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Samsung preps 8-Gbit phase-change memory

11/29/2011 11:28 AM EST
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R G.Neale
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re: Samsung preps 8-Gbit phase-change memory
R G.Neale   12/5/2011 9:50:09 AM
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Mr Rbtbob-With respect to terbium and mechanisms of operation, as I have written somewhere here in another comment, reduction to practice is necessary. That is reduction to practice in an environment that considers all the variables that will allow the device to be produced in array form. One thing is sure for any new compositions that are suggested as the active material for PCM or threshold switches, there is one question that must now be asked. It is, are they immune from the effects of element separation, from whatever the cause. J, E, or crystallization rejection processes.

rbtbob
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re: Samsung preps 8-Gbit phase-change memory
rbtbob   12/4/2011 4:46:24 PM
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I agree that the patent is for a design that uses a combination of components that are not quite perfected. It is interesting that it proposes moving away from the silicon wafer process. I believe some PCM researchers are developing the concept that a PCM cell would benefit from a reduction in the cell diameter. A diameter that is small enough to restrict the cell material molecules into having fixed pivot points as the conductive matrix forms and un-forms. I have a personal theory that this effect can be assisted by doping the cell material with Terbium. Maybe the same effect can improve the threshold switches.

R G.Neale
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re: Samsung preps 8-Gbit phase-change memory
R G.Neale   12/3/2011 10:40:08 AM
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Mr rbtbob-I think the patent you mention is one of those that might be useful for promotion and VC activities, but little else. For me reduction practice is necessary before I would become a believer. Any discussion of threshold switches requires an answer to the simple question. Why has nobody been able demonstrated a long lived free running oscillator using the negative resistance of a threshold-switch; that is an oscillator that runs for more than a maximum of a few thousand cycles before device failure. When the reason for that is fully explained or a demonstration provided, the relevance of the patent can be discussed further. I think the answer to the free running oscillator problem points to the fundamental mechanism of threshold switching. I would suggest a clue will be found from the composition analysis of the threshold switch after it has been used in oscillator experiments.

R G.Neale
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re: Samsung preps 8-Gbit phase-change memory
R G.Neale   12/2/2011 9:13:28 PM
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Eista and Resistion--- post the IBM work, I think most of those trying to understand the PCM element separation (ES) problem now agree, that once the chalcogenide becomes molten the driving force for ES is electric field, that is it is an electrochemical process. During reset and before the chalcogenide becomes molten conventional electro-migration driven by current density is in play. Current density is important because it will drive electro-migration in the passive and active components in the matrix. The reset current density can always be reduced, but that usually extracts a performance penalty in some other parameter. If you are Samsung then it appears from their PRAM cell…..VLSI2010 paper you can reduce w/e power in the same PCM structure (their figure 12) without consequences. Ignoring the fact that at some point in the process of that reduction the device will fail to operate and the lifetime will fall to zero. Even though their own data tends to indicate a maximum they ignore the reality of a maximum lifetime as a function of reducing w/e power. In that same paper they do not consider that at some levels of reset (high current) the molten material will have metal as the electrodes, while at low reset current the electrodes in contact with the molten material will be crystalline chalcogenide. This means they are most likely extrapolating a single curve from what are in effect a series of different devices. I think we will need to look very carefully at the PCM related claims for PCM performance at both IEDM 2011 and ISSCC 2012. However, a serious and competitive product announcement (8G-bit or 1G-bit even),with (public) data sheets will kill much of the discussion.

resistion
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re: Samsung preps 8-Gbit phase-change memory
resistion   12/2/2011 6:20:00 AM
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2.5 MA/cm^2 is comparable to STT-MRAM. But it's still a little too hard to ask 45 nm MOSFET to provide the 30 uA.

eista
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re: Samsung preps 8-Gbit phase-change memory
eista   12/1/2011 4:21:55 PM
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The reset current density issue has called attention in the industry. Will be interesting to see the 2011' IEDM paper from Macronix with 30uA reset current with 39nm contact size. The current density will be less than 10MA/cm^2. Does Samsung have motivation to move to PCM mass production now, just imaging Samsung has PCM technology ready? Probably no, since Samsung has the biggest DRAM/NAND memory market share now and there is no other big player in PCM.

resistion
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re: Samsung preps 8-Gbit phase-change memory
resistion   11/30/2011 1:40:54 PM
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Samsung to do 10 nm NAND within a year. http://4lovestoned.com/10-nm-nand-flash-volume-production-samsung-process-speed-who-can-argue-2126.html

flyingunderradar2
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re: Samsung preps 8-Gbit phase-change memory
flyingunderradar2   11/30/2011 2:33:23 AM
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Mr Lowrey is still at it Mr. Bauer and that is why you are still posting as "Volatile Memory." You don't like the fact that Lowrey has the Edison perspiration factor and has savored success. What is your claim to fame?

ilmenauer
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re: Samsung preps 8-Gbit phase-change memory
ilmenauer   11/30/2011 2:22:07 AM
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I quite agree. And i presume that Samsung engineers/managers understand it as well. But you should also consider, that large teams were working on PCM development, so now they just can not so simply admit that their bet has lost (and lose face doing it, it is Asian company, after all). So some activity will be continued, at least until major reshuffle in leadership happens and new managers could scrap the project (to everybody's relief).

flyingunderradar2
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re: Samsung preps 8-Gbit phase-change memory
flyingunderradar2   11/30/2011 2:21:34 AM
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Keep short Mr. Bauer.

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