IBM chip 100x faster than most advanced flash memory

July 4, 2011

IBM's prototype PCM (credit: IBM Research)

Scientists at IBM Research have demonstrated that phase-change memory (PCM) can reliably store multiple data bits per cell over extended periods of time.

The scientists used advanced modulation coding techniques to mitigate the problem of short-term drift in multi-bit PCM, which causes the stored resistance levels to shift over time, and, in turn, creates read errors. Up to now, reliable retention of data has only been shown for single bit-per-cell PCM.

The scientists implemented an iterative “write” process to overcome deviations in the resistance due to inherent variability in the memory cells and the phase-change materials. Despite using the iterative process, the scientists achieved a worst-case write latency of about 10 microseconds, which represents a 100x performance increase over even the most advanced flash memory on the market today.

The scientists were able to mitigate drift and demonstrate long-term retention of bits stored in a subarray of 200,000 cells of their PCM test chip, fabricated in 90-nanometer CMOS technology.

IBM’s breakthrough advances the development of low-cost, faster and more durable memory applications for consumer devices, including mobile phones and cloud storage, as well as high-performance applications, such as enterprise data storage.

Ref.: E. Eleftheriou, et al., Drift-tolerant Multilevel Phase-Change Memory (presented at the 3rd IEEE International Memory Workshop in Monterey, CA)