FDTD modeling of finite spot scatterometry

In this work, the FDTD method is applied to the modeling of finite spot scatterometry. Scatterometry is a non-imaging optical technique for extraction of parameters characterizing the quality of wafer processing in the IC industry. Several numerical methods have previously been adapted for scatterometry applications. However, infinite spot assumption has been inherent there. A Gaussian beam approach will be presented now as an alternative. It allows investigating the influence of reduced spot size on the accuracy of scatterometry techniques, with simultaneous economies in terms of wafer surface.