Composition, structural, and electrical properties of fluorinated silicon-nitride thin films grown by remote plasma-enhanced chemical-vapor deposition from SiF4/NH3 mixtures

Fluorinated silicon-nitride films (SiNx:F) have been prepared at 250 deg. C by remote plasma-enhanced chemical-vapor deposition using mixtures of SiF4/NH3 in different proportions. The structure, relative composition, and fluorine content of the films were evaluated by Fourier-transform infrared spectroscopy, Rutherford backscattering, ellipsometry, and resonant nuclear-reaction analysis. The electrical properties of the films were also assessed from the current-voltage characteristics of Al-SiNx:F-Si metal-insulating-semiconductor structures. It was found that the SiF4/NH3 ratio produces little influence on the refractive index and density of the films, but this ratio has important effects on the fluorine content, deposition rate, and electrical properties. In general, these SiNx:F films are free of Si-H bonds, chemically stable, and show breakdown fields above 8 MV/cm