Structural properties of SiO2 films prepared by plasma-enhanced chemical vapor deposition

SiO2 thin films have been prepared by plasma-enhanced chemical vapor deposition from SIH4 and N2O precursors by using different Values of the N2O/SiH4 flow ratio (gamma). Rutherford backscattering spectrometry has been employed to obtain the O/Si atomic ratio of the films. Infrared spectroscopy has demonstrated that oxides having the same O/Si atomic ratio an characterized by a different structure. Indeed, from the analysis of the Si-O-Si stretching peaks, we have found that the peak frequency and full-width at half-maximum (FWHM) are dependent on gamma. Peak position and FWHM have been used to calculate the bond angle distribution of the films. The results have demonstrated the occurrence of a Si-O-Si bond angle relaxation phenomenon in films deposited by using a larger excess of N2O.