Modified reflectance-transmittance method for the metrology of thin film optical properties

Abstract

Because the surface roughness of a thin film will cause light scattering, the reflectance (R) and transmittance (T) measured using a UV/visible (vis) spectrometer become lower than the actual values. The deviation becomes larger with increasing roughness and decreasing wavelength of incident light. Hence, it is necessary to correct measured R and T using roughness as a modification factor. The refraction (n) and extinction coefficient (k) obtained by the modified R-T method are closer to those results obtained using a variable angle spectroscopic ellipsometer (VASE), which provides more precise results than a n and k analyzer.