Low Power and Improved Switching Properties of Selector-Less Ta2O5 Based Resistive Random Access Memory Using Ti-Rich TiN Electrode

The effects of TiN top electrode composition (TiN vs Ti-rich TiN) on the resistive switching characteristics of selector-less TiN/TiO x /Ta 2 O 5 /TiN resistive random access memory (ReRAM) are investigated. Ti-rich TiN enables TiO x to have a higher concentration of oxygen vacancy and reduce barrie...

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Published inJpn J Appl Phys Vol. 52; no. 4; pp. 04CD05 - 04CD05-5
Main Authors Kim, Beomyong, Kim, Wangee, Kim, Hyojune, Jung, Kyooho, Park, Wooyoung, Seo, Bomin, Joo, Moonsig, Lee, Keejeung, Hong, Kwon, Park, Sungki
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 25.04.2013
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Summary:The effects of TiN top electrode composition (TiN vs Ti-rich TiN) on the resistive switching characteristics of selector-less TiN/TiO x /Ta 2 O 5 /TiN resistive random access memory (ReRAM) are investigated. Ti-rich TiN enables TiO x to have a higher concentration of oxygen vacancy and reduce barrier height between top electrode and TiO x . This leads to higher on/off current ratio and lower operation voltage without degradation of non-linearity which is the important factor for selector-less type ReRAM, compared to the stoichiometric TiN resistor stack. Consequently, it is verified that the switching mechanism is hybrid combination of filament formation and redox reaction in switching operation. This work is applicable to both high density and cost-effective ReRAM.
Bibliography:(a) Process flow of the fabricated ReRAM structure and (b) cross-section TEM image. The bottom electrode contact (BEC) size is 50 nm. Definition of non-linearity ($\mathit{Kw}$). XPS Ti 2p spectra of TiO x structures. (a) TiN(A). (b) TiN(C). (Sample preparation: TiN/TiO x was formed, and then TiN was selectively removed.) The schematic diagram for the high concentration of oxygen vacancy formation in TiO x using Ti rich TiN. WF and $R_{\text{s}}$ as a function of Ti/N ratio. The initial resistance of TiN(A), TiN(B) and TiN(C) at (a) 0.2 and (b) $-0.2$ V. DC $I$--$V$ switching results for various TE electrodes. (a) TiN(A), (b) TiN(B), (c) TiN(C), and (d) Ti. Summary of on/off current ratio and $\mathit{Kw}$ for TiN(A), TiN(B), and TiN(C). $\mathit{Kw}$ was measured after fifth cycling. Set voltage at fifth cycle of switching for TiN(A), TiN(B), TiN(C), and Ti. Cumulative graph of HRS and LRS current for TiN(A) and TiN(C) resistor stacks. The current values were measured at 0.7 V. Schematic band diagram of (a) TiN(A) and (b) TiN(C) stack in LRS. Transition from direct tunneling to FN tunneling with voltage. Switching mechanism of TiO x /Ta 2 O 5 stacks, combination of filament and interface. DC sweep switching endurance characteristics.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.52.04CD05