Technology Roundup: phase-change memory

As semiconductor processes shrink to ever smaller dimensions, flash memory becomes both less reliable and more complex and expensive. So far, the technology is managing to keep pace with development but physics dictates that ultimately the gates will get small enough that there simply won't be enough electrons to yield a functional memory.

Phase-change memory (PCM) offers a promising, if controversial, alternative. Indeed, the amount of research activity in the area is matched only by the spirited discussion that takes place whenever we run a feature on the topic. In this Technology Roundup, you can follow the dialogue and the evolution of the technology beginning with an overview and running up through the latest presentations.

The evolution of phase-change memory
Learn about the history and initial development activities PCM.

Phase-change memory: A rebuttal of Micron’s article
PCM may have issues with scaling, starting with current densities on the order of 10⁷ to 10⁸A/cm², thermal crosstalk, and materials interactions. This is the start of a series of perspectives features and technology reviews by Ron Neale, formerly head of the PCM program at Harris Semiconductor.

PCM scalability--Myth or realistic device projection?
PCM devices may be promising, but they do have serious issues. Neale presents a more detailed discussion of some of the concerns he aired in the article above.

PCM Scalability:The Myth (Part 2)
Neale addresses some of the comments from the Memory Designline's expert readers that were generated as a result of the first article.

PCM Progress:Temperatures rise and constituents on the move
For those, both optimists and pessimists, who follow PCM developments, IEDM2010 offered something for both camps. Cwo papers in particular, provided the not all good news, not all bad news contrasts. Ron Neale explores some of the significant points of each, along the way reviewing the impact both might have on the overall picture of PCM progress.

Phase change memory (PCM) progress report, part 2
Researchers University of Illinois Urbana-Champaign reported advances in PCM devices formed by creating narrow 20- to 30-nm gaps in 3-nm diameter carbon nanotubes. Our analyst reviews the work in his quarterly progress report.

PCM-NV progress report Part 3: A new direction using polyamorphic states
A new type of nonvolatile memory based on polyamorphous chalcogenide (PAC) transformations appeared to remove the most serious problems that have plagued PCM array progress: the high current reset pulse and, with scaling, the associated high current density and voltage.

PCM Progress Report No 4: Brains
This phase-change memory (PCM) progress report explores the use of a PCM to emulate a component of the brain, the synapse, in an impressive piece of work from Stanford University.

PCM Progress Report No 5: SSDs, MLC, and scaling
This PCM progress report takes a look at a new PCM-based SSD called Onyx, and then a multi-level PCM drift solution from IBM.

New metric for phase-change memory
A team from IBM Research-Zurich proposes a new non-resistance-based cell-state metric for phase-change memory.

PCM Progress Report No. 6: Afterthoughts
Phase change memory (PCM) faces real issues in scaling to the 20-nm node and beyond, but innovative structures and materials may help the technology fight off the flash memory challenge.

PCM Progress Report No. 6: Afterthoughts, part II
Recent advances to phase change memory (PCM) by companies like Hynix may show promise, but real progress requires a rigorous method for analyzing and reporting PCM write/erase lifetimes.

PCM Progress Report No. 7: A view of Samsung's 8-Gb array
Our PCM analyst takes a look at the data released on Samsung's 8-Gb array and what it means for the technology.