Ellipsometry on very thick multilayer structures

Abstract

We present a method that allows detailed analysis of complicated spectral ellipsometry spectra, such as those of thick (≈10 μm) multilayer structures found in modern integrated optics devices. Ellipsometry should be the natural choice for thorough nondestructive characterisation of those heterostructures, but extraction of the required parameters is often impracticable by common approaches. Our method is based on spline parametrisations of the unknown optical functions and is applicable to materials either with a smooth optical response or displaying sharp electronic transitions in the analysed energy range. We illustrate the method with results obtained on thick waveguide structures used for chemical sensors.