The University of British Columbia

We report the use of coherent soft X-ray scattering, or speckle, to study the morphology of random surfaces on single crystal semiconductor substrates. The experiments were carried out with photon energies in the 266-290 eV range. The effect of the magnitude of the roughness on the scattering was observed by measuring speckle patterns at various angles of incidence from two different surfaces with InP islands in the nanometer size range and in the micron range. The effect of element-specific resonant scattering was explored with a PMMA-coated textured silicon sample by tuning the wavelength to the carbon K-edge. Two dimensional numerical simulations of the coherent scattering have been carried out in the Fraunhofer approximation, using AFM data for the sample surface morphology. Good agreement with the observed speckle patterns was obtained, taking into account the 20 mu m lateral coherence length of the source.