XFEL is going to be destructive to the chip. It can't be the future.

> However EVs and green-tech are analagous to the XFEL path, they built from scratch and leapt over the competition that was happy to sit on it's existing profitable tech instead.

I'm not convinced Chinese EVs are technologically better. They've just command economied demand and reduced costs via mass production. The technology seems pretty inline with anything available in the West but demand isn't there to take advantage of scale. China is ahead in EVs by metric of quantity for sure but I don't think they're got next gen battery tech they are keeping secret.

This is a totally different technology.

A free electron laser (FEL) uses free electrons (electrons not attached to a nucleus) as a lasing medium to produce light. The light would shine through a mask and expose photoresist more or less just like the light from ASML’s tin plasma contraption, minus the tin plasma. FELs, in principle, can produce light over a very wide range of wavelengths, including EUV and even shorter.

That DARPA thing is a maskless electron beam lithography system: the photoresist is exposed by hitting it directly with electrons.

Electrons have lots of advantages: they have mass, so much less kinetic energy is needed to achieve short wavelengths. They have charge, so they can be accelerated electrically and they can be steered electrically or magnetically. And there are quite a few maskless designs, which saves the enormous expense of producing a mask. (And maskless lithography would let a factory make chips that are different in different wafers, which no one currently does. And you need a maskless technique to make masks in the first place.) There were direct-write electron-beam research fabs, making actual chips, with resolution comparable to or better than the current generation of ASML gear, 20-30 years ago, built at costs that were accessible to research universities.

But electrons have a huge, enormous disadvantage: because they are charged, they repel each other. So a bright electron beam naturally spreads out, and multiple parallel beams will deflect each other. And electrons will get stuck in electrically nonconductive photoresists, causing the photoresist to (hopefully temporarily) build up a surface charge, interfering with future electron beams.

All of that causes e-beam lithography to be slow. Which is why those research fabs from the nineties weren’t mass-producing supercomputers.

What bandwidth limitations are you referencing? My understanding is that deep euv lithography is limited by chromatic aberration, so the narrow bandwidth of a single beam FEL would be an advantage. If you need more bandwidth, you can chirp it. Is the bandwidth too high?

Oh, that’s neat. It uses high-harmonic generation.

My sole personal experience with any sort of harmonic generation was being in the room while some grad students debugged a 266nm laser that consisted of a boring 1064nm Nd:YAG laser followed by two frequency doublers. Quite a lot of power was lost in each stage, and the results of accidentally letting the full 1064nm source power loose were mildly spectacular.

I wish Lumiverse luck getting any appreciable amount of power out of their system. (FELs, in contrast, seem to be cable of monstrous power output — that’s never been the problem AFAIK.)

P.S. never buy a 532nm laser from a non-reputable source. While it’s impressive that frequency doubled Nd:YAG lasers are small and cheap enough to be sold as laser pointers these days, it’s far too easy for highly dangerous amounts of invisible 1064nm radiation to leak out, whether by carelessness or malice. I have a little disreputable ~510nm laser pointer, which I chose because, while I don’t trust the specs at all, 510nm is likely produced directly using a somewhat unusual solid state source, and it can’t be produced at all using a doubled Nd:YAH laser. The color is different enough that I’m confident they’re not lying about the wavelength.