White-light spectral interferometric technique to measure a nonlinear phase function of a thin-film structure
نویسنده
چکیده
We present a new two-step white-light spectral interferometric technique to measure a nonlinear phase function of a thin-film structure. The technique is based on recording of channeled spectra at the output of a Michelson interferometer and their processing by using a windowed Fourier transform to retrieve the phase functions. First, the phase function including the effect of a thin-film structure is retrieved. Second, the structure is replaced by a reference sample of known phase change on reflection and the corresponding phase function is retrieved. From the two functions, the nonlinear phase function of the thin-film structure is obtained. The feasibility of this simple method is confirmed in processing the experimental data for a SiO2 thin film on a Si wafer of known optical constants. Four samples of the thin film are used and their thicknesses are determined. The thicknesses obtained are compared with those resulting from reflectometric measurements, and good agreement is confirmed.
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