e-beam litho just seems strange to me since electron beam 3D printing is just as fast as using lasers, so clearly the scanning part isn't the bottleneck. What is the bottleneck in this case?
Interesting. What sort of resolution is that 3D printing though?
> What is the bottleneck in this case?
My guess would be using a single beam? Perhaps it's possible to scale this up to multiple beams working on a die or wafer at a time time?
Which brings up another interesting question. Would this process require the same kind of wafer/substrate as traditional EUV machines? Perhaps using this approach opens up the possibility of using different materials that are easier, cheaper and faster to produce?
Dont't traditional kinds of wafers have to be grown and sliced from exotic/rare materials? If so the additional time to "etch" with this new process might be offset by other factors such as what goes in to preparing the wafer?
Around 50 microns I believe. Not at lithography resolutions obviously, but that's limited by metal powder grain size.
> My guess would be using a single beam?
Electron beams can scan a whole print bed very quickly to heat up the whole top layer [1] which can't be done using lasers. This can be done easily with electrons since they are deflected using magnetic coils, like good old CRT monitors, but this can't be done using lasers because they have to move the mirrors mechanically.
That's why it seemed weird that photolithography would be so much faster, but maybe it's as you say, lasers can be stacked for parallelism to make up for those downsides. Stacked electron beams might interfere with each other because you can't really isolate magnetic fields.
https://www.asml.com/-/media/asml/images/technology/43679-in...
[1] https://www.youtube.com/watch?v=en7hhFJBrAI around 7:30
Everything about this is crazy complex, and the state of the art in any given year is also secret to TSMC and other tiny-feature-size fabs.
But in addition to gradually upping the narrow-bandwidth/phase-coherent illumination frequency every year (which has many problems but continues to see continual progress), they've also long been using techniques to work around the diffraction limit/resolution barrier [1], such as subwavelength metamaterial "hyperlenses" / "superlenses" (previously widely thought to be impossible even in theory) [2][3] and "assist features" and other non-traditional masking elements to pre-compensate for imaging distortions [4]. Plus they fiddle a lot with the chip process to tune it in weird ways to assist with or compensate for the previous issues.
[1] https://en.wikipedia.org/wiki/Diffraction-limited_system
[2] https://en.wikipedia.org/wiki/Superlens#Theory
[3] "Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices" https://ieeexplore.ieee.org/document/8424820
[4] https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithograph...
The reality of how this is done is so much more complex than I would have thought: https://www.youtube.com/watch?v=f0gMdGrVteI Traditional techniques such as masks don't work when dealing with xrays.