mjshackl,The Stanford architecture looks like the one used by...

mjshackl,

The Stanford architecture looks like the one used by Crossbar for its Tbt chip.

There is a selector line under many layers of cells ("Selector line").

I think it means that the selector selects several cells at the same time.

Toshiba does the same with its adavanced NVM (NVM Express). They select a block of cells at the same time. The block is smaller than with Nand were you have to erase a 20 Mbt block and rewrite it just to change one cell from 0 to 1.

I suspect that it's why they doesn't seem to have any success.
You have to sacrifice too much speed doing that even if you have to erase only an 8 cells block.

And, more importantly, you can't adress one cell individualy like DRAM.
If the memory is to emulate DRAM it needs to have the same adress system, imo.

But this is only what a layman can conclude. No scientific or technical basis.


Also, I want to correct what I said yesterday : That you need EUV to make a vertical ReRam array.
This is obviously not true because WDC, Kioxia and Micron are making 3D NAND with pillars through the layers, without using EUV.

In fact I was quoting a Crossbar engineer.
Obviously Croassbar tried to make a 3D NAND like vertical staking with its filamentary ReRam cells, and failed.

The Micron boss also said that they will only start to use EUV when they will developp their ReRam memory in 2024.
So, it seems that this is a shared opinion in the industry : No low cost ReRam without EUV.

But maybe it's only for very small geometries.

If 4DS decided to stay around 40 nm, wich is the average cell size in 3D NAND, 4DS could probably use the technology used today by WDC or Micron .
In fact it seems that 3D NAND cell size ar bigger than recent planar 2D NAND.
I think they choose a larger cell size to allow more bits per cell, but also because the vertical pilar could be larger and easier to make.

The more I look at it, the more I think they had a working array last year, but decided to go for a smaller geometry.
Then they had a problem.


Just my thoughts