Optical, structural and electrical characteristics of aluminum oxynitride thin films deposited in an Ar-N gas mixture RF-sputtering system

摘要

The optical, structural and electrical characteristics of aluminum oxynitride thin films deposited on silicon by rf-sputtering under a fixed oxygen flow and two different Ar and N gas flows are reported. The stoichiometry of the films was studied by EDS as a function of the deposition parameters. In general, the relative oxygen content within the films was higher for a high N/Ar (5/1) gas flow ratio, these films presented refractive indexes in the range of 1.5-2.0, with deposition rates close to 4.0 nm/min, and surface roughness of approximately 13 A. Films deposited with a low N/Ar (1/5) flow ratio presented refractive indexes in the range of 1.7 to 2.0, deposition rates of 7 nm/min and surface roughness of 26 A. IR spectroscopy measurements on these films presented an absorption band spreading from 500 to 900 cm~(-1). The width and peak of this band depends on the rf power and correlates with the oxygen content in the films. Films with the best electrical characteristics present an average dielectric constant of 7.2 and 8.7 standing electric fields up to 4.5 and 2 MV/cm without observing destructive dielectric breakdown for high and low N/Ar gas ratios respectively.