Snapshot angle-resolved channeled spectroscopic micro-ellipsometry for thin-film characterization

We present an angle-resolved channeled spectroscopic micro-ellipsometry (ACSE) system operating in a near-normal-incidence configuration with a line-scan spectrometer. The hardware covers the visible spectral range from 480 to 680 nm and provides incidence angles from 0° to 60°. By analyzing the spectral interference envelope, we accurately separate and extract the low-frequency (DC) and high-frequency (AC) components of the interferometric signal, corresponding to the baseline intensity and modulation, respectively. Moreover, we employ a Hilbert transform to analyze and calibrate spectral amplitude and phase errors, thereby improving the precision of the retrieved ellipsometric parameters. To validate the proposed method, we measured SiO₂ thin films deposited on a Si wafer with thicknesses spanning from 10 to 1500 nm and successfully determined both thickness and refractive index values, which were confirmed by comparing them with those obtained using a commercial ellipsometer.