Analysis of Line-Edge Roughness Using EUV Scatterometry

Smaller and more complex three-dimensional periodic nanostructures are part of the next generation of integrated electronic circuits. Additionally, decreasing the dimensions of nanostructures increases the effect of line-edge roughness on the performance of the nanostructures. Efficient methods for characterizing three-dimensional nanostructures are required for process control. Here, extreme-ultraviolet (EUV) scatterometry is exploited for the analysis of line-edge roughness from periodic nanostructures. In line with previous observations, differences are observed between line edge and line width roughness. The angular distribution of the diffuse scattering is an interplay of the line shape, the height of the structure, the roughness along the line, and the correlation between the lines. Unfortunately, existing theoretical methods for characterizing nanostructures using scatterometry do not cover all these aspects. Examples are shown here and the demands for future development of theoretical approaches for computing the angular distribution of the scattered X-rays are discussed.