Conduction mechanisms and an evidence for phonon-assisted conduction process in thin high-k HfxTiySizO films
Abstract Electrical behavior of high-k Hf x Ti y Si z O layers with different Hf:Ti ratios in the film have been investigated. The films are prepared by MOCVD using novel single-source precursors chemistry. Oxide and interface charges, leakage currents and conduction mechanisms are found to be a strong function of the film composition. The films with lower Hf content show lower level of oxide and interface charges and higher dielectric constant whereas those with higher Hf content have better leakage current properties. It is established that in the films with lower Hf content the conduction is governed by a phonon-assisted process. The change of the conduction mechanism from Poole–Frenkel emission to phonon-assisted tunneling is assigned to possible structural changes which take place when changing the composition of the films.
Electrical characterization of zirconium silicate films obtained from novel MOCVD precursors
In the present work, the potential of zirconium silicate (ZrSixOy) films as an alternative gate dielectric to SiO2 for future technology generations is demonstrated. Novel single-source precursors for MOCVD of zirconium silicate were synthesized and ZrSixOy layers were deposited. I–V and C–V measurement data are presented and detected charge trapping phenomena are discussed.
(Ta2O5)(1-x)(TiO2)(x) deposited by photo-induced CVD using 222 nm excimer lamps
Abstract We report the deposition of thin (Ta2O5)1−x(TiO2)x films on quartz and crystalline p-type Si (1 0 0) by photo-induced CVD using 222 nm excimer lamps at temperatures from 50 to 350 °C. The alkoxide precursors titanium isopropoxide and tantalum tetraethoxy dimethylamenoethoxide were mixed in various ratios, vaporised, and then driven into the reaction chamber by an Ar carrier gas, where they were exposed to the UV radiation. Films greater than 500 nm in thickness were grown at a pressure of several millibars and at a deposition rate of approximately 60 nm/min at 350 °C. The chemical bonding of the films has been analysed by Fourier transform infrared spectroscopy, and indicated that both Ta2O5 and TiO2 stretching absorption peaks were present. The optical properties of the layers were analysed by UV–Vis spectroscopy between wavelengths of 195–1100 nm. Band gap energies ranging between 3.2 and 4.2 eV were obtained for films of various compositions.