Thursday, June 30th 2011

IBM Scientists Demonstrate Computer Memory Breakthrough

For the first time, scientists at IBM Research have demonstrated that a relatively new memory technology, known as phase-change memory (PCM), can reliably store multiple data bits per cell over extended periods of time. This significant improvement advances the development of low-cost, faster and more durable memory applications for consumer devices, including mobile phones and cloud storage, as well as high-performance applications, such as enterprise data storage.

With a combination of speed, endurance, non-volatility and density, PCM can enable a paradigm shift for enterprise IT and storage systems within the next five years. Scientists have long been searching for a universal, non-volatile memory technology with far superior performance than flash – today’s most ubiquitous non-volatile memory technology. The benefits of such a memory technology would allow computers and servers to boot instantaneously and significantly enhance the overall performance of IT systems. A promising contender is PCM that can write and retrieve data 100 times faster than flash, enable high storage capacities and not lose data when the power is turned off. Unlike flash, PCM is also very durable and can endure at least 10 million write cycles, compared to current enterprise-class flash at 30,000 cycles or consumer-class flash at 3,000 cycles. While 3,000 cycles will out live many consumer devices, 30,000 cycles are orders of magnitude too low to be suitable for enterprise applications (see chart for comparisons).

“As organizations and consumers increasingly embrace cloud-computing models and services, whereby most of the data is stored and processed in the cloud, ever more powerful and efficient, yet affordable storage technologies are needed,” states Dr. Haris Pozidis, Manager of Memory and Probe Technologies at IBM Research – Zurich. “By demonstrating a multi-bit phase-change memory technology which achieves for the first time reliability levels akin to those required for enterprise applications, we made a big step towards enabling practical memory devices based on multi-bit PCM.”

Multi-level Phase Change Memory Breakthrough
To achieve this breakthrough demonstration, IBM scientists in Zurich used advanced modulation coding techniques to mitigate the problem of short-term drift in multi-bit PCM, which causes the stored resistance levels to shift over time, which in turn creates read errors. Up to now, reliable retention of data has only been shown for single bit-per-cell PCM, whereas no such results on multi-bit PCM have been reported.

PCM leverages the resistance change that occurs in the material — an alloy of various elements — when it changes its phase from crystalline — featuring low resistance — to amorphous — featuring high resistance — to store data bits. In a PCM cell, where a phase-change material is deposited between a top and a bottom electrode, phase change can controllably be induced by applying voltage or current pulses of different strengths. These heat up the material and when distinct temperature thresholds are reached cause the material to change from crystalline to amorphous or vice versa.

In addition, depending on the voltage, more or less material between the electrodes will undergo a phase change, which directly affects the cell's resistance. Scientists exploit that aspect to store not only one bit, but multiple bits per cell. In the present work, IBM scientists used four distinct resistance levels to store the bit combinations “00”, “01” 10” and “11”.

To achieve the demonstrated reliability, crucial technical advancements in the “read” and “write” process were necessary. The scientists implemented an iterative “write” process to overcome deviations in the resistance due to inherent variability in the memory cells and the phase-change materials: “We apply a voltage pulse based on the deviation from the desired level and then measure the resistance. If the desired level of resistance is not achieved, we apply another voltage pulse and measure again — until we achieve the exact level,” explains Pozidis.

Despite using the iterative process, the scientists achieved a worst-case write latency of about 10 microseconds, which represents a 100× performance increase over even the most advanced Flash memory on the market today.

For demonstrating reliable read-out of data bits, the scientists needed to tackle the problem of resistance drift. Because of structural relaxation of the atoms in the amorphous state, the resistance increases over time after the phase change, eventually causing errors in the read-out. To overcome that issue, the IBM scientists applied an advanced modulation coding technique that is inherently drift-tolerant. The modulation coding technique is based on the fact that, on average, the relative order of programmed cells with different resistance levels does not change due to drift.

Using that technique, the IBM scientists were able to mitigate drift and demonstrate long- term retention of bits stored in a subarray of 200,000 cells of their PCM test chip, fabricated in 90-nanometer CMOS technology. The PCM test chip was designed and fabricated by scientists and engineers located in Burlington, Vermont; Yorktown Heights, New York and in Zurich. This retention experiment has been under way for more than five months, indicating that multi-bit PCM can achieve a level of reliability that is suitable for practical applications.

The PCM research project at IBM Research – Zurich will continue to be studied at the recently opened Binnig and Rohrer Nanotechnology Center. The center, which is jointly operated by IBM and ETH Zurich as part of a strategic partnership in nanosciences, offers a cutting-edge infrastructure, including a large cleanroom for micro- and nanofabrication as well as six “noise-free” labs, especially shielded laboratories for highly sensitive experiments.
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20 Comments on IBM Scientists Demonstrate Computer Memory Breakthrough

#1
btarunr
Editor & Senior Moderator
Many Thanks to mrw1986 for the tip.
Posted on Reply
#2
RejZoR
I'll buy a "flash" drive when it will be using this tech. I really hate the fact that you are still constantly thinking of those write cycles. Where with regular HDD, you never bothered since they have pretty much unlimited writes. But with 30 million writes, that's something completelly different. I hope this will end up in consumer devices quickly and with more reasonable price.
Posted on Reply
#4
douglatins
Dude wait 4 years to get a SSD? Get one now, they are cheap, when they botch, get a new one
Posted on Reply
#5
Steevo
So if heat is the way to change the memory what is the threshold before it changes in a black phone on a hot 100+ day?
Posted on Reply
#6
btarunr
Editor & Senior Moderator
by: arterius2
when can i buy it?
It will reach the masses in 2016.
Posted on Reply
#7
yogurt_21
so is this chemical based memory?
Posted on Reply
#8
redzo
by: btarunr
It will reach the masses in 2016.
It took NAND flash about 22 years to get mainstream, at least if you judge today's SSD's as mainstream.
2016 is an ideal, but it is not a feasible reality.
Posted on Reply
#9
hellrazor
Ha, sucks to be someone who bought an SSD now. Of course, it'll take a few years but who cares?

Wait! A thought just crossed my head! (it kinda hurt) What's the average price difference (per GB) between an SSD and a hard drive? And then what's the average speed difference between the two? How much would it cost to buy, say 1 TB hard drives and set them up in RAID 0 (?) before you reached the speed of an SSD? How much space would you end up with?

Ah, my mind is flooding!
Posted on Reply
#10
Jarman
u can raid 0 as many as you want, you wont match an SSD for access times (which is what gives an SSD its speed advantage) even if you raid 100 disks
Posted on Reply
#11
LAN_deRf_HA
by: douglatins
Dude wait 4 years to get a SSD? Get one now, they are cheap, when they botch, get a new one
How are they cheap? The only remotely affordable ones are too small to be used as a main drive. Even if I offload my pictures, videos, documents, downloads, and music to a HDD I still need at least 256 GBs to fit all my installed programs. Which is currently in the $400-500 range. Getting some little 60 GB is just stupid. You're basically just decreasing your boot time (most only reboot once a month) and startup of 5 or less programs/games. That's just a waste. SSDs are still relegated to gimmick status until that cost per GB changes.
Posted on Reply
#12
AltecV1
DRAM is lasted so damn long
Posted on Reply
#13
buggalugs
by: hellrazor
Ha, sucks to be someone who bought an SSD now. Of course, it'll take a few years but who cares?

!
Haha, you gonna stick to mechanical hard drive for another 5 years?

I'll probably buy 3 or 4 new systems with ssd's in that time.......waiting 5 years for technology is like waiting for Jesus to return......(no offence to religious peoples)
Posted on Reply
#14
hellrazor
They've been doing fine for the last 25 (at least) years.
Posted on Reply
#15
laszlo
by: Jarman
u can raid 0 as many as you want, you wont match an SSD for access times (which is what gives an SSD its speed advantage) even if you raid 100 disks
now really do you care about loosing 10 sec. from your time? not to mention the price diff.between them...

SSD is still expensive /Gb compared to classic HDD and people don't really jump in to buy and this will remain till the storage price/gb will be v.close between them
Posted on Reply
#16
RejZoR
by: buggalugs
Haha, you gonna stick to mechanical hard drive for another 5 years?

I'll probably buy 3 or 4 new systems with ssd's in that time.......waiting 5 years for technology is like waiting for Jesus to return......(no offence to religious peoples)
I only have a 2TB WD Caviar Black and i'm perfectly happy with it. System boots up in under a minute anyway for moments when i actually don't use Hybrid Sleep which wakes it up in few seconds.

I only see point in buying SSD is for either netbook or notebook. In those devices in makes loads of sense. But in desktops, only if you have loads of money. Which most don't...
Posted on Reply
#17
Tartaros
I only see point in buying SSD is for either netbook or notebook. In those devices in makes loads of sense. But in desktops, only if you have loads of money. Which most don't...
Most people who say this haven't tried a ssd and all want one when they try it. It happened with 2 friends, at first they said a ssd is so expensive for the performance you gain, it has to be cheaper first before, bla, bla bla. Then they tried my pc and now both of them they have one.

No need to defrag, no need to format, no noticeable performance degradation over time. I haven't defraged or formatted my pc for a year and a half now and everything is like the first day.
Posted on Reply
#18
MikeMurphy
by: redzo
It took NAND flash about 22 years to get mainstream, at least if you judge today's SSD's as mainstream.
2016 is an ideal, but it is not a feasible reality.
Difference today is the huge market demand for flash-type memory.

Capitalism works, and works very quickly.
Posted on Reply
#19
bostonbuddy
Big part of why I got one is NO MOVING PARTS, read write times def but I want my comp to be able to withstand years of 24/7 abuse w/o burning thru hdd's(even tho right now I'm babying my gaming rig my htpc is still running 24/7)
Posted on Reply
#20
buggalugs
by: RejZoR
I only have a 2TB WD Caviar Black and i'm perfectly happy with it. System boots up in under a minute anyway for moments when i actually don't use Hybrid Sleep which wakes it up in few seconds.

I only see point in buying SSD is for either netbook or notebook. In those devices in makes loads of sense. But in desktops, only if you have loads of money. Which most don't...
Sure, if you have a basic computer but you have a high performance expensive computer, you should be able to afford a small SSD.

SSD's are a noticable improvement over hard drives. Quicker booting, quicker installation of programs, quicker loading times for games, quicker at moving files, quicker at everything.

Its not just booting times...

When you try one you will understand....
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