Optical properties determination of Fully Depleted Silicon On Insulator (FDSOI) substrates by ellipsometry

We present an original experimental approach developed to extract with a good level of accuracy and confidence the optical properties of SOI layers for several thicknesses ranging from 3nm up to 12nm. The measurements were done using a spectroscopic ellipsometer in conjunction with an x-ray reflectometer. The instrumental function of the ellipsometer was first characterized experimentally to minimize systematic errors. A specific experimental protocol was then used to produce SOI Silicon layers and extract their optical properties. The resulting dispersion models were tested on other sample structures to check the validity of the models.