Korean Journal of Chemical Engineering, Vol.21, No.1, 286-291, January, 2004
Thermodynamic Analysis of Liquid Source Chemical Vapor Deposition Process for the Preparation of a Ba-Sr-Ti Oxide Film
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The equilibrium concentrations of the chemical species in a Ba-Sr-Ti-C-H-O system, corresponding to a liquid source chemical vapor deposition (LSCVD) process used in the preparation of barium strontium titanium oxide (BST) films, were determined by thermodynamic calculations. Ba(dipivaloylmethanato)2, Sr(dipivaloylmethanato)2, and Ti(tetra-isopropoxide) were assumed as the metal sources, and tetrahydrofuran (THF) and O2 as the solvent and oxidant, respectively. An increase in the amounts of THF, a major source of graphite production, significantly increases the equilibrium concentrations of metal oxides and carbonates in the system. On the other hand, an increase in the O2 content decreases the graphite content and increases the amount of carbonates. Based on these results, the conditions for an LSCVD process that produces minimum amounts of carbon impurities in a BST film were identified as a function of the process temperature and the O2/THF ratio. The results of the equilibrium calculations are in reasonable agreement with experimental data, which indicates that the results can be used as a basis for identifying LSCVD conditions needed to prepare BST films with defined compositions.
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