Scientists at IBM Research have demonstrated that a relatively new memory technology, known as Phase-Change Memory (PCM), can reliably store multiple data bits per cell over extended periods of time. This significant improvement 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.

Phase-Change Memory (PCM) - Reliable High-Speed Memory TechnologyWith a combination of speed, endurance, non-volatility and density, PCM can enable a paradigm shift for enterprise IT and storage systems within the next five years. Scientists have long been searching for a universal, non-volatile memory technology with far superior performance than flash – today’s most ubiquitous non-volatile memory technology.

The benefits of such a memory technology would allow computers and servers to boot instantaneously and significantly enhance the overall performance of IT systems. A promising contender is PCM that can write and retrieve data 100 times faster than flash, enable high storage capacities and not lose data when the power is turned off. Unlike flash, PCM is also very durable and can endure at least 10 million write cycles, compared to current enterprise-class flash at 30,000 cycles or consumer-class flash at 3,000 cycles. While 3,000 cycles will out live many consumer devices, 30,000 cycles are orders of magnitude too low to be suitable for enterprise applications.

To achieve this breakthrough demonstration, IBM scientists in Zurich 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, which in turn creates read errors. Up to now, reliable retention of data has only been shown for single bit-per-cell PCM, whereas no such results on multi-bit PCM have been reported.