SAN FRANCISCO - At the 2011 International Solid-State Circuits Conference (ISSCC) here, Samsung Electronics Co. Ltd. will describe more details about its 1-Gbit, 58-nm phase-change memory (PRAM) technology.
The South Korean electronics giant is seeking to beat rival Numonyx, now part of Micron Technologies Inc., to the punch in the 1-Gbit PRAM race. UBM TechInsights, part of the same group that publishes EE Times, alsorecently found a NOR flash memory compatible, 512-Mbit PRAM from Samsung in a mobile handset.
But despite the hype for PRAM technology, shipments have been disappointing at best. Numonyx is late with their 1-Gbit PRAM device. And Samsung has shipped only limited quantities of PRAMs, reportedly the 512-Mbit device.
''We are shipping a little bit’’of PRAM in the market, said Oh-Hyun Kwon, president of Samsung’s semiconductor business.
''Phase-change has some very nice features,’’ he told EE Times after a keynote at ISSCC here, but the ''systems guys’’ have been ''very reluctant’’ to adopt the technology in mass quantities.
During a keynote, the Samsung executive indicated that there has been an overall reluctance by the systems houses to adopt the various next-generation memory technologies, such as PRAM, MRAM and ReRAM.
The problem is that the next-generation memory types ''are not compatible with today’s technology,’’ he said during the keynote. He urged OEMs to collaborate more with the memory houses in order to get wider adoption for the next-generation memory types.
PCM itself is based on changing the material phase and the electrical resistance of a chalcogenide layer in each memory cell through the use of electrical heating. It is an attractive technology because of its non-volatility, theoretical high density and bit-alterability and has been touted as a possible replacement for both flash memory and DRAM.
But the technology has proved difficult to commercialize and even as devices have made it to market using 90-nm and 65-nm process technologies, questions have been asked about the ability to scale the technology beyond flash memory, which is already being made at close to 22-nm.
Phase-change has been on the radar for decades, but vendors are unable to bring it into full production. Numonyx has delayed its 1-Gbit phase-change memory line, which is based on a 45-nm process. It was supposed to ship by the end of 2010. Now, it’s unclear when the device will ship.
Amid the delays, Samsung is jumping into the 1-Gbit PRAM race, although it’s unclear when the chip giant will ship that device. In a paper, Samsung said its PRAM technology is implemented in a 58-nm process, equipped with a low-power double-data-rate nonvolatile memory (LPDDR2-N) interface.
It consists of a 1-Gbit diode-switch cell array with 16 partitions. The device includes several blocks: an embedded controller, command-address (CA) input, data (DQ) channel, row address buffer, decoders, PRAM core, program buffer with 1KB of SRAM, a row data buffer (256b sized row or 32 bytes) and a data comparison write with an inversion flag (DCWI) scheme.
''The PRAM that has significantly low programming bandwidth compared to the DRAM-write (which) has a SRAM-based 1KB program buffer with 800Mb/s write throughput,’’ according to the paper.
''If the proposed DCWI enables, the program and overwrite bandwidth are measured by 6.4-MB/s and 2.3MB/s, respectively, according to the paper.
''The output data valid window (for the device) is measured to be 3.4-ns at VDD1 (at) 1.8V, 400Mb/s,’’ according to the paper. ''The tRCD value is measured to be 76ns at 85 degrees C (and) VDD1 is 1.6V.’’
The problem with PCM is that it isn't a drop in replacement for other memory types and it needs the system people to optimise for it. See for example: http://www.cs.rochester.edu/~ipek/cacm10.pdf
It seems systems designers are not yet ready to do so.
Good points everyone. In the end, potential dispruptive technologies like PCM/PRAM need to show substantial improvement that matters over today's technology. The jury is still out and that's why there's not much prodution today. Can PCM or any of the other contending "universal memories" be commercially viable for cost-efficient, volume production? Will they exceed the benefits of today’s technology by a degree large enough to justify customer and industry investment in rearchitecting? I think we are a long way away.
Actually, Numonyx 1Gbit 45nm device was supposed to ship in 2009. Then in early 2010. Then in late 2010. Now, never.
Samsung's PRAM was found in just one fake, planted, non-commercial handset (I mean one unit!) - since destroyed. Yes, the initial specs for Samsung GT-E2550 called for PRAM, but it turned out PRAM simply uses to much power and drains the battery, so the PRAM was quickly replaced back with NOR. No Samsung phone currently in production uses any PRAM. No other phones or any other commercial products use any PCM/PRAM either.
PCM/PRAM sucks. It is horribly overpriced, too slow and power-hungry in write, unreliable, with poor density, and it does not scale. It is the longest-running Techno-Ponzi scheme, but it is now coming to an end. Finally.
I am finding the statement that systems guys are slow in adopting PRAM for unknown reasons a little suspicious. I think if the advantage of PRAM was obvious everyone and his grandmother would be implementing those memories...Kris
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