Controlled index of refraction silicon oxynitride films characterized by variable angle spectroscopic ellipsometry

Yi Ming Xiong, Paul G. Snyder, John A. Woollam, G. A. Al-Jumaily, F. J. Gagliardi, Eric R. Krosche

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Silicon oxynitride (SiOxNy) films were deposited on silicon substrates by ion-assisted deposition (IAD) and low pressure chemical vapor deposition (LPCVD). Variable angle spectroscopic ellipsometry (VASE) was used to characterize the deposited films optically over the 320-820 nm spectral range. The measured VASE spectra were analyzed using the Bruggeman effective medium approximation (EMA) by modeling the SiOxNy films to be physical mixtures of two distinct phases, SiO2 and Si3N4. Although SiOxNy is actually a chemical mixture, we show that the EMA model can be employed successfully to describe its optical properties. As a result, the layer thickness and composition, as well as the refractive index spectrum, of each film were determined. It was found that the optical properties can be accurately and reproducibly varied by controlling the ratio of oxygen to nitrogen in the film. The very good fits between the measured and calculated VASE spectra, for all the samples, indicate that the adopted EMA model is a good approximation for characterizing the optical response of both IAD and LPCVD deposited SiOxNy films.

Original languageEnglish (US)
Pages (from-to)248-253
Number of pages6
JournalThin Solid Films
Issue number1-2
StatePublished - Dec 10 1991

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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