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

Precursors of formula [Ce(hfac) 3 {MeO(CH 2 CH 2 O) n Me}], 1 ( n = 1), 2 ( n = 2), and 3 ( n = 3), and [{Ce(hfac) 3 } 2 {μ-MeO(CH 2 CH 2 O) 4 Me}], 4 (hfac = CF 3 COCHCOCF 3 ), 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 Ce 4 O 7, 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(CH 2 CH 2 O) 2 Me}] gave films of the mixed Ce(IV)Y(III) oxide Ce 2 Y 2 O 7 . 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 CeO 2 . 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.