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.