Precise interferometric surface profiling of silicon wafer using sampling window and wavelength tuning

Abstract

Phase-shifting fringe analysis using wavelength tuning has been widely applied to interferometric surface measurements of optical flats. However, when measuring the silicon wafer that has the highly reflective surface, the correlated error between the second harmonic component and phase-shift miscalibration can be a significant error in the phase distribution. In this study, a novel design method to derive a phase-extraction algorithm is proposed for the suppression of the correlated error. A new 11-frame algorithm was developed using the Blackman sampling window. The 11-frame algorithm was visualized on the frequency space and complex plane, and its compensation capability was confirmed by numerical error analysis comparing with other algorithms. Finally, the silicon wafer surface was profiled by applying the 11-frame algorithm and Fizeau interferometer.