Determination of optical constants and stoichiometry of BxOyNz films deposited by ECR-PVD

Boron oxynitride (BON) films have been deposited on Si(100) substrates by electron cyclotron resonance plasma-assisted physical vapor deposition technique (ECR-PVD), and their optical properties have been studied. The thickness, index of refraction, and absorption coefficient of as-grown and annealed films were obtained by variable angle spectroscopic ellipsometry (SE). Excellent fitting of the measured SE data was accomplished using typical parameterized oscillator functions to obtain Kramers–Kronig consistent optical parameters of the BON layers. BON samples grown with boron evaporation rates below 0.2 Å/s were successfully characterized as single layers for their optical response up to 5.66 eV. Auger electron spectrometry (AES) measurement performed on a series of samples shows boron rich BON films with an average elemental composition of B0.73N0.15 O0.12. The films were also found amorphous based on both SE and X-ray diffraction measurement results. The optical constants of the annealed films indicated some variation to some extent. However, no features appeared in the ellipsometric data that would indicate a phase change in crystallinity.