Application of Bidirectional Ellipsometry to the Characterization of Roughness and Defects in Dielectric Layers
Thomas A. Germer
The polarization of light scattered into directions out of the plane of incidence is calculated for microroughness, defects, or particles in or near a dielectric film on a substrate. The theories for microroughness and Rayleigh scatter in the presence of dielectric films are reviewed, and a method for calculating the scatter from multiple sources is described. The situation of a 1 [mu]m thick layer of SiO2 on silicon illuminated by p-polarized 633 nm light at a 60 degree angle of incidence is used to demonstrate the model calculations. The polarization of scattered light is calculated for scatter from roughness at each of the interfaces separately and roughness of both interfaces when those roughnesses are correlated and uncorrelated. The scatter from a single Rayleigh defect is considered as a function of the position of that defect within the dielectric film, and the scatter from a random distribution of Rayleigh defect is considered as a function of the position of that defect within the dielectric film, and the scatter from a random distribution of Rayleigh defects in the layer is calculated. The capability of distinguishing amongst different scattering sources is evaluated.