Characteristics of oxide thin films from carboxylate precursors

Oxide thin films on Si substrates were prepared from carboxylate precursors by the reaction of the metal nitrates and ammonium trimethylacetate. Precursor salts were characterized with respect to purity, structure, thermal pyrolysis, and phase development during calcination. A solvent system, based on carboxylic acid/amine mixture, was developed to dissolve the synthesized precursors, resulting in increased solubility, viscosity, and stability. Smooth, fine-grained ZrO2, Y2O3, and YSZ films were obtained on Si wafers by spin-coating and subsequent heat treatment above 500 C. Films heat treated below 700 C were generally adherent, amorphous, or microcrystalline, while YSZ and ZrO2 showed (111) preferred orientation above 700 C. These oxide films show promise as protective or buffer layers on Si wafers.