I am wondering if I read this correctly:
To reach such tiny geometries, self-aligned quadruple patterning (SAQR) and EUV lithography is used.
So they are using EUV which supposedly has long exposure times due to output power problems from the light source through the mask to the wafer, and they are quad-patterning it? Are they using the term "quad-patterning" to mean that they are using four different masks for each layer and then exposing each one? With a 13nm light source why do they need to quad-pattern a 7nm feature size? And how long would that actually take in a real fab? Everyone is moaning about double-patterning using a 193nm light source on 20nm and smaller and the effect on throughput (and thus on cost). I thought one of the wonderful things about EUV was that you could get rid of double-patterning, but if this article is to be believed (and I'm reading it correctly) they are actually taking a much slower lithography patterning machine (EUV) and then using four masks per layer... which seems like it would take so long that it never be commercially viable... and I'm not sure that I understand why you even need to do anything this complex.
Anyway, it's interesting.... it just seems perplexingly complex and extremely far from commercialization in a high volume fab that needs higher wafer throughput to maintain cost effectiveness.
As always, I am not speaking on behalf of my employer, and my opinions are my own.
As background reading, this link talks about the problems of exposure times on EUV:
http://spectrum.ieee.org/semiconductors/devices/euv-chipmaking-inches-forward
and this one talks about the talks about the way node sizes are named - something that IDC has been talking about for years but I only finally understood what he was saying fairly recently - and problems at 14nm and below:
http://spectrum.ieee.org/semiconductors/devices/the-status-of-moores-law-its-complicated
And by the way, while I'm posting up about EUV, I would just like to point out that the way that the light source is made - by dropping molten tin into a high power laser beam which vaporizes the tin and creates 13.5nm ultraviolet light seems completely crazy to me. I understand that this is where the industry is headed, but as a source of light dropping molten metal into a laser beam while you have a jet of hydrogen gas to steer the drops seems completely Rube-Goldbergian to me. It might be practical, it might be necessary, but it still seems like "you have to be kidding me... really? that's the way it works?".