An article by Micron senior fellow Greg Atwood contributed to EE Times, entitled
The evolution of phase-change memory, has excited considerable response as well as a counterpoint article entitled
Phase-change memory: A rebuttal of Micron's article.
When asked if Micron continued to support phase-change memory Ed Doller, vice president and chief memory systems architect with Micron and formerly chief technology officer with Numonyx, told
EE Times: "Absolutely I can confirm that." He added that 80 to 90 percent of the staff that report to him are working on phase-change memory.
Phase-change memory has shown promise as a potential non-volatile replacement for flash memory and DRAM but the technology has been slow to make it out of the laboratory. As the situation stands PCM is behind the rival technologies in terms of both memory capacity in bits and the cost of manufacture. This has given rise to speculation that the technology may be a curiosity that ultimately fails to impact the market. Micron has one phase-change memory product line that customers can buy; the Omneo 128-Mbit device implemented using a 90-nm process technology but Numonyx, and now Micron, have yet to produce a promised follow-on 1-Gbit memory using a 45-nm process technology.
When asked if Micron would respond directly to the technical questions posed within the Internet pages of
EE Times, Doller said that Micron has put some technical information in the public domain through the presentation of papers at conferences such as the International Electron Devices Meeting and that other technical material it shares with companies under non-disclosure agreements.
Doller did not disagree with the statement that other memory technologies are already down at 3x-nm and heading for 2x-nm so that for PCM to have a future it must compete at those geometries and beyond.
Doller responded: "There will be challenges but we are on a path to scale the technology further than any of the incumbents, by which I mean NOR, NAND and DRAM." He declined to discuss detailed solutions to the challenges to the scalability of PCM. These could include the non-scaling of current density, electro-migration and thermal cross-talk, amongst others.
When asked about the 1-Gbit device, Doller said: "We will be sampling a 45-nm 1-Gbit to customers this year. Volume production is in 2011. There is no doubt in my mind about this."
Doller said that PCM is targeting mobile phone applications as well computing applications. A different emphasis apparent in Atwood's article was due to the fact that the article was only addressing computing platform applications where Doller said the company does expect design wins in storage applications to come first.
"Is there value in putting expensive PCM in there? When you think about latency, yes," said Doller outlining that magnetic media have delays of the order of milliseconds compared to microseconds for NAND flash solid-state memory, which compares to nanoseconds for PCM. "There is also a case for endurance. NAND endurance is reducing rapidly as we scale," asserted Doller. There continues to be an opportunity in mobile handset memory, said Doller.
When asked about what geometry node Micron would target for the next device after 45-nm and what progress was being made developing a next-generation phase-change memory IC, Doller said: "We are working on what comes next," but declined to comment further.