ISSCC: Samsung preps 8-Gbit phase-change memory

11/29/2011 7:07 AM EST

They're also reporting on sub-20 nm NAND, that should be more interesting.

11/29/2011 7:28 AM EST

If it's like last year, they still use a row data buffer.

11/29/2011 11:57 AM EST

Given the technical challenges, what have Samsung's engineers done to make the commercialization of PCM viable?

11/29/2011 12:27 PM EST

The author, Mr. Peter Clarke, knows very well that phase-change memory is a techno-Ponzi scam and that Samsung has long abandoned any efforts to commercialize this 40-year old technology in volume, after the disastrous performance of the 512Mbit PRAM MCP in a pre-production Samsung mobile phone last year (power consumption issues and write speed). Here is the proof: Can Mr. Clarke tell us where we can buy even a 1-Gbit phase-change memory chip? Phase-change memory will never be commercialized in volume as it has poor density, slow write speed, dismal durability, overheats, and cannot scale. However, phase-change memory remains a perfect vehicle for unscrupulous "researchers" to get a free vacation in the United States.

11/29/2011 1:50 PM EST

Since they are going to display the PCM with current manufacturing technology, Samsung might be spending money and efforts behind the development of the Random Access PCM and Nonvolatile PCM, to know which one becomes preferable we will have wait along with time.

11/29/2011 6:17 PM EST

To date (including the one to be discussed at IEDM 2012 in a week or so) there will have been four 1 G-bit PCM memory chips from different manufacturers. I think in order to judge the future prospects for PCM, rather than requesting an answer to the question, where can I buy a 1G-bit PCM, it is more important to know the real and true reasons why you cannot buy one.

My view is there are two essential needs for the success of the introduction of any new memory technology; at any point in time it must offer an order of magnitude performance improvement over what is already available. Of even greater necessity, and to build confidence is the need for a continuity of products of increasing bit density and performance, accompanied by design wins. In the product continuity steps for monolithic PCM from 512M-bit to 8M-bits, the missing steps of devices with bit capacity of 1G-bit and 4G-bit is unusual to say the least. It maybe the powers that be at Samsung recognized they have slipped too far behind and decided that it has to be 8G-bit now or nothing. In the past ISSCC was always made more exciting waiting for the product announcement a week or so after the scientific paper was presented. Therefore we might have two bits of PCM news to look forward a 1G-bit product announced by Hynix, followed by the 8G-bit from Samsung in April. Personally on that count, based on the history of PCM developments todate I am less than optimistic.

11/29/2011 7:30 PM EST

Mr Non Volatile Memory:-I think given the right product and demand, manufacturing costs can in most cases be reduced as part of the normal learning curve.
Unless, that is, those manufacturing costs are related to yield and linked to problems of a fundamental nature. If the VLSI2010 paper on a high performance PRAM cell (17 x 7.5nm)from Samsung is the precursor for the structure used in the 8G-bit, what I consider are unsafe extrapolations and conclusions in that work gives rise to my lack of optimism as far as the 8G-bit device is concerned. In that cell the calculated reset current density was 6.2 x10E+7Amps/sq-cm, it will be very interesting to see how Samsung have dealt with that as far as both matrix isolating devices and electro-migration as well as element separation in the PCM material from whatever its causes (J or E linked through the electrical conductivity of molten chalcogenide).

11/29/2011 7:53 PM EST

Samsung still has groups working on different types of memories, so they're bound to publish stuff that will attract detractors as well as supporters.

11/29/2011 8:40 PM EST

Tyler Lowrey (Ovonyx) was issued patent 8,053,753 on 8 November for a complete thin film device with PCM and logic based on chalcogenide threshold switches. I believe these thin film computers will greatly advance the creation of robotic personal assistants. It will be a fairly straight-forward tweak to build in the cognitive functions recently documented here on EE Times. I hope Stan Ovshinsky lives long enough to see these robots demonstrate the culmination of his extraordinary work.

11/30/2011 8:40 AM EST

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

12/2/2011 4:13 PM EST

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.

12/3/2011 5:40 AM EST

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.

12/4/2011 11:46 AM EST

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.

12/5/2011 4:50 AM EST

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.