Radiative Properties of Anisotropic Microrough Silicon Surfaces

Abstract

** † Recent studies have shown that the topography of some chemically etched microrough silicon surfaces is non-Gaussian and may be strongly anisotropic. However, the effect of anisotropy on the out-of-plane bidirectional reflectance distribution function (BRDF) and the surface emittance has not been fully understood. The present work employs the Monte Carlo ray-tracing method to predict the radiative properties by using the topographic data measured from an atomic force microscope. The predicted in-plane BRDFs agree well with experiments using a three-axis automatic scatterometer. The calculated results demonstrate that dramatic differences exist in the two-dimensional BRDFs for surfaces with different microfacet slope distributions and a relative error of as large as 3% exists in the predicted emittance of the anisotropic surface if a Gaussian distribution is assumed. This research will not only facilitate the fundamental understanding of the radiative properties of rough surfaces, but also benefit the semiconductor manufacturing industry in terms of accurate radiometric temperature measurements during the rapid thermal processing.