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 Al2 O3 films in a metal/ Al2 O3 [TiN Al2 O3] Si O2 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 Al2 O3 films after subsequent annealing treatment. The TiN nanocrystals with a high density of >1× 1012 cm2 and a small size of <3 nm have been observed. A large hysteresis memory window of ∼4.3 V at small sweeping gate voltage of 3 V has been observed as compared with a pure Al2 O3 charge trapping layer, due to highly charge confinement in the TiN metal nanocrystals. The hysteresis memory window of 1.4 V has also been observed under an extremely small sweeping gate voltage of 1 V. A large memory window of ∼3.9 V is observed after 10 years 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. © 2007 American Institute of Physics.