Characterization of fluorine-doped silicon dioxide films by Raman spectroscopy and Electron-spin resonance

Abstract

We have measured Raman and Electron-spin resonance (ESR) spectra of fluorine-doped SiO 2 films deposited by two different methods. In high-density plasma (HDP) films, the Raman band at about 490 cm − 1 becomes drastically stronger as the F/Si ratio increases, whereas the Raman band from threefold ring defect is independent of the F/Si ratio. The unusual increase of the intensity of the 490 cm − 1 band in HDP films has been interpreted in terms of the existence of Si–Si clusters. From a comparison between Raman spectra of HDP film and plasma chemical vapor deposition using tetraethoxysilane (p-TEOS) film with the same F/Si ratios it has been found that HDP film has more Si–Si bonds and threefold ring defects than p-TEOS film. Furthermore, the polarized Raman spectra in the 810 cm − 1 bands indicate that inhomogeneous SiO 2 clusters of various sizes should exist in the network structure of HDP film. The result of the ESR measurement shows that HDP films have fewer dangling bonds than p-TEOS films. It is considered that many Si–Si clusters, threefold ring defects, and inhomogeneous SiO 2 cluster sizes, and the few dangling bonds in HDP films give rise to the film properties of low stress, good adhesion with Si substrate, and low water permeation.