Effects of precursors and substrate materials on microstructure, dielectric properties, and step coverage of (Ba, Sr)TiO3 films grown by metalorganicchemical vapor deposition

(Ba, Sr)TiO3 (BST) thin films have been grown on planar Ir/Si and Pt/Si sub strates and on three-dimensional (3D) Ir electrodes by metalorganic chemica l vapor deposition using two kinds of beta-diketonate-based BST precursors. Film growth was studied as a function of film thickness, composition, and substrate temperature. Growth rate was monitored by in situ spectroscopic e llipsometry. The BST films were characterized ex situ by a variety of techn iques including x-ray photoelectron spectroscopy, Auger electron microscopy , atomic force microscopy, transmission and scanning electron microscopy, x -ray diffraction, and impedance analyzer. The results reveal that the two s ets of BST precursors, albeit slightly different, show quite different reac tivities that strongly affect the step coverage on the 3D structure. Howeve r, different reactivities have no apparent effect on the microstructure, su rface morphology, and dielectric properties of the stoichiometric BST films . These properties strongly depend on the film composition, substrate mater ial, and growth temperature. In general, the BST films grown on Pt exhibit better crystalline quality, surface smoothness, and dielectric properties c ompared to those grown on Ir under the optimal growth conditions. (C) 2000 American Institute of Physics. [S0021- 8979(00)01001-X].