In-process measuring procedure for sub-100 nm structures

Fast and nondestructive laser light scattering measurements characterize the quality of surfaces with sub-100 nm structures during the production process. The aim is to detect defective surface structures. The measurement procedure is based on a primary comparison of measured speckle patterns with a multitude of numerically calculated speckle patterns caused by defect-free and defective surface structures. The comparison shows characteristic light scattering effects, which have to be detected by the in-process measurement setup. An efficient rigorous algorithm, implemented on a graphics processing unit, calculates the scattered light intensity distributions within reasonable computing times. The measurements are performed with an angle resolved light scattering measurement setup. The measuring procedure is applied to zinc oxide nanograss surfaces.