Apparatus and process for performing ellipsometric measurements of surfaces

摘要

A compact ellipsometric apparatus is constructed using as a building block a tri-beam ellipsometric sensor having a monochromatic source of polarized light with a diverging beam of sufficient divergence that three analyzers and associated light detectors may be placed into the beam side by side so that they each receive light reflected from a surface under study at the same angle of reflection. Pairs of these sensors are used together, with one of each pair having in the optical path a quarter wave plate matched to the monochromatic light wavelength and the other of the pair having no quarter wave plate, but with the light wavelength and angle of incidence being the same for each pair. A variety of measurements are made by constructing apparatus using one or more pairs of these basic sensors, the pairs of sensors varying from each other in the light wavelength of the source and the angle of incidence of the polarized beam of light to the surface. Various apparatus having from one to six pairs of sensors have been designed, with higher numbers of sensors providing greater generality in respect to the properties that can be measured.