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by weatherlight
1711 days ago
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First though, "5nm", "3nm" and so on are just marketing names. There is nothing about "5nm" that makes it "5nm" other than the company in question saying it is. Some things are smaller than 5nm on a given 5nm node, and some are larger. I cannot recall exactly what node this started to be the case (there used to be an actual definition, one for DRAM, one for logic), but it was in the past two decades and got particularly ridiculous beginning around "28nm" up to now.
The really concerning physical dimension for quantum tunneling to occur/not occur is "gate length," and that's been basically sitting around ~16nm (actual, real, literal 16nm), plus or minus a few nanometers (depending on the manufacturer and process in question), since about "45nm" (mid-late 2000s). So that one critical dimension isn't getting smaller. And there isn't much they can do about it right now.
They are still shrinking other dimensions though, and things don't work like they used to. Powered off transistors aren't really off, and leak power.
The workaround for this is that they just use bigger transistors in certain places for what's called "power gating". You get the benefits of having tons of small transistors, with a slight area penalty.
In addition to power gating, they have made substantial improvements to the design of the transistors themselves. Gates now wrap around the channel on 3 sides, creating a device known as a Finfet. Silicon dioxide is no longer used as an insulator to the same extent -- hafnium dioxide preforms much better as an insulator. Gates are now metal instead of polysilicon. And there's an assortment of other changes that have occurred or are on the way. So performance has actually managed to improve somewhat, and things have still gotten smaller. The end is near... but not quite yet.
Gate length is not going to budge much unless some miracle occurs, though. |
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I wonder if that is some kind of cultural shift that is taking place that started around 2009, or if it's always been like this and I just never noticed.
BMW model numbers used to more or less accurately reflect engine sizes, not anymore, it's just numbers now.
2G, 3G, 4G used to mean something, not anymore.
I could add a remark about the federal reserve, but... I'll just stay away from that. Don't want to be too edgy/turn this into a political discussion (I just think it's interesting from a cultural perspective).
It's like we collectively decided that "it's just numbers, man."