Feature-shape and line-edge roughness measurement of deep submicron lithographic structures using small-angle neutron scattering

We demonstrate the application of small angle neutron scattering (SANS) measurements for the quick, nondestructive, and quantitative measurement of the feature shape and size and line-edge roughness of lithographically prepared structures using a model photoresist pattern consisting of a periodic grating of 0.15micrometers lines. The measurements are performed directly on structures as fabricated on a silicon wafer with no other sample preparation. For well-defined patterns placed normal to the neutron beam, we easily observe up to six orders of diffraction peaks. Analytic expressions from standard small angle scattering formalism are sued to extract the average line structure, spacing, and line-edge roughness from the peak positions and intensities. Additional structural information is obtained by tilting the pattern relative to the incident beam. Changes in the observed scattering data as a function of the tilting angle are related to characteristics such as the height of the structures and the symmetry of the line shape.