Crystal facets and surface morphology as a function of crystal orientation by automatic alignment of AFM and EBSD data: application to etched copper polycrystals

Abstract

Electron backscatter diffraction (EBSD) is used to determine the orientations of crystals on sample surfaces. In conjunction with the surface topography from atomic force microscopy (AFM), the facets of the crystals can be computed. Reconciling the coordinate systems of the EBSD and AFM measurements is a challenging and time-consuming process for rough polycrystal surfaces. This paper presents a novel method for importing EBSD data into the AFM coordinate system with minimal user input. This method proceeds by simulating EBSD band contrast images from the AFM topography. Then, a mapping between this simulated and the measured EBSD band contrast image is established by least-squares fitting. With this mapping, the EBSD data are projected onto the AFM coordinate system. In addition to automatic facet type determination, this enables a statistical analysis of the relation between the orientation and surface morphology of individual crystals on polycrystal surfaces. As an application example we analyze etched copper surfaces that are obtained in intermediate steps of the production of printed circuit boards (PCBs). Based on about 150 crystals, the analysis reveals a characteristic dependence of roughness and surface features such as ridges and etch hillocks on the crystal orientation.