IBM Scientists Achieve Storage Memory Breakthrough

IBM Research – Latest Memory Technology – Phase-Change-Memory –PCM

Scientist at IBM Research, have for the first time demonstrated reliably storing 3 bits of data for each cell utilising a latest memory technology called phase-change memory – PCM. The existing memory landscape tends toextentfrom respected DRAM to hard disk drives to universal flash. However in the last several years PCM has attracted the attention of the industry as a probable universal memory technology based on its mixture of read/write speed, non-volatility, density and endurance.

For instance PCM does not lose data when it tends to power off unlike DRAM. The technology could endure at least 10 million write cycles in contrast to an average flash USB stick that tends to top out at 3,000 write cycles. The break-through of the research has provided quick and easy storage in catching the exponential growth of data from the mobile devices as well as the Internet of Things.

IBM scientists tend to envisage standalone PCM together with hybrid application that would unite PCM and flash storage together with PCM as an exceedingly fast cache. For instance the operating system of a mobile phone could be stored in PCM permitting the phone to launch within a few seconds. In the initiative space, the complete database can be stockpiled in PCM for fast query processing for time-critical online application like financial transaction.

Two Stable States – Amorphous/Crystalline

Machine learning processes utilising huge datasets would see a rapid boost on reducing the latency overhead while reading the data between iterations. The PCM materials tend to display two stable states, namely the amorphous – without a clearly defined structure and crystalline – with structure phases, of high and low electrical conductivity, respectively. Scientists at IBM and the other institutes had successfully demonstrated the potential to store 1 bit per cell in PCM earlier. However, presently at IEEE International Memory Workshop in Paris, for the first time, the IBM scientists are presenting, successfully stored 3 bits per cell in a 64k-cell array at higher temperatures and after a million endurance cycles.

 Dr Haris Pozidis, author of the paper and the manager of non-volatile memory research at IBM Research – Zurich had informed that `phase change memory was the first instantiation of the universal memory with properties of DRAM and flash, thus answering one of the grand challenges of the industry.

Novel Coding/Detecting Scheme Employed

He further added that reaching three bits per cell seems to be a significant milestone since at this density, the cost of PCM tends to be significantly less than DRAM and nearer to flash. In order to attain multi-bit storage, IBM scientists had developed a couple of innovative enabling technologies, a set of drift-immune cell-state metrics and drift-tolerant coding with detection schemes.

The new cell-state measure a physical property of the PCM cell more precisely, which tends to remain stable over a period of time and are hence insensitive to drift, affecting the stability of the electrical conductivity of cell with time. In order to provide extra strength of the data stored in a cell over ambient temperature fluctuation, a novel coding as well as detecting scheme had been employed.

The scheme tends to adaptively change the level threshold which is used in detecting the stored data of cell so that they follow variation owing to temperature changes. The outcome is that the cell state can be read reliably over long period of time after the memory is programmed and hence offers non-volatility.