Ml. Liswith et al., MODELING OF LIGHT-SCATTERING BY SUBMICROMETER SPHERICAL-PARTICLES ON SILICON AND OXIDIZED SILICON SURFACES, Optical engineering, 35(3), 1996, pp. 858-869
We report angle resolved scattering characteristics of individual subm
icrometer polystyrene spheres on silicon and on a 91.5 nm thick film o
f oxide on silicon. Both these surfaces are considered optically smoot
h because the root mean square (rms) vertical roughness sigma is much
less than the wavelength lambda (sigma much less than lambda). Scatter
ing was measured as a function of polarization using a He-Ne and argon
laser at varying degrees of incident angle. The experimental results
are compared with a semi-analytical model of sphere/surface light scat
tering and a finite-element time-domain electromagnetics code used in
conjunction with a far-field extrapolator called EXTRMAP. The scatteri
ng measurements showed good to excellent agreement with both models. T
he semianalytical model could be improved by fully accounting for stan
ding wave effects, a phenomenon the finite-element time-domain model i
nherently includes. The results are qualitatively explained with refer
ence to both standing wave phenomena and the silicon surface reflectan
ce, which varies significantly as the beam incident angle and polariza
tion are changed. (C) 1996 Society of Photo-Optical Instrumentation En
gineers.