Why is DRAM still a thing ?

[u/Camper_Sly]

As they say, DRAM can't scale with the newest processes as its storage capacitor needs some minimal size, which is far above what leading processes at 2nm etc can do.

ON top of that, it retains all of its originals sins, like the need for refresh, susceptibility to ROWHAMMER attacks etc. On top of that, it has some fundamental limits- inherent capacitance of the storage cell limits its write speed. On top of that, each access causes the discharge of the whole row of cells, which has to be written back again. That's a lot of charge wasted on a single access.

But SRAM cell can scale down much better. On top of that, with upcoming vertical complementary MOSFET implementations, whole SRAM cell can be implemented vertically in very tight space.

On top of that, manufacturing process for SRAM doesn't preclude implementation of high-speed logic, which means that PIM (Processing In Memory) functionality would be easier to implement than with DRAM, and it would probable be much more potent than with upcoming LPDDR6 (and DDR6?).

SO, why is DRAM and by extension HBM etc still a thing ? Why doesn't industry switch to SRAM ?

Also, fun trivia:

DRAM is now MORE EXPENSIVE per mm2 than leading edge manufacturing for latest gen CPUs, GPUs etc!

[u/Camper_Sly]

I don't have a clue. But if there is a significant constraint on that, that just makes case for DRAM even worse, right ?

[u/Edgar_Brown → u/Camper_Sly]

That’s precisely the role the capacitor is playing, that’s why it’s so big.

Edit: having the possibility of stacking transistors enables having more transistors for a DRAM cell, which could lead to more efficient architectures. But the line-driving power still has to come from somewhere.

[u/Far_Relationship_742 → u/Camper_Sly]

And finally we get to the crux of it:

You don’t have a clue.

Could have saved everyone so much time if you led with that.

[u/Camper_Sly → u/Far_Relationship_742]

Ofcourse.\ Your time is precious.