Polarized Bidirectional Reflectance Distribution Function for Optical Substrate and Different Films

Laser light scattering is a powerful tool for its noncontract nature and its convenience to nondestructive examination in the semiconductor industry. In order to detect the quality of the substrate and coated optical elements effectively, firstorder vector perturbation microfacet polarized light scattering model is established by microfacet theory and the polarized bidirectional reflectance distribution function (PBRDF) is derived. PBRDF describes both the scattering characteristics and the polarization characteristics of optical substrate. The scattering field is certain with a given microroughness optical substrate. Therefore, the optical information can be inversed by the study of scattering field. The numerical value simulates and analyzes the influence of the thickness of SiO2 and TiO2 films on the PBRDF, at interfaces roughness perfectly correlated and completely uncorrelated model, respectively. The results show that the PBRDF is coincident little by little at interfaces roughness perfectly correlated and completely uncorrelated model with the increment of thickness of SiO2 films. And film can perfectly replicate surface profile of substrate at this time. With the increment of thickness of TiO2 films, the PBRDF becomes larger and larger, which illustrated that TiO2 film has smoothing effect on the roughness of the substrate. The optical information of the substrate can be measured by calculating the PBRDF of different films, which provides theoretical basis for quality evaluation and identify the information of contaminants detected in the semiconductor industry.