Ivan Ohlídal, Daniel Franta, Miloslav Ohlídal, Karel Navrátil
Determination of thicknesses and spectral dependences of refractive indices of non-absorbing and weakly absorbing thin films using the wavelengths related to extrema in spectral reflectances
Vacuum 61 (2001) 285–289
In this contribution a new efficient modification of the method enabling us to perform the optical characterization of non-absorbing and weakly absorbing thin films without using the absolute values of the reflectances measured will be presented. Namely, this modification is based on determining the values of the wavelengths corresponding to the points of touching the spectral dependences of the reflectances of the studied films measured for several angles of incidence with the envelopes of maxima and minima of these spectral dependences. By means of combining the explicit formulae containing the wavelengths mentioned and the suitable iteration procedure one can evaluate the values of the thicknesses and spectral dependences of the refractive indices of the films analyzed in both reliable and precise ways. This fact will be demonstrated through the optical characterization of non-absorbing films of silicon dioxide and weakly absorbing films of photoresist placed on silicon single crystal substrates. The results of this characterization will be compared with those achieved using a combined method of variable angle of incidence spectroscopic ellipsometry and near normal incidence spectroscopic reflectometry.
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