IBM breakthroughs with PCM memories

IBM has for several years to work on phase change memory (PCM), and, in recent hours, has provided an important update on the progress of the search. Such non-volatile type memory offers considerable advantages both with respect to the flash memories, both with respect to the RAM modules: are the fastest of the first, very resistant and, as mentioned, are of non-volatile type, so do not lose the data stored in the absence of power supply, as is the case with the RAM memory. Limitations related to the technology used caused them so far use in a production environment, but something is moving, as emphasized by IBM researchers.

The PCM memories exploit the physical properties of a calcogenura alloy (formed by Germanium, Antimony, and Tellurium), similar to that used in the rewritable optical discs. The alloy, crossed by a determined change of phase current intensity, passing from the crystalline to the amorphous, according to a reversible process. The crystalline phase (state with low electrical resistance), corresponds to the logic state 1, while the amorphous phase (state with high electrical resistance) corresponds to logic state 0, this allows to create, in fact, a true solid state memory which offers the advantages described in the opening. Until now, however, the main limitations were related to the limited capacity and the high costs.

The novelty communicated in the last hours by IBM concerns the development of new technologies that have the 3-bit storage made possible for PCM cell, an extremely important goal, taking into account that, previously, the upper limit was equal to 1 bit. As emphasized Haris Pozidis IBM Research:

Achieve 3-bit per cell represents a significant milestone because at this density the cost of the PCM memories will be significantly lower than that of DRAM and closer to the cost of flash memory.

The scenarios of use that appear on the horizon are particularly interesting: IBM promises, for example, the hypothesis of the realization of hybrid-type storage solutions in which the PCM modules operate in symbiosis with the conventional flash memory to perform the memory function smartphone cache. The IBM researchers point out in this regard:

The operating system of a smartphone could be stored in the PCM module, enabling the launch of the smartphone in seconds

The PCM memory, may act as substitutes for the SSD in work areas that require significant data reading speed: PCM modules can read the data stored in less than 1 microsecond, while SSDs do not fall below 70 microseconds.

In whole the enterprise database may be stored in the PC memory making it extremely fast query processing for time-critical online applications, such as financial transactions

RAM memories are even faster, but in certain contexts the PCM modules may be used as a storage solution "universal" capable of replacing both the RAM, both the flash memory, not to mention the cloud-based applications of artificial intelligence, and the use in data centers. In addition to the higher speed of the flash memory, in fact, the PCM modules can boast a longer life: 10 million write cycles to the phase change memories, compared with about 3000 of flash memory cycles. The progress made managing to store 3-bit per cell are objectively important, but at the moment, we do not know when will the PCM modules will be used in a commercial product.