A study of the switching mechanism and electrode material of fully CMOS compatible tungsten oxide ReRAM

Tungsten oxide (WOX) resistive memory (ReRAM), a two-terminal CMOS compatible nonvolatile memory, has shown promise to surpass the existing flash memory in terms of scalability, switching speed, and potential for 3D stacking. The memory layer, WOX, can be easily fabricated by down-stream plasma oxidation (DSPO) or rapid thermal oxidation (RTO) of W plugs universally used in CMOS circuits. Results of conductive AFM (C-AFM) experiment suggest the switching mechanism is dominated by the REDOX (Reduction-oxidation) reaction—the creation of conducting filaments leads to a low resistance state and the rupturing of the filaments results in a high resistance state. Our experimental results show that the reactions happen at the TE/WOX interface. With this understanding in mind, we proposed two approaches to boost the memory performance: (i) using DSPO to treat the RTO WOX surface and (ii) using Pt TE, which forms a Schottky barrier with WOX. Both approaches, especially the latter, significantly reduce the forming current and enlarge the memory window.

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