SRAM has really stalled. I don’t think 5nm was much better than 7nm. On ever smaller nodes, sram will be taking up a larger and larger percent of the entire chip. But the cost is much higher on the smaller nodes even if the performance is not better.
I can see why AMD started putting the SRAM on top.
Re:Apple introduces M4 chip
by magicalhippo on Tuesday May 07, 2024 @01:39PM
(#40288955)
It wasn't immediately clear to me why SRAM wouldn't scale like logic. This[1] article and this[2] paper sheds some light.
From what I can gather the key aspects are that decreased feature sizes lead to more variability between transistors, but also to less margin between on-state and off-state. Thus a kind of double-whammy. In logic circuits you're constantly overwriting with new values regardless of what was already there, so they're not as sensitive to this, while the entire point of a memory circuit is to reliably keep values around.
Alternate transistor designs such as FinFET, Gate-all-around and such can provide mitigation of some of this, say by reducing transistor-to-transistor variability by a factor, but can't get around root issue.
[1]: https://semiengineering.com/sram-scaling-issues-and-what-com...
[1] https://semiwiki.com/semiconductor-manufacturers/tsmc/322688...
[2] https://semiengineering.com/sram-scaling-issues-and-what-com...
[3] https://semiengineering.com/sram-in-ai-the-future-of-memory/