[HN Gopher] Researchers uncover the fastest semiconductor yet
___________________________________________________________________
Researchers uncover the fastest semiconductor yet
Author : g0xA52A2A
Score : 152 points
Date : 2023-11-09 05:48 UTC (17 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| mareko wrote:
| "This means processing speeds in devices based on them could
| reach femtoseconds, a million times as fast as the speeds
| achievable with current gigahertz electronics"
|
| That seems like quite the discovery.
| happytiger wrote:
| > "Now that we know what structural and electronic properties
| are needed...there is good likelihood that we will find earth-
| abundant alternatives to this rhenium-based material."
|
| Unfortunately the rarest of rare materials, but the above quote
| does point out that it shows us what's possible even if it
| isn't viable yet.
| timthelion wrote:
| Rhenium is used in industry already in metal aloys. It costs
| around $10000 per Kg. [1] And the US produced 8 tons of it in
| 2020 [2]. A modern cpu weighs 60g. If we were to make CPUs
| out of pure Rhenium we could make 133 000 a year at a cost of
| just $600 each for raw materials. If these things are really
| a million times faster than the current best in breed silicon
| ones they will have no trouble competing commercially. $600/
| one million is not very much money at all and 133000 times
| one million is a LOT of compute. Furthermore, the CPUs will
| not be pure Rhinium.
|
| [1] https://en.m.wikipedia.org/wiki/Rhenium
|
| [2] https://www.statista.com/statistics/1312513/rhenium-
| producti...
| bpye wrote:
| Also depending on how easily you can scale these
| semiconductors down, you may not need such complex cores.
| CPUs today are complex to (amongst other things) improve
| IPC - but if you're really talking a 10^6 improvement in
| clock speed, I would guess that even a simple in-order core
| would perform better, and be much smaller.
| speed_spread wrote:
| DRAM latency will remain a problem, no way you can make
| CPU a million times faster without bringing in memory on
| the same chip. And you could probably only have a few kB
| close enough to the core to keep up in frequency.
|
| Most probably you'd see this tech in highly specialized
| interfacing circuits, like current GaAs chips.
| I_Am_Nous wrote:
| Fiber optic regeneration could benefit from faster
| electricals on longer shoots, you can only amplify so
| many times before the noise is amplified too much to
| ignore so they use optical to electrical to optical
| circuits. A much faster electrical path could make for
| some really cool high speed regeneration.
|
| I can also imagine Juniper using them in an ASIC and
| charging a ton.
| seszett wrote:
| That's not really how market works though, if you could
| make processors that were a million times faster than
| current ones, there would be demand for much more than 133
| 000 a year and many people would be ready to pay more than
| 600$ for them. For comparison, I find on a random Google
| result that 50 tons of silicon are used per year for CPUs
| "in the US".
|
| The price of rhenium would skyrocket to million dollars per
| kg, and as long as production would stay the same (assuming
| it's limited by raw resource availability rather than just
| extraction methods) it would keep getting higher.
|
| The current relatively low price of rhenium (relative to
| its rarity) is simply due to low demand.
| mhb wrote:
| And when the price of something goes up, it is more
| rewarding to find and process more of it.
| runeks wrote:
| You seem to be reversing cause and effect.
|
| Sure, assuming (1) we can actually produce a rhenium CPU,
| and (2) we are unable to increase the production of
| rhenium then, yes, the price of rhenium will increase.
|
| But it will increase precisely because we have a working
| rhenium CPU in production in the first place, which is
| what the article disputes is possible (due to its current
| rarity).
|
| Furthermore, the price would skyrocket only if people are
| actually willing to pay a high price for these rhenium
| CPUs, which again means they're worth the money.
| lazide wrote:
| At a million/kg, new methods of production would
| definitely be found. Even if it was some kind of neutron
| bombardment element synthesis.
| chmod775 wrote:
| > The current relatively low price of rhenium (relative
| to its rarity) is simply due to low demand.
|
| For stuff previously needed in low quantities it's
| usually the reverse - price goes down as more is needed.
| Initially prices are high because manufacturing equipment
| has to be maintained even if idle, wages have to be paid,
| and because of logisticical overhead for the small
| quanitites. A second price drop occurs as we get into
| mass-manufacturing and better processes are found.
|
| Rhenium is a byproduct of mining and refinement, but I
| suspect it is often not captured because the small
| quanitites needed don't make it economically interesting
| - you would invest in infrastructure to extract it and
| immediately crash the price. That would change if there
| was a stable demand of higher quantities.
| maeln wrote:
| This ignore the law of offer and demand. If the supply
| doesn't change, but there is a lot more demand because now
| the semiconductor industry also want some, the price will
| shot up.
| jiggawatts wrote:
| Gold was extensively used in chip manufacturing previously,
| and wasn't cost prohibitive.
|
| The 60g figure is for the _packaging_ , not the chip. The
| actual chips are tiny and weight much less than that,
| probably under 1g for most processors.
|
| This new semiconductor isn't pure rhenium, it's a compound,
| and hence less than 1g would be needed, or about $10 per
| chip, maximum.
|
| Realistically, this new semiconductor would be deposited as
| an extremely thin layer on top of something cheaper like
| silicon or quartz. The material cost per chip would be
| measured in cents.
| adrian_b wrote:
| The cost of depositing an expensive substance like a
| rhenium compound on a semiconductor wafer is
| significantly greater than that of the substance that
| remains deposited on the wafer.
|
| Depending on the kind of deposition method used, for
| depositing a certain amount on the wafer, a much greater
| quantity is used, which ends deposited on the equipment,
| or as chemical precursors mixed and reacted or unreacted.
|
| Due to the rhenium cost and scarcity, all the rhenium
| compounds that are not deposited on the wafer must be
| recycled. That can raise the cost a lot.
|
| Finding a compatible substrate for deposition, with an
| appropriate crystal structure, can be very difficult.
| happytiger wrote:
| That's extremely interesting. So there is a considerable
| manufacturing process waste factor that reduces yield.
|
| I had been thinking that viability of yield could be an
| issue too as it would have the same wafer fabrication
| yield, wafer sort yield, and packaging yield that silicon
| does. _And_ as a new and profoundly expensive material
| there is going to be an appreciable learning curve.
|
| Is that what you're referring to? Or is there more to it
| even than that?
| tuyiown wrote:
| Economics works in dynamics.
|
| If desirable CPUs are made of Rhenium with an effective
| production line and that the raw supply is so tight, the
| price certainly won't stay at $10000/Kg, and probably will
| align with equivalent computation power/watt of traditional
| designs. Any investor will see that it will only make miner
| rich without that much return miles aways, and walk away.
| runeks wrote:
| > It costs around $10000 per Kg.
|
| No, your source clearly says that was its peak price in
| 2008/2009, after which it fell to ~$3000 in 2018, and in
| 2020 it was $1000/kg [1].
|
| [1] https://pubs.usgs.gov/periodicals/mcs2021/mcs2021-rheni
| um.pd...
| adrian_b wrote:
| The $1000/kg was a minimum due to the reduction in air
| traffic caused by COVID-19.
|
| It is unlikely that the rhenium price will ever return to
| that value.
|
| The problem is that there are no chances of greatly
| increasing the production, so any new application will
| increase the price.
| Almondsetat wrote:
| The rarest or rare material can still be used in extremely
| specialized applications though
| Simran-B wrote:
| They also seem to say that it cannot be used directly for
| improving CPUs as they are designed today:
|
| > "[...] they are not necessarily compatible with current
| hardware used in the semiconductor industry," [...] the
| applications for these semiconductors "would likely be
| different than those for traditional semiconductors."
| quietpain wrote:
| processing speeds in devices based on them could reach
| femtoseconds
|
| That would also mean switching times that allow rectifying
| infrared light. I.e. capturing light energy with um-sized
| antennas instead of bandgap traps.
| tomalaci wrote:
| I remember when people were super excited for graphene and
| nanotubes in semiconductors. What happened to that? Seems like a
| lot of things stop dead in its tracks when it comes to mass
| manufacturing.
| WJW wrote:
| Mass manufacturing is really hard, it's not really a surprise
| that many things that we can do on lab scale can't be made to
| work (in an economical fashion) at mass production scale.
| adhesive_wombat wrote:
| We're incredibly lucky that copper and silicon are so
| (relatively) easy to work with.
|
| Imagine if even basic electrical systems needed wires made of
| rhodium and semiconductors only worked at cryogenic
| temperatures. We'd never have gotten over the "technological
| activation energy" in the 1800s.
| WJW wrote:
| For sure. When you look at a used car lot or a smartphone
| for a few hundred dollars, it is easy to forget that they
| are the product of a system involving (at least!) hundreds
| of thousands of people working together in a system that
| has been studied and optimized for decades. Maybe we'll
| eventually reach consumer grade graphene processors, but if
| we do it will probably take decades for the technology to
| advance through the technology readiness levels.
| amelius wrote:
| I think about this sometimes. Also, what if Pythagoras'
| formula didn't exist or was some king of hypothesis or a
| very long formula: where would technology be?
| lizknope wrote:
| Copper was not always easy to work with in semiconductor
| chips. When I started in the industry in the 1990's all the
| wiring was aluminum. Articles about copper for wiring were
| research projects and which company would be the first to
| get it to mass production.
|
| IBM was the first in 1997 and then others followed.
|
| https://en.wikipedia.org/wiki/Copper_interconnects
|
| That's how technology is. Things start out hard and with a
| lot of work and time we invent new methods. Aluminum was
| once worth more than gold. Then we invented new processes
| of extraction and refinement.
|
| https://clintonaluminum.com/aluminum-was-once-worth-more-
| tha...
| magicalhippo wrote:
| Asianometry recently released a nice video[1] going into
| the transition to copper interconnects.
|
| [1]: https://www.youtube.com/watch?v=XHrQ-Pmvwao
| gosub100 wrote:
| Can I ask an un-related question? In a CPU with thousands
| of pins, how come they use N pins for ground, N pins for
| VCC, when it seems simpler to have continuous bar-shaped
| contacts? Then pins would only be necessary for signals
| that actually changed. I see this in computer power
| supplies as well, they use N separate wires to carry V+
| and N more for GND, but if you need more current why not
| use a thicker wire and only have 2?
| dmoy wrote:
| > In a CPU with thousands of pins, how come they use N
| pins for ground, N pins for VCC, when it seems simpler to
| have continuous bar-shaped contacts?
|
| I can't speak to cpus with thousands of pins, but with
| significantly smaller chips that often have N>1 vcc or
| ground, it's typically due to layout convenience. The
| multiple vcc may be on e.g. opposite sides of the chip,
| and that makes it easier to route a pure vcc signal to a
| spot that needs it. It's easier to route outside the chip
| than inside the chip, because there's more space.
| mrWiz wrote:
| Additionally, there's also a benefit to standardization.
| Adding different pin styles makes the part harder to
| design and manufacture.
| Thetawaves wrote:
| This improves the impedance of high speed signal
| transmission - at high speeds the currents want to flow
| through the ground path as close to the signal path as is
| possible. Said another way - designers work to reduce the
| total area inside the electric circuit to support high
| switching speeds. The additional power pins in high pin
| count chips serve to reduce the distance between high
| speed signal paths and their return ground paths. This is
| actually true for both ground and vcc, but is easier to
| visualize when working with signals and their grounds.
| undersuit wrote:
| > if you need more current why not use a thicker wire and
| only have 2
|
| How do you route that current in one pin to the two
| locations the two pins handled? You've just moved the
| point where the split happens from on the motherboard to
| on the chip package.
| gosub100 wrote:
| you could have 2 bus bars around all 4 sides of the CPU,
| and tap off them at the point where the die has its
| connectors to the "body" (enclosure?) of the package. All
| the die pics I've seen, the tiny gold signal wires still
| route around the edges (i.e. they don't join the die in
| the center). So a thicker bus should work for the main
| voltage supply. But as the sibling commenter said, it has
| to do with signal impedance.
| lizknope wrote:
| You are looking at wire bonded chips. Wire bonding is
| still used for chips in older process nodes and lower
| number of IO. This article says up to 800 IOs
|
| https://semiengineering.com/wirebond-technology-rolls-on/
|
| But all the high performance chips in leading edge
| process nodes like 3nm are flip chips. The last time I
| worked on a wire bond chip was in 130nm in 2004.
|
| With a wire bond chip you can only have IO for signals
| and power/ground around the periphery. Some wire bond
| chips have 2 rings of IO pads but it makes the wire bond
| angles complicated. It's difficult to jump over other
| wire bonds to get closer to the center.
|
| https://en.wikipedia.org/wiki/Flip_chip
|
| Flip chips have a series of bumps above the top layer of
| the chip. These bumps are then connected to a small PCB
| inside a package or some other kind of interposer.
|
| The transistors are on the bottom of the die and then up
| to 18 layers of metal are built on top. In a wire bond
| chip the heat has to go up through all that metal stackup
| which is usually encased in a glob top which isn't great
| for heat transfer.
|
| https://www.gluespec.com/blog/glob-top-encapsulation
|
| In contrast a flip chip has the die mounted upside with
| the top layer mounted to the PCB and the side with
| transistors is on top and can be directly mounted to a
| heat sink. Intel and AMD used to have bare die around
| 2000 but then mounted heat spreaders on top because
| sometimes people would mount the heat sink incorrectly
| and crack the corner of the die when tightening down non-
| uniformly.
|
| http://mantravlsi.blogspot.com/2014/10/flip-chip-and-
| wire-bo...
|
| With a flip chip we can have over 15,000 IO in the chip.
| The flip chip bumps can be all over the die not just the
| periphery. Not only can we put IO in the center but the
| density of the bumps can be much higher compared to the
| pad points where a wire bonder would attach.
|
| As for your original question about some kind of
| continuous bar shaped contact we have a power grid
| underneath on every layer to distribute the power across
| the chip. This has to go from the top layer Metal18 down
| through vias to the transistors below Metal1.
|
| Modern chips have multiple voltages in multiple voltage
| domains. The DDR and PCIE sections have their own voltage
| requirements. The standard cells that are the combination
| logic within a CPU operate on much lower voltages. We
| have dynamic voltage control where the voltage is lowered
| to save power. We have voltage islands where the USB port
| can be shut off if nothing is plugged in or CPU core 1 is
| active while cores 2-4 are off saving power. This
| requires dedicated power / ground bumps and head switches
| to disconnect power to sections of the chip.
|
| I don't think we could manufacture your concept of a "bar
| shaped contact" because the process DRC (Design Rule
| Check) stuff is very rigid about what can be
| manufactured. Certain shapes, widths, and turns decrease
| the yield so they aren't allowed.
|
| https://www.vlsi-expert.com/2014/12/design-rule-
| check.html
| adhesive_wombat wrote:
| Perhaps not trivial in chip interconnects, but it's
| fairly abundant and a rather workable material in general
| (hence the bronze age). Faraday probably wouldn't have
| gotten very far if copper was a gas at room temperature
| or only occured in trace amounts and there were no other
| ductile, solid conductive materials on Earth.
| lazide wrote:
| Sure, though carbon and salt water is also reasonably
| conductive.
|
| Power distribution via hydraulics instead?
| undersuit wrote:
| I think they're talking about copper electrical wiring
| not semiconductor use. If we couldn't use simple copper
| to bootstrap our energy intensive aluminum industry in
| the 1800s we might be using rhodium.
| da_chicken wrote:
| It's also turned out that carbon nanotubes are toxic in a
| similar fashion to asbestos. While a completed chip would be
| sealed, it does raise concerns about the safety of
| manufacture. Similar concerns have been raised about
| graphene.
| runeks wrote:
| I'm not convinced that's a problem, since chip fabs require
| people to wear cleanroom suits anyway.
| da_chicken wrote:
| It's possible, but cleanroom suits are primarily designed
| to protect the product from the employees. They keep
| foreign contaminants out of the manufacturing
| environment. They're not necessarily capable of
| protecting the employees from the hazards of the
| manufacturing environment itself, nor do they necessarily
| account for the removal of hazardous material before
| venting the production area to the atmosphere. It might
| further add to the costs of the fabrication facility.
| lazide wrote:
| Adding hepa filters on exhaust (and issuing respirators)
| and not just intake would not budge the cost of a chip at
| all.
| DeepSeaTortoise wrote:
| I can't help but assume that anything being described as using
| graphene, carbon nanotubes, crypto, blockchain, bitcoin and -
| to some degree - AI is a scam.
|
| I feel like the only person I've heard talking about graphene
| and actually demonstrating any practical application is Robert
| Murray-Smith. This guy is like he fell down the popular science
| rabbit hole 20 years ago and emerged naked but for a towel
| screaming "Eureka".
| Teever wrote:
| That's utterly preposterous.
|
| I work with a company that has a couple of patents on a
| carbon nanotube based sensing system for hydrocarbons. This
| company is making and selling units every day, like this shit
| is real man.
|
| These units are installed out in the field all around the
| world and are tied into a dashboard for customers to see if
| any of their projects are experiencing leaks.
|
| I agree that the carbon nano-tech revolution that we were
| promised by pop-sci writers hasn't materialized but that
| doesn't mean that it isn't a genuinely useful substance.
| formerly_proven wrote:
| Nanotubes perhaps not, but Si nanowires and -sheets are being
| used for the channel in 3nm-class processes with gate-all-
| around structure.
| ajuc wrote:
| First steam turbines were made in ancient Rome. Took us almost
| 2000 years to commercialize them :)
| navi0 wrote:
| TIL the Romans invented the first steam engine but didn't
| seem to grasp its revolutionary potential and used it mostly
| as a party trick:
|
| https://en.wikipedia.org/wiki/Aeolipile?wprov=sfti1
| lazide wrote:
| Why automate/industrialize when you have literal slaves?
| phkahler wrote:
| >> TIL the Romans invented the first steam engine but
| didn't seem to grasp its revolutionary potential and used
| it mostly as a party trick
|
| I guess they were civil engineers, not mechanical
| engineers.
| scythe wrote:
| Wikipedia's history of this is very nice:
|
| http://en.wikipedia.org/wiki/History_of_the_steam_engine#Pre.
| ..
| Symmetry wrote:
| Normally a manufacturing process is doing well if 90% of the
| chips on a wafer are usable. Carbon nanotube based circuits
| manufacture are doing well if 90% of transistors were working.
| That needs to be solved before they're practical.
| hinkley wrote:
| Did we ever categorically prove that nanotubes aren't the next
| asbestos? That's not a small problem.
| I_Am_Nous wrote:
| Looking into this a bit and I discovered I have carbon
| nanotubes in my house already [1] and I never would have
| guessed. Since the nanotubes are pure carbon, I'm not sure it
| would cause a similar immune response to asbestos, but the
| "black lung" issue is still likely a risk. Lungs don't like
| powders in general.
|
| 1.https://en.wikipedia.org/wiki/Nano_tape
| seiferteric wrote:
| Well it depends, if you plan on grinding your semiconductors
| into dust and inhaling them, then yes its a problem.
| phkahler wrote:
| >> Did we ever categorically prove that nanotubes aren't the
| next asbestos?
|
| I'm pretty sure we know they are the next asbestos. So we
| won't do things with them that tend to produce a bunch of
| dust for people to inhale.
| itsthecourier wrote:
| Yes, it is expensive if you want millions of chips, but imagine
| those militar and trading operations who would be willing to pay
| for that speedup as an edge, hope they manufacture something
| soon. I just wonder how resusable is stuff like EUV when you
| change the semiconductor material...
| kragen wrote:
| there are lots of ridiculously expensive materials that are
| economic to make microelectronics
|
| you're probably reading this on a device that uses motherfucking
| hafnia for its dram dielectric
|
| i mean admittedly hafnium is still a thousand times as abundant
| as rhenium
| xeonmc wrote:
| Could this mechanism possibly be related to the Boson Peak
| anomaly in disordered materials? Potentially extra acoustic
| excitation mode caused by interactions of transient large-cluster
| vibrations.
| dstuessy wrote:
| Any thoughts on how manganese and technetium seem to share
| similar properties to Rhenium?
| https://en.wikipedia.org/wiki/Rhenium
| adrian_b wrote:
| Technetium has very similar properties with rhenium, but as its
| name says it must be made artificially, because due to its low
| lifetime all that has existed when the Solar System has been
| formed has disintegrated a long time ago.
|
| Manganese has significantly different properties (due to
| smaller atomic size and greater electronegativity), so just
| substituting it in the same chemical formula would not create
| the same crystal structure and any properties would be
| different.
|
| Nevertheless, it is likely that other substances with similar
| properties will be found, but it remains to be seen if any of
| them are stable enough and cheap enough to be used in practical
| devices.
| dist-epoch wrote:
| > One major problem that Re6Se8Cl2 faces is that rhenium is one
| of the rarest elements on Earth. This makes Re6Se8Cl2 very
| expensive and unlikely to ever make its way into a commercial
| product.
|
| Something doesn't add up.
|
| Rhenium price seems to be $2k/kg. Gold price is $62k/kg. Silver
| price is $0.8k/kg. So Rhenium is about 3 times as expensive as
| silver and 30 times cheaper than gold.
| lstodd wrote:
| I guess it's because there isn't much demand. If this takes
| off, prices will too.
| brudgers wrote:
| My understanding (from binge watching Asianometry) is that the
| rare earth metals are not mined directly.
|
| Instead they are extracted from ores in the tailings of large
| scale mining operations like coal or copper and refined by
| specialty processors.
|
| It is not commercially viable to mine the rare earth elements
| on their own. Because the price is only $2k/kg, it makes more
| sense to build a business around all the coal (or whatever)
| that has to be moved to get a kg of a rare earth.
|
| Because you still have to move all that dirt.
|
| Basically, the price reflects only the costs of refining,
| marketing, and distribution. Extraction is sunk cost.
| runeks wrote:
| > Rhenium price seems to be $2k/kg
|
| Based on what?
| onetimeuse92304 wrote:
| > One major problem that Re6Se8Cl2 faces is that rhenium is one
| of the rarest elements on Earth. This makes Re6Se8Cl2 very
| expensive and unlikely to ever make its way into a commercial
| product.
|
| I call BS. It is rare, true. But it is found in reasonable
| concentrations in some minerals (alongside molybdenum) that are
| already being mined and we just need to learn to extract rhenium
| out of it. For high perf semiconductors you only need microscopic
| amounts of it anyway.
|
| As to costs, majority of the costs are not in substrates anyway,
| however costly they are. The costs are in IP and in processing. I
| suspect even if silicon was as expensive as gold it would not
| meaningfully change the cost of current high-end CPUs that go
| into our phones.
|
| (edited, I mistakenly wrote ruthenium where I meant rhenium)
| foobarian wrote:
| Ruthenium is a bit different than Rhenium. But either way you
| can get it online. https://www.rwmmint.com/products/rhenium-
| metal
| onetimeuse92304 wrote:
| I meant rhenium. Don't know why I wrote ruthenium, that is
| obviously a mistake. Thanks for pointing it out.
| foobarian wrote:
| I am glad you did because it led me on a Wiki chase and I
| learned new things :-)
| readthenotes1 wrote:
| Did you see some dishes no longer moldy?
| xwdv wrote:
| Why would someone buy this? What can you do with a Rhenium
| ingot?
| runeks wrote:
| You can build the fastest semiconductor yet
| adrian_b wrote:
| You can be amazed of its density, but that is safer to do
| with the lighter, but much cheaper, tungsten.
|
| Most chemical elements with atomic numbers equal or greater
| than that of lutetium are very slightly radioactive (with a
| few exceptions like iridium, gold, mercury and lead).
| Rhenium is one of the most radioactive of them, but it is
| several orders of magnitude less radioactive than thorium
| and uranium.
|
| Nevertheless, its radioactivity is so weak that it can be
| handled safely with bare hands. Even so, making some
| jewelry kept permanently on the skin is unlikely to be a
| good idea.
| Gare wrote:
| > Rhenium is one of the most radioactive of them, but it
| is several orders of magnitude less radioactive than
| thorium and uranium.
|
| Rhenium does have one stable isotope, which comprises
| 37,4% of naturally ocurring Rhenium. 62,6% is radioactive
| Rh-187 with a half-life of 10^10 years. That's a bit
| longer than U-235 or U-238.
|
| But unlike uranium, Rh-187 decays into stable osmium.
| foobarian wrote:
| Once you have a periodic table display case, you would be
| amazed at how compelling it becomes to shop for element
| samples.
| fnordpiglet wrote:
| Hodl in case it becomes the next great semiconductor
| substrate?
| adrian_b wrote:
| Its concentration in minerals is not reasonable, but extremely
| small.
|
| The yearly production per human is a barely visible grain with
| a volume of about a quarter of a cubic millimeter. If each
| human would want to have a ring of rhenium, that would need all
| the global production accumulated during one thousand years.
|
| All of it is heavily contended for various applications like
| gas turbine blades, so the price is in the same range as for
| platinum-group elements, which are in fact much more abundant.
|
| If the semiconductor layers would have thicknesses in the tens
| of nanometer range, i.e. they would be deposited on some
| crystallographically compatible substrate, then such a
| semiconductor might be usable for expensive devices.
|
| Nevertheless, developing a deposition method that can recycle
| all the non-deposited rhenium may be not easy. The deposition
| methods normally used frequently deposit far more substance on
| the equipment walls than on the semiconductor wafer. When
| depositing pure inert metals like gold or platinum, there are
| relatively easy methods to recover them, e.g. by dissolving in
| acid everything else. Such a complex substance containing
| rhenium might be obtained from a chemical reaction during the
| deposition, but it may be difficult to find precursors that are
| also easy to recycle.
| runeks wrote:
| > All of it is heavily contended for various applications
| like gas turbine blades [...]
|
| Then why does it only cost $1 per gram?
|
| [1] https://pubs.usgs.gov/periodicals/mcs2021/mcs2021-rhenium
| .pd...
| adrian_b wrote:
| That low price was only in 2020, as a result of the huge
| air traffic decrease caused by COVID-19.
|
| The price of rhenium fluctuates wildly and a few years ago
| there was a maximum at $10 per gram.
|
| It is unlikely that it will ever return to the COVID-19
| price.
|
| The problem with rhenium is not the current price, but the
| minuscule production, for which there is very little hope
| that it could be increased much.
|
| If instead of being used in a few military and commercial
| airplanes and in a few industrial applications, like
| thermocouples or catalysts, there would be demand to use it
| in something used by everybody, the price would increase
| quickly.
| mrWiz wrote:
| Why do you think there's little hope on increasing
| production?
| lazide wrote:
| At $10/gram, of course there isn't much production?
| datadrivenangel wrote:
| Price of gold is ~$60/gram, so this is not especially
| expensive in the grand scheme of rare metals even if it's
| significantly more expensive than copper.
| lazide wrote:
| Considering its rarity and industrial usage, it's quite a
| steal even.
| runeks wrote:
| > If instead of being used in a few military and
| commercial airplanes and in a few industrial applications
| [...]
|
| Wait, above you said it's heavily contended...
| fnordpiglet wrote:
| Presumably given its scarcity any application makes it
| heavily contended
| onetimeuse92304 wrote:
| Here, I see the problem with your logic.
|
| > The price of rhenium fluctuates wildly and a few years
| ago there was a maximum at $10 per gram.
|
| You lost sight of the simple fact I mentioned, you only
| need a very small amount of it and you add it to a CPU
| that costs hundreds of dollars already. So the impact on
| the cost of the CPU would be negligible.
|
| Even at the highest cost of rhenium _you_ have mentioned,
| even if you needed a full gram of it (which I don 't
| believe, this is going to be more like milligrams or even
| micrograms), you still only change the cost of the CPU
| slightly, at most.
|
| This before you account for inevitable improvements in
| obtaining the Rhenium itself.
| marcosdumay wrote:
| The GP's point is that if people start using enough of
| it, the price will easily explode into several thousands
| or even millions per gram.
|
| It all depends on a lot of details that haven't yet been
| quantified here. And the recycling the GP talks about is
| a huge one.
| josaka wrote:
| My intuition matches yours. It's abundant enough to find its
| way into alloys for jet engine blades at single digit
| percentages:
| https://www.thenakedscientists.com/articles/science-features...
| And if used in chips, you don't need to make the full substrate
| with this material, just a few hundred nanometers at the top,
| in the active area.
| bob1029 wrote:
| The cost of the raw materials is a rounding error compared to
| all other aspects of semiconductor manufacturing.
|
| The entire industry is a game of "value-add". The blank silicon
| wafers start out with effectively zero (or negative) value. The
| raw materials are worthless to the business. Only once
| validated features (process layers) begin to accumulate do
| those raw materials begin to inherit some sense of value.
| lost_tourist wrote:
| Are you discounting the cost of development of technology to
| support the new semiconductor material? that along with it's
| rarity is what I suspect they're talking about.
| bell-cot wrote:
| A slightly important sentence, if you're caught up on the
| "...using Unobtainium" issue:
|
| > Although the new material is made using one of the rarest
| elements on Earth, the researchers suggest counterparts made from
| more abundant materials may be discovered that operate comparably
| fast.
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