“Everyone knows that flash memory is about to hit its scaling limit – it’s right around the corner.”
And then he backs off a bit:
“One thing that is quite clear is that nobody knows when NAND flash will stop scaling. Everyone knows that it’s soon, but researchers continue to find ways to push the technology another couple of process nodes past where anyone thought it could possibly go, and they have been doing this since the early part of this century.”
This statement reflects my perspective exactly. It’s not as though things are going in the right direction as Flash scales. Well, some things actually are going in the right direction: cell size and cost/bit for example. But characteristics such as endurance, retention time, and error rate are not getting better. They’re getting worse with each new NAND Flash generation. We compensate for these increasingly troublesome failings with more and better error correction and managed Flash arrays that allow us to defy the ravages of scaling.
Because of these issues, researchers working on alternative non-volatile memory technologies smell blood in the water. They cast a hungry eye on the huge and growing sales volumes in the NAND Flash business and repeatedly try to dethrone the king. (Take a look at “SK Hynix places bet on third wannabe non-volatile memory technology, phase-change memory, with IBM.”)
Handy writes about this aspect too:
“If NAND flash continues to defy scaling limits then any successor technology has that much more time to become understood. This also gives new, unheard-of technologies an opportunity to rise to displace those technologies that today appear to have the best chance of succeeding NAND flash.
This means that even the strongest candidate today cannot be guaranteed to be in the best position once flash finally stops scaling. In other words: Nobody knows what will replace NAND flash. It could be any of today’s contenders: PCM, MRAM, FRAM, or even RRAM, or it could be some technology that has not yet produced prototypes like carbon nanotubes or some organic compound.”
But that time might not come for a while. For example, NAND Flash vendors have been candid about looking towards monolithic 3D IC structures for future Flash memory cells. (See “3D Thursday: A look at some genuine 3D NAND cells, courtesy of Micron” from last year’s Flash Memory Summit for example. By the way, this year’s Flash Memory Summit is just around the corner. Sign up here.)
Finally, Handy rightly points out that the transition from NAND Flash memory to who-knows-what memory as a successor will also have some affect on the SSD controller vendors, which have been very much in the news lately. (See “SK Hynix to acquire SSD controller vendor Link_A_Media for $248 million. That makes four.”)
Here, Handy writes:
“Perhaps the most profound impact will be felt by designers of SSD controllers. These people, absolute geniuses to my understanding, have finely-tuned repertoires and a deep understanding of how to hide all the foibles of NAND flash: Error correction, write acceleration, wear leveling, background garbage collection, etc. All of these fine techniques are likely to suddenly become altogether unnecessary, and these highly-qualified specialists will suddenly find themselves out of a job.”
Well, perhaps not. I don’t think that any future memory cell, no matter the underlying technology, is likely to be an error-free media. (Wouldn’t it be great if that did happen? However, I haven’t seen one yet.) What’s likely to happen in my opinion that that any new non-volatile memory technology that manages to supplant NAND Flash memory will have its foibles and will require some of the same data-reliability countermeasures—which we use for turning less-than-perfect NAND Flash memory arrays into reliable data storage—and some new ones as well. In that case, those highly qualified controller specialists (and the associated IP providers) will find themselves in even greater demand.