Physical and electrical characteristics of atomic layer deposited TiN nanocrystal memory capacitors

The physical and electrical characteristics of atomic layer deposited TiN nanocrystals embedded in high-$k$ $Al2O3$ films in a metal/$Al2O3∕[TiN∕Al2O3]∕SiO2∕p-Si$ structure have been investigated. High-resolution transmission electron microscopy and x-ray photoelectron spectroscopy show the formation of tiny TiN nanocrystals embedded in $Al2O3$ films after subsequent annealing treatment. The TiN nanocrystals with a high density of $>1×1012∕cm2$ and a small size of $<3nm$ have been observed. A large hysteresis memory window of $∼4.3V$ at small sweeping gate voltage of $3V$ has been observed as compared with a pure $Al2O3$ charge trapping layer, due to highly charge confinement in the TiN metal nanocrystals. The hysteresis memory window of $1.4V$ has also been observed under an extremely small sweeping gate voltage of $1V$⁠. A large memory window of $∼3.9V$ is observed after $10years$ of retention. A maximum hysteresis memory window is limited by both of the nanocrystal density and leakage current at a high temperature annealing treatment of the TiN nanocrystal memory capacitors.