Improvement of silicon oxide film properties by ultraviolet excimer lamp annealing

A novel technology of excimer lamps has been applied to improve the properties of silicon oxide films by VUV photon annealing. Silicon oxide films were deposited at low temperature by ArF laser-CVD in parallel configuration using SiH4 and N2O as precursors. Post-deposition irradiation by VUV photons provided by a Xe excimer lamp (λ = 172 nm) at room temperature and in an inert atmosphere was performed. The films were characterized by Fourier transform infrared spectroscopy (FTIR), single-wavelength ellipsometry and electron spin resonance (ESR) to analyze the changes in the composition, the refractive index and the paramagnetic defects in the film structure. The VUV irradiation time was successively increased until saturation of film properties was reached. As observed by FTIR, the Si-H and Si-O bands show a clear evolution. While the Si-H bonds are broken until reaching their total elimination, an increase in the number of Si-O bonds takes place. These results are in agreement with the ellipsometric measurements in which a decrease in the refractive index towards stoichiometric values (n = 1.46) is observed. Moreover, ESR measurements show an increase in the concentration of paramagnetic defects in the structure by the VUV photon annealing, reaching a lower saturation value in comparison with samples obtained by other deposition methods.