Fabrication and Memory Effect of Zr Nanocrystals Embedded in ZrO2 Dielectric Layer

概要

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A floating gate (FG) memory structure employing Zr nanocrystals (NCs) embedded in a ZrO2 dielectric layer was fabricated for the first time through a one-step process using dc-magnetron sputtering deposition. The unique FG memory stacked only with an NC-capping ZrO2 control oxide layer, without a tunneling oxide layer, was obtained under oxygen-deficient conditions during the sputtering process. Transmission electron microscopy (TEM) revealed that crystalline Zr-NCs with sizes ranging from 3 to 8 nm were embedded in the ZrO2 layer with densities of Zr-NC up to $1.22 \times 10^{12}$ cm-2. Capacitance versus voltage ($C$–$V$) curves of a Zr-NC-based metal–oxide–semiconductor (MOS) capacitor were also obtained. The clockwise $C$–$V$ hysteresis loops on the basis of the Zr-NC-based MOS structure fabricated in this work were understood by the electron trapping of Zr–O dangling bonds at the interface between Zr-NCs and the ZrO2 capping layer.
2007-12-25