Cruzbay, re: NROM, Mirrorbit, ORNAND, TwinFlash, NBit.
re: Perhaps I erred in saying NROM. Isn't Mirrorbit the Saifun technology, as well as 2 bit/cell? I thought that 512 Mbit Mirrorbit parts had recently been shipping for mobile phones.
No you didn't. NROM is for all practical reasons the same as Mirrorbit. Mirrorbit was developed by AMD, as well as by Saifun. Saifun was first to patenting the core technology. Saifun then contacted AMD to let them know about the possibility of a lawsuit if they would not recognize Saifun patents. AMD then had a look at Saifun's tech, and discovered among other things that Saifun was way ahead of them with quad bit. AMD took a position in Saifun (small minority position) and licensed Saifun's IP. NROM can't be but very similar to Mirrorbit. If there are any differences they are not bit. There might be other conditions in the agreement, like that AMD had first right to Mirrorbit/NROM. Lastly you're right that 512Mb Mirrorbit is shipping.
re: When the Saifun CEO says that 4 bit/cell parts are now being qualified, whose parts are these?
Again, look at the article I posted the day before yesterday. It mentions that Saifun, Spansion, Macronix and possibly Infinion codeveloped quad bit. There's a bit more tech info in a reply to that post if you're interested. ( Message 21473522 )
Your question: "Will the Spansion /Saifun NROM approach change the competitive landscape relative to Intel in high-density parts"?
Klaus' answer: "Theoretically yes. Even 2-bit/cell would make a change in this respect. But currently nobody has 2-bit/cell NROM manufacturable. Not even for older geometry nodes. Let alone for leading edge nodes. So, practically, no".
My answer: Klaus is not completely correct:
- Infineon licensed NROM and produces it at 110nm (same as AMD). Infineon calls it's NROM technology TwinFlash, and offers it with either a NOR or a NAND interface called TwinNOR and TwinNAND (like Mirrorbit and ORNAND), of which TwinNOR is sold as 256Mb device only, and TwinNAND is sold as 512Mb device only, and I think Infineon manufactures it's own flash cards.
- Macronix also started shipping NROM iirc. They call it NBit, and offer densities between 32 and 128Mb, and sell it as Mirrorbit-compatible (they have a long history of making Spansion-compatible flash), and only offer it with a NOR interface only.
Mirrorbit needs to be compared to its biggest competitor, Strataflash. Both are NOR 2b/cell technology. Strataflash is based on Multi Level Cell (MLC) floating gate technology, which works by storing 4 voltage levels per cell to store 2 bits. Mirrorbit has a bit smaller dies than Strataflash, it gets to a bit higher data capacities than Strataflash, has much higher data retention, is cheaper to produce (less process steps), but has not always proved to be easy to migrate to the next process node. Quad bit is not something that can be matched by Intel or any other producer of floating gate NOR derived products (see that post I mentioned or the reply to it), because it would require 16 different voltage levels per cell which causes the reliability of a bit to go down the drain way too fast. It also can't be matched easily in density by NAND (NAND will be for the first time more expensive too produce on the same process node). NAND however is relatively quite a bit easier to migrate to the next process node. Exactly how this will play out is not clear yet. For now Quad Bit is the holy grail for NOR products PROVIDED THAT it can be manufactured on large scale and will be migrated to the next process node at least reasonably fast. ORNAND is Mirrorbit with a NAND interface. It's attractive because it marries features from NOR and NAND. It won't be able to replace NAND, but will be successful in a niche market of the NAND market (and will hence help slow down the ascend of NAND). K, that should be enough for now.
re: Do you see the Spansion / Intel competition as a closely matched pair, or is Spansion's very different approach likely to let them pull ahead soon (or later)?
On a technical level all Spansion's new technologies (Mirrorbit, ORNAND, Quad Bit) are more advanced than Intel's core technologies. I believe though that Intel has faster floating gate products. Has been a while since I checked though.
On a bit higher level it is clear that the NROM ecosystem is expanding at a healthy rate and is here to stay for many years. Recent indications for this are aplenty: Macronix entry, Spansion ordering TSMC fab capacity, Quad Bit, ORNAND. This recent remark about scalability of NROM - both vs. floating gate and NAND - helps too: Message 21473545
K, that's btw about all I know about it.
Regards,
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