Characterization and production metrology of gate dielectric films

摘要

We report efforts to develop optical dispersion models for new high k materials and silicon oxynitrides. We find the Tauc-Lorentz model provides superior fits to Ta_2O_5 and ZrO_2 dielectric films in the spectral range 1.5-6.0 eV. However, for typical oxynitrides which do not absorb below ～6.0 eV, we find the Tauc-Lorentz model confers no advantage over models which do not account for absorption. For the oxynitrides, we also find a monotonic relationship between film refractive index and nitrogen concentration, potentially useful for gate dielectric process control.