Maximum thickness determinable by imaging ellipsometry

Abstract As a hybrid of single-point measurement ellipsometry and optical microscopy, imaging ellipsometry possesses capability to characterize optical constants and/or thickness distribution of sample surfaces. For single-point measurement spectroscopic ellipsometry, the preferred limit of the film thickness is less than 5 μm. The thicker the film, the longer the required probe wavelength. In this note, the maximum thickness that imaging ellipsometry can determine was analyzed in terms of the measurement area and the refractive index of the thin film. This thickness criterion will be helpful to estimate the ability of imaging ellipsometry with high spatial resolution to evaluate a thin film thickness.