One layman question here maybe someone with better knowledge of the field can answer: could it make sense at some point to work without masks and lights and have only large scale laser arrays that write the structures directly but in the smallest possible scale (electrons)? Wouldn’t such an array be more energy efficient, be able to acquire smaller scales and trough the parallel process at some point be as fast as current systems using masks + light?
This is called electron beam writing, and is done routinely in research settings and to write the lithography masks, but does usually not have the required throughput for a production line. The upside of mask-based lithography is that all structures are exposed at once.
A single beam column with the machine around it costs millions already, and takes quite some space. Wafers are simply not large enough to accommodate more than, I'd guess, two or three columns at the same time. Each with independent optics.
A somewhat simple 2x2 cm Si photonics Chip in my line of work takes about 24h exposure for two layers - a full scale wafer is hundreds of times larger, more complex, and has dozens of layers. The math, physics, and geometry just don't really work out (yet)
You would think you can make the lithography faster with electron beams by just having many beams in parallel. But as far as I understand that’s doesn’t really work if you try to have too many beams: keep in mind that the electron beams would be extremely negatively charged. So they’ll repell each other if they get too close.
