"Self-Healing" NAND Flash Memory That Can Survive Over 100 Million Cycles
another random user writes with an interesting use of 800C heating elements to keep flash working longer. It's long been known that heating NAND to temperatures around 250C can restore life, but doing so was practically impossible. From the article: "Engineers at Macronix have a solution that moves flash memory over to a new life. ... They redesigned a flash memory chip to include onboard heaters to anneal small groups of memory cells. Applying a brief jolt of heat to a very restricted area within the chip (800 degrees C) returns the cell to a 'good' state. ... According to project member HangTing Lue, the annealing can be done infrequently and on one sector at a time while the device is inactive but still connected to the power source. It would not drain a cellphone battery, he added."
It's still a long way from commercialization, but if it works on a small scale...
What are the odds they'll let something that can heat up that much on an airplane, once they read this article? :\ More seriously, I assume this is over a very, very small area, and the chip dissipates that heat within a few minutes, and that it would only be warm to the touch for a few moments... but I still gotta ask: Is there the possibility of catastrophic failure? Like if the chip was maliciously reprogrammed to trigger all the heating elements simultaniously?
#fuckbeta #iamslashdot #dicemustdie
I cant wait for the first YouTube guide telling they should put flash memory in the oven to fix it. That will translate into baking cellphones ... and you know someone will try it.
Back around 1976 I was working in a group that used Intel 4004 processors and 1702A EPROM. They found they could get more program/erase cycles out of a 1702A if they periodically baked them in an oven.
The article hints that this tech is published but not patented. Way to go!
If true we can expect many implementations in record time, lots of manufacturers trying out variations and producing affordable products.
On the other hand, if they set huge license fees on the patent it is highly likely that the only licensees will fail to produce a successfull product, and at best it becomes a niche feature for systems where it has exceptional value. For spacecraft that cannot be repaired the value is huge, for your cellphone it is a nice but marginally valuable feature.
To reiterate my comment posted on Ars two days ago when this popped:
So it's sort of a mix between traditional flash technology and the mechanism by which PCM works.
PCM does short pulses of between 400C and 700C to change the resistivity of the chalcogenide material, so generating these temperatures on microcircuitry like this isn't new.
*PCM = Phase Change Memory;
I suspect that 800C isn't out of reach, and the elements can be much coarser given you don't need them to alter a bit.
This story has popped up a few places already, and 90% of the comments are always "800C! But what if it catches fire?"
Yes, the floating gate is heated to 800C, but the volume of the heated area is on the order of a few hundred cubic nanometers. The energy involved in heating a volume that small is, well, incredibly small, and dissipates rapidly into rest of the chip. Your flash memory will not burst into flame. It will not require significantly more energy from your battery, and it will not require special clearance from the TSA to bring it on a plane.
The real challenge here is not coping with high temperatures, but rather balancing the increase in cell lifetime with the increase in die size. If the 100 million cycles number is completely accurate, then there's not much question that this technology will make its way into a lot of flash, but if that upside is only for a few (or even most) of the bits on a die, then things get more complicated
For more info run through the comments from the Ars Technica writeup of the same story: http://arstechnica.com/science/2012/11/nand-flash-gets-baked-lives-longer/
Before everyone gets worked into frothy concern about flash write cycles, keep in mind that the #1 cause of failure & data loss on Sandforce-based controllers is a toxic mess of piss-poor proprietary firmware that's brittle, bitchy, and will brick the drive in self-defense if it corrupts its internal database, then decides you're trying too hard to salvage your data by trying to use something like dd_rescue on it. Oh, and their decision to save a buck by omitting the supercapacitor that's supposed to guarantee that it always has enough power to finish its current write.
Read the Agility/Vertex 2 & 3 forums at ocz if you think I'm making this up. Basically, Sandforce drives have mandatory encryption that can't be disabled to maximize your odds of successful data recovery, but they also employ active countermeasures to detect "hacking attempts" that usually result in the drive ending up in "panic mode".
I wouldn't touch a Sandforce-tainted SSD with a dirty, tetanus-infected pole. They deserve to be sued into oblivion by class-action lawsuits. At the VERY least, they should give us the option of setting our own encryption key (to a value WE know), and a way to rip the bits from a borked drive for offline recovery. The most infuriating thing about data death by Sandforce is the knowledge that 99.99% of your data is *there*, but you aren't allowed to recover it due to their fucked up business policy.
I seriously doubt there will any detectable increase in the surface temp of the chip when this heating occurs, so that part of the story is a non-issue to me. What is much more important to me is extending the life span of the NAND flash, meaning SSD's and other devices using it will no longer have such a short useful life. I have not even considered buying an SSD so far precisely because of that. This technology, if it works as promised, will make me take the plunge! .
The older programmable logic chips of the seventies and eighties, such as bipolar PROMs and PALs, had a metal fuse for every programmed bit. Those fuses would be melted to program the chip. However, those days featured external programmers to do the melting.
The determined Real Programmer can write Fortran programs in any language.
Not one of you seems to have caught the "baking for several hours at 250C has the same effect" part, so big question: could I bake my SSD at 250C (482F for us Americaners, and easily attainable in any kitchen oven) to restore it once I exceed the flash's write limit? Or will the caps pop, die packages (or even the PCB and its traces!) de-laminate, etc?
Thanksgiving (and now Christmas) turkey fresh from the oven along with a freshened SSD sounds especially delicious!
Just place the flash on the board near my Pentium 4. I'm pretty sure it runs at 800C.
For some reason I saw self-hating
From hairyfeet (who owns a repair shop & gets a good sampling of "what actually goes on") - it's not so much the actual FLASH ram modules that go bad, but the controller firmwares that do on SSD's based on FLASH ram.
* Do I believe him? Yes. He tends not to "bullshit" and is honest (brutally so, lol, @ times)...
APK
P.S.=> I've held off buying into SSD's based on FLASH ram, & partially for the reasons you state, and moreso for those that I heard from hairyfeet noted above, as far as FLASH ram based SSD's!
However - I use one here currently, albeit one that uses 4gb DDR-2 RAM (Gigabyte IRAM) since it has a 64-bit driver, & one before it on 32-bit systems that uses PC-133 SDRAM (Cenatek RocketDrive, which I'd STILL USE if I had a 64-bit driver for it, but I do not)!
BOTH are still running perfectly, & they are respectively 8 and 11 years old iirc...
... apk
" It would not drain a cellphone battery, he added." ....of course it will not drain the battery.
dan.
Aaaaand, the world catches up with journalism.
http://blog.geeksaresexytech.netdna-cdn.com/wp-content/uploads/2008/05/computer_bomb.jpg
Interesting method of prolonging Flash's lifetime, but I frankly MRAM's characteristics are ridiculously superior to Flash in every way. Since they've got MRAM already shipping, I hope they get MRAM scaled to smaller processes well before this trick is viable on leading edge chips.
... is a really, really bad idea.
The plastics used in IC packages tend to absorb moisture from the air. Over time this moisture gets trapped in the package. If you heat a plastic IC package that has been in service to 250C there is a pretty good chance it will 'popcorn' thus destroying the chip, and often visibly rupturing the package. It can be prevented by baking the board at 50 - 80C for 12 - 20 hours, but that is going to cause other problems. No one is going to be using reflow ovens to "reset" FLASH cells.
As others have pointed out spot-heating a FLASH block to 800C would take an almost trivial amount of energy, and would only need to be done when a block fails an erase-write cycle, or as an idle task performed on blocks that have been reassigned from the 'in-use' pool to the 'dirty' pool, but have not yet been erased and assigned to the 'free' pool.
The hardware required to implement this on an existing flash design would be almost trivial.