[alted]

Judging from [1], Sam Zeloof's plan might include using electron beam lithography, which scans an electron beam over a wafer surface, instead of normal photolithography. This can get high resolution (10nm) comparable with EUV, and could theoretically be built out of a hacked scanning electron microscope. Photolithography is the step that limits fabrication size, so e-beam litho allows cheap transistors comparable with state-of-the-art.

The main problem is e-beam litho is extremely slow. It might take ~1 day to do a single photolithography step for a 1x1cm chip, whereas an EUV machine can pattern a 300mm diameter silicon wafer in < 1 minute. (The next problem is making everything reliable. Billions of transistors (a modern CPU) needs a failure rate per transistor of better than 1e-9.)

Maybe that's enough for extremely-low-volume production?

[1] https://mobile.twitter.com/szeloof/status/154993704406717235...

[consp]

Mapper[1] did this, tried to commercialize it and went bankrupt in 2018 and ASML scooped up the remains[2].

[1] https://nl.wikipedia.org/wiki/Mapper_Lithography (no English page available)

[2] https://www.asml.com/en/news/press-releases/2019/asml-agrees...

[lysozyme]

Doesn’t necessarily make it a bad idea to try again. It seems that photolithography as a process is stretched to its limits. Easy to see the diminishing returns. The electron beam lithography is a different kind of process. It seems like it’s precise enough, just slow. That sounds like good news to me. “Make it go faster” is something we typically can achieve.

[sanxiyn]

> ... electron beam lithography ... could theoretically be built out of a hacked scanning electron microscope

Not only theoretically. Sam hacked his own scanning electron microscope and did electron beam lithography in 2018.

http://sam.zeloof.xyz/e-beam-lithography/

[bippingchip]

e-beam litho is anything but fast though: the machines are cheaper but they are much much slower in wafer throughput than the insanely expensive ASML EUV machines.

Now the website claims a fast fab, but leaves it open what that means: fast production of wafers? Or slow production of wafers that run fast?

[pclmulqdq]

There are some theoretical approaches that you could use to make e-beam a lot faster, and I'm not sure anyone has really explored them due to the unreasonable effectiveness of photolithography. Basically, SEMs and e-beam machines today use a low- or medium-power electron beam that they treat as a static beam, and scan slowly to keep the "static" assumption. If you instead think if it as a traveling particle stream, you may be able to "pipeline" the process of steering the beam as it travels down the microscope, allowing you to crank up the power and run the process a lot more quickly. It would be very cool to see a startup pursue super-fast e-beam and make it work, and it's a niche I'm excited to see explored.

[alted]

A common approach is to use multiple electron beams in parallel ([1] is up to 262144 beams!). This is starting to be used commercially to create the masks for photolithography.

[1] https://www.ims.co.at/en/products/

[frognumber]

Personally, I think there is an undertapped market for extremely low volume productions. The cost of a mask set is in the hundreds of thousands of dollars, and there is very little custom or domain-specific IC design.

I do think it's a slow market to emerge. They'd need very patient funding. If nothing else, tooling needs to catch up, which is 5+ years.

[paulmd]

apart from massively-parallel beam systems as discussed elsewhere here, it seems more likely to me that e-beams could be used for mask-making, which might make it easier for smaller clients to make the jump to modern processes.

like if you can do a 7nm or 14nm tier mask maybe that becomes a pivot to a 28nm actual production process, or maybe it makes multipatterning and some of the other advanced-node tricks more accessible at a semi-reasonable cost.

[amluto]

I wonder if e-beam lithography would make registration easier. With photolithography, I assume one must position the wafer relative to the mask extremely precisely. With e-beam lithography, the tool is a scanning electron microscope, and as long as the wafer doesn’t move, the software could potentially locate it to essentially arbitrarily high precision and then offset and rotate the scanning pattern accordingly.

ASML surely charges plenty for their alignment hardware:

https://www.asml.com/en/news/stories/2021/fellow-simon-mathi...

[ip26]

From the description of a “fast fab” and this, perhaps the play is to beat photolithogaphic fans on turnaround, e.g. GDS-to-first-silicon latency. An e-beam doesn’t need masks made.

[bee_rider]

I was under the impression that electron beam could fundamentally get much smaller than light (electrons are “smaller” than photons in some funky physics sense), but was just really slow.

Also (fuzzy memories of semiconductor classes, but) the size doesn’t tell the whole story, right? With photons I’m under the impression that the wavelength of the light is much higher than the feature size, so they have to do funky things with the masks to make it all work out. Playing with interference or whatever. (Someone who knows more about this can feel free to embarrass me, I’m sure it will be educational!)

Electrons are relatively speaking more like the nice little billiards ball thwacking away at the SI that we like to imagine.

[hajile]

> Electrons are relatively speaking more like the nice little billiards ball thwacking away at the SI that we like to imagine.

They are as long as you keep a close eye on them…

[Animats]

> The main problem is e-beam litho is extremely slow.

There are now some multi-beam systems.[1]

[1] https://multibeamcorp.com/products/

[moring]

1 day for (1cm)^2 is 15 minutes for (1mm)^2. That might be okay for a start -- I suppose they do not want to go for the largest chips right from the beginning.

[jjk166]

At the N5 node 1mm^2 of a fully finished wafer is worth about 25 cents. This may have undergone hundreds of steps. If we assume the chips we're making can be done in 100 steps, one of these E-Beam Lithography machines costs the same amount as a scanning electron microscope, can run 24/7 for years, and there are zero costs to operate, and we need to break even in 2 years, then we need to charge about 450 times as much as a mass produced chip. Obviously under more realistic conditions, that multiplier would have to be way higher.

While for steady state production, a chip could be produced every couple of hours, no one is going to pay tens of thousands per chip for even a limited production run. If you are doing a one off prototype that justifies an extremely high pricetag, you have long lead times waiting for the chip to go through the various steps.

Honestly you'd be better off just making custom masks.

[BirAdam]

E-beam is mentioned in their hiring verbiage:

> We believe our team and lab can build anything. We’ve set up 3D printers, a wide array of microscopes, e-beam writers, general fabrication equipment - and whatever is missing, we’ll just invent along the way.