Earlier this year, Intel and Micron's joint NAND manufacturing venture (IMFT) announced it had produced 64Gb (8GB) MLC NAND on a 20nm process. Most IMFT NAND that's used in SSDs are built using a 25nm process - the move to 20nm reduces die size and in turn reduces cost over time. A single 8GB 2-bit-per-cell MLC NAND die built on IMFT's 25nm process measures in at 167mm2, while the same capacity on IMFT's 20nm process is 118mm2. Early on in any new process wafers are more expensive, but over time NAND costs should go down as they are more a function of die size than process technology.

Today Intel and Micron are both announcing a second generation 20nm part at a 128Gb (16GB capacity). This isn't just a capacity increase as the 128Gb 20nm MLC NAND features an ONFi 3 interface rather than ONFI 2.x used in the earlier 64Gb announcement and older 25nm parts. ONFI 3 increases interface bandwidth from a max of 200MT/s (IMFT 25nm was limited to 166MT/s) to 333MT/s. This has a direct impact on sequential read performance for example, as most of those operations tend to be interface bound. Note that when I'm talking about interface speed I'm referring to the maximum speed allowed between the SSD controller and the NAND itself (e.g. an 8-channel ONFI 3 controller would have 8 x 333MT/s interfaces to NAND). 

Alongside the faster interface speed is yet another increase in page size. The move to 25nm NAND brought about 8KB pages (up from 4KB), the 128Gb 20nm MLC NAND solution uses 16KB pages. Because of the changes to the interface speed and page size we won't see drives/controllers use the 128Gb devices for another 1 - 1.5 years. The reason for the delay in incorporating this NAND into SSDs is two fold: 1) A 128Gb 20nm die will be pretty big (2x the size of a 64Gb die), and it'll take time for yields to improve to the point where it's cost effective, and 2) a larger page size and new interface both require a revision to the controller & firmware. Intel and Micron have both confirmed that they will not be using the 128Gb parts in SSDs until 2013.

The 128Gb 20nm parts will go into mass production in Q2 2012, giving IMFT ample time to ramp up production and work on yields before more functional deployment inside SSDs. SSD makers (and other consumers of NAND) will be able to get octal die packages using 128Gb NAND, meaning a single package can feature up to 128GB of NAND. This also paves the way for 1TB SSDs with only eight chips, or 2TB SSDs with both sides of a 2.5" PCB populated. The new Ultrabook/MacBook Air gumstick SSD form factor will be able to accommodate 512GB - 1TB of NAND using these 128Gb ODP devices.

While 128Gb parts are still some distance away, 64Gb 20nm NAND from IMFT is in mass production today.  Again, don't expect to see the 64Gb parts in use in SSDs until the middle of 2012 however. Controller vendors need time to ensure support for the NAND and validate/cross-their-fingers-and-hope-it-works with their designs. IMFT also needs time to build up inventory and ensure good yields. Remember the 64Gb parts retain the ONFI 2.x support and 8KB page size of IMFT's 25nm NAND.

The big question is endurance, however we won't see a reduction in write cycles this time around. IMFT's 20nm client-grade compute NAND (used in consumer SSDs) is designed for 3K - 5K write cycles, identical to its 25nm process. IMFT have moved to a new cell architecture with a much thinner floating gate. The 20nm process is also a high-K + metal gate design, both of which contribute to maintaining endurance ratings while shrinking overall transistor dimensions.

SSDs have fallen in prices tremendously over the past few years. We're finally approaching $1/GB in many cases. With 20nm NAND due out next year, I'd say we're probably within a year of dropping below $1/GB. 

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  • Paul Tarnowski - Wednesday, December 7, 2011 - link

    A few clarifications, since I wrote that comment in parts.

    When I wrote about casual users not spending more dollars, I meant that with the size of HDD (hundreds of GB) that come with computers (manufacturing costs of a platter of any given size is similair, it's just a matter of capital costs of R&D and equipment), it becomes economical to offer SSDs on most computers. This is especially true when most people tend to keep their photos on an external drive.

    I also meant that I didn't mind (relatively speaking) the computer booting time before I got an SSD, as I understood the why of it. Now I expect to be able to open Firefox in 20 seconds after turning on power, which only doesn't happen when Windows was left doing an update.

    And I rather turn my computer off, when I turn it off at all, completely these days, seeing as I can keep my computer on and running for weeks or months.
  • handzilla - Thursday, December 8, 2011 - link

    Thanks for your feedback and insights.

    Now, regarding your comment where you said:
    Cellphones will not replace dedicated computers any time soon. Not when they are at least a decade behind in power and definitely not unless the size limitations of interfacing with them are overcome

    i suppose it depends on how much power will be needed to process what/which app?

    As for interfacing with cellphones, Motorola's Atrix + LapDock seems like a good/acceptable direction?

    The concept suggests that cellphones have/will soon have enough/excess processing power for most apps which do not needing supercomputer processing power, and for more processing power, say for 3D FPS/MMORPG-types of gaming or for massive floating-point number crunching, something like a LapDock with a more powerful GPU(s) is possible.

    Now this makes me wonder if it is now feasible to manufacture modular GPUs, which can be upgraded just like a PC, so instead of replacing GPUs why not just add more processing hardware!?

    Oops. i digress.

    Perhaps SSDs should be incorporated into "smart/internet" TVs which can also double-duty as huge monitors? These TVs could then also record & store & stream videos, and help bring down the cost of SSDs?!

    To bring the cost of SSDs down even faster, yet-to-be-produced faster & higher-capacity SSDs could be pre-ordered in massive bulk quantities (for a lower target price point) by "cloud" storage providers (as well as "tier 1" PC OEMs) who will be like airline "launch customers" that pre-order airplanes from Boeing/Airbus/et.al). The (serious) money that can be raised will be cheaper than borrowing from any bank!

    Then again, maybe free plus dirt-cheap "cloud" storage is the way to go. Wait, i just realized that Facebook is already giving free storage for our precious photos. As for most of our music collection, plus anything else which should be archived, well, we can always use DVDs or BDs.

    Looks like i can wait until SDDs can be close to or almost as cheap as HDDs (with capacities being equal).

    Hopefully, it won't be a long wait.
  • galfert - Wednesday, December 7, 2011 - link

    I don't understand the $1/GB comment in the article. Is it a typo? Is is supposed to say $1/Gb instead? Or maybe the 1 shouldn't be there an it should read jus $/GB.

    Someone please shed some light. Thanks.

    Confused -- * shrug *
  • galfert - Wednesday, December 7, 2011 - link

    Never mind.....I got it. I wasn't awake yet.
  • djshortsleeve - Wednesday, December 7, 2011 - link

    Ive been running the 128 GB Crucial C300 since early 2011 in my 2500k machine. It has been snappy and very reliable. I have had about 3-4 freezes during that time where the machine appeared to lock up, but came out and back to normal in about 1 min. Id say thats solid.

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