PECVD Grown SiO2 Film Process Optimization

SiO₂ films have been widely applied in the production of electronic devices, integrated devices, optical thin film devices, sensors because of their desirable properties, such as good insulation, high light transmittance, strong corrosion resistance, good dielectric properties, etc. Amorphous silicon dioxide was fabricated by plasma enhanced chemical deposition on GaAs substrate. The thickness and refractive index are obtained by optical transmittance of the film, which are measured by ellipsometer. The deposition rate of the film and the refractive index are studied at different time, pressure, and the ratio of SiH₄/N₂O. The SiO₂ thin film growth rate remained basically unchanged versus time. The reaction chamber pressure, which make the SiO₂ thin film growth rate getting the peak, should be about 105Pa. But the SiO₂ thin film growth rate and the refractive index are anti-related. The enormous changes of the gas flow rate do not have huge impact to the response rate. However, the refractive index of SiO₂ thin film changed greatly when the SiH₄ flow increased the refractive index of the thin films is highest when the ratio of SiH₄/N₂O is 200:20.