Announcing and producing are two different things.
I believe this feature size has to do with the electrical channel and is not a physical feature. I'm wondering if the processing is truly continuing to advance with ever smaller features in proportion to this reference number? At some point the ever decreasing feature size will have to end since it is not practical to use X-rays in IC manufacturing. But then I'm not an IC designer, so maybe the will continue to come up with new tricks to make features ever smaller.
As far as I know, you are completely right. The "2nm" or "1nm" is related to the geometrical feature that would have an "equivalent" conventional device producing the expected extrapolated performances (speed, power consumption, leakage or whatever...). Just for comparison, bear in mind that the silicon lattice constant is about 0.5nm, so the
1nm channel is barely two silicon atomic layers. A device really sized at this scale should require a true technology breakthrough, where quantum or mesoscopic effects are not negligible.
The progress in manufacturing is mostly due to unconventional new structures (e.g. 3D fin fets) or brand new material or exhoteric semiconductor compounds. Indeed, a field of applied research that I am far for claiming trivial.
Classically the nodes were named by the minimum FET gate length. (You resize the device by changing the gate width, which is almost always much larger than the length.)
FinFETs started coming in at 32 nm iirc, in response to the creeping failure of Mead-Conway VLSI scaling. With VDD limited by gate length (a proxy for the width of the channel) and gate oxide thickness limited by leakage due to tunnelling, the only way to get enough E field to turn the FET on completely was to wrap the gate around three sides of the channel.
Since then processing has got hugely more complicated--instead of just silicon, oxygen, nitrogen, boron, phosphorus, aluminum, and copper, chips now contain most of the stable elements.
Ten years ago one of the major problems was huge variations in threshold voltage due to dopant atom statistics--it makes a lot of difference whether you have 90 or 100 dopant atoms in the channel, for instance. AIUI they solved that by atomic-layer deposition followed by local diffusion. Not your grandpa's quartz furnace anymore!
IBM has produced a larger proportion of all silicon processing technology than any other organization. I haven't been there for a dozen years now, but I'm glad to see that that part of the IBM legacy continues.
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