3 ms·
> Once you get down to 5nm features they are only about 20 silicon atoms wide. This is a complete misunderstanding of modern processes. It’s conflating featur
by thechao 9y ago
> Once you get down to 5nm features they are only about 20 silicon atoms wide.
This is a complete misunderstanding of modern processes.
It’s conflating feature size with some measure like “wire width”. Feature size is best thought of as the tightest corner radius you can cut in a piece of wood. Actual logic (and wires) are far larger than this. There’s actually a shocking amount of room “down there”, still. The problem is that lithography probably won’t scale down after some magic number (say 2 or 3 nm), and we’ll have to do something else clever. It’s been a while since I looked into this, but IBM’s smallest AFM-created transistor is ~10 atoms, which is something like 4 orders of magnitude (or more!) smaller than, say, 10nm.
- eleitl 9y agoMoreover, the node numbers do no longer relate to any specific geometric feature, but are computed from how many standard (memory) cells fit a given area.
- notheguyouthink 9y agoReally ignorant question, but does size reduction affect heat dissipation at all?
- pjc50 9y agoSort of: thinner wires have higher resistance, so what tends to happen is you get slightly more heat but in a much smaller space. Heat dissipation has become a major limiting factor.
- tlb 9y agoYes. Most of the power goes into charging and discharging the capacitance inherent in each wire and transistor gate every time a signal changes. When you shrink by 2x, the capacitance goes down by about 4x (because it's proportional to area) and power goes down 4x also. (It's not exactly square-law, because the sides of wires have capacitance too, but at least at larger sizes it was close.) See https://en.wikipedia.org/wiki/Dennard_scaling https://en.wikipedia.org/wiki/Dennard_scaling for details.
- andars 9y agoCould you clarify the "4 orders of magnitude" comment? ~10 atoms is ballpark 2nm. If you are referring to a length dimension with your comment, four orders of magnitude larger would have some dimension on the order of 20um, corresponding to a 1970s process.
- Retric 9y agoHere is a 14 atom transistor aka 0.5nm, so they may be talking 10 total atoms: https://www.fanaticalfuturist.com/2017/09/researchers-use-just-14-atoms-to-build-the-worlds-first-0-5nm-transistor/ https://www.fanaticalfuturist.com/2017/09/researchers-use-ju...
- thechao 9y agoAlong those lines; yes. Current transistors are (effectively) hundreds of thousands, if not millions, of atoms.