Techniques for analyzing digital elevation models of surface topography of microelectronics objects

Abstract

We discuss techniques for analyzing digital elevation models (DEMs) of surface topography of microelectronics objects exemplified by silicon wafers and wafer-based structures, such as SiO₂/Si wafers, silicon–glass assemblies, thin film membranes formed by the Bosch process, and Ni–W films on Bi₂Te₃ substrate. We describe approaches to calculate and analyze wafer curvature using (1) data of curvature of DEM profiles, (2) second partial derivatives computed from DEMs, as well as (3) geomorphometric methods (e.g., analysis of digital models and maps of Gaussian, mean, and principal curvatures as well as other morphometric variables derived from DEMs). We show possibilities of using digital models and maps of catchment area derived from DEMs to analyze location of microcrests of wafer surface. We demonstrate capabilities of these techniques for analyzing volumetric defects. We also present specific recommendations for handling experimental data, such as DEM smoothing by approximation and processing DEMs with voids.