
Is 7nm the Last Major Node? - SemiTom
https://semiengineering.com/7nm-last-major-node/
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_nalply
I wondered how 7nm compares to the size of single silicon atoms. Google says
the van der Waals radius of a silicon atom is 210pm. This translates to around
30 atoms for 7nm, considering about 20% spacing between atoms. However I am
not a chemist, so perhaps I am wildly off. Anyone here can give some
elucidation?

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qubex
If I am not mistaken, a 14nm feature is about 20 or so Si atoms wide, so a 7nm
feature would be about 10 or so Si atoms wide. If this is correct, clearly the
next process node after 7nm (3.5nm, presuming halving each time) would be the
last process node that allows an integer breadth (5 Si atoms). Beyond that
you'd be down to non-integer feature breadths (or alternatively, non-integer
average breadths with wide variances).

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ksec
In terms of TSMC Roadmap, We have

10nm > 2017 7nm > 2018 7nm+ > 2019 7nm EUV / 5nm > 2020

Is the same thing they said 16nm was the last major node, but TSMC, after 4 -
5 iteration of 16nm, with one of them now called 12nm, has gotten cheaper. And
it seems they have plans to further reduce the cost of 16/12nm.

I expect the same for 7nm. Both 12nm and 7nm will be much more affordable in
2020. Right now the uncertainty is 5nm and 3nm. Both are technically
achievable, the problem is cost. At the moment 5nm+ cost structure looks like
exclusive to certain industry and clients. Unless they bring in 450mm wafer
but i have no idea how that is working out.

And 28nm remains the cheap and cherrful solution with no replacement in sight.

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mrep
Is 28nm still the cheapest when lifetime power consumption is factored into
the cost?

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ksec
Cheapest in terms of Design and Manufacture at Scale. As a matter of fact 28nm
prices is going up due to supply constraint, and 22nm ULP is not out and wont
be as cost effective yet, and i doubt it will be in the future, it will be a
tool for TSMC to keep higher margin.

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gbrown_
Probably.

