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Journal of the Electrochemical Society, Vol.155, No.6, H421-H425, 2008
Nonvolatile memory-switching behaviors of phase-change memory devices using Ti-Si-N heating layers
To scale the phase-change memory cell to a practical level, the programming current of the memory device must be reduced. In this work, the use of a Ti-Si-N heating layer was proposed due to its controllability in electrical resistivity, stability at high temperatures, and compatibility with process. The electrical resistivity of Ti-Si-N films could be controlled in the range from 500 to 3000 mu Omega cm when the sputtering power of Si was varied from 40 to 80 W. For the prepared Ti-Si-N films, the surface smoothness and the immunity to oxidation at higher temperatures were confirmed to be much better than those of the conventionally used TiN heating layer. We actually fabricated the phase-change memory devices employing Ti-Si-N heating layers and compared their device behaviors with those of the control device using TiN. The required current for reset and the required time for set were reduced from 14 to 8 mA and from 500 to 350 ns, respectively. The rewritable cycles also improved from 1.4 to 8.4x10(6) times by replacing TiN with Ti-Si-N. The obtained results suggest that the proposed Ti-Si-N heating layer is a promising candidate to improve the device performance in all aspects for phase-change memory application. (c) 2008 The Electrochemical Society.