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Phase-change random access memory—a scalable technology
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by S. Raoux,
G. W. Burr,
M. J. Breitwisch,
C. T. Rettner,
Y. Chen,
R. M. Shelby,
M. Salinga,
D. Krebs,
S. Chen,
H. Lung,
and C. H. Lam
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Non-volatile random access memory, using resistance contrast in phase-change materials (PCRAM), is a promising technology for future storage-class memory. However, such a technology can only succeed if it can scale smaller in size, given the increasingly tiny memory cells that are projected for future technology nodes (i.e. generations). We first discuss the critical aspects that may affect the scaling of PCRAM, including materials properties, power consumption during programming and read operations, thermal crosstalk between memory cells, and failure mechanisms. We then discuss experiments that directly address the scaling properties of the phase-change materials themselves, including studies of phase transitions in both nanoparticles and ultra-thin films as a function of particle size and film thickness. This materials work directly motivated the successful creation of a series of prototype PCRAM devices, which have been fabricated and tested at phase-change material cross-sections with extremely small dimensions as low as 3 nm × 20 nm. These device measurements not only provide a clear demonstration of the excellent scaling potential offered by this technology, but they are also consistent with the scaling behavior predicted by extensive device simulations. Finally, we discuss issues of device integration and cell design, manufacturability, and reliability.
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