3 ms·

No. The feature size is 7nm. That's like saying the tightest radius in your CNC mill's tooling is 3mm. The stuff you make is far larger. Just look at the SRAM

No. The feature size is 7nm. That's like saying the tightest radius in your CNC mill's tooling is 3mm. The stuff you make is far larger. Just look at the SRAM area: it's .0269 square microns. And SRAMs are tiny compared to "gate" RAMs, like you'd see in a book.

joezydeco 9y ago
The first line in that slide still blows me away. 17 million gates per square millimeter.
- thechao 9y ago
  Yeah. I'm gonna attempt a Fermi analysis to try give an idea of how much room is still "down there". 1 sq um is 100,000,000 sq angstroms. The unit cell of crystalline SI is probably around 50 sq A. That gives about 2,000,000 unit cells per sq micron. My guess would be about 5,000,000 "surface" atoms. The SRAM is .025 of that---perhaps 120000 atoms. SRAMs are cubes, so about 40,000,000 atoms cubically. Assume an SRAM is about the size of 8 transistors (that's a big SRAM): that's about 5,000,000 atoms per transistor. I'm going to fudge it down to 500,000 atoms, to be conservative. The smallest logic I've heard of is a transistor using 7 atoms in toto. That is a factor of 70,000x, or about 16 generations. Now, how we'll get there, I don't know. Also, I think the generation gap will probably widen to 5, or more, years. So... 75 to 100 years of "room"?
  - xenadu02 9y ago
    My understanding is that the active gate region is far smaller already so there is less room to scale than you might think.
    - thechao 9y ago
      The active region is smaller, but this is an argument about total bulk. IBM has shown functioning transistors with only a handful of atoms, already.
      - xenadu02 9y ago
        Yes, but that's the limit. Quantum effects mean we'll probably never see a single-atom transistor. Even if we did that's only a few more scalings. The rest of the features won't shrink as much anyway. We can see the end of the road. AFAIK no one has any clue how to even start thinking about 2nm or beyond. No one is even certain we will hit 5nm.
  - yborg 9y ago
    At what point does stray ionizing radiation make devices too error-prone to be useful I wonder?

joezydeco 9y ago

The first line in that slide still blows me away. 17 million gates per square millimeter.

thechao 9y ago
Yeah. I'm gonna attempt a Fermi analysis to try give an idea of how much room is still "down there". 1 sq um is 100,000,000 sq angstroms. The unit cell of crystalline SI is probably around 50 sq A. That gives about 2,000,000 unit cells per sq micron. My guess would be about 5,000,000 "surface" atoms. The SRAM is .025 of that---perhaps 120000 atoms. SRAMs are cubes, so about 40,000,000 atoms cubically. Assume an SRAM is about the size of 8 transistors (that's a big SRAM): that's about 5,000,000 atoms per transistor. I'm going to fudge it down to 500,000 atoms, to be conservative. The smallest logic I've heard of is a transistor using 7 atoms in toto. That is a factor of 70,000x, or about 16 generations. Now, how we'll get there, I don't know. Also, I think the generation gap will probably widen to 5, or more, years. So... 75 to 100 years of "room"?
- xenadu02 9y ago
  My understanding is that the active gate region is far smaller already so there is less room to scale than you might think.
  - thechao 9y ago
    The active region is smaller, but this is an argument about total bulk. IBM has shown functioning transistors with only a handful of atoms, already.
    - xenadu02 9y ago
      Yes, but that's the limit. Quantum effects mean we'll probably never see a single-atom transistor. Even if we did that's only a few more scalings. The rest of the features won't shrink as much anyway. We can see the end of the road. AFAIK no one has any clue how to even start thinking about 2nm or beyond. No one is even certain we will hit 5nm.
- yborg 9y ago
  At what point does stray ionizing radiation make devices too error-prone to be useful I wonder?