EUV being the biggest suspect for yield boost. The 6nm EUV, and 7nm EUV were niche processes incompatible with non-EUV versions, and had own special design rules. I believe very few companies went for them other than for trial runs to gather expertise.
TSMC 5nm uses EUV by default, and very likely has no quad patterning layers, and possibly they threw out double patterning layers too.
Not having to give any considerations to multiple patterning should allow for much freer design rules, and let recover density from sacrificial lines.
“Part of what makes 5nm yield slightly better is perhaps down to the increasing use of Extreme UltraViolet (EUV) technology, which reduces the total number of manufacturing steps. Each step is a potential chance to decrease yield, so by replacing 4 steps of DUV for 1 step of EUV, it eliminates some of that defect rate.”
Yes, and I believe TSMC does. Because the dose scales as resolution to the 4th power (or so), it is better to double pattern than to try to single pattern at massive dose. There are also cases where double patterning can reduce defects in self aligned schemes.
TSMC 5nm uses EUV by default, and very likely has no quad patterning layers, and possibly they threw out double patterning layers too.
Not having to give any considerations to multiple patterning should allow for much freer design rules, and let recover density from sacrificial lines.