Chemical Vapor Deposition of Cerium Oxide Using the Precursors [Ce(hfac)3(glyme)]

Precursors of formula [Ce(hfac)3{MeO(CH2CH2O) n Me}], 1 (n = 1), 2 (n = 2), and 3 (n = 3), and [{Ce(hfac)3}2{μ-MeO(CH2CH2O)4Me}], 4 (hfac = CF3COCHCOCF3), have been prepared and used as precursors for chemical vapor deposition (CVD) of films of cerium oxides on the substrates Si, Pt, and TiN. Thermal CVD at 450 °C with oxygen as carrier gas gave mixed Ce(III)/Ce(IV) oxides, and the main crystalline component was Ce4O7, but with fluoride impurity. The fluoride impurity was not observed if CVD was carried out using moist oxygen as carrier gas or if the as-deposited films were annealed in oxygen. Codeposition with [Y(hfac)3{MeO(CH2CH2O)2Me}] gave films of the mixed Ce(IV)Y(III) oxide Ce2Y2O7. The depositions of cerium oxides could be enhanced by use of a palladium precursor catalyst [Pd(2-methylallyl)(acetylacetonate)] and could then be carried out at 250 °C, giving films of CeO2. Under carefully controlled conditions, films of ceria-supported palladium could be prepared by this method. The films were characterized by using X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction techniques.