A key breakthrough in phase change memory (PCM) research was announced jointly by Intel Corp. and memory-maker Numonyx last week. PCM is a relatively new non-volatile memory technology that combines many of the benefits of today’s various memory types.
For the first time, the two companies reported, researchers demonstrated a 64 Mb test chip that enables the ability to stack, or place, multiple layers of PCM arrays within a single die. The achievements are a result of an ongoing joint research program between Numonyx and Intel that has been focusing on the exploration of multi-layered or stacked PCM cell arrays.
These findings may pave the way for building memory devices with greater capacity, lower power consumption, and optimal space savings for random access non-volatile memory and storage applications.
Intel and Numonyx researchers can now demonstrate a vertically integrated memory cell, called PCMS (phase change memory and switch). PCMS is comprised of one PCM element layered with a newly used ovonic threshold switch (OTS) in a true cross point array. The ability to layer or stack arrays of PCMS provides the scalability to higher memory densities while maintaining the performance characteristics of PCM.
Memory cells are built by stacking a storage element and a selector, with several cells creating memory arrays. Intel and Numonyx researchers were able to deploy a thin film, two-terminal OTS as the selector, matching the physical and electrical properties for PCM scaling. With the compatibility of thin-film PCMS, multiple layers of cross point memory arrays are now possible. Once integrated together and embedded in a true cross point array, layered arrays are combined with CMOS circuits for decoding, sensing, and logic functions.
“We continue to develop the technology pipeline for memories in order to advance the computing platform,” says Al Fazio, Intel fellow and director, memory technology development. “We are encouraged by this research milestone and see future memory technologies, such as PCMS, as critical for extending the role of memory in computing solutions and in expanding the capabilities for performance and memory scaling.”
Greg Atwood, senior technology fellow at Numonyx, says the results of the research are “extremely promising. ” He explains, “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.”
More information about the memory cell, cross point array, experiment, and results will be published in a joint paper titled “A Stackable Cross Point Phase Change Memory,” and will be presented at the 2009 International Electron Devices Meeting in Baltimore, Md., on Dec. 9. The paper is co-authored by Intel and Numonyx technologists and will be presented by DerChang Kau, Intel senior principal engineer.