Fluorine content of SiOF films as determined by IR spectroscopy and resonant nuclear reaction analysis

Abstract

In this article, the authors compare the fluorine concentrations obtained from the strength of the infrared-absorption band due to Si–F bonds, with the absolute concentrations determined from F19(p,αγ)O16 resonant nuclear reaction analysis, for a series of fluorinated silicon oxide (SiOF) films prepared by remote plasma-enhanced chemical-vapor deposition with different flow rates of H2 in SiF4∕O2∕He mixtures. The authors use this comparison to calibrate the proportionality constant between the strength (integrated absorption) of the infrared-absorption band due to Si–F bonds and the concentration of these bonds in the films. The authors found that (under the Gentzel and Martin approach [Surf. Sci. 34, 33 (1973)]) this calibration requires the correction of the “fudge” factor, to a new value, γ=1.28, which is more consistent with the small correction to the local field expected for porous SiOF films. The authors also found that the changes in the refractive index and density of the films introduce less significant corrections in the quantification process of fluorine by the infrared method.