A study of lateral roughness evaluation through critical-dimension small angle x-ray scattering (CD-SAXS)

CD-SAXS capabilities are evaluated using a Ultra-SAXS setup allowing measurement of large reciprocal space maps with a high resolution configuration. The measured structures are: i) Tungsten lines gratings and ii) Si-ARC (Silicon Antireflective Coating) lines gratings both deposited onto a thin silicon membrane (100 nm thick). Advanced data reduction is performed thanks to reverse Monte Carlo simulations. Line period, line width, sidewall angle are extracted. Stitching effect was also detected and its period was determined. Peak broadening with peak order is discussed in terms of period dispersion and cumulative roughness. Amplitude and period of lateral roughness is also determined through complementary measurements performed at ESRF.