Characterization of hafnium aluminate gate dielectrics deposited by liquid injection metalorganic chemical vapor deposition

Thin films of hafnium aluminate, with varying aluminum content, have been deposited by liquid injection metalorganic chemical vapor deposition using the metal alkoxide precursors hafnium methyl-methoxy-propanolate and aluminum iso-propoxide. X-ray diffraction analysis showed that the films were amorphous at aluminum concentrations above 7 at. %. Postdeposition annealing indicated that the oxide-transition temperature from amorphous to crystalline increased with aluminum content. Medium-energy ion scattering showed that up to 900 °C, internal oxidation of the silicon substrate had been inhibited. The capacitance–voltage characteristics of the films significantly improved following annealing in dry air