Formation and composition of titanium oxinitride nanocrystals synthesized via nitridizing titanium oxide for nonvolatile memory applications

Formation and composition analyses of titanium oxinitride nanocrystals (NCs) fabricated via treating a magnetron co-sputtered thin film of titanium and silicon dioxide with a rapid thermal annealing in nitrogen ambient were demonstrated for nonvolatile memory applications. Phase separation characteristics with different annealing conditions were examined by transmission electron microscopy and chemical bonding characteristics were confirmed by X-ray photon emission spectra. It was observed that a blanket layer composed mainly of titanium oxide was still present as annealing temperature was increased to 700 °C, associated with the thermodynamically stable phase of titanium oxide. Furthermore, a higher thermal treatment of 900 °C induced formation of a well-separated NC structure and caused simultaneously partial nitridation of the titanium oxide, thereby forming titanium oxinitride NCs. A significant capacitance–voltage hysteresis in threshold voltage shift at 1 V was easily achieved under a small sweeping voltage range of + 2 V/−2 V, and a memory window retention of 2.2 V was obtained after 107 s by extrapolation under a 1 s initial-program/erase condition of + 5 V/−5 V, respectively.