Densification of chemical vapor deposition silicon dioxide film using oxygen radical oxidation

Silicon dioxide (SiO2) films formed by chemical vapor deposition (CVD) were treated with oxygen radical oxidation using Ar/O2 plasma excited by microwave. The mass density depth profiles, carrier trap densities, and current-voltage characteristics of the radical-oxidized CVD-SiO2 films were investigated. The mass density depth profiles were estimated with x ray reflectivity measurement using synchrotron radiation of SPring-8. The carrier trap densities were estimated with x ray photoelectron spectroscopy time-dependent measurement. The mass densities of the radical-oxidized CVD-SiO2 films were increased near the SiO2 surface. The densities of the carrier trap centers in these films were decreased. The leakage currents of the metal-oxide-semiconductor capacitors fabricated by using these films were reduced. It is probable that the insulation properties of the CVD-SiO2 film are improved by the increase in the mass density and the decrease in the carrier trap density caused by the restoration of the Si-O network with the radical oxidation.