<I>In-Situ</I> Ellipsometric Analysis of the Formation Process of Ta<SUB>2</SUB>O<SUB>5</SUB> Thin Films in MOCVD

The formation process of Ta2O5 films in MOCVD using Pentaethoxy tantalum (PET) as the metal organic source and O2 as the reactant gas has been analyzed by in-situ ellipsometry at deposition temperatures of 473-773 K. According to the change in the growth rate of the films, the formation process can be devided into three stages, that is, the initial stage, the transition stage and the final stage. The growth rate and the optical constant of the films were found to depend on the type of substrate, the deposition temperature, and the deposition time. The corrosion resistance of the films also depends on substrate temperatures. The films formed at 673 K had the highest corrosion resistance in HCl and HF solutions. These films also showed a very high value of resistivity such as 1.5×1011 Ω·m at 10 mHz. All films obtained at temperatures of 473-773 K had amorphous structures.