title: Atomic layer deposition, characterization, and growth mechanistic studies of TiO2 thin films.
abstract: Two heteroleptic titanium precursors were investigated for the atomic layer deposition (ALD) of titanium dioxide using ozone as the oxygen source. The precursors, titanium (N,N'-diisopropylacetamidinate)tris(isopropoxide) (Ti(O(i)Pr)3(N(i)Pr-Me-amd)) and titanium bis(dimethylamide)bis(isopropoxide) (Ti(NMe2)2(O(i)Pr)2), exhibit self-limiting growth behavior up to a maximum temperature of 325 °C. Ti(NMe2)2(O(i)Pr)2 displays an excellent growth rate of 0.9 Å/cycle at 325 °C while the growth rate of Ti(O(i)Pr)3(N(i)Pr-Me-amd) is 0.3 Å/cycle at the same temperature. In the temperature range of 275-325 °C, both precursors deposit titanium dioxide in the anatase phase. In the case of Ti(NMe2)2(O(i)Pr)2, high-temperature X-ray diffraction (HTXRD) studies reveal a thickness-dependent phase change from anatase to rutile at 875-975 °C. X-ray photoelectron spectroscopy (XPS) indicates that the films have high purity and are close to the stoichiometric composition. Reaction mechanisms taking place during the ALD process were studied in situ with quadrupole mass spectrometry (QMS) and quartz crystal microbalance (QCM).
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Kaipio
authors.forename: Timothee
authors.initials: T
authors.lastname: Blanquart
authors.forename: Yoann
authors.initials: Y
authors.lastname: Tomczak
authors.forename: Jaakko
authors.initials: J
authors.lastname: Niinistö
authors.forename: Marco
authors.initials: M
authors.lastname: Gavagnin
authors.forename: Valentino
authors.initials: V
authors.lastname: Longo
authors.forename: Heinz D
authors.initials: HD
authors.lastname: Wanzenböck
authors.forename: Venkateswara R
authors.initials: VR
authors.lastname: Pallem
authors.forename: Christian
authors.initials: C
authors.lastname: Dussarrat
authors.forename: Esa
authors.initials: E
authors.lastname: Puukilainen
authors.forename: Mikko
authors.initials: M
authors.lastname: Ritala
authors.forename: Markku
authors.initials: M
authors.lastname: Leskelä