3 ms·

Regarding this quote: > “The abstractions we worked so hard to maintain are becoming porous as secondary and tertiary effects bubble up through the whole flow

Regarding this quote: > “The abstractions we worked so hard to maintain are becoming porous as secondary and tertiary effects bubble up through the whole flow … from node to node, they intensify or change character,” he said, expressing optimism that “all of these effects will get solved.” Might you be able to provide a little more information about which effects are becoming problematic?

mechagodzilla 8y ago
A good example is 'multi-patterning.' With >16nm processes, a single mask layer had minimum pitch/width requirements you had to follow (i.e. wires must be at least this thick, and spaced at least this far apart). Now, multiple masks using horrendously complicated interference patterns are required to make the smallest layers (I think 7nm might use quad patterning, so 4 masks per layer at the finest pitch), so your mask costs just went up 4X, and your yield got worse. But that's not all! Now you need to think about which wires in that layer are part of which of the 4 masks (typically called the 'color' of the wires), so there are additional weird rules about the pitch between wires of a given color, all of which means it's just harder to design with, and it's harder to actually 'use' the increased density of the smaller features.
- canhascodez 8y ago
  And the purpose of this is to avoid quantum mechanical effects, correct? The "abstractions" being referred to are essentially being able to treat these things as if they are "wires" in the classical sense?
  - slededit 8y ago
    The purpose is to deal with the fact individual features are smaller than the wavelength of light used for the photo resist process. I'm not up to speed on the details of why we can't just use X-Rays but apparently its a difficult problem.
    - paulmd 8y ago
      Not an expert here but it's not trivial to generate the amount of energy needed at those frequencies, and you also need to generate enough photons (not just high-enough energy photons) that shot noise doesn't become a problem too.

mechagodzilla 8y ago

A good example is 'multi-patterning.' With >16nm processes, a single mask layer had minimum pitch/width requirements you had to follow (i.e. wires must be at least this thick, and spaced at least this far apart). Now, multiple masks using horrendously complicated interference patterns are required to make the smallest layers (I think 7nm might use quad patterning, so 4 masks per layer at the finest pitch), so your mask costs just went up 4X, and your yield got worse. But that's not all! Now you need to think about which wires in that layer are part of which of the 4 masks (typically called the 'color' of the wires), so there are additional weird rules about the pitch between wires of a given color, all of which means it's just harder to design with, and it's harder to actually 'use' the increased density of the smaller features.

canhascodez 8y ago
And the purpose of this is to avoid quantum mechanical effects, correct? The "abstractions" being referred to are essentially being able to treat these things as if they are "wires" in the classical sense?
- slededit 8y ago
  The purpose is to deal with the fact individual features are smaller than the wavelength of light used for the photo resist process. I'm not up to speed on the details of why we can't just use X-Rays but apparently its a difficult problem.
  - paulmd 8y ago
    Not an expert here but it's not trivial to generate the amount of energy needed at those frequencies, and you also need to generate enough photons (not just high-enough energy photons) that shot noise doesn't become a problem too.