A study of the dielectric characteristics of aluminum oxide thin films deposited by spray pyrolysis from Al(acac) 3

Abstract

The dielectric characteristics of aluminum oxide thin films deposited by the spray pyrolysis technique are reported. The films were deposited with different molarities from a spraying solution of aluminum acetylacetonate and N, N-dimethylformamide. The films were deposited on silicon substrates at temperatures ranging from 450 to 650°C. The addition of water mist during the deposition process led to a remarkable improvement of the overall characteristics of the films. Films with excellent dielectric characteristics and low surface roughness were obtained. The results of the characterization indicate that there is a significant presence of carbon in the films. This carbon in the films modifies the electrical conduction characteristics leading to behavior similar to that displayed by off-stoichiometric silicon oxide (SiO 2) films. It is observed that the overall resistivity of the film decreases when both the molarity of the solution and the deposition temperature increase. This behavior correlates with the increase in the amount of carbon remaining inside the film. The films as deposited have a surface state density in the range of 10 11 1/eV-cm 2 and are able to stand electric fields higher than 5 MV/cm without observing dielectric breakdown.