For the surface shape measurement of a semiconductor with a highly reflective index, it is important to effectively suppress the harmonic signals from multiple reflections. In application, the phase extraction algorithm should have a maximum value when there is no phase-shift miscalibration. In this presentation, a new 4N - 3 phase extraction algorithm, which has the ability to suppress harmonic signals and exhibits a fringe contrast maximum value when there is no phaseshift error, was derived. This new 4N - 3 algorithm consists of a new polynomial window function and a discrete Fourier transform term and has the ability to compensate for 2^nd-order nonlinearity in the phase shift. The suppression ability of the new polynomial window function is compared with other conventional window functions. The sampling functions of the new 4N - 3 algorithm have much smaller amplitudes in the vicinity of the detection frequency than does synchronous detection or other phase extraction algorithms with conventional window functions.

Date Published: 18 August 2014
PDF: 6 pages
Proc. SPIE 9203, Interferometry XVII: Techniques and Analysis, 92030Q (18 August 2014); doi: 10.1117/12.2061476

Published in SPIE Proceedings Vol. 9203:
Interferometry XVII: Techniques and Analysis
Katherine Creath; Jan Burke; Joanna Schmit, Editor(s)