シリコンウエハ表面上の微粒子・微小欠陥による光散乱 : 散乱光強度およびレンズによる像形成の計算

概要

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A theory of light scattering is described for particles and geometric defects on a flat suface which are very small compared with the wavelength. The differential scattering cross section for small objects with an arbitrary shape is calculated to the electric-dipole approximation. The image of scatterer through a magnifying lens is also obtained by combining a conventional optical theory. This calculation method is applied to particle, projection, pit and scratch on the silicon wafer, the shape of which is assumed to be rectangular in order to simplify an algebraic expression. The charaoteristics of light scattering are the followings : (1) The intensity of light scattered by particle is proportional to the 6th power of scatterer size and the scattering of p-polarized light is larger than s-polarized one. (2) The orientation : dependence of light intensity scattered by particle, projection and pit takes a shape of doughnut, like a Rayleigh scattering, but the light scattering due to scratch is strong only in the direction perpendicular to the scratch line. (3) The image of scatterers shows a diffraction pattern caused by the aperture of lens.
公益社団法人精密工学会の論文
2000-11-05