Round robin determination of power spectral densities of different Si wafer surfaces

摘要

Abstract: Power spectral densities (PSDs) were used to characterize a set of surfaces over a wide range of lateral as well as perpendicular dimensions. Twelve 200-mm-diameter Si wafers were prepared and the surface finished ranged from as-ground wafers to epitaxial wafers. The wafer surfaces were then measured with different methods: atomic force microscopy, angle-resolved light scatter, interferometric and stylus profilometries, and capacitance-based wafer thickness gages. The data were converted into 1D PSDs and the curves were plotted as functions of spatial frequencies. The useful frequency range for each method is indicated and the differences in the calculated PSD values in the overlapping region of two or more methods are discussed. The method used to convert 2D PSDs to 1D ones is presented.!39