Effects of plasma treatment on the precipitation of fluorine-doped silicon oxide

Precipitates were observed on the surface of fluorine-doped silicon oxide (SiOF) films. These precipitates are flake-type and hexagonal in shape, showing up rapidly after initiation, and clustered at the wafer center. Post-deposition N2O plasma treatment (post-plasma treatment) was found to be most effective in inhibiting the appearance of precipitates. In this paper, effects of post-deposition N2O plasma treatment on the suppression of precipitates and stabilities of SiOF film were studied. X-ray photoelectron spectroscopy (XPS) analyses were conducted to investigate the changes in surface composition of SiOF films after N2O plasma treatment. The surface morphology of the film was characterized by atomic force microscopy (AFM). Cross-sectional transmission electron microscopy (TEM) images showed that a surface layer of 150 Å was generated after N2O plasma treatment. The changes on surface structures of SiOF films caused by N2O plasma treatment and the consequent inhibition of precipitate formation were discussed.