Thickness and refractive index measurement of a wafer based on the optical comb

We suggested and demonstrated a novel method that can determine the thickness and refractive index of a wafer at the same time in a single measurement by using the optical comb. The thickness and refractive index of a wafer can be separated simply from optical thickness by using the various phase information obtained in spectral domain. For the feasibility test, the thickness and refractive index of a double side polished wafer were measured.