Facet type determination based on combined atomic force microscopy and electron backscatter diffraction

The distribution of facet types affects the functionality of the surfaces of polycrystalline films. However, we are not aware of a previously published convenient method to determine their distribution. This work describes and demonstrates a process to determine and map the Miller indexes (hkl) of crystal facets exposed at the surfaces of polycrystalline films. To find facet types in non‐trivial cases, one must know the orientation of the crystal and the direction in which the facet is facing. The method presented here combines the crystal orientations obtained with electron backscatter diffraction with the topography of the same sample area measured with atomic force microscopy. A challenging step is to transfer the data from the two instruments into a common coordinate system. The sequence of steps in the data processing is presented, with methods to verify the results. The process is illustrated with the analysis of an etched copper clad laminate (CCL) and an electroless Cu film deposited on the CCL. This example relates to facet selection in electroless and galvanic plating processes in printed circuit board production, where an uncontrolled transition from epitaxial to non‐epitaxial growth can lead to surfaces with unacceptable roughness. Lay Description Crystals are usually recognized by having distinct facets at their surface. The study of crystals and facets has a long tradition. To identify a crystal facet, one must know the orientation of the surface relative to stacking pattern of the atoms within the crystal. Both these tasks can be accomplished separately, but it is difficult to put the two pieces of information together for hundreds or thousands of crystals at a time. As the dimensions of the electronic circuits become smaller, for example in mobile phones, it is becoming increasingly important to know and control the facets present at the surface of the electrical connections. We measure the topography of the sample surface with Atomic Force Microscopy (AFM) and identify flat parts of the surface as facets. On the same sample, we use a scanning electron microscope with a specialized module (Electron backscatter diffraction, EBSD) to find the directions in which the atoms are stacked below these facets. Combining the data from these two instruments allows us to find the facet types. The mathematical steps needed to do this are described and illustrated. This new technique will allow improved process design and process control in electronics m