Effect of line roughness on the diffraction intensities in angular resolved scatterometry

Abstract

Scatterometry is a common technique for the characterization of nanostructured surfaces. With shrinking dimensions, fewer and fewer propagating diffraction orders exist, and structure roughness becomes more important. Recent investigations suggest that roughness has to be taken into account for structure reconstruction. The short wavelength of the extreme UV (EUV) is advantageous, since it provides more propagating diffraction orders as compared to UV and visible radiation and increases the sensitivity to small structural features, particularly roughness. We present a method to numerically estimate changes in measured diffraction intensities in angular resolved EUV scatterometry induced by line roughness. The model can be used to include the estimation of the roughness into the structure reconstruction algorithm.