Near-field Soft X-ray Diffraction Modelled by the Multislice Method

Diffraction effects may limit the spatial resolution and fidelity of soft X-ray lithography and contact microradiography, by scattering during transmission of X rays through a finite-thickness object, and in subsequent propagation to the image-recording plane. A numerical method is described to model such soft X-ray scattering effects, developed from the multislice method for electron diffraction calculations. Computer simulations are presented of scattering by sub-micron latex spheres used as test objects in contact microradiography, and carbon-like gratings used as lithographic masks. The calculated diffraction by spheres is shown to be consistent with experimental results and a rigorous Mie scattering calculation, and the calculations for gratings suggest the possibility of frequency-doubling lithography under carefully controlled conditions.