3 ms·

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!
      - voldacar 4y ago
        Read up on the Zeiss optics that go into the ASML EUV machines. (or at least what is publicly available knowledge). It's truly insane
  - deleted 4y ago
    [deleted]
  - Tuna-Fish 4y ago
    They go pretty hardcore on the optics. Have a look at their light path: https://www.asml.com/-/media/asml/images/technology/43679-inside-nxe3400.jpg?mw=1200&rev=117e2fba11004fc7a59362167df27a8a&hash=3B700AAB58CEB68BF0FB956073BEFC37 https://www.asml.com/-/media/asml/images/technology/43679-in...
  - kosievdmerwe 4y ago
    One youtube video[1] I watched had someone state that if you scaled up one of the curved mirrors to the size of the Earth, the largest imperfection would be the width of a hair. [1] https://www.youtube.com/watch?v=en7hhFJBrAI https://www.youtube.com/watch?v=en7hhFJBrAI around 7:30
DougMerritt 4y ago
> Crazy they have physical masks with features as small as 7nm. 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 https://en.wikipedia.org/wiki/Diffraction-limited_system [2] https://en.wikipedia.org/wiki/Superlens#Theory https://en.wikipedia.org/wiki/Superlens#Theory [3] "Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices" https://ieeexplore.ieee.org/document/8424820 https://ieeexplore.ieee.org/document/8424820 [4] https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithography#Enhancement_opportunities_for_EUV_patterning https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithograph...

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!
    - voldacar 4y ago
      Read up on the Zeiss optics that go into the ASML EUV machines. (or at least what is publicly available knowledge). It's truly insane
- deleted 4y ago
  [deleted]
- Tuna-Fish 4y ago
  They go pretty hardcore on the optics. Have a look at their light path: https://www.asml.com/-/media/asml/images/technology/43679-inside-nxe3400.jpg?mw=1200&rev=117e2fba11004fc7a59362167df27a8a&hash=3B700AAB58CEB68BF0FB956073BEFC37 https://www.asml.com/-/media/asml/images/technology/43679-in...
- kosievdmerwe 4y ago
  One youtube video[1] I watched had someone state that if you scaled up one of the curved mirrors to the size of the Earth, the largest imperfection would be the width of a hair. [1] https://www.youtube.com/watch?v=en7hhFJBrAI https://www.youtube.com/watch?v=en7hhFJBrAI around 7:30

DougMerritt 4y ago

> Crazy they have physical masks with features as small as 7nm. 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 https://en.wikipedia.org/wiki/Diffraction-limited_system [2] https://en.wikipedia.org/wiki/Superlens#Theory https://en.wikipedia.org/wiki/Superlens#Theory [3] "Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices" https://ieeexplore.ieee.org/document/8424820 https://ieeexplore.ieee.org/document/8424820 [4] https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithography#Enhancement_opportunities_for_EUV_patterning https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithograph...