3 ms·

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 i

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?

chrisjc 4y ago
> since electron beam 3D printing is just as fast as using lasers 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?
- naasking 4y ago
  > Interesting. What sort of resolution is that 3D printing though? 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. [1] https://www.youtube.com/watch?v=jqjD-FWMexo https://www.youtube.com/watch?v=jqjD-FWMexo
  - amluto 4y ago
    Photolithography fabs don’t use scanning lasers — they shine light through a mask and expose a large area at once.
    - naasking 4y ago
      Crazy they have physical masks with features as small as 7nm. I assume those are movable somehow but that seems like incredibly delicate work.
      - kosievdmerwe 4y ago
        You can use lenses and curved mirrors to make a larger mask focus the light onto a smaller area.
        naasking 4y ago
        That still seems pretty delicate. The lenses and mirrors would have to be aberration-free to an extreme degree so as to not introduce too many artifacts, and moving the mask further from the surface would increase risk of diffraction artifacts, no?
        haneefmubarak 4y ago
        It is, but that's how modern semiconductor lithography is done. Massive lenses and mirrors (both made of different materials that normal, since they need to have optical properties at wavelengths much smaller than human vision) are manufactured at great cost to ensure that it is free of aberrations. The extremely limited supply of these is actually one of the many factors that restricts the ability to move to newer processes and scale production capability of newer lithographies.
        naasking 4y ago
        For good telescope optics, we look for something like 1/4 - 1/6 wavelength tolerance, minimum. That's for optical wavelengths, but photolithography is in the UV range, so that's already stricter tolerance in absolute terms because of the shorter wavelength, but how does the tolerance in relative terms compare? Thanks for the info!
thinkyfish 4y ago
EUV can expose a whole chip image in a single shot. Raster scanning electrons takes about 4 hours to do the same image.
ThePhysicist 4y ago
You need to deposit a specific amount of energy into your resin to polymerize it, that takes time as you can't just crank up the amount of charge or the energy / electron in your e-beam as that will usually increase the energy variance and thereby the aberration. It's much easier to produce a coherent beam of light with sufficient energy than a coherent beam of electrons with comparable energy.
jjk166 4y ago
No the scanning is the bottleneck, scanning laser photolithography is equally slow. For mass production of chips, photolithography is done with a light source that illuminates a "large" area all at once.

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?

chrisjc 4y ago

> since electron beam 3D printing is just as fast as using lasers 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?

naasking 4y ago
> Interesting. What sort of resolution is that 3D printing though? 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. [1] https://www.youtube.com/watch?v=jqjD-FWMexo https://www.youtube.com/watch?v=jqjD-FWMexo
- amluto 4y ago
  Photolithography fabs don’t use scanning lasers — they shine light through a mask and expose a large area at once.
  - naasking 4y ago
    Crazy they have physical masks with features as small as 7nm. I assume those are movable somehow but that seems like incredibly delicate work.
    - kosievdmerwe 4y ago
      You can use lenses and curved mirrors to make a larger mask focus the light onto a smaller area.
      - naasking 4y ago
        That still seems pretty delicate. The lenses and mirrors would have to be aberration-free to an extreme degree so as to not introduce too many artifacts, and moving the mask further from the surface would increase risk of diffraction artifacts, no?
        haneefmubarak 4y ago
        It is, but that's how modern semiconductor lithography is done. Massive lenses and mirrors (both made of different materials that normal, since they need to have optical properties at wavelengths much smaller than human vision) are manufactured at great cost to ensure that it is free of aberrations. The extremely limited supply of these is actually one of the many factors that restricts the ability to move to newer processes and scale production capability of newer lithographies.
        naasking 4y ago
        For good telescope optics, we look for something like 1/4 - 1/6 wavelength tolerance, minimum. That's for optical wavelengths, but photolithography is in the UV range, so that's already stricter tolerance in absolute terms because of the shorter wavelength, but how does the tolerance in relative terms compare? Thanks for the info!

thinkyfish 4y ago

EUV can expose a whole chip image in a single shot. Raster scanning electrons takes about 4 hours to do the same image.

ThePhysicist 4y ago

You need to deposit a specific amount of energy into your resin to polymerize it, that takes time as you can't just crank up the amount of charge or the energy / electron in your e-beam as that will usually increase the energy variance and thereby the aberration. It's much easier to produce a coherent beam of light with sufficient energy than a coherent beam of electrons with comparable energy.

jjk166 4y ago

No the scanning is the bottleneck, scanning laser photolithography is equally slow. For mass production of chips, photolithography is done with a light source that illuminates a "large" area all at once.