Nonvolatile Memory With TiN Nanocrystals Three-Dimensionally Embedded in $\hbox {Si}_{3}\hbox {N}_{4}$ Formed by Spinodal Phase Segregation

In this letter, TiN nanocrystals three-dimensionally embedded in the Si₃N₄ formed by spinodal phase segregation was investigated as the discrete charge-trapping layer in a metal-oxide-nitride-oxide-silicon structure for nonvolatile-memory applications. TiN-nanocrystal formation was verified by X-ray diffraction analysis while the 3-D distribution of nanocrystals in the Si₃N₄ film was confirmed by transmission electron microscopy with the average size of 5.1 nm and a density of 9.8 × 10¹¹cm^-2. The promising memory performance was evidenced by the large memory window of 1.81 V with plusmn4-V program/erase voltage, the high operation speed of 1.52-V threshold-voltage shift by programming at +4 V for 10 ms, the negligible memory-window degradation up to 10⁵ operation cycles, and 11% charge loss after ten-year operation. Most importantly, the charge-storage structure can be formed by a cosputtering approach which is simple and fully compatible with existent ultralarge scale integration technology.