Numerical investigations of the influence of different commonly applied approximations in scatterometry

At PTB we investigate the prospects of scatterometric methods for quantitative dimensional metrology of periodic micro- and nanostructures. Commonly applied approximations and simplifications may lead to contributions to the measurement uncertainty or even to systematic measurement errors. Here we present a short overview about the main effects connected with these simplifications. In particular we present numerical investigations of the influence of a finite beam size on the scatterometry results. The results indicate, that an impact of the finite beam size becomes significant only for tightly focused beams with a beam waist radius wo smaller than 10 μm.