The optical measurement on the CVD silica film deposited on a fused quartz substrate

We develop a completed mathematical method to calculate the optical constants of the single layer thin film grown on a transparent substrate. The reflectance and transmittance were first measured individually from the substrate and workpiece by the spectrometer. The workpiece consists of the interested film and substrate. The spectrometer is selected because this instrument is affordable and easily installed in most labs. The measured reflectance was corrected by background signal subtraction. A developed code based on the matrix method and two-dimensional Newton-Raphson iteration was used to extract the optical constants from the reflectance and transmittance measurements on the workpiece. The thin film thickness can be obtained from the graphic method when the measured wavelength ranges were properly selected. The refraction index of the quartz substrate decreases with increasing the measured wavelengths ranged from visible to near infrared spectrum. This data trend is consistent with the data reported in the documents. The refraction index of the CVD grown silica is slightly higher than that of the quartz substrate.