Large-angle in-plane light scattering from rough surfaces

An in-plane light scattering setup that is capable of measuring large azimu thal scattering angles is presented. This type of measurement makes it easi er to probe large k(\\) at a fixed k(perpendicular to) value (k(\\) and k(p erpendicular to) are momentum transfer vectors parallel and perpendicular t o the surface, respectively). Therefore the system allows us to explore sma ll lateral scale and large vertical roughness (similar to lambda, the wavel ength of the probe beam) of a rough surface. In-plane intensity measurement s from a rough backside Si wafer and a Cu thin-film surface are reported. T he structure factor that is related to surface roughness parameters is obta ined from the measured in-plane intensity profiles. Both scalar (Beckmann-K irchhoff) and vector (Rayleigh-Rice) theories have been applied to interpre t the experimental data. The roughness parameters obtained from the scatter ing measurements are compared with those measured by atomic-force microscop y. (C) 2000 Optical Society of America OCIS codes: 290.5880, 290.5820, 240. 5770, 050.1960.