Intel and Numonyx, an Intel-ST Microelectronics joint venture, have today announced what they claim to be a key breakthrough in the research of phase-change memory (PCM), enabling chips with higher densities than was available before.
As part of a research program, engineers from Numonyx and Intel have for the first time proven that layers of PCM arrays can be stacked within a single die. Intel believes that the breakthrough - demonstrated with a 64Mb test chip - will pave the way for greater-capacity storage solutions, with Intel's director of memory technology development, Al Fazio, suggesting that "in theory, we can achieve higher areal densities for storage than what NAND can achieve".
PCM, a form of non-volatile memory, has long been touted as the successor to traditional storage technologies such as DRAM and Flash memory. Using the application of heat to change states, PCM manipulates chalcogenide glass to switch between amorphous (in which atoms are loose) and, at a higher temperature, crystalline (where atoms are rigid) states, leading to binary 1 for crystalline and 0 for amorphous. The technology hopes to offer DRAM-like speeds in a non-volatile form.
The newly discovered stacked technology - dubbed PCMS (phase-change memory and switch) - utilises a phase-change memory layer equipped with a "thin film, two-terminal Ovonic Threshold Switch" in a true cross point array. As a result of the compatibility of thin-film PCMS, multiple layers can be stacked together and combined with CMOS circuits to create complete higher-density chips.
Although still very much at the research stage, Intel believes that PCMS plays a critical part in "extending the role of memory in computing solutions and in expanding the capabilities for performance and memory scaling".
Commenting on the breakthrough, senior technology fellow at Numonyx Greg Atwood states that "the results show the potential for higher density, scalable arrays and NAND-like usage models for PCM products in the future."
"This is important as traditional flash memory technologies face certain physical limits and reliability issues, yet demand for memory continues to rise in everything from mobile phones to data centers," he adds.
In the race for next-gen storage supremacy, PCM is up against the likes of Spin Torque Transfer (STT-RAM) - a technology seen as a potential successor for the modern hard drive. Both technologies still have some way to go, but for the physicists out there, Intel and Numonyx will be publishing a joint paper titled "A Stackable Cross Point Phase Change Memory" at the 2009 International Electron Devices Meeting on December 9th.
One layer of the PCMS array
fully integrated with a CMOS technology.
The memory-cell stack, including rows and columns, is shown sandwiched
between metal lines M2 and M3 (not shown).
