Infrared study of AlN films prepared by ion beam deposition. 1. Effects of film thickness, aging, and moisture

Specular reflectance FT-IR spectroscopy was employed to study the changes in the chemical composition of ion beam deposited AlN thin films as a function of film thickness, aging under air and vacuum, and exposure to liquid water. Aluminum nitride films 10, 20, and 40 nm thick were prepared by utilizing a pure aluminum metal target and both pure and 25% hydrogen enriched nitrogen. All films were deposited on gold substrates. It was found that the concentration of the Al-N{sub 2} species present in the AlN films strongly depends on the film thickness and on the gas mixture used for film fabrication. The authors also observed that the AlN films fabricated with pure N{sub 2} plasma are less prone to hydrolysis (when exposed to room air) than are the films prepared with H{sub 2}-N{sub 2} plasma. Prolonged vacuum environment had no significant effect on the spectra of the differently prepared AlN films. Exposure to liquid water promoted hydrolysis equally well in N{sub 2} and H{sub 2}-N{sub 2} fabricated AlN films.