Angular scattering and ellipsometry of the scattered field: multiscale roughness and contamination of surfaces

Light scattering is well known to be dependent on the optical properties and surface roughness or bulk inhomogeneities of components. Angular scattering measurements and the development of electromagnetic theories at Institut Fresnel Marseilles permit to quantify the roughness behaviour. Measurements can be performed at different wavelengths from the UV to the near IR to access to different scales of characterization. Atomic Force Microscopy is used to complete these measurements at the microscopic scale, and predict the surface behaviour in the X rays domain. All these techniques rise to a multiscale characterization of all surfaces, which reveals in most cases fractal behaviours. The scatterometer has been extended and allows to perform ellipsometric measurements on scattered light in each direction of space. Results can be investigated by electromagnetic theories. They permit to directly separate bulk and surface effects in the case of bare substrates and reveal the high sensitivity of the polarimetric phase difference to the presence of contaminants on surfaces, even in the case of first order contaminants, that is to say whose size is in the same order as the substrate roughness.