[happytiger]

> “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]

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...

[jiggawatts]

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]

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]

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?

[seszett]

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.

[runeks]

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.

[chmod775]

> 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.

[mhb]

And when the price of something goes up, it is more rewarding to find and process more of it.

[lazide]

At a million/kg, new methods of production would definitely be found. Even if it was some kind of neutron bombardment element synthesis.

[runeks]

> 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-rhenium.pd...

[adrian_b]

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.

[bpye]

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]

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]

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.

[tuyiown]

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.

[maeln]

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.

[Almondsetat]

The rarest or rare material can still be used in extremely specialized applications though