine powder, and react it with gaseous HCl in fluid bed reactors to generate chlorosilanes (H3SiCl, H2SiCl2, HSiCl3, SiCl4.) These chlorosilanes are then distilled to very high purity ~99.999% or more.
The chlorosilanes (different ones for different manufacturers) are then used in the Siemens process to produce semiconductor-grade POLYCRYSTALLINE silicon. The process works by Chemical Vapor Deposition. Ultra-pure silicon rods are placed in a reactor in an inverted U shape, and each end of the U is connected to an electrical circuit. The atmosphere inside the reactor is purged of all gasses and then chlorosilane vapors are introduced. Huge amounts of electricity are used to heat the U circuits to incandescence (imagen a 600 megawatt lightbulb) and the ultra-pure chlorosilanes decompose into Si and HCl at the surface of the rods.
The problem with the silicon, at this point, is that it's polycrystalline, not single crystal. In order to produce proper IC's, the crystal structure of the silicon must be perfect 1,1,1 crystal. Polycrystalline silicon (a.k.a. poly) is a random oriented growth where the crystal structures of many crstals have grown together. The poly is reduced in size and sent to a crystal pulling facility (wafer fab) where it is used in the Czoralski process for making wafers.
The CZ process consists of melting a large amount of poly, then dipping in a "seed" crystal. This perfect single-crystal specimen is "dipped" into the molten silicon while being rotated. The seed is then carefully "pulled" upwards while rotating, and the resulting ingot grows in diameter based on the pull speed, and several other factors (300mm is current state of the art.)
Once the pull is completed, a ~1000+ kg log of single crystal silicon is made, and is ready for final processing to wafers. The tapered ends are removed (top and tail) and the "log" is shaved down perfectly round and to the proper diameter. Diamond impregnated wire saws are used to slice the log into wafers, the wafers are lapped and polished, and they are ready to have IC's printed on them. (some are further processed, but you get the gist.
HTH
GM