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

Abstract

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.