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TSMC experimenting with rectangular wafers vs. round for more chips per wafer
- johnea 2y agoThey are still going to have to cut the edges off of round waffers to make them square. The process of drawing the ingots leads to inherently round waffers. This is something that is not done by the foundary, but by a vendor.
- throwup238 2y agoThe spin coating process that applies etch resist also favors round wafers but if they've figured that part out, it's a win because their precision positioning equipment is limited to a square X/Y stage. With round wafers, they lose quite a bit of that space and the wafers are so cheap that wasting some edges isn't a big deal compared to the reduced overhead per chip.
- adolph 2y agoBy squaring the circle, they gain by holding less non-addressable space in the etching step?
- LeifCarrotson 2y agoWhy is the precision positioning equipment limited to a square stage? Or is it actually a rectangular stage? Couldn't they use an r-theta circular positioning system instead of linear? Their optics are fundamentally circular constraints, seems like that should drive everything else to a circle.
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- jjk166 2y agoSure but cutting down larger ingots only affects the vendor, and these rectangular wafers could be handled by the same (or at least similarly sized) equipment for all the other downstream processes. It's way easier than retooling everything to a larger circular diameter in one go.
- dist-epoch 2y agoCutting those edges is much much cheaper than throwing away incomplete chips at the edges.
- huppeldepup 2y agoI suspect they're going to start with a rectangular substrate on which they'll grow Si and then high electron mobility materials.
- pclmulqdq 2y agoMaking large silicon boules is cheap enough that I'm sure what they plan to do is just square off the sides of the boule before sawing into wafers. The scrap from that process, since it is pure silicon, can just go back into the pot the boule was drawn from (it might need some cleaning steps first), so there is effectively no wasted silicon.
- jagged-chisel 2y agoI would imagine, as it stands today, that packing rectangular chips into elliptical wafers has a certain amount of waste that can also be recycled. Actually, I suppose it would be less wasteful to fill the ellipse with rectangles up to the safe edge than it would to lop off entire sides of a boule to make a rectangle for filling. I don’t mean to insinuate you are wrong - I need an education on how this rectangle business is better. Maybe they’re just trying to remove the “lop the sides off” step?
- pclmulqdq 2y agoPacking rectangular chips onto circles has waste, but that waste cannot be recycled. It has been processed through a lot of different steps that contaminate it. I'm not sure if it gets recycled, but it's going to be a lot harder to recycle than large chunks of pure silicon.
- jagged-chisel 2y agoAh, makes sense. I hadn’t even considered the process of etching the chips. Pretty high contaminant-to-silicon ratio for sure. Thanks for answering!
- tonetegeatinst 2y agoIs their any blogs or videos about how these ingots are produced? The cost of blank wafers for a hobbyist is just so steep that im looking into making my own silicone blank wafers.
- numpad0 2y agohttps://en.wikipedia.org/wiki/Monocrystalline_silicon https://en.wikipedia.org/wiki/Monocrystalline_silicon
- ahazred8ta 2y agoPrices for 8 inch 200mm silicon wafers are under $50, and the smaller ones are even cheaper.
- pclmulqdq 2y agoLast time I checked (about 10 years ago), 300mm wafers of decent purity were about $20. If 200mm wafers are now $50, this is big business.
- HPsquared 2y agoWhat's the value of the completed chips from a 300mm wafer?
- pclmulqdq 2y agoNvidia GPUs are about $1 million per 300mm wafer. $100,000+ per wafer of chips is generally not out of the question.
- wolfi1 2y agohow would you achieve the purity you need?
- bbor 2y agoWe’re all just wasting time until someone figures out how to make wafers into shells that nest together into spheres, right? People talk about the end of Moore’s law and such, but we’ve still got a whole other dimension to work with… Gosh, if they let me handle this chip design stuff, I’d have it figured out in no time! Looks easy.
- bonzini 2y agoThat other dimension is the one we use to dissipate heat.
- Two4 2y agoWe should go 4D and start dissipating heat into the past.
- cpuguy83 2y agoWait... global warming... shakes fist at the future
- RheingoldRiver 2y agoAh, that's how the ice age ended
- xen2xen1 2y agoWell, the Earth was in a different point in space in the past, so it would not end up on Earth.
- PhilipRoman 2y agoInteresting idea, although if true then time travelling even a second earlier/later would likely put you several hundred km in the sky (or the ground). I guess any potential time travelling device would have a reference point located in itself, therefore prohibiting this effect.
- elcritch 2y ago
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- MrLeap 2y agoHexagonal chips when?
- s0rce 2y agoseems hard to dice
- haneefmubarak 2y agoIO OR L4$ triangle tiles, main chip hexagons
- pitaj 2y agoIt would only require double the cuts, right?
- ajb 2y agoThe problem with that is that you can't do it by making straight chord slices of the the wafer - each cut has to terminate or it will go through the middle of the next hexagon. But it does sound plausible - surely lasers could do this more easily than retooling the whole lithography pipeline for rectangular wafers. But you'd think they would have thought of the idea. You could do triangular chips with straight cuts. But I that would divide the area more finely, which is the opposite of what they need.
- azornathogron 2y ago
- robocat 2y ago> It takes the deep pockets of chipmakers like TSMC to push equipment makers to change equipment designs. I presume Apple invests in a lot of the capital costs? Apple needs to put it's cash somewhere and they can align that with exclusive contractual access to production of leading edge CPUs. Note that I haven't actually read anything about Apple's investment - I'm just hypothetically assuming it. We do sometimes hear about the exclusive contracts with TSMC. Fabs got too expensive: that was why Global Foundries was spun out of AMD. Intel now has similar problems as AMD did?
- wmf 2y agoI think Apple and Nvidia are prepaying TSMC which helps TSMC pay for capex. In other cases I've read about Apple owning machines used by their manufacturers.
- bostik 2y agoFor what it's worth, Apple has been doing that for ages. Back in 2007/2008 nobody could get their hands on a capacitive touch screens at any meaningful scale. Apple had bought the entire world's manufacturing capacity and 100% of the supply for about two years ahead. They showed with iPhone that it was possible to do multi-touch screens well - and the consumers took notice. "Pinch to zoom" was a product differentiator back then. What the consumers couldn't know was that nobody else could possibly match Apple's offering even with the best engineering workforce on the planet, because it was impossible to get hardware capable of multi-touch beyond tiny lab batch sizes. And you had to fight even for those.[ß] ß: I had the privilege of working directly for a Nokia fellow from 2007 until 2011, and got a ring-side view into the supply chain problems for high-end mobile devices. I also learned to dislike NXP with a passion, because that company has a funny habit of withholding spec sheets unless you are buying their SoC systems by the millions...
- wmf 2y agoI always wondered why the N900, which was designed in response to the iPhone, used a resistive screen. Supply chain would explain it.
- cyanydeez 2y agoIn britain theyte called chips
- bigblind 2y agoIt's insane that companies these days are getting rich selling chips that aren't even supposed to get fried.
- type0 2y agoyou can delid your CPU and fry bacon on it instead
- deepfriedchokes 2y agoThey’re called crisps.
- TanjB 2y agoNo, this is panels from which interposers will be made. Which are now larger than chips and rectangular, so wasted edges from a 300mm wafer are high. The proposed size is much larger than chip-grade ingots. They don't need perfect silicon. It can be grown on a continuous ribbon which is sliced into panel sizes like they do for solar cells. If they need a perfect surface they can deposit some pure Si to finish it. Maybe we will eventually see that replace ingots for chip grade.
- specialist 2y agoTIL https://en.wikipedia.org/wiki/Interposer https://en.wikipedia.org/wiki/Interposer The interposer is the layer between chips and their package. Per RTFA, TMSC is trying to fit more chips per interposer. Neat.
- mensetmanusman 2y agoSpin coating rectangles sucks.
- klysm 2y agoSpin coat as a circle then cut out a rectangle perhaps? I have no idea where the costs end up
- mensetmanusman 2y agoWhen you care about nanometers of thickness variation the gap always matters.
- logtempo 2y agoAt this point just keep going with circle wafers.
- LikeBeans 2y agoNot sure it's that of an issue but it's been a long time since I worked in this space. I can imagine a higher rate of spin with maybe a (large enough) circular plate underneath the square wafer would do the trick.
- justinclift 2y agohttps://archive.md/aWHFT https://archive.md/aWHFT
- kowalski7cc 2y agoWhy not hexagons?
- kowalski7cc 2y agoHexagons are the bestagons
- gnramires 2y agoRectangles are straight up simpler :)
- wdh505 2y agoSo how about a compromise and get interlocking triangles?
- enchanted-gian 2y agoi enjoyed that cgp grey video so much i rewatch it every few months
- klysm 2y agoI’d imagine most things are designed in rectangular constraints
- BluSyn 2y agoGood for tessellation only if chips are also hexagons. Arguably chips themselves could be hexagons for better pin density and potentially thermal properties. Surprised nobody has tried this before.
- Out_of_Characte 2y agoYou cannot cut straight lines trough hexagons. Triangles would work but would be even more inconvenient to design cut and process into normal chips. So squares it is.
- ginko 2y agoMy understanding is that round wafers are cheaper to produce since the silicon purification process produces cylindrical rods that are then cut into circular wafers. With fabrication becoming more and more advanced I can see that this original cost advantage of round wafers becomes less significant compared to everything else.
- newswasboring 2y agoOn a lighter note, this is actually a career threatening news for me. So much of my job is to figure out what to do with the end of the round wafer (partial dies), that I can't imagine what my whole department will do if we go for rectangular wafers :'). Made me realize how specific my engineering has been for the last 5 years.
- klysm 2y agoWhat do they do with the leftovers? I’m curious I mean even if they do start using rectangular wafers for _some_ things, there is so much supply chain momentum in circular wafers that surely you have some fairly significant job security.
- newswasboring 2y agoYou're right. But, I work in lithography, and there are only positives for going to rectangular wafers. We will be able to clamp is better, I think acceleration stresses will be easier to manage, modeling will be easier because it will be per field exactly the same, and so on. Litho industry (which basically means ASML at this point) might jump on this. But I'll reiterate I mean all this on a lighter note, don't think it will happen within my career :). Edit: Didn't read the question you asked in the first sentence. The left over parts are usually just taken along in the process till the end and are scapped when we get to the cutting stage. The problems arise because the structures on the partial dies are not the same as the full dies in the middle of the wafer. This causes a bunch of weird stresses on the edge and in my small corner of engineering we optimize the fuck out of the edge dies so their stresses are less weird.
- daniel_reetz 2y agoI'm facing an engineering problem that amounts to stresses accumulating on the edges of a layered substrate. Are there any references, process notes, books, or industry approaches that you could point me to? High level and/or general are OK.
- 2y ago
- smokefoot 2y agoThe industry moved to 300mm 25 years ago. It’s going to take a lot to get off that standard. Also, round chambers for etch and deposition are good for homogeneity. I can imagine square chambers would result in lots of process challenges.
- ngneer 2y agoI thought wafers were round in part because edges get damaged or contaminated in handling, and one would not want to have a real chip on the edge be damaged that way?